An integrated waterproofing and drainage and buffer backfill system and construction method for a tunnel and open cut
Patent Information
- Application Number
- CN202610864332.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-06-16
- Publication Date
- 2026-09-01
AI Technical Summary
该方法功能单一，主要目的是恢复地形地貌
1.防排水效能根本性提升：通过下排上隔的双重机制（下层碎石主动导排水，上层粘土主动阻隔水），有效消除了拱背积水隐患，极大减轻了主体结构防水层的静水压力，从根源上保障了衬砌不渗漏。经工程验证，采用此法后，明洞衬砌背后渗漏率可降低95%以上。
Smart Images
Figure CN122669741A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of tunnel engineering technology, and more specifically, to an integrated drainage and buffer backfilling system and construction method for open-cut tunnels. Background Technology
[0002] Traditional tunnels, whether open or enclosed, typically use simple plain soil or gravel backfilling, or multiple layers of backfilling, primarily to restore the terrain.
[0003] Conventional plain soil and gravel backfilling method: This method involves directly excavating earth and rock or purchasing soil and rock materials for one-time or layered backfilling to the design elevation, followed by surface leveling. This method has a single function, primarily aimed at restoring the topography. Its core drawbacks are: ineffective drainage of potential groundwater behind the structure, easily leading to water accumulation in the arch back, and long-term hydrostatic pressure threatening the waterproofing layer of the main structure; the backfill is loose, with poor scouring and shear resistance, failing to effectively buffer impact loads such as falling rocks; and subsequent vegetation restoration is prone to damage due to soil erosion and settlement.
[0004] Simple layered backfilling method: This method simply distinguishes between large and small particle sizes during backfilling, for example, filling the bottom layer with crushed stone and the top layer with soil. Although this method considers drainage to some extent, it has serious systemic shortcomings: it lacks an effective waterproof layer, allowing surface water to easily infiltrate; it lacks clear technical indicators (such as thickness, compaction degree, and material specifications) and coordinated design between functional layers; and it lacks an integral rigid protective layer, making it prone to interlayer mixing and functional failure under long-term use and hydrological effects.
[0005] In summary, both of the above methods have obvious drawbacks: Weak waterproofing and drainage: The permeability of ordinary backfill soil is uneven, which can easily lead to water accumulation at the top of the structure. Long-term water pressure may penetrate the waterproof layer, causing leakage in the lining ("arch back water accumulation effect").
[0006] Poor impact resistance and buffering capacity: For impact loads such as rockfalls and debris flows, the loose backfill soil has limited buffering and energy dissipation effect, and the impact force can be directly transmitted to the open tunnel structure below, causing damage.
[0007] The structural protection and ecological restoration are disconnected: If soil is directly covered with greenery after backfilling, plant roots and rainwater infiltration may damage the stability of the backfill and the waterproof layer. If hardening treatment is performed, it will be detrimental to ecological restoration.
[0008] Based on the above factors, it is necessary to improve the backfilling scheme for open-cut tunnels to create a systematic solution that integrates drainage, buffering, water isolation, rigid protection, and ecological matrix in an orderly manner and achieves functional synergy. Summary of the Invention
[0009] The purpose of this invention is to address the shortcomings of existing technologies by providing an integrated drainage and buffer backfill system and construction method for open-cut tunnels that can systematically integrate and synergize drainage, buffering, waterproofing, rigid protection, and ecological matrix functions.
[0010] To achieve the above objectives, the technical solution adopted by this invention is: an integrated waterproofing and buffer backfilling system for open-cut tunnels, integrally installed on the waterproof layer of the tunnel lining arch, comprising: A cast-in-place coarse-grained subbase is placed on top of the waterproof layer, serving as the base layer and leveling layer; The crushed stone drainage layer is set on top of the cast-in-place coarse-grained cushion layer to form a horizontal drainage channel; A clay waterproof layer is placed on top of a gravel drainage layer to serve as a waterproof barrier. The soil-rock buffer layer is set on top of the clay waterproof layer to absorb and buffer impacts or loads from above. The concrete protective layer is placed on top of the soil and rock buffer layer to seal and fix the underlying layers. The soil-covered greening layer is set on top of the concrete protective layer and is used for planting vegetation.
[0011] Preferably, the cast-in-place coarse-grained cushion layer is a graded crushed stone casting layer or a pebble casting layer.
[0012] Preferably, a drainage pipe is pre-embedded in the crushed stone drainage layer, and the drainage pipe is connected to the tunnel side ditch or the central drainage ditch of the tunnel.
[0013] Preferably, the clay in the clay waterproofing layer is compacted clay.
[0014] Preferably, the material of the soil-rock buffer layer is a layered soil-rock mixture.
[0015] Preferably, the concrete grade of the concrete protective layer is C20 fine aggregate concrete.
[0016] Preferably, the thickness of the clay waterproof layer is ≥50cm and the compaction degree is ≥93%.
[0017] Preferably, the thickness of the concrete protective layer is ≥7cm.
[0018] A construction method for an integrated waterproofing, drainage, and buffer backfilling system for tunnel openings is also provided, comprising the following steps: S1. Surface preparation and subbase construction: Clean the arch back base surface, pour or lay a cast-in-place coarse-grained cushion layer composed of low-grade concrete or graded crushed stone to level the base surface, protect the waterproof layer, and provide a stable foundation for the upper layer construction. S2. Construction of the active drainage subsystem: On top of the subbase, clean, graded crushed stone of the designed thickness is laid to form a crushed stone drainage layer; The key points of construction are: a) while laying crushed stone, pre-embed longitudinal drainage pipes according to the designed longitudinal slope; b) the drainage pipes must be reliably connected to the tunnel side ditch or central drainage ditch to ensure unobstructed drainage path; c) the crushed stone layer should be laid flat to form an effective horizontal water guiding channel. S3. Construction of the active waterproofing subsystem: On top of the crushed stone drainage layer, a low-permeability clay layer of designed thickness is laid to form a clay waterproof layer. The core control index for construction is compaction. Small road rollers or electric rammers are used for layered compaction. The loose thickness of each layer is no more than 30cm. After each layer is compacted, the compaction degree is tested on site until the compaction degree of the entire line is ≥93%, which is used as a key barrier to prevent surface water infiltration. S4. Construction of the passive buffer subsystem: On top of the clay waterproof layer, backfill with soil and rock mixture to form a soil and rock buffer layer. Backfilling should be carried out in layers, with each layer controlled at 40-50cm in thickness, and compacted using equipment. Its compaction degree is slightly lower than that of the waterproof layer. This layer mainly uses the porosity and deformation of the material itself to absorb and disperse external impact energy. S5. Construction of Rigid Protection and Ecological Subbed Subsystem: A layer of C20 fine stone concrete is poured on the top surface of the buffer layer to form a rigid protective layer. Construction technical requirements: a) The thickness is not less than 7cm; b) Compartment joints are required to prevent cracking; c) The concrete should be vibrated and compacted, and the surface should be smoothed. It is used to seal and fix the functional layers below, prevent erosion and human damage, and provide an absolutely stable and non-settling solid base for subsequent greening. S6. Construction of the ecological restoration layer: After the concrete protective layer reaches its strength, planting soil is placed on top to form a greening layer, and ecological restoration is carried out.
[0019] This invention has outstanding substantive features and significant progress compared to the prior art. Specifically, this invention has the following advantages: 1. Fundamentally improved drainage efficiency: Through a dual mechanism of bottom drainage and top isolation (the lower layer of crushed stone actively guides drainage, while the upper layer of clay actively blocks water), the potential for water accumulation on the arch back is effectively eliminated, greatly reducing the hydrostatic pressure on the main structure's waterproof layer and ensuring that the lining does not leak from the source. Engineering verification has shown that this method can reduce the leakage rate behind the lining of open-cut tunnels by more than 95%.
[0020] 2. By constructing a composite structural layer that combines flexible buffering with rigid sealing, the backfill material completed by the system can effectively resist the impact of small to medium-sized falling rocks and rainwater erosion. The construction of the concrete protective layer ensures the structural integrity of the entire system during long-term use, solving the problem that traditional backfill materials are easily eroded and hollowed out.
[0021] 3. It achieves an organic combination of engineering protection and ecological restoration: The rigid concrete protective layer provides a stable and non-settling base for greening, avoiding the contradiction between greening and engineering competing for land and interfering with each other, and achieving the engineering target of stabilizing the slope first and then greening the slope.
[0022] 4. Standardized construction and controllable quality: The materials, thickness, and compaction degree of each layer have clear quantitative indicators (e.g., the clay waterproof layer is 50cm thick and the compaction degree is ≥93%; the protective layer is 7cm thick C20 fine stone concrete), which is easy to control and inspect during construction and ensures the reliability of the system function. Attached Figure Description
[0023] Figure 1 This is a schematic diagram of the overall structure of the integrated waterproofing, drainage and buffer backfilling system for open tunnel sections in this invention.
[0024] In the diagram: 1. Tunnel opening; 2. Opening lining; 3. Waterproof layer; 4. Cast-in-place coarse-grained cushion layer; 5. Crushed stone drainage layer; 6. Clay waterproof layer; 7. Soil-rock buffer layer; 8. Concrete protective layer; 9. Soil-covered greening layer. Detailed Implementation
[0025] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In the description of the present invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In the description of the present invention, it should be noted that unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention through specific circumstances. Example 1
[0026] like Figure 1 As shown, an integrated waterproofing, drainage, and buffer backfilling system for open-cut tunnels is integrally installed on the waterproof layer 3 of the arch back of the open-cut lining 2 of the open-cut tunnel 1, comprising: The cast-in-place coarse-grained subbase 4 is placed on top of the waterproof layer and is formed by pouring graded crushed stone or pebbles, serving as the bottom layer and leveling layer of the system.
[0027] The crushed stone drainage layer 5 is set on the cast-in-place coarse-grained cushion layer to form a horizontal drainage channel. Specifically, in this embodiment, it is laid with clean crushed stone to form the main horizontal drainage channel, which can quickly guide water that may seep through the upper layer or water behind the lining to the longitudinal drainage pipe.
[0028] The clay waterproof layer 6 is set on top of the gravel drainage layer and serves as a water barrier. Specifically, in this embodiment, it is made of compacted clay and is located on top of the gravel drainage layer. It serves as a key water barrier to prevent surface water from seeping into the lower drainage layer and the open-cut structure.
[0029] The soil and rock buffer layer 7 is set on top of the clay waterproof layer to absorb and buffer the impact or load from above. In this embodiment, it is made of compacted clay and serves as a key waterproof barrier to prevent surface water from seeping into the lower drainage layer and the open-cut structure.
[0030] The concrete protective layer 8 is set on top of the soil and rock buffer layer to seal and fix the layers below. In this embodiment, the concrete grade used is C20 fine stone concrete, which is a continuous monolithic rigid slab used to seal and fix the layers below, prevent soil erosion and damage by people and animals, and provide a solid base for subsequent greening.
[0031] The soil-covered greening layer 9 is set on top of the concrete protective layer and is completed through soil covering construction. It is used for planting vegetation and carrying out ecological restoration.
[0032] To improve drainage performance, in the preferred embodiment, a longitudinal drainage pipe (such as a Φ100 PVC pipe) is pre-embedded in the gravel drainage layer. This drainage pipe is connected to the tunnel side ditch or central drainage ditch to achieve organized drainage.
[0033] The system comprises several subsystems: a gravel drainage layer combined with longitudinal drainage pipes to form an active drainage subsystem that actively collects and removes water; a clay impermeable layer to form an active impermeable subsystem that reduces infiltration at the source; a soil-rock buffer layer to form a passive buffer subsystem that dissipates energy through material deformation; a concrete protective layer to form a rigid protection subsystem that ensures the long-term stability of each functional layer; and a soil-covered greening layer for ecological restoration. Example 2
[0034] A construction method for an integrated waterproofing, drainage, and buffer backfilling system for tunnel openings, comprising the following steps: S1. Surface preparation and subbase construction: Clean the arch back base surface and pour or lay a cast-in-place coarse-grained cushion layer, which is composed of low-grade concrete or graded crushed stone, to level the base surface, protect the waterproof layer, and provide a stable foundation for the upper layer construction.
[0035] S2. Construction of the active drainage subsystem: On top of the subbase, a layer of clean, graded crushed stone of the designed thickness is laid to form a crushed stone drainage layer. The key points of construction are: a) while laying the crushed stone, longitudinal drainage pipes (such as Φ100 PVC pipes) are pre-embedded according to the designed longitudinal slope; b) the drainage pipes must be reliably connected to the tunnel side ditch or central drainage ditch to ensure unobstructed drainage path; c) the crushed stone layer should be laid flat to form an effective horizontal water guiding channel.
[0036] S3. Construction of the active waterproofing subsystem: Above the gravel drainage layer, a layer of low-permeability clay of the designed thickness (e.g., 50cm) is laid to form a clay impermeable layer. The core control indicator for construction is compaction. It must be compacted in layers (each layer loosely laid no more than 30cm thick) using a small roller or electric rammer. The compaction degree must be tested on-site after each layer is compacted until the overall compaction degree is ≥93% (according to heavy compaction standards). This layer is a crucial barrier preventing surface water infiltration.
[0037] S4. Construction of the passive buffer subsystem: On top of the clay impermeable layer, a soil-rock mixture is backfilled to form a soil-rock buffer layer. Backfilling should be done in layers, with each layer controlled to a thickness of 40-50cm, and compacted using equipment. The compaction degree can be slightly lower than that of the impermeable layer, but overall stability must be ensured. This layer mainly utilizes the porosity and deformation of the material itself to absorb and disperse external impact energy.
[0038] S5. Construction of Rigid Protection and Ecological Subbed Subsystem: This is the final structural step: pouring a layer of C20 fine aggregate concrete on top of the buffer layer to form a rigid protective layer. Construction requirements: a) Thickness not less than 7cm; b) Compartment joints must be provided to prevent cracking; c) The concrete should be vibrated to ensure compaction and the surface should be smooth. The purpose of this layer is to seal and fix the functional layers below, preventing erosion and human damage, and providing an absolutely stable and non-settling solid foundation for subsequent greening.
[0039] S6. Construction of the ecological restoration layer: After the concrete protective layer reaches its strength, planting soil is covered on top to form a soil-covered green layer, and ecological restoration is carried out by methods such as topsoil spraying, grass pavers, or planting shrubs.
[0040] This scheme was experimentally verified in the open-cut section of the Yalong River Kayang Highway Tunnel. The specific operation process is as follows: On the arch lining of the open-cut tunnel, where construction and the outer waterproofing layer have been completed, a cast-in-place coarse-grained cushion layer is first poured to level the base surface. Then, a crushed stone drainage layer is laid, with longitudinal PVC drainage pipes pre-embedded during installation to ensure a smooth slope and connection to the main drainage system. A clay waterproofing layer is then laid on top of the crushed stone layer and compacted in layers using small compaction machinery to the designed thickness (50cm) and compaction degree (≥93%).
[0041] Next, the soil-rock buffer layer is backfilled and compacted. After all backfill layers are completed and pass inspection, a 7cm thick layer of C20 fine aggregate concrete is poured on top, compacted by vibration, and then smoothed and cured. Once the concrete reaches its design strength, soil is covered on top, and vegetation is restored by methods such as hydroseeding or planting shrubs.
[0042] The solution successfully achieved a comprehensive effect of zero water accumulation and erosion on the tunnel roof, as well as good greening, verifying the rationality and effectiveness of its design.
[0043] Finally, it should be noted that: the preferred embodiments of this patent have been described in detail above, but this patent is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this patent.
Claims
1. An integrated waterproofing, drainage, and buffer backfilling system for open-cut tunnels, integrally installed on the waterproof layer of the tunnel lining arch, characterized in that: include: A cast-in-place coarse-grained subbase is placed on top of the waterproof layer, serving as the base layer and leveling layer; The crushed stone drainage layer is set on top of the cast-in-place coarse-grained cushion layer to form a horizontal drainage channel; A clay waterproof layer is placed on top of a gravel drainage layer to serve as a waterproof barrier. The soil-rock buffer layer is set on top of the clay waterproof layer to absorb and buffer impacts or loads from above. The concrete protective layer is placed on top of the soil and rock buffer layer to seal and fix the underlying layers. The soil-covered greening layer is set on top of the concrete protective layer and is used for planting vegetation.
2. The integrated drainage and buffer backfill system for open-cut tunnels according to claim 1, characterized in that: The cast-in-place coarse-grained cushion layer is a graded crushed stone casting layer or a pebble casting layer.
3. The integrated drainage and buffer backfill system for open-cut tunnels according to claim 1, characterized in that: A drainage pipe is pre-embedded in the crushed stone drainage layer, and the drainage pipe is connected to the tunnel side ditch or the central drainage ditch of the tunnel.
4. The integrated drainage and buffer backfill system for open-cut tunnels according to claim 1, characterized in that: The clay in the clay waterproofing layer is compacted clay.
5. The integrated drainage and buffer backfill system for open-cut tunnels according to claim 1, characterized in that: The material of the soil and rock buffer layer is a layered soil and rock mixture.
6. The integrated drainage and buffer backfill system for open-cut tunnels according to claim 1, characterized in that: The concrete grade of the concrete protective layer is C20 fine aggregate concrete.
7. The integrated drainage and buffer backfill system for open-cut tunnels according to claim 1, characterized in that: The thickness of the clay waterproof layer is ≥50cm, and the compaction degree is ≥93%.
8. The integrated drainage and buffer backfill system for open-cut tunnels according to claim 1, characterized in that: The thickness of the concrete protective layer is ≥7cm.
9. A construction method for an integrated drainage and buffer backfill system for open-cut tunnels, characterized in that, The integrated drainage and buffer backfill system for tunnel openings as described in any one of claims 1-8 includes the following steps: S1. Surface preparation and subbase construction: Clean the arch back base surface, pour or lay a cast-in-place coarse-grained cushion layer composed of low-grade concrete or graded crushed stone to level the base surface, protect the waterproof layer, and provide a stable foundation for the upper layer construction. S2. Construction of the active drainage subsystem: On top of the subbase, clean, graded crushed stone of the designed thickness is laid to form a crushed stone drainage layer; The key points of construction are: a) while laying crushed stone, pre-embed longitudinal drainage pipes according to the designed longitudinal slope; b) the drainage pipes must be reliably connected to the tunnel side ditch or central drainage ditch to ensure unobstructed drainage path; c) the crushed stone layer should be laid flat to form an effective horizontal water guiding channel. S3. Construction of the active waterproofing subsystem: On top of the crushed stone drainage layer, a low-permeability clay layer of designed thickness is laid to form a clay waterproof layer. The core control index for construction is compaction. Small road rollers or electric rammers are used for layered compaction. The loose thickness of each layer is no more than 30cm. After each layer is compacted, the compaction degree is tested on site until the compaction degree of the entire line is ≥93%, which is used as a key barrier to prevent surface water infiltration. S4. Construction of the passive buffer subsystem: On top of the clay waterproof layer, backfill with soil and rock mixture to form a soil and rock buffer layer. Backfilling should be carried out in layers, with each layer controlled at 40-50cm in thickness, and compacted using equipment. Its compaction degree is slightly lower than that of the waterproof layer. This layer mainly uses the porosity and deformation of the material itself to absorb and disperse external impact energy. S5. Construction of Rigid Protection and Ecological Subbed Subsystem: A layer of C20 fine stone concrete is poured on the top surface of the buffer layer to form a rigid protective layer. Construction technical requirements: a) The thickness is not less than 7cm; b) Compartment joints are required to prevent cracking; c) The concrete should be vibrated and compacted, and the surface should be smoothed. It is used to seal and fix the functional layers below, prevent erosion and human damage, and provide an absolutely stable and non-settling solid base for subsequent greening. S6. Construction of the ecological restoration layer: After the concrete protective layer reaches its strength, planting soil is placed on top to form a greening layer, and ecological restoration is carried out.