An integrated well structure and construction method for bottom water intake and top water recharging

Abstract

The present invention discloses an integrated well structure and construction method for bottom water intake and top recharging. In order to lower the water level in the foundation pit, a method of pipe well dewatering + peripheral supplementary recharging wells is adopted to solve the phenomenon of soil consolidation and sinking. In order to effectively solve the problem of the working surface of the construction site, a well wall structure is invented, that is, bottom water intake and top recharging, which effectively releases the water head pressure at the bottom of the foundation pit and reduces the sudden surge phenomenon at the bottom of the pit. At the same time, it can reduce the damage to the side wall retaining structure of the foundation pit caused by the bypass of water bodies, clarify the buried depth of the aquifer, carry out construction dewatering in a targeted manner, reduce the exploitation of groundwater resources, and reflect the saving of electricity and water resources from the green and environmentally friendly construction, reduce the cracking of surrounding buildings, ground subsidence, and underground pipeline rupture caused by the consolidation of the stratum caused by precipitation, effectively reduce the construction working surface, reduce the mutual interference between different processes, and save the space working surface.

Description

Technical Field

[0001] The invention relates to the technical field of well structures, and in particular to an integrated well structure for taking water from a lower part and recharging water from an upper part, and a construction method thereof. Background Art

[0002] In foundation pit dewatering projects where the geological conditions are an upper clay layer, an underconsolidated silt layer, and a water-rich gravel layer at the bottom, the traditional method of groundwater control is to use tube well dewatering.

[0003] A reinjection well structure described in announcement number CN117230864A includes a reinjection well, a well pipe, a water stop ring and a reinjection pipeline assembly; the well pipe is coaxially arranged in the reinjection well, and a filler is filled between the outer wall of the well pipe and the inner wall of the reinjection well; the well pipe includes a sedimentation pipe section, a filtration pipe section and a solid pipe section connected in sequence from bottom to top, and the water stop ring is arranged on the outer wall surface of the solid pipe section; the reinjection pipeline assembly includes a reinjection pipeline, the upper end of which is located at the upper part of the reinjection well and is connected to an external water source, and the lower end of the reinjection pipeline extends into the filtration pipe section of the well pipe. The present invention also provides a reinjection construction method. The beneficial effects of the present invention are: the present invention increases the seepage path of groundwater by arranging a water stop ring in the well pipe section, and at the same time adopts a secondary grouting process to seal the upper backfill layer, effectively ensuring the maximum reinjection pressure allowed by the reinjection well structure, and adopts pressurized reinjection measures to raise the water level in the high-head confined aquifer area.

[0004] Announcement No. CN116180711A discloses a foundation pit construction recharge well structure, which belongs to the field of building construction technology, including a recharge well body, and a plurality of groups of openings are opened on the well wall of the recharge well body along the extension direction of the recharge well body. A water injection core pipe for water injection is arranged on the inner side of the recharge well body, and the water injection core pipe goes deep into the recharge well body, the lower end of the water injection core pipe is closed, and the upper end of the water injection core pipe is connected to a hydraulic loading device; two groups of movable sealing components are fixed at intervals at the lower part of the water injection core pipe, and the movable sealing components can expand after the water injection core pipe reaches the specified position, thereby sealing the gap between the water injection core pipe and the inner wall of the recharge well body, and a water injection hole is opened on the water injection core pipe between the two groups of movable sealing components. The recharge well of the present invention can be recharged for strata at different depths to meet the construction needs on site, greatly shortening the construction period and saving costs.

[0005] Therefore, the current recharge well structure still has the following disadvantages.

[0006] Simple pipe well dewatering is prone to cause the surrounding buildings to sink and tilt, roads to crack, and pipelines to break. Then it is necessary to consider setting up a recharge well at the construction site. The construction surface of the recharge well naturally occupies the construction site, and it is also inevitable to interfere with each other's operations. In addition, the traditional gravel backfill outside the well wall is generally made of large-grained permeable material, and the upper part is made of impermeable and breathable material. Summary of the invention

[0007] In view of the above-mentioned deficiencies in the existing process methods and equipment, this patent invents an integrated well structure and construction method for bottom water intake and top recharging, the purpose of which is to lower the water level in the foundation pit, and adopt the method of pipe well dewatering + peripheral supplementary recharging wells to solve the phenomenon of soil consolidation and sinking. In order to effectively solve the problem of the working surface at the construction site, a well wall structure is now invented, that is, bottom water intake and top recharging.

[0008] In order to solve the above technical problems, the technical solution provided by the present invention is: an integrated well structure with water intake at the bottom and recharge at the top, including a dewatering well core pipe, an outer lining pipe, a water outlet pipe, and a supply return pipe. A pumping device is arranged in the dewatering well core pipe to discharge the water in the aquifer through the water outlet pipe to a designated location. The dewatering well core pipe is composed of an upper non-hole well wall pipe, a partition well wall in the middle, and a leaky well wall pipe at the bottom. The length of the leaky well wall pipe is greater than the thickness of the aquifer, and the leaky well wall pipe is connected to the upper non-hole well wall pipe.

[0009] The outer liner is a cylindrical structure, the lower part of which is closely connected to the core pipe of the drainage well. The length of the outer liner is shorter than that of the core pipe of the drainage well. The upper part of the outer liner is a reinjection flower pipe, and the lower part is composed of a middle septum wall. The length of the upper reinjection flower pipe is greater than the depth of the impermeable layer A. The lower part is the middle septum wall, which is a closed well chamber composed of upper, lower, left and right wall panels, and its strength can withstand the impact of water flow; the middle septum wall has a moderate length and its main function is to cut off the hydraulic connection between the upper reinjection water body and the lower aquifer water body to prevent the formation of a passage; the reinjection flower pipe wall is a flower pipe, and its flower hole is the same size as the flower hole of the leak-type well wall pipe; the middle septum wall is made of impermeable material, that is, no flower holes are punched;

[0010] The supply return pipe is connected to the outlet pipe. The diameter of the supply return pipe is smaller than that of the outlet pipe. The pipe wall is positioned deep into the recharging flower pipe and its length is 1 / 2 of the length of the recharging flower pipe. A valve is arranged on the upper part of the pipe wall.

[0011] As an improvement, the material of the precipitation well core pipe is hard material, and the strength of the pipe body must meet the strength of the water flow rising and impacting the well wall outward when the water pump is pumping water and the strength of the soil on the well side wall inward squeezing; its shape can be a corrugated spiral or a smooth round wall.

[0012] As an improvement, the strength of the outer liner wall is mainly to resist the inward extrusion of the soil on the side wall of the well, and the strength of the core pipe of the dewatering well can be reduced by one level.

[0013] A method for constructing an integrated well structure with lower water intake and upper water recharging comprises the following construction steps.

[0014] Step one: Set up the drilling machinery.

[0015] Step 2: Drill the hole to the designed well depth.

[0016] Step 3: Lower the well wall pipe.

[0017] Step 4: Mechanical drilling and hole treatment and backfilling of gravel in the gaps between the wellbore pipe and the stratum.

[0018] Step 5: Place a water pump inside the well wall.

[0019] Step 6: A supply return pipe is set at the top of the wellhead and connected to the water outlet pipe.

[0020] As an improvement, the construction method of backfilling gravel outside the well wall is to provide different backfill materials on the outside of the well wall according to different soil layers to improve the functions of the upper recharge well, the lower water intake well, and the middle water-isolating chamber.

[0021] As an improvement, the backfill gravel materials from bottom to top are respectively permeable material, non-permeable material, permeable material and sealing material.

[0022] As an improvement, the depth of the permeable material is slightly lower than the depth of the permeable layer B, and the material is large-grained, rounded stone.

[0023] As an improvement, the upper part of the permeable material is a non-permeable material. The function of the non-permeable material is to cut off the hydraulic connection between the upper and lower water bodies, play the role of separating the interface, and prevent the upper recharge water body from seeping into the lower permeable layer B. The material of the non-permeable material is clay.

[0024] As an improvement, the upper permeable material of the impermeable material is the same as the lower permeable material, except that the directions of the water paths through which the upper and lower permeable materials flow are different. The direction of the lower water path is from the outside of the pipe to the inside of the pipe, while the direction of the upper water path is from the inside of the pipe to the outside of the pipe. The water flow compensates for the impermeable layer A, thereby reducing the consolidation and subsidence of the stratum caused by the drop in water level.

[0025] The advantages of the present invention over the prior art are as follows: (1) The innovative well structure of the present invention is divided into three different pipe walls: upper, middle and lower. The lower well structure is used to extract groundwater and lower the water level. The upper well structure is used to recharge the well wall to replenish the water lost in the clay layer. The middle well wall is a water-proof chamber that mainly serves to isolate the upper and lower water layers.

[0026] (2) The change of the well wall structure of the present invention requires the corresponding adjustment of the material of the backfill gravel. The backfill gravel of the well wall at the opening is made of a material with large particles and good water permeability, while the backfill gravel of the well wall without a hole is made of a material that is not water permeable and air permeable.

[0027] (3) Effectively release the water head pressure at the bottom of the foundation pit and reduce the sudden surge at the bottom of the pit. At the same time, it can also reduce the damage to the side wall retaining structure of the foundation pit caused by water flow around.

[0028] (4) The depth of the aquifer was identified, and targeted dewatering was carried out during construction, which reduced the exploitation of groundwater resources and reflected the conservation of electricity and water resources through green and environmentally friendly construction.

[0029] (5) Reduce cracks in surrounding buildings, ground subsidence, and rupture of underground pipelines caused by ground consolidation due to precipitation.

[0030] (6) Effectively reduce the construction work surface, reduce the mutual interference between different processes, and save space work surface.

[0031] (7) Reduce the construction of reinjection wells, lower the cost of well drilling and save construction time. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the shaft wall structure and backfill gravel of the present invention.

[0033] Figure 2 It is a schematic diagram of the water flow path of the present invention.

[0034] As shown in the figure: 1. Dewatering well core pipe; 1-1. Well wall pipe without holes; 1-2. Leaky well wall pipe; 2. Outer lining pipe; 2-1. Recharge flower pipe; 2-2. Middle well wall; 3. Outlet pipe; 4. Supply return pipe; 5. Sealing material; 6. Permeable material; 7. Impermeable material; A. Impermeable layer; B. Permeable layer; C. Water pump; D. Waterproof chamber. DETAILED DESCRIPTION

[0035] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0036] The invention discloses an integrated well structure for taking water from the bottom and recharging at the top, comprising a precipitation well core pipe 1, an outer lining pipe 2, a water outlet pipe 3 and a replenishment return pipe 4. A pumping device is arranged in the precipitation well core pipe 1 to discharge water in the aquifer through the water outlet pipe 3 to a designated location. The precipitation well core pipe 1 is composed of an upper non-hole well wall pipe 1-1, a middle well wall 2-2 in the middle and a lower leaky well wall pipe 1-2. The length of the leaky well wall pipe 1-2 is greater than the thickness of the aquifer. The leaky well wall pipe 1-2 is connected to the upper non-hole well wall pipe 1-1. The precipitation well core pipe 1 is made of hard material. The strength of the pipe body must meet the strength of the water flow rising to impact the well wall outward when the water pump is pumping water and the squeezing strength of the soil body on the side wall of the well inward. The shape can be a corrugated spiral or a smooth round wall.

[0037] The outer liner 2 is a cylindrical structure, the lower part of which is closely connected to the dewatering well core pipe 1. The length of the outer liner 2 is shorter than the dewatering well core pipe 1. The upper part of the outer liner 2 is a reinjection flower pipe 2-1, and the lower part is composed of a middle well wall 2-2. The length of the upper reinjection flower pipe 2-1 is greater than the depth of the impermeable layer A, and the lower part is the middle well wall 2-2. The middle well wall 2-2 is a closed well chamber, which is composed of upper, lower, left and right wall panels, and its strength can withstand water flow. impact; the middle wall 2-2 has a moderate length and its main function is to cut off the hydraulic connection between the upper recharge water and the lower aquifer water to prevent the formation of a passage; the wall of the recharge flower pipe 2-1 is a flower pipe, and its flower holes are the same size as the flower holes of the leak-type wall pipe 1-2; the middle wall 2-2 is made of impermeable material, that is, no flower holes are punched; the strength of the outer liner 2 wall is mainly to resist the inward extrusion of the soil on the side wall of the well, which can be one level lower than the strength of the precipitation well core pipe 1.

[0038] The supply return pipe 4 is connected to the outlet pipe 3. The caliber of the supply return pipe 4 should be smaller than that of the outlet pipe 3. The strength of the pipe wall is moderate to meet the downward impact force of the reinjection water flow. The material can be plastic products. The pipe wall should be located deep into the reinjection flower pipe 2-1, and its length should be 1 / 2 of the length of the reinjection flower pipe 2-1. A valve is provided on the upper part of the pipe wall. When the valve of the supply return pipe 4 is closed, the formed water flow path should flow through the outlet pipe 3 and then be discharged. When the water flow is replenished and refluxed, the valve is opened. The water flow flows into the supply return pipe 4 by its own gravity, and the water flow penetrates into the impermeable layer A through the reinjection flower pipe 2-1, replenishing the loss of water in the soil layer and reducing the subsidence and sinking of the soil. A pressure gauge is provided on the upper part of the valve of the supply return pipe 4. The opening and closing of the valve is controlled by the reading on the pressure gauge, so as to know the reinjection amount of the water body.

[0039] A method for constructing an integrated well structure with lower water intake and upper water recharging comprises the following construction steps.

[0040] Step one: Set up the drilling machinery.

[0041] Step 2: Drill the hole to the designed well depth.

[0042] Step 3: Lower the well wall pipe.

[0043] Step 4: Mechanically drill holes and treat the gaps between the wellbore pipes to backfill the strata with gravel. Before backfilling the gravel, the depths of the impermeable layer A and the permeable layer B must be clearly determined, so that the depths of the backfill materials in different locations can be accurately known.

[0044] Step 5: Place a water pump inside the well wall.

[0045] Step 6: A supply return pipe is set at the top of the wellhead and connected to the water outlet pipe.

[0046] The construction method of backfilling gravel outside the well wall is to provide different backfill materials on the outside of the well wall according to different soil layers to improve the functions of the upper recharging well, the lower water intake well, and the middle water-isolating chamber. The backfill gravel materials are permeable material 6, non-permeable material 7, permeable material 6, and plugging material 5 from bottom to top. The depth of permeable material 6 is slightly lower than the depth of permeable layer B, and its material is large-grained, rounded stone.

[0047] The upper part of the permeable material 6 is the impermeable material 7, which has the function of isolating the hydraulic connection between the upper and lower water bodies, playing the role of separating the interface, and preventing the upper recharge water from seeping into the lower permeable layer B. The impermeable material is made of clay.

[0048] The upper permeable material 6 of the impermeable material 7 is the same as the lower permeable material 6, except that the directions of the water paths through which the upper and lower permeable materials flow are different. The direction of the lower water path is from the outside of the pipe to the inside of the pipe, while the direction of the upper water path is from the inside of the pipe to the outside of the pipe. The water flow compensates for the impermeable layer A, thereby reducing the consolidation and subsidence of the stratum caused by the drop in water level.

[0049] The depth of the impermeable material 7 is slightly lower than the upper permeable layer B. The uppermost part of the gravel backfill outside the pipe wall is the plugging material 5, which is made of clay soil with a smaller gravel diameter, and mainly plays a plugging role in the gap between the hole and the end of the pipe wall. The density of the plugging material is greater than that of the impermeable material 7, and its gravel diameter is smaller than that of the impermeable material 7.

[0050] During specific use, a water pump is used to discharge the water in the permeable layer through the leaky well wall pipe 1-2 in an organized manner to the designated drain outlet. The water passes through the precipitation well core pipe 1 and the drainage outlet pipe 3 to the designated drain outlet. As the number of precipitation wells started increases, the water level at the bottom of the foundation pit approaches the design water level. The outlet pipe switch is closed, and the supply return pipe switch is opened to recharge the water that should have been discharged to the surrounding impermeable layer. That is, the water then flows through the supply return pipe 4 to the recharge flower pipe 2-1 to recharge the surrounding impermeable layer A. In order to complement the interference between the recharged well water and the discharged target water, this invention specially adds a middle well wall 2-2. The middle well wall 2-2 is located at the bottom of the outer liner 2. The middle well wall 2-2 plays the role of a water barrier to divide the pumped groundwater and the recharged water into two upper and lower interfaces, that is, they are not connected and do not interfere with each other.

[0051] Due to the different amounts of water attached to the formation, the backfill material outside the well wall in the present invention should be appropriately adjusted. The backfill gravel material at the leaky well wall pipe 1-2 of the permeable layer B is a permeable material with good roundness. The backfill gravel material at the septum well wall 2-2 is a non-permeable material. The main function is to reduce the infiltration of the upper recharge water. Ensure that the water level in the aquifer drops, while the water content in the upper non-permeable layer A remains stable. The backfill gravel material of the non-hole well wall pipe 1-1 on the upper part of the septum well wall 2-2 is also made of a permeable material with good roundness, mainly to recharge water into the non-permeable layer A.

[0052] Example 1: Coastal areas.

[0053] The stratigraphic structure consists of thick silty soil in the upper part, clay interlayers in the middle part, and a fairly thick sand layer in the lower part.

[0054] The general construction idea is to set up a suspended water-stop curtain around the foundation pit and conduct pipe well dewatering at the bottom of the foundation pit. However, in specific construction applications, the amount of water gushing from the foundation pit to the bottom is very large, and it is not easy to raise the water level to the designed elevation. At this time, the present invention is applied to apply the well construction method of bottom water intake and top recharge outside the foundation pit, which mainly reduces the water head pressure at the bottom of the foundation pit and secondly reduces the harm caused by the consolidation of the stratum around the upper part of the foundation pit.

[0055] Example 2: Subway shield section.

[0056] The upper part of the stratum structure is a sand layer, the middle part is a clay layer, and the lower part is weathered rock. Traditional precipitation construction is to dig a pipe well to lower the water level in the sand layer, but the head pressure in the weathered rock is difficult to release. If an ultra-deep precipitation well is dug, not only will the construction difficulty coefficient be large, but it will also bring about a large amount of water resources. The problem of difficulty in draining out. At this time, the present invention is applied to apply a well construction method of bottom water intake and top recharge around the subway shield section, and the lower bedrock fissure water is pumped out and recharged into the upper sand layer, releasing the head pressure in the rock and saving the exploitation of groundwater resources in the sand layer.

[0057] Embodiment 3: Dark excavation tunnel.

[0058] In the construction of underground tunnels in municipal engineering, small-duct grouting reinforcement technology is often used to reinforce the strata, and construction dewatering technology is not used. However, when encountering a scene with bedrock fissure water, the well construction method of the present invention, i.e., bottom water intake and top water recharge, is applied without affecting the consolidation of the surrounding strata to release the water head pressure in the rock and reduce the consolidation settlement of the surface.

[0059] The present invention and its embodiments are described above, and such description is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. In short, if ordinary technicians in the field are inspired by it, without departing from the purpose of the invention, they can design a structure and embodiment similar to the technical solution without creativity, which should belong to the protection scope of the present invention.

Claims

1. An integrated well structure with water intake at the bottom and recharging at the top, characterized in that: The invention comprises a dewatering well core pipe (1), an outer lining pipe (2), a water outlet pipe (3), and a replenishment return pipe (4). A pumping device is arranged in the dewatering well core pipe (1) to discharge water in the aquifer through the water outlet pipe (3) to a designated location. The dewatering well core pipe (1) is composed of an upper non-hole well wall pipe (1-1), a middle well wall (2-2) and a lower leaky well wall pipe (1-2). The length of the leaky well wall pipe (1-2) is greater than the thickness of the aquifer. The leaky well wall pipe (1-2) is connected to the upper non-hole well wall pipe (1-1). The outer liner (2) is a cylindrical structure, the lower part of which is closely connected to the dewatering well core pipe (1). The length of the outer liner (2) is shorter than that of the dewatering well core pipe (1). The upper part of the outer liner (2) is a reinjection flower pipe (2-1), and the lower part is composed of a septum well wall (2-2). The length of the upper reinjection flower pipe (2-1) is greater than the depth of the impermeable layer A. The lower part is the septum well wall (2-2). The septum well wall (2-2) is A closed well chamber is composed of upper, lower, left and right wall plates, and its strength can withstand the impact of water flow; the middle well wall (2-2) is of moderate length and its main function is to cut off the hydraulic connection between the upper recharge water body and the lower aquifer water body to prevent the formation of a passage; the well wall of the recharge flower pipe (2-1) is a flower pipe, and its flower holes are the same size as the flower holes of the leak-type well wall pipe (1-2); the middle well wall (2-2) is made of impermeable material, that is, no flower holes are drilled; The supply return pipe (4) is connected to the outlet pipe (3); the diameter of the supply return pipe (4) is smaller than the diameter of the outlet pipe (3); the pipe wall is positioned deep into the recharging flower pipe (2-1); and its length is 1 / 2 of the length of the recharging flower pipe (2-1); a valve is provided on the upper part of the pipe wall.

2. The integrated well structure for bottom water intake and top water recharging according to claim 1, characterized in that: The material of the precipitation well core pipe (1) is a hard material, and the strength of the pipe body must meet the strength of the water flow rising and impacting the well wall outwards when the water pump is pumping water, and the strength of the soil on the well side wall squeezing inwards; its shape can be a corrugated spiral or a smooth round wall.

3. The integrated well structure for bottom water intake and top water recharging according to claim 1, characterized in that: The strength of the well wall of the outer liner pipe (2) is mainly to resist the inward squeezing of the soil on the well side wall, and can be one level lower than the strength of the well core pipe (1).

4. A method for constructing an integrated well structure with water intake from the bottom and recharging from the top, characterized in that: The construction steps include: Step 1: Set up the well drilling machinery; Step 2: Drill the hole to the designed well depth; Step 3: Lower the well wall pipe; Step 4: Mechanical drilling and hole treatment of the gap between the well wall and the pipe, backfilling the stratum with gravel; Step 5: Place a water pump inside the well wall; Step 6: A supply return pipe is set at the top of the wellhead and connected to the water outlet pipe.

5. The method for constructing an integrated well structure with bottom water intake and top water recharging according to claim 4, characterized in that: The construction method of backfilling gravel outside the well wall is to provide different backfill materials on the outside of the well wall according to different soil layers to improve the functions of the upper recharge well, the lower water intake well and the middle water-isolating chamber.

6. The method for constructing an integrated well structure with bottom water intake and top water recharging according to claim 4, characterized in that: The backfill gravel materials are, from bottom to top, easily permeable material (6), impermeable material (7), easily permeable material (6), and plugging material (5).

7. The method for constructing an integrated well structure with bottom water intake and top water recharging according to claim 6, characterized in that: The depth of the permeable material (6) is slightly lower than the depth of the permeable layer B, and the material thereof is large-grained, rounded stone.

8. The method for constructing an integrated well structure with bottom water intake and top water recharging according to claim 6, characterized in that: The upper part of the permeable material (6) is a non-permeable material (7). The function of the non-permeable material (7) is to cut off the hydraulic connection between the upper and lower water bodies, play the role of separating the interface, and prevent the upper recharged water body from seeping into the lower permeable layer body B. The non-permeable material is made of clay.

9. The method for constructing an integrated well structure with bottom water intake and top water recharging according to claim 6, characterized in that: The upper permeable material (6) of the impermeable material (7) is the same as the lower permeable material (6), except that the directions of the water paths through which the upper and lower permeable materials flow are different. The direction of the lower water path is from the outside of the pipe to the inside of the pipe, while the direction of the upper water path is from the inside of the pipe to the outside of the pipe. The water flow compensates for the impermeable layer A, thereby reducing the consolidation and subsidence of the stratum caused by the drop in water level.

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