CN112443331B - Disturbance sensitive stratum ultra-small clear distance large section group-hole parallel subway tunnel construction method - Google Patents
Disturbance sensitive stratum ultra-small clear distance large section group-hole parallel subway tunnel construction method Download PDFInfo
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- 238000010276 construction Methods 0.000 title claims abstract description 147
- 238000000034 method Methods 0.000 claims abstract description 108
- 238000009412 basement excavation Methods 0.000 claims abstract description 83
- 230000002787 reinforcement Effects 0.000 claims abstract description 57
- 229910000831 Steel Inorganic materials 0.000 claims description 128
- 239000010959 steel Substances 0.000 claims description 128
- 239000011440 grout Substances 0.000 claims description 42
- 239000002689 soil Substances 0.000 claims description 35
- 239000002002 slurry Substances 0.000 claims description 28
- 239000007788 liquid Substances 0.000 claims description 24
- 239000004568 cement Substances 0.000 claims description 19
- 235000019353 potassium silicate Nutrition 0.000 claims description 13
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims description 13
- 238000003466 welding Methods 0.000 claims description 12
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- 238000005553 drilling Methods 0.000 claims description 10
- 230000003014 reinforcing effect Effects 0.000 claims description 9
- 230000005641 tunneling Effects 0.000 claims description 9
- 238000005192 partition Methods 0.000 claims description 8
- 238000005728 strengthening Methods 0.000 claims description 7
- 238000009792 diffusion process Methods 0.000 claims description 6
- 238000004519 manufacturing process Methods 0.000 claims description 6
- 238000005086 pumping Methods 0.000 claims description 6
- 238000007789 sealing Methods 0.000 claims description 6
- 238000005336 cracking Methods 0.000 abstract description 3
- 239000011435 rock Substances 0.000 description 4
- 230000002093 peripheral effect Effects 0.000 description 3
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- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D9/00—Tunnels or galleries, with or without linings; Methods or apparatus for making thereof; Layout of tunnels or galleries
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
- E21D11/04—Lining with building materials
- E21D11/10—Lining with building materials with concrete cast in situ; Shuttering also lost shutterings, e.g. made of blocks, of metal plates or other equipment adapted therefor
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
- E21D11/14—Lining predominantly with metal
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D21/00—Anchoring-bolts for roof, floor in galleries or longwall working, or shaft-lining protection
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D9/00—Tunnels or galleries, with or without linings; Methods or apparatus for making thereof; Layout of tunnels or galleries
- E21D9/14—Layout of tunnels or galleries; Constructional features of tunnels or galleries, not otherwise provided for, e.g. portals, day-light attenuation at tunnel openings
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Abstract
The invention discloses a disturbance sensitive stratum ultra-small clear distance large section group hole parallel subway tunnel construction method which comprises five steps of middle large end face tunnel construction, small clear distance tunnel construction, standard section tunnel construction, outer large end face tunnel construction, tunnel group secondary reinforcement and the like. The method effectively solves the problems that in a disturbance sensitive stratum excavated in a city, underground excavation construction is carried out on a group of ultra-small clear distance large section holes parallel to a subway tunnel, and the excavation construction of a rear hole easily causes overlarge deformation of a primary support of a front hole and cracking of a secondary lining, and the like.
Description
Technical Field
The invention relates to the field of underground engineering, in particular to a construction method of a disturbance sensitive stratum ultra-small clear distance large section group-hole parallel subway tunnel.
Background
Subway engineering is generally located the urban area, and the construction site is narrow and small, peripheral pipeline is intensive, road traffic load is big, peripheral building is intensive etc. complex environment, and is strict to the stable and deformation control in stratum, once unstability can cause the heavy loss of life and property. With the rapid development of urban rail transit construction in China, the number of subway stations which are transferred from one station to another station is gradually increased, the construction of tunnels with multiple caverns and large sections becomes a trend, and a plurality of challenges are brought to the construction of group-tunnel parallel tunnels with ultra-small clear distance and large sections in urban sensitive environments.
In the group tunnel construction, the excavation of each pilot tunnel can generate mutual influence, and peripheral surrounding rocks of a preceding cavern are loosened in the construction to generate stress redistribution, so that the construction of the cavern which is next to the preceding cavern generates larger settlement deformation; meanwhile, surrounding rock stress is released in the backward grotto construction, secondary loosening deformation of the surrounding rock close to the forward grotto is caused, the primary support structure bears larger surrounding rock pressure, and if the support structure deforms too much to crack, great influence is caused on the tunnel structure and safety. For the condition of ultra-small clear distance large section group tunnel construction, the large section tunnel construction mostly adopts the methods of CD, CRD, double side wall pilot tunnel and the like, the working procedures are more, temporary supports need to be removed before secondary lining construction, the large section tunnel construction has greater risks, and the mutual influence control in the tunnel construction is particularly important when the ultra-small clear distance is superposed to close to the tunnel construction working condition.
In the current stage, a method for grouting and reinforcing soil bodies among tunnels is mostly adopted for controlling the mutual influence of the small clear distance tunnel construction, and a method for optimizing the excavation mode of the large-section tunnel and the group tunnel excavation process is generally adopted for controlling the mutual influence of the large-section group tunnel construction. However, in a disturbance sensitive stratum of urban subway excavation, construction of a group tunnel with ultra-small clear distance and large section is carried out, because the excavation stratum is more sensitive, the tunnel span is larger, the distance between chambers is closer, the control effect is difficult to achieve by adopting a single control measure, meanwhile, the working time of the two liners is also extremely important, and if the traditional scheme that the two liners are close to the primary support construction is adopted, the deformation of the chambers in the first row is too large in the excavation construction of the chambers in the later row, and the phenomenon that the two liners are broken can be generated. Therefore, in order to meet the requirements of safe and reliable actual construction, a method for controlling construction aiming at mutual influence of ultra-small clear distance and large section group-tunnel parallel tunnels in urban subway construction needs to be developed urgently.
Disclosure of Invention
The invention discloses a method for constructing a disturbance sensitive stratum ultra-small clear distance large section group tunnel parallel subway tunnel, which aims to solve the problems in the prior art.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows:
the method for constructing the disturbance sensitive stratum ultra-small clear distance large section group-hole parallel subway tunnel comprises the following steps:
s1, constructing a middle large-end-face tunnel, excavating and constructing the middle large-section tunnel by adopting a double-side-wall pit guiding method, constructing pilot holes in a construction working face of the middle large-end-face tunnel in sequence, performing full-section deep-hole grouting on a deep-hole grouting reinforcement area before pilot hole excavation, supporting the construction working face through a grid steel frame, constructing each pilot hole by adopting an upper-lower step method, staggering the upper step and the lower step by 3-5 m, reserving core soil on the upper step, drilling two locking anchor pipes at each step arch foot, reliably welding locking anchor rods with the grid steel frame, and staggering the front and back of each pilot hole by not less than 8 m;
s2, constructing a small clear distance tunnel, after completing S1 construction, symmetrically constructing the small clear distance tunnel on two sides of the tunnel constructed in the S1 step by adopting a step method, performing full-section deep hole grouting on a deep hole grouting reinforcement area before pilot tunnel excavation, supporting a construction working face through a grid steel frame, sealing a primary support to form a ring in time, enabling the primary support to be spaced from a large-section tunnel pilot tunnel by not less than 8m, constructing by adopting an upper step method and a lower step method, staggering the upper step and the lower step by 3-5 m, reserving core soil on the upper step, erecting the grid steel frame for supporting after pilot tunnel excavation, and simultaneously arranging a foot locking anchor rod and spraying concrete for supporting and strengthening, wherein the foot locking anchor rod is reliably welded with the grid, and each pilot tunnel is staggered from front to back by not less than 8 m;
s3, standard section tunnel construction, after S2 construction is completed, an outermost standard section tunnel is symmetrically constructed and constructed outside the tunnel constructed and constructed in S2 by adopting a step method, full-section deep hole grouting is firstly carried out on a deep hole grouting reinforcement area before pilot tunnel excavation, a construction working face is supported by a grid steel frame, a primary support is sealed into a ring in time and is spaced by 8m from an adjacent tunnel pilot tunnel, then construction is carried out by adopting an upper step method and a lower step method, the upper step and the lower step are staggered by 3-5 m, core soil is reserved at the upper step, the grid steel frame is erected after pilot tunnel excavation, a foot locking anchor rod is arranged, and concrete spraying support reinforcement is carried out, wherein the foot locking anchor rod is reliably welded with the grid, and each pilot tunnel is staggered by not less than 8m from front to back;
s4, constructing an outer side large-end-face tunnel, and after the construction of the S3 step is completed, constructing an outermost side large-section tunnel by a CRD method, wherein full-section deep hole grouting is firstly carried out on a deep hole grouting reinforcement area before pilot tunnel excavation, a construction working face is supported by a grid steel frame, a primary support is timely sealed to form a ring and is spaced by 8m from an adjacent tunnel pilot tunnel, then construction is carried out by an upper step and a lower step, the upper step and the lower step are staggered by 3-5 m, core soil is reserved on the upper step, two foot-locking anchor pipes are arranged at each step arch foot, foot-locking anchor rods are reliably welded with grids, and the front and back staggering of each pilot tunnel is not less than 8 m;
and S5, secondarily reinforcing the tunnel group, performing secondary lining construction after the construction of the step S4 is completed, completing the construction in all the steps S1 to S4, and performing secondary lining construction after the stratum deformation tends to be stable, in the large-section secondary lining construction of the double-side-wall pit guiding method, only chiseling the surface concrete of the primary support during the primary support dismantling operation, performing waterproof treatment on the grid steel frame, and completing the integral construction of the tunnel after the secondary reinforcement is completed, wherein the dismantling length is not more than 6m each time during the primary support dismantling.
Further, in the steps S1-S4, when full-section deep hole grouting is performed on the deep hole grouting reinforcement area before pilot tunnel excavation, the grouting range is 2-5 m outside the primary support profile, grout is cement-water-glass double-liquid grout, the grouting footage is 10m, the tunneling is 8m, and the tail end 2m is a grout stop wall for next grouting; hole sites need to be marked at grouting positions in deep hole grouting, hole site deviation of drilling is not more than 200mm, hole forming deflection rate is not more than 1%, according to grouting ranges and tunnel excavation forms, transverse channels and interval underground tunnel full-section grouting holes are arranged in the deep hole grouting holes, after deep hole grouting reinforcement of each pilot tunnel, a small advanced guide pipe needs to be arranged in a 120-degree range of a vault before pilot tunnel excavation, the size of the small guide pipe is DN32 multiplied by 2.75 steel welded pipes, the length of the small guide pipe is 2-3 m, the circumferential spacing is 0.1-0.5 m, the longitudinal spacing is 0.5-1.5 m, the small guide pipe is only used for filling grouting, and grout is selected from cement paste; in the process of manufacturing the small guide pipe, the steel pipe is cut into required length, one end of the steel pipe is made into a cone shape with the length of 200-400 mm, no hole is formed in the range of 1000mm at the tail end, and slurry overflow holes with the diameter of 6-8 mm are distributed in a quincunx shape at intervals of 150-200 mm in the rest part.
Further, when the grouting operation is performed on the grouting holes, the method comprises the following steps:
firstly, excavating a pilot tunnel close to a soil-facing side, arranging double rows of grouting holes in a quincunx shape at a position 400-600 mm away from the soil-facing side, and arranging the grouting holes in the quincunx shape at a distance of @800mm multiplied by 800mm in the middle of the pilot tunnel; in the soil-filled and sandy gravel stratum, the grouting pressure is preferably controlled to be 0.5-1.0 MPa, the rest of the stratum is preferably controlled to be 1-2 MPa, the diffusion radius is 0.4-0.6 m, and the distance between the end parts of grouting holes is 0.7-0.9 m.
And secondly, preparing cement paste and water glass paste by using the cement-water glass double-liquid slurry respectively, pumping by using a double-liquid grouting pump, mixing in a mixer, and injecting into an engineering object after mixing.
Further, the cement-water glass double-liquid slurry is mixed according to the proportion of 1: 1-1: 0.6 of cement slurry and water glass slurry.
Further, in the steps S1 to S4, the thickness of the primary support is 0.35m, the thickness of the temporary support is 0.3m, the longitudinal distance between the grid steel frames is 0.3 to 0.8m, the main grid ribs, the truss ribs and the longitudinal connecting ribs are HRB400 steel bars, the rest are HPB300 steel bars, and the temporary middle partition wall is made of Q235b steel; the foot-locking anchor rod adopts DN32 multiplied by 2.75 steel welded pipe, the length is 2.5m, and the incident angle is 45 degrees.
Further, in the step S2, during tunnel excavation supporting, when the clear distance between the primary supports is less than or equal to 1.8m, a 2m long DN32 small conduit needs to be drilled at one side of the backward excavated tunnel in the tunnel excavated in the previous period, and filling and grouting are performed, and in the process of excavating the backward tunnel, the redundant small conduit is cut off and welded and fixed with the grid steel frame, and is also used as a lock pin anchor pipe of the backward excavated tunnel.
The method effectively solves the problems that in a disturbance sensitive stratum excavated in a city, underground excavation construction is carried out on a group of ultra-small clear distance large section holes parallel to a subway tunnel, and the excavation construction of a rear hole easily causes overlarge deformation of a primary support of a front hole and cracking of a secondary lining, and the like.
Drawings
FIG. 1 is a schematic view of the construction process of the present invention;
FIG. 2 is a cross-sectional view of the excavation of the present invention;
FIG. 3 is a view of the construction of the support of the present invention;
FIG. 4 is a sequence diagram of longitudinal construction of double-side wall pit guiding method excavation;
in the figure 1-pilot hole 1; 2-guiding the hole 2; 3-guiding a hole 3; 4-pilot hole 4; 5-guiding a hole 5; 6-pilot tunnel 6; 7-a tunnel 7; 8-tunnel 8; 9-tunnel 9; 10-pilot hole 10; 11-pilot hole 11; 12-pilot hole 12; 13-pilot hole 13; 14-advanced small catheter; 15-deep hole grouting reinforcement area; 16-a small duct 16; 17-locking anchor pipe; 18-temporary support 18; 19-primary support 19; 20-primary support 20; 21-temporary support 21; 22-primary support 22; 23-primary support 23; 24-secondary lining 24; 25-secondary lining 25; 26-secondary lining 26; 27-secondary lining 27; 28-Secondary Lining 28.
Detailed Description
The invention will be better understood from the following examples. However, those skilled in the art will readily appreciate that the description of the embodiments is only for illustrating the present invention and should not be taken as limiting the invention as detailed in the claims.
As shown in fig. 1-4, the method for constructing the disturbance sensitive stratum ultra-small clear distance large section group-hole parallel subway tunnel comprises the following steps:
s1, constructing a middle large-end-face tunnel, excavating and constructing the middle large-section tunnel by adopting a double-side-wall pilot tunnel method, constructing pilot holes in a construction working face of the middle large-end-face tunnel in sequence, performing full-section deep-hole grouting on a deep-hole grouting reinforcement area before pilot hole excavation, supporting the construction working face through a grid steel frame, constructing each pilot hole by adopting an upper and lower step method, staggering the upper and lower steps for 3-5 m, reserving core soil on the upper step, drilling two locking anchor pipes at each step arch foot, and reliably welding the locking anchor rods with the grid steel frame, wherein the front and back staggering of each pilot hole is not less than 8 m;
s2, constructing a small clear distance tunnel, after completing S1 construction, symmetrically constructing the small clear distance tunnel on two sides of the tunnel constructed in the S1 step by adopting a step method, performing full-section deep hole grouting on a deep hole grouting reinforcement area before pilot tunnel excavation, supporting a construction working face through a grid steel frame, sealing a primary support to form a ring in time, enabling the primary support to be spaced from a large-section tunnel pilot tunnel by not less than 8m, constructing by adopting an upper step method and a lower step method, staggering the upper step and the lower step by 3-5 m, reserving core soil on the upper step, erecting the grid steel frame for supporting after pilot tunnel excavation, and simultaneously arranging a foot locking anchor rod and spraying concrete for supporting and strengthening, wherein the foot locking anchor rod is reliably welded with the grid, and each pilot tunnel is staggered from front to back by not less than 8 m;
s3, standard section tunnel construction, after S2 construction is completed, an outermost standard section tunnel is symmetrically constructed and constructed outside the tunnel constructed and constructed in S2 by adopting a step method, full-section deep hole grouting is firstly carried out on a deep hole grouting reinforcement area before pilot tunnel excavation, a construction working face is supported by a grid steel frame, a primary support is sealed into a ring in time and is spaced by 8m from an adjacent tunnel pilot tunnel, then construction is carried out by adopting an upper step method and a lower step method, the upper step and the lower step are staggered by 3-5 m, core soil is reserved at the upper step, the grid steel frame is erected after pilot tunnel excavation, a foot locking anchor rod is arranged, and concrete spraying support reinforcement is carried out, wherein the foot locking anchor rod is reliably welded with the grid, and each pilot tunnel is staggered by not less than 8m from front to back;
s4, constructing an outer side large-end-face tunnel, and after the construction of the S3 step is completed, constructing an outermost side large-section tunnel by a CRD method, wherein full-section deep hole grouting is firstly carried out on a deep hole grouting reinforcement area before pilot tunnel excavation, a construction working face is supported by a grid steel frame, a primary support is timely sealed to form a ring and is spaced by 8m from an adjacent tunnel pilot tunnel, then construction is carried out by an upper step and a lower step, the upper step and the lower step are staggered by 3-5 m, core soil is reserved on the upper step, two foot-locking anchor pipes are arranged at each step arch foot, foot-locking anchor rods are reliably welded with grids, and the front and back staggering of each pilot tunnel is not less than 8 m;
and S5, secondarily reinforcing the tunnel group, performing secondary lining construction after the construction of the step S4 is completed, completing the construction in all the steps S1 to S4, and performing secondary lining construction after the stratum deformation tends to be stable, in the large-section secondary lining construction of the double-side-wall pit guiding method, only chiseling the surface concrete of the primary support during the primary support dismantling operation, performing waterproof treatment on the grid steel frame, and completing the integral construction of the tunnel after the secondary reinforcement is completed, wherein the dismantling length is not more than 6m each time during the primary support dismantling.
It is important to explain that in the steps S1-S4, when full-face deep hole grouting is performed on a deep hole grouting reinforcement area before pilot tunnel excavation, the grouting range is 2-5 m outside the primary support profile, grout is cement-water-glass double-fluid grout, the grouting footage is 10m, the tunneling is 8m, and the tail end 2m is a grout stop wall for next grouting; hole sites need to be marked at grouting positions in deep hole grouting, hole site deviation of drilling is not more than 200mm, hole forming deflection rate is not more than 1%, according to grouting ranges and tunnel excavation forms, transverse channels and interval underground tunnel full-section grouting holes are arranged in the deep hole grouting holes, after deep hole grouting reinforcement of each pilot tunnel, a small advanced guide pipe needs to be arranged in a 120-degree range of a vault before pilot tunnel excavation, the size of the small guide pipe is DN32 multiplied by 2.75 steel welded pipes, the length of the small guide pipe is 2-3 m, the circumferential spacing is 0.1-0.5 m, the longitudinal spacing is 0.5-1.5 m, the small guide pipe is only used for filling grouting, and grout is selected from cement paste; during the manufacture of the small conduit, a steel pipe is cut into a required length, one end of the steel pipe is made into a cone shape with the length of 200-400 mm, no hole is formed in the range of 1000mm at the tail end, and slurry overflow holes with the diameter of 6-8 mm are distributed in a quincunx shape at intervals of 150-200 mm in the rest part.
It should be particularly noted that, during the grouting operation of the grouting holes, the following steps are performed:
firstly, excavating a pilot tunnel close to the position of the soil-facing side, arranging two rows of grouting holes in a quincunx manner at a position 400-600 mm away from the soil-facing side, and arranging the grouting holes in a quincunx manner at a distance of @800mm multiplied by 800mm in the middle of the pilot tunnel; in the soil-filled and sandy gravel stratum, the grouting pressure is preferably controlled to be 0.5-1.0 MPa, the rest of the stratum is preferably controlled to be 1-2 MPa, the diffusion radius is 0.4-0.6 m, and the distance between the end parts of grouting holes is 0.7-0.9 m.
And secondly, preparing cement paste and water glass paste by using the cement-water glass double-liquid slurry respectively, pumping by using a double-liquid grouting pump, mixing in a mixer, and injecting into an engineering object after mixing.
Preferably, the cement-water glass double-liquid slurry is mixed with the water glass slurry in a ratio of 1: 1-1: 0.6.
In addition, in the steps S1-S4, the thickness of a primary support is 0.35m, the thickness of a temporary support is 0.3m, the longitudinal distance between grid steel frames is 0.3-0.8 m, main grid ribs, truss ribs and longitudinal connecting ribs are HRB400 steel bars, the balance of HPB300 steel bars, and a temporary middle partition wall is made of Q235b steel bars; the foot-locking anchor rod adopts DN32 multiplied by 2.75 steel welded pipe, the length is 2.5m, and the incident angle is 45 degrees.
In this embodiment, in the step S2, during the tunnel excavation supporting, when the clear distance between the primary supports is less than or equal to 1.8m, a 2m long DN32 small conduit needs to be drilled at one side of the backward excavated tunnel in the tunnel to be excavated in the previous stage, and filling and grouting are performed, and in the process of excavating the backward tunnel, the redundant small conduits are cut off and welded and fixed with the grid steel frame, and are also used as the pin-locking anchor pipes of the backward excavated tunnel.
The invention is described below with reference to specific engineering examples. The engineering example is implemented under the technical scheme of the invention, specific embodiments and operation procedures are given, but the protection scope of the invention is not limited to the following examples.
EXAMPLE 1
As shown in fig. 1-4, the method for constructing the disturbance sensitive stratum ultra-small clear distance large section group-hole parallel subway tunnel comprises the following steps:
s1, constructing a middle large-end-face tunnel, excavating and constructing the middle large-section tunnel by adopting a double-side-wall pilot tunnel method, constructing pilot holes 1 to 6 in a construction working face of the middle large-end-face tunnel in sequence, performing full-section deep-hole grouting on a deep-hole grouting reinforcement area before pilot hole excavation, supporting the construction working face through a grid steel frame, constructing each pilot hole by adopting an upper and lower step method, staggering 3m from the upper and lower steps, reserving core soil on the upper step, drilling two locking anchor pipes at each step arch foot, reliably welding locking anchor rods with the grid steel frame, and staggering 8m from the front and back of each pilot hole;
s2, constructing a small clear distance tunnel, after completing S1 construction, symmetrically constructing the small clear distance tunnel at two sides of the tunnel constructed in the step S1 by adopting a step method, carrying out full-section deep hole grouting on a deep hole grouting reinforcement area before pilot tunnel excavation, supporting a construction working face through a grid steel frame, sealing a primary support into a ring in time, spacing 8m from a large-section tunnel pilot tunnel, constructing by adopting an upper step method and a lower step method, staggering 3m from the upper step and the lower step, reserving core soil on the upper step, erecting the grid steel frame for supporting after the pilot tunnel excavation, simultaneously arranging a foot locking anchor rod and spraying concrete for supporting and reinforcing, wherein the foot locking anchor rod is reliably welded with the grid, and staggering 8m from front to back of each pilot tunnel;
s3, standard section tunnel construction, after S2 construction is completed, the outermost standard section tunnel is symmetrically constructed and constructed outside the tunnel constructed and constructed in S2 by adopting a step method, full-section deep hole grouting is firstly carried out on a deep hole grouting reinforcement area before pilot tunnel excavation, a construction working face is supported by a grid steel frame, a primary support is sealed into a ring in time and is spaced by 8m from an adjacent tunnel pilot tunnel, then construction is carried out by adopting an upper step method and a lower step method, the upper step and the lower step are staggered by 3m, core soil is reserved on the upper step, the grid steel frame is erected after pilot tunnel excavation, a foot locking anchor rod is arranged and sprayed with concrete for supporting and strengthening, wherein the foot locking anchor rod is reliably welded with the grid, and each pilot tunnel is staggered by 8m from front to back;
s4, constructing an outer side large-end-face tunnel, and after the construction of the S3 step is completed, constructing an outermost side large-section tunnel by a CRD method, wherein full-section deep hole grouting is firstly carried out on a deep hole grouting reinforcement area before pilot tunnel excavation, a construction working face is supported by a grid steel frame, a primary support is timely sealed to form a ring and is spaced by 8m from an adjacent tunnel pilot tunnel, then construction is carried out by an upper step and a lower step, the upper step and the lower step are staggered by 3m, core soil is reserved on the upper step, two locking anchor pipes are arranged at arch feet of each step, locking anchor rods are reliably welded with grids, and each pilot tunnel is staggered by 8m from front to back;
and S5, secondarily reinforcing the tunnel group, after the construction of the S4 step is completed, performing secondary lining construction after the construction is completely completed in the steps from S1 to S4 and the stratum deformation tends to be stable, in the construction of the secondary lining with the large section by the double-side-wall pit guide method, only chiseling the surface concrete of the primary support during the primary support dismantling operation, performing waterproof treatment on the grid steel frame, and completing the integral construction of the tunnel after the secondary reinforcement is completed, wherein the dismantling length is 6m each time during the primary support dismantling.
In this embodiment, in the steps S1-S4, when full-face deep hole grouting is performed on a deep hole grouting reinforcement area before pilot tunnel excavation, the grouting range is 2m outside the primary support profile, grout is cement-water-glass double-liquid grout, the grouting footage is 10m, the excavation is 8m, and the end 2m is a grout stop wall for the next grouting; hole sites need to be marked at grouting positions in deep hole grouting, hole site deviation of drilling is not more than 200mm, hole forming deflection rate is not more than 1%, according to grouting ranges and tunnel excavation forms, transverse channels and interval underground tunnel full-section grouting holes are arranged in the deep hole grouting holes, after deep hole grouting reinforcement of each pilot tunnel, a small advanced guide pipe needs to be arranged in a 120-degree range of a vault before pilot tunnel excavation, the size of the small guide pipe is DN32 multiplied by 2.75 steel welded pipes, the length of the small guide pipe is 2m, the circumferential spacing is 0.1m, the longitudinal spacing is 0.5m, the small guide pipe is only used for filling grouting, and grout is selected; in the process of manufacturing the small guide pipe, the steel pipe is cut into the required length, one end of the steel pipe is made into a 200mm long cone shape, a hole is not formed in the range of 1000mm at the tail end, and slurry overflow holes with the diameter of 6mm are distributed in the rest part at intervals of 150mm quincunx.
Wherein, during grouting operation of the grouting holes, the method comprises the following steps:
firstly, excavating a pilot tunnel close to a soil-facing side, arranging double rows of grouting holes in a quincunx manner at a position 400mm away from the soil-facing side, and arranging the grouting holes in the quincunx manner at a distance of @800mm multiplied by 800mm in the middle of the pilot tunnel; in the stratum filled with soil and sand pebbles, the grouting pressure is preferably controlled to be 0.5MPa, the rest of the stratum is preferably controlled to be 1MPa, the diffusion radius is 0.4m, and the distance between the end parts of grouting holes is 0.7 m.
And secondly, preparing cement paste and water glass paste by using the cement-water glass double-liquid slurry respectively, pumping by using a double-liquid grouting pump, mixing in a mixer, and injecting into an engineering object after mixing.
In addition, the cement-water glass double-liquid slurry is mixed according to the proportion of 1:1 of cement slurry and water glass slurry.
Further, in the steps S1-S4, the thickness of the primary support is 0.35m, the thickness of the temporary support is 0.3m, the longitudinal spacing of the grid steel frames is 0.3m, the main grid ribs, the truss ribs and the longitudinal connecting ribs are HRB400 steel bars, the rest are HPB300 steel bars, and the temporary middle partition wall adopts Q235b steel; the foot-locking anchor rod adopts DN32 multiplied by 2.75 steel welded pipe, the length is 2.5m, and the incident angle is 45 degrees.
It should be noted that, in the step S2, during the tunnel excavation supporting, when the clear distance between the primary supports is less than or equal to 1.8m, a 2m long DN32 small conduit needs to be drilled at one side of the backward excavated tunnel in the tunnel excavated in the previous period, and filling and grouting are performed, and in the process of excavating the backward tunnel, the redundant small conduit is cut off and welded and fixed with the grid steel frame, and is also used as a lock pin anchor pipe of the backward excavated tunnel.
Example 2
As shown in fig. 1-4, the method for constructing the disturbance sensitive stratum ultra-small clear distance large section group-hole parallel subway tunnel comprises the following steps:
s1, constructing a middle large-end-face tunnel, excavating and constructing the middle large-section tunnel by adopting a double-side-wall pilot tunnel method, constructing pilot holes 1 to 6 in a construction working face of the middle large-end-face tunnel in sequence, performing full-section deep-hole grouting on a deep-hole grouting reinforcement area before pilot hole excavation, supporting the construction working face through a grid steel frame, constructing each pilot hole by adopting an upper and lower step method, staggering the upper and lower steps by 5m, reserving core soil on the upper step, arranging two locking anchor pipes at arch feet of each step, reliably welding the locking anchor rods with the grid steel frame, and staggering the front and back of each pilot hole by 10 m;
s2, constructing a small clear distance tunnel, after completing S1 construction, symmetrically constructing the small clear distance tunnel at two sides of the tunnel constructed in the S1 step by adopting a step method, performing full-section deep hole grouting on a deep hole grouting reinforcement area before pilot tunnel excavation, supporting a construction working face through a grid steel frame, sealing a primary support into a ring in time, spacing 9m from a large-section tunnel pilot tunnel, constructing by adopting an upper step method and a lower step method, staggering the upper step and the lower step by 5m, reserving core soil on the upper step, erecting the grid steel frame for supporting after the pilot tunnel excavation, and simultaneously arranging a foot locking anchor rod and spraying concrete for supporting and strengthening, wherein the foot locking anchor rod is reliably welded with the grid, and staggering the front and the back of each pilot tunnel by 10 m;
s3, standard section tunnel construction, after S2 construction is completed, an outermost standard section tunnel is symmetrically constructed and constructed outside the tunnel constructed and constructed in S2 by adopting a step method, full-section deep hole grouting is firstly carried out on a deep hole grouting reinforcement area before pilot tunnel excavation, a construction working face is supported by a grid steel frame, a primary support is sealed into a ring in time and is spaced by 8m from an adjacent tunnel pilot tunnel, then construction is carried out by adopting an upper step method and a lower step method, the upper step and the lower step are staggered by 5m, core soil is reserved on the upper step, the grid steel frame is erected after pilot tunnel excavation, a foot locking anchor rod is arranged and sprayed with concrete for supporting and strengthening, wherein the foot locking anchor rod is reliably welded with the grid, and each pilot tunnel is staggered by 9m from front to back;
s4, constructing an outer side large-end-face tunnel, and after the construction of the S3 step is completed, constructing an outermost side large-section tunnel by a CRD method, wherein full-section deep hole grouting is firstly carried out on a deep hole grouting reinforcement area before pilot tunnel excavation, a construction working face is supported by a grid steel frame, a primary support is timely sealed to form a ring and is spaced by 8m from an adjacent tunnel pilot tunnel, then construction is carried out by an upper step and a lower step, the upper step and the lower step are staggered by 55m, core soil is reserved on the upper step, two foot-locking anchor pipes are arranged at each step arch foot, foot-locking anchor rods are reliably welded with grids, and each pilot tunnel is staggered by not less than 8m from front to back;
and S5, secondarily reinforcing the tunnel group, performing secondary lining construction after the construction of the step S4 is completed, completing the construction in all the steps S1 to S4, and performing secondary lining construction after the stratum deformation tends to be stable, in the large-section secondary lining construction of the double-side-wall pit guiding method, only chiseling the surface concrete of the primary support during the primary support dismantling operation, performing waterproof treatment on the grid steel frame, and completing the integral construction of the tunnel after the secondary reinforcement is completed, wherein the dismantling length is not more than 6m each time during the primary support dismantling.
In the steps S1-S4, when full-face deep-hole grouting is performed on a deep-hole grouting reinforcement area before pilot tunnel excavation, the grouting range is 5m outside the primary support profile, the grout is cement-water-glass double-liquid grout, the grouting footage is 10m, the tunneling is 8m, and the tail end 2m is a grout stop wall for the next grouting; hole sites need to be marked at grouting positions in deep hole grouting, hole site deviation of drilling is not more than 200mm, hole forming deflection rate is not more than 1%, according to grouting ranges and tunnel excavation forms, transverse channels and interval underground tunnel full-section grouting holes are arranged in the deep hole grouting holes, after deep hole grouting reinforcement of each pilot tunnel, a small advanced guide pipe needs to be arranged in a 120-degree range of a vault before pilot tunnel excavation, the size of the small guide pipe is DN32 multiplied by 2.75 steel welded pipes, the length of the small guide pipe is 3m, the circumferential spacing is 0.5m, the longitudinal spacing is 1.5m, the small guide pipe is only used for filling grouting, and grout is selected; in the process of manufacturing the small guide pipe, the steel pipe is cut into the required length, one end of the steel pipe is made into a 400mm long cone shape, a hole is not formed in the range of 1000mm at the tail end, and slurry overflow holes with the diameter of 8mm are distributed in the remaining part at intervals of 200mm quincunx.
In addition, when the grouting operation is carried out through the grouting holes, the following steps are carried out:
firstly, excavating a pilot tunnel close to the position of the soil-facing side, arranging two rows of grouting holes in a quincunx manner at a position 600mm away from the soil-facing side, and arranging the grouting holes in the quincunx manner at a distance of @800mm multiplied by 800mm in the middle of the pilot tunnel; in the stratum filled with soil and sand pebbles, the grouting pressure is preferably controlled to be 1.0MPa, the rest of the stratum is preferably controlled to be 2MPa, the diffusion radius is 0.6m, and the distance between the end parts of grouting holes is 0.9 m.
And secondly, preparing cement paste and water glass paste by using the cement-water glass double-liquid grout respectively, pumping by using a double-liquid grouting pump, mixing in a mixer, and injecting into an engineering object after mixing.
Further optimizing, the cement-water glass double-liquid slurry is mixed according to the proportion of 1:0.6 between the cement slurry and the water glass slurry.
In the steps S1-S4, the thickness of the primary support is 0.35m, the thickness of the temporary support is 0.3m, the longitudinal distance between the grid steel frames is 0.8m, the main grid ribs, the truss ribs and the longitudinal connecting ribs are HRB400 steel bars, the rest are HPB300 steel bars, and the temporary middle partition wall is made of Q235b steel; the foot-locking anchor rod adopts DN32 multiplied by 2.75 steel welded pipe, the length is 2.5m, and the incident angle is 45 degrees.
In this embodiment, in the step S2, during the tunnel excavation supporting, when the clear distance between the primary supports is less than or equal to 1.8m, a 2m long DN32 small conduit needs to be drilled at one side of the backward excavated tunnel in the tunnel to be excavated in the previous stage, and filling and grouting are performed, and in the process of excavating the backward tunnel, the redundant small conduits are cut off and welded and fixed with the grid steel frame, and are also used as the pin-locking anchor pipes of the backward excavated tunnel.
Example 3
As shown in fig. 1-4, the method for constructing the disturbance sensitive stratum ultra-small clear distance large section group-hole parallel subway tunnel comprises the following steps:
s1, constructing a middle large-end-face tunnel, excavating and constructing the middle large-section tunnel by adopting a double-side-wall pilot tunnel method, constructing pilot holes 1 to 6 in a construction working face of the middle large-end-face tunnel in sequence, performing full-section deep-hole grouting on a deep-hole grouting reinforcement area before pilot hole excavation, supporting the construction working face through a grid steel frame, constructing each pilot hole by adopting an upper and lower step method, staggering the upper and lower steps by 4m, reserving core soil on the upper step, arranging two locking anchor pipes at arch feet of each step, and reliably welding the locking anchor rods with the grid steel frame, wherein the front and back staggering of each pilot hole is not less than 8 m;
s2, constructing a small clear distance tunnel, after completing S1 construction, symmetrically constructing the small clear distance tunnel at two sides of the tunnel constructed in the S1 step by adopting a step method, performing full-section deep hole grouting on a deep hole grouting reinforcement area before pilot tunnel excavation, supporting a construction working face through a grid steel frame, sealing a primary support into a ring in time, enabling the primary support to be spaced from a large-section tunnel pilot tunnel by not less than 8m, constructing by adopting an upper step method and a lower step method, staggering the upper step and the lower step by 4m, reserving core soil on the upper step, erecting the grid steel frame for supporting after the pilot tunnel excavation, and simultaneously arranging a foot locking anchor rod and spraying concrete for supporting and strengthening, wherein the foot locking anchor rod is reliably welded with the grid, and each pilot tunnel is staggered from front to back by not less than 8 m;
s3, standard section tunnel construction, after S2 construction is completed, an outermost standard section tunnel is symmetrically constructed and constructed outside the tunnel constructed and constructed in S2 by adopting a step method, full-section deep hole grouting is firstly carried out on a deep hole grouting reinforcement area before pilot tunnel excavation, a construction working face is supported through a grid steel frame, a primary support is sealed into a ring in time and is spaced from adjacent tunnel pilot tunnels by 8m, then construction is carried out by adopting an upper step method and a lower step method, the upper step and the lower step are staggered by 4m, core soil is reserved on the upper step, the grid steel frame is erected after pilot tunnel excavation, foot locking anchor rods are arranged and concrete injection support reinforcement is carried out, wherein the foot locking anchor rods are reliably welded with the grids, and the front and back staggering of each pilot tunnel is not less than 8 m;
s4, constructing an outer side large-end-face tunnel, and after the construction of the S3 step is completed, constructing an outermost side large-section tunnel by a CRD method, wherein full-section deep hole grouting is firstly carried out on a deep hole grouting reinforcement area before pilot tunnel excavation, a construction working face is supported by a grid steel frame, a primary support is timely sealed to form a ring and is spaced by 8m from an adjacent tunnel pilot tunnel, then construction is carried out by an upper step and a lower step, the upper step and the lower step are staggered by 4.5m, core soil is reserved on the upper step, two foot-locking anchor pipes are arranged at each step arch foot, foot-locking anchor rods are reliably welded with the grid, and each pilot tunnel is staggered by not less than 8m from front to back;
and S5, secondarily reinforcing the tunnel group, after the construction of the S4 step is completed, performing secondary lining construction after the construction is completely completed in the steps from S1 to S4 and the stratum deformation tends to be stable, in the construction of the secondary lining with the large section by the double-side-wall pit guide method, only chiseling the surface concrete of the primary support during the primary support dismantling operation, performing waterproof treatment on the grid steel frame, and completing the integral construction of the tunnel after the secondary reinforcement is completed, wherein the dismantling length is not more than 6m during the primary support dismantling.
In the steps S1-S4, when full-section deep hole grouting is performed on a deep hole grouting reinforcement area before pilot tunnel excavation, the grouting range is 3m outside an initial support profile, grout is cement-water-glass double-liquid grout, the grouting footage is 10m, the tunneling is 8m, and the tail end 2m is a grout stop wall for next grouting; hole sites need to be marked at grouting positions in deep hole grouting, hole site deviation of drilling is not more than 200mm, hole forming deflection rate is not more than 1%, deep hole grouting hole site arrangement needs to be according to grouting ranges and tunnel excavation forms, horizontal channels and interval undercut tunnel full-face grouting holes are arranged, after deep hole grouting reinforcement of each pilot tunnel, a leading small guide pipe needs to be arranged within 120-degree range of a vault before pilot tunnel excavation, the small guide pipe is a DN32 multiplied by 2.75 steel welded pipe, the length is 2.5m, the circumferential spacing is 0.3m, the longitudinal spacing is 1m, the small guide pipe is only used for filling grouting, and grout is selected; in the process of manufacturing the small guide pipe, the steel pipe is cut into the required length, one end of the steel pipe is made into a conical shape with the length of 300mm, a hole is not formed in the range of 1000mm at the tail end, and slurry overflow holes with the diameter of 7mm are distributed in the rest part of the steel pipe at intervals of 180mm in a quincunx shape.
Further, during grouting operation of the grouting holes, the grouting method comprises the following steps:
firstly, excavating a pilot tunnel close to the position of the soil-facing side, arranging two rows of grouting holes in a quincunx manner at a position 550mm away from the soil-facing side, and arranging the grouting holes in the quincunx manner at a distance of @800mm multiplied by 800mm in the middle of the pilot tunnel; in the stratum filled with soil and sand pebbles, the grouting pressure is preferably controlled to be 0.8MPa, the rest of the stratum is preferably controlled to be 1.5MPa, the diffusion radius is 0.5m, and the distance between the end parts of grouting holes is 0.8 m.
And secondly, preparing cement paste and water glass paste by using the cement-water glass double-liquid grout respectively, pumping by using a double-liquid grouting pump, mixing in a mixer, and injecting into an engineering object after mixing.
Further, the cement-water glass double-liquid slurry is mixed according to the proportion of 1:0.8 of cement slurry and water glass slurry.
Further, in the steps S1-S4, the thickness of the primary support is 0.35m, the thickness of the temporary support is 0.3m, the longitudinal spacing of the grid steel frames is 0.5m, the main grid ribs, the truss ribs and the longitudinal connecting ribs are HRB400 steel bars, the rest are HPB300 steel bars, and the temporary middle partition wall adopts Q235b steel; the foot-locking anchor rod adopts DN32 multiplied by 2.75 steel welded pipe, the length is 2.5m, and the incident angle is 45 degrees.
Further, in the step S2, during tunnel excavation supporting, when the clear distance between the primary supports is less than or equal to 1.8m, a 2m long DN32 small conduit needs to be drilled at one side of the backward excavated tunnel in the tunnel excavated in the previous period, and filling and grouting are performed, and in the process of excavating the backward tunnel, the redundant small conduit is cut off and welded and fixed with the grid steel frame, and is also used as a lock pin anchor pipe of the backward excavated tunnel.
Example 4
As shown in fig. 1-4, the method for constructing the disturbance sensitive stratum ultra-small clear distance large section group-hole parallel subway tunnel comprises the following steps:
and S1, constructing the middle large-end-face tunnel, excavating the middle large-section tunnel by adopting a double-side-wall pilot tunnel method, and sequentially constructing pilot tunnels 1 to 6. And (3) performing full-face deep hole grouting on the deep hole grouting reinforcement area 15 before pilot tunnel excavation, wherein the grouting range is 3m outside the primary support profile, the grout is cement-water-glass double-liquid grout, the grouting footage is 10m, the tunneling is 8m, and the tail end 2m is a grout stop wall for next grouting. A leading small guide pipe 14 is arranged, the specification of the small guide pipe is DN32 multiplied by 2.75 steel welding pipes, the length is 2.5m, the circumferential distance is 0.3m, the longitudinal distance is 1m, the small guide pipe is only used for filling and grouting, and the grout is selected from cement paste.
Construction of each pilot hole by a double-side-wall pilot tunnel method is carried out by an upper step and a lower step, the upper step and the lower step are staggered by 3-5 m, core soil is reserved on the upper step, a grid steel frame is erected in time after the pilot holes are excavated, a foot-locking anchor rod 17 is arranged and concrete is sprayed, the thickness of a primary support 19 of a large-section tunnel is 0.35m, the thickness of a temporary support 18 is 0.3m, the longitudinal distance between grid steel frames is 0.5m, grid main ribs, truss ribs and longitudinal connecting ribs are HRB400 steel bars, the rest are HPB300 steel bars, a temporary middle partition wall is made of Q235b steel, foot-locking anchor rods 17 are made of DN32 multiplied by 2.75 steel welding pipes, the length is 2.5m, the incident angle is 45 degrees, and the foot-locking anchor rods are reliably welded with grids, and the front and the rear of each pilot hole are staggered by not less than 8 m.
And S2, constructing the small clear distance tunnel, and symmetrically constructing the small clear distance tunnels 7 and 8 on two sides of the large section by adopting a step method. And (3) performing full-face deep hole grouting on the deep hole grouting reinforcement area 15 before pilot tunnel excavation, wherein the grouting range is 3m outside the primary support profile, the grout is cement-water-glass double-liquid grout, the grouting footage is 10m, the tunneling is 8m, and the tail end 2m is a grout stop wall for next grouting. A leading small guide pipe 14 is arranged, the specification of the small guide pipe is DN32 multiplied by 2.75 steel welding pipes, the length is 2.5m, the circumferential distance is 0.3m, the longitudinal distance is 1m, the small guide pipe is only used for filling and grouting, and the grout is selected from cement paste.
The method comprises the steps of constructing the upper step and the lower step, staggering the upper step and the lower step by 3-5 m, reserving core soil on the upper step, erecting a grid steel frame in time after excavating a pilot tunnel, setting a foot-locking anchor rod 17 and spraying concrete, wherein the thickness of a primary tunnel support 22 is 0.3m, the longitudinal distance between grid steel frames is 0.5m, main grid ribs, truss ribs and longitudinal connecting ribs are HRB400 steel bars, the rest are HPB300 steel bars, the foot-locking anchor rod 17 is a DN32 multiplied by 2.75 steel welded pipe, the length is 2.5m, the incident angle is 45 degrees, the foot-locking anchor rod and the grid are reliably welded, and the front and the back of each pilot tunnel are staggered by not less than 8 m.
And S3, constructing the standard section tunnel, and constructing the outermost standard section tunnel 9 by adopting a step method. And (3) carrying out full-face deep hole grouting on the deep hole grouting reinforcement area 15 before pilot tunnel excavation, wherein the grouting range is 3m outside the primary support profile, the grout is cement-water-glass double-grout, the grouting footage is 10m, the tunneling is 8m, and the tail end is 2m and is a grout stop wall for next grouting. A leading small guide pipe 14 is arranged, the specification of the small guide pipe is DN32 multiplied by 2.75 steel welding pipes, the length is 2.5m, the circumferential distance is 0.3m, the longitudinal distance is 1m, the small guide pipe is only used for filling and grouting, and the grout is selected from cement paste.
The method comprises the steps of constructing the upper step and the lower step, staggering the upper step and the lower step by 3-5 m, reserving core soil on the upper step, erecting a grid steel frame in time after excavating a pilot tunnel, setting a foot-locking anchor rod 17 and spraying concrete, wherein the thickness of a primary tunnel support 23 is 0.3m, the longitudinal distance between grid steel frames is 0.5m, main grid ribs, truss ribs and longitudinal connecting ribs are HRB400 steel bars, the rest are HPB300 steel bars, the foot-locking anchor rod 17 is a DN32 multiplied by 2.75 steel welded pipe, the length is 2.5m, the incident angle is 45 degrees, the foot-locking anchor rod and the grid are reliably welded, and the front and the back of each pilot tunnel are staggered by not less than 8 m.
And S4, constructing the large end face tunnel on the outer side, constructing the large cross-section tunnel on the outermost side by adopting a CRD method, and sequentially excavating the pilot tunnels from 10 to 13. And (3) carrying out full-face deep hole grouting on the deep hole grouting reinforcement area 15 before pilot tunnel excavation, wherein the grouting range is 3m outside the primary support profile, the grout is cement-water-glass double-grout, the grouting footage is 10m, the tunneling is 8m, and the tail end is 2m and is a grout stop wall for next grouting. A leading small guide pipe 14 is arranged, the specification of the small guide pipe is DN32 multiplied by 2.75 steel welding pipes, the length is 2.5m, the circumferential distance is 0.3m, the longitudinal distance is 1m, the small guide pipe is only used for filling and grouting, and the grout is selected from cement paste.
The tunnel is constructed by the CRD method, the thickness of a primary support 20 is 0.35m, the thickness of a temporary support is 0.3m, the longitudinal distance between grid steel frames is 0.5m, grid main reinforcements, truss reinforcements and longitudinal connecting reinforcements are HRB400 reinforcements, the rest are HPB300 reinforcements, and a temporary middle partition wall is made of Q235b steel. Each pilot tunnel is constructed by an upper step and a lower step, the upper step and the lower step are staggered by 3-5 m, core soil is reserved on the upper step, two foot-locking anchor pipes 17 are arranged at the arch foot of each step, foot-locking anchor pipes are DN32 multiplied by 2.75 steel welding pipes, the length is 2.5m, the incident angle is 45 degrees, the foot-locking anchor pipes are reliably welded with grids, and the front and the back of each pilot tunnel are staggered by not less than 8 m.
The clear distance between the primary support 20 and the primary support 22 is less than or equal to 1.8m, 2m long DN32 small guide pipes 16 are arranged on one side of the backward excavated tunnel in the tunnel excavated in advance and used for filling and grouting, the guide hole 10 cuts off the redundant small guide pipes 16 in the excavation process, and the guide hole is welded and fixed with a grid steel frame and also used as a locking pin anchor pipe of the primary support of the guide hole 10.
And S5, secondary reinforcing of the tunnel group, and constructing the secondary linings 24 to 28 of the group tunnel after the stratum deformation tends to be stable. Temporary supports 18 are reserved in the construction of the double-side-wall pit-guiding method large-section secondary lining 24, only surface concrete is chiseled off, waterproof treatment is carried out on the positions where the section steel penetrates through the secondary lining, and the temporary supports are removed after the construction of the secondary lining is completed. During the construction of the large-section secondary lining 28 by the CRD method, the removal length of the temporary support 21 is required to be paid attention, the removal length of the support is required not to exceed 6m each time, and the construction of a skip silo can be adopted.
The method effectively solves the problems that in a disturbance sensitive stratum excavated in a city, underground excavation construction is carried out on a group of ultra-small clear distance large section holes parallel to a subway tunnel, and the excavation construction of a rear hole easily causes overlarge deformation of a primary support of a front hole and cracking of a secondary lining, and the like.
The foregoing shows and describes the general principles and broad features of the present invention and advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are given by way of illustration of the principles of the present invention, but that various changes and modifications may be made without departing from the spirit and scope of the invention, and such changes and modifications are within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (6)
1. The construction method of the disturbance sensitive stratum ultra-small clear distance large section group-hole parallel subway tunnel is characterized by comprising the following steps of:
s1, constructing a middle large-end-face tunnel, excavating and constructing the middle large-section tunnel by adopting a double-side-wall pilot tunnel method, constructing pilot holes in a construction working face of the middle large-end-face tunnel in sequence, performing full-section deep-hole grouting on a deep-hole grouting reinforcement area before pilot hole excavation, supporting the construction working face through a grid steel frame, constructing each pilot hole by adopting an upper and lower step method, staggering the upper and lower steps for 3-5 m, reserving core soil on the upper step, drilling two locking anchor pipes at each step arch foot, reliably welding the locking anchor rods with the grid steel frame, and staggering the front and back of each pilot hole for not less than 8 m;
s2, constructing a small clear distance tunnel, after completing S1 construction, symmetrically constructing the small clear distance tunnel on two sides of the tunnel constructed in the S1 step by adopting a step method, performing full-section deep hole grouting on a deep hole grouting reinforcement area before pilot tunnel excavation, supporting a construction working face through a grid steel frame, sealing a primary support to form a ring in time, enabling the primary support to be spaced from a large-section tunnel pilot tunnel by not less than 8m, constructing by adopting an upper step method and a lower step method, staggering the upper step and the lower step by 3-5 m, reserving core soil on the upper step, erecting the grid steel frame for supporting after pilot tunnel excavation, and simultaneously arranging a foot locking anchor rod and spraying concrete for supporting and strengthening, wherein the foot locking anchor rod is reliably welded with the grid, and each pilot tunnel is staggered from front to back by not less than 8 m;
s3, standard section tunnel construction, after S2 construction is completed, an outermost standard section tunnel is symmetrically constructed on the outer side of the tunnel constructed in S2 by adopting a step method, full-section deep hole grouting is firstly carried out on a deep hole grouting reinforcement area before pilot tunnel excavation, a construction working face is supported through a grid steel frame, a primary support is sealed into a ring in time and is spaced from adjacent tunnel pilot tunnels by 8m, then construction is carried out by adopting an upper step method and a lower step method, the upper step and the lower step are staggered by 3-5 m, core soil is reserved on the upper step, the grid steel frame is erected after pilot tunnel excavation, foot locking anchor rods are arranged and concrete spraying support reinforcement is carried out, the foot locking anchor rods are reliably welded with the grids, and the front and back staggering of each pilot tunnel is not less than 8 m;
s4, constructing an outer side large-end-face tunnel, and after completing construction in the S3 step, constructing an outermost side large-section tunnel by using a CRD method, wherein full-section deep-hole grouting is firstly performed on a deep-hole grouting reinforcement area before pilot tunnel excavation, a construction working face is supported by a grid steel frame, a primary support is sealed in time to form a ring and is spaced by 8m from an adjacent tunnel pilot tunnel, then construction is performed by using an upper-lower step method, the upper step and the lower step are staggered by 3-5 m, core soil is reserved on the upper step, two locking anchor pipes are arranged at each step arch foot, the locking anchor rods are reliably welded with the grid, and the front-back staggering of each pilot tunnel is not less than 8 m;
and S5, secondarily reinforcing the tunnel group, performing secondary lining construction after the construction of the step S4 is completed, completing the construction in all the steps S1 to S4, and performing secondary lining construction after the stratum deformation tends to be stable, in the large-section secondary lining construction of the double-side-wall pit guiding method, only chiseling the surface concrete of the primary support during the primary support dismantling operation, performing waterproof treatment on the grid steel frame, and completing the integral construction of the tunnel after the secondary reinforcement is completed, wherein the dismantling length is not more than 6m each time during the primary support dismantling.
2. The construction method of the disturbance sensitive stratum ultra-small clear distance large section group-hole parallel subway tunnel according to claim 1, wherein in the step S1-S4, when full-section deep hole grouting is performed on the deep hole grouting reinforcement area before pilot tunnel excavation, the grouting range is 2-5 m outside the primary support profile, the grout is cement-water-glass double-liquid grout, the grouting footage is 10m, the tunneling is 8m, and the tail end 2m is a grout stop wall for next grouting; hole sites need to be marked at grouting positions in deep hole grouting, hole site deviation of drilling is not more than 200mm, hole forming deflection rate is not more than 1%, deep hole grouting hole site arrangement needs to be based on grouting ranges and tunnel excavation forms, transverse channels and interval undercut tunnel full-face grouting holes are arranged, leading small guide pipes need to be arranged within 120-degree range of a vault before pilot tunnel excavation after deep hole grouting reinforcement of each pilot tunnel, the small guide pipes are DN32 multiplied by 2.75 steel welded pipes, the length is 2-3 m, circumferential spacing is 0.1-0.5 m, longitudinal spacing is 0.5-1.5 m, the small guide pipes are only used for filling grouting, and grout is selected from cement paste; in the process of manufacturing the small guide pipe, the steel pipe is cut into required length, one end of the steel pipe is made into a cone shape with the length of 200-400 mm, no hole is formed in the range of 1000mm at the tail end, and slurry overflow holes with the diameter of 6-8 mm are distributed in a quincunx shape at intervals of 150-200 mm in the rest part.
3. The method for constructing the disturbance sensitive stratum ultra-small clear distance large section group-hole parallel subway tunnel according to claim 2, wherein the grouting operation of the grouting holes is performed according to the following steps:
firstly, excavating a pilot tunnel close to the position of the soil-facing side, arranging two rows of grouting holes in a quincunx manner at a position 400-600 mm away from the soil-facing side, and arranging the grouting holes in a quincunx manner at a distance of @800mm multiplied by 800mm in the middle of the pilot tunnel; in the soil-filled and sandy gravel stratum, the grouting pressure is preferably controlled to be 0.5-1.0 MPa, the rest of the stratum is preferably controlled to be 1-2 MPa, the diffusion radius is 0.4-0.6 m, and the distance between the end parts of grouting holes is 0.7-0.9 m;
and secondly, preparing cement paste and water glass paste by using the cement-water glass double-liquid slurry respectively, pumping by using a double-liquid grouting pump, mixing in a mixer, and injecting into an engineering object after mixing.
4. The construction method of the disturbance sensitive stratum ultra-small clear distance large section group-hole parallel subway tunnel according to claim 2 or 3, characterized in that the cement slurry and the water glass slurry are mixed according to a ratio of cement slurry to water glass slurry of 1: 1-1: 0.6.
5. The method for constructing the group-hole parallel subway tunnel with the ultra-small clear distance and the large cross section in the disturbance sensitive stratum according to claim 1, wherein in the step S1-S4, the thickness of the primary support is 0.35m, the thickness of the temporary support is 0.3m, the longitudinal distance between grid steel frames is 0.3-0.8 m, the main grid ribs, the truss ribs and the longitudinal connecting ribs are HRB400 steel bars, the rest are HPB300 steel bars, and the temporary middle partition wall adopts Q235b steel; the foot-locking anchor rod adopts DN32 multiplied by 2.75 steel welded pipe, the length is 2.5m, and the incident angle is 45 degrees.
6. The method for constructing the group tunnel parallel subway tunnel with the ultra-small clear distance and the large cross section in the disturbance sensitive stratum according to claim 1, wherein in the step S2, during the tunnel excavation supporting, when the clear distance between the primary supports is less than or equal to 1.8m, a 2m long DN32 small guide pipe needs to be arranged on one side of the backward excavation tunnel in the early excavation tunnel, filling grouting is carried out, redundant small guide pipes are cut off in the process of excavating the backward tunnel, the extra small guide pipes are welded and fixed with grid steel frames, and the extra small guide pipes also serve as foot locking anchor pipes of the backward excavation tunnel.
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