Variable diameter jet grouting pile and splicing method

Abstract

The application relates to the technical field of civil engineering, and discloses a variable-diameter rotary jet grouting pile and a lapping method, which comprises a rotary jet mechanism, the rotary jet mechanism comprises a rotary jet unit, and the surface of the rotary jet unit is provided with an adjusting unit. The variable-diameter rotary jet grouting pile and the lapping method, the electric telescopic rod two adjusting sliding blocks and the limiting blocks drive the threaded sleeve blocks and the sliding adjusting blocks, the diameter of the rotary jet grouting pile is accurately adjusted, the construction efficiency and quality are enhanced, the direction of the jet grouting pipe can be changed, the replacement of the flow-limiting port is simplified, the diameter is accurately controlled, and, taking a 30m deep rotary jet grouting pile curtain as an example, compared with a traditional method, the lapping width and the pile diameter are adjusted, the problem that the bottom cannot be lapped is avoided, meanwhile, the water stopping effect is greatly improved, a small amount of cost increase can greatly improve the water stopping effect, and technical support and quality guarantee are provided for rotary jet grouting pile construction under complex geological conditions.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of civil engineering, in particular to a variable-diameter rotary jet grouting pile and a lapping method. BACKGROUND

[0002] The rotary jet grouting pile is a kind of high-pressure jet grouting method. The high-pressure jet grouting method is to first drill a guide hole by using an engineering drill, insert a grouting pipe with a special nozzle into the designed soil layer depth, and then jet out the cement slurry from the nozzle in the form of high-pressure flow. The soil is impacted and cut, and the soil particles are stripped from the soil layer under the action of the strong dynamic pressure of the high-pressure jet flow, etc. The soil particles are mixed with the cement slurry to form a mixed slurry. A part of the fine particles is ejected out of the ground with the mixed slurry, and the remaining soil particles are regularly rearranged according to the slurry-soil ratio and mass size under the action of the jet flow impact force, centrifugal force and gravity. The mixed slurry is continuously jetted and grouted from bottom to top, and the mixed slurry is solidified to form a consolidated body with a certain strength in the soil layer.

[0003] The rotary jet grouting pile is a method widely used in underground water stopping engineering. Adjacent piles are lapped to form a water stopping curtain, including a pure rotary jet grouting pile water stopping curtain and a water stopping curtain formed by combining rotary jet grouting piles with other piles. The water stopping effect of this type of water stopping curtain and the lapping effect of adjacent piles are closely related. If the lapping is sufficient, the water stopping effect is good. If the lapping is insufficient or there is no lapping at all, the water stopping effect is poor. According to relevant specifications and industry practices, the minimum lapping width is generally 150mm when the pile depth is not greater than 10m, 250mm when the pile depth is 10-20m, and 350mm when the pile depth is 20-30m. As the pile depth increases, the design lapping width also increases. The reason for this is mainly that the verticality of the pile is difficult to maintain consistent in actual construction. The verticality deviation allowed in the specification is 1%. Taking the case of a 30m deep pile with a design lapping width of 350mm as an example, the distance deviation of the pile bottom due to a 1% verticality deviation is 300mm. If the adjacent two piles deviate 1% in opposite directions in the curtain plane, the distance deviation of the pile bottoms is 600mm. In this case, the two piles cannot be lapped, and theoretically a 250mm gap will be left, which will cause a leakage area in the water stopping curtain, seriously affecting the water stopping effect of the entire water stopping curtain. If the lapping width is increased to 650mm to solve this problem, it will greatly increase the engineering quantity, resulting in waste of materials and a significant increase in cost. Therefore, there is an urgent need for a variable-diameter rotary jet grouting pile and a lapping method. SUMMARY

[0004] The present application aims to provide a variable-diameter rotary jet grouting pile and a lapping method to solve the problems raised in the background.

[0005] In order to solve the above technical problems, the present application provides the following technical solutions: A variable diameter rotary jet pile and a lapping method, comprising a rotary jet mechanism, the rotary jet mechanism comprises a rotary jet unit, the surface of the rotary jet unit is provided with an adjusting unit;

[0006] The rotary jet unit comprises a jet grouting pipe, the surface of the jet grouting pipe is provided with a spray head, the bottom end of the jet grouting pipe is fixedly connected with a drill bit, the surface of the end of the drill bit away from the jet grouting pipe is fixedly connected with a down-the-hole hammer, the surface of the jet grouting pipe is fixedly connected with a sliding frame, the surface of the sliding frame is fixedly connected with an electric telescopic rod one, and the surface of the sliding frame is fixedly connected with a limiting ring.

[0007] The adjusting unit is located on the surface of the jet grouting pipe and is used for adjusting the jet diameter of the jet grouting pipe, the adjusting unit comprises an electric telescopic rod two, the telescopic end of the electric telescopic rod two is fixedly connected with a sliding block, the end of the sliding block away from the electric telescopic rod two is fixedly connected with a limiting block, the adjusting unit further comprises 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 end of the threaded sleeve block is provided with a limiting groove one, the surface of the threaded sleeve block is threadedly connected with a sliding adjusting block, the surface of the sliding adjusting block is provided with a flow limiting port, the top end of the sliding adjusting block is provided with a limiting groove two, and the surface of the limiting block is connected with the limiting groove one.

[0008] As a preferred embodiment, the telescopic end of the electric telescopic rod one is fixedly connected with a clamping block, the surface of the clamping block is slidingly connected with the limiting ring, and the surface of the clamping block is connected with the limiting groove two.

[0009] As a preferred embodiment, the inner wall of the sliding frame is provided with a sliding groove, the surface of the sliding groove is slidingly connected with the limiting block, the limiting block is fixedly connected with the limiting block through the sliding block, and the surface of the limiting block is slidingly connected with the inner wall of the sliding frame.

[0010] As a preferred embodiment, the size of the limiting groove one is consistent with the size of the sliding groove, and the inner wall of the threaded sleeve block is rotationally connected with the jet grouting pipe.

[0011] As a preferred embodiment, the flow limiting port is provided with four groups, the four groups of flow limiting ports are distributed in a circumferential array around the surface of the sliding adjusting block, the limiting groove two is provided with four, and the four limiting grooves two are distributed in a circumferential array around the top end of the sliding adjusting block.

[0012] As a preferred embodiment, the method comprises the following steps: S1: determining the lapping length: the lapping length should be determined according to the geological conditions, the pile diameter change and the design requirements;

[0013] S2: Adjust the grouting parameters: In the overlapping area, the grouting parameters such as grouting pressure and grouting quantity need to be adjusted appropriately to ensure that the slurry can fully fill the gap between the pile bodies, and by increasing the grouting pressure or grouting quantity, the permeability and consolidation effect of the slurry can be improved;

[0014] S3: Control the lifting speed of rotary jet grouting: In the overlapping area, the lifting speed of rotary jet grouting is slowed down to ensure that the slurry is fully mixed and stirred with the soil;

[0015] S4: Adjust the diameter of rotary jet grouting: During the overlapping process, the position of the sliding adjustment block is adjusted to replace the flow limiting port of different sizes, thereby realizing the variable diameter of the pile hole, and the design of the adjustment unit enables the diameter of the pile hole to be adjusted according to the variable diameter overlapping method of decreasing from top to bottom during overlapping;

[0016] S5: Quality detection and monitoring: After the overlapping is completed, quality detection and monitoring should be carried out to ensure that the overlapping quality meets the design requirements, and drilling core and water injection test methods are used for detection to ensure that the connection between the pile bodies is tight and effective.

[0017] As a preferred embodiment, in S3 control the lifting speed of rotary jet grouting: In the overlapping area, since the effective connection between adjacent pile bodies needs to be ensured, the mixing and stirring of the slurry with the soil must be sufficient, which requires that the lifting speed of rotary jet grouting cannot be too fast, otherwise the slurry cannot fully penetrate into the soil, resulting in poor consolidation effect, on the contrary, slowing down the lifting speed of rotary jet grouting appropriately can give the slurry enough time to mix with the soil, thereby improving the bearing capacity and stability of the pile body.

[0018] As a preferred embodiment, in S4 adjust the diameter of rotary jet grouting: During the rotary jet grouting process of rotary jet piles, three layers of upper, middle and lower are divided for rotary jet grouting, for example, when the fixed depth is 30m, the pile spacing is 650mm, the design overlapping width of the upper segment 10m is 250mm, then the diameter of this pile body is 900mm, the design overlapping width of the middle segment 10m-20m is 450mm, then the diameter of this pile body is 1100mm, and the design overlapping width of the lower segment 20m-30m is 650mm, then the diameter of this pile body is 1300mm.

[0019] Compared with the prior art, the beneficial effects achieved by the present application are:

[0020] First, when the present invention is in use and the diameter of the jet grouting pile needs to be adjusted, the sliding block is driven to slide downward by the telescopic end of the electric telescopic rod 2, and the limit block fixedly connected to the sliding block slides downward together, and reaches a limit groove 1 with the same shape as the limit block provided in the lower threaded sleeve to engage with the limit groove 1. At this time, when the jet grouting pipe is rotated, the threaded sleeve rotatably connected to the jet grouting pipe can be driven to rotate together through the engagement of the limit block. When the threaded sleeve rotates, the sliding adjustment block threadedly connected to the surface thread will slide up and down. During the rotation of the threaded sleeve, the liquid outlet will be aligned with the flow restriction ports of different diameters. The smaller the flow restriction port diameter, the smaller the jet diameter generally is, and the width and penetration distance of the jet beam may be relatively large. On the contrary, the larger the flow restriction port diameter, The larger the generated jet diameter may be, the smaller the width and penetration distance of the jet beam may be. 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. The diameter of the jet pile can be limited by replacing the 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 clamping 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.

[0021] Second, when the present invention is in use, the jet grouting pipe can change direction conveniently. This feature gives the device operational flexibility. 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 restriction port extremely simple. The operator can freely select and fix flow restriction ports of different diameters without complicated operating steps to adapt to different construction requirements and geological conditions. This design not only greatly improves construction efficiency and reduces operational difficulty, but also ensures precise control of the diameter of the jet grouting pile, providing a solid guarantee for project quality.

[0022] Third, the present application takes a 30m deep rotary jet pile curtain as an example. According to the general design idea and method, if the rotary jet pile diameter is 1000mm, the design overlap width is 350mm, and the pile spacing is 650mm, there will be a large amount of water leakage area at the bottom of the curtain. If the design width is increased to overcome this problem, method two, 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 application, with a depth of 30m and a pile spacing of 650mm, the design overlap width of the upper section 10m is 250mm, the pile diameter of this section is 900mm, the design overlap width of the middle section 10m-20m is 450mm, the pile diameter of this section is 1100mm, and the design overlap width of the lower section 20m-30m is 650mm, the pile diameter of this section is 1300mm. For the same 22750mm long water stop curtain, the volume of the rotary jet pile used by the three methods is calculated as 825m 3 , 1531m 3 , and 1020m 3 . The overlap method of the present application is 195m 3 more than the pile of method one, i.e. 23.6%; the overlap method of the present application is 511m 3 less than method two, i.e. 50%. The overlap method of the present application uses 23.6% more engineering quantity than method one, but can avoid the problem of not overlapping at the bottom and greatly improve the water stopping effect of the water stop curtain. The overlap method of the present application and method two can both avoid the problem of not overlapping at the bottom, but the overlap method of the present application saves 50% of the engineering quantity compared to method two. Therefore, the overlap method of the present application is the best method that combines quality and cost, with a small amount of cost increase and a significant improvement in water stopping effect. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a schematic diagram of the overall structure of the present application;

[0024] Figure 2 is a schematic diagram of the partial structure of the present application;

[0025] Figure 3 is a schematic diagram of the internal structure of the present application;

[0026] Figure 4 is a schematic diagram of the partial structure of the present application;

[0027] Figure 5 is a schematic diagram of the partial structure of the present application;

[0028] Figure 6 is a flowchart of the overlap method of the present application;

[0029] Figure 7 is a first schematic diagram of the overlap effect of the present application;

[0030] Figure 8 Second schematic diagram of the lap joint effect of the present application.

[0031] Legend:

[0032] 1, rotary spraying mechanism; 10, rotary spraying unit; 1000, jet grouting pipe; 1001, spray head; 1002, drill bit; 1003, down-the-hole hammer; 1004, sliding frame; 1005, electric telescopic rod one; 1006, limiting ring; 1007, sliding groove; 1009, clamping block;

[0033] 20, adjusting unit; 2000, electric telescopic rod two; 2001, sliding block; 2002, limiting block; 2003, threaded sleeve block; 2004, liquid outlet; 2005, limiting groove one; 2006, sliding adjusting block; 2007, limiting groove two; 2008, flow limiting port. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application. EMBODIMENT

[0035] As shown in Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 and Figure 8 , the present application provides a variable-diameter rotary spraying pile and a lap joint method, which comprises a rotary spraying mechanism 1, the rotary spraying mechanism 1 comprising a rotary spraying unit 10, the surface of the rotary spraying unit 10 being provided with an adjusting unit 20.

[0036] The rotary spraying unit 10 comprises a jet grouting pipe 1000, the surface of the jet grouting pipe 1000 being provided with a spray head 1001, the bottom end of the jet grouting pipe 1000 being fixedly connected with a drill bit 1002, the surface of the end of the drill bit 1002 away from the jet grouting pipe 1000 being fixedly connected with a down-the-hole hammer 1003, the surface of the jet grouting pipe 1000 being fixedly connected with a sliding frame 1004, the surface of the sliding frame 1004 being fixedly connected with an electric telescopic rod one 1005, and the surface of the sliding frame 1004 being fixedly connected with a limiting ring 1006.

[0037] The adjusting unit 20 is located on the surface of the jet grouting pipe 1000 and is used for adjusting the jetting diameter of the jet grouting pipe 1000. The adjusting unit 20 comprises an electric telescopic rod two 2000, the telescopic end of the electric telescopic rod two 2000 is fixedly connected with a sliding block 2001, the end, away from the electric telescopic rod two 2000, of the sliding block 2001 is fixedly connected with a limiting block 2002, the adjusting unit 20 further comprises a threaded sleeve block 2003, the surface of the threaded sleeve block 2003 is provided with threads, the surface of the threaded sleeve block 2003 is provided with a liquid outlet 2004, the top end of the threaded sleeve block 2003 is provided with a limiting groove one 2005, the surface of the threaded sleeve block 2003 is threadedly connected with a sliding adjusting block 2006, the surface of the sliding adjusting block 2006 is provided with a flow limiting opening 2008, the top end of the sliding adjusting block 2006 is provided with a limiting groove two 2007, and the surface of the limiting block 2002 is clamped with the limiting groove one 2005.

[0038] By integrating the rotary jetting unit 10 and the adjusting unit 20, the jetting diameter of the jet grouting pipe 1000 can be flexibly adjusted. The rotary jetting unit 10 comprises the jet grouting pipe 1000, the nozzles 1001 on the jet grouting pipe 1000, the drill bit 1002 and the down-the-hole hammer 1003 for breaking the soil and drilling. Meanwhile, the sliding frame 1004, the electric telescopic rod one 1005 and the limiting ring 1006 are fixed on the jet grouting pipe 1000. The adjusting unit 20 drives the sliding block 2001 and the limiting block 2002 by the electric telescopic rod two 2000, cooperates with the limiting groove one 2005 of the threaded sleeve block 2003, and makes the threaded sleeve block 2003 rotate with the jet grouting pipe 1000. Then, the threaded sleeve block 2003 drives the sliding adjusting block 2006 to slide up and down by the threaded connection, so as to select the flow limiting opening 2008 of different diameters to control the jetting diameter. The limiting groove two 2007 of the sliding adjusting block 2006 is connected with the clamping block 1009 of the electric telescopic rod one 1005, which ensures the stability of the sliding adjusting block 2006. The whole mechanism is designed precisely and is easy to operate, which effectively improves the flexibility and efficiency of the rotary jetting pile construction. The surfaces of the electric telescopic rod two 2000 and the electric telescopic rod one 1005 are provided with protective shells.

[0039] The telescopic end of the electric telescopic rod one 1005 is fixedly connected with the clamping block 1009, the surface of the clamping block 1009 is slidably connected with the limiting ring 1006, and the surface of the clamping block 1009 is clamped with the limiting groove two 2007.

[0040] The telescopic end of the electric telescopic rod one 1005 is fixedly connected with the clamping block 1009, which can slide on the surface of the limiting ring 1006. Through the telescopic action of the electric telescopic rod one 1005, the clamping block 1009 can further stabilize and adjust the position of the sliding adjusting block 2006 under the constraint of the limiting ring 1006, thereby enhancing the stability and reliability of the whole adjusting unit 20 and ensuring the accuracy and construction efficiency of the jetting diameter adjustment of the jet grouting pipe 1000.

[0041] The inner wall of the sliding frame 1004 is provided with a sliding groove 1007, the surface of the sliding groove 1007 is in sliding connection with the limiting block 2002, the sliding block 2001 penetrates the sliding frame 1004 and is fixedly connected with the limiting block 2002, and the surface of the limiting block 2002 is in sliding connection with the inner wall of the sliding frame 1004.

[0042] The inner wall of the sliding frame 1004 is designed to have the sliding groove 1007, which provides a sliding track for the limiting block 2002. The limiting block 2002 is fixedly connected with the telescopic end of the second electric telescopic rod 2000 through the sliding block 2001, and the limiting block 2002 can smoothly slide in the sliding groove 1007. Such a design not only ensures that the limiting block 2002 can stably and accurately move under the drive of the second electric telescopic rod 2000, but also enhances the stability and control accuracy of the whole rotary spraying mechanism during the adjustment process through the guiding effect of the sliding frame 1004 on the limiting block 2002, thereby providing a solid foundation for the adjustment of the spraying diameter of the spraying grouting pipe 1000.

[0043] The limiting groove one 2005 is consistent in size with the sliding groove 1007, and the inner wall of the threaded sleeve block 2003 is in rotary connection with the spraying grouting pipe 1000.

[0044] The limiting groove one 2005 is accurately designed to match the sliding groove 1007. When the limiting block 2002 is driven by the second electric telescopic rod 2000 to slide downward and is clamped with the limiting groove one 2005 opened in the threaded sleeve block 2003, the threaded sleeve block 2003 can smoothly rotate along the outer wall of the spraying grouting pipe 1000 when the spraying grouting pipe 1000 rotates, and the stability of the threaded sleeve block 2003 during rotation is ensured through the cooperation of the limiting block 2002 and the sliding groove 1007. The rotary connection between the inner wall of the threaded sleeve block 2003 and the spraying grouting pipe 1000 not only realizes the free rotation of the spraying grouting pipe 1000 during operation, but also realizes the accurate adjustment of the spraying diameter through the threaded connection between the threaded sleeve block 2003 and the sliding adjustment block 2006, thereby improving the flexibility and efficiency of the rotary spraying mechanism 1 during construction.

[0045] The flow limiting port 2008 is provided with four groups, and the four groups of flow limiting ports 2008 are distributed in a circumferential array around the surface of the sliding adjustment block 2006. The limiting groove two 2007 is provided with four, and the four limiting grooves two 2007 are distributed in a circumferential array around the top end of the sliding adjustment block 2006.

[0046] The design of the sliding adjustment block 2006 is unique, with four sets of flow-limiting openings 2008 arranged in a circular array on its surface. This layout allows for the selection of different diameters of flow-limiting openings 2008 according to actual needs when adjusting the jet diameter, thereby achieving fine control of the jet flow. At the same time, the top of the sliding adjustment block 2006 is also arranged in a circular array with four limiting grooves two 2007, which cooperate with the clamping block 1009 of the electric telescopic rod one 1005 to ensure the stability and accuracy of the sliding adjustment block 2006 during adjustment. During the adjustment of the hole position, the control jet grouting pipe 1000 is rotated by 90 degrees each time to correspond to the hole position. This design not only improves the flexibility of the rotary jet mechanism 1 adjustment, but also greatly enhances the construction efficiency and the precision of the jetting effect.

[0047] A variable-diameter rotary jet pile lapping method, comprising the following steps: S1: determining the lapping length: the lapping length should be determined according to the geological conditions, pile diameter change and design requirements;

[0048] S2: adjusting the grouting parameters: in the lapping area, the grouting parameters, grouting pressure and grouting volume, need to be adjusted appropriately to ensure that the slurry can fully fill the gap between the pile bodies. By increasing the grouting pressure or grouting volume, the permeability and consolidation effect of the slurry can be improved;

[0049] S3: controlling the rotary jet lifting speed: in the lapping area, the rotary jet lifting speed is slowed down to ensure that the slurry and soil are fully mixed and stirred; too fast lifting speed may result in insufficient consolidation of the slurry, affecting the overall performance of the pile body;

[0050] S4: adjusting the rotary jet diameter: during lapping, the position of the sliding adjustment block 2006 is adjusted to replace different sizes of flow-limiting openings 2008, thereby realizing the variable diameter of the pile hole. The design of the adjustment unit 20 allows the pile hole diameter to be adjusted according to the large-to-small variable-diameter lapping method during lapping;

[0051] S5: quality detection and monitoring: after lapping is completed, quality detection and monitoring should be carried out to ensure that the lapping quality meets the design requirements. Drilling core sampling and water injection testing methods are used for detection to ensure that the connection between the pile bodies is tight and effective.

[0052] In S3, control the rotary jet lifting speed: in the lapping area, since it is necessary to ensure effective connection between adjacent pile bodies, the mixing and stirring of the slurry and soil must be sufficient, which requires that the rotary jet lifting speed cannot be too fast, otherwise the slurry cannot fully penetrate into the soil, resulting in poor consolidation effect. On the contrary, slowing down the rotary jet lifting speed appropriately can give the slurry enough time to mix with the soil, thereby improving the bearing capacity and stability of the pile body.

[0053] In the S4 adjustment of the jet grouting diameter: during the jet grouting process of the jet grouting pile, the jet grouting is performed in three layers of upper, middle and lower layers. For example, when the fixed depth is 30 m, the pile spacing is 650 mm, the design overlap width of the upper section of 10 m is 250 mm, the pile diameter of this section is 900 mm, the design overlap width of the middle section of 10 m-20 m is 450 mm, the pile diameter of this section is 1100 mm, and the design overlap width of the lower section of 20 m-30 m is 650 mm, the pile diameter of this section is 1300 mm.

[0054] Taking a 30 m deep jet grouting pile curtain as an example, according to the general design idea and method one, if the jet grouting pile diameter is 1000 mm, the design overlap width is 350 mm, and the pile spacing is 650 mm, there will be a large amount of water leakage area at the bottom of the curtain. If the design width is increased to overcome this problem, method two, the design method is adjusted to a depth of 30 m, a pile diameter of 1000 mm, a design overlap width of 650 mm, and a pile spacing of 350 mm. According to the overlapping method of the present application, the depth is also 30 m, the pile spacing is 650 mm, the design overlap width of the upper section of 10 m is 250 mm, the pile diameter of this section is 900 mm, the design overlap width of the middle section of 10 m-20 m is 450 mm, the pile diameter of this section is 1100 mm, and the design overlap width of the lower section of 20 m-30 m is 650 mm, the pile diameter of this section is 1300 mm. For the same 22750 mm long water stop curtain, the volume of the jet grouting pile used by the three methods is calculated as 825 m3, 1531 m3 and 1020 m3 respectively. The overlapping method of the present application is 195 m3 more than the pile of method one, i.e. 23.6%; the overlapping method of the present application is 511 m3 less than method two, i.e. 50%. The overlapping method of the present application uses 23.6% more engineering quantity than method one, but can avoid the problem of not overlapping at the bottom and greatly improve the water stopping effect of the water stop curtain. The overlapping method of the present application and method two can avoid the problem of not overlapping at the bottom, but the overlapping method of the present application saves 50% of the engineering quantity compared with method two. Therefore, the overlapping method of the present application is the best method that combines quality and cost, which slightly increases the cost while greatly improves the water stopping effect.

[0055] Working principle: when the diameter of the rotary jet pile needs to be adjusted during use, the sliding block 2001 is driven downward by the telescopic end of the second electric telescopic rod 2000, and the limiting block 2002 fixedly connected with the sliding block 2001 is also slid downward and reaches the limiting groove I 2005 provided in the lower threaded sleeve block 2003, and the limiting groove I 2005 is clamped, at this time, the rotary jet grouting pipe 1000 is clamped by the threaded sleeve block 2003 through the clamping of the limiting block 2002, and the sliding adjusting block 2006 is slid up and down through the surface thread connection during the rotation of the threaded sleeve block 2003, and the liquid outlet 2004 is aligned with the different diameter flow limiting port 2008 during the rotation of the threaded sleeve block 2003, the smaller the diameter of the flow limiting port 2008, the smaller the jet diameter, 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, the large-diameter jet port will cause the flow rate to decrease, and the diffusion effect of the fluid after leaving the jet port will also be weakened, by replacing the flow limiting port 2008 of different sizes to limit the diameter of the rotary jet pile, the diameter of the rotary jet pile is changed, and the adjustment is made in advance before use, when the required flow limiting port 2008 is reached, the telescopic end of the second electric telescopic rod 2000 will drive the clamping block 1009 to slide downward and be clamped with the limiting groove II 2007 at the top of the sliding adjusting block 2006, under the limiting action of the limiting ring 1006, the sliding adjusting block 2006 and the threaded sleeve block 2003 become an integral whole and rotate together, and the flow limiting port 2008 is fixed, the present application improves the accuracy and flexibility of the diameter adjustment of the rotary jet pile, and significantly enhances the construction efficiency and quality, provides strong technical support for the rotary jet pile construction under complex geological conditions, and the rotary jet grouting pipe 1000 can change direction conveniently, this feature makes the device have operation flexibility, during the construction process, the operator can adjust the rotation direction of the rotary jet grouting pipe 1000 according to the actual needs, to ensure that the slurry can be accurately sprayed to the predetermined position, and this ability to change direction makes the replacement of the flow limiting port 2008 extremely simple, the operator can randomly select and fix the flow limiting port 2008 of different diameters without complex operation steps, to adapt to different construction requirements and geological conditions, this design not only greatly improves the construction efficiency and reduces the operation difficulty, but also ensures the accurate control of the diameter of the rotary jet pile, and provides a solid guarantee for the engineering quality;

[0056] In addition, the present application takes a 30m deep rotary jet pile curtain as an example, according to the general design idea and method, if the rotary jet pile diameter is 1000mm, the design overlap width is 350mm, and the pile spacing is 650mm, a large number of water leakage areas will exist at the bottom of the curtain. If the design width is increased to overcome this problem, method two, 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 overlapping method of the present application, the same depth of 30m and the pile spacing of 650mm, 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, and the design overlap width of the lower section 20m-30m is 650mm, then the diameter of the pile in this section is 1300mm. For the same 22750mm long water stop curtain, the volume of the rotary jet pile used by the three methods is calculated as 825m 3 , 1531m 3 and 1020m 3 The overlapping method of the present application is 195m 3 more than the pile of method one, i.e. 23.6%; the overlapping method of the present application is 511m 3 less than method two, i.e. 50%. The overlapping method of the present application uses 23.6% more engineering quantity than method one, but can avoid the problem of not overlapping at the bottom and greatly improve the water stopping effect of the water stop curtain. The overlapping method of the present application and method two can both avoid the problem of not overlapping at the bottom, but the overlapping method of the present application saves 50% of the engineering quantity compared to method two. Therefore, the overlapping method of the present application is the best method that combines quality and cost, which slightly increases the cost while greatly improving the water stopping effect.

[0057] Although embodiments of the present application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the application, the scope of which 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 jet mechanism (1) comprises a rotary jet unit (10), and the surface of the rotary jet unit (10) is provided with an adjusting unit (20); The rotary jet unit (10) comprises a jet grouting pipe (1000), the surface of the jet grouting pipe (1000) is provided with a spray head (1001), the bottom end of the jet grouting pipe (1000) is fixedly connected with a drill bit (1002), the surface of the end of the drill bit (1002) away from the jet grouting pipe (1000) is fixedly connected with a down-the-hole hammer (1003), the surface of the jet grouting pipe (1000) is fixedly connected with a sliding frame (1004), the surface of the sliding frame (1004) is fixedly connected with an electric telescopic rod I (1005), and the surface of the sliding frame (1004) is fixedly connected with a limiting ring (1006); the telescopic end of the electric telescopic rod I (1005) is fixedly connected with a clamping block (1009), the surface of the clamping block (1009) is slidably connected with the limiting ring (1006), and the surface of the clamping block (1009) is clamped with the limiting groove II (2007); 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 with a limiting block (2002), the limiting block (2002) is fixedly connected with a sliding block (2001) penetrating through the sliding frame (1004) and the limiting block (2002), and the surface of the limiting block (2002) is slidably connected with the inner wall of the sliding frame (1004); The adjusting unit (20) is located on the surface of the jet grouting pipe (1000) and is used for adjusting the jet diameter of the jet grouting pipe (1000), the adjusting unit (20) comprises an electric telescopic rod II (2000), the telescopic end of the electric telescopic rod II (2000) is fixedly connected with a sliding block (2001), and the end of the sliding block (2001) away from the electric telescopic rod II (2000) is fixedly connected with a limiting block (2002); the adjusting unit (20) further comprises a threaded sleeve block (2003), the surface of the threaded sleeve block (2003) is provided with threads, the surface of the threaded sleeve block (2003) is provided with a liquid outlet (2004), the top end of the threaded sleeve block (2003) is provided with a limiting groove I (2005), the surface of the threaded sleeve block (2003) is threadedly connected with a sliding adjusting block (2006), the surface of the sliding adjusting block (2006) is provided with flow limiting openings (2008) with different diameters, the top end of the sliding adjusting block (2006) is provided with a limiting groove II (2007), and the surface of the limiting block (2002) is clamped with the limiting groove I (2005).

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

3. The variable diameter jet grout pile according to claim 1, wherein: The flow limiting port (2008) is provided with four groups, and the four groups of flow limiting ports (2008) are distributed in a circumferential array around the surface of the sliding adjustment block (2006). The limiting groove two (2007) is provided with four, and the four limiting grooves two (2007) are distributed in a circumferential array around the top end of the sliding adjustment block (2006).

4. A method for overlapping variable-diameter jet grouting piles, based on the variable-diameter jet grouting pile of claim 1, characterized in that: The method comprises the following steps: S1: Determine the overlap length: The overlap length should be determined according to the geological conditions, pile diameter changes and design requirements; S2: Adjust the grouting parameters: In the overlap area, the grouting parameters, such as grouting pressure and grouting volume, need to be adjusted appropriately to ensure that the slurry can fully fill the gap between the pile bodies. By increasing the grouting pressure or grouting volume, the permeability and consolidation effect of the slurry can be improved; S3: Control the lifting speed of rotary jet grouting: In the overlap area, slow down the lifting speed of rotary jet grouting to ensure that the slurry and soil are fully mixed and stirred; S4: Adjust the rotary jet grouting diameter: During the overlap process, the position of the sliding adjustment block (2006) is adjusted to replace the flow limiting port of different sizes, thereby realizing the variable diameter of the pile hole. The design of the adjustment unit (20) allows the diameter of the pile hole to be adjusted according to the variable diameter overlap method of decreasing from top to bottom during overlap; S5: Quality detection and monitoring: After the overlap is completed, quality detection and monitoring should be carried out to ensure that the overlap quality meets the design requirements. Drilling core and water injection test methods are used for detection to ensure that the connection between the pile bodies is tight and effective.

5. The method according to claim 4, wherein: In S3, control the lifting speed of rotary jet grouting: In the overlap area, the mixing and stirring of the slurry and soil must be sufficient to ensure effective connection between adjacent pile bodies. Therefore, the lifting speed of rotary jet grouting should not be too fast, otherwise the slurry cannot fully penetrate into the soil, resulting in poor consolidation effect. On the contrary, slowing down the lifting speed of rotary jet grouting can give the slurry enough time to mix with the soil, thereby improving the bearing capacity and stability of the pile body.

6. The method according to claim 4, wherein: In S4, adjust the rotary jet grouting diameter: During the rotary jet grouting process, the rotary jet grouting is divided into three layers, and the rotary jet grouting curtain is 30m deep. When the pile spacing is 650mm, the design overlap width of the upper section 10m is 250mm, the pile body diameter of this section is 900mm, the design overlap width of the middle section 10m-20m is 450mm, the pile body diameter of this section is 1100mm, and the design overlap width of the lower section 20m-30m is 650mm. The diameter of the pile body in this section is 1300mm.

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