Variable-diameter jet grouting pile and lap joint method

Abstract

The invention relates to the technical field of civil engineering, and discloses a variable-diameter jet grouting pile and a lap joint method, the variable-diameter jet grouting pile comprises a jet grouting mechanism, the jet grouting mechanism comprises a jet grouting unit, and an adjusting unit is arranged on the surface of the jet grouting unit. According to the variable-diameter jet grouting pile and the lap joint method, a sliding block and a limiting block are adjusted through a second electric telescopic rod, a threaded sleeve block and a sliding adjusting block are driven, accurate adjustment of the diameter of the jet grouting pile is achieved, the construction efficiency and quality are improved, the direction of a jet grouting pipe is variable, replacement of a flow limiting opening is simplified, and accurate control over the diameter is ensured; taking a rotary jet grouting pile curtain with the depth of 30 m as an example, compared with a traditional method, by adjusting the lap joint width and the pile body diameter, the problem that bottom lap joint cannot be achieved is solved, meanwhile, the water stopping effect is greatly improved, the water stopping effect can be greatly improved by slightly increasing cost, and technical support and quality guarantee are provided for rotary jet grouting pile construction under the complex geological condition.

Description

Technical Field

[0001] The invention relates to the technical field of civil engineering, in particular to a variable diameter jet grouting pile and an overlapping method. Background Art

[0002] Jet grouting is a type of high-pressure jet grouting method. The high-pressure jet grouting method is to first use the drilling hole of the engineering drill as a guide hole, insert the grouting pipe with a special nozzle into the designed soil layer depth, and then eject the cement slurry from the nozzle in the form of a high-pressure flow to impact and cut the soil. Under the strong dynamic pressure of the high-pressure jet flow, the soil is destroyed in strength, and the soil particles are peeled off from the soil layer and mixed with the cement slurry to form a mixed slurry. Some fine particles emerge from the ground with the mixed slurry, and the remaining soil particles are regularly rearranged according to a certain slurry-soil ratio and mass size under the impact force, centrifugal force and gravity of the jet flow. In this way, the grouting is continuously ejected from the bottom to the top. After the mixed slurry solidifies, a consolidated body with a certain strength is formed in the soil layer. Jet jet piles are a widely used method in groundwater water-stopping projects. Adjacent piles overlap each other to form a water-stop curtain, including pure jet jet pile water-stop curtains and water-stop curtains formed by the combination of jet jet piles and other piles. The water-stopping effect of this type of water-stop curtain is closely related to the overlapping effect of adjacent piles. If the overlap is sufficient, the water-stopping effect is good. If the overlap is insufficient or there is no overlap at all, the water-stopping effect is not good. According to relevant specifications and industry practices, the minimum overlap width requirement is generally 150mm when the pile depth is not more than 10m, 250mm when the pile depth is 10-20m, and 350mm when the pile depth is 20m-30m. As the pile depth increases, the design overlap width also increases. The reason for this is mainly considered In actual construction, it is difficult to maintain consistent verticality of the piles. The allowable deviation of verticality in the specification is 1%. Taking the case of a pile depth of 30m and a design overlap of 350mm as an example, the distance deviation of the pile bottom with a 1% verticality deviation is 300mm. If two adjacent piles deviate by 1% in opposite directions in the curtain plane, the sum of the distance deviations of the pile bottoms is 600mm. In this case, the two piles cannot be overlapped, and theoretically a 250mm gap will be left. The water-stop curtain will have a leaking area here, seriously affecting the water-stopping effect of the entire water-stop curtain. If the overlap width is increased to 650mm for this purpose, the amount of work will be greatly increased, resulting in waste of materials and a substantial increase in construction costs. Therefore, a variable diameter rotary jet pile and an overlap method are urgently needed. Summary of the invention

[0003] The object of the present invention is to provide a variable diameter jet grouting pile and a lap joint method to solve the problems raised in the above background technology.

[0004] In order to solve the above technical problems, the present invention provides the following technical solutions: a variable diameter jet grouting pile and a lap method, comprising a jet grouting mechanism, the jet grouting mechanism comprising a jet grouting unit, and an adjustment unit is arranged on the surface of the jet grouting unit; The jet grouting unit comprises a jet grouting pipe, a nozzle is arranged on the surface of the jet grouting pipe, a drill bit is fixedly connected to the bottom end of the jet grouting pipe, a down-the-hole hammer is fixedly connected to the surface of one end of the drill bit away from the jet grouting pipe, a sliding frame is fixedly connected to the surface of the jet grouting pipe, an electric telescopic rod 1 is fixedly connected to the surface of the sliding frame, and a limiting ring is fixedly connected to the surface of the sliding frame; The adjusting unit is located on the surface of the jet grouting pipe and is used to adjust the injection diameter of the jet grouting pipe. The adjusting unit includes an electric telescopic rod 2, the telescopic end of the electric telescopic rod 2 is fixedly connected with a sliding block, and the end of the sliding block away from the electric telescopic rod 2 is fixedly connected with a limiting block. The adjusting unit also includes a threaded sleeve block, the surface of the threaded sleeve block is provided with threads, the surface of the threaded sleeve block is provided with a liquid outlet, the top of the threaded sleeve block is provided with a limiting groove 1, the surface of the threaded sleeve block is threadedly connected with a sliding adjustment block, the surface of the sliding adjustment block is provided with a limited flow port, the top of the sliding adjustment block is provided with a limiting groove 2, and the surface of the limiting block is clamped with the limiting groove 1.

[0005] As a preferred embodiment, the telescopic end of the electric telescopic rod 1 is fixedly connected with a clamping block, the surface of the clamping block is slidably connected to the limiting ring, and the surface of the clamping block is clamped with the limiting groove 2.

[0006] As a preferred embodiment, a sliding groove is opened on the inner wall of the sliding frame, the surface of the sliding groove is slidably connected to the limit block, the limit block sliding block passes through the sliding frame and is fixedly connected to the limit block, and the surface of the limit block is slidably connected to the inner wall of the sliding frame.

[0007] As a preferred implementation, the size of the limiting groove 1 is consistent with that of the sliding groove, and the inner wall of the threaded sleeve is rotatably connected to the jet grouting pipe.

[0008] As a preferred embodiment, the flow limiting openings are provided in four groups, and the four groups of flow limiting openings are distributed in a circular array around the surface of the sliding adjustment block, and the limiting grooves 2 are provided in four groups, and the four limiting grooves 2 are distributed in a circular array around the top of the sliding adjustment block.

[0009] As a preferred implementation, the following steps are included: S1: determining the overlap length: the overlap length should be determined according to geological conditions, pile diameter changes and design requirements; S2: Adjust grouting parameters: In the overlap area, the grouting parameters grouting pressure and grouting volume need to be properly adjusted to ensure that the grout can fully fill the gap between the piles. By increasing the grouting pressure or grouting volume, the permeability and consolidation effect of the grout can be improved; S3: Control the speed of jet grouting: In the overlapping area, slow down the speed of jet grouting to ensure that the slurry and soil are fully mixed; S4: Adjusting the diameter of the jet spray: During the overlapping process, the position of the sliding adjustment block is adjusted to replace the flow restriction ports of different sizes, thereby realizing the variable diameter of the pile hole. The design of the adjustment unit enables the pile hole diameter to be adjusted according to the variable diameter overlapping method of larger bottom and smaller top during overlapping; S5: Quality inspection and monitoring: After the overlap is completed, quality inspection and monitoring should be carried out to ensure that the overlap quality meets the design requirements. The methods of core drilling and water injection test should be used for inspection to ensure that the connection between the piles is tight and effective.

[0010] As a preferred implementation, in S3 controlling the rotary grouting lifting speed: in the overlapping area, since it is necessary to ensure the effective connection between adjacent piles, the mixing and stirring of the slurry and the soil must be sufficient, which requires that the rotary grouting lifting speed cannot be too fast, otherwise the slurry cannot fully penetrate into the soil, resulting in poor consolidation effect. On the contrary, appropriately slowing down the rotary grouting lifting speed can give the slurry enough time to mix with the soil, thereby improving the bearing capacity and stability of the pile.

[0011] As a preferred embodiment, in S4, the diameter of the jet grouting is adjusted: during the jet grouting process of the jet grouting piles, the jet grouting is carried out in three layers, namely, upper, middle and lower layers. For example, when the depth is fixed at 30m, the pile spacing is 650mm, the design overlap width of the upper section 10m is 250mm, and the diameter of the pile body of this section is 900mm, the design overlap width of the middle section 10m-20m is 450mm, and the diameter of the pile body of this section is 1100mm, and the design overlap width of the lower section 20m-30m is 650mm, and the diameter of the pile body of this section is 1300mm.

[0012] Compared with the prior art, the beneficial effects achieved by the present invention are: First, when the diameter of the rotary jet pile needs to be adjusted during use, the sliding block is driven to slide downward by the telescopic end of the electric telescopic rod 2, and the limiting block fixedly connected to the sliding block slides downward together, and reaches a limiting groove 1 with the same shape as the limiting block provided on the lower threaded sleeve block to be clamped with the limiting groove 1. At this time, when the jet grouting pipe is rotated, the clamping of the limiting block can drive the threaded sleeve block rotatably connected to the jet grouting pipe to rotate together. When the threaded sleeve block rotates, the sliding adjustment block threadedly connected to the surface thread will slide up and down. During the rotation of the threaded sleeve block, the liquid outlet will be aligned with the limiting ports of different diameters. The smaller the diameter of the limiting port, the smaller the spray diameter usually generated, and the width and penetration distance of the spray beam may be relatively large. On the contrary, the larger the diameter of the limiting port, The larger the generated jet diameter is, the smaller the width and penetration distance of the jet beam may be. A large diameter jet port will lead to a decrease in flow rate, and the diffusion effect of the fluid after leaving the jet port will also be weakened. The diameter of the jet pile can be limited by replacing flow limiting ports of different sizes, thereby achieving a change in the diameter of the jet pile. When the required flow limiting port is reached, the telescopic end of the electric telescopic rod 2 will drive the block to slide downward and dock with the limiting groove 2 at the top of the sliding adjustment block. Under the limiting action of the limiting ring, the sliding adjustment block and the threaded sleeve block become a whole and rotate together to fix the flow limiting port. The present invention improves the accuracy and flexibility of the diameter adjustment of the jet pile, and also significantly enhances the construction efficiency and quality, providing strong technical support for the construction of jet piles under complex geological conditions.

[0013] Second, when the present invention is in use, the jet grouting pipe can change direction conveniently. This feature makes the device flexible in operation. During the construction process, the operator can adjust the rotation direction of the jet grouting pipe according to actual needs to ensure that the slurry can be accurately sprayed to the predetermined position. In addition, the ability to change direction makes the replacement of the flow limiting port extremely simple. The operator can freely select and fix flow limiting ports of different diameters without complicated operating steps to adapt to different construction requirements and geological conditions. This design not only greatly improves the construction efficiency and reduces the difficulty of operation, but also ensures the precise control of the diameter of the rotary jet pile, providing a solid guarantee for the quality of the project.

[0014] Third, the present invention takes a 30m deep jet grouting pile curtain as an example. According to the general design idea method 1, if the jet grouting pile diameter is 1000mm, the design overlap width is 350mm, and the pile spacing is 650mm, there will be a large number of leakage areas at the bottom of this curtain. If this problem is overcome by increasing the overlap design width, method 2, the design method is adjusted to a depth of 30m, a pile diameter of 1000mm, a design overlap width of 650mm, and a pile spacing of 350mm. The overlap method of the present invention is also 30 m depth, 650mm pile spacing, the design overlap width of the upper section 10m is 250mm, then the pile diameter of this section is 900mm, the design overlap width of the middle section 10m-20m is 450mm, then the pile diameter of this section is 1100mm, the design overlap width of the lower section 20m-30m is 650mm, then the pile diameter of this section is 1300mm. For the same 22750mm length of the water-stop curtain, the volume of the jet grouting piles used by the three methods is calculated to be 825m 3 、1531m 3 and 1020m 3 The overlap method of the present invention has 195m more pile than the pile of method 1. 3 , i.e. 23.6%; the overlap method of the present invention is 511m less than that of the second method 3 , that is 50%. The overlapping method of the present invention uses 23.6% more engineering workload than method one, but can avoid the problem of bottom overlap, and can greatly improve the water-stopping effect of the water-stop curtain. The overlapping method of the present invention and method two can both avoid the problem of bottom overlap, but the overlapping method of the present invention saves 50% of the engineering workload than method two. Therefore, the overlapping method of the present invention is the most effective method that combines quality and cost, and greatly improves the water-stopping effect while slightly increasing the cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the disassembly of part of the structure of the present invention; Figure 3 It is a schematic diagram of the internal structure of part of the present invention; Figure 4 It is a partial structural schematic diagram of the present invention; Figure 5 It is a schematic diagram of the partial structure disassembly of the present invention; Figure 6 It is a flow chart of the overlapping method of the present invention; Figure 7 This is a first schematic diagram of the overlapping effect of the present invention; Figure 8 This is a second schematic diagram of the overlapping effect of the present invention.

[0016] Legend: 1. Jet grouting mechanism; 10. Jet grouting unit; 1000. Jet grouting pipe; 1001. Sprinkler; 1002. Drill bit; 1003. Down-the-hole hammer; 1004. Sliding frame; 1005. Electric telescopic rod 1; 1006. Limiting ring; 1007. Slide; 1009. Block; 20. Adjustment unit; 2000. Electric telescopic rod 2; 2001. Sliding block; 2002. Limiting block; 2003. Threaded sleeve block; 2004. Liquid outlet; 2005. Limiting groove 1; 2006. Sliding adjustment block; 2007. Limiting groove 2; 2008. Flow limiting port. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Example

[0018] like Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 and Figure 8 As shown, the present invention provides a technical solution: a variable diameter jet grouting pile and a lap method, comprising a jet grouting mechanism 1, the jet grouting mechanism 1 comprising a jet grouting unit 10, and an adjustment unit 20 is arranged on the surface of the jet grouting unit 10; The jet grouting unit 10 includes a jet grouting pipe 1000, a nozzle 1001 is arranged on the surface of the jet grouting pipe 1000, a drill bit 1002 is fixedly connected to the bottom end of the jet grouting pipe 1000, a down-the-hole hammer 1003 is fixedly connected to the surface of the drill bit 1002 away from the jet grouting pipe 1000, a sliding frame 1004 is fixedly connected to the surface of the jet grouting pipe 1000, an electric telescopic rod 1005 is fixedly connected to the surface of the sliding frame 1004, and a limiting ring 1006 is fixedly connected to the surface of the sliding frame 1004; The adjusting unit 20 is located on the surface of the jet grouting pipe 1000 and is used to adjust the injection diameter of the jet grouting pipe 1000. The adjusting unit 20 includes an electric telescopic rod 2000, the telescopic end of the electric telescopic rod 2000 is fixedly connected with a sliding block 2001, and the end of the sliding block 2001 away from the electric telescopic rod 2000 is fixedly connected with a limiting block 2002. The adjusting unit 20 also includes a threaded sleeve 2003, the surface of the threaded sleeve 2003 is provided with a thread, the surface of the threaded sleeve 2003 is provided with a liquid outlet 2004, the top of the threaded sleeve 2003 is provided with a limiting groove 1 2005, the surface of the threaded sleeve 2003 is threadedly connected with a sliding adjustment block 2006, the surface of the sliding adjustment block 2006 is provided with a limiting flow port 2008, the top of the sliding adjustment block 2006 is provided with a limiting groove 2007, and the surface of the limiting block 2002 is clamped with the limiting groove 1 2005.

[0019] By integrating the jet spray unit 10 and the adjustment unit 20, the jet diameter of the jet grouting pipe 1000 is flexibly adjusted. The jet spray unit 10 includes the jet grouting pipe 1000 and the nozzle 1001 thereon, as well as a drill bit 1002 and a down-the-hole hammer 1003 for breaking the ground and drilling. At the same time, the jet grouting pipe 1000 is also fixed with a sliding frame 1004, an electric telescopic rod 1005 and a limit ring 1006. The adjustment unit 20 uses the electric telescopic rod 2000 to drive the sliding block 2001 and the limit block 2002 to contact the limit groove 1005 of the threaded sleeve block 2003. The threaded sleeve 2003 can rotate with the jet grouting pipe 1000, and then drive the sliding adjustment block 2006 to slide up and down through the threaded connection to select the flow limiting port 2008 of different diameters to control the injection diameter. The limit groove 2007 of the sliding adjustment block 2006 is docked with the block 1009 of the electric telescopic rod 1005 to ensure the stability of the sliding adjustment block 2006. The whole mechanism is exquisitely designed and easy to operate, which effectively improves the flexibility and efficiency of the jet grouting pile construction. The surfaces of the electric telescopic rod 2000 and the electric telescopic rod 1005 are provided with protective shells.

[0020] The telescopic end of the electric telescopic rod 1005 is fixedly connected with a clamping block 1009 , the surface of the clamping block 1009 is slidably connected to the limiting ring 1006 , and the surface of the clamping block 1009 is clamped with the limiting groove 2007 .

[0021] The telescopic end of the electric telescopic rod 1005 is fixedly connected to a block 1009, and the block 1009 can slide on the surface of the limit ring 1006. Through the telescopic action of the electric telescopic rod 1005, the block 1009 can further stabilize and adjust the position of the sliding adjustment block 2006 under the constraint of the limit ring 1006, thereby enhancing the stability and reliability of the entire adjustment unit 20, and ensuring the accuracy of the injection diameter adjustment of the jet grouting pipe 1000 and the construction efficiency.

[0022] The inner wall of the sliding frame 1004 is provided with a sliding groove 1007 , the surface of the sliding groove 1007 is slidably connected to the limit block 2002 , the sliding block 2001 penetrates the sliding frame 1004 and is fixedly connected to the limit block 2002 , and the surface of the limit block 2002 is slidably connected to the inner wall of the sliding frame 1004 .

[0023] The inner wall of the sliding frame 1004 is designed with a slide groove 1007, which provides a sliding track for the limit block 2002. The limit block 2002 is fixedly connected to the telescopic end of the electric telescopic rod 2000 through the sliding block 2001, and the limit block 2002 can slide smoothly in the slide groove 1007. This design not only ensures that the limit block 2002 can move stably and accurately under the drive of the electric telescopic rod 2000, but also enhances the stability and control accuracy of the entire rotary spraying mechanism during the adjustment process through the guiding effect of the sliding frame 1004 on the limit block 2002, providing a solid foundation for the adjustment of the injection diameter of the jet grouting pipe 1000.

[0024] The size of the limiting groove 2005 is consistent with that of the sliding groove 1007, and the inner wall of the threaded sleeve block 2003 is rotatably connected to the jet grouting pipe 1000.

[0025] The size of the limiting groove 1 2005 is precisely designed to match the slide groove 1007. When the limiting block 2002 is driven by the electric telescopic rod 2000 to slide downward and engage with the limiting groove 1 2005 provided by the threaded sleeve 2003, the threaded sleeve 2003 can smoothly rotate along the outer wall of the jet grouting pipe 1000 when the jet grouting pipe 1000 rotates. The cooperation between the limiting block 2002 and the slide groove 1007 ensures the stability of the threaded sleeve 2003 during the rotation process. The rotation connection mode between the inner wall of the threaded sleeve 2003 and the jet grouting pipe 1000 not only realizes the free rotation of the jet grouting pipe 1000 during operation, but also realizes the precise adjustment of the injection diameter through the threaded connection between the threaded sleeve 2003 and the sliding adjustment block 2006, thereby improving the flexibility and efficiency of the rotary spraying mechanism 1 in construction.

[0026] There are four groups of flow limiting openings 2008 , which are distributed in a circular array around the surface of the sliding adjustment block 2006 . There are four limiting grooves 2007 , which are distributed in a circular array around the top of the sliding adjustment block 2006 .

[0027] The design of the sliding adjustment block 2006 is ingenious, and four groups of flow limiting ports 2008 are distributed in a circular array on its surface. This layout allows flow limiting ports 2008 of different diameters to be selected according to actual needs when adjusting the injection diameter, thereby achieving fine control of the injection flow rate. At the same time, four limit grooves 2007 are also arranged in a circular array on the top of the sliding adjustment block 2006. These limit grooves 2007 cooperate with the block 1009 of the electric telescopic rod 1005 to ensure the stability and accuracy of the sliding adjustment block 2006 during the adjustment process. In the process of adjusting the hole position, the jet grouting pipe 1000 can be controlled to rotate 90 degrees each time to correspond to the hole position. This design not only improves the flexibility of the rotary spraying mechanism 1, but also greatly enhances the construction efficiency and the accuracy of the injection effect.

[0028] A variable diameter jet grouting pile overlap method comprises the following steps: S1: determining the overlap length: the overlap length should be determined according to geological conditions, pile diameter changes and design requirements; S2: Adjust grouting parameters: In the overlap area, the grouting parameters grouting pressure and grouting volume need to be properly adjusted to ensure that the grout can fully fill the gap between the piles. By increasing the grouting pressure or grouting volume, the permeability and consolidation effect of the grout can be improved; S3: Control the speed of jet grouting: In the overlap area, slow down the speed of jet grouting to ensure that the slurry is fully mixed with the soil; too fast a lifting speed may cause the slurry to fail to consolidate fully, affecting the overall performance of the pile; S4: Adjusting the diameter of the jet spray: During the overlapping process, the position of the sliding adjustment block 2006 is adjusted to replace the flow restriction orifices 2008 of different sizes, thereby realizing the variable diameter of the pile hole. The design of the adjustment unit 20 enables the pile hole diameter to be adjusted according to the variable diameter overlapping method of the lower larger and the upper smaller during overlapping; S5: Quality inspection and monitoring: After the overlap is completed, quality inspection and monitoring should be carried out to ensure that the overlap quality meets the design requirements. The methods of core drilling and water injection test should be used for inspection to ensure that the connection between the piles is tight and effective.

[0029] In S3 controlling the rotary grouting lifting speed: in the overlap area, since it is necessary to ensure the effective connection between adjacent piles, the mixing of the slurry and the soil must be sufficient, which requires that the rotary grouting lifting speed cannot be too fast, otherwise the slurry cannot fully penetrate into the soil, resulting in poor consolidation effect. On the contrary, appropriately slowing down the rotary grouting lifting speed can give the slurry enough time to mix with the soil, thereby improving the bearing capacity and stability of the pile.

[0030] In S4, adjust the diameter of the jet grouting: during the jet grouting process of the jet grouting piles, the jet grouting is carried out in three layers: upper, middle and lower. For example, when the depth is fixed at 30m, the pile spacing is 650mm, the design overlap width of the upper section 10m is 250mm, and the diameter of the pile body of this section is 900mm. The design overlap width of the middle section 10m-20m is 450mm, and the diameter of the pile body of this section is 1100mm. The design overlap width of the lower section 20m-30m is 650mm, and the diameter of the pile body of this section is 1300mm.

[0031] Taking a 30m deep jet grouting pile curtain as an example, according to the general design idea method 1, if the jet grouting pile diameter is 1000mm, the design overlap width is 350mm, and the pile spacing is 650mm, there will be a large number of leakage areas at the bottom of this curtain. If this problem is overcome by increasing the overlap design width, method 2, the design method is adjusted to a depth of 30m, a pile diameter of 1000mm, a design overlap width of 650mm, and a pile spacing of 350mm. Using the overlap method of the present invention, the same is a depth of 30m, a pile spacing of 650mm, a design overlap width of 250mm for the upper section 10m, and a pile diameter of 900mm for this section, a design overlap width of 450mm for the middle section 10m-20m, and a pile diameter of 1100mm for this section, and a design overlap width of 650mm for the lower section 20m-30m, and a pile diameter of 1100mm for this section. The diameter is 1300mm. For the water-stop curtain with the same length of 22750mm, the volumes of the rotary jet piles used in the three methods are calculated to be 825m3, 1531m3 and 1020m3 respectively. The overlapping method of the present invention has 195m3 more piles than method one, i.e. 23.6% more; the overlapping method of the present invention has 511m3 less than method two, i.e. 50%. The overlapping method of the present invention uses 23.6% more engineering volume than method one, but can avoid the problem of bottom overlapping, which can greatly improve the water-stopping effect of the water-stop curtain. The overlapping method of the present invention and method two can both avoid the problem of bottom overlapping, but the overlapping method of the present invention saves 50% of the engineering volume than method two. Therefore, the overlapping method of the present invention is the most effective method that combines quality and cost, and greatly improves the water-stopping effect while slightly increasing the cost.

[0032] Working principle: when the diameter of the jet grouting pile needs to be adjusted during use, the telescopic end of the electric telescopic rod 2000 drives the sliding block 2001 to slide downward, and the limit block 2002 fixedly connected to the sliding block 2001 slides downward together, and reaches the limit groove 2005 of the same shape as the limit block 2002 set on the threaded sleeve 2003 below, and is engaged with the limit groove 2005. At this time, the rotating jet grouting pipe 1000 can drive the threaded sleeve 2003 to rotate together through the engagement of the limit block 2002, and the sliding adjustment block 2006 connected to the surface thread thread when the threaded sleeve 2003 rotates up and down Sliding, during the rotation of the threaded sleeve 2003, the liquid outlet 2004 will be aligned with the flow limiting ports 2008 of different diameters. The smaller the diameter of the flow limiting port 2008, the smaller the jet diameter is usually, and the width and penetration distance of the jet beam may be relatively large. On the contrary, the larger the diameter of the flow limiting port 2008, the larger the jet diameter may be, and the width and penetration distance of the jet beam may be relatively small. A large-diameter jet port will lead to a lower flow rate, and the diffusion effect of the fluid after leaving the jet port will also be weakened. By replacing the flow limiting ports 2008 of different sizes to limit the diameter of the jet grouting pile, the diameter of the jet grouting pile can be changed. Before use The adjustment is performed in advance. When the required flow restriction port 2008 is reached, the telescopic end of the electric telescopic rod 2000 will drive the clamping block 1009 to slide downward and engage with the limiting groove 2007 at the top of the sliding adjustment block 2006. Under the limiting action of the limiting ring 1006, the sliding adjustment block 2006 and the threaded sleeve block 2003 become a whole and rotate together to fix the flow restriction port 2008. The present invention improves the accuracy and flexibility of the diameter adjustment of the jet grouting pile, and also significantly enhances the construction efficiency and quality, providing strong technical support for the construction of jet grouting piles under complex geological conditions, and the jet grouting pipe 1000 can be conveniently The device can be changed in direction at will. This feature makes the device flexible in operation. During the construction process, the operator can adjust the rotation direction of the jet grouting pipe 1000 according to actual needs to ensure that the slurry can be accurately sprayed to the predetermined position. The ability to change direction makes the replacement of the flow restriction port 2008 extremely simple. The operator can freely select and fix the flow restriction port 2008 of different diameters without complicated operation steps to adapt to different construction requirements and geological conditions. This design not only greatly improves the construction efficiency and reduces the difficulty of operation, but also ensures the precise control of the diameter of the jet grouting pile, providing a solid guarantee for the quality of the project. In addition, the present invention takes a 30m deep jet grouting pile curtain as an example. According to the general design idea method 1, if the jet grouting pile diameter is 1000mm, the design overlap width is 350mm, and the pile spacing is 650mm, there will be a large number of leakage areas at the bottom of the curtain. If this problem is overcome by increasing the overlap design width, method 2, the design method is adjusted to a depth of 30m, a pile diameter of 1000mm, a design overlap width of 650mm, and a pile spacing of 350mm. The overlap method of the present invention is also 30 m depth, 650mm pile spacing, the design overlap width of the upper section 10m is 250mm, then the pile diameter of this section is 900mm, the design overlap width of the middle section 10m-20m is 450mm, then the pile diameter of this section is 1100mm, the design overlap width of the lower section 20m-30m is 650mm, then the pile diameter of this section is 1300mm. For the same 22750mm length of the water-stop curtain, the volume of the jet grouting piles used by the three methods is calculated to be 825m 3 、1531m 3 and 1020m 3 The overlap method of the present invention has 195m more pile than the pile of method 1. 3 , i.e. 23.6%; the overlap method of the present invention is 511m less than that of the second method 3 , that is 50%. The overlapping method of the present invention uses 23.6% more engineering workload than method one, but can avoid the problem of bottom overlap, and can greatly improve the water-stopping effect of the water-stop curtain. The overlapping method of the present invention and method two can both avoid the problem of bottom overlap, but the overlapping method of the present invention saves 50% of the engineering workload than method two. Therefore, the overlapping method of the present invention is the most effective method that combines quality and cost, and greatly improves the water-stopping effect while slightly increasing the cost.

[0033] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and alterations may be made to the embodiments without departing from the principles and spirit thereof, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A variable diameter jet grouting pile, comprising a jet grouting mechanism (1), characterized in that: The rotary spraying mechanism (1) comprises a rotary spraying unit (10), and an adjustment unit (20) is provided on the surface of the rotary spraying unit (10); The jet grouting unit (10) comprises a jet grouting pipe (1000), a nozzle (1001) is arranged on the surface of the jet grouting pipe (1000), a drill bit (1002) is fixedly connected to the bottom end of the jet grouting pipe (1000), a down-the-hole hammer (1003) is fixedly connected to the surface of one end of the drill bit (1002) away from the jet grouting pipe (1000), a sliding frame (1004) is fixedly connected to the surface of the jet grouting pipe (1000), an electric telescopic rod (1005) is fixedly connected to the surface of the sliding frame (1004), and a limiting ring (1006) is fixedly connected to the surface of the sliding frame (1004); The adjustment unit (20) is located on the surface of the jet grouting pipe (1000) and is used to adjust the jetting diameter of the jet grouting pipe (1000). The adjustment unit (20) comprises an electric telescopic rod (2000), the telescopic end of the electric telescopic rod (2000) being fixedly connected to a sliding block (2001), and one end of the sliding block (2001) away from the electric telescopic rod (2000) being fixedly connected to a limiting block (2002). The adjustment unit (20) further comprises a threaded sleeve (2003), and the threaded sleeve (2003) The surface of the threaded sleeve (2003) is provided with a thread, the surface of the threaded sleeve (2003) is provided with a liquid outlet (2004), the top of the threaded sleeve (2003) is provided with a limiting groove (2005), the surface of the threaded sleeve (2003) is threadedly connected with a sliding adjustment block (2006), the surface of the sliding adjustment block (2006) is provided with a limiting flow port (2008), the top of the sliding adjustment block (2006) is provided with a limiting groove (2007), and the surface of the limiting block (2002) is snap-fitted with the limiting groove (2005).

2. The variable diameter jet grouting pile according to claim 1, characterized in that: The telescopic end of the first electric telescopic rod (1005) is fixedly connected with a clamping block (1009), the surface of the clamping block (1009) is slidably connected to a limiting ring (1006), and the surface of the clamping block (1009) is clamped with a second limiting groove (2007).

3. The variable diameter jet grouting pile according to claim 1, characterized in that: The inner wall of the sliding frame (1004) is provided with a sliding groove (1007), the surface of the sliding groove (1007) is slidably connected to the limit block (2002), the sliding block (201) of the limit block (2002) penetrates the sliding frame (1004) and is fixedly connected to the limit block (2002), and the surface of the limit block (2002) is slidably connected to the inner wall of the sliding frame (1004).

4. The variable diameter jet grouting pile according to claim 1, characterized in that: The size of the limiting groove 1 (2005) is consistent with that of the sliding groove (1007), and the inner wall of the threaded sleeve (2003) is rotatably connected to the jet grouting pipe (1000).

5. The variable diameter jet grouting pile according to claim 1, characterized in that: The flow limiting openings (2008) are provided in four groups, and the four groups of flow limiting openings (2008) are distributed in a circular array around the surface of the sliding adjustment block (2006); the limiting grooves (2007) are provided in four groups, and the four limiting grooves (2007) are distributed in a circular array around the top of the sliding adjustment block (2006).

6. A variable diameter jet grouting pile overlapping method, based on the variable diameter jet grouting pile according to claim 1, characterized in that: The following steps are involved: S1: Determine the lap length: The lap length should be determined based on geological conditions, pile diameter changes and design requirements; S2: Adjust grouting parameters: In the overlap area, the grouting parameters grouting pressure and grouting volume need to be properly adjusted to ensure that the grout can fully fill the gap between the piles. By increasing the grouting pressure or grouting volume, the permeability and consolidation effect of the grout can be improved; S3: Control the speed of jet grouting: In the overlapping area, slow down the speed of jet grouting to ensure that the slurry and soil are fully mixed; S4: adjusting the diameter of the jet spray: during the overlapping process, the position of the sliding adjustment block (2006) is adjusted to replace the flow restriction ports of different sizes, thereby realizing the variable diameter of the pile hole. The design of the adjustment unit (2000) enables the pile hole diameter to be adjusted according to the variable diameter overlapping method of larger bottom and smaller top during overlapping; S5: Quality inspection and monitoring: After the overlap is completed, quality inspection and monitoring should be carried out to ensure that the overlap quality meets the design requirements. The methods of core drilling and water injection test should be used for inspection to ensure that the connection between the piles is tight and effective.

7. A variable diameter jet grouting pile overlapping method according to claim 6, characterized in that: In S3 controlling the rotary grouting lifting speed: in the overlap area, since it is necessary to ensure the effective connection between adjacent piles, the mixing of the slurry and the soil must be sufficient, which requires that the rotary grouting lifting speed cannot be too fast, otherwise the slurry cannot fully penetrate into the soil, resulting in poor consolidation effect. On the contrary, appropriately slowing down the rotary grouting lifting speed can give the slurry enough time to mix with the soil, thereby improving the bearing capacity and stability of the pile.

8. A variable diameter jet grouting pile overlapping method according to claim 6, characterized in that: In S4, adjust the diameter of the jet grouting: during the jet grouting process of the jet grouting piles, the jet grouting is carried out in three layers: upper, middle and lower. For example, when the depth is fixed at 30m, the pile spacing is 650mm, the design overlap width of the upper section 10m is 250mm, and the diameter of the pile body of this section is 900mm. The design overlap width of the middle section 10m-20m is 450mm, and the diameter of the pile body of this section is 1100mm. The design overlap width of the lower section 20m-30m is 650mm, and the diameter of the pile body of this section is 1300mm.

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