CN113565513A - Upper and lower step reserved core soil excavation method for tunnel excavation - Google Patents
Upper and lower step reserved core soil excavation method for tunnel excavation Download PDFInfo
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- CN113565513A CN113565513A CN202110790464.7A CN202110790464A CN113565513A CN 113565513 A CN113565513 A CN 113565513A CN 202110790464 A CN202110790464 A CN 202110790464A CN 113565513 A CN113565513 A CN 113565513A
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- 238000009412 basement excavation Methods 0.000 title claims abstract description 187
- 239000002689 soil Substances 0.000 title claims abstract description 95
- 238000000034 method Methods 0.000 title claims abstract description 34
- 239000011435 rock Substances 0.000 claims abstract description 36
- 238000010276 construction Methods 0.000 claims abstract description 24
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 15
- 239000010959 steel Substances 0.000 claims abstract description 15
- 238000013461 design Methods 0.000 claims description 5
- 238000001746 injection moulding Methods 0.000 claims description 3
- 239000011378 shotcrete Substances 0.000 claims description 3
- 238000006073 displacement reaction Methods 0.000 abstract description 3
- 239000004567 concrete Substances 0.000 description 12
- 238000005422 blasting Methods 0.000 description 7
- 230000035939 shock Effects 0.000 description 4
- 238000012544 monitoring process Methods 0.000 description 3
- 238000005507 spraying Methods 0.000 description 3
- 238000005034 decoration Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 230000005641 tunneling Effects 0.000 description 2
- 230000002159 abnormal effect Effects 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 238000005474 detonation Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000002360 explosive Substances 0.000 description 1
- 238000001125 extrusion Methods 0.000 description 1
- 239000004746 geotextile Substances 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 230000002787 reinforcement Effects 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 239000004575 stone Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
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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
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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
- E21D11/003—Linings or provisions thereon, specially adapted for traffic tunnels, e.g. with built-in cleaning devices
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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
- E21D11/38—Waterproofing; Heat insulating; Soundproofing; Electric insulating
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- Mining & Mineral Resources (AREA)
- Structural Engineering (AREA)
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- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
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- Civil Engineering (AREA)
- Environmental & Geological Engineering (AREA)
- Lining And Supports For Tunnels (AREA)
Abstract
The embodiment of the application provides an upper step and lower step reserved core soil excavation method for tunnel excavation, and relates to the technical field of tunnel construction, the technical scheme of the application adopts an upper step annular pilot tunnel reserved core soil body to support a tunnel face, and instability of the tunnel face is effectively prevented; the core soil body in the middle of the lower step is excavated in advance, and soil bodies on two side wall parts are reserved, so that the stress area of the arch springing can be effectively ensured, and inward displacement of the steel frame under stress can be prevented; the method is particularly suitable for the construction of tunnels with general soil texture or weak surrounding rocks which are easy to collapse and large sections, such as IV-grade or V-grade surrounding rock large-section tunnels.
Description
Technical Field
The invention relates to the technical field of tunnel construction, in particular to an excavation method of upper and lower step reserved core soil for tunnel excavation.
Background
When the tunnel passes through the layered soft rock stratum, the deformation characteristic of the surrounding rock and the mechanical property of the supporting structure have obvious asymmetric characteristics. Due to the fact that the weak surrounding rock is low in strength and poor in self-supporting capacity, the tunnel supporting structure can bear large load, and the tunnel can be damaged by extrusion. Therefore, how to adopt a reasonable supporting mode and a construction method for the tunnel penetrating through the layered soft rock stratum has important significance for the safety guarantee of the tunnel structure.
Disclosure of Invention
In view of the above problems, an object of the present invention is to provide an excavation method of upper and lower steps reserved core soil for tunnel excavation, which is suitable for tunnel construction of general soil quality or weak surrounding rock which is easy to collapse and large section, improves stability of a tunnel working surface, effectively controls deformation of the surrounding rock, and ensures safe construction of engineering.
The upper and lower step reserved core soil excavation method for tunnel excavation provided by the embodiment of the invention comprises the following steps:
(1) the method comprises the steps of dividing a tunnel section into an upper step part and a lower step part, wherein the upper step part comprises an annular guide pit excavation area and an upper step core soil excavation area, the lower step part comprises a first side wall excavation area, a second side wall excavation area and a lower step core soil excavation area, the section shape of the upper step core soil excavation area is trapezoidal, the section shape of the lower step core soil excavation area is inverted trapezoidal, and the sum of the section areas of the upper step core soil excavation area and the lower step core soil excavation area is not less than 50% of the section area of the tunnel;
(2) under the condition of advance support, excavating the annular guide pit excavation area, constructing an upper step primary support, and excavating the upper step core soil excavation area;
(3) excavating the lower step core soil excavation area, then excavating the first side wall portion excavation area and the second side wall portion excavation area in a staggered mode, and timely performing primary support on the side wall portions;
(4) excavating an inverted arch, and constructing an initial inverted arch support to form a ring with the existing support in a closed manner;
(5) the inverted arch is poured and laid with a waterproof board in advance, and a template trolley is used for injection molding for secondary lining at one time;
(6) and (5) circulating according to the steps (1) to (5) until the tunnel is penetrated.
Further, in the step (2), the length of the annular guide pit excavation region is 10-15 m.
Further, the length of the reserved core soil body in the upper step core soil excavation area is 5-10 m, and the length of the reserved core soil body in the lower step core soil excavation area is 5-10 m.
Further, in the step (3), the working surface of the excavation area of the front side wall portion is advanced by 2 to 3m from the working surface of the excavation area of the rear side wall portion.
Further, in the step (3), the tunnel face of the lower step core soil excavation area is advanced by 10 to 15m from the tunnel face of the advanced side wall portion excavation area.
Further, the secondary lining lags behind the tunnel face of the excavated area of the rear sidewall by more than 20 m.
Furthermore, in the steps (2) and (3), the excavation depth is not more than 2 steel arch frame distances in each cycle.
Further, the distance between the upward arch and the tunnel face of the upper step is not more than 30 m.
Further, in the step (3), after the strength of the shotcrete of the preliminary bracing of the upper step reaches 70% of the design strength, the lower step excavation is performed.
Further, the first side wall part excavation area is one side, far away from the rock pillar in the double-hole tunnel, of the lower step part, and the second side wall part excavation area is one side, close to the rock pillar in the double-hole tunnel, of the lower step part;
in step (3), the staggering excavation of the first side wall excavation area and the second side wall excavation area and timely sidewall primary support are performed, and the method includes:
firstly excavating the excavation area of the first side wall part, and constructing primary support of the first side wall part;
and excavating the second side wall excavation area, and constructing primary support of the second side wall.
Furthermore, the tunnel face of the backward tunnel lags behind the tunnel face of the forward tunnel by not less than 35 m.
Furthermore, the tunnel face of the backward tunnel is advanced by not less than 20m than the secondary lining of the forward tunnel.
According to the upper and lower step reserved core soil excavation method for tunnel excavation, provided by the embodiment of the application, the upper step annular pilot tunnel is adopted to reserve a core soil body to support the tunnel face, so that the instability of the tunnel face is effectively prevented; the core soil body in the middle of the lower step is excavated in advance, and soil bodies on two side wall parts are reserved, so that the stress area of the arch springing can be effectively ensured, and inward displacement of the steel frame under stress can be prevented; the method is particularly suitable for the construction of tunnels with general soil texture or weak surrounding rocks which are easy to collapse and large sections, such as IV-grade or V-grade surrounding rock large-section tunnels.
Drawings
In order to more clearly illustrate the technical solution of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic diagram of an excavation section of upper and lower step reserved core soil for tunnel excavation according to an embodiment of the present invention;
fig. 2 is a schematic flow chart of an excavation method of upper and lower step reserved core soil for tunnel excavation according to an embodiment of the present invention;
fig. 3 is an excavation plan view of upper and lower step reserved core soil for tunnel excavation according to an embodiment of the present invention;
fig. 4 is a plan view of a small clear distance double-hole tunnel excavation provided by an embodiment of the invention.
Wherein the figures include the following reference numerals:
1. an upper step portion; 2. a lower step portion; 3. an inverted arch; 11. an annular guide pit excavation area; 12. excavating a core soil excavation area of the upper step; 11a, a top region; 11b and 11c, both side regions; 21. excavating an area by using lower step core soil; 22a, a first side wall excavation area; 22b, second side wall excavation areas; I. advance support; II. Primary support of arch parts; III, primary support of a first side wall part; IV, primary support of a second side wall part; v, primary support of an inverted arch; VI, secondary lining.
Detailed Description
It will be understood by those of ordinary skill in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
The technical solutions in the embodiments of the present application will be described clearly and completely with reference to the drawings in the embodiments of the present application, wherein the same or similar reference numerals refer to the same or similar elements or elements with the same or similar functions throughout. It is to be understood that the embodiments described are only a few embodiments of the present application and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
Referring to fig. 1 to 3, in the excavation method of the upper and lower steps reserved core soil for tunnel excavation according to the embodiment of the present application, an upper step portion 1 and a lower step portion 2 are formed on an excavation working surface;
annular excavation is carried out on the upper step part 1 to form an upper step core soil excavation area 12; specifically, before tunnel excavation, advance supports I are constructed along the design position outside the tunnel excavation contour line: installing an arch part phi 22 advanced cartridge anchor rod, setting the circumferential distance to be 40cm, advancing small conduit grouting pre-support, fully filling a soil body gap, forming a bearing arch with certain strength around the tunnel, improving the mechanical properties of rock soil and structure, so as to control excavation loosening, collapse and settlement and enhance the self-stability capability of surrounding rock; during excavation, an air pick or a single-arm tunneling machine is adopted to excavate the annular guide pit excavation area 11, so that the construction safety and effectiveness are ensured without collapse; after the annular guide pit excavation area 11 is excavated, arch springing and instability along the longitudinal tunnel face of the tunnel are caused by stress release of surrounding rocks, the upper step core soil excavation area 12 lags behind the annular guide pit excavation area by 113-5 m for excavation, so that a reserved core soil body is utilized to prop up a working face, arch sinking is reduced, the construction safety of an upper step is ensured, and the reserved core soil body can be further utilized as an operation platform for constructing an arch initial support II; and (3) timely applying a primary support II after the annular excavation is finished: installing an I18 steel arch frame, hanging an 8 phi steel bar mesh, installing a phi 22 cartridge anchor rod and spraying C25 concrete; under the protection of the arch primary support II, in order to accelerate the progress, an excavator or a single-arm tunneling machine is preferably adopted to excavate the upper step core soil excavation area 12 and the lower step part 2;
excavating the middle part of the lower step part 2 towards the depth direction to form a lower step core soil excavation area 21 and a first side wall part excavation area 22a and a second side wall part excavation area 22b which are positioned at two sides of the lower step core soil excavation area 21; specifically, the end surface of the lower step core soil excavation region 21 may be set as a slope surface, so that mechanical equipment (e.g., an excavator and the like) can enter the upper step portion 1 through the slope surface to perform excavation work.
During specific construction, surface subsidence is strictly controlled according to monitoring and measuring data, the circulating excavation footage is reduced, the distance between every two steel frames is not more than 0.5-1 m, the sectional area and the size of the core soil of the upper step and the lower step meet the requirement of stability of an excavation surface, and the sectional area is not lower than 50% of the excavation sectional area.
The excavation method of the upper and lower steps reserved core soil for tunnel excavation is suitable for construction of general soil or weak surrounding rocks which are easy to collapse and tunnels with large sections, such as IV-level or V-level surrounding rock large-section tunnels, and comprises the following steps:
(1) the method comprises the steps of dividing a tunnel section into an upper step part 1 and a lower step part 2, wherein the upper step part 1 comprises an annular guide pit excavation area 11 and an upper step core soil excavation area 12, and the lower step part 2 comprises a first side wall part excavation area 22a, a second side wall part excavation area 22b and a lower step core soil excavation area 21;
the section of the upper step core soil excavation area 12 is trapezoidal, and the section of the lower step core soil excavation area 21 is inverted trapezoidal, so that the pressure of a soil body on a tunnel face is effectively balanced, the stress release is weakened, and the range of a face empty face is reduced, so that the stability of surrounding rocks on the tunnel face is ensured, and abnormal conditions such as collapse cannot occur; the sum of the section areas of the upper step core soil excavation region 12 and the lower step core soil excavation region 21 is not less than 50% of the section area of the tunnel, so that the stability of an excavation working surface is ensured;
(2) under the condition of an advance support I, excavating the annular guide pit excavation area 11, constructing an upper step primary support, and excavating the upper step core soil excavation area 12;
specifically, the annular guide pit excavation area 11 can be divided into a top area 11a and two side areas 11b and 11c for alternate excavation, disturbance caused by large-area earthwork excavation of weak surrounding rock is reduced, the rock mass is fully protected, an arch part primary support II is timely implemented, the deformation of the rock mass is limited by fully utilizing a support structure, and the rock mass is ensured not to be excessively loosened to lose or reduce the bearing capacity of the rock mass; excavating the upper step core soil excavation area 12 after the annular guide pit excavation area 11 is excavated and supported for 3-5 m; further, the annular guide pit excavation area 11 and the upper step core soil excavation area 12 are staggered from front to back by 3-5 m for parallel operation until the excavation length of the annular guide pit excavation area 11 reaches a first preset length and the length of a core soil body of the upper step core soil excavation area 12 is reserved to be a second preset length; preferably, the first preset length is 10-15 m, and the second preset length is 5-10 m;
(3) excavating the lower step core soil excavation area 21, then excavating the first side wall excavation area 22a and the second side wall excavation area 22b in a staggered mode, and timely performing primary support on the side wall;
preferably, after the strength of the sprayed concrete of the upper step primary support reaches 70% of the design strength, the lower step core soil excavation area 21 is excavated.
Further, after the lower step core soil excavation area 21 is excavated for 3-5 m, the first side wall excavation area 22a is excavated for 3-5 m, a first side wall primary support III is applied, the second side wall excavation area 22b is excavated for 3-5 m, a second side wall primary support IV is applied, or the second side wall excavation area 22b is excavated for 3-5 m, a second side wall primary support IV is applied, the first side wall excavation area 22a 3-5 m is excavated, and a first side wall primary support III is applied, and similarly, the excavation areas of the lower step part 2 are parallelly staggered by 3-5 m; preferably, after each excavation, the tunnel face of the lower step core soil excavation area 21 is 10-15 m ahead of the tunnel face of the front side wall excavation area, and the tunnel face of the front side wall excavation area is 2-3 m ahead of the tunnel face of the rear side wall excavation area.
(4) Excavating an inverted arch 3, and constructing an inverted arch primary support V to form a ring with the existing support in a closed manner;
preferably, the distance between the inverted arch 3 and the tunnel face of the upper step is not more than 30 m. The inverted arch 3 is excavated by adopting loose blasting and matching with an excavator, a steel trestle is built after the excavation is finished, and then the lower part of the inverted arch is constructed; then, C20 spray concrete construction is carried out: primarily spraying 4cm thick concrete, and re-spraying the concrete to the designed thickness after the I20b inverted arch steel arch construction is finished; when the steel arch is installed, the inverted arch steel arch is connected with the steel arches at the arch feet of the left side wall and the right side wall, and the connecting steel plates are adopted for welding according to the design requirements, so that the closed ring forming effect is really realized.
(5) The inverted arch is poured and laid with a waterproof board in advance, and a template trolley is used for injection molding of a secondary lining VI in one step;
the inverted arch advanced pouring construction process comprises the following steps: firstly, installing an inverted arch template; pouring C30 concrete; finally, backfilling an inverted arch; the concrete pouring is symmetrically poured from the center of the inverted arch to two sides and is finished at one time, the concrete is vibrated by an inserted vibrating rod, the vibrating rod is vibrated while pouring, the vibrating rod is vertical during vibrating and is driven into and out slowly, vibrating points are uniformly distributed in a surface way and are away from a template for a certain distance, and the concrete is vibrated until the concrete does not bubble or sink and the surface begins to be pulped; the inverted arch backfill adopts C15 stone concrete, the inverted arch fills the transverse two-side vertical steel die, the thickness, the elevation and the flatness of the cushion layer are strictly controlled, the backfill is prevented from invading the pavement part, the filled concrete allows pedestrians to pass after reaching the strength of 5Mpa, and the vehicles can be allowed to pass after reaching 100% of the designed strength.
And further, laying geotextile and waterproof boards, performing secondary lining VI construction, and performing one-step pouring of the arch wall lining by using a lining template trolley. Preferably, the secondary lining lags behind the tunnel face of the excavated area of the trailing side wall portion by more than 20 m.
Preferably, the distance between the secondary lining and the tunnel face of the upper step is reasonably controlled according to the monitoring and measuring data; for example, in the construction of IV-level surrounding rock tunnels, the distance between the secondary lining and the tunnel face of the upper step is not more than 90 m; in the construction of a V-level surrounding rock tunnel, the distance between a secondary lining and the tunnel face of an upper step is not more than 70 m; in the excavation of the opening and the shallow buried section, the distance between the secondary lining and the tunnel face of the upper step is not more than 50 m; certainly, the secondary lining should be followed up in time when the geological conditions are poor, and the secondary lining needs to be set according to actual application and is within the protection scope of the invention.
(6) And (5) circulating according to the steps (1) to (5) until the tunnel is penetrated.
The upper and lower step reserved core soil excavation method for tunnel excavation provided by the embodiment adopts the upper step annular pilot tunnel reserved core soil body to support the tunnel face, so that the instability of the tunnel face is effectively prevented; the core soil body in the middle of the lower step is excavated in advance, and soil bodies on two side wall parts are reserved, so that the stress area of the arch springing can be effectively ensured, and inward displacement of the steel frame under stress can be prevented; the method is particularly suitable for the construction of tunnels with general soil texture or weak surrounding rocks which are easy to collapse and large sections, such as IV-grade or V-grade surrounding rock large-section tunnels.
Referring to fig. 4, the method for excavating the upper and lower steps of the reserved core soil for tunnel excavation according to the above embodiment is applied to the construction of a small-clear-distance double-hole tunnel; specifically, because the width of a middle rock column of the small-clear-distance double-tunnel is small, the blasting vibration of the current excavated tunnel has great influence on the adjacent tunnel, the blasting explosive quantity of each section of the tunnel is strictly controlled, so that the vibration speed is controlled within 15cm/s, and in order to avoid the superposition of vibration waves, differential control blasting is adopted, and the detonation time of each section is determined according to the vibration test result.
Specifically, a small conduit is applied to the middle rock pillar before the tunnel is excavated, and grouting reinforcement is carried out; when grouting reaches a certain strength, excavating the advanced tunnel; the backward tunnel is excavated with the upper step after the backward tunnel falls to the bottom, the tunnel face of the backward tunnel lags behind the tunnel face of the forward tunnel by not less than 35m during excavation, and the prestress counter-pulling anchor rod of the rock pillar is installed during excavation and support of the upper step of the backward tunnel.
Preferably, in order to effectively reduce the damage of the blasting of the backward tunnel to the lining of the forward tunnel, the tunnel face of the backward tunnel is advanced by not less than 20m compared with the secondary lining of the forward tunnel.
Preferably, in order to minimize disturbance to the rock pillar during the excavation of the currently excavated tunnel, when the lower step is excavated, the step of excavating the first side wall excavation area 22a and the second side wall excavation area 22b in a staggered manner and applying a preliminary support for the side wall is performed in time, the method includes:
excavating the first side wall excavation area 22a in advance, and constructing a first side wall primary support;
excavating the second side wall excavation area 22b in a backward mode, and constructing primary support of the second side wall; the first side wall part excavation area is one side of the lower step part far away from the rock pillar in the double-hole tunnel, and the second side wall part excavation area is one side of the lower step part close to the rock pillar in the double-hole tunnel.
The embodiment aims at the small-clearance double-tunnel exit shock absorption, the maximum critical shock speed of the blasting shock of the current tunnel to the adjacent tunnel is strictly controlled within 15cm/s, the lagging of the tunnel face of the backward tunnel to the tunnel face of the first tunnel is controlled to be not less than 35m according to the monitoring and measuring data, the advancing of the tunnel face of the backward tunnel to the secondary lining of the first tunnel is not less than 20m, the damage of the blasting shock to the rock pillar and the concrete lining is effectively reduced, the construction safety is ensured, and the construction cost is reduced.
It should be understood that, although the steps in the flowcharts of the figures are shown in order as indicated by the arrows, the steps are not necessarily performed in order as indicated by the arrows. The steps are not performed in the exact order shown and may be performed in other orders unless explicitly stated herein. Moreover, at least a portion of the steps in the flow chart of the figure may include multiple sub-steps or multiple stages, which are not necessarily performed at the same time, but may be performed at different times, which are not necessarily performed in sequence, but may be performed alternately or alternately with other steps or at least a portion of the sub-steps or stages of other steps.
The foregoing is only a partial embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (12)
1. An excavation method of upper and lower step reserved core soil for tunnel excavation is characterized by comprising the following steps:
(1) the method comprises the steps of dividing a tunnel section into an upper step part and a lower step part, wherein the upper step part comprises an annular guide pit excavation area and an upper step core soil excavation area, the lower step part comprises a first side wall excavation area, a second side wall excavation area and a lower step core soil excavation area, the section shape of the upper step core soil excavation area is trapezoidal, the section shape of the lower step core soil excavation area is inverted trapezoidal, and the sum of the section areas of the upper step core soil excavation area and the lower step core soil excavation area is not less than 50% of the section area of the tunnel;
(2) under the condition of advance support, excavating the annular guide pit excavation area, constructing an upper step primary support, and excavating the upper step core soil excavation area;
(3) excavating the lower step core soil excavation area, then excavating the first side wall portion excavation area and the second side wall portion excavation area in a staggered mode, and timely performing primary support on the side wall portions;
(4) excavating an inverted arch, and constructing an initial inverted arch support to form a ring with the existing support in a closed manner;
(5) the inverted arch is poured and laid with a waterproof board in advance, and a template trolley is used for injection molding for secondary lining at one time;
(6) and (5) circulating according to the steps (1) to (5) until the tunnel is penetrated.
2. The excavation method of upper and lower steps reserved core soil for tunnel excavation according to claim 1, wherein in the step (2), the length of the annular guide pit excavation region is 10-15 m.
3. The upper and lower step reserved core soil excavation method for tunnel excavation according to claim 1, wherein the length of the reserved core soil body of the upper step core soil excavation area is 5 to 10m, and the length of the reserved core soil body of the lower step core soil excavation area is 5 to 10 m.
4. The upper and lower step pre-core soil excavation method for tunnel excavation according to claim 1, wherein in the step (3), the working face of the excavation area of the leading side wall portion is advanced by 2 to 3m from the working face of the excavation area of the trailing side wall portion.
5. The upper and lower step pre-prepared core soil excavation method for tunnel excavation according to claim 1, wherein in the step (3), the face surface of the lower step core soil excavation region is advanced by 10 to 15m from the face surface of the leading side wall portion excavation region.
6. The upper and lower step reserved core soil excavation method for tunnel excavation according to claim 1, wherein the secondary lining lags behind the tunnel face of the excavated area of the rear-row sidewall by more than 20 m.
7. The excavation method of upper and lower steps reserved core soil for tunnel excavation according to claim 1, wherein in the steps (2) and (3), the excavation footage per cycle is not more than 2 steel arch frame intervals.
8. The excavation method of upper and lower steps of reserved core soil for tunnel excavation according to claim 1, wherein the distance from the inverted arch to the tunnel face of the upper step is not more than 30 m.
9. The excavation method of upper and lower step prepared core soil for tunnel excavation according to claim 1, wherein in the step (3), the lower step excavation is performed after the strength of the upper step preliminary bracing shotcrete reaches 70% of the design strength.
10. The excavation method of upper and lower steps reserved core soil for tunnel excavation according to any one of claims 1 to 9, applied to construction of a small-clearance double-hole tunnel, wherein the first sidewall excavation area is a side of the lower step portion, which is far away from a rock pillar in the double-hole tunnel, and the second sidewall excavation area is a side of the lower step portion, which is close to the rock pillar in the double-hole tunnel;
in step (3), the staggering excavation of the first side wall excavation area and the second side wall excavation area and timely sidewall primary support are performed, and the method includes:
firstly excavating the excavation area of the first side wall part, and constructing primary support of the first side wall part;
and excavating the second side wall excavation area, and constructing primary support of the second side wall.
11. The upper and lower step reserved core soil excavation method for tunnel excavation according to claim 10, applied to construction of a small-clearance double-hole tunnel, wherein the heading face of the following tunnel lags behind the heading face of the preceding tunnel by not less than 35 m.
12. The upper and lower step reserved core soil excavation method for tunnel excavation according to claim 10, applied to construction of a small clear distance double tunnel, wherein the tunnel face of the following tunnel is advanced by not less than 20m from the secondary lining of the preceding tunnel.
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| CN202110790464.7A CN113565513A (en) | 2021-07-13 | 2021-07-13 | Upper and lower step reserved core soil excavation method for tunnel excavation |
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| CN202110790464.7A CN113565513A (en) | 2021-07-13 | 2021-07-13 | Upper and lower step reserved core soil excavation method for tunnel excavation |
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