CN111561322A - Construction structure and construction method of water-rich weak surrounding rock large-section tunnel - Google Patents
Construction structure and construction method of water-rich weak surrounding rock large-section tunnel Download PDFInfo
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- CN111561322A CN111561322A CN202010413578.5A CN202010413578A CN111561322A CN 111561322 A CN111561322 A CN 111561322A CN 202010413578 A CN202010413578 A CN 202010413578A CN 111561322 A CN111561322 A CN 111561322A
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- 238000010276 construction Methods 0.000 title claims abstract description 71
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 47
- 239000011435 rock Substances 0.000 title claims abstract description 28
- 238000009412 basement excavation Methods 0.000 claims abstract description 9
- 239000004576 sand Substances 0.000 claims description 6
- 239000010438 granite Substances 0.000 claims description 5
- 238000000034 method Methods 0.000 abstract description 16
- 238000005516 engineering process Methods 0.000 abstract description 3
- 229910000831 Steel Inorganic materials 0.000 description 8
- 239000010959 steel Substances 0.000 description 8
- 230000003014 reinforcing effect Effects 0.000 description 7
- 238000005553 drilling Methods 0.000 description 4
- 230000002787 reinforcement Effects 0.000 description 4
- 239000011378 shotcrete Substances 0.000 description 4
- 239000002002 slurry Substances 0.000 description 4
- 239000004568 cement Substances 0.000 description 2
- 239000004567 concrete Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000004570 mortar (masonry) Substances 0.000 description 2
- 239000004575 stone Substances 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- 230000004075 alteration Effects 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
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- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 230000006837 decompression Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
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- 239000007788 liquid Substances 0.000 description 1
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- 238000005086 pumping Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000011150 reinforced concrete Substances 0.000 description 1
- 238000009991 scouring Methods 0.000 description 1
- 239000002689 soil Substances 0.000 description 1
- 230000001052 transient 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
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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
- E21D11/105—Transport or application of concrete specially adapted for the lining of tunnels or galleries ; Backfilling the space between main building element and the surrounding rock, e.g. with concrete
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21F—SAFETY DEVICES, TRANSPORT, FILLING-UP, RESCUE, VENTILATION, OR DRAINING IN OR OF MINES OR TUNNELS
- E21F16/00—Drainage
- E21F16/02—Drainage of tunnels
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Abstract
The invention discloses a construction structure of a water-rich weak surrounding rock large-section tunnel, which comprises a stepped upper structure, a stepped middle structure and a stepped lower structure, wherein the upper structure comprises an upper first side wall pit guide upper step, an upper first side wall pit guide lower step, an upper middle groove, an upper second side wall pit guide upper step and an upper second side wall pit guide lower step; the middle structure includes a middle first side and a middle second side, and the lower structure includes a lower first side and a lower second side. The invention also correspondingly provides a construction method. Compared with the traditional construction technologies such as double-side-wall pilot pits and the like, the method optimizes excavation and supporting methods, has a high supporting system safety coefficient, can solve a plurality of engineering geological problems such as rapid deformation, collapse, water inrush and the like in tunnel construction, and ensures construction safety.
Description
Technical Field
The invention belongs to the field of tunnels, and particularly relates to a construction structure and a construction method of a tunnel.
Background
When a large-section tunnel passes through large-section weak surrounding rock strata such as a water-rich completely weathered granite altered zone, a third series non-diagenetic water-bearing sand layer, a water-rich fault and the like, a plurality of engineering geological problems such as rapid deformation, collapse, water inrush and the like are easily caused, and great difficulty is brought to construction.
The double-side-wall pilot tunnel method is that two middle partition walls are utilized to divide the whole large section of the tunnel into a left small section, a middle small section and a right small section for construction, a left pilot tunnel and a right pilot tunnel move first, and the middle section is followed by the middle section; after the primary support inverted arch is looped, the temporary supports of the pilot tunnels on the two sides are removed to form a full section. The method is suitable for construction environments of cohesive soil layers, sand layers and the like. However, when the existing double-side-wall pit guiding method is used for constructing the large-section weak surrounding rock stratum, the construction safety risk is still very high, and various engineering geological problems such as rapid deformation, collapse, water inrush and the like are easy to occur in the construction process.
Disclosure of Invention
The technical problem to be solved by the invention is to overcome the defects and shortcomings in the background technology, and provide a construction structure and a construction method of a water-rich weak surrounding rock large-section tunnel with good construction safety. In order to solve the technical problems, the technical scheme provided by the invention is as follows:
the construction structure of the water-rich weak surrounding rock large-section tunnel comprises a stepped upper structure, a stepped middle structure and a stepped lower structure, wherein the upper structure comprises an upper first side wall pit guide upper step, an upper first side wall pit guide lower step, an upper middle groove, an upper second side wall pit guide upper step and an upper second side wall pit guide lower step; the middle structure includes a middle first side and a middle second side, and the lower structure includes a lower first side and a lower second side.
In the above construction structure, preferably, the upper step of the upper first sidewall pit guide is ahead of the upper step of the upper second sidewall pit guide, and a distance between the upper step of the upper first sidewall pit guide and the tunnel face of the upper step of the upper second sidewall pit guide is 5-12 m; the upper first side wall pit guiding lower step is ahead of the upper second side wall pit guiding lower step, and the distance between the upper first side wall pit guiding lower step and the tunnel face of the upper second side wall pit guiding lower step is 5-12 m; the upper first side wall pit guiding upper step is ahead of the upper first side wall pit guiding lower step, and the distance between the upper first side wall pit guiding upper step and the tunnel face of the upper first side wall pit guiding lower step is 3-8 m; the upper second side wall pit guiding upper step is ahead of the upper second side wall pit guiding lower step, and the distance between the upper second side wall pit guiding upper step and the lower step face of the upper second side wall pit guiding lower step is 3-8 m.
In the above construction structure, preferably, the lower step of the upper second sidewall pit guide leads the upper middle groove, and a distance between the lower step of the upper second sidewall pit guide and a tunnel face of the upper middle groove is 5 to 12 m.
In the above construction structure, preferably, the upper middle groove leads the first side of the middle part, and a distance between the upper middle groove and a tunnel face of the first side of the middle part is 5 to 12 m; the first side of the middle part leads the second side of the middle part, and the distance between the first side of the middle part and the second side of the middle part is 1-5 m.
In the above construction structure, preferably, the middle second side is ahead of the lower first side, and a distance between the middle second side and the lower first side is 2 to 8 m; the first side of the lower part is ahead of the second side of the lower part, and the distance between the first side of the lower part and the second side of the lower part is 1-5 m.
As a general technical concept, the present invention also provides a construction method for the construction structure of the water-rich weak surrounding rock large-section tunnel, comprising the steps of:
s1: constructing an advance support;
s2: excavating an upper step of a first side wall pilot tunnel at the upper part, and constructing a first side wall temporary support and a primary support on an excavated surface;
s3: excavating a lower step of a first side wall pilot tunnel at the upper part, and constructing a second side wall temporary support and a primary support on an excavated surface;
s4: excavating an upper step of a second side wall pilot tunnel at the upper part, and applying a third side wall temporary support and a primary support to an excavated surface;
s5: excavating a lower step of a second side wall pilot tunnel at the upper part, and constructing a fourth side wall temporary support and a primary support on an excavated surface;
s6: dismantling the first side wall temporary support, the second side wall temporary support, the third side wall temporary support and the fourth side wall temporary support, excavating an upper middle groove, and constructing a primary support for an excavated surface;
s7: excavating a first side in the middle, and applying primary support to an excavated surface;
s8: excavating a second side in the middle, and applying primary support to an excavated surface;
s9: excavating a first side of the lower part, and applying primary support and an inverted arch to an excavated surface; the construction of the inverted arch is realized by excavating the earth and stone of the inverted arch;
s10: excavating a second side of the lower part, and applying primary support and an inverted arch to the excavated surface; the construction of the inverted arch is realized by excavating the earth and stone of the inverted arch;
s11: and constructing an inverted arch, filling, constructing a secondary lining, and pouring inverted arch reinforced concrete at the position of constructing the inverted arch.
In the above construction method, preferably, before excavating the upper step of the upper first sidewall pit guide, the lower step of the upper first sidewall pit guide, the upper step of the upper second sidewall pit guide and the lower step of the upper second sidewall pit guide, a row of guide pipes (for example, phi 42 small guide pipes) are firstly constructed on the outer edges of the upper step of the first sidewall pit guide, the lower step of the upper first sidewall pit guide, the upper step of the upper second sidewall pit guide and the lower step of the upper second sidewall pit guide, and then the surrounding rock is excavated after grouting and reinforcing.
In the above construction method, preferably, after the upper step of the upper first sidewall pit guide, the lower step of the upper first sidewall pit guide, the upper step of the upper second sidewall pit guide and the lower step of the upper second sidewall pit guide are excavated, temporary inverted arches are applied to the bottom of the upper step of the first sidewall pit guide, the bottom of the lower step of the upper first sidewall pit guide, the bottom of the upper step of the upper second sidewall pit guide and the bottom of the lower step of the upper second sidewall pit guide.
In the above construction method, preferably, the upper step of the upper first sidewall pilot tunnel, the lower step of the upper first sidewall pilot tunnel, the upper step of the upper second sidewall pilot tunnel, the lower step of the upper second sidewall pilot tunnel and the upper middle groove are constructed simultaneously in left, middle and right directions; the first side of the middle part and the second side of the middle part adopt the construction of the left side and the right side simultaneously; the first side of the lower part and the second side of the lower part adopt the construction of the left side and the right side simultaneously. The construction mode can ensure the construction efficiency. The invention can also adopt the line production to each part, namely the sequential construction.
In the construction method, preferably, a foot-locking anchor rod (phi 22 positioning mortar anchor rod) is arranged when a first side wall temporary support, a second side wall temporary support, a third side wall temporary support and a fourth side wall temporary support are constructed; the primary support is provided with a foot locking anchor rod.
In the above construction method, preferably, the cross-sectional area of the large-section tunnel of the water-rich weak surrounding rock is 120-180m2The water-rich weak surrounding rock refers to a water-rich completely weathered granite altered zone, a third series of non-diagenetic sand layer and a water-rich fault.
According to the construction method, the construction cycle time of the invention is 30-35 days, namely 45m/30-35 days
Compared with the prior art, the invention has the advantages that:
due to the fact that the stability of surrounding rocks of large-section unfavorable geological tunnels such as a water-rich completely weathered granite altered zone, a third series of unconsolidated rock water-bearing sand layer, a water-rich fault and the like is extremely poor, the construction structure and the construction method are divided into nine parts for excavation and supporting; and then, by utilizing the concept of 'large tunnel and small driving', construction is started from the periphery of the arch part of the circular tunnel according to a certain sequence, construction is carried out on the upper part of the tunnel by adopting a micro-step double-side-wall pit guide belt middle groove with left and right staggered and a micro-step method with left and right staggered middle and lower parts, support is excavated in nine small parts, the stress of the surrounding rock is converted to the primary support through the conversion of a stress system for many times, and the surrounding rock and the support form a stable stress system. Compared with the traditional construction technologies such as double-side-wall pilot pits and the like, the method optimizes excavation and supporting methods, has a high supporting system safety coefficient, can solve a plurality of engineering geological problems such as rapid deformation, collapse, water inrush and the like in tunnel construction, and ensures construction safety.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a schematic elevation view of the construction structure of the present invention.
Fig. 2 is a side view schematically showing the construction structure of the present invention.
Illustration of the drawings:
1. advance support; 2. an upper step of the upper first side wall pit; 3. a first side wall pit guiding lower step at the upper part; 4. an upper second sidewall pit guide upper step; 5. a second side wall pit guiding lower step at the upper part; 6. an upper middle groove; 7. a middle first side; 8. a second side of the middle portion; 9. a lower first side; 10. a lower second side; 11. primary support; 12. a conduit; 13. a temporary inverted arch; 14. locking the anchor rod; 100. temporarily supporting a first side wall; 200. temporarily supporting the second side wall; 300. a third side wall temporary support; 400. and (5) temporarily supporting the fourth side wall.
Detailed Description
In order to facilitate an understanding of the invention, the invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of the invention is not limited to the specific embodiments below.
Unless otherwise defined, all terms of art used hereinafter have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present invention.
Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment and the like used in the present invention are commercially available or can be prepared by existing methods.
Example (b):
as shown in fig. 1 and fig. 2, the construction structure of the water-rich weak surrounding rock large-section tunnel of the present embodiment includes a stepped upper structure, a stepped middle structure and a stepped lower structure, where the upper structure includes an upper first sidewall pit upper step 2, an upper first sidewall pit lower step 3, an upper middle groove 6, an upper second sidewall pit upper step 4 and an upper second sidewall pit lower step 5, the upper first sidewall pit upper step 2 and the upper first sidewall pit lower step 3 are stepped, and the upper second sidewall pit upper step 4 and the upper second sidewall pit lower step 5 are stepped; the middle structure comprises a middle first side 7 and a middle second side 8 and the lower structure comprises a lower first side 9 and a lower second side 10.
As shown in fig. 2, in the present embodiment, the upper first sidewall pit upper step 2 is ahead of the upper second sidewall pit upper step 4, and the distance between the upper first sidewall pit upper step 2 and the tunnel face of the upper second sidewall pit upper step 4 is 8 m; the upper first side wall pit guiding lower step 3 is ahead of the upper second side wall pit guiding lower step 5, and the distance between the upper first side wall pit guiding lower step 3 and the tunnel face of the upper second side wall pit guiding lower step 5 is 8 m; the upper first side wall pit guiding upper step 2 is ahead of the upper first side wall pit guiding lower step 3, and the distance between the upper first side wall pit guiding upper step 2 and the tunnel face of the upper first side wall pit guiding lower step 3 is 5 m; the upper second side wall pit guiding upper step 4 is ahead of the upper second side wall pit guiding lower step 5, and the distance between the upper second side wall pit guiding upper step 4 and the tunnel face of the upper second side wall pit guiding lower step 5 is 5 m; the upper second side wall pit guiding lower step 5 is ahead of the upper middle groove 6, and the distance between the upper second side wall pit guiding lower step 5 and the face of the upper middle groove 6 is 8 m. The upper middle groove 6 leads the middle first side 7, and the distance between the upper middle groove 6 and the middle first side 7 is 8 m; the middle part first side 7 is ahead of the middle part second side 8, and the distance between the middle part first side 7 and the middle part second side 8 is 3 m; the middle second side 8 is ahead of the lower first side 9, and the distance between the middle second side 8 and the tunnel face of the lower first side 9 is 5 m; the lower first side 9 is ahead of the lower second side 10, and the distance between the lower first side 9 and the lower second side 10 is 3 m. The length of the lower second side 10 is 5 m. The length of the whole construction cycle is 45 m.
The embodiment also provides a construction method of the water-rich weak surrounding rock large-section tunnel, which comprises the following steps:
s1: constructing an advance support 1;
s2: excavating an upper step 2 of a first side wall pilot tunnel at the upper part, and constructing a first side wall temporary support 100 and a primary support 11 on an excavated surface;
s3: excavating a first side wall pilot tunnel lower step 3 on the upper part, and constructing a second side wall temporary support 200 and a primary support 11 on an excavation surface;
s4: excavating an upper step 4 of the upper second side wall pilot tunnel, and constructing a third side wall temporary support 300 and a primary support 11 on an excavated surface;
s5: excavating a lower step 5 of the upper second side wall pilot tunnel, and constructing a fourth side wall temporary support 400 and a primary support 11 on an excavated surface;
s6: dismantling the first side wall temporary support 100, the second side wall temporary support 200, the third side wall temporary support 300 and the fourth side wall temporary support 400, excavating an upper middle groove 6, and constructing a primary support 11 on an excavated surface;
s7: excavating a first side 7 in the middle, and applying a primary support 11 to an excavated surface;
s8: excavating a second side 8 in the middle, and applying a primary support 11 to an excavated surface;
s9: excavating a first side 9 of the lower part, and applying a primary support 11 and an inverted arch to an excavated surface;
s10: excavating a second side 10 of the lower part, and applying a primary support 11 and an inverted arch to an excavated surface;
s11: constructing an inverted arch, filling and constructing a secondary lining.
In this embodiment, before excavating the upper first sidewall pit guiding upper step 2, the upper first sidewall pit guiding lower step 3, the upper second sidewall pit guiding upper step 4, and the upper second sidewall pit guiding lower step 5, a row of guide pipes 12 (phi 42 small guide pipes, with a spacing of 0.5m) are firstly constructed at the outer edges of the upper first sidewall pit guiding upper step, the upper first sidewall pit guiding lower step 3, the upper second sidewall pit guiding upper step 4, and the upper second sidewall pit guiding lower step 5, and then the surrounding rock is excavated after grouting and reinforcing.
In this embodiment, after the upper first sidewall pit guiding upper step 2, the upper first sidewall pit guiding lower step 3, the upper second sidewall pit guiding upper step 4, and the upper second sidewall pit guiding lower step 5 are excavated, the temporary inverted arch 13 is applied to the bottom of the first sidewall pit guiding upper step, the bottom of the upper first sidewall pit guiding lower step 3, the bottom of the upper second sidewall pit guiding upper step 4, and the bottom of the upper second sidewall pit guiding lower step 5. And after the supporting structure is stable, removing the temporary inverted arch 13, and excavating the upper middle groove 6.
In the embodiment, an upper first side wall pit guiding upper step 2, an upper first side wall pit guiding lower step 3, an upper second side wall pit guiding upper step 4, an upper second side wall pit guiding lower step 5 and an upper middle groove 6 are constructed in a left-middle-right mode; the first side 7 and the second side 8 of the middle part are constructed at the left side and the right side simultaneously; the lower first side 9 and the lower second side 10 are constructed simultaneously by adopting the left side and the right side. In this embodiment, the components may be subjected to line production, i.e., sequential construction.
In this embodiment, when the first, second, third, and fourth side wall temporary supports 100, 200, 300, and 400 are constructed, the foot-locking anchor rods 14 (one each of the mortar anchor rods with a diameter of 22 mm, and a single bolt is 4.5m long) are provided; the preliminary support 11 is provided with a locking bolt 14. During construction, the grouting of the foot-locking anchor rods 14 is emphasized, the rigidity of the foot-locking support is enhanced, and the deformation effect of the primary support in the pitching process is very obvious.
In this embodiment, the cross-sectional area of the large-section tunnel of the water-rich weak surrounding rock is 120-2The water-rich weak surrounding rock refers to a water-rich completely weathered granite altered zone, a third series of non-diagenetic rock water-containing sand layer and a water-rich fault.
In this embodiment, after the pilot tunnel on one side is constructed, the side can be used as a drainage channel to guide water flow to the pilot tunnel for drainage, so as to reduce the construction water flow of the pilot tunnel on the other side and reduce the construction difficulty.
In this embodiment, the first, second, third and fourth side wall temporary supports 100, 200, 300 and 400 are made of I18 steel frames, with a mesh reinforcement of Φ 8@25 × 25cm, and a C25 concrete sprayed thereon to a thickness of 20 cm. The excavation is carried out by adopting a manual matching machine, the construction length is 1 steel frame space (0.5-0.6m) each time, and temporary support is immediately carried out on the side wall after the excavation. The primary support 11 adopts I25b steel frames, the distance between the steel frames is 0.6m, C25 sprayed concrete, the thickness is 30cm, phi 8 reinforcing mesh is adopted, and the mesh distance is 20cm multiplied by 20 cm. The temporary inverted arch 13 is closed into a ring by using I18 steel to support sprayed concrete, and the thickness of the sprayed concrete is 20 cm.
In this embodiment, before the advance support 1 is constructed, the processes of advance geological prediction, pipe burying drainage, water drainage and pressure reduction, tunnel face grouting pre-reinforcement, cavity backfilling and the like can be performed. Advanced geological prediction: the method comprehensively uses physical exploration methods such as TSP, infrared water exploration, transient electromagnetism and the like, drilling methods such as advanced horizontal drilling, blast hole deepening and the like, geological analysis, sketch and other measures to comprehensively judge the stability condition of the excavation working face, pre-controls in advance and sets out targeted reinforcement measures. 5 holes 50m are drilled in advance horizontally to clarify the front geological condition, and the drilled holes are distributed at the upper, lower, left and right parts of the tunnel. In order to further ensure the accuracy of drilling, deepened blast holes are added, and the number of the holes is not less than 5. Pipe burying drainage and water drainage decompression: after the areas and the positions of the water-rich and altered zones are accurately judged, in order to ensure the grouting quality of the drill holes and the safety of primary support construction, phi 108 steel floral tubes, PVC tubes and the like are buried in the drill holes at the arch parts of the water-rich and altered zones to intensively drain the confined water to the rear of the tunnel face, and according to the water burst condition, the water discharge amount of the drill holes is required to be not less than 30m3H is used as the reference value. Grouting a tunnel face for pre-reinforcing and backfilling the cavity: grouting and reinforcing the surrounding rock after draining and reducing pressure, wherein the reinforcing range is 5m outside the excavation contour line, the slurry diffusion radius is 2.0m, and the final hole spacing is 3 m; the grouting material is mainly sulphoaluminate cement single-liquid slurry. The weathered rock of the erosion zone can form a cavity along with the water flow scouring, and the cavity needs to be cleanedProcessing; for small cavities locally appearing on the tunnel face, a framework is erected by adopting small guide pipes or waste steel bars and is connected with a peripheral rock stratum to form a whole, and then the cavities are sprayed and compacted by C25 sprayed concrete; the large cavity treatment adopts a small guide pipe or waste steel bars to set up a framework, and the cavity is filled with concrete by pumping. Through the technical process, a forward geological forecasting means combining geophysical prospecting and drilling is adopted, the water-rich and unfavorable geological distribution conditions of the front alteration zone can be accurately judged, measures such as targeted water drainage and pressure reduction, grouting pre-reinforcement, large pipe shed combined small pipe advanced support and the like are adopted, and the construction safety is high.
In this embodiment, the steps of constructing the advance support 1 are as follows: after the reinforcing and grouting are finished, in order to improve the compression resistance of the broken stratum, a phi 108 large pipe shed is constructed in a 120-degree range relative to the arch part of the water-rich section, a small guide pipe is arranged in the middle of the pipe shed for advanced support, and the advanced large pipe shed is constructed in a working-room-free mode. Because a pipe shed working chamber is not arranged, in order to meet the construction requirements, the center of the opening of the pipe shed is 20cm in the primary support contour line, the circumferential distance is 40cm, the external insertion angle is 6-8 degrees, and phi 42 small pipes are inserted between the pipe sheds according to the geological condition. And performing full-hole one-time grouting after the pipe shed and the small guide pipe are installed. The grouting material adopts sulphoaluminate cement single slurry, and the slurry proportion is W: c is 1: 1-1.2: 1, the final pressure of grouting is 3-4 MPa.
Claims (10)
1. The construction structure of the water-rich weak surrounding rock large-section tunnel is characterized by comprising a stepped upper structure, a stepped middle structure and a stepped lower structure, wherein the upper structure comprises an upper first side wall pit guiding upper step (2), an upper first side wall pit guiding lower step (3), an upper middle groove (6), an upper second side wall pit guiding upper step (4) and an upper second side wall pit guiding lower step (5), the upper first side wall pit guiding upper step (2) and the upper first side wall pit guiding lower step (3) are stepped, and the upper second side wall pit guiding upper step (4) and the upper second side wall pit guiding lower step (5) are stepped; the middle structure comprises a middle first side (7) and a middle second side (8), and the lower structure comprises a lower first side (9) and a lower second side (10).
2. Construction structure according to claim 1, wherein said upper first sidewall pit upper step (2) leads the upper second sidewall pit upper step (4), the distance between the upper first sidewall pit upper step (2) and the tunnel face of the upper second sidewall pit upper step (4) being 5-12 m;
the upper first side wall pit guiding lower step (3) is ahead of the upper second side wall pit guiding lower step (5), and the distance between the upper first side wall pit guiding lower step (3) and the tunnel face of the upper second side wall pit guiding lower step (5) is 5-12 m;
the upper first side wall pit guiding upper step (2) is ahead of the upper first side wall pit guiding lower step (3), and the distance between the upper first side wall pit guiding upper step (2) and the tunnel face of the upper first side wall pit guiding lower step (3) is 3-8 m;
the upper second side wall pit guiding upper step (4) is ahead of the upper second side wall pit guiding lower step (5), and the distance between the upper second side wall pit guiding upper step (4) and the tunnel face of the upper second side wall pit guiding lower step (5) is 3-8 m.
3. Construction structure according to claim 1, characterized in that the upper second side wall pit lower step (5) leads the upper middle trough (6), the distance between the upper second side wall pit lower step (5) and the tunnel face of the upper middle trough (6) being 5-12 m.
4. Construction structure according to any of claims 1-3, characterized in that the upper central channel (6) leads the middle first side (7), the distance between the upper central channel (6) and the tunnel face of the middle first side (7) being 5-12 m;
the middle part first side (7) leads the middle part second side (8), and the distance between the middle part first side (7) and the middle part second side (8) is 1-5 m.
5. Construction structure according to any of claims 1-3, characterized in that the middle second side (8) leads the lower first side (9), the distance between the middle second side (8) and the tunnel face of the lower first side (9) being 2-8 m;
the lower first side (9) is ahead of the lower second side (10), and the distance between the lower first side (9) and the tunnel face of the lower second side (10) is 1-5 m.
6. A construction method for a construction structure of a water-rich weak surrounding rock large-section tunnel according to any one of claims 1 to 5, characterized by comprising the steps of:
s1: constructing a forepoling (1);
s2: excavating an upper step (2) of a first side wall pilot tunnel at the upper part, and constructing a first side wall temporary support (100) and a primary support (11) on an excavated surface;
s3: excavating a first side wall pilot tunnel lower step (3) on the upper part, and constructing a second side wall temporary support (200) and a primary support (11) on an excavated surface;
s4: excavating an upper step (4) of a second side wall pilot tunnel at the upper part, and constructing a third side wall temporary support (300) and a primary support (11) on an excavated surface;
s5: excavating a second side wall pilot tunnel lower step (5) on the upper part, and constructing a fourth side wall temporary support (400) and a primary support (11) on the excavated surface;
s6: dismantling the first side wall temporary support (100), the second side wall temporary support (200), the third side wall temporary support (300) and the fourth side wall temporary support (400), excavating an upper middle groove (6), and constructing a primary support (11) on an excavated surface;
s7: excavating a first side (7) in the middle, and applying primary support (11) to an excavated surface;
s8: excavating a second side (8) in the middle, and applying primary support (11) to an excavated surface;
s9: excavating a first side (9) of the lower part, and applying a primary support (11) and an inverted arch to an excavation surface;
s10: excavating a second side (10) of the lower part, and applying a primary support (11) and an inverted arch to an excavated surface;
s11: constructing an inverted arch and constructing a secondary lining.
7. The construction method according to claim 6, wherein before excavating the upper first sidewall pit upper step (2), the upper first sidewall pit lower step (3), the upper second sidewall pit upper step (4) and the upper second sidewall pit lower step (5), a row of guide pipes (12) are firstly applied to the outer edges of the first sidewall pit upper step, the upper first sidewall pit upper step (3), the upper second sidewall pit upper step (4) and the upper second sidewall pit lower step (5) and then excavated.
8. The construction method according to claim 6, wherein after excavating the upper first sidewall pit upper step (2), the upper first sidewall pit lower step (3), the upper second sidewall pit upper step (4) and the upper second sidewall pit lower step (5), temporary arches (13) are formed at the bottom of the first sidewall pit upper step, the bottom of the upper first sidewall pit upper step (3), the bottom of the upper second sidewall pit upper step (4) and the bottom of the upper second sidewall pit lower step (5).
9. The construction method according to any one of claims 6 to 8, wherein the upper first sidewall pit upper step (2), the upper first sidewall pit lower step (3), the upper second sidewall pit upper step (4), the upper second sidewall pit lower step (5) and the upper middle trough (6) are simultaneously constructed in left, middle and right; the first side (7) of the middle part and the second side (8) of the middle part are constructed at the left side and the right side simultaneously; the lower first side (9) and the lower second side (10) are constructed at the left side and the right side simultaneously.
10. The construction method as claimed in any one of claims 6 to 8, wherein the cross-sectional area of the large-section tunnel of the water-rich weak surrounding rock is 120-180m2The water-rich weak surrounding rock refers to a water-rich completely weathered granite altered zone, a third series of non-diagenetic sand layer and a water-rich fault.
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