Composite well sealing method for ultra-deep foundation pit drainage well

Abstract

The invention relates to the field of keeping an underground foundation section or other areas dry by lowering the underground water level, in particular to a composite well sealing method for an ultra-deep foundation pit drainage well. The composite well sealing method for the ultra-deep foundation pit drainage well is implemented according to the following steps that firstly, an overall underground structure cushion layer is constructed; 2, acrylic acid waterproof construction of the drainage well; thirdly, a drainage well waterproof protection layer is constructed; fourthly, the drainage well is filled with graded gravel; fifthly, concrete with the same mark number as the raft plate is poured in a layered mode; sixthly, the opening of the steel sleeve is filled with water stopping glue which swells slowly when meeting water; 7, covering the opening part of the steel sleeve with a steel cover plate, and performing angle welding; 8, acrylic acid is laid for waterproofing; and ninthly, raft plate construction is conducted. The manufacturing cost is reduced, and the waterproof performance is improved.

Description

Technical Field

[0001] The invention relates to the field of keeping underground foundation sections or other areas dry by lowering groundwater levels, and in particular to a composite well sealing method for an ultra-deep foundation pit dewatering well. Background Art

[0002] In traditional drainage well plugging methods, such as concrete plugging method and cement mortar plugging method, plugging is often chosen after the main structure raft slab is cast, and the waterproof membrane used is also ordinary membrane. However, this plugging method has obvious disadvantages. Because the water pressure in the drainage well is too high, and the external pressure is relatively smaller than the pressure in the well, this pressure difference becomes a potential hidden danger, and the ordinary waterproof membrane has poor adhesion and waterproof performance and a short service life. When the wellhead is not completely plugged, it is easy to cause serious leakage problems. This leakage will not only have a direct impact on the quality and progress of the project, but may also lead to a series of subsequent troubles. Once leakage occurs, groundwater will continue to flow into the construction area, which will not only increase the difficulty of construction, but also the leaked water may erode the completed main structure, affecting its stability and durability, and burying quality risks for the long-term use of the project.

[0003] There are currently two main methods to solve the leakage of drainage wells. One is to optimize the performance of the plugging material itself. The disadvantage is that the cost becomes higher and the stability is uncertain. The other is to use layered plugging and gradual pressurization to make the plugging material fully fill the space in the well and reduce the generation of voids and cracks. The disadvantage is that the voids and cracks cannot be absolutely eliminated, there is still a risk of leakage, and the construction difficulty is relatively large. Summary of the invention

[0004] In order to overcome the defects of the prior art and provide a foundation pit construction method which reduces construction cost, shortens construction period and improves waterproof performance, the present invention discloses a composite well sealing method for an ultra-deep foundation pit dewatering well.

[0005] The present invention achieves the purpose of the invention through the following technical solutions: A composite sealing method for an ultra-deep foundation pit dewatering well is implemented in the following steps: Step 1: Construction of the overall underground structure cushion layer: Clean the base layer and place the steel sleeve at the wellhead to fix it firmly; clean the debris and dust on the surface of the base layer to ensure that the base layer is flat and solid, and sprinkle water to moisten it before pouring the concrete cushion layer. Fix the steel casing during pouring and do not allow it to deviate; the surface of the concrete cushion layer must be flat and free of debris to ensure the quality of the later waterproofing construction and eliminate the risk of leakage; Step 2: Construction of acrylic waterproofing for drainage wells: Strengthen the treatment of the corners and the joints of the pipe roots. After the first coat of paint is dry, apply the second coat in a direction perpendicular to the first coat to ensure the thickness and uniformity of the coating. Each layer of waterproofing needs to be turned up to the bottom edge of the steel sleeve water-stop steel plate; Step 3: Construction of waterproof protective layer for drainage well: Clean the acrylic waterproof surface and lay a waterproof protective layer to prevent the acrylic waterproof from causing damage when pouring the protective layer; pour the concrete protective layer; Step 4: Fill the drainage well with graded sand and gravel: Fill the drainage well with graded sand and gravel to below the mouth of the steel casing; Step 5: Pour concrete with the same grade as the raft slab in layers: After the graded sand and gravel is filled, the concrete with the same grade as the reinforced concrete raft is poured in layers on top, and vibrated and compacted with a vibrating rod, and poured to the upper end of the steel sleeve; Step 6: Fill the steel casing mouth with water-slow-expanding water-stop glue: Fill the mouth of the steel sleeve with water-slow-expanding water-stop glue; Step 7: Cover the steel cover plate to the mouth of the steel sleeve and perform fillet welding: Use a steel cover plate with a radius smaller than the mouth of the steel sleeve for fillet welding and plugging; Step 8: Laying acrylic waterproofing: Repeat step 2 to lay acrylic waterproofing and turn it down to the waterstop steel plate; Step 9: Raft construction: A waterproof protective layer is laid on the drainage well mouth to prevent damage to the acrylic waterproofing during pouring, and an acrylic waterproofing end is set between the waterproof protective layer and the acrylic waterproofing. When pouring the reinforced concrete raft slab, it is necessary to pour in layers and fully vibrate and compact the concrete around the drainage well so that the concrete fully wraps the well mouth.

[0006] The composite sealing method for the ultra-deep foundation pit drainage well is characterized by: in step 2, the waterproof coating is applied with a brush, a roller brush or a spray gun, etc., starting from one end, and the waterproof coating is evenly applied with a uniform thickness without any leakage; the coating is applied vertically first, and then horizontally, to ensure that the coating covers the entire surface; The composite sealing method for ultra-deep foundation pit drainage well is characterized in that: in step three, the concrete protective layer is cast with 50 thick C20 fine stone; The composite sealing method for ultra-deep foundation pit drainage well is characterized by: in step 4, filling to 620mm below the mouth of the steel casing; The composite sealing method for ultra-deep foundation pit dewatering wells is characterized in that: in step seven, the radius of the steel cover plate is 10 mm smaller than the mouth of the steel sleeve (2).

[0007] The present invention discloses a composite sealing method for ultra-deep foundation pit drainage wells, which reduces leakage caused by excessive water pressure in the well and incomplete wellhead sealing in traditional drainage and plugging methods. The present invention is improved based on the previous technical construction, and the conventional construction main structure raft is sealed in advance after the casting is completed, so that the leakage risk of the drainage well is greatly reduced.

[0008] The present invention has the following beneficial effects: Beneficial Effects

[0009] Existing technology: Concrete plugging method: first drain the water in the well, clean up the debris at the bottom of the well, then lay a layer of gravel or sand at the bottom of the well as a cushion, and then pour concrete to the wellhead. This method is not only expensive, but also has obvious cracks at the junction of concrete and the well wall. When the water pressure in the well is too high, the hidden danger of water seepage is very serious.

[0010] The composite well sealing method of the present invention forms a new well sealing method by combining multiple anti-leakage measures such as acrylic waterproofing, raft slabs, graded sand and gravel and concrete backfill, steel sleeves, and water-slow-expanding water-stopping glue. This method can not only solve the problems of leakage caused by high water pressure, poor materials, and construction difficulties, but also reduces the construction cost, simplifies the construction, and greatly shortens the construction period.

[0011] In order to solve the problem of drainage well leakage caused by excessive water pressure, the present invention changes the drainage well from being blocked on the raft to being blocked under the raft in the new method, and the pressure inside and outside the well is kept stable through the pressure of the raft itself and the wrapping of the wellhead; acrylic waterproofing is used to make up for the problems of poor waterproof performance and short service life of waterproof materials in the old method, and graded sand and gravel backfilling can reduce the construction cost and shorten the construction period. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a construction schematic diagram of the present invention, Figure 2 It is a schematic diagram of the steel sleeve and the steel cover plate in the present invention. DETAILED DESCRIPTION

[0013] The present invention is further described below by means of specific examples. Example

[0014] A composite sealing method for ultra-deep foundation pit dewatering wells, such as Figure 1 and Figure 2 As shown, follow the steps below: Step 1: Construction of the overall underground structure cushion layer: Clean the base layer, place the steel sleeve 2 at the wellhead and fix it firmly; clean the debris and dust on the surface of the base layer, ensure that the base layer is flat and solid, and sprinkle water to moisten it, then pour the concrete cushion layer 8, fix the steel casing 2 during pouring and do not deviate; the surface of the concrete cushion layer 3 must be flat and free of debris to ensure the quality of the later waterproof construction and eliminate the hidden danger of leakage; Step 2: Construction of acrylic waterproofing for drainage wells: Strengthen the corners and the joints of the pipe roots, and then apply the waterproof coating. Use a brush, roller brush or spray gun to evenly apply the waterproof coating from one end. The thickness should be uniform and there should be no missing parts. Generally, apply vertically first and then horizontally to ensure that the coating covers the entire surface. After the first coat of coating dries (usually takes several hours, depending on the product instructions and environmental conditions), apply the second coat in a direction perpendicular to the first coat to ensure the thickness and uniformity of the coating. Each layer of waterproofing needs to be turned up to the lower edge of the water-stop steel plate of the steel sleeve 2. Step 3: Construction of waterproof protective layer for drainage well: Clean the surface of acrylic waterproofing 4, lay waterproofing protective layer 7 to prevent the acrylic waterproofing 4 from causing damage when pouring the protective layer; pour a 50mm thick C20 fine stone concrete protective layer; Step 4: Fill the drainage well with graded sand and gravel: The dewatering well is filled with graded gravel 10 to 620 mm below the second end of the steel casing. The advantage of using graded gravel is that after compaction, a relatively stable structure can be formed, the cost is relatively economical, the construction process is relatively simple, and it is easy to operate and control the construction quality. Step 5: Pour concrete with the same grade as the raft slab in layers: After the graded sand and gravel 10 is filled, the concrete 9 with the same grade as the reinforced concrete raft 6 is poured in layers on top, and vibrated and compacted with a vibrating rod, and poured to the upper opening of the steel sleeve 2; Step 6: Fill the steel casing mouth with water-slow-expanding water-stop glue: Fill the two openings of the steel sleeve with water-slow expansion waterproofing glue. The advantage of using water-slow expansion waterproofing glue is that it can expand rapidly when it comes into contact with water, effectively blocking the gap and preventing water penetration, and can be tightly bonded with a variety of materials to form a good sealing effect; Step 7: Cover the steel cover plate to the mouth of the steel sleeve and perform fillet welding: A steel cover plate 3 with a radius smaller than 10 mm of the mouth of the steel sleeve 2 is used for fillet welding 5 for sealing. The fillet welding 5 can effectively connect the two welds together, provide sufficient strength to withstand various loads, and is simple to operate and fast in construction. Step 8: Laying acrylic waterproofing: Repeat step 2 to lay acrylic waterproofing 4, and turn it down to the water-stop steel plate; Step 9: Raft construction: A waterproof protective layer 7 is laid on the drainage well mouth to prevent damage to the acrylic waterproof 4 during pouring, and an acrylic waterproof end 1 is arranged between the waterproof protective layer 7 and the acrylic waterproof 4; when pouring the reinforced concrete raft 6, it is necessary to pour in layers and fully vibrate and compact the concrete around the drainage well so that the concrete fully wraps the well mouth.

Claims

1. A composite sealing method for ultra-deep foundation pit dewatering wells, which is implemented in the following steps: Step 1: Construction of the overall underground structure cushion layer: Clean the base layer, place the steel sleeve (2) at the wellhead and fix it firmly; clean the debris and dust on the surface of the base layer, ensure that the base layer is flat and solid, and sprinkle water to moisten it, then pour the concrete cushion layer (8), and fix the steel sleeve (2) during pouring to prevent it from shifting; the surface of the concrete cushion layer (3) must be flat and free of debris to ensure the quality of the later waterproof construction and eliminate the hidden danger of leakage; Step 2: Construction of acrylic waterproofing for drainage wells: Strengthen the treatment of the corners and the joints of the pipe roots. After the first coat of paint is dry, apply the second coat in a direction perpendicular to the first coat to ensure the thickness and uniformity of the coating. Each layer of waterproofing needs to be turned up to the lower edge of the water-stop steel plate of the steel sleeve (2); Step 3: Construction of waterproof protective layer for drainage well: Clean the surface of the acrylic waterproofing (4), lay a waterproofing protective layer (7) to prevent the acrylic waterproofing (4) from being damaged when pouring the protective layer; pour the concrete protective layer; Step 4: Fill the drainage well with graded sand and gravel: Filling the drainage well with graded sand and gravel (10) to below the mouth of the steel casing (2); Step 5: Pour concrete with the same grade as the raft slab in layers: After the graded sand and gravel (10) is filled, concrete (9) with the same grade as the reinforced concrete raft (6) is poured in layers on top, and vibrated and compacted with a vibrating rod, and poured to the upper opening of the steel sleeve (2); Step 6: Fill the steel casing mouth with water-slow-expanding water-stop glue: Fill the mouth of the steel sleeve (2) with a water-slow swelling waterproof glue; Step 7: Cover the steel cover plate to the mouth of the steel sleeve and perform fillet welding: A steel cover plate (3) having a radius smaller than that of the mouth of the steel sleeve (2) is used for fillet welding (5) for sealing; Step 8: Laying acrylic waterproofing: Repeat step 2 to lay acrylic waterproofing (4) and then turn it down to the water-stop steel plate; Step 9: Raft construction: A waterproof protective layer (7) is laid on the drainage well mouth to prevent the acrylic waterproof (4) from being damaged during pouring, and an acrylic waterproof end (1) is arranged between the waterproof protective layer (7) and the acrylic waterproof (4); when pouring the reinforced concrete raft (6), it is necessary to pour in layers and fully vibrate and compact the concrete around the drainage well so that the concrete fully wraps the well mouth.

2. The composite sealing method for ultra-deep foundation pit dewatering well according to claim 1 is characterized by: In the second step, apply the waterproof coating with a brush, roller brush or spray gun, starting from one end, and evenly apply the waterproof coating. The thickness should be uniform and no gaps should be left. Apply vertically first, then horizontally to ensure full coverage of the coating.

3. The composite sealing method for ultra-deep foundation pit dewatering well according to claim 2 is characterized by: In step three, the concrete protective layer is cast with 50mm thick C20 fine stone.

4. The composite sealing method for ultra-deep foundation pit dewatering well according to claim 3 is characterized by: In step 4, fill to 620mm below the mouth of the steel casing (2).

5. The composite sealing method for ultra-deep foundation pit dewatering well according to claim 4 is characterized by: In step seven, the radius of the steel cover plate (3) is 10 mm smaller than the mouth of the steel sleeve (2).

Images