Deep foundation pit confined water dewatering well plugging method and system

Abstract

The invention relates to the technical field of deep foundation pit engineering, in particular to a deep foundation pit confined water precipitation well blocking method and system.The method comprises the following steps that after precipitation well construction is completed, a worker sleeves a water suction pump with a stainless steel protective cover, connects a precipitation pipe and then puts the water suction pump into the precipitation well for water pumping; a water intercepting ball valve is arranged at the top of the water suction pump; backfilling gravel aggregate to a position one meter away from the bottom of the water stop steel pipe sleeve to form a water seepage buffer layer; the clay layer is backfilled to the position of the water intercepting ball valve on the downcast pipe, and the downcast pipe is cut off above the water intercepting ball valve; 20 cm concrete (40 cm away from a well mouth) is backfilled, a water stop steel plate A is welded, and a waterproof coating is brushed on the top face of the water stop steel plate A; repeating S and welding the water stop steel plate B to form a double water stop structure. By means of the conical structure design of the water stop steel pipe sleeve, local stress concentration is reduced by increasing the contact face, and long-term stability and reliability of the plugging system when the plugging system bears underground water pressure are guaranteed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of deep foundation pit engineering, in particular to a deep foundation pit confined water dewatering well plugging method and system. BACKGROUND

[0002] The development of society cannot be separated from the construction of engineering infrastructure. In the current urban engineering construction, the development of space on the ground is limited, and the utilization of underground space is becoming more and more extensive. In the underground engineering construction, deep foundation pit construction is inevitably involved. As known, the main difficulty in deep foundation pit construction is the control of underground water, which requires dewatering operation during the construction of the foundation pit. In most cases, in order to meet the requirements of the construction site, the dewatering well needs to be plugged after the completion of the deep foundation pit bottom plate structure construction. In the case of the dewatering well penetrating through the cushion layer and the waterproof layer, the underground deep foundation pit structure has a high requirement for waterproofing. Therefore, the plugging of the dewatering well and the deep foundation pit bottom plate structure part has become an important problem in construction.

[0003] For the engineering with a large excavation depth, since such deep foundation pit engineering is mostly excavated to underground water, when the well is drilled for dewatering, the phenomenon of underground water generating pressure and surging upward through the dewatering well often occurs. Especially for the well drilled on the basement foundation raft, if the water pump is removed, the underground water will quickly gush out of the well mouth. Direct plugging is easy to cause the well mouth to spout due to the pressure of the confined water, which threatens the safety of construction. Single material plugging is easy to form a water seepage channel due to shrinkage cracks. The underground water pressure cannot be adjusted in real time during the plugging process.

[0004] Based on this, the present application discloses a deep foundation pit confined water dewatering well plugging method and system. SUMMARY

[0005] In order to solve the problems of the deep foundation pit engineering mostly excavated to underground water, the phenomenon of underground water generating pressure and surging upward through the dewatering well often occurs when the well is drilled for dewatering. Especially for the well drilled on the basement foundation raft, if the water pump is removed, the underground water will quickly gush out of the well mouth. Direct plugging is easy to cause the well mouth to spout due to the pressure of the confined water, which threatens the safety of construction. Single material plugging is easy to form a water seepage channel due to shrinkage cracks. The underground water pressure cannot be adjusted in real time during the plugging process, the present application provides a deep foundation pit confined water dewatering well plugging method and system, which comprises the following steps: S1, after the construction of the dewatering well is completed, a pre-buried water stop steel pipe sleeve is installed above the well mouth of the dewatering well; S2, the worker sets a stainless steel protective cover outside the water pump and connects the dewatering pipe, and then puts it into the dewatering well for water pumping. The top of the water pump is provided with a water stop ball valve; S3, backfill sand and gravel aggregate to the bottom of the waterproof steel pipe sleeve one meter, form a water seepage buffer layer; S4, backfill clay layer to the position of the water cut ball valve on the water cut ball valve, cut off the water pipe; S5, backfill 20cm concrete (distance from the wellhead 40cm), weld waterproof steel plate A, the top surface of the waterproof steel plate A is brushed with waterproof coating; S6, repeat S5 to weld waterproof steel plate B, form a double waterproof structure.

[0006] Preferably, the exposed part of the waterproof steel pipe sleeve is 5cm long, and the waterproof steel pipe sleeve is conical with a cone angle of °.

[0007] Preferably, the particle size of the sand and gravel aggregate used for filling is 5-10mm, and the thickness of the water seepage buffer layer is ≥1m, which is used to disperse water pressure and allow a small amount of water seepage.

[0008] Preferably, the concrete used for pouring has a strength of C30 and a slump of 160-180mm, which is used for main plugging and bearing water pressure.

[0009] Preferably, the water cut ball valve provided on the water pipe has a pressure resistance of ≥0.5MPa, which is used to actively control the size of water pressure during plugging.

[0010] Preferably, the thickness of the waterproof steel plate A and the waterproof steel plate B is 8mm.

[0011] Preferably, the material of the waterproof coating is polyurethane.

[0012] Preferably, the stainless steel protective cover is made of stainless steel.

[0013] Preferably, the thickness of the waterproof steel pipe sleeve is 6mm, and its length is ≥20cm.

[0014] Preferably, the top of the stainless steel protective cover is detachably connected with a detachable plate, and a plurality of filter holes are formed on the outer sides of the stainless steel protective cover and the detachable plate.

[0015] 1. In the deep foundation pit water pressure well plugging method and system, the conical structure design of the waterproof steel pipe sleeve can expand its contact area with the surrounding concrete, thereby effectively enhancing the anchoring force. During the embedding process, the inclined side wall of the waterproof steel pipe sleeve forms a larger friction contact surface with the concrete, and the conical tip helps to guide the concrete slurry to fully fill the gap between the structures and form a tighter mechanical interlocking. This design not only improves the overall anti-pulling performance of the structure, but also reduces local stress concentration by increasing the contact area, ensuring the long-term stability and reliability of the plugging system under the pressure of underground water.

[0016] 2、The water stop steel pipe sleeve and the raft main reinforcement are connected by full welding, the length of the welding seam is greater than or equal to 10 times the diameter of the steel bar, so that the two form an integral force structure, the axial stiffness of the water stop steel pipe sleeve and the transverse restraint force of the raft steel bar are coupled with each other after welding, a hoop restraint system similar to a stirrup is formed, radial deformation caused by groundwater pressure is effectively resisted, and the welded joint can still maintain stable mechanical properties under the double actions of concrete shrinkage and creep and groundwater corrosion. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 It is a schematic diagram of the overall construction section structure of the present application; Figure 2 It is a schematic diagram of the structure of the stainless steel protective cover of the present application; Figure 3 It is a schematic diagram of the structure of the water stop steel pipe sleeve of the present application Figure 4 It is a schematic diagram of the water inrush principle of the deep foundation pit dewatering well of the present application.

[0018] The meanings of the various reference numerals in the drawings are as follows: 1, dewatering well; 2, water stop steel pipe sleeve; 3, water pump; 4, stainless steel protective cover; 5, dewatering pipe; 6, sand and stone aggregate; 7, water seepage buffer layer; 8, clay layer; 9, water stop ball valve; 10, concrete; 11, water stop steel plate A; 12, water stop steel plate B; 13, waterproof coating; 14, dismounting plate; 15, filter hole. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0020] Therefore, the present application provides a deep foundation pit dewatering well plugging method and system, as shown in Figures 1-4 The method comprises the following steps: S1, after the construction of the dewatering well 1 is completed, a pre-buried water stop steel pipe sleeve 2 is installed above the well mouth of the dewatering well 1; S2, after the stainless steel protective cover 4 is set on the water pump 3 and connected with the dewatering pipe 5, the water pump 3 is put into the dewatering well 1 to pump water, and the top of the water pump 3 is provided with a water stop ball valve 9; S3, sand and stone aggregate 6 is backfilled to one meter below the water stop steel pipe sleeve 2 to form a water seepage buffer layer 7; S4, a clay layer 8 is backfilled to the position of the water stop ball valve 9 above the dewatering pipe 5, and the dewatering pipe 5 is cut off above the water stop ball valve 9. S5, backfill 20cm concrete 10 distance wellhead 40cm, welding water stop steel plate A11, water stop steel plate A11 top surface brush waterproof coating 13; S6, repeat S5 welding water stop steel plate B12, forming double water stop structure.

[0021] When working, the staff completes the construction of the dewatering well 1 through external tunneling equipment, installs the embedded water stop steel pipe sleeve 2 at the wellhead of the dewatering well 1, further sets the water pump 3 with a stainless steel protective cover 4, further connects the stainless steel protective cover 4 with the dewatering pipe 5, and puts it into the inside bottom of the dewatering well 1 to pump water. The top of the dewatering pipe 5 is provided with a water interception ball valve 9 for controlling the flow rate at the position of the wellhead of the dewatering well 1. When the water level inside the dewatering well 1 is pumped to a suitable position, the dewatering pipe 5 is cut off above the water interception ball valve 9 by backfilling to the position one meter below the embedded water stop steel pipe sleeve 2, and further backfilling the clay layer 8 to the position of the water interception ball valve 9. When the dewatering pipe 5 is cut off, 20cm-thick concrete 10 is backfilled. At this time, the backfilled concrete 10 is 40cm away from the wellhead. After the concrete 10 is backfilled, the water stop steel plate A11 is welded, and at the same time, the water stop steel plate A11 is brushed with a waterproof coating 13. Then, the concrete 10 is further backfilled to the position of the wellhead, and the water stop steel plate B12 is welded. After the water stop steel plate B12 is welded, the water stop steel plate B12 is brushed with a waterproof coating 13.

[0022] By embedding the steel sleeve and layering the plugging, the pressure-bearing water gushing path is effectively blocked, the valve controls the dewatering and the plugging to be performed synchronously, the construction risk is reduced, the multi-water-stop-structure steel plate + waterproof coating improves the long-term waterproof reliability, The exposed part of the water stop steel pipe sleeve 2 has a length of 5cm. The water stop steel pipe sleeve 2 is designed in a conical shape with a conical angle of 30°. The thickness of the water stop steel pipe sleeve 2 is 6mm, and the length is greater than or equal to 20cm. Through the design of the structure of the stainless steel protective cover 4, the first water stop barrier of the dewatering well 1 is formed, and the anchoring force is enhanced.

[0023] The contact area with the surrounding concrete can be enlarged, so that the anchoring force is effectively enhanced. During embedding, the oblique side wall of the water stop steel pipe sleeve 2 forms a larger friction contact surface with the concrete 10. At the same time, the conical tip helps to guide the concrete 10 slurry to fully fill the structural gap, forming a more compact mechanical interlocking. This design not only improves the overall anti-pulling performance of the structure, but also reduces local stress concentration by increasing the contact area, ensuring the long-term stability and reliability of the plugging system when bearing the underground water pressure.

[0024] By embedding the water stop steel pipe sleeve 2 and layering the plugging, the pressure-bearing water gushing path is effectively blocked, and the success rate of plugging is greater than or equal to 95%.

[0025] The water stop ball valve 9 controls the synchronous precipitation and plugging, the water pressure gradient changes ≤0.1 MPa / m, and the underground water pressure can be adjusted in real time during the plugging process.

[0026] The sand and gravel aggregate 6 used for filling has a particle size of 5-10 mm, and the water seepage buffer layer 7 is laid with a thickness of ≥1 m, which is used to disperse water pressure and allow a small amount of water seepage.

[0027] During operation, the water seepage buffer layer 7 can effectively control the speed of precipitation, avoid the erosion of concrete 10, slow down the speed of precipitation, protect the poured concrete 10, and improve the use strength and service life of the concrete 10.

[0028] The concrete 10 used for pouring has a strength of C30 and a slump of 160-180 mm, which is used for main plugging and withstands water pressure.

[0029] The water stop ball valve 9 provided on the precipitation pipe 5 has a pressure resistance of ≥0.5 MPa, which is used to actively control the water pressure during the plugging process.

[0030] The water stop steel plate A11 and the water stop steel plate B12 have a thickness of 8 mm.

[0031] The waterproof coating 13 is made of polyurethane.

[0032] During operation, the concrete 10, the water stop steel plate A11 and the water stop steel plate B12 form a double water stop structure, the shear resistance of the double steel plates is improved, and the long-term waterproof reliability is improved.

[0033] Multiple materials reduce the formation of water seepage channels caused by shrinkage cracks and reduce the risk of water leakage.

[0034] The rigid water stop ring tightly combines the steel sleeve and the raft concrete through a welding joint, completely blocking the seepage path of the pressure water along the contact surface of the sleeve and the concrete. The leakage amount of this structure under 0.3 MPa water pressure is reduced by more than 90% compared to the traditional anchoring method.

[0035] The welding process uses a layered welding method to first spot weld and then full weld to form, avoiding the influence of thermal deformation on the perpendicularity of the sleeve. At the same time, by embedding a positioning fixture, the concentricity error between the steel sleeve and the steel bar is ≤2 mm, providing a precise reference for the subsequent plugging process.

[0036] The welding joint of the rigid water stop ring uses an E43-type welding rod with a tensile strength of ≥420 MPa, which matches the material of the steel sleeve. Under the dual action of concrete shrinkage and creep and groundwater corrosion, the welding joint can still maintain stable mechanical properties, and the design life is the same as the main structure.

[0037] The stainless steel protective cover 4 is made of stainless steel, which can be used for a long time in a humid environment, improving its service life and use effect.

[0038] The top of the stainless steel protective cover 4 is detachably connected with a detachable plate 14, and a plurality of filter holes 15 are formed on the outer side of the stainless steel protective cover 4 and the detachable plate 14.

[0039] The detachable plate 14 is convenient for installation of the water pump 3, and the filter holes 15 are convenient for water flow and slow down the influence of sand and gravel on the water pump 3, thereby further improving the service life and use effect of the water pump 3. It should be noted that the relational terms herein such as first and second and the like are used solely to distinguish one entity or action from another, without necessarily requiring or implying any such actual relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0040] Although embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, alternatives, and variations can be made in the embodiments without departing from the spirit and scope of the present application as defined by the appended claims and their equivalents.

Claims

1. A method and system for plugging a deep foundation pit confined water dewatering well, characterized in that: In the construction of a dewatering well in a deep foundation pit, the following steps are included: S1, after the construction of the dewatering well (1) is completed, a pre-buried water stop steel pipe sleeve (2) is installed above the well mouth of the dewatering well (1); S2, the staff sets a stainless steel protective cover (4) outside the water pump (3) and connects the dewatering pipe (5), then puts it into the dewatering well (1) for pumping, and the top of the water pump (3) is provided with a water stop ball valve (9); S3, backfilling sand and gravel aggregate (6) to one meter below the bottom of the water stop steel pipe sleeve (2) forms a water seepage buffer layer (7); S4, backfilling clay layer (8) to the position of the water stop ball valve (9) on the dewatering pipe (5), cutting off the dewatering pipe (5) above the water stop ball valve (9); S5, backfilling 20cm of concrete (10) (40cm from the well mouth), welding a water stop steel plate A (11), and brushing a waterproof coating (13) on the top surface of the water stop steel plate A (11); S6, repeating S5 to weld a water stop steel plate B (12) to form a double water stop structure.

2. The method and system for plugging a deep foundation pit confined water dewatering well according to claim 1, characterized in that: The exposed part of the water stop steel pipe sleeve (2) has a length of 5cm, and the water stop steel pipe sleeve (2) is designed in a conical shape with a taper angle of 30°.

3. The method and system for plugging a deep foundation pit confined water dewatering well according to claim 1, characterized in that: The sand and gravel aggregate (6) used for filling has a particle size of 5-10mm, and the water seepage buffer layer (7) has a laying thickness of ≥1m for dispersing water pressure and allowing a small amount of water seepage.

4. The method and system for plugging a deep foundation pit confined water dewatering well according to claim 1, characterized in that: The concrete (10) used for pouring has a strength of C30 and a slump of 160-180mm for main blocking and bearing water pressure.

5. The method and system for plugging a deep foundation pit confined water dewatering well according to claim 1, characterized in that: The water stop ball valve (9) provided on the dewatering pipe (5) has a pressure resistance of ≥0.5MPa for actively controlling the water pressure in the blocking process.

6. The method and system for plugging a deep foundation pit artesian water dewatering well according to claim 1, characterized in that: The water stop steel plate A (11) and the water stop steel plate B (12) have a thickness of 8mm.

7. The method and system for plugging a deep foundation pit artesian water dewatering well according to claim 1, characterized in that: The waterproof coating (13) is made of polyurethane.

8. The method and system for plugging a deep foundation pit artesian water dewatering well according to claim 1, characterized in that: The stainless steel protective cover (4) is made of stainless steel.

9. The method and system for plugging a deep foundation pit artesian water dewatering well according to claim 2, characterized in that: The water stop steel pipe sleeve (2) has a thickness of 6mm and a length of ≥20cm.

10. The method and system for plugging a deep foundation pit confined water dewatering well according to claim 1, characterized in that: The top of the stainless steel protective cover (4) is detachably connected with a detachable plate (14), and a plurality of filter holes (15) are formed on the outer sides of the stainless steel protective cover (4) and the detachable plate (14).

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