High-speed railway underground blind ditch drainage integrated system

Abstract

The comprehensive blind ditch drainage system for underground high-speed railways includes a foundation pit, retaining piles, a graded crushed stone cushion layer, a drainage blind ditch, and a water collection well. The graded crushed stone cushion layer is arranged on the bottom plate of the foundation pit, and the graded crushed stone cushion layer is covered with geotextile; the retaining piles are arranged on both sides of the foundation pit; longitudinal drainage blind ditches are arranged along the entire line of the retaining piles in the bottom plate of the foundation pit, and transverse drainage blind ditches are arranged at a certain interval, and the longitudinal and transverse blind ditches are connected to form a mesh drainage blind ditch; a water collection well is arranged at the confluence of the mesh drainage blind ditch. The utility model forms a water guide panel through geotextile and graded crushed stone cushion layer, introduces groundwater into the mesh drainage blind ditch and finally converges to the water collection well to pump out the leaking water body of the foundation pit, effectively solving the problem of groundwater leakage in the foundation pit.

Description

Technical Field Background Art

[0002] Railways are known as the main arteries of the national economy. The proportion of tunnel projects in railway construction projects is increasing, especially in the past 10 years, passenger dedicated lines and high-speed railways have developed rapidly. The engineering geology and water pattern conditions of the tunnel site have a direct relationship with the construction progress, construction safety, engineering quality and operation safety of the tunnel, among which water is the most important influencing factor. In the construction process, due to the lack of sufficient attention to the waterproofing and drainage construction, some adverse effects often occur, such as the appearance of various cracks or the infiltration of concrete voids into the tunnel, which leads to the various equipment in the tunnel (communication, track, power supply, lighting, etc.) in a humid environment, which is easy to rust, causing electrical equipment failures and "red light belts" to appear, resulting in high-speed train stops, delays and driving safety. Therefore, it is of great significance to ensure the quality of waterproofing and drainage construction of railway tunnel projects.

[0003] After the large-scale excavation of the underground foundation pit of a high-speed railway tunnel, a large amount of precipitation and groundwater gushing out from the foundation pit retaining structure and the bottom of the pit will affect the normal construction. There are four common drainage and decompression methods in foundation pit engineering: (1) drainage through outdoor drainage ditches and precipitation wells; (2) modification of the bottom plate sump, adding diversion pipes to divert groundwater into the sump, and pumping water from the sump; (3) setting up indoor precipitation wells, laying a certain number of drainage pipes in the newly added surface layer of the bottom plate, and pumping groundwater to the outdoors; (4) arranging drainage ditches in the gap between the foundation pit support structure and the outer wall of the basement, and draining into the outdoor sump through blind ditch pipes, and finally draining into the municipal pipe network. Some scholars have studied the blind ditch drainage system. For example, Wang Haigang et al. studied the role of blind ditches in highway drainage protection, comprehensively considering the location and design purpose of the roadbed blind ditch and the slope support blind ditch, and finally achieved the purpose of economy, easy construction, protection and obvious drainage effect. Xue Chen et al. studied a new type of underground structure anti-floating blind ditch drainage integrated system technology, using the grid-shaped blind ditch and side blind ditch of the underground structure bottom plate to connect the groundwater in the foundation soil below the underground structure with the side blind ditch, which greatly saved the project investment and maintenance costs during use. However, the site conditions and construction backgrounds of different projects are different. When the leakage area of ​​the foundation pit is large or the groundwater content is rich, the traditional blind ditch drainage technology can no longer meet the needs. If the full-section grouting and other methods are used to stop water, the project cost will be greatly increased, which is inconsistent with the project progress requirements. In addition, announcement number CN207143981U discloses a three-series water-rich semi-diagenetic sandstone section subway station foundation pit drainage structure. However, the existing technology does not fully lay a certain thickness of graded crushed stone cushion layer on the bottom of the foundation pit, and cover it with geotextile to form a graded crushed stone cushion layer water guide panel, so it cannot solve the problem of groundwater leakage in the foundation pit. Utility Model Content

[0005] The comprehensive underground blind ditch drainage system of a high-speed railway tunnel includes a foundation pit, retaining piles, a graded crushed stone cushion layer, a drainage blind ditch, and a water collection well, and is characterized in that: a graded crushed stone cushion layer is arranged on the bottom plate of the foundation pit, and a geotextile is covered on the graded crushed stone cushion layer; the retaining piles are arranged on both sides of the foundation pit; longitudinal drainage blind ditches are arranged along the entire line of the retaining piles in the bottom plate of the foundation pit, and transverse drainage blind ditches are arranged at a certain interval, and the longitudinal and transverse drainage blind ditches are connected to form a mesh drainage blind ditch; a water collection well is arranged at the confluence of the mesh drainage blind ditches.

[0006] Preferably, the foundation pit bottom plate is paved with a 20 cm thick graded crushed stone cushion layer.

[0007] Preferably: the mesh drainage blind ditch is arranged in a grid pattern along the four sides and the center of the foundation pit, with a horizontal spacing of 10m.

[0008] Preferably, a blind ditch is laid along the longitudinal direction of the foundation pit from both ends to the center with a slope of 2%; the blind ditch is 20 cm deep and 20 cm wide.

[0009] Preferably, three plastic blind tubes with an outer diameter of 60 mm are arranged in the blind ditch, and the filter membrane is wrapped outside the plastic blind tubes.

[0010] Preferably, the blind ditch gaps around the three plastic blind pipes are filled with graded crushed stone.

[0011] Preferably, a variable frequency booster pump, a liquid level control float valve, a greening pipe and a fire-fighting pipe are arranged in the water collection well; and the groundwater in the water collection well is connected with the fire-fighting pipe and the greening pipe through the variable frequency booster pump.

[0012] Beneficial Effects

[0013] A water-guiding panel is formed by geotextile and graded crushed stone cushion layer, which leads groundwater into the mesh drainage blind ditch and finally converges to the collection well to pump out the leaking water in the foundation pit, effectively solving the problem of groundwater leakage in the foundation pit. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 2 This is a cross-sectional diagram of the comprehensive system of underground blind ditch drainage in high-speed railway tunnels;

[0016] Among them, 1 is a retaining pile; 2 is a longitudinal drainage blind ditch; 3 is a transverse drainage blind ditch; 4 is a water collection well; 5 is a graded gravel cushion water guide panel; 6 is a plastic blind pipe. DETAILED DESCRIPTION

[0017] like Figure 1- 2. The underground blind ditch drainage integrated system of high-speed railway includes foundation pit, retaining piles 1, graded crushed stone cushion layer, drainage blind ditch, and water collection well 4. A 20cm thick graded crushed stone cushion layer is laid on the bottom of the foundation pit, and geotextile is covered on it to form a graded crushed stone cushion water guide panel 5 to drain the water at the bottom of the foundation pit; at the same time, a longitudinal drainage blind ditch 2 is laid along the entire line of the retaining piles in the bottom plate of the foundation pit, and a transverse drainage blind ditch 3 is laid at a certain interval. The longitudinal and transverse blind ditches are connected to form a mesh drainage blind ditch to guide the groundwater collected in the drainage panel, and a water collection well is laid in the center of the foundation pit, which is connected to the mesh drainage blind ditch to collect groundwater and then reasonably pump out according to the water volume. Taking into account the construction process and material cost, the mesh drainage blind ditch uses plastic blind pipes as the water guide channel. The material uses a widely used three-dimensional porous material with high compressive strength, high open porosity, and good durability, which is suitable for the site conditions of this foundation pit.

[0018] The mesh drainage blind ditch is arranged in a grid pattern along the periphery and center of the foundation pit, with a horizontal spacing of 10m. The blind ditch is laid along the foundation pit from both ends to the center with a slope of 2%; the blind ditch is 20cm deep and 20cm wide. The center of the blind ditch is 5cm away from the surface of the cast concrete, and the blind ditch is 20cm deep and 20cm wide. Three plastic blind pipes with an outer diameter of 60mm are set in the blind ditch, wrapped with filter membranes. After the blind pipes are constructed, graded crushed stone is used to fill the gaps in the blind ditch.

[0019] Below we briefly describe the construction process of the high-speed railway underground blind ditch drainage comprehensive system.

[0020] (1) Determine pipe location, water collection well location, and trench excavation

[0021] According to the excavation boundary of the high-speed railway tunnel foundation pit, determine the specific location of the blind ditch and the water collection well, and calculate the blind ditch elevation according to the foundation pit bottom elevation. To ensure safety, it is necessary to find out whether there are underground pipelines and underground obstacles at the pipe position and make appropriate adjustments. Dig trenches according to the blind ditch pipe position and control the excavation elevation. The trenches and water collection wells are connected with longitudinal and transverse slopes according to the plan requirements to facilitate water flow.

[0022] (2) Laying filter membrane and placing blind pipes for connection

[0023] Geotextile filter membranes are laid along the pipes and the filter membranes need to be laid in overlapping patterns. Blind pipes are tied in groups of 3 and connected at the seams. After they are firmly fixed, the filter membranes are wrapped and tied with wire. Two adjacent sections of blind pipes need to be connected to prevent gravel or soil from blocking the passage.

[0024] (3) Laying of graded gravel cushion layer for water guide panel

[0025] The whole bottom of the foundation pit is paved with graded gravel, which needs to have good water conductivity, be laid flat horizontally, and be laid continuously at one time. The cushion layer elevation must meet the design requirements of the foundation pit floor, and the bottom must be higher than the top elevation of the blind ditch.

[0026] (4) Screening and backfilling of blind ditch filter material

[0027] The gap between the blind pipe and the trench wall is backfilled with pebbles or crushed stone filter media. The diameter of the filter media must be larger than the aperture of the blind pipe filter. The filter media must meet the grading requirements and screen out particles outside the upper and lower limits of the design specifications. The backfill construction must be completed continuously in one go and ensure that the trench is dense and stable.

[0028] (5) Connect to the water collection well for drainage

[0029] After the blind pipe is laid, it is connected to the collection well along the designed slope. The leakage water blind ditch converges to the central collection well along the longitudinal and transverse slopes within the working section. Water pumps are used to pump out water in a timely manner according to the amount of water.

[0030] A water collection well is set up in the foundation pit, and a variable frequency booster pump is set up in the water collection well. The well-known PLC technology is used to input relevant data, and the frequency converter and pressure transmitter are automatically controlled to adjust the working state of the variable frequency booster pump to stabilize the pressure of the water supply system. In addition, a liquid level control float valve and pipes for greening pipes and fire fighting are set up in the water collection well. The groundwater is connected to the fire fighting and greening pipes through the variable frequency booster pump for greening and fire fighting. When the water collection well liquid level control float valve drops below the control line, the control valve is closed and is no longer used to supplement greening water and fire fighting water. At the same time, the variable frequency booster pump is no longer running, and automatic opening and closing is implemented to ensure the stable operation of the system.

[0031] The present invention develops a comprehensive underground blind ditch drainage system for high-speed railway tunnels. A water-guiding panel is formed by geotextile and graded crushed stone cushion layer, which leads groundwater into a mesh drainage blind ditch and finally converges it into a collection well to pump out the leaking water in the foundation pit. This effectively solves the problem of groundwater leakage in the foundation pit and achieves good results. It has reliable technology, low cost and short construction period. It is an economical and effective groundwater control measure and can provide reference for similar projects.

[0032] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only describe the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the present invention. The scope of protection claimed by the present invention is defined by the attached claims and their equivalents.

Claims

1. The high-speed railway underground blind ditch drainage integrated system includes foundation pit, retaining piles, graded crushed stone cushion, drainage blind ditch and water collection well, and its characteristics are: A graded crushed stone cushion layer is arranged on the foundation pit bottom plate, and a geotextile is covered on the graded crushed stone cushion layer; the retaining piles are arranged on both sides of the foundation pit; longitudinal drainage blind ditches are arranged along the entire line of the retaining piles in the foundation pit bottom plate, and transverse drainage blind ditches are arranged at a certain interval, and the longitudinal and transverse drainage blind ditches are connected to form a mesh drainage blind ditch; a water collection well is arranged at the confluence of the mesh drainage blind ditches.

2. The high-speed railway underground blind ditch drainage integrated system according to claim 1 is characterized by: The foundation pit bottom plate is paved with a 20cm thick graded crushed stone cushion layer.

3. The high-speed railway underground blind ditch drainage integrated system according to claim 1 is characterized by: The mesh drainage blind ditch is arranged in a grid pattern along the four sides and the center of the foundation pit, with a horizontal spacing of 10m.

4. The high-speed railway underground blind ditch drainage integrated system according to claim 1 is characterized by: The foundation pit is paved with blind ditches along the longitudinal direction from both ends to the center with a slope of 2%; the blind ditch is 20 cm deep and 20 cm wide.

5. The high-speed railway underground blind ditch drainage integrated system according to claim 1 is characterized by: Three plastic blind tubes with an outer diameter of 60 mm are arranged in the blind ditch, and the filter membrane is wrapped outside the plastic blind tubes.

6. The high-speed railway underground blind ditch drainage integrated system according to claim 5 is characterized by: The gaps in the blind ditch are filled with graded crushed stone around the three plastic blind pipes.

7. The high-speed railway underground blind ditch drainage integrated system according to claim 1 is characterized by: The water collection well is provided with a variable frequency booster pump, a liquid level control float valve, a greening pipeline and a fire fighting pipeline; the groundwater in the water collection well is connected with the fire fighting pipeline and the greening pipeline through the variable frequency booster pump.

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