Drainage well in foundation pit and construction method thereof
By installing a dewatering well structure with sand-free concrete pipes and pumping equipment inside the foundation pit, the leakage problem of the foundation raft slab during the construction of the dewatering well inside the foundation pit was solved, achieving the effects of reducing leakage risk and facilitating construction.
Patent Information
- Application Number
- CN202410744734.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-11
- Publication Date
- 2025-12-12
AI Technical Summary
In existing technologies, the dewatering wells in the foundation pit need to pass through the foundation raft and foundation cushion layer during construction, which makes the waterproofing of the foundation raft difficult, poses a risk of leakage, and cannot meet the requirements of modern construction.
Horizontal trenches and vertical channels are set below the foundation in the pit. Sand-free concrete pipes and pumping equipment are used to lay water pipes through the trenches to form dewatering well pipes. Nylon filters and gravel filters are installed inside the concrete pipes to seal the concrete openings and prevent them from penetrating the foundation raft and cushion layer.
It effectively improves the integrity of the foundation raft slab, reduces the risk of leakage, is suitable for high groundwater levels and heavy rainfall, saves costs, and is easy to construct.
Smart Images
Figure CN121110698A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of dewatering well construction technology, and in particular to a dewatering well in a foundation pit and its construction method. Background Technology
[0002] Currently, most methods for dewatering foundation pits involve setting up dewatering wells around the pit. In cases of high groundwater levels or heavy rainfall, dewatering wells need to be installed inside the pit to keep the foundation dry. However, during foundation raft slab construction, conventional dewatering wells within the pit must penetrate the foundation cushion and raft slab, posing significant challenges to waterproofing the raft slab and potentially leading to future leaks. This method no longer meets current construction requirements. Therefore, it is necessary to propose a new method for creating dewatering wells within foundation pits and its construction to address these issues.
[0003] Definitions of abbreviations and key terms
[0004] Dewatering well: A dewatering well is a type of dewatering well, which is a method of artificially lowering the groundwater level. It is used to collect rainwater in the foundation pit and lower the groundwater level. Summary of the Invention
[0005] In order to overcome the above-mentioned defects of the prior art, the technical problem to be solved by the embodiments of the present invention is to provide a drainage well in the foundation pit and its construction method, which can improve the integrity of the foundation raft and reduce the possibility of leakage of the foundation raft.
[0006] The specific technical solution of this invention is as follows:
[0007] A dewatering well within a foundation pit, the dewatering well within the foundation pit comprising:
[0008] The base located within the foundation pit has horizontally extending grooves and openings at a height below the base elevation;
[0009] A vertical channel is opened within the foundation pit, below the base elevation, corresponding to the opening position;
[0010] A sand-free concrete pipe body is installed in the channel;
[0011] Pumping equipment installed inside the sand-free concrete pipe;
[0012] A water intake pipe, one end of which is connected to the outlet of the pumping equipment, and the other end of which extends upward, bends through the opening, and is laid in the trench. The upper part of the concrete pipe body and the opening are sealed with concrete.
[0013] Preferably, the trench is filled with a first type of crushed stone; the dewatering well in the foundation pit includes:
[0014] A concrete cushion layer, which is cast on top of the base.
[0015] Preferably, the dewatering well within the foundation pit further includes:
[0016] A nylon filter screen is installed on the outer wall of the sand-free concrete pipe.
[0017] Preferably, the nylon filter screen has a mesh size between 100 and 150.
[0018] Preferably, the space between the channel and the sand-free concrete pipe is filled with a second type of crushed stone, the particle size of which is between 2 mm and 4 mm.
[0019] Preferably, the sand-free concrete pipe is filled with a third type of crushed stone, the particle size of which is between 15mm and 30mm.
[0020] Preferably, fine sand is filled between the upper part of the concrete pipe used for sealing and the third crushed stone.
[0021] Preferably, the trench extends all the way to the foundation pit trough, so that the water intake pipe is led through the foundation pit trough to the drainage network outside the foundation pit.
[0022] A method for constructing a dewatering well within a foundation pit, the method comprising the following steps:
[0023] Drilling machinery is used to drill holes at the base of the foundation pit to form channels;
[0024] A sand-free concrete pipe is lowered into the duct until the base elevation is reached;
[0025] A second type of crushed stone is filled between the sand-free concrete pipe and the channel;
[0026] After the second crushed stone is filled, the well is flushed inside the sand-free concrete pipe.
[0027] After the well washing operation is completed, a pumping device connected to a water suction pipe is lowered into the sand-free concrete pipe body.
[0028] The foundation pit is excavated. When the foundation pit is excavated to the designed elevation of the base, the sand-free concrete pipe body in the foundation pit that is higher than the base elevation is cut off, and a trench extending horizontally to the foundation pit trench is dug at a height below the base.
[0029] The water pipe is laid along the trench into the foundation pit and connected to the drainage network outside the foundation pit.
[0030] After the water pipe is laid, a third type of crushed stone is filled into the sandless concrete pipe until the upper part of the sandless concrete pipe is filled with fine sand, and then concrete is poured to the elevation of the base.
[0031] The trench was filled with crushed stone and compacted. Then, a concrete cushion layer was poured on the base in the pit, followed by normal waterproofing and foundation raft slab construction.
[0032] Preferably, the well-washing operation in the sand-free concrete pipe body specifically includes:
[0033] The process involves injecting clean water into the sand-free concrete pipe and cyclically pumping and injecting water until clean water is drawn out of the sand-free concrete pipe.
[0034] Before the well washing operation is completed, the depth inside the sand-free concrete pipe is measured and the sediment at the bottom of the well is cleaned to ensure that the sediment at the bottom of the well is less than 0.3m.
[0035] The technical solution of the present invention has the following significant beneficial effects:
[0036] 1. In this application, the dewatering wells within the foundation pit are entirely located below the base elevation. A horizontally extending trench and channels are constructed below the base elevation. A sand-free concrete pipe is installed within the channels to form a dewatering well pipe. Pumping equipment is then installed within the sand-free concrete pipe, and a water intake pipe is laid in the trench, allowing water to drain from the dewatering well pipe. Since the foundation raft and foundation cushion are constructed above the base elevation, the dewatering wells within the foundation pit do not penetrate the foundation raft and foundation cushion. Therefore, the foundation raft and foundation cushion can effectively maintain their integrity and will not pose a risk of leakage. Furthermore, the upper part of the concrete pipe and the three openings can be directly sealed with concrete, which is convenient, quick, and cost-effective.
[0037] 2. The dewatering wells and construction methods in the foundation pit described in this application can be used in situations where the groundwater level is high, the rainfall is large, and the waterproofing level of the basement is high. This can reduce the risk of leakage in the foundation raft and foundation cushion, facilitate construction, and save costs.
[0038] Specific embodiments of the invention are disclosed in detail below with reference to the description and accompanying drawings, indicating how the principles of the invention can be employed. It should be understood that the embodiments of the invention are not therefore limited in scope. Features described and / or shown for one embodiment may be used in the same or similar manner in one or more other embodiments, combined with features in other embodiments, or substituted for features in other embodiments. Attached Figure Description
[0039] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of the invention in any way. Furthermore, the shapes and proportions of the components in the drawings are merely illustrative to aid in understanding the invention and do not specifically limit the shapes and proportions of the components. Those skilled in the art, guided by the teachings of this invention, can select various possible shapes and proportions to implement the invention according to specific circumstances.
[0040] Figure 1 This is a schematic diagram of the structure of the dewatering well in the foundation pit in an embodiment of the present invention.
[0041] The reference numerals in the above figures are as follows:
[0042] 1. Base elevation; 2. Trench; 3. Opening; 4. Channel; 5. Sand-free concrete pipe; 6. Water intake pipe; 7. First crushed stone; 8. Nylon filter screen; 9. Second crushed stone; 10. Third crushed stone; 11. Fine sand; 12. Concrete. Detailed Implementation
[0043] The details of the present invention can be more clearly understood by referring to the accompanying drawings and the description of specific embodiments. However, the specific embodiments of the present invention described herein are for illustrative purposes only and should not be construed as limiting the invention in any way. Under the teachings of this invention, those skilled in the art can conceive of any possible modifications based on the invention, all of which should be considered within the scope of the invention. It should be noted that when an element is referred to as being "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or there may be an intervening element. The terms "mounted," "connected," and "connected" should be interpreted broadly, for example, they can refer to mechanical or electrical connections, or internal communication between two elements, and can be direct or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only embodiments.
[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.
[0045] In order to improve the integrity of the foundation raft slab and reduce the possibility of leakage, this application proposes a dewatering well within the foundation pit. Figure 1 This is a schematic diagram of the structure of the dewatering well within the foundation pit in an embodiment of the present invention, as shown below. Figure 1 As shown, the dewatering well in the foundation pit may include: a base located in the foundation pit, a channel 4, a sand-free concrete pipe 5, a pumping device, and a water intake pipe 6, etc.
[0046] The base can be understood as the area located below the concrete cushion layer and foundation raft slab that are poured later during the excavation of the foundation pit.
[0047] A horizontally extending trench 2 and opening 3 are formed at a height below the base elevation. The trench 2 needs to have a certain depth to ensure that the water intake pipe 6, which will be laid in the trench 2 later, is located 50 mm below the base elevation. The base elevation is the junction height between the base and the concrete cushion layer, foundation raft, etc. The size and position of the opening 3 correspond to the channel 4. Alternatively, the dewatering well in the pit may include a concrete cushion layer, which is poured above the base, i.e., above the base elevation. The later foundation raft is also located above the base.
[0048] The channel 4 is vertically formed within the foundation pit. The channel 4 is below the base elevation and corresponds to the position of the opening 3.
[0049] A sand-free concrete pipe body 5 is installed in the channel 4. Multiple sand-free concrete pipe bodies 5 can be installed in the channel 4; for example, each sand-free concrete pipe body 5 can be 1000mm long, and multiple sand-free concrete pipe bodies 5 are spliced together to form a dewatering well pipe. Because the dewatering well pipe uses a sand-free concrete pipe body 5, water outside the pipe can slowly enter the pipe body through the side wall of the sand-free concrete pipe body 5. During this process, the pipe body can perform a coarse filtration function on the water entering the pipe body. Furthermore, the wall thickness of the sand-free concrete pipe body 5 can reach 50mm, which not only gives it sufficient strength but also sufficient coarse filtration performance.
[0050] To further enhance the filtration effect of the pipe body on the water entering the pipe body, the drainage well in the foundation pit may include a nylon filter screen 8. The nylon filter screen 8 is installed on the outer wall of the sand-free concrete pipe body 5. The mesh size of the nylon filter screen 8 can be selected between 100 and 150 mesh. The nylon filter screen 8 has strong acid and alkali resistance, corrosion resistance, and impact resistance, and can remain on the outside of the sand-free concrete pipe body 5. The nylon filter screen 8 mainly functions as a filter, effectively preventing filter mud, sand, and other substances in rainwater from clogging the water intake pipe 6.
[0051] The pumping equipment is installed inside the sand-free concrete pipe body 5. The pumping equipment is located in the lower part of the sand-free concrete pipe body 5, generally about 1m to 2m from the bottom of the dewatering well pipe. One end of the water-drawing pipe 6 is connected to the outlet of the pumping equipment, and the other end of the water-drawing pipe 6 extends upwards, bends at the opening 3, and is laid in the trench 2. After the water-drawing pipe 6 is laid in the trench 2, the trench 2 can be filled with first-grade gravel 7 to fix and protect the water-drawing pipe 6.
[0052] Alternatively, the trench 2 can extend all the way to the foundation pit trough, so that the water intake pipe 6 can be led through the foundation pit trough to the drainage network outside the foundation pit.
[0053] To fix and limit the sand-free concrete pipe body 5, a second type of crushed stone 9 can be filled between the channel 4 and the sand-free concrete pipe body 5. Alternatively, the particle size of the second type of crushed stone 9 can be between 2mm and 4mm. The second type of crushed stone 9 can protect the dewatering well pipe formed by the sand-free concrete pipe body 5 from external impacts, such as the crushing of heavy objects and construction loads. The second type of crushed stone 9 increases the supporting force of the pipe body, improving its stability and safety. Since the gap between the outer wall of the dewatering well pipe and the well hole is small, selecting crushed stone with a smaller particle size can effectively fill the gap densely. Furthermore, the underground environment mainly consists of soil, sand, and other materials with small particle sizes; small-diameter crushed stone can provide good filtration.
[0054] The sand-free concrete pipe body 5 is filled with third crushed stone 10. The particle size of the third crushed stone 10 is between 15mm and 30mm. The third crushed stone 10 can be filled up to about 400mm below the wellhead, after which a certain thickness of fine sand 11 is filled, for example, up to 100mm thick. The third crushed stone 10 and fine sand 11 need to be filled as densely as possible to prevent subsidence later. Due to the large pores inside the dewatering well pipe, larger particle size crushed stone is selected because it has greater strength, which can effectively prevent the dewatering well pipe from being crushed during later construction processes such as the foundation raft slab. The fine sand 11 has good sealing properties and can fill the tiny gaps in the crushed stone, improving the sealing performance of the seal.
[0055] The upper part of the concrete pipe and the opening 3 are sealed with concrete 12. Simultaneously, the water intake pipe 6 passes through the sealed concrete 12. The concrete 12 can be poured on top of the fine sand 11. The fine sand 11 isolates the concrete 12 from the third aggregate 10, preventing concrete mortar from flowing into the third aggregate 10, causing blockage and preventing water absorption. The concrete has good sealing properties, is easy to construct and operate, and can prevent air leakage inside the dewatering well pipe, ensuring its effective water absorption. The concrete 12 poured at the wellhead has a certain strength, which can prevent the risk of damage to the well wall and water intake pipe 6 caused by subsequent foundation raft construction, reducing subsequent maintenance costs.
[0056] This application also proposes a construction method for a dewatering well within a foundation pit. This construction method is applicable to the aforementioned dewatering wells within the foundation pit.
[0057] The construction method for the dewatering well within the foundation pit includes the following steps:
[0058] Drilling machinery is used to drill holes at the base of the pit to form channel 4.
[0059] In this step, a 600mm diameter reverse circulation drilling rig can be used to excavate the duct 4, which can ensure that the thickness of the sediment at the bottom of the well is no more than 20cm.
[0060] The sand-free concrete pipe body 5 is lowered into the channel 4 until it reaches the base elevation.
[0061] In this step, Ф400 sand-free concrete pipes 5 can be lowered one by one into the channel 4, and multiple sand-free concrete pipes 5 can be spliced together to form a dewatering well pipe until the base elevation is reached.
[0062] As a feasible option, during the process of lowering the sand-free concrete pipe 5 into the channel 4, a layer of nylon filter screen 8 can be wrapped around the outside of the sand-free concrete pipe 5.
[0063] A second type of crushed stone 9 is filled between the sand-free concrete pipe 5 and the channel 4. The second type of crushed stone 9 can be filled up to near the base elevation.
[0064] After the second crushed stone 9 is filled, the inside of the sand-free concrete pipe 5 is washed to remove the debris from the lower part of the sand-free concrete pipe 5.
[0065] In this step, clean water can be injected into the sand-free concrete pipe 5, and pumping and injection operations can be performed in a cyclical manner until clean water is drawn out of the sand-free concrete pipe 5. Before the well washing operation is completed, the depth inside the sand-free concrete pipe 5 is measured and the sediment at the bottom of the well is cleaned to ensure that the sediment at the bottom of the well is less than 0.3m.
[0066] After the well-washing operation is completed, a pumping device connected to a water intake pipe 6 is lowered into the sand-free concrete pipe body 5. The pumping device is lowered to a distance of about 1m to 2m from the bottom of the well.
[0067] After the groundwater level in the foundation pit meets the design requirements, the foundation pit is excavated. When the foundation pit is excavated to the designed elevation of the base, the sand-free concrete pipe 5 that is higher than the base elevation is cut off, and a trench 2 extending horizontally into the foundation pit is excavated below the base. The size of the trench 2 can be approximately 100mm*100mm, which can fully ensure the smooth laying of the water intake pipe 6.
[0068] The water pipe 6 is laid along the trench 2 into the foundation pit and connected to the drainage network outside the foundation pit.
[0069] In this step, the water intake pipe 6 should be laid as close as possible to 50mm below the soil surface at the base elevation, which will allow for effective protection of the water intake pipe 6 later. During the laying process through the trench 2 into the foundation pit trench, the direction of the water intake pipe 6 should be considered to reach the foundation pit trench in the shortest possible distance. When passing under-column piers or sump pits, it should be avoided as much as possible. When crossing unavoidable areas such as post-cast strips, ensure that the water intake pipe 6 is 50mm below the soil surface at the base elevation.
[0070] After the water pipe 6 is laid, the third gravel 10 is filled into the sandless concrete pipe body 5 until the upper part of the sandless concrete pipe body 5 is filled with fine sand 11, and then concrete 12 is poured up to the base elevation 1.
[0071] In this step, the third type of crushed stone 10 and fine sand 11 need to be compacted to prevent settling, and the poured concrete 12 can directly abut against the fine sand 11. C15 concrete can be used for the poured concrete 12.
[0072] The trench 2 is filled with crushed stone and compacted. Then, a concrete cushion layer is poured on the base in the pit. Subsequently, waterproofing and foundation raft construction are carried out normally.
[0073] In this application, the dewatering wells within the foundation pit are entirely located below the base elevation. A horizontally extending trench 2 and channel 4 are constructed below the base elevation. A sand-free concrete pipe 5 is installed within the channel 4 to form a dewatering well pipe. Pumping equipment is then placed inside the sand-free concrete pipe 5, and a water intake pipe 6 is laid in the trench 2, allowing water to drain from the dewatering well pipe. Since the foundation raft and foundation cushion are constructed above the base elevation, the dewatering wells within the foundation pit do not penetrate the foundation raft and foundation cushion. Therefore, the foundation raft and foundation cushion can effectively maintain their integrity and will not pose a risk of leakage. Furthermore, the upper part of the concrete pipe and the opening 3 can be directly sealed with concrete, which is convenient, quick, and cost-effective.
[0074] The dewatering wells and construction methods described in this application can be used in situations with high groundwater levels, large rainfall, and high basement waterproofing levels. They can reduce the risk of leakage in the foundation raft and foundation pad, facilitate construction, and save costs.
[0075] All articles and references disclosed herein, including patent applications and publications, are incorporated herein by reference for various purposes. The term “substantially constitutes…” used to describe a combination should include the identified element, component, part, or step, as well as other elements, components, parts, or steps that do not substantially affect the essential novelty of the combination. The use of the terms “comprising” or “including” to describe combinations of elements, components, parts, or steps herein also contemplates embodiments substantially constituted by such elements, components, parts, or steps. The use of the term “may” herein is intended to indicate that any described attribute “may” include is optional. Multiple elements, components, parts, or steps can be provided by a single integrated element, component, part, or step. Alternatively, a single integrated element, component, part, or step can be divided into multiple separate elements, components, parts, or steps. The disclosure of “a” or “an” used to describe an element, component, part, or step does not imply exclusion of other elements, components, parts, or steps.
[0076] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the scope of protection of the present invention.
Claims
1. A dewatering well within a foundation pit, characterized by, The dewatering well in the foundation pit comprises: a base in the foundation pit, a trench and an opening being formed in the base at a height below the base level and extending horizontally; a hole being formed in the foundation pit vertically below the base level and corresponding to the position of the opening; a sandless concrete pipe being arranged in the hole; a water pumping device being arranged in the sandless concrete pipe; a water suction pipe, one end of the water suction pipe being connected to the outlet of the water pumping device, the other end of the water suction pipe extending upward through the opening, bending and being laid in the trench, and the upper part of the concrete pipe and the opening being sealed by concrete.
2. A dewatering well within a foundation pit according to claim 1, characterised in that, The trench is filled with first gravel; the dewatering well in the foundation pit comprises: a concrete cushion being cast on the base.
3. The dewatering well within a foundation pit according to claim 1, wherein, The dewatering well in the foundation pit further comprises: a nylon filter screen being arranged on the outer wall of the sandless concrete pipe.
4. A dewatering well in a foundation pit according to claim 3, c h a r a c t e r i s e d in that The mesh number of the nylon filter screen is between 100 and 150.
5. The dewatering well within a foundation pit according to claim 1, wherein, The hole and the sandless concrete pipe are filled with second gravel, the particle size of the second gravel being between 2mm and 4mm.
6. The dewatering well within a foundation pit according to claim 1, wherein, The sandless concrete pipe is filled with third gravel, the particle size of the third gravel being between 15mm and 30mm.
7. A dewatering well in a foundation pit according to claim 6, c h a r a c t e r i s e d in that The upper part of the concrete pipe for sealing is filled with fine sand between the concrete and the third gravel.
8. The dewatering well within a foundation pit according to claim 1, wherein, The trench extends to the foundation pit trench, so that the water suction pipe is led to the drainage pipe network outside the foundation pit through the foundation pit trench.
9. A method of constructing a dewatering well in a foundation pit, characterized by, The construction method of the dewatering well in the foundation pit comprises the following steps: drilling a hole in the base of the foundation pit by using a drilling machine to form a hole; lowering a sandless concrete pipe in the hole until the base level is reached; filling the second gravel between the sandless concrete pipe and the hole; after filling the second gravel, performing a well washing operation in the sandless concrete pipe; after the well washing operation is completed, lowering the water pumping device connected with the water suction pipe into the sandless concrete pipe; excavating the foundation pit, when the foundation pit is excavated to the designed level of the base, cutting off the sandless concrete pipe above the base level in the foundation pit, and excavating a trench extending horizontally below the base to the foundation pit trench; laying the water suction pipe along the trench into the foundation pit trench and connecting to the drainage pipe network outside the foundation pit; after the water suction pipe is laid, filling the third gravel in the sandless concrete pipe until the upper part of the sandless concrete pipe is filled with fine sand, and then casting concrete to the level of the base; filling the trench with gravel, and then casting a concrete cushion on the base in the foundation pit, and then normally performing waterproofing and foundation raft construction.
10. The method of claim 9, wherein, In the step of performing a well washing operation in the sandless concrete pipe, specifically comprising: injecting clean water into the sandless concrete pipe, and performing pumping and injection operations in a cycle until clean water is pumped out of the sandless concrete pipe; before the well washing operation is completed, measuring the depth of the sandless concrete pipe and cleaning the bottom deposits, so that the bottom deposits are less than 0.3m.