Descending and retaining integrated foundation pit water stopping method for building dense area

Abstract

A descending and retaining integrated foundation pit water stopping method for a building dense area sequentially comprises the following steps that (1) surveying and setting out are conducted, and the edge position of a foundation pit is found; (2) marking the construction position of the waterproof curtain; (3) drilling the first mark point, and putting a steel pipe into the hole; (4) finding a second mark point at an appointed distance, drilling the second mark point, and putting a steel pipe into the hole; (5) finding a third mark point between the first mark point and the second mark point, drilling, putting a reinforcement cage into a hole, and then pouring concrete; and (6) marking the steel pipe as a dewatering well according to design requirements, and lowering a water pump into the steel pipe marked as the dewatering well. According to the method, the construction speed can be increased, meanwhile, damage to surrounding buildings is small, the used steel pipe can serve as a dewatering well and can also serve as a part of a waterproof curtain, the construction steps are simplified, used steel can be recycled, the construction cost is reduced, and the method is suitable for application and popularization.

Description

Technical Field

[0001] The invention belongs to the technical field of foundation pit water-stopping construction methods, and in particular relates to a foundation pit water-stopping method that integrates lowering and blocking in a building-intensive area. Background Art

[0002] During the construction of the foundation pit, water-stopping devices need to be constructed. Commonly used water-stopping structures include water-stopping walls. Water-stopping walls are costly to construct. The foundation pit is surrounded by water-stopping walls to prevent external water from entering the foundation pit. For the foundation pit, in order to achieve the purpose of precipitation, precipitation wells need to be set up both outside and inside the foundation pit. Water is pumped out through the precipitation wells to prevent water from entering the foundation pit. At present, the precipitation wells constructed outside the foundation pit are often constructed during the construction of the water-stopping wall; and the precipitation wells inside the foundation pit are often constructed at the same time during the construction of the foundation pit.

[0003] Waterstop walls are generally cast in concrete, but after the foundation pit construction is completed, the waterstop walls are often not used again, which greatly increases the cost of the foundation pit.

[0004] As described in the prior art, two types of water-stopping support methods are underground continuous wall and interlocking pile retaining wall.

[0005] After the underground continuous wall is slotted with a slotting machine, concrete is poured to form an underground continuous wall. The underground continuous wall can play a supporting role on the one hand, and on the other hand, it can play a waterproof effect to prevent groundwater outside the foundation pit from seeping into the foundation pit. This method has high requirements for pouring time. It is necessary to complete the pouring of the entire underground continuous wall in a short time, otherwise it will affect the waterproof effect. At the same time, this method uses a large amount of concrete and has high construction costs.

[0006] The interlocking pile retaining wall adopts skip hole construction. During the construction of the second sequence pile, the pile body of the first sequence pile is cut by a hole-making machine to form a continuous interlocking pile wall, and concrete is poured into the hole. This method has high strength and good interlocking properties. However, the amount of concrete used is large and the construction cost is high.

[0007] Both of the above two construction methods require precipitation treatment. The current precipitation includes two steps. One is precipitation outside the foundation pit. Through precipitation outside the foundation pit, the water level outside the water-stop curtain is lowered to prevent the water-stop curtain from being pressed by a large amount of groundwater; the other is precipitation inside the foundation pit. Through precipitation inside the foundation pit, the water level inside the foundation pit is lowered to facilitate the excavation of the foundation pit.

[0008] The drainage wells outside the foundation pit are often drilled on the outside of the water-stop curtain, and there are more than one of them. This method also greatly increases the construction cost and reduces the construction speed. At the same time, the drainage wells outside the foundation pit will often disturb the strata outside the foundation pit. Using them in densely built areas may cause cracks in other buildings. Summary of the invention

[0009] The present invention aims to provide a foundation pit water stopping method with integrated lowering and retaining function in building-dense areas, which has a simple structure and good use effect.

[0010] In order to solve the above technical problems, the present invention provides the following technical solutions: a foundation pit water stopping method for lowering and blocking in a densely built area, the method comprising the following steps in sequence:

[0011] (1) Measure and lay out the lines to find the edge of the foundation pit;

[0012] (2) Mark the construction location of the water-stop curtain;

[0013] (3) Drill a hole at the first marked point and lower the steel pipe into the hole;

[0014] (4) Find the second marking point at a specified distance, drill a hole at the second marking point, and lower the steel pipe into the hole;

[0015] (5) Find the third marking point between the first marking point and the second marking point, drill a hole at the third marking point, lower the steel cage into the hole, and then pour concrete;

[0016] (6) Mark the steel pipe as a drainage well according to the design requirements and lower the water pump into the steel pipe marked as the drainage well.

[0017] The integrated foundation pit water stopping method for lowering and retaining water in densely built-up areas as described in claim 1 is characterized in that: except for the steel pipes marked as drainage wells, which are open at the bottom, the remaining steel pipes are sealed at the ends before step (3).

[0018] After step (1), a platform is set near the edge of the foundation pit.

[0019] The masonry method of the platform is as follows: a trench with a width of 200 mm and a depth of 800 to 1000 mm is excavated with a trench wall machine. If the geology is soft, after excavating a section of the trench, the trench is protected by mud walls. In this embodiment, the length of a section of the trench is the distance of trench excavation once; otherwise, the next section of the trench is excavated directly; the circumferential trenches along the edge of the foundation pit are the first trench, the second trench, the third trench...the nth trench; then, the first trench is excavated first, followed by the third trench, the second trench is excavated again, the fifth trench is excavated next, the fourth trench is excavated next,..., the nth trench is excavated, and finally the n-1th trench is excavated. After the excavation of the entire trench around the edge of the foundation pit is completed, concrete is poured into the trench and waited for it to solidify.

[0020] Before step (3), the steel pipe needs to be prefabricated and the outer edge of the steel pipe is forged to form an arc groove facing outward, and the length direction of the arc groove is the same as the height direction of the steel pipe; the arc where the arc groove cross section is located is cocircular with the circumference of the third marking point drilling hole.

[0021] After step (6), the foundation pit is excavated. When the foundation pit is excavated to the first design elevation, prefabricated steel support frames are placed in the foundation pit. The number of prefabricated steel support frames is the same as the number of design elevation layers of the foundation pit. The prefabricated steel support frames with the same number of design elevation layers are connected to each steel pipe arranged circumferentially.

[0022] When the foundation pit is excavated to the second-layer design elevation, the prefabricated steel support frames except the top one are slid down to the second-layer design elevation; at the same time, the top prefabricated steel support frame is welded to the steel pipe at the first-layer design elevation; the cycle is repeated until the prefabricated steel support frame is connected to the lowest design elevation.

[0023] The prefabricated steel support frame includes a main beam and a secondary beam connected to the main beam. There are 4 main beams, and the 4 main beams correspond to the 4 sides of the foundation pit respectively. The main beam is welded to the secondary beam. The secondary beam includes a first beam and a second beam. The first beam is inclined, and the two ends of the first beam are respectively welded to two connected main beams. The second beam is horizontally set, and the second beam is connected to two opposite main beams.

[0024] The manufacturing method of the prefabricated steel support frame is as follows: first, complete the manufacturing of a main beam and the first beam connected to it outside the foundation pit; then, hoist it to the foundation pit to complete the connection between the main beam and the first beam and the second beam; finally, after the prefabricated steel support frame is placed in the foundation pit, it is connected to the steel pipe by welding; when the prefabricated steel support frame is above its design elevation, it is first screwed to the steel pipe, and when it needs to move downward, the bolts are loosened, and when it is moved to its design elevation, the steel pipe is welded to the prefabricated steel support frame.

[0025] Through the above technical scheme, the technical effects of the present invention are as follows: 1. The integrated foundation pit water-stopping method for lowering and blocking in densely built areas described in this embodiment can improve the construction speed, and at the same time, it has little destructiveness to surrounding buildings. In addition, the steel pipes used therein can be used as both a precipitation well and a part of a water-stopping curtain, which simplifies the construction steps. The used steel can also be recycled, which reduces the construction cost and is suitable for popularization and use. 2. In this embodiment, when the foundation pit construction is completed, the steel support frame can be disassembled while backfilling; at the same time, after the foundation pit construction is completed, the steel pipe can be separated from the adjacent concrete column by cutting, and then backfilled inside. In this way, the recovery rate of the steel support frame and the steel pipe is improved, and the construction cost is greatly reduced. At the same time, the construction speed is fast and the disturbance to the surrounding buildings is small. 3. A part of the prefabricated steel support frame can be prefabricated outside the foundation pit, which can be well combined with the steel pipe. On the one hand, it can support the water-stop curtain to prevent it from deformation. On the other hand, during the construction process, it can be moved with the steel pipe as a guide, saving positioning time. Finally, the prefabricated steel support frame can be dismantled later, saving costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the structure of the present invention;

[0027] Figure 2 This is a schematic diagram of the prefabricated steel support frame structure. DETAILED DESCRIPTION

[0028] The integrated water stopping method of foundation pit in densely built areas, such as Figure 1 and Figure 2 As shown, the present application is suitable for built-up areas, where no major construction changes can be made to the surrounding areas and the operating space is small.

[0029] The method comprises the following steps in sequence:

[0030] (1) Measure and lay out the lines and find the edge of the foundation pit 1; after this step, a platform is set up near the edge of the foundation pit 1 and along the circumference of the edge of the foundation pit 1. The platform is not shown in the figure. The platform is located outside the water-stop curtain of this embodiment and is set around the circumference of the water-stop curtain. The vertical distance between the platform and the water-stop curtain is 300 mm to 800 mm. Among them, measuring and laying out the lines is a mature existing technology, and this embodiment will not repeat its specific implementation method.

[0031] (2) The masonry method of the platform is as follows: a trench with a width of 200 mm and a depth of 8000-10000 mm is excavated with a trench wall machine. If the geology is soft, after excavating a section of the trench, the trench is protected by mud walls. In this embodiment, the length of a section of the trench is the distance of trench excavation once; otherwise, the next section of the trench is excavated directly; the trenches along the circumferential direction of the edge of the foundation pit 1 are the first trench, the second trench, the third trench, and the nth trench; then, the first trench is excavated first, followed by the third trench, the second trench is excavated again, the fifth trench is excavated next, the fourth trench is excavated next, and the nth trench is excavated last. After the excavation of the entire trench around the edge of the foundation pit 1 is completed, concrete is poured into the trench and waited for it to solidify.

[0032] (2) Mark the construction position of the water-stop curtain. When marking the position of the water-stop curtain, only two data need to be measured. The first data is: its circumferential position, and the second data is: its distance from the platform. With these two data, the position of the water-stop curtain can be easily determined.

[0033] (3) Drill a hole at the first marked point and lower the steel pipe into the hole; before this step, the steel pipe needs to be prefabricated and the outer edge of the steel pipe is forged to form an arc groove facing outward. The length direction of the arc groove is the same as the height direction of the steel pipe, that is, the arc groove runs through the entire height direction of the steel pipe from top to bottom.

[0034] The arc of the arc groove cross section is cocircular with the circumference of the hole drilled at the third marking point, so that the steel pipe and the poured concrete are arranged in a straight line.

[0035] (4) Find the second marking point at a specified distance, drill a hole at the second marking point, and lower the steel pipe into the hole. During the process of lowering the steel pipe, the steel pipe must be kept vertical.

[0036] (5) Find the third mark point between the first mark point and the second mark point. The third mark point is at the same distance from the first mark point and the second mark point. Drill a hole at the third mark point, lower the steel cage into the hole, and then pour concrete. The poured concrete enters the arc grooves of the steel pipes on both sides, achieving bite with the steel pipes, improving the effect and ensuring the strength.

[0037] (6) Mark the steel pipe as a drainage well according to the design requirements, and lower the water pump into the steel pipe marked as the drainage well. In this embodiment, except for the steel pipe marked as the drainage well, the steel pipe with an open bottom end is used, and the other steel pipes are sealed at the ends before step (3). The end sealing process described in this embodiment refers to the bottom end.

[0038] The steel pipe is divided into a steel pipe precipitation well 31 and an ordinary steel pipe 32 according to whether it is a precipitation well. The bottom end of the steel pipe precipitation well 31 is sealed, and the bottom end of the ordinary steel pipe 32 is sealed. Among them, how far to set a precipitation well is determined according to the design requirements, generally 500-800mm.

[0039] This embodiment directly eliminates the need to set up a drainage well near the water-stop curtain by marking the steel pipe as a drainage well, and combines the water-stop curtain and the drainage well into one, making the construction convenient and fast; in addition, the steel pipe is used here to replace the traditional concrete pouring, and the steel pipe can be removed later, saving construction costs. In addition, in this way, the drainage well outside the water-stop curtain can be omitted, and the drainage well close to the water-stop curtain in the foundation pit can also be omitted.

[0040] At the same time, even if the steel pipe is used as an ordinary steel pipe, it also has a good effect. Specifically, water sometimes seeps into the foundation pit water-stop curtain to form a gush. In this embodiment, there are many steel pipes. If water seeps into the steel pipe, it can also be temporarily stored in the steel pipe, which greatly alleviates the phenomenon of gush.

[0041] In addition, concrete with steel cages is poured between the steel pipes, which has strong bite and high strength.

[0042] After step (6), the foundation pit 1 is excavated. When the foundation pit 1 is excavated to the first design elevation, prefabricated steel support frames are placed in the foundation pit 1. Here, the number of prefabricated steel support frames placed is the same as the number of design elevation layers of the foundation pit 1; the prefabricated steel support frames with the same number of design elevation layers are all connected to each steel pipe arranged circumferentially.

[0043] When foundation pit 1 is excavated to the second-layer design elevation, the prefabricated steel support frames except the top one are slid down to the second-layer design elevation; at the same time, the top prefabricated steel support frame is welded to the steel pipe at the first-layer design elevation; the cycle is repeated until the prefabricated steel support frame is connected to the lowest design elevation.

[0044] In this embodiment, the water-stop curtain can be supported by setting up a prefabricated steel support frame, which adopts an internal support method, eliminating devices such as anchor rods, thereby reducing the disturbance to the geology outside the foundation pit 1, and is particularly suitable for construction in densely built areas.

[0045] At the same time, the prefabricated steel support frame is constructed quickly, and most of the work has been completed outside the foundation pit 1, and only welding needs to be done inside the foundation pit 1.

[0046] In addition, when placing the prefabricated steel support frames, all the prefabricated steel support frames are connected to the steel pipes together. As the foundation pit 1 is excavated, each prefabricated steel support frame is slid downward along the steel pipes, saving the subsequent positioning process. In this embodiment, when the prefabricated steel support frame is not at its elevation design layer, its connection with the steel pipe is a detachable connection, and when it reaches its elevation design layer, the connection method used is welding.

[0047] The structure of the prefabricated steel support frame used in this embodiment is as follows: the prefabricated steel support frame includes a main beam 4 and a secondary beam connected to the main beam 4, the number of the main beams 4 is 4, and the 4 main beams 4 correspond to the 4 sides of the foundation pit 1 respectively; the main beam 4 is welded to the secondary beam; the secondary beam includes a first beam 5 and a second beam 6, the first beam 5 is inclined, and the two ends of the first beam 5 are respectively welded to two connected main beams 4; the second beam 6 is horizontally arranged, and the second beam 6 is connected to two opposite main beams 4.

[0048] The integrated foundation pit water-stopping method for lowering and blocking in densely built-up areas as described in claim 1 is characterized in that: the method for making the prefabricated steel support frame is: first, complete the production of a main beam 4 and a primary beam 5 connected to it outside the foundation pit 1; then, hoist it to the foundation pit 1, and complete the connection between the main beam 4 and the primary beam 5 and the secondary beam 6; finally, after the prefabricated steel support frame is placed in the foundation pit 1, it is connected to the steel pipe by welding; when the prefabricated steel support frame is above its design elevation, it is first screwed to the steel pipe, and when it needs to move downward, the bolt 8 is loosened, and when it moves to its design elevation, the steel pipe is welded to the prefabricated steel support frame.

[0049] In this embodiment, the prefabricated steel support frame is completed in advance outside the foundation pit 1. The extent to which the prefabricated steel support frame is prefabricated needs to be determined according to the size of the foundation pit 1 and the size of the lifting setting. When the foundation pit 1 is too large, there is no need to pre-install the entire prefabricated steel support frame. A part of it can be pre-installed and the remaining part can be welded inside the foundation pit 1.

[0050] The prefabricated steel support frame is connected to two relatively arranged clamping plates 7, and the cross-section of the clamping plates 7 is arc-shaped. The two relatively arranged clamping plates 7 can clamp the steel pipe therebetween. At the same time, bolts 8 are connected between the two clamping plates 7. When temporary fixation is required, the prefabricated steel support frame is connected to the steel pipe by bolts 8. When it needs to be moved downward, the clamping plates 7 can also provide a certain guide for the sliding of the prefabricated steel support frame, thereby solving the positioning position. After sliding into place, the prefabricated steel support frame can be welded to the steel pipe.

[0051] In this way, initially, the prefabricated steel support frame is clamped on the steel pipe. When the prefabricated steel support frame is moved to the designed elevation, the prefabricated steel support frame is welded to the steel pipe.

[0052] In this embodiment, after the construction of the foundation pit 1 is completed, the steel support frame can be disassembled while backfilling; at the same time, after the construction of the foundation pit 1 is completed, the steel pipe can be separated from the adjacent concrete column by cutting, and then backfilled inside. In this way, the recovery rate of the steel support frame and the steel pipe is improved, the construction cost is greatly reduced, and at the same time, the construction speed is fast and the disturbance to the surrounding buildings is small.

[0053] The integrated foundation pit water-stopping method for lowering and blocking in densely built-up areas described in this embodiment can increase the construction speed while causing little damage to surrounding buildings. In addition, the steel pipes used therein can be used as both a drainage well and as part of a water-stopping curtain, thus simplifying the construction steps. The used steel can also be recycled, thus reducing the construction cost and being suitable for popularization and use.

Claims

1. A water-stopping method for foundation pits in densely built areas with integrated lowering and retaining functions, characterized in that: The method comprises the following steps in sequence: (1) Measure and lay out the lines to find the edge of the foundation pit; (2) Mark the construction location of the water-stop curtain; (3) Drill a hole at the first marked point and lower the steel pipe into the hole; (4) Find the second marking point at a specified distance, drill a hole at the second marking point, and lower the steel pipe into the hole; (5) Find the third marking point between the first marking point and the second marking point, drill a hole at the third marking point, lower the steel cage into the hole, and then pour concrete; (6) Mark the steel pipe as a drainage well according to the design requirements and lower the water pump into the steel pipe marked as the drainage well.

2. The method for stopping water in foundation pits in densely built-up areas as claimed in claim 1, characterized in that: Except for the steel pipes marked as drainage wells, which have an open bottom, the other steel pipes are sealed at the ends before step (3).

3. The method for stopping water in foundation pits in densely built-up areas as claimed in claim 2, characterized in that: After step (1), a platform is set near the edge of the foundation pit.

4. The method for stopping water in foundation pits in densely built-up areas as claimed in claim 3, characterized in that: The masonry method of the platform is: use a trench wall machine to dig a trench with a width of 200mm and a depth of 800-1000mm. If the geology is soft, after a section of the trench is excavated, the trench is protected by mud walls. In this embodiment, the length of a section of the trench is the distance of the trench excavation once; otherwise, the next section of the trench is excavated directly; The circumferential grooves along the edge of the foundation pit are the first groove, the second groove, the third groove, and the nth groove; then, the first groove is excavated first, followed by the third groove, the second groove, the fifth groove, the fourth groove, and finally the n-1th groove. After the excavation of the grooves around the edge of the foundation pit is completed, concrete is poured into the grooves and waited for solidification.

5. The method for stopping water in foundation pits in densely built-up areas as claimed in claim 4, characterized in that: Before step (3), the steel pipe needs to be prefabricated and the outer edge of the steel pipe is forged to form an arc groove facing outward, and the length direction of the arc groove is the same as the height direction of the steel pipe; the arc where the arc groove cross section is located is cocircular with the circumference of the third marking point drilling hole.

6. The method for stopping water in foundation pits in densely built-up areas as claimed in claim 5, characterized in that: After step (6), the foundation pit is excavated. When the foundation pit is excavated to the first design elevation, prefabricated steel support frames are placed in the foundation pit. The number of prefabricated steel support frames is the same as the number of design elevation layers of the foundation pit. The prefabricated steel support frames with the same number of design elevation layers are connected to each steel pipe arranged circumferentially.

7. The method for stopping water in foundation pits in densely built-up areas as claimed in claim 6, characterized in that: When the foundation pit is excavated to the second-layer design elevation, the prefabricated steel support frame, except for the topmost one, is slid down to the second-layer design elevation; at the same time, the topmost prefabricated steel support frame is welded to the steel pipe at the first-layer design elevation position; The cycle continues until the prefabricated steel support frame is connected to the lowest design elevation.

8. The method for stopping water in foundation pits in densely built-up areas as claimed in claim 7, characterized in that: The prefabricated steel support frame includes a main beam and a secondary beam connected to the main beam. There are 4 main beams, and the 4 main beams correspond to the 4 sides of the foundation pit respectively. The main beam is welded to the secondary beam. The secondary beam includes a first beam and a second beam. The first beam is inclined, and the two ends of the first beam are respectively welded to two connected main beams. The second beam is horizontally set, and the second beam is connected to two opposite main beams.

9. The method for stopping water in foundation pits in densely built-up areas as claimed in claim 8, characterized in that: The manufacturing method of the prefabricated steel support frame is as follows: first, complete the manufacturing of a main beam and the first beam connected to it outside the foundation pit; then, hoist it to the foundation pit to complete the connection between the main beam and the first beam and the second beam; finally, after the prefabricated steel support frame is placed in the foundation pit, it is connected to the steel pipe by welding; when the prefabricated steel support frame is above its design elevation, it is first screwed to the steel pipe, and when it needs to move downward, the bolts are loosened, and when it is moved to its design elevation, the steel pipe is welded to the prefabricated steel support frame.

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