Anti-interference construction method for small-pitch bridge-tunnel combined structure

Abstract

The application relates to the technical field of bridge and tunnel construction, in particular to a small-clearance bridge and tunnel combined structure anti-interference construction method. The bridge and tunnel combined structure comprises a bridge and a tunnel arranged in parallel along an axial direction; the tunnel comprises a tunnel vertical excavation section adopting a first slope and a second vertical excavation of a tunnel foundation pit and a tunnel slope excavation section adopting multi-stage slope excavation of a tunnel foundation pit; the bridge comprises a bridge slope excavation section adopting slope excavation of a pile cap foundation pit and a bridge vertical excavation section adopting vertical excavation of a pile cap foundation pit; the anti-interference construction method comprises the following steps: S1, setting the depth of the tunnel foundation pit slope excavation to be greater than the pile cap embedded depth of the bridge slope excavation section; after the tunnel foundation pit is excavated and stabilized, the bridge pile foundation is constructed; S2, after the bridge pile foundation construction is completed, the tunnel main body structure construction and the pile cap construction of the bridge slope excavation section are simultaneously performed; S4, after the tunnel foundation pit backfilling is completed, the construction of the remaining structure of the bridge is performed, the pile cap construction of the bridge slope excavation section is prepositioned, and the construction speed is improved.

Description

Technical Field

[0001] This application relates to the field of bridge and tunnel construction technology, and in particular to a method for preventing interference during the construction of a bridge and tunnel composite structure with small clearance. Background Technology

[0002] With the continuous expansion and extension of infrastructure construction in my country, the combined design of infrastructure structures, such as bridge-tunnel composite structures, is increasing based on functional and traffic requirements. Existing construction schemes for bridge-tunnel composite structures are often based on tunnel construction under existing bridge conditions or bridge construction under existing tunnel conditions. There is little attention paid to the simultaneous construction of bridge-tunnel composite structures, especially considering the stability of the foundation pit, working face, and pile bearing capacity of bridge-tunnel composite structures with small clearances. These factors can influence each other during foundation pit excavation or structural pouring. How to ensure construction speed while minimizing mutual interference has become a pressing technical problem to be solved.

[0003] Therefore, there is a need to provide an improved technical solution that addresses the shortcomings of the existing technology. Summary of the Invention

[0004] The purpose of this application is to provide a method for preventing interference during the construction of bridge-tunnel composite structures with small clearance, so as to solve or alleviate the problems existing in the prior art.

[0005] To achieve the above objectives, this application provides the following technical solution:

[0006] A method for preventing interference during the construction of a bridge-tunnel composite structure with small clearance, wherein the bridge-tunnel composite structure includes a bridge and a tunnel arranged in parallel along the axial direction;

[0007] The tunnel includes a vertical excavation section where the tunnel foundation pit is excavated vertically after sloping, and a sloping excavation section where the tunnel foundation pit is excavated using multi-stage sloping methods.

[0008] The bridge includes a bridge slope excavation section that uses sloping excavation of the pier foundation pit and a bridge vertical excavation section that uses vertical excavation of the pier foundation pit.

[0009] The anti-interference construction method includes:

[0010] Step S1: Set the depth of the tunnel foundation pit excavation slope to be greater than the burial depth of the bridge foundation excavation slope section. After the tunnel foundation pit is excavated and stabilized, construct the bridge pile foundation.

[0011] Step S2: After the bridge pile foundation construction is completed, the main structure construction of the tunnel and the pier construction of the bridge slope excavation section are carried out simultaneously.

[0012] Step S4: After the tunnel foundation pit is backfilled, the construction of the remaining bridge structure will proceed.

[0013] The above-described method for preventing interference in the construction of a bridge-tunnel composite structure with small clearance is preferably described in step S2, in which the construction of the main tunnel structure specifically involves: first, constructing the main tunnel structure corresponding to the vertical excavation section of the bridge, and then constructing the main tunnel structure corresponding to the slope excavation section of the bridge.

[0014] The above-described method for preventing interference during construction of a bridge-tunnel composite structure with small clearance is preferably further comprising:

[0015] Step S3: After the main structure of the tunnel is constructed, the tunnel foundation pit is backfilled.

[0016] The above-described method for preventing interference during construction of a bridge-tunnel composite structure with small clearance is preferably described as follows:

[0017] In step S3, after the construction of the corresponding tunnel main structure is completed, the tunnel foundation pit of the corresponding section is backfilled.

[0018] In step S4, after the backfilling of the tunnel foundation pit of the corresponding section is completed, the construction of the remaining bridge structure of the corresponding section will proceed.

[0019] The above-described method for preventing interference during construction of a bridge-tunnel composite structure with small clearance is preferably described as follows:

[0020] For sloping excavation of foundation pits and tunnel pits, a combined support structure of shotcrete, soil nailing, and steel mesh is adopted.

[0021] The above-described method for preventing interference during construction of a bridge-tunnel composite structure with small clearance is preferably described as follows:

[0022] The vertically excavated foundation pit adopts a combined support structure of steel sheet piles and steel braces;

[0023] The vertically excavated tunnel foundation pit adopts a support structure combining bored piles and steel supports.

[0024] The above-described method for preventing interference during construction of a bridge-tunnel composite structure with small clearance is preferably described as follows:

[0025] The main structure of the tunnel in the slope excavation section includes an inverted arch and an arch crown;

[0026] The main structure of the vertically excavated section of the tunnel includes an inverted arch, sidewalls, and an arch crown;

[0027] The invert arch section is constructed using an invert arch formwork and mechanical hoisting. The arch crown of the tunnel slope excavation section is constructed using an inner formwork trolley and an outer formwork trolley in combination. The sidewalls and arch crown of the tunnel vertical excavation section are constructed using an inner formwork trolley and a simple outer formwork in combination.

[0028] The above-described method for preventing interference during construction of a bridge-tunnel composite structure with small clearance is preferably described as follows:

[0029] The construction sequence of the main tunnel structure in the slope excavation section is as follows: invert waterproof layer, invert, arch crown, and arch crown waterproof layer.

[0030] The construction sequence of the main structure of the vertically excavated section of the tunnel is as follows: waterproof layer of the invert arch, invert arch, waterproof layer of the side wall, side wall, arch crown, and waterproof layer of the arch crown.

[0031] The above-described method for preventing interference during construction of a bridge-tunnel composite structure with small clearance is preferably described as follows:

[0032] The waterproof layer of the inverted arch and the waterproof layer of the side walls are constructed using the pre-laid reverse bonding method, while the waterproof layer of the arch top is constructed using the post-laid forward bonding method.

[0033] As described above, in a method for preventing interference in the construction of a bridge-tunnel combination structure with small clearance, preferably, the bridge is a double-span bridge, including a left-span bridge located far from the tunnel and a right-span bridge located close to the tunnel.

[0034] The construction of the left bridge was carried out simultaneously with the construction of the tunnel;

[0035] The right-hand bridge is constructed according to steps S1, S2, and S4.

[0036] Compared with the closest prior art, the technical solution of this application has the following beneficial effects:

[0037] Considering the mutual impact of the foundation pit excavation and the tunnel foundation pit excavation on each other's construction, on the one hand, the construction of the bridge pile foundation is carried out only after the tunnel foundation pit is excavated and stabilized, in order to avoid the soil structure being loosened due to the tunnel foundation pit excavation, which would affect the bearing capacity of the bridge pile foundation; on the other hand, based on the need to improve construction speed, whether it is the vertical excavation section or the sloping excavation section of the tunnel, the tunnel foundation pit is first sloping excavated to a certain depth, and the depth of the sloping excavation of the tunnel foundation pit is greater than the foundation pit burial depth of the sloping excavation section of the bridge. This allows the construction of the foundation pit using the same sloping excavation method to be unaffected by the tunnel foundation pit excavation, realizing the pre-construction of the foundation pit of the sloping excavation section of the bridge, thereby reducing the constraints of the tunnel foundation pit excavation on the construction of one side of the bridge and improving the construction speed. Attached Figure Description

[0038] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. Wherein:

[0039] Figure 1 This is a schematic diagram of the cross-sectional structure of a bridge-tunnel combination structure with small clearance provided according to some embodiments of this application;

[0040] Figure 2This is a schematic diagram of the bridge pier construction for slope excavation section according to some embodiments of this application;

[0041] Figure 3 This is a schematic diagram of the construction of the main structure of the vertical excavation section of a tunnel according to some embodiments of this application;

[0042] Figure 4 This is a schematic diagram of the main structure construction of the tunnel slope excavation section according to some embodiments of this application.

[0043] Explanation of reference numerals in the attached figures:

[0044] 1. Left bridge; 2. Right bridge; 3. Tunnel; 4. Main structure of tunnel; 5. Tunnel slope excavation section; 6. Tunnel vertical excavation section; 7. Pile foundation; 8. Abutment; 9. Invert arch; 10. Side wall; 11. Arch crown; 12. Bridge slope excavation section. Detailed Implementation

[0045] The present application will now be described in detail with reference to the accompanying drawings and embodiments. Various examples are provided by way of explanation and not by way of limitation. In fact, those skilled in the art will recognize that modifications and variations can be made to the present application without departing from the scope or spirit thereof. For example, a feature shown or described as part of one embodiment may be used in another embodiment to produce yet another embodiment. Therefore, it is desirable that the present application encompass such modifications and variations that fall within the scope of the appended claims and their equivalents.

[0046] In the following description, the terms "first / second / third" are used merely to distinguish similar objects and do not represent a specific order of objects. It is understood that "first / second / third" may be interchanged in a specific order or sequence where permitted, so that the embodiments of this application described herein can be implemented in an order other than that illustrated or described herein.

[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The terminology used herein is for the purpose of describing embodiments of this disclosure only and is not intended to limit this disclosure.

[0048] In the description of this application, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," and "bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and do not require that this application be constructed and operated in a specific orientation, and therefore should not be construed as limiting this application. The terms "connected," "linked," and "set up" used in this application should be interpreted broadly. For example, they can refer to fixed connections or detachable connections; direct connections or indirect connections through intermediate components; wired connections, radio connections, or wireless communication signal connections. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0049] The following will be combined with the appendix Figure 1-4 This application provides a more detailed description of a method for preventing interference during the construction of a bridge-tunnel composite structure with small clearance.

[0050] A method for preventing interference in the construction of a bridge-tunnel composite structure with small clearance, wherein the bridge-tunnel composite structure includes a bridge and a tunnel 3 arranged in parallel along the axial direction;

[0051] Tunnel 3 includes a vertical excavation section 6 that adopts a first-slope-then-vertical-excavation method for the tunnel foundation pit and a multi-stage slope-then-excavation section 5 for the tunnel foundation pit.

[0052] The bridge includes a bridge slope excavation section 12 that uses slope excavation to create the foundation pit of the 8th pier and a bridge vertical excavation section that uses vertical excavation to create the foundation pit of the 8th pier.

[0053] Methods to prevent interference during construction include:

[0054] Step S1: Set the depth of the slope excavation of the tunnel 3 foundation pit to be greater than the burial depth of the bridge pier 8 in the slope excavation section 12. After the tunnel 3 foundation pit is excavated and stabilized, construct the bridge pile foundation 7.

[0055] Step S2: After the bridge pile foundation 7 is completed, the tunnel main structure 4 and the bridge slope excavation section 12 abutment 8 are constructed simultaneously.

[0056] Step S4: After the backfilling of the foundation pit of Tunnel 3 is completed, the construction of the remaining bridge structure will proceed.

[0057] In a specific embodiment of this application, the bridge and tunnel 3 are arranged horizontally side by side along the axial direction. The excavation depth of the bridge's foundation pit 8 is between 3m and 9m, and the excavation depth of the tunnel 3's foundation pit is between 10m and 24m. Considering the stability of the foundation pits and the actual conditions of the working face, the foundation pits of the foundation 8 are excavated with slope excavation and supplemented with corresponding support structures when the excavation depth is between 3m and 5m, and with vertical excavation and supplemented with corresponding support structures when the excavation depth is between 5m and 9m. Furthermore, considering the mutual impact of the foundation pit excavation of the foundation 8 and the tunnel 3's foundation pit on each other's construction, the construction of the bridge pile foundation 7 is carried out only after the tunnel 3's foundation pit is excavated and stabilized, to avoid the soil structure loosening caused by the tunnel 3's foundation pit excavation, which could then affect... The bearing capacity of bridge pile foundation 7; on the other hand, based on the need to improve construction speed, both the vertical excavation section 6 and the slope excavation section 5 of the tunnel are designed with a certain depth of slope excavation of the tunnel 3 foundation pit, and the slope excavation depth of the tunnel 3 foundation pit is greater than the burial depth of the pier cap 8 of the bridge slope excavation section 12. This allows the construction of the pier cap 8, which also adopts slope excavation, to be unaffected by the excavation of the tunnel 3 foundation pit, realizing the pre-construction of the pier cap 8 of the bridge slope excavation section 12, so as to minimize the constraints of the tunnel 3 foundation pit excavation on the construction of the bridge on one side. The construction of the pier cap 8 includes the excavation and support of the pier cap 8 foundation pit, reinforcement binding and formwork installation, concrete pouring, formwork removal and curing, and backfilling of the pier cap 8.

[0058] In step S2, the construction of the tunnel main structure 4 is specifically as follows: first, the construction of the tunnel main structure 4 corresponding to the vertical excavation section of the bridge is carried out, and then the construction of the tunnel main structure 4 corresponding to the slope excavation section 12 of the bridge is carried out.

[0059] After the bridge pile foundation 7 is completed, the construction of the pier cap 8 of the bridge slope excavation section 12 can be carried out. Correspondingly, for the construction of tunnel 3, based on the consideration of reducing the mutual construction interference between tunnel 3 and bridge, the construction of the tunnel main structure 4 corresponding to the vertical excavation section of the bridge is carried out first. After the construction of the pier cap 8 of the bridge slope excavation section 12 is completed, the construction of the tunnel main structure 4 corresponding to the bridge slope excavation section 12 is carried out.

[0060] Methods to prevent interference during construction also include:

[0061] Step S3: After the main tunnel structure 4 is completed, backfilling of the tunnel 3 foundation pit will be carried out.

[0062] After the main construction of Tunnel 3 is completed, the foundation pit of Tunnel 3 will be backfilled in a timely manner. On the one hand, this will provide a working surface for the construction of the remaining bridge structure. On the other hand, the backfilled soil has strong structural stability to ensure the bearing capacity of the corresponding supports of the remaining bridge structure.

[0063] In a specific embodiment of this application, the backfill soil above the main tunnel structure 4 is symmetrically layered and compacted, with each layer not exceeding 0.3m in thickness and the height difference between the backfill soil on both sides not exceeding 0.5m. After backfilling to the arch crown 11, it should be fully covered and then filled upwards in layers; random dumping is strictly prohibited. Steps should be set at the joints of the segmented backfilling of the foundation pit, with a step width not less than 1m and a height not exceeding 0.5m. During foundation pit backfilling, machinery or equipment must not collide with the waterproof layer of tunnel 3. Small machinery should be used for compaction within 1m of the sides and top of the main tunnel structure 4, as well as around underground pipelines. The mechanical construction load for backfilling the tunnel top of 3 should not exceed 20kPa, and vibration mode is prohibited for compaction.

[0064] In step S3, after the construction of the corresponding tunnel main structure 4 is completed, the foundation pit of the corresponding section of tunnel 3 is backfilled.

[0065] In step S4, after the backfilling of the foundation pit of the corresponding section of tunnel 3 is completed, the construction of the remaining structure of the bridge in the corresponding section will begin.

[0066] In a specific embodiment of this application, the bridge abutment 8 and the tunnel main structure 4 are constructed in segments according to the sequence of step S2. Correspondingly, following the aforementioned segmented construction method, after the tunnel main structure 4 corresponding to the vertical excavation segment of the bridge is completed, the corresponding tunnel 3 foundation pit is backfilled, without waiting for the completion of the entire tunnel main structure 4 and the completion of the entire tunnel 3 foundation pit. This arrangement maximizes the overlap between the construction of tunnel 3 and the bridge. By placing the construction of the tunnel main structure 4 corresponding to the vertical excavation segment of the bridge before the construction of the tunnel main structure 4 corresponding to the slope excavation segment 12 of the bridge, on the one hand, as mentioned above, the impact of the construction of the abutment 8 in the slope excavation segment 12 on the construction of tunnel 3 can be reduced; on the other hand, it can provide working conditions for the construction of the abutment 8 and other remaining structures in the vertical excavation segment of the bridge as early as possible, while achieving interference prevention and efficiency improvement. The remaining bridge structures in the vertical excavation segment of the bridge include the abutment 8, piers, and bridge deck, while the remaining bridge structures in the slope excavation segment 12 of the bridge include piers and bridge deck.

[0067] The foundation pits of the 8 foundation pits and the 3 tunnel pits, which were excavated by slope excavation, adopted a combined support structure of shotcrete, soil nailing and steel mesh.

[0068] In the specific embodiments of this application, the slope ratio for the 8 bridge abutment pits and 3 tunnel pits is 1:1. Excavators are primarily used for pit excavation and loading, employing a toppling method to transfer the excavated material before loading and transporting it off-site. During excavation, timely application of wire mesh and shotcrete is carried out to ensure slope stability and prevent slope collapse caused by constructing support only at the toe of the slope. The principle of "layered excavation and prohibition of over-excavation" is strictly adhered to during excavation. The layer height is determined based on specific geological conditions, generally ranging from 1 to 2 meters.

[0069] Shotcrete must be applied using a wet spraying process. The concrete grade is C25. The process is carried out in sections and segments, with the spraying sequence within the same section from top to bottom. The total thickness of the sprayed concrete is 10cm, applied in two stages. The first spray is 3cm-4cm thick. After the first spray is completed and the strength reaches 70% of the design strength, soil nails are driven into the slope and steel mesh is installed. The second spray is then applied, with a thickness of 6cm-7cm.

[0070] The vertically excavated foundation pit No. 8 adopts a combined support structure of steel sheet piles and steel braces;

[0071] The vertically excavated Tunnel 3 foundation pit adopts a support structure combining bored piles and steel supports.

[0072] Based on the different required support strengths for the foundation pits of 8 and 3, and considering the depth of the foundation pits of 8 and 3, in the specific embodiments of this application, steel sheet piles with a length of 12m are selected for the foundation pits of 8 with an excavation depth between 5m and 8m, and steel sheet piles with a length of 18m are selected for the foundation pits of 8 with an excavation depth between 8m and 9m; the length of the bored piles for the foundation pits of 3 is between 21m and 35m.

[0073] The overall excavation sequence of the foundation pit follows the principle of "intermediate trenching, symmetrical excavation on both sides, section excavation followed by section support, and timely erection of steel supports." This requires close coordination among excavation, support, monitoring and measurement, and structural construction. When the excavation reaches 50cm below the steel supports, steel walers and supports are installed. When the excavation approaches the design elevation, a 30cm section is left for manual excavation using shovels, picks, and other tools. A ring-shaped drainage ditch is constructed at the bottom of the pit, and a sump is set at the lowest point to collect and pump accumulated water into existing ditches outside the pit. To reduce the weakening of the foundation pit's bearing capacity due to prolonged exposure, disturbance, or soaking, a concrete cushion layer is poured promptly.

[0074] The main tunnel structure 4 of the tunnel slope excavation section 5 includes an invert arch 9 and an arch crown 11;

[0075] The main tunnel structure 4 of the vertical excavation section 6 includes an inverted arch 9, sidewalls 10, and an arch crown 11;

[0076] The invert arch section 9 was constructed using an invert arch 9 arc formwork and mechanical hoisting. The arch crown 11 of the tunnel slope excavation section 5 was constructed using an inner formwork trolley and an outer formwork trolley in combination. The sidewalls 10 and arch crown 11 of the tunnel vertical excavation section 6 were constructed using an inner formwork trolley and a simple outer formwork in combination.

[0077] In a specific embodiment of this application, the reinforcing bars of the invert arch 9 are centrally processed and delivered to the site by an intelligent reinforcing bar processing and distribution center. The reinforcing bars are hoisted to the working face in the foundation pit by a crane. The arch formwork of the invert arch 9 is hoisted piece by piece by a crane and supported and positioned by positioning reinforcing bars. The concrete of the invert arch 9 is poured in sections with a concrete grade of C40 and is poured by a pump truck. During the pouring, the concrete is poured symmetrically and continuously from the center of the invert arch 9 to both sides, and the process is completed in one go.

[0078] Considering the construction conditions of the main tunnel structure 4, the working space of the tunnel slope excavation section 5 is relatively large, so an inner formwork trolley and an outer formwork trolley are used in combination for the pouring of the arch 11. The working space of the vertical excavation section 6 is limited, so an inner formwork trolley and a simple outer formwork are used in combination for the pouring of the sidewalls 10 and the arch 11. The reinforcement binding of the sidewalls 10 and the arch 11 is specifically carried out with the assistance of a reinforcement installation trolley. Specifically, a crane is first used to lower the reinforcement into the corresponding working face in the tunnel 3 foundation pit. After the reinforcement installation trolley is in place, it is precisely positioned to ensure the accuracy of the reinforcement binding.

[0079] The construction sequence of the main tunnel structure 4 of the tunnel slope excavation section 5 is as follows: waterproof layer of invert arch 9, invert arch 9, arch crown 11, waterproof layer of arch crown 11.

[0080] The construction sequence of the main tunnel structure 4 of the vertical excavation section 6 is as follows: waterproof layer of invert arch 9, waterproof layer of side wall 10, side wall 10, arch crown 11, waterproof layer of arch crown 11.

[0081] In addition to considering the mutual interference generated during the construction of tunnel 3 and bridge, based on the actual usage requirements of the bridge, the main structure of tunnel 4 needs to have good waterproof performance to ensure its normal operation, so as to achieve the anti-interference effect during the actual operation of the bridge-tunnel combination structure after it is put into use. Specifically, the main structure of tunnel 4 is provided with a fully enclosed, separate waterproof layer along the circumference. Through the bonding and close adhesion between the waterproof membrane and the cast-in-place concrete structure, waterproof sealing without dead corners is achieved, preventing water seepage during operation.

[0082] In a specific embodiment of this application, the waterproof layer of the invert arch 9 consists of a 200mm thick C20 concrete pad, a 1.2mm thick single-sided self-adhesive waterproof board, a 400g / m2 non-woven fabric, and a 50mm thick C40 fine stone concrete protective layer; the waterproof layer of the side wall 10 consists of a 100mm thick C25 sprayed concrete, a 400g / m2 non-woven fabric, and a 1.2mm thick single-sided reverse-adhesive waterproof board; and the waterproof layer of the arch crown 11 consists of a 2.5mm thick single-component polyurethane waterproof coating, a 1.2mm thick single-sided reverse-adhesive waterproof board, and an 80mm thick C40 fine stone concrete protective layer.

[0083] The waterproof layer 9 of the invert arch and the waterproof layer 10 of the side wall are constructed using the pre-laid reverse bonding method, while the waterproof layer 11 of the arch top is constructed using the post-laid forward bonding method.

[0084] In a specific embodiment of this application, the waterproofing layers of the invert arch 9 and the sidewall 10 are constructed using a pre-laying reverse bonding method. Specifically, the non-bonding surface of the waterproofing membrane is laid on the side of the invert arch 9 cushion layer, spreading from the bottom of the invert arch 9 to both sides. A 50mm fine stone concrete protective layer is laid on the bonding surface of the waterproofing membrane, after which the main structure can be constructed. For the waterproofing layer of the sidewall 10, the bonding surface of its waterproofing membrane is also set on the side closer to the main structure. The waterproofing layer of the arch crown 11 is constructed using a post-laying positive bonding method. Specifically, the concrete surface of the arch crown 11 is first ground and cleaned and smoothed with epoxy mortar to ensure that the concrete base surface of the arch crown 11 is flat and clean. To ensure good adhesion between the concrete base surface and the waterproofing coating, epoxy sealing paint is sprayed on the concrete surface in time. After the sealing paint dries completely, a single-component polyurethane waterproofing coating is mechanically sprayed twice, and then the waterproofing membrane is laid. The bonding surface of the waterproofing membrane is closely adhered to the polyurethane waterproofing coating. An 80mm thick fine stone concrete protective layer is directly applied outside the waterproofing layer, and finally the top backfill layer of the tunnel main structure 4 is constructed.

[0085] The bridge is a double-span bridge, consisting of a left span bridge 1 located away from tunnel 3 and a right span bridge 2 located closer to tunnel 3;

[0086] Construction of the left bridge 1 and tunnel 3 were carried out simultaneously;

[0087] The right span of bridge 2 shall be constructed in accordance with steps S1, S2 and S4.

[0088] In a specific embodiment of this application, the left bridge 1, the right bridge 2, and the tunnel 3 are arranged horizontally side by side along the axial direction. The construction of the left bridge 1 and the tunnel 3 do not affect each other. Setting them to be constructed simultaneously can improve the overall construction speed. On the other hand, with the left bridge 1 and tunnel 3 under construction simultaneously, the right bridge 2 is constructed according to steps S1, S2, and S4, so that the construction progress of the left bridge 1 is ahead of that of the right bridge 2. This avoids conflicts on the work surface caused by the simultaneous construction of the left bridge 1 and the right bridge 2, minimizes the mutual constraints between the construction of the left bridge 1 and the right bridge 2, fully realizes the cross-operation of the bridge-tunnel combination structure, improves the construction speed, and avoids the waste of manpower, time, and other resources caused by idle work.

[0089] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for preventing interference during construction of a bridge-tunnel composite structure with small clearance, characterized in that, The bridge-tunnel combination structure includes bridges and tunnels arranged side by side along the axial direction; The tunnel includes a vertical excavation section where the tunnel foundation pit is excavated vertically after sloping, and a sloping excavation section where the tunnel foundation pit is excavated using multi-stage sloping methods. The bridge includes a bridge slope excavation section that uses sloping excavation of the pier foundation pit and a bridge vertical excavation section that uses vertical excavation of the pier foundation pit. The anti-interference construction method includes: Step S1: Set the depth of the tunnel foundation pit slope excavation in both the vertical excavation section and the slope excavation section of the tunnel to be greater than the burial depth of the bridge foundation in the slope excavation section. After the tunnel foundation pit is excavated and stabilized, construct the bridge pile foundation. Step S2: After the bridge pile foundation construction is completed, the main structure construction of the tunnel and the pier construction of the bridge slope excavation section are carried out simultaneously. In step S2, the construction of the tunnel main structure specifically involves: first, constructing the tunnel main structure corresponding to the vertical excavation section of the bridge, and then constructing the tunnel main structure corresponding to the slope excavation section of the bridge. Step S3: After the main tunnel structure is constructed, the tunnel foundation pit is backfilled. In step S3, after the construction of the corresponding tunnel main structure is completed, the tunnel foundation pit of the corresponding section is backfilled. Step S4: After the tunnel foundation pit is backfilled, the construction of the remaining bridge structure will proceed. In step S4, after the backfilling of the tunnel foundation pit of the corresponding section is completed, the construction of the remaining bridge structure of the corresponding section will proceed. The remaining structure of a bridge in a vertically excavated section includes abutments, piers, and bridge deck; the remaining structure of a bridge in a sloped excavation section includes piers and bridge deck. Both the sloping excavation of the foundation pit and the sloping excavation of the tunnel pit adopt a combined support structure of shotcrete, soil nailing and steel mesh. The vertically excavated foundation pit adopts a combined support structure of steel sheet piles and steel braces; The vertically excavated tunnel foundation pit adopts a support structure combining bored piles and steel supports.

2. The method for preventing interference during construction of a bridge-tunnel composite structure with small clearance as described in claim 1, characterized in that, The main structure of the tunnel in the slope excavation section includes an inverted arch and an arch crown; The main structure of the vertically excavated section of the tunnel includes an inverted arch, sidewalls, and an arch crown; The invert arch is constructed using an invert arch arc mold and mechanical hoisting. The arch top of the tunnel slope excavation section is constructed using an inner mold trolley and an outer mold trolley in combination. The sidewalls and arch top of the tunnel vertical excavation section are constructed using an inner mold trolley and a simple outer mold in combination.

3. The method for preventing interference during construction of a bridge-tunnel composite structure with small clearance as described in claim 2, characterized in that, The construction sequence of the main tunnel structure in the slope excavation section is as follows: invert waterproof layer, invert, arch crown, and arch crown waterproof layer. The construction sequence of the main structure of the vertically excavated section of the tunnel is as follows: waterproof layer of the invert arch, invert arch, waterproof layer of the side wall, side wall, arch crown, and waterproof layer of the arch crown.

4. The method for preventing interference during construction of a bridge-tunnel composite structure with small clearance as described in claim 3, characterized in that, The waterproof layer of the inverted arch and the waterproof layer of the side walls are constructed using the pre-laid reverse bonding method, while the waterproof layer of the arch top is constructed using the post-laid forward bonding method.

5. A method for preventing interference during construction of a bridge-tunnel composite structure with small clearance as described in any one of claims 1-4, characterized in that, The bridge is a two-lane bridge, consisting of a left lane located away from the tunnel and a right lane located closer to the tunnel. The construction of the left bridge was carried out simultaneously with the construction of the tunnel; The right-hand bridge is constructed according to steps S1, S2, and S4.

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