CN112177616B - Method for laying steel frame of multi-arch tunnel without middle pilot tunnel - Google Patents
Method for laying steel frame of multi-arch tunnel without middle pilot tunnel Download PDFInfo
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- CN112177616B CN112177616B CN202011272994.4A CN202011272994A CN112177616B CN 112177616 B CN112177616 B CN 112177616B CN 202011272994 A CN202011272994 A CN 202011272994A CN 112177616 B CN112177616 B CN 112177616B
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 254
- 239000010959 steel Substances 0.000 title claims abstract description 254
- 238000000034 method Methods 0.000 title claims abstract description 87
- 238000010276 construction Methods 0.000 claims abstract description 38
- 238000003466 welding Methods 0.000 claims abstract description 31
- 238000009412 basement excavation Methods 0.000 claims abstract description 25
- 239000004567 concrete Substances 0.000 claims description 22
- 239000002689 soil Substances 0.000 claims description 19
- 238000006073 displacement reaction Methods 0.000 claims description 12
- 238000005192 partition Methods 0.000 claims description 12
- 230000008093 supporting effect Effects 0.000 claims description 10
- 239000011378 shotcrete Substances 0.000 claims description 9
- 238000013461 design Methods 0.000 claims description 8
- 238000005507 spraying Methods 0.000 claims description 6
- 230000003014 reinforcing effect Effects 0.000 claims description 5
- 238000005553 drilling Methods 0.000 claims description 4
- 238000009434 installation Methods 0.000 claims description 4
- 238000005520 cutting process Methods 0.000 claims description 3
- 238000007789 sealing Methods 0.000 claims description 3
- 229910001294 Reinforcing steel Inorganic materials 0.000 claims description 2
- 239000011435 rock Substances 0.000 description 9
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- 238000012544 monitoring process Methods 0.000 description 4
- 238000005259 measurement Methods 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000005266 casting Methods 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000003754 machining Methods 0.000 description 2
- 230000001174 ascending effect Effects 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 230000007613 environmental effect Effects 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
- E21D11/04—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
- E21D11/18—Arch members ; Network made of arch members ; Ring elements; Polygon elements; Polygon elements inside arches
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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Abstract
The invention discloses a steel frame layout method for a multi-arch tunnel without a middle pilot tunnel, wherein two holes of the multi-arch tunnel are respectively provided with an independent steel arch structure, a steel arch structure of a front hole and a rear hole are arranged in a same position, in the excavation process of the front hole, the steel frames from the arch waist to the arch foot of the rear hole close to one side of a shared side wall are pre-embedded into the shared side wall, and when the rear hole is excavated, the pre-embedded steel frames and other parts of the steel arch structure of the rear hole are fixed by the steel frames, so that a complete steel arch structure of the rear hole is formed. Through changing the traditional overlap joint mode of the steel arch centering of the continuous arch tunnel without the intermediate wall, the backward tunnel is directly fallen from the original reserved welding position with the steel arch centering at the overlapped position of the forward tunnel, the mode of laying the steel arch centering is utilized, the mode of concentrated stress generated by the overlap joint of the traditional steel arch centering is changed, the stress of the tunnel structure is more reasonable, the tunnel construction is safer, and the later-stage safe operation of the tunnel is ensured.
Description
Technical Field
The invention relates to a method for laying steel frames of a multi-arch tunnel without a middle pilot tunnel, and belongs to the technical field of tunnel excavation.
Background
In recent years, the development of highways and urban roads is increasing, and the development of tunnel engineering is also increasing. The urban and rural traffic is obstructed by hills on special mountainous and hilly terrains and at the periphery of cities, and in mountainous areas with more people and less land and active economy, the occupied space is required to be reduced, the utilization rate of underground space is improved, the number of houses for residents to remove and excavate earth and stone is reduced, and the multi-arch tunnel is suitable for transportation. The multi-arch tunnel is beneficial to the selection of the opening and the body, the length of the tunnel is shortened, and the investment is reduced. The multi-arch tunnel can meet the requirement of separating the ascending vehicle from the descending vehicle, has small wiring difficulty, meets the requirement that the bridge outside the tunnel does not need amplitude division and the tunnel needs amplitude division under the condition that the tunnel and the bridge are connected, occupies less land and plays a role in environmental protection. It has become increasingly popular for short tunnel designs below 500m because of its unique advantages.
The stability, construction process and construction scheme of the surrounding rock of the multi-arch tunnel are different from those of other tunnels, and the stress conditions of the steel arch frames are different. In the actual construction of the multi-arch tunnel, the way that the steel arch centering of the rear tunnel is lapped on the steel arch centering of the front tunnel is often adopted for supporting, which is equivalent to the way of concentrated force acting on the steel arch centering of the front tunnel, but for the tunnel structure, the uniform force is preferably acted on the structure, otherwise, the stability of the tunnel structure is extremely unfavorable, so that a corresponding solution is provided for the problem with a certain necessity.
Disclosure of Invention
The invention aims to provide a method for laying steel frames of a multi-arch tunnel without a middle pilot tunnel. Through changing the traditional overlap joint mode of the steel arch centering of the continuous arch tunnel without the intermediate wall, the backward tunnel is directly fallen from the original reserved welding position with the steel arch centering at the overlapped position of the forward tunnel, the mode of laying the steel arch centering is utilized, the mode of concentrated stress generated by the overlap joint of the traditional steel arch centering is changed, the stress of the tunnel structure is more reasonable, the tunnel construction is safer, and the later-stage safe operation of the tunnel is ensured.
The technical scheme of the invention is as follows: a steel frame layout method for a multi-arch tunnel without a middle pilot tunnel is characterized in that independent steel arch structures are arranged in two holes of the multi-arch tunnel respectively, a leading hole and a trailing hole are arranged in a same position, steel frames are embedded into a shared side wall from the arch center to the arch foot of one side, close to the shared side wall, of the trailing hole in the excavation process of the leading hole, and the embedded steel frames and other parts of the steel arch structures of the trailing hole are fixed through the steel frames when the trailing hole is excavated, so that a complete steel arch structure of the trailing hole is formed.
In the method for laying steel frames of the multi-arch tunnel without the center pilot tunnel, the steel arch frame structure comprises an upper steel frame, a middle steel frame, a lower steel frame and an inverted arch steel frame, the steel frames are machined and formed outside the tunnel according to design requirements, the steel frames are installed in the tunnel after the concrete is initially sprayed, the steel frames are connected with positioning tie bars and anchor rods during installation, and welding shrinkage allowance and cutting machining allowance are reserved according to process requirements during lofting.
The method for laying the steel frame of the multi-arch tunnel without the middle pilot tunnel specifically comprises the following steps:
A. dividing the pilot hole into an upper step, a middle step and a lower step according to a three-step annular reserved core soil method, wherein the middle step is divided into middle core soil and left and right side parts of the middle step; dividing the rear row of holes into a left upper part, a left lower part, a right upper part and a right lower part according to a CRD method;
B. firstly, carrying out advanced support on an upper step of a pilot tunnel, then excavating the upper step of the pilot tunnel, and synchronously constructing primary support around a pilot tunnel, wherein the primary support comprises primary sprayed concrete, laid steel bar meshes, erected upper steel frames and erected temporary steel frames, welding points are reserved on the upper steel frames, anchor rods are set, I-shaped steel cross braces are installed, and concrete is sprayed again to the designed thickness after radial anchor rods are drilled;
C. after lagging behind the upper step by 3-5m, constructing a small tunnel side wall grouting conduit and a horizontal anchor rod advanced support of a guide pit side wall at the left side part and the right side part of the middle step by utilizing a steel frame erected circularly, then staggering and excavating the left side part and the right side part of the middle step, synchronously constructing a middle steel frame, welding the middle steel frame with the upper steel frame, constructing a temporary support, finally excavating middle step core soil, drilling a radial anchor rod, and then spraying concrete to the designed thickness;
D. after lagging behind the middle step by 3-5m, constructing a grouting small conduit on the side wall of a tunnel of the lower step and a horizontal anchor rod of the side wall of a pilot tunnel by using a steel frame erected by the previous cycle, and then excavating the lower step; simultaneously, constructing a steel arch waist to a steel frame at an arch foot position of a backward tunnel at the back of each steel arch of the preceding tunnel, embedding the steel arch waist to a shared side wall, and welding and fixing by using positioning ribs;
E. after the excavation of the inverted arch of the tunnel with the prior tunnel is finished, pouring secondary lining of the inverted arch of the prior tunnel, filling the inverted arch, paving a waterproof layer and pouring secondary lining of an arch wall;
F. the construction of the rear tunnel is started, firstly, a front support of the left upper part is constructed, then, the left upper part is excavated, after the excavation is finished, a primary support and temporary supports of the bottom end, the top end and the right side end of the left upper part are constructed, the temporary supports comprise primary sprayed concrete, a steel bar net is laid, a support steel frame and a temporary steel frame are erected, the left bottom end of the support steel frame is welded and connected with a lower steel frame which is pre-embedded in the early stage, a welding point is reserved at the right side end of the support steel frame, a positioning anchor rod is set, an I-shaped steel cross brace is installed, and after a radial anchor rod is drilled, concrete is sprayed again to the designed thickness;
G. after lagging 3-5m from the upper left, the following steps are carried out in sequence: excavating a left lower soil body, primarily supporting and temporarily supporting the left side of an inverted arch, and welding the left side end of an inverted arch supporting steel frame with pre-embedded steel bars in the primary supporting process of the left side of the inverted arch; excavating a soil body at the upper right part, and performing primary support and temporary support; excavating soil at the lower right part and performing primary support on the right side of an inverted arch; welding the steel frame of the area with the steel frame of the adjacent excavated area in the primary support process, and sealing the steel frames into a ring to form a steel arch structure; and finally, pouring the inverted arch concrete of the backward tunnel, removing the temporary supports in sections, filling the inverted arches, paving a waterproof layer, and performing secondary lining on the arch wall of the backward tunnel, and repeating the steps until the tunnel excavation is finished.
In the method for laying the steel frame of the multi-arch tunnel without the middle pilot tunnel, in the process of excavating the step in the middle of the pilot tunnel, pilot pits on the left side and the right side are excavated in a staggered mode, and the staggered length is 5-10 m; and in the backward-moving tunnel excavating process, excavating the left pilot tunnel and the right pilot tunnel in a staggered mode, wherein the staggered length is 10-15 m.
In the method for laying steel frames of the multi-arch tunnel without the middle pilot tunnel, in the step D, the steel frame at the arch springing position is provided with a backing plate, a longitudinal joist and a locking anchor rod.
In the method for laying the steel frame of the multi-arch tunnel without the middle pilot tunnel, in the step F, after the front tunnel is tunneled for a certain distance, the construction of the rear tunnel is started, and the distance between the tunnel faces of the front tunnel and the rear tunnel is less than or equal to 50 m; and in the process of excavating the left upper part of the backward tunnel, paying attention to the backward tunnel steel frame reserved in the shared side wall, and observing the disturbance condition of the excavation process.
In the method for laying the steel frame of the multi-arch tunnel without the middle pilot tunnel, in the step G, when the increment of the vault subsidence of the upper right part is less than or equal to 2mm and the increment of the clearance displacement is less than or equal to 4mm, the partition walls of the left partition and the right partition are dismantled in a segmented mode, the partition walls are dismantled one by one, and secondary lining is carried out next to the partition walls.
In the method for laying the steel frames of the multi-arch tunnel without the middle pilot tunnel, the distance between two adjacent steel arches of each tunnel is 60 cm.
In the method for laying the steel frame of the multi-arch tunnel without the middle pilot tunnel, the steel frame is combined with the anchor rods, the reinforcing mesh and the sprayed concrete to form a combined support, the steel frame is erected after the concrete is sprayed for 2-4 cm for the first time, the concrete is sprayed after the steel frame is erected, and each steel frame is positioned by utilizing radial positioning reinforcing steel bars during construction.
In the method for laying the steel frame of the multi-arch tunnel without the middle pilot tunnel, each unit of the steel arch erected by the front tunnel and the rear tunnel is formed by welding I-steel and connecting steel plates, the units are connected by bolts, the channel steel and the steel plates are padded at the arch springing and the side wall feet, and the steel arch is connected into a whole by welding.
The invention has the beneficial effects that: compared with the prior art, the method has the following advantages:
1. the overlap joint mode of the steel arch of the continuous arch tunnel without the intermediate wall is changed, the mode of arranging the double-hole steel arch in a same position is utilized, the mode of concentrated stress generated by the overlap joint of the traditional steel arch is changed, the stress of the tunnel structure is more reasonable, the tunnel construction is safer, and the later-stage safe operation of the tunnel is ensured.
2. The steel arch frames are distributed in a same position, the front tunnel and the rear tunnel of the double-arch tunnel are respectively provided with the independent steel arch frames, and each steel arch frame of the front tunnel is not subjected to the action of concentrated force any more, so that the stress form is more favorable for the stability of the tunnel structure;
3. the steel arch centering of the superposed position of the backward tunnel and the forward tunnel falls from the original reserved welding position directly, the material is increased, but the steel arch centering distance of each tunnel can be adjusted from conventional 50cm to 60cm, so that the stress of each tunnel is more definite, the tunnel is more safe according to the design concept of uniformly distributed stress, and the steel arch centering distance is more economical after being adjusted.
4. The method considers the influence of factors such as the area of the section of the tunnel, the geological condition, the construction speed, the economic cost and the like on the construction of the tunnel, thereby providing control factors and construction key points and making detailed construction steps and processes; meanwhile, the construction quality of the tunnel is fed back and checked in real time by carrying out on-site monitoring on the settlement deformation and the stress-strain after construction, so that the requirements on the construction speed, the bearing capacity and the deformation of the tunnel are met, and the safe and reliable operation of the tunnel in the construction process is ensured.
Drawings
FIG. 1 is a cross-sectional view of the multi-arch tunnel construction of the present invention;
FIG. 2 is a plan view of the multi-arch tunnel construction of the present invention;
FIG. 3 is a schematic diagram of the construction of excavation of an upper step of a pilot tunnel according to the present invention;
FIG. 4 is a schematic diagram of the construction of the step excavation in the pilot tunnel according to the present invention;
FIG. 5 is a schematic view of excavation construction of a lower step of a pilot tunnel according to the present invention;
FIG. 6 is a schematic diagram of excavation construction of the left upper part of a backward tunnel;
FIG. 7 is a drawing showing the completion of the construction of the steel arch centering of the pilot tunnel according to the present invention;
FIG. 8 is a drawing for completing the construction of a steel arch frame of a backward tunnel according to the present invention;
FIG. 9 is a displacement cloud chart of the numerical calculation of surrounding rocks by the conventional method;
FIG. 10 is a cloud graph of the present invention illustrating the displacement of the surrounding rock by numerical calculation;
FIG. 11 is a displacement cloud chart of numerical calculation of a steel arch frame in a traditional method;
FIG. 12 is a cloud diagram of the numerical calculation displacement of the steel arch centering of the present invention.
Detailed Description
The invention is further illustrated by the following figures and examples, which are not to be construed as limiting the invention.
The embodiment of the invention comprises the following steps: a method for laying steel frames of a multi-arch tunnel without a middle pilot tunnel is disclosed, as shown in attached figures 1-12, independent steel arch structures are respectively arranged in the double-tunnel excavation process of the multi-arch tunnel, and the steel arch structures of a front tunnel and a rear tunnel are arranged on the same section. In the process of excavating the first-row tunnel, steel frames from the arch waist to the arch foot on one side of the second-row tunnel close to the two shared side walls are pre-embedded into the shared side walls, and when the second-row tunnel is excavated, the pre-embedded steel frames and the steel frames at other parts of the steel arch structure of the second-row tunnel are fixed, so that a complete steel arch structure of the second-row tunnel is formed.
The steel arch is formed by welding unit steel frames of an arch part and a side wall and comprises an upper steel frame, a middle steel frame, a lower steel frame and an inverted arch steel frame, wherein the steel frames are processed and formed outside a hole according to design requirements, the steel frames are arranged in the hole after primary concrete spraying, and the steel frames are connected with a positioning tie bar and an anchor rod during installation so as to enhance the combined supporting effect of the steel arch in order to ensure the overall stability and effectiveness of the steel arch. And reserving welding shrinkage allowance and cutting machining allowance according to the process requirements during lofting.
After the tunnel is excavated, firstly, anchor rods are drilled, then, reinforcing meshes are laid, arch-sleeved I-shaped steel frames are arranged, concrete is sprayed, waterproof and pouring secondary linings are carried out, and the whole tunnel is excavated according to the sequence.
The overall construction sequence is shown in fig. 1 and 2, wherein arabic numerals (1, 2, 3.) represent excavation sequence, greek letters (i, ii, iii.) represent lining support sequence, and the method specifically comprises the following steps:
A. dividing the pilot hole into an upper step 1 part, a middle step and a lower step 4 part according to a three-step annular reserved core soil method, wherein the middle step is divided into a middle core soil 3 part and a middle step left side part and a middle step right side part 2; the following hole is divided into a left upper 5 part, a left lower 6 part, a right upper 7 part and a right lower 8 part according to the CRD method. The front holes are excavated according to a three-step annular reserved core soil method, and the rear holes are excavated by a CRD (cross middle partition) method. The 2 methods are combined, so that the settlement and displacement in the excavation process are small, and the disturbance on the shared side wall is small.
B. Firstly, performing corresponding advanced support according to design requirements, then excavating an upper step 1 part of a pilot tunnel, synchronously constructing a primary support I part around a pilot tunnel, wherein the primary support I part comprises primary sprayed concrete, laid steel bar meshes, erected upper steel frame and erected temporary steel frame, welding points are reserved on the upper steel frame, positioning anchor rods are set, I-shaped steel cross braces are installed, and after radial anchor rods are drilled, concrete is sprayed again to the designed thickness, and meanwhile, construction monitoring measurement is performed. As shown in fig. 3.
C. After lagging behind the upper step by 3-5m, constructing a small tunnel side wall grouting conduit and a horizontal anchor rod advanced support of a guide pit side wall at the left side and the right side of the middle step by utilizing a steel frame erected in the previous cycle, then staggering 2 parts at the left side and the right side of the middle step, synchronously constructing II parts of the middle steel frame, welding the II parts with the upper steel frame, constructing a temporary support, finally excavating 3 parts of the core soil of the middle step, drilling a radial anchor rod, then spraying concrete again to the designed thickness, and simultaneously performing construction monitoring and measurement. As shown in fig. 4.
D. After lagging behind the middle step by 3-5m, a steel frame erected by the previous cycle is used for constructing a small grouting conduit on the side wall of a tunnel at the 4 parts of the lower step and a horizontal anchor rod of the side wall of a guide pit for advanced support, then the 4 parts of the lower step are excavated, after the 4 parts of the lower step are excavated, a steel frame III at the lower part, including an arch foot and an inverted arch steel frame, is constructed by welding and sealing with a middle steel frame to form a ring, and then the next cycle is started. And simultaneously, constructing steel frames from the arch waist to the arch foot of the backward hole behind each steel arch of the preceding hole, pre-embedding the steel frames into the shared side wall, welding and fixing by using positioning ribs, and exposing the end part of the backward hole after the backward hole is excavated so as to weld the backward hole with the steel arches of the backward hole and connect the backward hole and the steel arches into a whole.
E. And after the excavation of the inverted arch of the tunnel with the pilot tunnel is finished, pouring a secondary lining of the inverted arch of the pilot tunnel, filling the IV part of the inverted arch, paving a waterproof layer, and pouring a secondary lining of an arch wall on the V part, as shown in the attached drawing 5.
F. And after the first tunnel is tunneled for 50m, the second tunnel starts construction. Firstly constructing an advance support of a VI part, then excavating a left upper part 5, after the excavation is finished, constructing a primary support and temporary supports of a VII a part at the bottom end of the left upper part, a VI part at the top end and a VII b part at the right side end, wherein the temporary supports comprise primary sprayed concrete, laid steel bar meshes, erected support steel frames and temporary steel frames, the left bottom end of each support steel frame is welded with a lower steel frame pre-embedded in the early stage, a welding point is reserved at the right side end of each support steel frame, a positioning anchor rod is set, and an I-shaped steel cross brace is installed. At this time, special attention should be paid to the backward hole steel frame reserved in the shared side wall, and the disturbance to the forward hole side wall is reduced as much as possible. And after drilling the radial anchor rod, spraying concrete again to the designed thickness, and simultaneously carrying out construction monitoring measurement. As shown in fig. 6.
G. After lagging 3-5m from the upper left, the following steps are carried out in sequence: excavating 6 lower left soil bodies, and performing primary support and temporary support on the left sides of inverted arches at the VIII part and the VII c part, wherein the left side end of an inverted arch support steel frame is welded with pre-embedded steel bars in the primary support process of the left side of the inverted arch; excavating 7 soil bodies on the upper right, and performing primary support and temporary support on an IX part and a VIId part; excavating 8 soil bodies at the lower right part, and performing primary support on the right side of the inverted arch at the X part. And in the primary support process, welding the steel frame of the area with the steel frame of the adjacent excavated area, so that the steel frames are sealed to form a ring to form a steel arch structure. And finally, casting a backward cave inverted arch concrete XI part, dismantling temporary supports in sections, namely VIIa, VIIb, VIIc and VIId parts, filling an inverted arch, paving a waterproof layer, and casting a backward cave arch wall secondary lining, wherein after the whole construction process is finished, the construction process is as shown in figure 1. And repeating the steps until the tunnel excavation is finished.
In the process of excavating steps in the pilot tunnel, excavating guide pits on the left side and the right side in a staggered mode, wherein the staggered length is 5-10 m; and in the backward-moving tunnel excavation process, the left pilot tunnel and the right pilot tunnel are excavated in a staggered mode, and the staggered length is 10-15 m. And the disturbance to the surrounding rock mass in the excavation process is reduced.
In the step D, the steel frame at the arch springing position is provided with a backing plate, a longitudinal joist and a foot locking anchor rod so as to enhance the stability of the steel frame.
And G, when the increment of the vault subsidence of the upper right 7 part is less than or equal to 2mm and the increment of the clearance displacement is less than or equal to 4mm, starting to demolish the intermediate walls of the left partition and the right partition in a subsection mode, namely VIIb and VIIc parts, demolishing the intermediate walls one by one, and immediately applying secondary lining.
The steel arch centering of the superposed position of the backward tunnel and the forward tunnel falls from the original reserved welding position directly, and the material is increased to a certain extent; but the steel arch spacing of each hole can be adjusted from conventional 50cm to 60cm, so that the stress of each hole is more definite, the design concept of uniform distribution stress of the tunnel is more met, the tunnel is safer, and the steel arch spacing is more economical after adjustment.
The steel arch frame is combined with the anchor rod, the reinforcing mesh and the sprayed concrete, and the steel arch frame is welded with the exposed head of the anchor rod and the reinforcing mesh as much as possible to form a combined support, so that the effectiveness of the support is enhanced, and the stress condition is better. Each unit of the steel frame is formed by welding I-shaped steel, connecting steel plates and the like, is prefabricated on site, and is connected with each other through bolts. And erecting the I-shaped steel frame after the concrete with the length of 2-4 cm is initially sprayed, and spraying the concrete after the erection. And each steel frame is positioned by utilizing the radial positioning steel bar in construction so as to ensure the installation quality of the steel frame.
The method is improved on the basis of some theories of the traditional steel arch design of the multi-arch tunnel, and has the outstanding advantages that the stress form of the tunnel steel arch is changed, so that the stress of the tunnel steel arch is more reasonable, the tunnel steel arch can participate in resisting the deformation of surrounding rocks more effectively, and the bearing capacity of the steel arch is exerted to the maximum. The method for laying the novel steel frame of the middle wall of the multi-arch tunnel well solves the problem that the traditional steel arch frame of the multi-arch tunnel causes the cracking of the tunnel, and has the advantages of simple structure, safety, reliability, flexibility and obvious economic benefit. The method has a good reference function for the construction of the later multi-arch tunnel, in particular to the multi-arch tunnel without the intermediate wall.
The steel frame material saved by the method can be analyzed simply and quantitatively, if each steel arch (including the steel arch of the leading hole and the trailing hole with the same section) in the traditional method is 80m, the steel frame spacing is 0.5 m; considering that the steel arch frame of the backward tunnel of the invention falls from the original lap joint point directly, the material is increased, and the increased steel frame is assumed to be 6m (the actual construction should be considered specifically), each steel arch frame (including the steel arch frame of the forward tunnel and the backward tunnel with the same section) of the invention is 86m, and the steel frame layout space is 0.6 m. 22b I-steel is adopted in both methods, the mass of each meter of steel frame is 36.5kg, and steel frame materials can be saved in each kilometer of tunnel:
1000÷0.5×80×36.5-1000÷0.6×86×36.5＝608333kg＝608.333t
the steel frame layout method can save about six hundred tons of steel frames per kilometer of the tunnel, and has remarkable economic benefit.
Numerical simulation
Now, numerical analysis is performed on the conventional method for laying the steel arch of the multi-arch tunnel and the new method through finite element numerical simulation software, and the deformation calculation results of the surrounding rock and the steel arch of the two laying methods are shown in fig. 9-12:
as can be seen from fig. 9 and 10, the maximum displacement values of the surrounding rock of the conventional layout method and the new method are respectively: 1.27X 10-2m and 3.20X 10-3And m, the calculation result shows that the maximum value of the deformation displacement of the surrounding rock of the new method is 74.8 percent smaller than that of the traditional arrangement method. This shows that the new method can control the deformation of the surrounding rock more effectively with the change of the layout method.
As can be seen from fig. 11 and 12, the maximum displacement values of the steel arch of the conventional layout method and the new method are: 1.27X 10-2m and 3.20X 10-3m, the calculation result shows thatThe maximum value of the deformation displacement of the steel arch frame is 74.8 percent smaller than that of the steel arch frame in the traditional layout method.
Claims (8)
1. A method for laying steel frames of a multi-arch tunnel without a middle pilot tunnel is characterized by comprising the following steps: the double holes of the multi-arch tunnel are respectively provided with independent steel arch structures, the steel arch structures of the front hole and the rear hole are arranged in a same position, the steel frames from the arch waist to the arch foot of one side, close to the shared side wall, of the rear hole are embedded into the shared side wall in the excavation process of the front hole, and when the rear hole is excavated, the embedded steel frames and other parts of the steel arch structures of the rear hole are fixed through the steel frames, so that a complete steel arch structure of the rear hole is formed;
the steel arch frame structure comprises an upper steel frame, a middle steel frame, a lower steel frame and an inverted arch steel frame, wherein the steel frames are processed and molded outside a hole according to design requirements, the steel frames are arranged in the hole after the concrete is sprayed, the steel frames are connected with positioning tie bars and anchor rods during installation, and welding shrinkage allowance and cutting allowance are reserved according to process requirements during lofting;
the method specifically comprises the following steps:
A. dividing the pilot hole into an upper step, a middle step and a lower step according to a three-step annular reserved core soil method, wherein the middle step is divided into middle core soil and left and right side parts of the middle step; dividing the rear row of holes into a left upper part, a left lower part, a right upper part and a right lower part according to a CRD method;
B. firstly, carrying out advanced support on an upper step of a pilot tunnel, then excavating the upper step of the pilot tunnel, and synchronously constructing primary support around a pilot tunnel, wherein the primary support comprises primary sprayed concrete, laid steel bar meshes, erected upper steel frames and erected temporary steel frames, welding points are reserved on the upper steel frames, anchor rods are set, I-shaped steel cross braces are installed, and concrete is sprayed again to the designed thickness after radial anchor rods are drilled;
C. after lagging behind the upper step by 3-5m, constructing a small tunnel side wall grouting conduit and a horizontal anchor rod advanced support of a guide pit side wall at the left side part and the right side part of the middle step by utilizing a steel frame erected circularly, then staggering and excavating the left side part and the right side part of the middle step, synchronously constructing a middle steel frame, welding the middle steel frame with the upper steel frame, constructing a temporary support, finally excavating middle step core soil, drilling a radial anchor rod, and then spraying concrete to the designed thickness;
D. after lagging behind the middle step by 3-5m, constructing a grouting small conduit on the side wall of a tunnel of the lower step and a horizontal anchor rod of the side wall of a pilot tunnel by using a steel frame erected by the previous cycle, and then excavating the lower step; simultaneously, constructing a steel arch waist to a steel frame at an arch foot position of a backward tunnel at the back of each steel arch of the preceding tunnel, embedding the steel arch waist to a shared side wall, and welding and fixing by using positioning ribs;
E. after the excavation of the inverted arch of the tunnel with the prior tunnel is finished, pouring secondary lining of the inverted arch of the prior tunnel, filling the inverted arch, paving a waterproof layer and pouring secondary lining of an arch wall;
F. the construction of the rear tunnel is started, firstly, a front support of the left upper part is constructed, then, the left upper part is excavated, after the excavation is finished, a primary support and temporary supports of the bottom end, the top end and the right side end of the left upper part are constructed, the temporary supports comprise primary sprayed concrete, a steel bar net is laid, a support steel frame and a temporary steel frame are erected, the left bottom end of the support steel frame is welded and connected with a lower steel frame which is pre-embedded in the early stage, a welding point is reserved at the right side end of the support steel frame, a positioning anchor rod is set, an I-shaped steel cross brace is installed, and after a radial anchor rod is drilled, concrete is sprayed again to the designed thickness;
G. after lagging 3-5m from the upper left, the following steps are carried out in sequence: excavating a left lower soil body, primarily supporting and temporarily supporting the left side of an inverted arch, and welding the left side end of an inverted arch supporting steel frame with pre-embedded steel bars in the primary supporting process of the left side of the inverted arch; excavating a soil body at the upper right part, and performing primary support and temporary support; excavating soil at the lower right part and performing primary support on the right side of an inverted arch; welding the steel frame of the area with the steel frame of the adjacent excavated area in the primary support process, and sealing the steel frames into a ring to form a steel arch structure; and finally, pouring the inverted arch concrete of the backward tunnel, removing the temporary supports in sections, filling the inverted arches, paving a waterproof layer, and performing secondary lining on the arch wall of the backward tunnel, and repeating the steps until the tunnel excavation is finished.
2. The layout method of the steel frame of the multi-arch tunnel without the central pilot tunnel according to claim 1, which is characterized in that: in the process of excavating steps in the pilot tunnel, excavating guide pits on the left side and the right side in a staggered mode, wherein the staggered length is 5-10 m; and in the backward-moving tunnel excavation process, the left pilot tunnel and the right pilot tunnel are excavated in a staggered mode, and the staggered length is 10-15 m.
3. The layout method of the steel frame of the multi-arch tunnel without the central pilot tunnel according to claim 1, which is characterized in that: in the step D, the steel frame at the arch springing position is provided with a backing plate, a longitudinal joist and a locking anchor rod.
4. The layout method of the steel frame of the multi-arch tunnel without the central pilot tunnel according to claim 1, which is characterized in that: step F, after the first tunnel is tunneled for a certain distance, the construction of the backward tunnel is started, and the distance between the tunnel faces of the first tunnel and the backward tunnel is less than or equal to 50 m; and in the process of excavating the left upper part of the backward tunnel, paying attention to the backward tunnel steel frame reserved in the shared side wall, and observing the disturbance condition of the excavation process.
5. The layout method of the steel frame of the multi-arch tunnel without the central pilot tunnel according to claim 1, which is characterized in that: and G, when the increment of the vault subsidence of the upper right part is less than or equal to 2mm and the increment of the clearance displacement is less than or equal to 4mm, the partition walls of the left partition and the right partition are removed in a segmented mode, the partition walls are removed one by one, and secondary lining is performed immediately.
6. The layout method of the steel frame of the multi-arch tunnel without the central pilot tunnel according to claim 1, which is characterized in that: the distance between two adjacent steel arches in each hole is 60 cm.
7. The layout method of the steel frame of the multi-arch tunnel without the central pilot tunnel according to claim 1, which is characterized in that: the steel frames are combined with anchor rods, a reinforcing mesh and sprayed concrete to form combined support, the steel frames are erected after 2-4 cm of concrete is sprayed for the first time, the concrete is sprayed after the erection, and each steel frame is positioned by utilizing radial positioning reinforcing steel bars in construction.
8. The layout method of the steel frame of the multi-arch tunnel without the central pilot tunnel according to claim 1, which is characterized in that: the steel arch centering erected in the front tunnel and the rear tunnel is formed by welding I-steel and connecting steel plates, the units are connected by bolts, channel steel and steel plates are padded at the arch springing and the side wall feet, and the steel arch centering is connected into a whole by welding.
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| DE3508987A1 (en) * | 1985-03-13 | 1986-09-18 | HLS-Verwaltung GmbH, 4630 Bochum | Bendable profile connection |
| DE3626948A1 (en) * | 1986-08-08 | 1988-02-18 | Bergwerksverband Gmbh | Apparatus for placing an arch support |
| CN102279017B (en) * | 2011-04-29 | 2012-08-29 | 重庆大学 | Method and system for monitoring stability of midboard of highway multi-arch tunnel and construction method |
| KR101143236B1 (en) * | 2011-07-29 | 2012-05-18 | 주식회사 스판코리아 | Device of slab forms one piece type sound absorption tunnel used double type arch panel |
| CN102305077A (en) * | 2011-09-23 | 2012-01-04 | 中南大学 | Rapid construction method of large-section multi-arc tunnel |
| CN104533431A (en) * | 2015-01-08 | 2015-04-22 | 云南省交通规划设计研究院 | Construction method for multiple-arch tunnel without middle walls |
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| CN110043268B (en) * | 2019-04-16 | 2020-09-01 | 贵州大学 | Penetrating method for intersection of underground excavated subway station and inter-section tunnel in shape of Chinese character' pin |
| CN110630283B (en) * | 2019-09-12 | 2020-11-24 | 山东大学 | Three-layer supporting structure suitable for double-arch tunnel and construction method |
| CN110924952B (en) * | 2019-12-06 | 2021-05-14 | 中铁二院贵阳勘察设计研究院有限责任公司 | Construction method for three-step seven-step normal medium rock pillar method conversion of super-large section tunnel |
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