Super-shallow buried excavation tunnel with protection structure and small net distance side-penetrating pier platform
By employing a protective structure composed of rigidly connected isolation piles, cap beams, and cross braces during tunnel construction, combined with backfill concrete and advanced support, the problem of insufficient rigidity of traditional isolation piles was solved, achieving effective protection of the bridge and construction safety control.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- CHINA RAILWAY CHONGQING SURVEYING DESIGN RES INST CO LTD
- Filing Date
- 2025-09-29
- Publication Date
- 2026-07-24
AI Technical Summary
Traditional isolation pile protection structures lack sufficient stiffness under ultra-shallow burial and extremely small clearance conditions, making it difficult to effectively control the impact of tunnel construction on bridges. Furthermore, they lack a systematic force transfer mechanism, affecting project progress and cost.
The protective structure, consisting of rigidly connected first and second rows of isolation piles, capping beams, and cross braces, enhances overall rigidity through integral casting. Backfill concrete is then filled into the structure to seal the ground structure layer. Combined with advanced support and tunnel lining construction, an inverted U-shaped protective structure is formed.
Effectively control the range of ground deformation caused by tunnel construction, ensure tunnel construction safety, reduce adverse effects on bridges, improve project progress and reduce costs.
Smart Images
Figure CN224550111U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of tunnel engineering technology, and relates to a protective structure and an ultra-shallow buried tunnel with extremely small clearance to the side of the bridge pier. Background Technology
[0002] With the rapid growth in demand for urban underground space development, tunnel engineering faces increasingly complex conditions requiring passage through existing building structures. Especially in core urban areas, newly constructed tunnels often need to pass alongside operating bridge structures with minimal clearance, posing a significant challenge to tunnel construction safety and the protection of existing structures. While traditional shallow-buried tunneling methods offer the advantage of minimal impact on surface traffic, construction under ultra-shallow conditions results in large-scale ground deformation with a wide impact range, easily adversely affecting the foundations of adjacent bridge piers and abutments. The redistribution of ground stress caused by tunnel excavation is transmitted to bridge pile foundations through the soil, leading to additional deformation and internal forces in the pile foundations. In severe cases, this can cause excessive deformation or even instability of the bridge structure. Therefore, isolation piles are generally used to protect adjacent bridge piers and abutments before tunnel construction.
[0003] Currently, traditional isolation pile protection structures have the following drawbacks: 1. Insufficient rigidity and poor overall integrity of the isolation piles make it difficult to effectively control the impact of tunnel construction on bridge abutments, especially under conditions of ultra-shallow burial and extremely small clearance. Existing isolation pile protection structures often cannot simultaneously meet the dual requirements of tunnel construction safety and bridge protection. 2. Traditional isolation pile protection structures lack a systematic force transfer mechanism, requiring frequent adjustments to support parameters during construction, which seriously affects project progress and increases construction costs. Utility Model Content
[0004] The purpose of this invention is to address the aforementioned problems in existing technologies by proposing a protective structure with high overall rigidity that can effectively control the range of formation deformation.
[0005] A method for creating an ultra-shallow buried tunnel with minimal clearance to pass through bridge piers and abutments was also proposed.
[0006] The objective of this utility model can be achieved through the following technical solutions:
[0007] The protective structure includes a first row of isolation piles, a first cap beam rigidly connected to the top of the first row of isolation piles, a second row of isolation piles, a second cap beam rigidly connected to the top of the second row of isolation piles, and a number of horizontal braces disposed between the first cap beam and the second cap beam. One end of the horizontal brace is rigidly connected to the first cap beam, and the other end of the horizontal brace is rigidly connected to the second cap beam.
[0008] During construction, the main reinforcement bars of the first and second rows of isolation piles should extend into the capping beam according to the structural requirements, and then be cast as a whole. The first capping beam, the second capping beam, and the cross brace are perpendicular and rigidly connected, and the main reinforcement bars of the cross brace should extend into the capping beam according to the structural requirements.
[0009] The longitudinal spacing and number of the first and second rows of isolation piles along the new tunnel can be adjusted according to the relative relationship between the new tunnel and the structure, the geological conditions of the construction area, the surrounding environment, and the size of the isolation piles.
[0010] In the aforementioned protective structure, the area enclosed by the first capping beam, the second capping beam, and the cross bracing is filled with backfill concrete. This backfill concrete fills the area enclosed by the first capping beam, the second capping beam, and the cross bracing, enhancing structural rigidity and sealing the above-ground structural layers to prevent groundwater infiltration and ensure the safety of the tunnel structure in the later stages. When the surface is uneven, backfill concrete can be used as a subbase to fill the gaps between the first capping beam, the second capping beam, and the ground surface.
[0011] In the above-mentioned protective structure, the first row of isolation piles and the second row of isolation piles are manually excavated piles, and the cross-sectional form of the first row of isolation piles and the second row of isolation piles is square pile.
[0012] In the above-mentioned protective structure, the first row of isolation piles and the second row of isolation piles are bored piles, and the cross-sectional shape of the first row of isolation piles and the second row of isolation piles is a circular pile.
[0013] In the aforementioned protective structure, the first and second rows of isolation piles are prefabricated in the factory. When the clearance between the bottom of the main bridge structure and the ground is sufficient, the first and second rows of isolation piles are prefabricated in the factory and then hoisted into place.
[0014] In the aforementioned protective structure, the first and second rows of isolation piles are cast-in-place isolation piles. When the clearance between the bottom of the main bridge structure and the ground is insufficient to meet the hoisting requirements, the isolation pile reinforcement cages need to be hoisted in sections according to factors such as site clearance and site conditions, and then the isolation piles are cast-in-place.
[0015] The ultra-shallow buried tunnel with minimal clearance passing through bridge piers and abutments includes a newly constructed tunnel and the aforementioned protective structure. The newly constructed tunnel is located within the protective structure. The newly constructed tunnel is constructed using the cut-and-cover method, eliminating the need for arch wall anchors, and pre-support is constructed before excavation. Pre-support is generally a pre-support pipe jacking or a pre-support large pipe roof.
[0016] During construction, the first row of isolation piles, the second row of isolation piles, the first capping beam, the second capping beam, and the cross bracing are excavated and poured as a whole. The isolation piles should extend a certain distance below the bottom of the new tunnel invert arch and be embedded in the bedrock, depending on the geological conditions. After the construction is completed, the structural gaps are filled with backfill concrete to form an inverted U-shaped protective structure with a certain rigidity. Then, the advanced support is constructed to form a reinforcement ring. After that, the new tunnel is excavated and the tunnel lining is constructed.
[0017] In the aforementioned ultra-shallow buried tunnels with minimal clearance passing through bridge piers and abutments, when the existing bridge piers and abutments are pile foundations, the depth to which the first row of isolation piles and the second row of isolation piles extend below the pile foundation of the bridge pier and abutment shall not be less than 5m.
[0018] When the geological conditions of the construction area are good, bridge piers and abutments are generally shallow foundations; only when the geological conditions of the construction area are poor will bridge piers and abutments use pile foundations.
[0019] Before constructing a new tunnel, settlement and tilt detection points should be set up at relevant locations on the bridge piers and abutments. To ensure the accuracy and timeliness of the monitoring data, automated monitoring is generally used.
[0020] In the aforementioned ultra-shallow buried tunnel with extremely small clearance between the bridge piers and the tunnel, the first and second rows of isolation piles have a lateral distance of 0.5m to 1.0m from the outer contour of the newly built tunnel.
[0021] In the aforementioned ultra-shallow buried tunnels with minimal clearance between the tunnel piers and abutments, the first and second rows of isolation piles should extend at least 2 meters below the invert of the newly constructed tunnel. When the first and second rows of isolation piles need to pass through a thick fill layer, the lower ends of the first and second rows of isolation piles should be embedded in the bedrock.
[0022] Compared with the prior art, the present invention has the following advantages:
[0023] Compared with traditional isolation piles, the isolation piles, cap beams, and cross braces are rigidly connected and cast as a whole, which has strong overall rigidity. This effectively limits the deformation of the surrounding rock and soil caused by tunnel excavation, ensuring the safety of tunnel construction. At the same time, it controls the range of stratum deformation and ensures the safety of bridge operation. The backfill concrete fills the structure and surface voids, preventing surface water infiltration. This can greatly reduce the risk of shallow buried tunnels passing through bridge piers and abutments at extremely small clearances. Attached Figure Description
[0024] Figure 1 This is a schematic diagram of the protective structure and the newly built tunnel.
[0025] Figure 2 This is a schematic diagram of the cross-sectional structure of the protective structure and the newly built tunnel;
[0026] Figure 3 It is a schematic diagram of the protective structure, the newly built tunnel, and the existing bridge.
[0027] Figure 4 This is a schematic diagram of the longitudinal section of the protective structure and the newly built tunnel.
[0028] In the diagram: 1. First row of isolation piles; 2. Second row of isolation piles; 3. First capping beam; 4. Second capping beam; 5. Horizontal bracing; 6. Backfill concrete; 7. New tunnel; 8. Advanced support; 9. Bridge pier (shallow foundation); 10. Bridge pier (pile foundation); 11. Existing bridge. Detailed Implementation
[0029] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.
[0030] like Figure 1-2 The ultra-shallow buried tunnel with minimal clearance passing through the bridge pier shown includes a newly built tunnel 7 and a protective structure. The newly built tunnel 7 is located inside the protective structure. The newly built tunnel 7 is constructed using the tunneling method, eliminating the arch wall anchors. Before excavation, advanced pipe jacking or advanced large pipe shed is constructed.
[0031] like Figure 1-4 As shown, the protective structure includes a first row of isolation piles 1 set along the length of the newly built tunnel 7, a first cap beam 3 rigidly connected to the top of the first row of isolation piles 1, a second row of isolation piles 2 set along the length of the newly built tunnel 7, a second cap beam 4 rigidly connected to the top of the second row of isolation piles 2, and several cross braces 5 set between the first cap beam 3 and the second cap beam 4. One end of the cross brace 5 is rigidly connected to the first cap beam 3, and the other end of the cross brace 5 is rigidly connected to the second cap beam 4.
[0032] The main reinforcement bars of the first row of isolation piles 1 and the second row of isolation piles 2 should extend into the capping beam according to the structural requirements, and then be cast as a whole. The first capping beam 3, the second capping beam 4 and the cross brace 5 are perpendicular and rigidly connected. The main reinforcement bars of the cross brace 5 should extend into the capping beam according to the structural requirements.
[0033] The longitudinal spacing and number of the first row of isolation piles 1 and the second row of isolation piles 2 along the newly built tunnel 7 can be adjusted according to the relative relationship between the newly built tunnel 7 and the structure, the geological conditions of the construction area, the surrounding environment, and the size of the isolation piles.
[0034] The first row of isolation piles 1 and the second row of isolation piles 2 are laterally separated from the outer contour of the newly built tunnel 7 by a distance of 0.5m to 1.0m.
[0035] The first row of isolation piles 1 and the second row of isolation piles 2 should extend into the invert of the newly built tunnel 7 to a depth of not less than 2 meters. When the first row of isolation piles 1 and the second row of isolation piles 2 need to pass through a thick layer of fill, the lower ends of the first row of isolation piles 1 and the second row of isolation piles 2 should be embedded in the bedrock.
[0036] like Figure 1As shown, the area enclosed by the first capping beam 3, the second capping beam 4, and the cross brace 5 is filled with backfill concrete 6, which can enhance the structural rigidity and seal the above-ground structural layer to prevent groundwater infiltration and ensure the safety of the tunnel structure in the later stages. When the surface is uneven, backfill concrete 6 can be used as a cushion layer to fill the gaps between the first capping beam 3, the second capping beam 4, and the ground surface.
[0037] In this embodiment, the first row of isolation piles 1 and the second row of isolation piles 2 are manually excavated piles, and the cross-sectional shape of the first row of isolation piles 1 and the second row of isolation piles 2 is square pile.
[0038] In other embodiments, the first row of isolation piles 1 and the second row of isolation piles 2 are bored piles, and the cross-sectional shape of the first row of isolation piles 1 and the second row of isolation piles 2 is a circular pile.
[0039] When the clearance between the bottom of the main bridge structure and the ground is sufficient, the first row of isolation piles 1 and the second row of isolation piles 2 are prefabricated in the factory and then hoisted into place. When the clearance between the bottom of the main bridge structure and the ground is insufficient to meet the hoisting requirements, the isolation pile reinforcement cages need to be hoisted in sections according to factors such as site clearance and site conditions, and then the isolation piles are cast in place.
[0040] like Figure 2 As shown on the left, when the geological conditions of the construction area are relatively good, bridge piers 9 are generally shallow foundations. For example... Figure 2 As shown on the right, when the geological conditions in the construction area are poor, the piers 10 of the existing bridge 11 are pile foundations, and the first row of isolation piles 1 and the second row of isolation piles 2 extend into the pile foundations of the piers 10 to a depth of not less than 5m.
[0041] Before the construction of the new tunnel 7, settlement and tilt detection points should be set up at relevant locations on the bridge piers and abutments. To ensure the accuracy and timeliness of the monitoring data, automated monitoring is generally adopted.
[0042] During construction, the first row of isolation piles 1, the second row of isolation piles 2, the first capping beam 3, the second capping beam 4, and the cross bracing 5 are excavated and poured as a whole. The isolation piles should extend a certain distance below the bottom of the invert arch of the new tunnel 7 according to the geological conditions and be embedded in the bedrock. After the construction is completed, the structural gaps are filled with backfill concrete 6 to form an inverted U-shaped protective structure with a certain rigidity. Then, the advanced support 8 is constructed to form a reinforcement ring. After that, the new tunnel 7 is excavated and the tunnel lining is constructed.
[0043] The specific embodiments described herein are merely illustrative examples illustrating the spirit of this utility model. Those skilled in the art to which this utility model pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of this utility model or exceeding the scope defined by the appended claims.
Claims
1. A protective structure, characterized in that, It includes a first row of isolation piles, a first cap beam rigidly connected to the top of the first row of isolation piles, a second row of isolation piles, a second cap beam rigidly connected to the top of the second row of isolation piles, and several horizontal braces disposed between the first cap beam and the second cap beam. One end of the horizontal brace is rigidly connected to the first cap beam, and the other end of the horizontal brace is rigidly connected to the second cap beam.
2. The protective structure according to claim 1, characterized in that, The area enclosed by the first crown beam, the second crown beam, and the cross brace is filled with backfill concrete.
3. The protective structure according to claim 1, characterized in that, The first and second rows of isolation piles are manually excavated bored piles, and the cross-sectional shape of the first and second rows of isolation piles is square pile.
4. The protective structure according to claim 1, characterized in that, The first and second rows of isolation piles are bored piles, and the cross-sectional shape of the first and second rows of isolation piles is a circular pile.
5. The protective structure according to claim 1, characterized in that, The first and second rows of isolation piles were prefabricated in the factory.
6. The protective structure according to claim 1, characterized in that, The first and second rows of isolation piles are cast-in-place isolation piles.
7. A shallow-buried tunnel with minimal clearance passing through bridge piers and abutments, characterized in that, It includes a newly constructed tunnel and a protective structure as described in any one of claims 1-6, wherein the newly constructed tunnel is located within the protective structure, the newly constructed tunnel is constructed using the cut-and-cover method, the arch wall anchors are eliminated, and advanced support is constructed before excavation.
8. The ultra-shallow buried tunnel with minimal clearance passing through bridge piers and abutments as described in claim 7, characterized in that, When the piers and abutments of an existing bridge are pile foundations, the depth to which the first row of isolation piles and the second row of isolation piles extend below the pile foundation of the pier and abutment shall not be less than 5m.
9. The ultra-shallow buried tunnel with minimal clearance passing through bridge piers and abutments as described in claim 7, characterized in that, The first and second rows of isolation piles are laterally separated from the outer contour of the newly built tunnel by a distance of 0.5m to 1.0m.
10. The ultra-shallow buried tunnel with minimal clearance passing through bridge piers and abutments according to claim 7, characterized in that, The first and second rows of isolation piles extend into the newly built tunnel under the invert arch to a depth of not less than 2 meters.