Layered water stopping method

Abstract

The invention relates to the technical field of dewatering well layered water stopping, in particular to a layered water stopping method which comprises the steps that S1, construction preparation is conducted; s2, the well position is measured, and a mouth protection pipe is buried; s3, installing a drilling machine, and drilling to form a well; s4, hole cleaning is conducted, specifically, after drilling is conducted, hole cleaning equipment is used for flushing the side wall of the well hole, an annular pit is dug in the pre-designed layered water stop position in a punching mode, and then sundries and slurry in the hole are removed; s5, a well pipe is lowered, and after hole cleaning is completed, the well pipe is installed; s6, filling a filter material, namely filling medium-coarse sand with relatively good roundness on the steel filter pipe as the filter material; s7, grouting and water stopping; s8, backfilling and well cementation, pump installation and pumping trial, and layered water stop reliability inspection; the tracer agent is injected into the position above the water stop section, whether the tracer agent is mixed in pumped water or not is observed in a pit water pumping mode, and therefore whether water stop fails or not is judged, cost is low, use is convenient, and observation is easy, convenient and effective.

Description

Technical Field

[0001] The present invention relates to the technical field of layered water sealing for precipitation wells, and particularly to a method for layered water sealing. Background Art

[0002] A precipitation well refers to a well drilled for precipitation. After completion, a water pump is placed to pump out groundwater to lower the groundwater level. Precipitation wells can prevent the occurrence of outburst failures such as quicksand and piping caused by groundwater seepage. They can reduce the hydrostatic pressure and seepage acting on the slope or the retaining structure of the pit wall, thereby improving the stability of the slope or the retaining structure of the pit wall. During the construction of precipitation wells, in order to ensure the sealing effect outside the well wall of the precipitation well, grouting layered water sealing measures are adopted to avoid the accident of water gushing outside the well wall during the excavation of the foundation pit.

[0003] Therefore, after the layered water sealing is completed, detection is required. In the prior art, some common inspection methods include, for example, the pressure test method: by injecting high-pressure water or air into the grouting hole and observing the pressure change to judge the grouting effect. When the pressure drop rate is lower than a certain value (such as 5%), the grouting effect can be considered good. The sampling detection method: by drilling samples of the grouting body and observing its density, strength and other indicators to evaluate the grouting quality. The compressive strength of the grouting body should reach more than 80% of the design requirements. The permeability test method: by measuring the permeability coefficient of the grouting body to evaluate its water sealing performance. The permeability coefficient should be lower than a certain value to meet the water sealing requirements. However, these methods are cumbersome to operate, have a high equipment input cost, are inconvenient to use, have slow detection feedback, and affect the construction efficiency. Summary of the Invention

[0004] The purpose of the present invention is to solve the disadvantages existing in the prior art and to propose a method for layered water sealing.

[0005] In order to achieve the above purpose, the present invention adopts the following technical solutions: A method for layered water sealing includes the steps: S1. Construction preparation, understanding the engineering geological conditions and hydrogeological conditions to provide guidance for construction; S2. Measuring and setting the well position and burying the casing pipe, measuring and setting the position of the dewatering well and making marks, and burying the casing pipe at the measured well position to protect the wellhead; S3. Installing the drilling rig and drilling the well, installing the drilling rig at the measured well position and using the drilling rig to drill to form the well hole of the dewatering well; S4. Cleaning the hole, after drilling, using the hole cleaning equipment to wash the side wall of the well hole and excavate an annular pit at the pre-designed layered water sealing position, and then removing the sundries and mud in the hole; S5. Lowering the well pipe, after the hole cleaning is completed, installing the well pipe; the well pipe includes a solid steel pipe and a steel filter pipe. The hole depth needs to be measured before lowering the well pipe to ensure that the hole depth meets the design requirements; S6. Surround and fill the filter material. Surround and fill medium-coarse sand with good roundness around the steel filter pipe as the filter material. S7. Grout for water stop. Mix the grouting material evenly according to the design ratio, and use a grouting pump to inject the mixed grouting material into the hole to fill the annular pit. During the grouting process, the grouting pressure is generally controlled between 0.5 and 1.5 MPa. S8. Backfill and cement the well, install the pump and conduct a trial pumping, and conduct a reliability test on the layered water stop; check the reliability of the layered water stop of the dewatering well. Inject a tracer above the water stop section, and observe whether the pumped water contains the tracer by pumping water in the pit. If it is found, it is judged that the water stop may fail, and deal with it in time to ensure that the construction process meets the water stop requirements.

[0006] Preferably, in step S8, for the reliability test of the layered water stop, it is carried out by directly injecting a tracer above the water stop section after grouting, and the tracer uses a dye. The specific steps include: A1. For the selected dewatering well for inspection, embed a grouting pipe in advance during the well construction. The grouting pipe can be a 1-inch PE pipe. For the dewatering well that has been constructed, it is processed by re-drilling a hole and injecting a dye. A2. Open holes on the pipe wall of the grouting pipe, and wrap filter cloth after opening the holes to prevent grouting failure and avoid blocking the holes during backfilling, resulting in failure of injecting the tracer. A3. The range of the holes opened on the grouting pipe should be greater than 2 m to prevent blockage at the bottom due to grouting for water stop. A4. After the grouting for water stop solidifies, before backfilling around the well, use a grouting machine to inject the tracer. A5. After the injection is completed, pump water through a water pump to verify the effect of the layered water stop; in addition to pumping water from this test well, the dewatering wells at the same location are pumped together to ensure that the tracer can be observed in the dewatering wells.

[0007] Preferably, in step S4, the hole cleaning device includes a mud pipe, a water spray pipe and a cutter cage. The water spray pipe is movably arranged inside the mud pipe. The upper and lower sides of the cutter cage are respectively connected to the mud pipe and the water spray pipe. The cutter cage is processed by circumferentially arranging elastic metal sheets.

[0008] Preferably, a three-way joint is provided at the top of the mud pipe. A connecting cover is provided at the top of the three-way joint. The water spray pipe penetrates through the connecting cover and is slidably connected therebetween. A regulator is provided on the water spray pipe, and a nozzle is provided at the bottom end of the water spray pipe.

[0009] Preferably, a turntable is provided on the upper side of the casing pipe. A clamp is provided on the upper side of the turntable. The bottom of the turntable is in contact with the ground.

[0010] Preferably, the usage method of the hole cleaning device includes: a. After drilling, install the casing pipe, place the rotary table, assemble the mud pipe and the water spray pipe, lower the pipe fittings into the well hole, and clamp the mud pipe with a fixture; b. Connect the water spray pipe to the water supply equipment to spray water flow, rotate the rotary table, control the nozzle to wash the mud blocks in the well hole, connect the mud pipe to the negative pressure pump, extract the mud water and discharge it; c. The regulator changes the relative height between the mud pipe and the water spray pipe, changes the shape of the cutter cage, and when rotating the rotary table, scrapes the inner wall of the well hole to form an annular pit, which is convenient for grouting and water stop; d. Clear the hole again. After the well pipe is lowered, carry out the hole cleaning work again. The water spray pipe sprays water, and the mud pipe extracts mud to reduce the mud and soil blocks in the well pipe.

[0011] Preferably, in the step S5, the steel filter pipe is a bridge-type filter pipe, wrapped with a 60-mesh nylon filter screen on the outside. A centralizer is provided on the outside of the steel filter pipe, a connecting flared opening is provided at the top of the steel filter pipe, and a blanking plug is provided at the bottom of the steel filter pipe.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The present invention digs an annular pit at the layered water stop by the hole cleaning equipment, improves the reliability of grouting and water stop, increases the grouting volume through the complex curved surface of the annular pit, makes the concrete and the soil combine tightly, ensures the sealing effect of the layered water stop, and at the same time stably fixes the well pipe; 2. The present invention injects a tracer above the water stop section, and by pumping water in the pit, observes whether the pumped water is mixed with the tracer, so as to determine whether the water stop fails. The cost is low, the use is convenient, and the observation is simple, convenient and effective. Description of the Drawings

[0013] Figure 1 It is a schematic construction state diagram of a layered water stop method proposed by the present invention; Figure 2 is Figure 1 a partial enlarged view of part A in Figure 3 is Figure 1 a partial enlarged view of part B in Figure 4 It is a schematic front sectional structure diagram of the hole cleaning equipment involved in a layered water stop method proposed by the present invention; Figure 5 It is a schematic structure diagram of the completed state of a dewatering well of a layered water stop method proposed by the present invention; Figure 6 It is a working flow chart of a layered water stop method proposed by the present invention.

[0014] In the figure: 1, turntable; 11, fixture; 2, solid steel pipe; 3, steel filter pipe; 4, filter material; 5, hole cleaning equipment; 51, mud pipe; 52, water spray pipe; 53, tee joint; 531, connecting cover; 54, regulator; 55, nozzle; 56, cutter cage; 6, foundation soil; 7, backfill soil; 8, casing pipe; 9, layered water-stop section. Specific implementation manner

[0015] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and in no way limits the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0016] Refer to Figures 1-6 , a layered water-stop method, including the steps of: S1. Construction preparation, geological exploration, design scheme and material preparation, consult relevant geological and hydrological data, understand the engineering geological conditions and hydrogeological conditions, and provide guidance for construction; S2. Measure and set the well position and bury the casing pipe 8. According to the design requirements, accurately measure and set the position of the pressure relief well at the construction site and make marks. On the measured well position, bury the casing pipe 8 to protect the wellhead and prevent surface sewage from seeping into the well. The casing pipe 8 should be a certain height above the ground, such as 0.5 m, and be sealed with high-quality clay or cement slurry; S3. Install the drilling rig and drill the well. Install the drilling rig on the measured well position and adjust the angle and height of the drilling rig. During the entire construction process, ensure the verticality and accuracy of the drilling. Use the drilling rig to drill on the foundation soil 6 to form the well hole of the pressure relief well; during the drilling process, it is necessary to control the density of the mud, such as 1.10 - 1.15, generally preferably 1.12, to prevent the collapse of the hole wall and ensure the quality of the well hole; There is a turntable 1 on the upper side of the casing pipe 8, and a fixture 11 on the upper side of the turntable 1. The fixture 11 is used to fix the pipe fittings. There is a plain bearing in the middle of the turntable 1, and the bottom of the turntable 1 is in contact with the ground; S4. Hole cleaning. After drilling, use the hole cleaning equipment 5 to wash the side wall of the well hole and excavate an annular pit at the pre-designed layered water-stop position. Then, remove the sundries and mud in the hole. The hole cleaning is divided into primary hole cleaning and secondary hole cleaning to ensure that the hole is clean without sundries; The hole cleaning device 5 includes a mud pipe 51, a water spray pipe 52 and a cutter cage 56. The water spray pipe 52 is movably arranged inside the mud pipe 51 and can slide relative to each other. The mud pipe 51 is fixed by a clamp 11 and its height can be adjusted as required. The upper and lower sides of the cutter cage 56 are respectively connected to the mud pipe 51 and the water spray pipe 52. The cutter cage 56 is processed by circular array of elastic metal sheets and can be bent into a C shape. A three-way joint 53 is provided at the top of the mud pipe 51, and a connecting cover 531 is provided at the top of the three-way joint 53. The water spray pipe 52 passes through the connecting cover 531 and is slidably connected therebetween. By pulling the water spray pipe 52, the diameter of the cutter cage 56 can be changed. A regulator 54 is provided on the water spray pipe 52 for adjusting and then fixing the relative height between the water spray pipe 52 and the mud pipe 51. A nozzle 55 is provided at the bottom end of the water spray pipe 52 for forming a high-pressure water flow to spray and clean the wall base soil 6. The usage method of the hole cleaning device 5 includes: a. After drilling, install the casing pipe 8, place the rotary table 1, assemble the mud pipe 51 and the water spray pipe 52, lower the pipe fittings into the well hole, and clamp the mud pipe 51 by the clamp 11. b. Connect the water spray pipe 52 to the water supply equipment to eject water flow, rotate the rotary table 1, control the nozzle 55 to wash the mud blocks in the well hole, connect the mud pipe 51 to the negative pressure pump, extract the mud water and discharge it. c. The regulator 54 changes the relative height between the mud pipe 51 and the water spray pipe 52, changes the shape of the cutter cage 56, and when rotating the rotary table 1, scrapes the inner wall of the well hole to form an annular pit for facilitating grouting and water stop. d. Clean the hole again. After lowering the well pipe, carry out the hole cleaning work again. The water spray pipe 52 sprays water, and the mud pipe 51 extracts mud to reduce the mud and soil blocks in the well pipe. S5. Lower the well pipe. After the hole cleaning is completed, install the well pipe. The well pipe includes a solid steel pipe 2 and a steel filter pipe 3. The steel filter pipe 3 is a bridge-type filter pipe, with a 60-mesh nylon filter screen wrapped outside. A connecting flared mouth is provided at the top of the steel filter pipe 3. Before lowering the well pipe, it is necessary to measure the hole depth to ensure that the hole depth meets the design requirements. When lowering the well pipe, a set of centralizers should be provided at each of the upper and lower ends outside the steel filter pipe 3. The centralizer is made of a U-shaped metal strip, with at least three groups, welded outside the steel filter pipe 3, for maintaining the distance between the steel filter pipe 3 and the well wall to ensure that the steel filter pipe 3 can be centered. Clean the hole again. After lowering the well pipe, carry out the hole cleaning work again to ensure that there is no debris and mud in the well pipe. S6. Surround and fill the filter material 4. Surround and fill well-rounded medium and coarse sand at the position of the steel filter pipe 3 as the filter material 4. Before filling the filter material 4, it is necessary to lower the drill pipe to a certain height from the bottom of the hole, such as 0.3 - 0.5 m, generally preferably 0.4 m, and add a plug to seal it. Pump mud from the drill pipe, dilute the mud gradually while flushing the hole, and then fill the filter material 4 according to the design requirements, and measure the height of the filled filter material 4 while filling. S7. Grouting for water stoppage. Mix the grouting materials evenly according to the design ratio, and use a grouting pump to inject the mixed grouting materials into the holes to fill the annular pits, improving the reliability of water stoppage by grouting. During the grouting process, it is necessary to control the grouting pressure and the grouting volume to ensure the grouting effect. The grouting pressure is generally controlled between 0.5 and 1.5 MPa, and 1 MPa is generally preferred. The specific value depends on the actual situation of the foundation and the design requirements.

[0017] S8. Backfill and cement the well, install the pump and conduct a trial pumping, and conduct a reliability inspection of layered water stoppage; after the grouting for water stoppage solidifies, use drill cuttings or site soil to backfill to the ground surface and tamp it. The backfill soil prevents ground settlement caused by pumping phreatic water. At the same time, do a good job in sealing outside the wellhead pipe; Wash the well until the water discharged from the well pipe changes from turbid to clear, and the well washing is completed. Install the water pump for trial pumping. During the trial pumping process, it is necessary to observe the operation of the water pump and the water output of the well to ensure that the dewatering well can meet the design requirements. Through the pumping test, measure the single-well water inflow of each aquifer, observe the relationship between the water level drop and the water inflow, reasonably configure the water pump, and guide the operation and management of the foundation pit dewatering; during the test, observe the water level drop outside the pit when pumping water in the pit to initially judge the sealing effect of the sealing section of the water-stop curtain; infer the hanging section and the impact degree of the dewatering in the pit on the surrounding environment; Inspect the reliability of layered water stoppage of the dewatering well to ensure that the construction technology meets the water stoppage requirements; for the reliability inspection of layered water stoppage, adopt the method of directly injecting a tracer above the water-stop section after grouting. The tracer uses a food-grade dye to reduce environmental pollution; The specific steps include: A1. For the selected test dewatering well, embed a grouting pipe in advance during the well completion construction. The grouting pipe can use a 1-inch PE pipe. For the dewatering well that has been constructed, use the method of re-drilling a hole to inject the dye for treatment; A2. Open holes on the pipe wall of the grouting pipe, and wrap filter cloth after opening the holes to prevent grouting failure. At the same time, avoid blocking the opened holes during backfilling, resulting in the failure of injecting the tracer; A3. The range of the holes opened on the grouting pipe should be greater than 2 m to prevent blockage at the bottom due to grouting for water stoppage; A4. After the grouting for water stoppage solidifies and before backfilling around the well, use a grouting machine to inject the tracer; A5. After the injection is completed, pump water through the water pump to verify the effect of layered water stoppage; in addition to pumping water from this test well, the dewatering wells at the same location are pumped together to ensure that the tracer can be observed in the dewatering wells.

[0018] By injecting the tracer above the water-stop section and observing whether the pumped water will be mixed with the tracer by pumping water in the pit. If it is found, it is judged that the water stoppage may fail and deal with it in time.

[0019] If the water stoppage fails, it is necessary to temporarily block, drain and decompress; According to the actual situation of the leakage point, use materials such as quick-setting cement and ordinary cement admixed with accelerating agents to temporarily plug the leakage point; if the leakage point is large, first use water-stop materials to narrow the scope and then plug it.

[0020] Set a drainage pipe at the leakage point to drain the water to a safe area. If the leakage is serious, consider driving a grouting pipe outside the leakage point for grouting plugging or use high-pressure jet grouting for reinforcement.

[0021] At the same time, conduct a detailed investigation into the reasons for the failure of water-stop, including checking whether there are problems with water-stop materials, water-stop technology, dewatering well design, etc., and analyzing whether there are water-resistant layers or other geological factors causing difficulties in water-stop; if the dewatering well design is unreasonable, it is necessary to redesign the dewatering well, increase the number of dewatering wells or adjust the well spacing, clean the sundries and sediments in the dewatering well, and keep the dewatering well unobstructed.

[0022] Conduct long-term monitoring of the treated dewatering wells and water-stop effect to ensure the success of water-stop and maintain a good dewatering effect; regularly check the operation status of the dewatering wells and water-stop facilities, and promptly discover and handle problems.

[0023] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, making equivalent substitutions or changes, should be covered by the protection scope of the present invention.

[0024] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0025] Unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be understood that, for the sake of convenience in description, the dimensions of the various parts shown in the drawings are not drawn in actual proportional relationships. Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the said technologies, methods, and devices should be regarded as part of the authorization specification. In all the examples shown and discussed here, any specific value should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numerals and letters denote like items in the following drawings, and thus, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

Claims

1. A layered water stop method, characterized in that Including the steps: S1. Construction preparation, understanding the engineering geological conditions and hydrogeological conditions to provide guidance for construction; S2. Measuring and setting the well positions and burying the casing pipe (8), measuring and setting the positions of the dewatering wells, making marks, and burying the casing pipe (8) at the measured and set well positions to protect the wellhead; S3. Installing the drilling rig and drilling the well, installing the drilling rig at the measured and set well positions, and using the drilling rig to drill to form the wellbore of the dewatering well; S4. Well cleaning, after drilling, using the well cleaning equipment (5) to wash the side wall of the wellbore, and excavating an annular pit at the pre-designed stratified water-stop position, and then removing the sundries and mud in the hole; S5. Lowering the well pipe, after well cleaning is completed, installing the well pipe; the well pipe includes a solid steel pipe (2) and a steel filter pipe (3), and the hole depth needs to be measured before lowering the well pipe to ensure that the hole depth meets the design requirements; S6. Surrounding and filling the filter material (4), surrounding and filling medium-coarse sand with good roundness at the position of the steel filter pipe (3) as the filter material (4); S7. Grouting for water stop, mixing the grouting materials evenly according to the design ratio, using a grouting pump to inject the mixed grouting materials into the hole to fill the annular pit. During the grouting process, the grouting pressure is generally controlled between 0.5 and 1.5 MPa; S8. Backfilling and cementing the well, installing the pump and conducting trial pumping, and inspecting the reliability of stratified water stop; inspecting the reliability of stratified water stop of the dewatering well, injecting a tracer at a position above the water-stop section, and observing whether the pumped water contains the tracer by pumping water in the pit. If it is found, it is judged that the water stop may fail and timely treatment should be carried out to ensure that the construction process meets the water-stop requirements.

2. The layered water stop method according to claim 1, characterized in that, In the step S8, for the inspection of the reliability of stratified water stop, it is inspected by directly injecting a tracer at a position above the water-stop section after grouting, and the tracer adopts a dye; The specific steps include: A1. For the selected inspection dewatering well, a grouting pipe is buried in advance during the well construction. The grouting pipe can adopt a 1-inch PE pipe. For the already constructed dewatering well, it is treated by re-drilling a hole and injecting a dye; A2. Opening holes on the pipe wall of the grouting pipe, and winding filter cloth after opening the holes to prevent grouting failure and avoid blocking the opened holes during backfilling, resulting in failure of injecting the tracer; A3. The range of the opened holes on the grouting pipe should be greater than 2 m to prevent blockage at the bottom due to grouting for water stop; A4. After the grouting for water stop solidifies, before backfilling around the well, use a grouting machine to inject the tracer; A5. After the injection is completed, pump water through a water pump to verify the effect of stratified water stop; except for pumping water from this test well, the dewatering wells at the same position are pumped together to ensure that the tracer can be observed in the dewatering wells.

3. A layered water stop method according to claim 1, characterized in that, The well cleaning equipment (5) in the step S4 includes a mud pipe (51), a water spray pipe (52) and a cutter cage (56). The water spray pipe (52) is movably arranged inside the mud pipe (51). The upper and lower sides of the cutter cage (56) are respectively connected with the mud pipe (51) and the water spray pipe (52). The cutter cage (56) is processed by circularly arranging elastic metal sheets.

4. The layered water stop method according to claim 3, characterized in that, A tee joint (53) is provided at the top of the mud pipe (51). A connection cover (531) is provided at the top of the tee joint (53). The water spray pipe (52) passes through the connection cover (531) and is slidably connected therebetween. A regulator (54) is provided on the water spray pipe (52). A spray head (55) is provided at the bottom end of the water spray pipe (52).

5. A layered water stop method according to claim 4, characterized in that, A turntable (1) is provided on the upper side of the casing pipe (8). A clamp (11) is provided on the upper side of the turntable (1). The bottom of the turntable (1) is in contact with the ground.

6. The layered water stop method according to claim 5, characterized in that, The usage method of the hole cleaning device (5) includes: a. After drilling, install the casing pipe (8), place the turntable (1), assemble the mud pipe (51) and the water spray pipe (52), lower the pipe fittings into the well hole, and clamp the mud pipe (51) through the clamp (11); b. Connect the water spray pipe (52) to the water supply device to spray water flow, rotate the turntable (1), control the spray head (55) to wash the mud blocks in the well hole, connect the mud pipe (51) to the negative pressure pump, extract the mud water and discharge it; c. The regulator (54) changes the relative height between the mud pipe (51) and the water spray pipe (52), changes the shape of the cutter cage (56), and scrapes the inner wall of the well hole when rotating the turntable (1) to form an annular pit for facilitating grouting and water stop; d. Clean the hole again. After lowering the well pipe, carry out the hole cleaning work again. The water spray pipe (52) sprays water, and the mud pipe (51) extracts the mud to reduce the mud and soil blocks in the well pipe.

7. A layered water stop method according to claim 1, characterized in that, In the step S5, the steel filter pipe (3) is a bridge type filter pipe, which is wrapped with a 60-mesh nylon filter screen. A centralizer is provided on the outer side of the steel filter pipe (3). A connection flare is provided at the top of the steel filter pipe (3). A plug is provided at the bottom of the steel filter pipe (3).

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