A foundation pit double-tube jet grouting pile water-stop curtain support and its construction method

Abstract

The invention relates to the technical field of underground engineering foundation pit support, and discloses a foundation pit double-tube rotary jet pile water-stop curtain support and a construction method thereof, comprising rotary jet piles, an underground continuous wall, a crown beam, a first-drain-then-fix sand well and a pumping assembly, wherein the rotary jet piles are engaged with each other, a crown beam and a concrete top plate are arranged on the top of the rotary jet piles, and the rotary jet piles and the underground continuous wall are connected as a whole through a connecting beam; the three-layer water-stop curtain support form finally formed by the application is conducive to the later stability of the foundation pit; the first-drain-then-fix sand well is arranged to meet the early drainage requirements and the foundation strength requirements of the later building enclosure.

Description

Technical Field

[0001] The invention relates to the technical field of underground engineering foundation pit support, and in particular to a foundation pit double-tube rotary jet pile water-stop curtain support and a construction method thereof. Background Art

[0002] The foundation pit of the existing technology can be supported by setting up internal supports and continuous walls, but there are some problems in the current technology. For example, in strata with abundant groundwater, especially during construction in the rainy season, it is easy to have untimely drainage. It is necessary to set up a water-stop curtain support form that can dynamically adjust the water pressure and drainage. Summary of the invention

[0003] In view of the shortcomings of the prior art, the present invention provides a foundation pit double-tube rotary jet pile water-stop curtain support and a construction method thereof, which has the advantages of being able to effectively control the displacement of the foundation pit without setting up internal supports or anchor cables, meet the overall stability requirements, and improve the scope of application of the double-row pile support system.

[0004] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a foundation pit double-tube jet grouting pile water-stop curtain support, comprising jet grouting piles, underground continuous walls, cap beams, sand-discharging-first-and-fixing-later wells, and pumping components, wherein the jet grouting piles are engaged with each other, a cap beam and a concrete top plate are arranged on the top of the jet grouting piles, and the jet grouting piles and the underground continuous wall are connected as a whole through a connecting beam;

[0005] A well for first draining and then fixing sand is arranged behind the jet grouting pile, and the well for first draining and then fixing sand is buried between the pile and soil. A pumping assembly is fixedly connected to each well for first draining and then fixing sand. The pumping assembly includes a water pump and a semicircular drainage pipe. A water return groove is arranged at intervals in the vertical direction in each semicircular drainage pipe. The water return groove at the lower end of the semicircular drainage pipe is located at the bottom of the sand well. A water storage chamber is arranged in the water return groove. The semicircular drainage pipe is plugged into the water return groove. The input end of the water pump is fixedly connected to the semicircular drainage pipe. The water in the well for first draining and then fixing sand is pumped to the ground and merged into the municipal pipe network through the water pump.

[0006] After the foundation pit construction is completed, concrete is back-poured into the backflow trough, and the concrete is infiltrated into the sand well to consolidate the sand wells that are first drained and then fixed. Finally, a three-layer water-stop curtain support of rotary jet piles, sand wells that are first drained and then fixed, and underground continuous walls is formed.

[0007] The backfilled concrete includes a waterproofing agent.

[0008] The water return trough is configured as an inverted rectangular trough with an opening facing downward, wherein a long installation groove is provided on the upper portion of the water return trough, and the long installation groove cooperates with the installation of a semicircular drain pipe.

[0009] Holes are evenly arranged on the surface of the semicircular drainage pipe for water permeability.

[0010] A pressure type water level gauge is arranged in the sand-draining-before-fixing well.

[0011] In addition, a construction method for foundation pit double-tube jet grouting pile water-stop curtain support is provided, and the steps are as follows:

[0012] Step (1): Survey and lay out the lines and locate the positions. First, check and sign the benchmark points, base axis lines and leveling points of the construction site. The calibrated benchmark points should be clearly marked and numbered and well protected. Use a total station and a steel tape measure to measure the pile positions using the coordinate method and measure and locate all the pile positions in the construction area.

[0013] Step (2): The drilling rig is positioned at the designed hole position, the drill rod head is aligned with the hole center, and a horizontal correction is performed first. The drill rod of the drilling rig is positioned using a drill rod guide frame, so that the drill rod axis is vertically aligned with the center of the hole. The allowable verticality deviation shall not exceed 0.5%;

[0014] Step (3): Construction of the jet grouting pile 1 and the underground continuous wall 2. First, drill holes according to the designed positions and construct the jet grouting pile 1 and the underground continuous wall 2. Use the double pipe method to construct the high-pressure jet grouting water-stopping pile. First, use a geological small-diameter drilling rig to drill holes, insert the grouting pipe into the hole, and then use a high-pressure grouting pump to spray cement slurry from the nozzle. While spraying, rotate and lift at the same time, and finally form a cylindrical consolidation body in the soil. The deviation between the hole position and the designed position is controlled to be no more than 50 mm. The distance between the injection hole and the high-pressure grouting pump is no more than 50 mm. Insert the pipe while drilling. During the insertion process, in order to prevent mud and sand from clogging the nozzle, a method of injecting water while inserting the pipe is adopted, and the water pressure is controlled not to exceed 1 MPa.

[0015] The jet grouting piles are interlocked with each other. After the strength of the jet grouting piles meets the requirements, a cap beam 3 and a concrete top plate are arranged on the top of the piles, and the jet grouting piles 1 are connected to the underground continuous wall 2 as a whole through a connecting beam 7.

[0016] Step (4): construct a sand well for drainage and consolidation and a semicircular drainage pipe. First, dig out the location of the sand well and fill it with gravel and crushed stone. When installing the water tank, set it downward along the depth of 5 meters to ensure the permeability and density of the sand well. At the same time, set a semicircular drainage pipe in the sand well and a pressure water level gauge in the sand well. When the pressure water level gauge exceeds the set threshold, insert the pumping pipe into the semicircular drainage pipe and use the water pump to pump water. By reducing the water head on the side of the sand well for drainage and consolidation, the double-row pile support is stabilized. When the pressure water level gauge value is lower than the threshold, cover the semicircular drainage pipe to protect its plug hole.

[0017] Step (5): After the foundation pit construction is completed, concrete is poured back into the backwater trough. After the backwater trough is filled with concrete, the reverse setting is conducive to forming an enlarged head in the backwater trough. Under the reverse extrusion of the backwater trough, the overflowing concrete is squeezed into the gravel and crushed stone pores of the first-drain and then-fixed sand well, so that the first-drain and then-fixed sand well is consolidated, and finally a three-layer water-stop curtain support of the rotary jet pile, the first-drain and then-fixed sand well and the underground continuous wall is formed.

[0018] Compared with the prior art, the present invention provides a foundation pit double-tube rotary jet pile water-stop curtain support and a construction method thereof, which has the following beneficial effects:

[0019] (1) The double-tube jet-jet pile water-stop curtain support of the foundation pit improves the overall lateral stiffness of the support structure, enhances the support structure's ability to resist bending, overturning, and water and soil pressure outside the pit, thereby effectively controlling the deformation of the foundation pit; there is no need to set up lateral support and anchor systems;

[0020] (2) The three-layer water-stop curtain support finally formed in this application is conducive to the stability of the foundation pit in the later stage;

[0021] (3) This application sets up a sand-fixing well that drains first and then consolidates the sand, which can meet the drainage requirements in the early stage and the foundation strength requirements for the later building enclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the support arrangement of the double-tube jet-jet pile water-stop curtain in the foundation pit;

[0023] Figure 2 This is a schematic diagram of the cross-sectional arrangement of the double-tube jet-jet pile water-stop curtain support for the foundation pit;

[0024] Figure 3 This is the elevation drawing of the double-tube jet-jet pile water-stop curtain support for the foundation pit;

[0025] Figure 4 This is a schematic diagram of the arrangement of the counter-water tank;

[0026] Figure 5 This is a schematic diagram of the installation of the counter sink;

[0027] Figure 6 This is a schematic diagram of the discontinuous distribution of wells that drain first and then fix sand;

[0028] Figure 7 This is a schematic diagram of the continuous distribution of wells that drain first and then fix sand.

[0029] In the figure: 1. Jet jet piles; 2. Underground continuous wall; 3. Crown beam; 4. Drainage-first-then-sand-fixation well; 5. Pumping assembly; 6. Concrete top plate; 7. Connecting beam; 8. Water storage chamber; 9. Backflow trough; 10. Long installation groove; 11. Semicircular drainage pipe; 12. Water pump; 13. Pumping pipe. DETAILED DESCRIPTION

[0030] In order to better understand the purpose, structure and function of the present invention, the following is a further detailed description of a foundation pit double-tube rotary jet pile water-stop curtain support and a construction method thereof in conjunction with the accompanying drawings.

[0031] See also Figure 1-7 The present invention is: a foundation pit double-tube jet grouting water-stop curtain support, comprising a jet grouting pile 1, an underground continuous wall 2, a crown beam 3, a first-drain and then-fix sand well 4, and a pumping assembly 5, characterized in that: the jet grouting piles 1 are engaged with each other, a crown beam 3 and a concrete top plate 6 are arranged on the top of the jet grouting pile, and the jet grouting pile 1 and the underground continuous wall 2 are connected as a whole through a connecting beam 7;

[0032] Wherein, a well 4 for first draining and then fixing sand is arranged at the rear of the jet grouting pile 1, and the well 4 for first draining and then fixing sand is buried between the pile and soil, and a pumping assembly 5 is fixedly connected in each of the wells 4 for first draining and then fixing sand, and the pumping assembly 5 comprises a water pump 12 and a semicircular drainage pipe 11, and each of the semicircular drainage pipes 11 is provided with a return water trough 9 at intervals in the vertical direction, and the return water trough at the lower end of the semicircular drainage pipe is located at the bottom of the sand well, and a water storage chamber 8 is arranged in the return water trough 9, and the semicircular drainage pipe 11 is inserted in the return water trough 9, and the input end of the pump 12 is fixedly connected to the semicircular drainage pipe, and the water in the well for first draining and then fixing sand is pumped to the ground through the pumping pipe 13 by the water pump and merged into the municipal pipe network;

[0033] After the foundation pit construction is completed, concrete is back-poured into the backflow trough, and the concrete is infiltrated into the sand well to consolidate the sand wells that are first drained and then fixed. Finally, a three-layer water-stop curtain support of rotary jet piles, sand wells that are first drained and then fixed, and underground continuous walls is formed.

[0034] The sand-draining-then-fixing wells 4 are distributed intermittently or are arranged along one side of the foundation pit; the interval between the intermittently distributed wells is two meters, and the length of each intermittently distributed well is five meters.

[0035] The backfilled concrete includes a waterproofing agent.

[0036] The water return trough is configured as an inverted rectangular trough with an opening facing downward, wherein a long installation groove 10 is provided on the upper portion of the water return trough, and the long installation groove cooperates with the installation of a semicircular drain pipe 11 .

[0037] Holes are evenly arranged on the surface of the semicircular drainage pipe for water permeability.

[0038] A pressure type water level gauge is arranged in the sand-draining-before-fixing well 4 .

[0039] Provided is a construction method for foundation pit double-tube rotary jet pile water-stop curtain support, the steps of which are:

[0040] Step (1): Survey and lay out the lines and locate the positions. First, check and sign the benchmark points, base axis lines and leveling points of the construction site. The calibrated benchmark points should be clearly marked and numbered and well protected. Use a total station and a steel tape measure to measure the pile positions using the coordinate method and measure and locate all the pile positions in the construction area.

[0041] Step (2): The drilling rig is positioned at the designed hole position, the drill rod head is aligned with the hole center, and a horizontal correction is performed first. The drill rod of the drilling rig is positioned using a drill rod guide frame, so that the drill rod axis is vertically aligned with the center of the hole. The allowable verticality deviation shall not exceed 0.5%;

[0042] Step (3): Construction of the jet grouting pile 1 and the underground continuous wall 2. First, drill holes according to the designed positions and construct the jet grouting pile 1 and the underground continuous wall 2. Use the double pipe method to construct the high-pressure jet grouting water-stopping pile. First, use a geological small-diameter drilling rig to drill holes, insert the grouting pipe into the hole, and then use a high-pressure grouting pump to spray cement slurry from the nozzle. While spraying, rotate and lift at the same time, and finally form a cylindrical consolidation body in the soil. The deviation between the hole position and the designed position is controlled to be no more than 50 mm. The distance between the injection hole and the high-pressure grouting pump is no more than 50 mm. Insert the pipe while drilling. During the insertion process, in order to prevent mud and sand from clogging the nozzle, a method of injecting water while inserting the pipe is adopted, and the water pressure is controlled not to exceed 1 MPa.

[0043] The jet grouting piles are interlocked with each other. After the strength of the jet grouting piles meets the requirements, a cap beam 3 and a concrete top plate are arranged on the top of the piles, and the jet grouting piles 1 are connected to the underground continuous wall 2 as a whole through a connecting beam 7.

[0044] Step (4): construct a sand well for drainage and consolidation and a semicircular drainage pipe. First, dig out the location of the sand well and fill it with gravel and crushed stone. When installing the water tank, set it downward along the depth of 5 meters to ensure the permeability and density of the sand well. At the same time, set a semicircular drainage pipe in the sand well and a pressure water level gauge in the sand well. When the pressure water level gauge exceeds the set threshold, insert the pumping pipe into the semicircular drainage pipe and use the water pump to pump water. By reducing the water head on the side of the sand well for drainage and consolidation, the double-row pile support is stabilized. When the pressure water level gauge value is lower than the threshold, cover the semicircular drainage pipe to protect its plug hole.

[0045] Step (5): After the foundation pit construction is completed, concrete is poured back into the backwater trough. After the backwater trough is filled with concrete, the reverse setting is conducive to forming an enlarged head in the backwater trough. Under the reverse extrusion of the backwater trough, the overflowing concrete is squeezed into the gravel and crushed stone pores of the first-drain and then-fixed sand well, so that the first-drain and then-fixed sand well is consolidated, and finally a three-layer water-stop curtain support of the rotary jet pile, the first-drain and then-fixed sand well and the underground continuous wall is formed.

[0046] It is to be understood that the present invention is described by some embodiments, and it is known to those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the scope of protection of the present invention.

Claims

1. A double-tube jet grouting pile water-stop curtain support for a foundation pit, comprising jet grouting piles (1), an underground continuous wall (2), a crown beam (3), a first-draining and then-fixing sand well (4), and a pumping assembly (5), characterized in that: The jet grouting piles (1) are interlocked with each other, a cap beam (3) and a concrete top plate are arranged on the top of the jet grouting piles, and the jet grouting piles (1) are connected to the underground continuous wall (2) as a whole through a connecting beam (7); A sand-fixing well (4) is arranged behind the jet grouting pile (1), the sand-fixing well (4) being buried between the pile and soil, and a pumping assembly (5) is fixedly connected to each of the sand-fixing wells (4), the pumping assembly (5) comprising a pumping pump (12) and a semicircular drainage pipe (11), and each of the semicircular drainage pipes (11) is provided with a water return groove (9) at intervals in a vertical direction, the water return groove at the lower end of the semicircular drainage pipe is located at the bottom of the sand well, and a water storage chamber (8) is arranged in the water return groove (9), the semicircular drainage pipe (11) is plugged into the water return groove (9), the input end of the water pump (12) is fixedly connected to the semicircular drainage pipe, and water in the sand-fixing well (4) is pumped to the ground through the pumping pipe (13) by the water pump and then merged into the municipal pipe network; After the foundation pit construction is completed, concrete is poured back into the backwater tank and the concrete is infiltrated into the sand well to consolidate the sand well, eventually forming a three-layer water-stop curtain support of jet grouting piles, sand wells for drainage and consolidation, and underground continuous walls; The water return trough is configured as an inverted rectangular trough with an opening facing downward, wherein a long installation groove (10) is provided on the upper portion of the water return trough, and the long installation groove cooperates with the installation of a semicircular drainage pipe (11); the first-drainage and then-fixation sand wells (4) are distributed intermittently or are arranged in a full length on one side of the foundation pit.

2. A double-tube jet grouting water-stop curtain support for foundation pit according to claim 1, characterized in that: The backfilled concrete includes a waterproofing agent.

3. The double-tube jet grouting pile water-stop curtain support for foundation pit according to claim 1, characterized in that: The interval between the first-draining and then-fixing sand wells (4) is two meters, and the length of each intermittently distributed sand well is five meters.

4. A double-tube jet grouting pile water-stop curtain support for foundation pit according to claim 1, characterized in that: Holes are evenly arranged on the surface of the semicircular drainage pipe for water permeability.

5. The double-tube jet grouting water-stop curtain support for foundation pit according to claim 1 is characterized by: A pressure-type water level gauge is provided in the sand-draining-then-fixing well (4).

6. A construction method for foundation pit double-tube jet grouting pile water-stop curtain support according to any one of claims 1 to 4, the steps of which are: Step (1): Survey and lay out the lines and locate the positions. First, check and sign the benchmark points, base axis lines and leveling points of the construction site. The calibrated benchmark points should be clearly marked and numbered and well protected. Use a total station and a steel tape measure to measure the pile positions using the coordinate method and measure and locate all the pile positions in the construction area. Step (2): The drilling rig is positioned at the designed hole position, the drill rod head is aligned with the hole center, and a horizontal correction is performed first. The drill rod of the drilling rig is positioned using a drill rod guide frame, so that the drill rod axis is vertically aligned with the center of the hole. The allowable verticality deviation shall not exceed 0.5%; Step (3): Construction of the jet grouting pile (1) and the underground continuous wall (2), firstly drilling holes according to the designed positions and constructing the jet grouting pile (1) and the underground continuous wall (2); using the double pipe method to construct the high-pressure jet grouting water-stopping pile, firstly drilling holes by means of a geological small-diameter drilling rig, inserting the grouting pipe into the hole, and then using a high-pressure grouting pump to spray cement slurry from a nozzle, rotating and lifting while spraying, and finally forming a cylindrical consolidation body in the soil; controlling the deviation between the hole position and the designed position to be no more than 50 mm; and controlling the distance between the spray hole and the high-pressure grouting pump to be no more than 50 mm; and inserting the pipe while drilling the hole. During the pipe insertion process, in order to prevent mud and sand from clogging the nozzle, a method of injecting water while inserting the pipe is adopted, and the water pressure is controlled not to exceed 1 MPa; The jet grouting piles are interlocked with each other. After the strength of the jet grouting piles meets the requirements, a cap beam (3) and a concrete top plate are arranged on the top of the piles, and the jet grouting piles (1) are connected to the underground continuous wall (2) through a connecting beam (7) to form a whole. Step (4): construct a sand well for drainage and consolidation and a semicircular drainage pipe. First, dig out the location of the sand well and fill it with gravel and crushed stone. When installing the water tank, set it downward along the depth of 5 meters to ensure the permeability and density of the sand well. At the same time, set a semicircular drainage pipe in the sand well and a pressure water level gauge in the sand well. When the pressure water level gauge exceeds the set threshold, insert the pumping pipe into the semicircular drainage pipe and use the water pump to pump water. By reducing the water head on the side of the sand well for drainage and consolidation, the double-row pile support is stabilized. When the pressure water level gauge value is lower than the threshold, cover the semicircular drainage pipe to protect its plug hole. Step (5): After the foundation pit construction is completed, concrete is poured back into the backwater trough. After the backwater trough is filled with concrete, the reverse setting is conducive to forming an enlarged head in the backwater trough. Under the reverse extrusion of the backwater trough, the overflowing concrete is squeezed into the gravel and crushed stone pores of the first-drain and then-fixed sand well, so that the first-drain and then-fixed sand well is consolidated, and finally a three-layer water-stop curtain support of the rotary jet pile, the first-drain and then-fixed sand well and the underground continuous wall is formed.

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