Tunnel anti-seepage capillary retardation structure under high-salt underground water condition and construction method thereof

Abstract

The invention belongs to the technical field of underground engineering seepage prevention, and particularly relates to a tunnel seepage prevention capillary blocking structure under the high-salt underground water condition and a construction method of the tunnel seepage prevention capillary blocking structure. According to the technical scheme, the tunnel anti-seepage capillary blocking structure under the high-salt underground water condition comprises a gravel concrete guide and drainage layer, a drainage system and a compact concrete blocking layer, the gravel concrete guide and drainage layer is connected with a tunnel excavation contour layer, and the drainage system is located between the gravel concrete guide and drainage layer and the compact concrete blocking layer; the waterproof-drainage layer is laid on the inner side of the compact concrete blocking layer, and the second lining pouring layer is arranged on the inner side of the waterproof-drainage layer. According to the tunnel anti-seepage capillary blocking structure under the high-salinity underground water condition and the construction method of the tunnel anti-seepage capillary blocking structure, saline water is guided and drained through the gravel concrete guide and drainage layer and the drainage system, meanwhile, salt and water are actively blocked through the capillary action of the compact concrete blocking layer, and cooperation of prevention and drainage is achieved.

Description

Technical Field

[0001] This invention belongs to the field of underground engineering seepage prevention technology, specifically relating to a capillary barrier structure for tunnel seepage prevention under high salinity groundwater conditions and its construction method. Background Technology

[0002] As a key facility for transportation infrastructure, resource storage, and engineering protection, the structural safety and storage stability of underground tunnels highly depend on the seepage prevention system. However, high-salt groundwater contains high concentrations of chloride and sulfate ions, which can erode the tunnel structure and affect its stability. Traditional tunnel seepage prevention structures mainly rely on "blocking" or "passive protection," such as waterproof membranes, waterstops, and high-grade impermeable and waterproof concrete to forcibly block salt water, but the seepage prevention effect is not good. Summary of the Invention

[0003] This invention provides a capillary barrier structure for tunnel seepage prevention under high-salt groundwater conditions and its construction method. The structure uses a crushed stone concrete drainage layer and a drainage system to drain salt water, while simultaneously using the capillary action of a dense concrete barrier layer to actively block salt and water, thus achieving synergistic seepage prevention and drainage.

[0004] The technical solution of the present invention is as follows: A capillary barrier structure for tunnel seepage prevention under high salinity groundwater conditions includes a crushed stone concrete drainage layer, a drainage system, and a dense concrete barrier layer. The crushed stone concrete drainage layer is connected to the tunnel excavation outline layer. The drainage system is located between the crushed stone concrete drainage layer and the dense concrete barrier layer. A waterproofing-drainage layer is laid inside the dense concrete barrier layer, and a secondary lining pouring layer is set inside the waterproofing-drainage layer.

[0005] Furthermore, in the aforementioned capillary barrier structure for tunnel seepage prevention under high-salt groundwater conditions, the crushed stone concrete drainage layer is formed by spraying crushed stone concrete onto the tunnel excavation outline layer, thus creating a drainage layer and lining for high-salt groundwater; the crushed stone concrete uses granite crushed stone with a particle size of 20-40mm, and 2% air-entraining agent and 1% water-reducing agent are added to the crushed stone concrete mix.

[0006] Furthermore, in the aforementioned capillary retardation structure for tunnel seepage prevention under high-salt groundwater conditions, the drainage system consists of a row of perforated HDPE drainage pipes installed on the crushed stone concrete drainage layer.

[0007] Furthermore, in the high-salt groundwater condition tunnel seepage prevention capillary barrier structure, the dense concrete barrier layer is constructed using a model casting method, where dense concrete is cast on the crushed stone concrete drainage layer and the drainage system to form a dense porous structure with a porosity of less than 2%; the dense concrete mix incorporates 3% cement-based penetrating crystallizer and 5% aluminum-rich admixture.

[0008] Furthermore, the tunnel seepage prevention capillary barrier structure under high salinity groundwater conditions includes a drainage layer comprising geotextile, waterproof membrane, and perforated HDPE drainage pipe II. The geotextile and waterproof membrane are laid on a dense concrete barrier layer, and then the perforated HDPE drainage pipe II is installed.

[0009] Furthermore, in the aforementioned capillary retardation structure for tunnel seepage prevention under high-salt groundwater conditions, the secondary lining is formed by casting reinforced concrete on-site using formwork on the drainage layer to create an inner lining structure.

[0010] Furthermore, in the aforementioned capillary retardation structure for tunnel seepage prevention under high-salt groundwater conditions, the lower ends of HDPE drainage pipe one and HDPE drainage pipe two are connected to the transverse drainage pipe.

[0011] Furthermore, in the aforementioned capillary impermeable structure for tunnel seepage prevention under high salinity groundwater conditions, a tunnel floor slab is laid inside the tunnel, and a drainage ditch is provided under the tunnel floor slab. A transverse drainage pipe is connected to the drainage ditch through a drainage channel.

[0012] The construction method for the capillary retardation structure for tunnel seepage prevention under the above-mentioned high-salinity groundwater conditions includes the following steps: 1) After tunnel excavation, the rock wall is treated to remove loose rock blocks and anchor potentially unstable rock blocks, forming the tunnel excavation outline layer; 2) Prepare crushed stone concrete using 20-40mm granite crushed stone, mixed with 2% air-entraining agent and 1% water-reducing agent. After mixing evenly, use a shotcrete machine to spirally spray the crushed stone concrete onto the tunnel excavation outline layer from bottom to top, spraying in layers multiple times, spraying the second layer after each layer has initially set. The spraying thickness is determined according to the surrounding rock grade and specification requirements, forming a crushed stone concrete guide layer. 3) Install a drainage system on the crushed stone concrete drainage layer; the drainage system consists of HDPE drainage pipes distributed along the circumferential and longitudinal directions of the tunnel; the circumferentially distributed HDPE drainage pipes are installed at 5m intervals, and the longitudinally distributed HDPE drainage pipes are installed along the axial direction of the tunnel; the HDPE drainage pipes are wrapped with non-woven fabric to prevent rock debris and other impurities from clogging the pipe holes. 4) Prepare dense concrete by adding 3% cement-based penetrating crystallizer and 5% aluminum-rich admixture to the concrete; construct by casting the formwork, pouring the dense concrete onto the crushed stone concrete drainage layer and drainage system to form a dense porous structure with a porosity of less than 2%, thus obtaining a dense concrete barrier layer; the thickness of the dense concrete barrier layer is the same as that of the crushed stone concrete drainage layer. 5) On the dense concrete barrier layer, first lay geotextile and waterproof board, then install the perforated HDPE drainage pipe II, and wrap the HDPE drainage pipe II with non-woven fabric to form a waterproof layer. 6) On the waterproofing and drainage layer, the inner lining structure is made by casting reinforced concrete on site using formwork, forming the secondary lining layer; 7) Install horizontal drainage pipes, with the lower ends of HDPE drainage pipe one and HDPE drainage pipe two connected to the horizontal drainage pipes. 8) A tunnel floor slab is laid inside the tunnel, and a drainage ditch is provided under the tunnel floor slab. Horizontal drainage pipes are connected to the drainage ditch through drainage channels.

[0013] The beneficial effects of this invention are as follows: 1. This invention is based on the principle of capillary blockage. It consists of a capillary blockage structure composed of "crushed stone concrete drainage layer (coarse-grained medium) - drainage system - dense concrete blockage layer (fine-grained medium)". The crushed stone concrete drainage layer and drainage system drain salt water, while the dense concrete blockage layer actively blocks salt and water through capillary action, thus achieving synergistic prevention and drainage.

[0014] 2. In addition to bearing the structural functions of load-bearing and compressive strength, the crushed stone concrete drainage layer also serves a rapid drainage function. The crushed stone concrete (similar to a coarse-grained medium) enables the rapid drainage of brine. Most of the salt ions are discharged with the groundwater through the crushed stone concrete drainage layer into the HDPE drainage pipe of the drainage system. The drainage system is located between the crushed stone concrete drainage layer and the dense concrete barrier layer. Its main function is to quickly drain the infiltrated high-salt groundwater and prevent water and salt from stagnating. Then, the dense concrete (similar to a fine-grained medium) is cast to slow down and prevent the infiltration of salt ions carried by water. Because the dense concrete has low porosity and small pore size, the small pore size cannot form sufficient surface tension to pull water in, which is equivalent to cutting off the "channel" for the migration of salt water into the tunnel, thus forming a better waterproof barrier.

[0015] 3. The seepage-proof capillary barrier structure of the present invention has the characteristics of "load-bearing capacity, salt corrosion resistance, and easy construction". Attached Figure Description

[0016] Figure 1 This is a schematic diagram of a capillary barrier structure for tunnel seepage prevention under high-salt groundwater conditions. Detailed Implementation

[0017] like Figure 1 As shown, a capillary barrier structure for tunnel seepage prevention under high salinity groundwater conditions includes a crushed stone concrete drainage layer 2, a drainage system 3, and a dense concrete barrier layer 4. The crushed stone concrete drainage layer 2 is connected to the tunnel excavation outline layer 1. The drainage system 3 is located between the crushed stone concrete drainage layer 2 and the dense concrete barrier layer 4. A waterproofing-drainage layer 5 is laid inside the dense concrete barrier layer 4, and a secondary lining casting layer 6 is set inside the waterproofing-drainage layer 5.

[0018] The crushed stone concrete drainage layer 2 is formed by spraying crushed stone concrete onto the tunnel excavation outline layer 1, creating a drainage layer and lining for high-salt groundwater. The crushed stone concrete uses granite crushed stone with a particle size of 20-40mm, and incorporates 2% air-entraining agent and 1% water-reducing agent in its mix proportion. The drainage system 3 consists of a row of perforated HDPE drainage pipes installed on the crushed stone concrete drainage layer 2. The dense concrete retaining layer 4 is formed by casting using a mold casting method, pouring dense concrete onto the crushed stone concrete drainage layer 2 and the drainage system 3, creating a dense porous structure with a porosity of less than 2%. The dense concrete mix incorporates 3% cement-based penetrating crystallizer and 5% alumina-rich admixture.

[0019] The waterproofing-drainage layer 5 includes geotextile, waterproof membrane, and perforated HDPE drainage pipe 2. The geotextile and waterproof membrane are laid on the dense concrete barrier layer 4, and then the perforated HDPE drainage pipe 2 is installed. The secondary lining layer 6 is formed by casting reinforced concrete on the waterproofing-drainage layer 5 using formwork to form the inner lining structure. The lower ends of HDPE drainage pipe 1 and HDPE drainage pipe 2 are connected to the transverse drainage pipe 8. A tunnel floor slab 7 is laid inside the tunnel, and a drainage ditch is provided under the tunnel floor slab 7. The transverse drainage pipe 8 is connected to the drainage ditch through a drainage channel 9.

[0020] The construction method for the capillary retardation structure for tunnel seepage prevention under the above-mentioned high-salinity groundwater conditions includes the following steps: 1) After the tunnel is excavated, the rock wall is treated to remove loose rock blocks and anchor potentially unstable rock blocks, forming the tunnel excavation outline layer 1; 2) Prepare crushed stone concrete using 20-40mm granite crushed stone, mixed with 2% air-entraining agent and 1% water-reducing agent. After mixing evenly, use a spraying machine to spirally spray the crushed stone concrete onto the tunnel excavation outline layer 1 from bottom to top, spraying in layers multiple times, spraying the second layer after each layer has initially set. The spraying thickness is determined according to the surrounding rock grade and specification requirements, forming the crushed stone concrete drainage layer 2. The crushed stone concrete drainage layer 2 serves as a lining to bear load, and on the other hand, the large pore size of the crushed stone concrete enables rapid drainage of brine, allowing most salt ions to flow with the water flow, thus achieving the effect of salt removal. 3) Install drainage system 3 on crushed stone concrete drainage layer 2; drainage system 3 consists of HDPE drainage pipes distributed along the circumferential and longitudinal directions of the tunnel; the circumferentially distributed HDPE drainage pipes are installed at 5m intervals, and the longitudinally distributed HDPE drainage pipes are installed along the axial direction of the tunnel; the HDPE drainage pipes are wrapped with non-woven fabric to prevent rock debris and other impurities from clogging the pipe holes; the main function of drainage system 3 is to drain the salt ions and water that seep into the crushed stone concrete, quickly drain the infiltrated high-salt groundwater, and prevent water and salt from stagnating. 4) Prepare dense concrete by adding 3% cement-based penetrating crystallizer and 5% aluminum-rich admixture to the concrete; construct by casting the formwork, pouring the dense concrete onto the crushed stone concrete drainage layer 2 and drainage system 3 to form a dense porous structure with a porosity of less than 2%, thus obtaining a dense concrete barrier layer 4; the dense concrete barrier layer 4 has the same thickness as the crushed stone concrete drainage layer 2; the dense concrete barrier layer 4 forms a physical barrier by blocking and delaying the penetration of salt ions carried by water through strong capillary force, thereby achieving the effect of salt blocking and slowing down and preventing the penetration of salt ions carried by water. 5) On the dense concrete barrier layer 4, first lay geotextile and waterproof board, then install the perforated HDPE drainage pipe 2. The HDPE drainage pipe 2 is wrapped with non-woven fabric to form a waterproof layer 5, which realizes the discharge and barrier of the remaining small amount of salt water. 6) On the waterproofing and drainage layer 5, the inner lining structure is made by casting reinforced concrete on site using formwork, forming the secondary lining layer 6. 7) Install the horizontal drainage pipe 8, and connect the lower ends of HDPE drainage pipe 1 and HDPE drainage pipe 2 to the horizontal drainage pipe 8. 8) A tunnel floor slab 7 is laid inside the tunnel. A drainage ditch is provided under the tunnel floor slab 7. A transverse drainage pipe 8 is connected to the drainage ditch through a drainage channel 9. Water discharged from HDPE drainage pipe 1 and HDPE drainage pipe 2 flows into the drainage channel 9 through the transverse drainage pipe 8 and is finally discharged into the drainage ditch.

[0021] The above embodiments are merely preferred embodiments of the present invention, and the scope of protection of the present invention is not limited thereto. Any simple changes or equivalent substitutions of the technical solutions that can be obviously obtained by those skilled in the art within the scope of the technology disclosed in the present invention shall fall within the scope of protection of the present invention.

Claims

1. A capillary impediment structure for tunnel seepage prevention under high-salinity groundwater conditions, characterized in that, It includes a crushed stone concrete drainage layer, a drainage system, and a dense concrete barrier layer. The crushed stone concrete drainage layer is connected to the tunnel excavation outline layer. The drainage system is located between the crushed stone concrete drainage layer and the dense concrete barrier layer. A waterproof and drainage layer is laid inside the dense concrete barrier layer, and a secondary lining pouring layer is set inside the waterproof and drainage layer.

2. The capillary impediment structure for tunnel seepage prevention under high-salinity groundwater conditions according to claim 1, characterized in that, The crushed stone concrete drainage layer is formed by spraying crushed stone concrete onto the tunnel excavation outline layer to form a drainage layer and lining for high-salt groundwater. The crushed stone concrete uses granite crushed stone with a particle size of 20-40mm, and 2% air-entraining agent and 1% water-reducing agent are added to the crushed stone concrete mix.

3. The capillary impediment structure for tunnel seepage prevention under high-salinity groundwater conditions according to claim 1, characterized in that, The drainage system consists of a row of perforated HDPE drainage pipes installed on the crushed stone concrete drainage layer.

4. The capillary impediment structure for tunnel seepage prevention under high-salinity groundwater conditions according to claim 1, characterized in that, The dense concrete barrier layer is constructed using a mold casting method, whereby dense concrete is poured onto the crushed stone concrete drainage layer and the drainage system to form a dense porous structure with a porosity of less than 2%. The dense concrete mix incorporates 3% cement-based penetrating crystallizer and 5% aluminum-rich admixture.

5. The capillary impediment structure for tunnel seepage prevention under high-salinity groundwater conditions according to claim 3, characterized in that, The waterproofing layer consists of geotextile, waterproof membrane, and perforated HDPE drainage pipes. The geotextile and waterproof membrane are laid on a dense concrete barrier layer, and then the perforated HDPE drainage pipes are installed.

6. The capillary retardation structure for tunnel seepage prevention under high-salinity groundwater conditions according to claim 1, characterized in that, The secondary lining layer is formed by casting reinforced concrete on-site using formwork on the waterproofing and drainage layer to create the inner lining structure.

7. The capillary impediment structure for tunnel seepage prevention under high-salinity groundwater conditions according to claim 5, characterized in that, The lower ends of HDPE drainage pipe one and HDPE drainage pipe two are connected to the horizontal drainage pipe.

8. The capillary impediment structure for tunnel seepage prevention under high-salinity groundwater conditions according to claim 7, characterized in that, The tunnel floor is laid inside the tunnel, and drainage ditches are installed under the tunnel floor. Horizontal drainage pipes are connected to the drainage ditches through drainage channels.

9. The construction method of the capillary retardation structure for tunnel seepage prevention under high-salinity groundwater conditions as described in any one of claims 1-8, characterized in that, Includes the following steps: 1) After tunnel excavation, the rock wall is treated to remove loose rock blocks and anchor potentially unstable rock blocks, forming the tunnel excavation outline layer; 2) Prepare crushed stone concrete using 20-40mm granite crushed stone, mixed with 2% air-entraining agent and 1% water-reducing agent. After mixing evenly, use a shotcrete machine to spirally spray the crushed stone concrete onto the tunnel excavation outline layer from bottom to top, spraying in layers multiple times, spraying the second layer after each layer has initially set. The spraying thickness is determined according to the surrounding rock grade and specification requirements, forming a crushed stone concrete guide layer. 3) Install a drainage system on the crushed stone concrete drainage layer; the drainage system consists of HDPE drainage pipes distributed along the circumferential and longitudinal directions of the tunnel; the circumferentially distributed HDPE drainage pipes are installed at 5m intervals, and the longitudinally distributed HDPE drainage pipes are installed along the axial direction of the tunnel; the HDPE drainage pipes are wrapped with non-woven fabric to prevent rock debris and other impurities from clogging the pipe holes. 4) Prepare dense concrete by adding 3% cement-based penetrating crystallizer and 5% aluminum-rich admixture to the concrete; construct by casting the formwork, pouring the dense concrete onto the crushed stone concrete drainage layer and drainage system to form a dense porous structure with a porosity of less than 2%, thus obtaining a dense concrete barrier layer; the thickness of the dense concrete barrier layer is the same as that of the crushed stone concrete drainage layer. 5) On the dense concrete barrier layer, first lay geotextile and waterproof board, then install the perforated HDPE drainage pipe II, and wrap the HDPE drainage pipe II with non-woven fabric to form a waterproof layer. 6) On the waterproofing and drainage layer, the inner lining structure is made by casting reinforced concrete on site using formwork, forming the secondary lining layer; 7) Install horizontal drainage pipes, with the lower ends of HDPE drainage pipe one and HDPE drainage pipe two connected to the horizontal drainage pipes. 8) A tunnel floor slab is laid inside the tunnel, and a drainage ditch is provided under the tunnel floor slab. Horizontal drainage pipes are connected to the drainage ditch through drainage channels.

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