Rectangular curve pipe jacking thixotropic mud drag reduction characteristics test system and resistance calculation method

Abstract

The present invention provides a test system for the drag reduction characteristics of rectangular curved pipe jacking thixotropic mud and a method for calculating resistance, including a model box, a grouting assembly, a slider, a sliding control assembly, a horizontal load pressurization assembly, a data acquisition assembly, a data acquisition instrument and a computer, wherein a soil body is contained in the model box, a sliding track is arranged in the soil body, and the slider can move on the sliding track; the grouting assembly can grout into the soil body; the sliding control assembly can control the movement of the slider; the horizontal load pressurization assembly can provide lateral pressure to the slider through the soil body; the data acquisition assembly is used to collect test data, the data acquisition assembly is connected to the data acquisition instrument, and the data acquisition instrument is connected to the computer. The test system can test the mud drag reduction effect of the curved pipe jacking, and the rectangular pipe jacking soil friction resistance calculation formula established according to the test results provides a reliable basis for the subsequent actual construction process of the curved pipe jacking.

Description

Technical Field

[0001] The invention relates to the field of pipe jacking engineering, and in particular to a test system for the drag reduction characteristics of thixotropic mud for rectangular curve pipe jacking and a resistance calculation method. Background Art

[0002] The pipe jacking method is a dark excavation construction technology that constructs large underground spaces in a trenchless manner. Compared with underground space construction methods such as open excavation and shield tunneling, it has significant advantages such as low comprehensive cost, less traffic interference, and less environmental impact. It plays an irreplaceable role in the field of municipal engineering that crosses water bodies on traffic arteries and densely populated areas of ground and underground structures. The frictional resistance generated by the surrounding soil during the jacking process will increase with the increase of the jacking distance. Excessive jacking force will inevitably increase the bearing capacity of the pipe and the working well, increase investment and technical measures, and may even cause engineering accidents due to excessive jacking force. Therefore, how to overcome and minimize the huge jacking force in pipe jacking construction has become the key to pipe jacking construction.

[0003] In order to reduce the friction resistance between the pipeline and the soil, it is usually necessary to inject thixotropic mud into the outer wall of the pipeline. Thixotropic mud is a drag-reducing material made of bentonite, water and chemical treatment agents. During the pipe jacking construction process, it fills the 2-5 cm annular space between the pipe jacking and the soil. On the one hand, it can convert the dry friction between the pipe jacking and the soil into liquid friction, thereby reducing the friction resistance of the jacking; on the other hand, it can fill the gap between the pipe jacking and the soil, thereby reducing the deformation of the soil and supporting the stratum. Thixotropic mud does not flocculate or segregate when it is left still for a long time, and has sufficient fluidity when disturbed, that is, thixotropy. Thixotropy is the basic factor for the mud to play a role in the process of pipe jacking. At the contact point with the soil, the mud penetrates into the soil by its own weight. At this time, the thixotropic mud loses part of its water and becomes thicker, and the static shear strength increases, forming a thin, tough, impermeable layer of solid particle cement, that is, mud skin. The mud skin can effectively maintain the stability of the soil. It greatly improves the efficiency of pipe jacking construction and reduces the probability of accidents.

[0004] Since the pipe jacking method is a new type of trenchless pipeline laying technology for underground projects, there are still many deficiencies in the research on the friction resistance test of special pipelines, especially the deficiencies in the research on the friction resistance test of thixotropic mud for rectangular curved pipe jacking. At present, most of the research on the drag reduction effect of mud is determined by linear jacking sliding test, which makes it difficult to accurately obtain the drag reduction effect of the drag reduction mud for rectangular curved pipe jacking.

[0005] Therefore, in order to determine the drag reduction performance of thixotropic mud for curved pipe jacking, a test system for the drag reduction characteristics of thixotropic mud for rectangular curved pipe jacking and a drag calculation method are urgently needed. Summary of the invention

[0006] The purpose of the present invention is to provide a rectangular curve jacking pipe thixotropic mud drag reduction property testing system and a resistance calculation method. The testing system can test the mud drag reduction effect of the curve jacking pipe, and establish a rectangular jacking pipe-soil friction resistance calculation formula based on the test results, providing a reliable basis for the subsequent actual construction process of the curve jacking pipe.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] A rectangular curve jacking pipe thixotropic mud drag reduction property test system comprises a model box, a grouting assembly, a slider, a sliding control assembly, a horizontal load pressurization assembly, a data acquisition assembly, a data acquisition instrument and a computer, wherein the model box contains soil, a sliding track is provided in the soil, and the slider can move on the sliding track; the grouting assembly can grout into the soil; the sliding control assembly can control the movement of the slider; the horizontal load pressurization assembly can provide lateral pressure to the slider through the soil; the data acquisition assembly is used to collect test data, the data acquisition assembly is connected to the data acquisition instrument, and the data acquisition instrument is connected to the computer.

[0009] Furthermore, in the above-mentioned rectangular curve jacking pipe thixotropic mud drag reduction property test system, the model box includes an outer ring, an inner ring and a bottom plate, the outer ring is sleeved on the outside of the inner ring, the axis of the outer ring and the axis of the inner ring are both collinear with the axis of the model box, and the lower end of the outer ring and the lower end of the inner ring are both connected to the bottom plate; the soil body includes an inner soil body, a lower soil body and an outer soil body, and the inner soil body, the lower soil body and the outer soil body are all located between the outer ring and the inner ring; the outer side of the outer soil body is close to the outer ring, the inner side of the inner soil body is close to the inner ring, the outer side of the lower soil body is in contact with the inner side of the outer soil body, and the inner side of the lower soil body is in contact with the inner soil body. The outer side of the slider is in contact with the outer side, and the sliding track is formed between the upper side of the lower soil body, the inner side of the outer soil body and the outer side of the inner soil body; the horizontal cross-section of the slider is a fan ring, the center of the fan ring is located at the axis of the model box, and the central angle of the fan ring is 15°~30°. The slider slides in the sliding track to simulate the jacking effect of the actual curved jacking pipe. The upper surface of the slider is provided with a counterweight hole recessed into the interior of the slider, and the counterweight hole is a cylindrical structure. A counterweight block is provided in the counterweight hole. By changing the mass of the counterweight block, the overburden pressure during the actual curved jacking process can be simulated. The diameter of the counterweight hole is 40mm~60mm, and the depth of the counterweight hole is 8mm~10mm; the diameter of the inner ring is D 1, the diameter of the outer ring is D 2, D2=6 D 1~10 D 1; The height of the slider from the bottom plate is H 1, the height of the outer soil layer is H 3. H 3=2× H 1, the height of the inner soil layer is H 4. H 4=2× H 1, the height of the lower soil layer is H 5. H 5= H 1.

[0010] Furthermore, in the above-mentioned rectangular curve jacking pipe thixotropic mud drag reduction characteristics test system, the sliding control assembly includes a rotating shaft, a rotating arm, a fixed pulley and a fixed strap, the rotating shaft is arranged in the inner ring, the lower end of the rotating shaft is connected to the bottom plate, the upper end of the rotating shaft is connected to one end of the rotating arm, the other end of the rotating arm is connected to the fixed pulley, the axis of the rotating shaft is colinear with the axis of the model box, and the rotating shaft can provide torque to the rotating arm after starting; one end of the fixed strap is wrapped around the slider, and the other end of the fixed strap is wrapped around the fixed pulley, the rotating shaft drives the rotating arm to rotate, and then can provide traction to the slider through the fixed pulley. The traction force is directed in the tangent direction of the sliding track; the rotating arm comprises a first vertical section, a horizontal section and a second vertical section, the lower end of the first vertical section is connected to the upper end of the rotating shaft, the upper end of the first vertical section is connected to one end of the horizontal section, the upper end of the second vertical section is connected to the other end of the horizontal section, the lower end of the second vertical section is connected to the fixed pulley by bolts, the horizontal section is provided with a telescopic structure, the telescopic structure can extend or shorten the horizontal section and adjust the force arm of the rotating arm, thereby adjusting the curvature radius of the slider sliding along the model box and making the connection point of the fixing strap and the fixed pulley located on the extension line of the slider axis; the height of the slider is H 2. The distance between the axis of the fixed pulley and the bottom plate is H 6. H 6= H 1+1 / 2× H 2; The interior of the rotating shaft and the interior of the rotating arm are both provided with hollow channels for the data line to pass through.

[0011] Furthermore, in the above-mentioned rectangular curve jacking pipe thixotropic mud drag reduction characteristic test system, the rotating shaft is connected to the data acquisition instrument, and the computer can adjust the rotation speed of the rotating shaft. ω The data acquisition instrument can set the rotation speed of the rotating shaft ω Corresponding torque T Record the start and stop of the rotating shaft and change the rotation speed ω The movement of the slider can be made to conform to the movement law of the actual curved jacking pipe; the data acquisition component includes a pressure box and a tension meter, the pressure boxes are arranged on both sides and the bottom of the slider in contact with the soil, the pressure box is used to monitor the pressure changes on the two sides and the bottom of the slider, the data line of the pressure box passes through the rotating shaft and the hollow channel in the rotating arm in turn to be connected to the data acquisition instrument, the data acquisition instrument collects the pressure data on both sides and the bottom of the slider through the pressure box, the data acquisition instrument transmits the collected side pressure data to the computer, the computer calculates according to the pressure data collected by the pressure box to obtain the real-time values ​​of the side pressure and the bottom pressure of the slider during the sliding process; the tension meter is arranged on the contact end of the fixing strap and the slider, the tension meter is connected to the data acquisition instrument, and the tension meter is used to record the tension generated by the sliding control component on the slider when it is working.

[0012] Furthermore, in the above-mentioned rectangular curve jacking pipe thixotropic mud drag reduction property test system, the horizontal load pressurization component includes an inner water belt, an outer water belt, a water storage tank and a water injection pump, the outer water belt is laid in a circle close to the inner side wall of the outer circular ring, and the inner water belt is laid in a circle close to the outer side wall of the inner circular ring; the inner water belt is connected to one end of the first water injection pipe through a first movable joint, the other end of the first water injection pipe is connected to the water storage tank, the outer water belt is connected to one end of the second water injection pipe through a second movable joint, the other end of the second water injection pipe is connected to the water storage tank, and the water injection pump is connected to the water storage tank through a third water injection pipe; a first switch valve is provided on the first water injection pipe, and a second switch valve is provided on the second water injection pipe, the first switch valve is used to control the liquid flow between the inner water belt and the water storage tank, and the second switch valve can be used to control the liquid flow between the outer water belt and the water storage tank, and the inner layer of soil can be made to flow by injecting liquid into the inner water belt and the outer water belt. and the outer soil are in contact with the two side surfaces of the slider respectively, and the slider is subjected to pressure from the inner soil and the outer soil, which can simulate the lateral pressure of the soil on the actual rectangular curve jacking pipe during the jacking process; the bottom of the inner water belt and the bottom of the outer water belt are both provided with liquid outlets, and the liquid in the inner water belt or the outer water belt can be fully drained by using the liquid outlets; the first switch valve and the second switch valve are both digital liquid flow meters, and the first switch valve and the second switch valve are both connected to the computer, and the computer can control the flow of the liquid flowing into the inner water belt and the outer water belt, thereby changing the lateral pressure provided by the inner water belt and the outer water belt to the slider; the data acquisition component also includes a pressure membrane, and the inner side of the outer water belt and the outer side of the inner water belt are both attached with the pressure membrane, and the pressure membrane is connected to the data acquisition instrument through a data line, and the pressure membrane is a flexible thin film pressure-sensitive sensor, and the computer monitors the change of the lateral pressure in real time through the pressure membrane.

[0013] Furthermore, in the above-mentioned rectangular curve jacking pipe thixotropic mud drag reduction characteristics test system, the grouting assembly includes a grouting pump and a grouting pipe, the two side surfaces and the bottom surface of the slider in contact with the soil are provided with grouting holes, one end of the grouting pipe is connected to the grouting pump, the grouting pipe is fixed to the slider after passing through the rotating shaft and the hollow channel in the rotating arm in turn, the other end of the grouting pipe passes through the slider and is connected to the grouting hole, the grouting pump injects thixotropic mud into the soil through the grouting hole, thereby improving the friction resistance of the slider during sliding, simulating the slurry drag reduction effect during the actual curved jacking process on site.

[0014] On the other hand, a resistance calculation method is provided, which is implemented using the above-mentioned rectangular curve jacking pipe thixotropic mud drag reduction characteristic test system, and includes the following steps:

[0015] S1 Preparation of sliders: Prepare sliders according to the actual requirements of rectangular curve segments;

[0016] S2 installs the horizontal load pressurizing assembly: place the inner water belt in contact with the inner ring of the model box, and place the outer water belt in contact with the outer ring of the model box;

[0017] S3 soil laying: Take soil samples from the rectangular curve jacking layer at the construction site and lay them evenly in the test box in layers. During the laying of soil samples, a sliding track is reserved and the slider is placed on the sliding track. Counterweights of different masses are placed in the counterweight holes on the upper surface of the slider to simulate the actual soil pressure.

[0018] S4 Install the sliding control assembly: place the rotating shaft at the center of the model box, adjust the rotating arm so that the fixed pulley is located at the extension line of the slider axis, and connect the fixed pulley and the slider with a fixing strap;

[0019] S5 installs the grouting assembly and the data acquisition instrument: connect the grouting pipe and the data line to the slider through the hollow channel of the rotating arm, pass the grouting pipe through the slider and place it in the grouting hole, connect the data line to the pressure membranes on both sides and the bottom of the slider, and connect the data line to the data acquisition instrument;

[0020] S6 single-sided friction test: When performing a single-sided friction test, the two sides of the slider do not contact the soil, and only the bottom friction test of the slider is performed. The slider is subjected to horizontal tension through the sliding control component, so that the slider slides to the set position at a uniform speed;

[0021] S7 Three-sided friction test: Open the water injection pump and the first and second switch valves, inject liquid into the inner and outer water hoses, make both sides of the slider contact the soil, and conduct three-sided friction test on the two sides and bottom of the slider. Apply horizontal pulling force to the slider through the sliding control component to make the slider slide to the set position at a uniform speed;

[0022] S8 Analysis and evaluation of thixotropic mud drag reduction performance: Based on the test results, a calculation formula for the friction between pipe and soil or pipe and slurry is established, and the thixotropic mud drag reduction effect is analyzed and evaluated by comparing the changes in the friction coefficient of the slider.

[0023] Furthermore, in the above resistance calculation method, in step S8, the friction force between pipe and soil or between pipe and slurry is F , F The rotation speed of the slider sliding uniformly with the rotation axis ω Corresponding torque T Satisfies the following relationship:

[0024] Formula (1)

[0025] In formula (1), l is the torque of the rotating arm;

[0026] The pipe-soil friction Normal pressure between pipe and soil interface σ , contact area between slider and soil S Lubrication conditions between pipe and soil μ The specific expression is as follows:

[0027] Formula (2)

[0028] In formula (2), S s1 is the area of ​​the inner surface of the slider in contact with the soil, S s2 is the area of ​​the outer surface of the slider in contact with the soil, S b is the area of ​​the bottom surface of the slider, σ s is the normal pressure on the side surface between pipe and soil, σ b is the normal pressure at the bottom between the pipe and soil action surface;

[0029] A counterweight is arranged above the slider to simulate the pressure of the soil layer overlying the jacking pipe, and the lateral pressure exerted by the horizontal load pressurizing assembly on the soil F k Used to simulate the lateral normal pressure between the pipe and soil interaction surface σ s The friction between the pipe and the pulp Mud shear stress between pipe and slurry τ The contact area between the slider and the soil S The influence of the mud shear stress between the pipe and the slurry τ It is quantitatively characterized by the flat plate fluid model and the Herschel-Bulkley rheological model. The specific expression is as follows:

[0030] Formula (3)

[0031] In formula (3), S b is the area of ​​the bottom surface of the slider, K is the consistency coefficient; n is the rheological index; V is the jacking speed, d is the mud thickness, where the dynamic shear stress τ 0, consistency coefficient K , rheological coefficient n All are measured by a six-speed viscometer.

[0032] Further, in the above-mentioned resistance calculation method, in the step S6, a single-side friction resistance test is first performed without grouting, and then a thixotropic slurry is injected into the soil at the bottom of the slider using a grouting assembly, and a single-side friction resistance test is performed, and the drag reduction effect of the thixotropic slurry is analyzed and evaluated by comparing the change in the friction coefficient of the slider; the ratio of the friction resistance of the slider bottom surface without grouting to the friction resistance with grouting is k 1 , through k 1 The drag reduction effect of thixotropic mud is evaluated by numerical analysis. The specific expression is as follows:

[0033] Formula (4)

[0034] In formula (4), g is the acceleration due to gravity, M is the mass of the slider, m is the mass of the counterweight.

[0035] Furthermore, in the above-mentioned resistance calculation method, in the step S7, firstly, a three-sided friction resistance test is performed without grouting, and then a thixotropic slurry is injected into the soil on both sides and the bottom of the slider using a grouting assembly, and a three-sided friction resistance test is performed, and the drag reduction effect of the thixotropic slurry is analyzed and evaluated by comparing the change in the friction coefficient of the slider;

[0036] The ratio of the three-sided friction resistance of the slider without grouting to the grouting friction resistance is k 2 , through k 2 The drag reduction effect of thixotropic mud is evaluated by numerical analysis. The specific expression is as follows:

[0037] Formula (5)

[0038] In formula (5), g is the acceleration due to gravity, M is the mass of the slider, m is the mass of the counterweight.

[0039] It can be seen from the analysis that the present invention discloses a test system for the drag reduction characteristics of thixotropic mud for rectangular curved jacking pipes and a method for calculating resistance. The test system simulates the jacking process of rectangular curved jacking pipes by setting a model box, a grouting assembly and a sliding control assembly, and by sliding a slider on a sliding track. The overburden pressure in the actual jacking process of curved jacking pipes is simulated by configuring counterweights of different masses, and the side pressure of the slider is changed by a horizontal load pressurizing assembly to simulate different soil pressures in the actual jacking process of curved jacking pipes. By changing the grouting pressure and the slurry ratio, the grouting pressure and the ratio of bentonite mud with the best drag reduction effect under different soil pressure environments are accurately obtained, and then the friction force variation law of the pipe sections of rectangular curved jacking pipes under different pressures and lubrication conditions is explored. Moreover, by simulating the jacking process of rectangular curved jacking pipes, a universal calculation formula for the friction resistance of rectangular curved jacking pipes is provided, which provides a reliable basis for the subsequent actual construction process of curved jacking pipes. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. Among them:

[0041] Figure 1 It is a schematic cross-sectional structure diagram of an embodiment of the present invention.

[0042] Figure 2 It is a schematic diagram of the three-dimensional structure of an embodiment of the present invention.

[0043] Figure 3 It is a schematic diagram of the three-dimensional structure of the assembly of the sliding control assembly and the model box according to an embodiment of the present invention.

[0044] Figure 4 for Figure 2 Schematic diagram of the top view structure.

[0045] Figure 5 It is a structural schematic diagram of a horizontal load pressurizing assembly according to an embodiment of the present invention.

[0046] Figure 6 It is a schematic structural diagram of the cooperation between a fixed pulley and a sliding block according to an embodiment of the present invention.

[0047] Figure 7 FIG. 4 is a flow chart of a resistance calculation method according to an embodiment of the present invention.

[0048] Explanation of the reference numerals: 1 outer ring; 2 inner ring; 3 bottom plate; 4 inner soil layer; 5 lower soil layer; 6 outer soil layer; 7 sliding track; 8 slider; 9 counterweight; 10 rotating shaft; 11 rotating arm; 12 first vertical section; 13 horizontal section; 14 second vertical section; 15 telescopic structure; 16 fixed pulley; 17 fixed strap; 18 inner water hose; 19 outer water hose; 20 water storage tank; 21 water injection pump; 22 first movable joint; 23 first water injection pipe; 24 second movable joint; 25 second water injection pipe; 26 third water injection pipe; 27 first switch valve; 28 second switch valve; 29 grouting pump; 30 grouting pipe; 31 data acquisition instrument; 32 computer; 33 grouting hole. DETAILED DESCRIPTION

[0049] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments. Each example is provided by way of explanation of the present invention and does not limit the present invention. In fact, it will be clear to those skilled in the art that modifications and variations may be made in the present invention without departing from the scope or spirit of the present invention. For example, a feature shown or described as a part of one embodiment may be used in another embodiment to produce yet another embodiment. Therefore, it is desired that the present invention encompasses such modifications and variations within the scope of the appended claims and their equivalents.

[0050] In the description of the present invention, the terms "longitudinal", "lateral", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and do not require that the present invention must be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention. The terms "connected", "connected" and "set" used in the present invention should be understood in a broad sense. For example, it can be a fixed connection or a detachable connection; it can be a direct connection or an indirect connection through an intermediate component; it can be a wired electrical connection, a radio connection, or a wireless communication signal connection. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0051] One or more examples of the present invention are shown in the accompanying drawings. The detailed description uses numbers and letter labels to refer to features in the drawings. Like or similar labels in the drawings and description have been used to refer to like or similar parts of the present invention. As used herein, the terms "first", "second", "third", etc. are used interchangeably to distinguish one component from another and are not intended to indicate the location or importance of individual components.

[0052] like Figures 1 to 7 As shown, according to an embodiment of the present invention, a rectangular curve jacking pipe thixotropic mud drag reduction property testing system is provided, such as Figure 1 As shown, it includes a model box, a grouting component, a slider 8, a sliding control component, a horizontal load pressurization component, a data acquisition component, a data acquisition instrument 31 and a computer 32, wherein the model box contains soil, a sliding track 7 is provided in the soil, and the slider 8 can move on the sliding track 7; the grouting component can grout into the soil, and the dry friction between the slider 8 and the soil can be converted into liquid friction by grouting into the soil by the grouting component, thereby reducing the friction resistance of the slider 8; the sliding control component can control the movement of the slider 8; the horizontal load pressurization component can provide lateral pressure to the slider 8 through the soil; the data acquisition component is used to collect test data, the data acquisition component is connected to the data acquisition instrument 31, and the data acquisition instrument 31 is connected to the computer 32.

[0053] Furthermore, if Figure 3 As shown, the model box is a double-circular cavity structure with an open upper end. The model box includes an outer ring 1, an inner ring 2 and a bottom plate 3. The outer ring 1 is sleeved on the outer side of the inner ring 2. The axes of the outer ring 1 and the inner ring 2 are both in line with the axis of the model box. The lower ends of the outer ring 1 and the inner ring 2 are both connected to the bottom plate 3. The soil includes an inner soil 4, a lower soil 5 and an outer soil 6. The inner soil 4, the lower soil 5 and the outer soil 6 are all located between the outer ring 1 and the inner ring 2. The outer side of the outer soil 6 is close to the outer ring 1, the inner side of the inner soil 4 is close to the inner ring, the outer side of the lower soil 5 is in contact with the inner side of the outer soil 6, and the inner side of the lower soil 5 is in contact with the outer side of the inner soil 4. A sliding track 7 is formed between the upper side of the lower soil 5, the inner side of the outer soil 6 and the outer side of the inner soil 4. The height of the soil (inner soil 4, lower soil 5 and outer soil 6) can be adjusted according to the actual engineering situation. The slider 8 is located above the lower soil 5. The horizontal section of the slider 8 is a fan ring. The center of the fan ring is located at the axis of the model box. The central angle of the fan ring is 15°~30°. The slider 8 slides in the sliding track 7 to simulate the jacking effect of the actual curved jacking pipe. The upper surface of the slider 8 is provided with a counterweight hole recessed into the inside of the slider 8. The counterweight hole is a cylindrical structure, such as Figure 6 As shown, a counterweight block 9 is arranged in the counterweight hole, and counterweight blocks 9 of various masses can be placed in the counterweight hole. By changing the mass of the counterweight block 9, the overburden pressure in the actual curve jacking process can be simulated. The diameter of the counterweight hole is 40mm~60mm, and the depth of the counterweight hole is 8mm~10mm; the diameter of the inner ring 2 is D 1. The diameter of the outer ring is D 2, D 2=6 D 1~10 D 1; Preferably, the height of the slider 8 from the bottom plate 3 is H 1, the height of the outer soil layer 6 is H 3. H 3=2×H 1, the height of the inner soil 4 is H 4. H 4=2× H 1, the height of the lower soil layer 5 is H 5. H 5= H 1.

[0054] Furthermore, if Figure 2 As shown, the sliding control assembly includes a rotating shaft 10, a rotating arm 11, a fixed pulley 16 and a fixed strap 17. The rotating shaft 10 is arranged in the inner ring 2. The lower end of the rotating shaft 10 is connected to the bottom plate 3. The upper end of the rotating shaft 10 is threadedly connected to one end of the rotating arm 11. The other end of the rotating arm 11 is threadedly connected to the fixed pulley 16. The axis of the rotating shaft 10 is colinear with the axis of the model box. After the rotating shaft 10 is started, it can provide torque for the rotating arm 11; one end of the fixed strap 17 is wrapped around the slider 8, and the other end of the fixed strap 17 is wrapped around the fixed pulley 16. The rotating arm 11 is tied and connected to the slider 8 through the fixed strap 17. The rotating shaft 10 drives the rotating arm 11 to rotate, and then can provide traction for the slider 8 through the fixed pulley 16. The direction of the traction force is the tangent direction of the sliding track 7; the rotating arm 11 includes a first vertical section 12, a horizontal section 13 and a second vertical section 14, the lower end of the first vertical section 12 is connected to the upper end of the rotating shaft 10, the upper end of the first vertical section 12 is connected to one end of the horizontal section 13, the upper end of the second vertical section 14 is connected to the other end of the horizontal section 13, and the lower end of the second vertical section 14 is connected to the fixed pulley 16 by bolts, and the horizontal section 13 is provided with a telescopic structure 15, and the telescopic structure 15 can extend or shorten the horizontal section 13. By adjusting the telescopic length of the horizontal section 13, the force arm of the rotating arm 11 is adjusted, and then the curvature radius of the slider 8 sliding along the model box is adjusted, and the connection point of the fixing strap 17 and the fixed pulley 16 is located on the extension line of the axis of the slider 8; the height of the slider 8 is H 2. The distance between the axis of the fixed pulley 16 and the bottom plate 3 is H 6. H 6= H 1+1 / 2× H 2; The interior of the rotating shaft 10 and the interior of the rotating arm 11 are both provided with hollow channels for the data line to pass through.

[0055] Furthermore, the rotating shaft 10 is connected to the data acquisition device 31, and the computer 32 can adjust the rotation speed of the rotating shaft 10. ω The data acquisition device 31 can set the rotation speed of the rotating shaft 10 ω Corresponding torque T Recording, starting and stopping of the rotating shaft 10 and changing the rotation speed ω, which can make the movement of the slider 8 conform to the actual movement law of the curved jacking pipe; the data acquisition component includes a pressure box and a dynamometer. The two side surfaces and the bottom surface of the slider 8 in contact with the soil are both provided with pressure boxes. The pressure box is used to monitor the pressure changes on the two side surfaces and the bottom surface of the slider 8. The data line of the pressure box passes through the hollow channels in the rotating shaft 10 and the rotating arm 11 in turn to connect to the data acquisition instrument 31. The data acquisition instrument 31 collects the pressure data on both sides and the bottom pressure data of the slider 8 through the pressure box. The data acquisition instrument 31 transmits the collected side pressure data to the computer 32. The computer 32 calculates according to the pressure data collected by the pressure box to obtain the real-time values ​​of the side pressure and the bottom pressure of the slider 8 during the sliding process; a dynamometer is provided at the contact end of the fixed strap 17 and the slider 8, and the dynamometer is connected to the data acquisition instrument 31. The dynamometer is used to record the tension generated on the slider 8 when the sliding control component is working.

[0056] Furthermore, if Figure 4 As shown, it also includes a horizontal load pressurization component, which includes an inner water belt 18, an outer water belt 19, a water storage tank 20 and a water injection pump 21. The outer water belt 19 is laid in a circle close to the inner wall of the outer ring 1, and the inner water belt 18 is laid in a circle close to the outer wall of the inner ring 2. The outer water belt 19, soil and inner water belt 18 are laid and installed in the model box from the outside to the inside; Figure 5As shown, the inner water belt 18 is threadedly connected to one end of the first water injection pipe 23 through the first movable joint 22, and the other end of the first water injection pipe 23 is threadedly connected to the water storage tank 20, the outer water belt 19 is threadedly connected to one end of the second water injection pipe 25 through the second movable joint 24, and the other end of the second water injection pipe 25 is threadedly connected to the water storage tank 20, and the water injection pump 21 is connected to the water storage tank 20 through the third water injection pipe 26. Such an arrangement can facilitate the assembly and disassembly of the horizontal load pressurization component; a first switch valve 27 is provided on the first water injection pipe 23, and a second switch valve 28 is provided on the second water injection pipe 25. The first switch valve 27 is used to control the liquid flow between the inner water belt 18 and the water storage tank 20, and the second switch valve 28 can be used to control the liquid flow between the outer water belt 19 and the water storage tank 20. By injecting liquid into the inner water belt 18 and the outer water belt 19, the inner soil 4 and the outer soil 6 can be respectively contacted with the two sides of the slider 8, and the slider 8 is subjected to the pressure from the inner soil 4 and the outer soil 6. The pressure of the soil 6 can simulate the lateral pressure of the soil that the actual rectangular curve jacking pipe is subjected to during the jacking process; the bottom of the inner water belt 18 and the bottom of the outer water belt 19 are both provided with liquid outlets, and the liquid in the inner water belt 18 or the outer water belt 19 can be fully discharged by using the liquid outlets; the first switch valve 27 and the second switch valve 28 are both digital liquid flow meters, and the first switch valve 27 and the second switch valve 28 are both connected to the computer 32, and the computer 32 can control the flow rate of the liquid flowing into the inner water belt 18 through the first switch valve 27, and the computer 32 can control the flow rate of the liquid flowing into the outer water belt 19 through the second switch valve 28, thereby changing the lateral pressure provided by the inner water belt 18 and the outer water belt 19 to the slider 8; the data acquisition component also includes a pressure membrane, and a plurality of pressure membranes are attached to the inner side of the outer water belt 19 and the outer side of the inner water belt 18, and the pressure membrane is connected to the data acquisition instrument 31 through a data line, and the pressure membrane is a flexible thin film pressure-sensitive sensor, and the computer 32 monitors the change of the lateral pressure of the slider 8 in real time through the pressure membrane.

[0057] Furthermore, the grouting assembly includes a grouting pump 29 and a grouting pipe 30. The two side surfaces and the bottom surface of the slider 8 in contact with the soil are both provided with a plurality of grouting holes 33. One end of the grouting pipe 30 is connected to the grouting pump 29. The grouting pipe 30 is fixed to the slider 8 after passing through the hollow passages in the rotating shaft 10 and the rotating arm 11 in turn. The other end of the grouting pipe 30 passes through the slider 8 and is connected to the grouting hole 33. The grouting pump 29 injects thixotropic mud into the soil through the grouting hole 33, thereby improving the friction resistance during the sliding process of the slider 8, and simulating the drag reduction effect of the slurry during the actual on-site curved jacking process. By changing the grouting pressure of the grouting pump 29 and the ratio of the slurry, the grouting pressure and the ratio of the bentonite mud with the best drag reduction effect under different soil pressure environments can be accurately obtained, and the friction force variation law of the pipe section of the rectangular curved jacking pipe under different pressure and lubrication conditions can be explored.

[0058] The present invention also discloses a resistance calculation method, which is implemented by using the above-mentioned rectangular curve jacking pipe thixotropic mud drag reduction characteristic testing system, such as Figure 7 As shown, the following steps are included:

[0059] S1: Prepare the slider 8 according to the actual requirements of the rectangular curve segment;

[0060] S2 installs the horizontal load pressurizing assembly: place the inner water belt 18 in contact with the inner ring 2 of the model box, place the outer water belt 19 in contact with the outer ring 1 of the model box, connect the inner water belt 18 to the water storage tank 20 through the first water injection pipe 23, connect the outer water belt 19 to the water storage tank 20 through the second water injection pipe 25, and keep the first switch valve 27 and the second switch valve 28 in the closed state.

[0061] S3 laying soil: Take soil samples from the rectangular curve jacking layer at the construction site, and lay the soil samples evenly in layers in the test box. In the process of laying the soil samples, reserve a sliding track 7, place the slider 8 on the U-shaped sliding track 7 composed of the soil, and place counterweight blocks 9 of different masses in the counterweight holes on the upper surface of the slider 8 to simulate the actual covering soil pressure.

[0062] S4 installs the sliding control assembly: place the rotating shaft 10 at the center of the model box, and connect the fixed end of the rotating shaft 10 to the base plate 3, adjust the rotating arm 11 so that the fixed pulley 16 is located at the extension line of the axis of the slider 8, and connect the fixed pulley 16 to the slider 8 through the fixing strap 17.

[0063] S5 installs the grouting assembly and the data acquisition instrument 31: connect the grouting pipe 30 and the data line to the slider 8 through the hollow channel of the rotating arm 11, connect the grouting pipe 30 to the water injection pump 21, pass the grouting pipe 30 through the slider 8 and place it in the grouting hole 33, connect the data line to the pressure membranes on both sides and the bottom of the slider 8, and respectively connect the rotating shaft 10, the pressure box, the dynamometer, the pressure membrane, the first switch valve 27 and the second switch valve 28 to the data acquisition instrument 31.

[0064] S6 Single-sided friction resistance test: When conducting a single-sided friction resistance test, the two side surfaces of the slider 8 do not contact the soil, and only the bottom surface friction resistance test of the slider 8 is performed, that is, the bottom surface of the slider 8 contacts the lower soil 5, and the two side surfaces of the slider 8 do not contact the inner soil 4 and the outer soil 6. A horizontal pulling force is applied to the slider 8 through the sliding control component, so that the slider 8 slides at a uniform speed to the set position, and the data acquisition component is used to collect test data during the sliding process of the slider 8.

[0065] S7 three-sided friction test: open the water injection pump 21 and the first switch valve 27 and the second switch valve 28, inject liquid into the inner water hose 18 and the outer water hose 19, so that both sides of the slider 8 are in contact with the soil, and then perform a three-sided friction test on the two sides and the bottom of the slider 8. Apply a horizontal pulling force to the slider 8 through the sliding control component to make the slider 8 slide to the set position at a uniform speed. Use the data acquisition component to collect test data during the sliding process of the slider 8.

[0066] S8 thixotropic mud drag reduction performance analysis and evaluation: Based on the test results, a calculation formula for the friction between pipe and soil or pipe and slurry is established, and the thixotropic mud drag reduction effect is analyzed and evaluated by comparing the changes in the friction coefficient of slider 8.

[0067] The friction between pipe and soil or pipe and slurry is F , F The rotation speed of the slider 8 is pulled by the rotation shaft 10 at a uniform speed. ω Corresponding torque T Satisfies the following relationship:

[0068] Formula (1)

[0069] In formula (1), l is the moment of the rotating arm 11;

[0070] Friction between pipe and soil Normal pressure between pipe and soil interface σ , the contact area between slider 8 and soil S Lubrication conditions between pipe and soil μ The specific expression is as follows:

[0071] Formula (2)

[0072] In formula (2), S s1 is the area of ​​the inner side of the slider 8 in contact with the soil, S s2 is the area of ​​the outer side of the slider 8 in contact with the soil, S b is the area of ​​the bottom surface of the slider 8, σ s is the normal pressure on the side surface between pipe and soil, σ b The normal pressure on the bottom surface between the pipe and soil action surface. A counterweight block 9 is set above the slider 8 to simulate the pressure of the soil layer on the top pipe. The lateral pressure exerted by the horizontal load pressure component on the soil F k Used to simulate the lateral normal pressure between the pipe and soil interaction surface σ s Friction between pipe and pulp Mud shear stress between pipe and slurry τ The contact area between the slider 8 and the soil SInfluence, mud shear stress between pipe and slurry τ It is quantitatively characterized by the flat plate fluid model and the Herschel-Bulkley rheological model. The specific expression is as follows:

[0073] Formula (3)

[0074] In formula (3), S b is the area of ​​the bottom surface of the slider 8, K is the consistency coefficient; n is the rheological index; V is the jacking speed, d is the mud thickness, where the dynamic shear stress τ 0, consistency coefficient K , rheological coefficient n All are measured by a six-speed viscometer.

[0075] Furthermore, in step S6, a single-sided friction resistance test is first performed without grouting, and then thixotropic mud is injected into the soil at the bottom of the slider 8 using the grouting assembly, and a single-sided friction resistance test is performed, and the drag reduction effect of the thixotropic mud is analyzed and evaluated by comparing the changes in the friction coefficient of the slider 8.

[0076] The ratio of the non-grouting frictional resistance to the grouting frictional resistance on the bottom of the slider 8 is k 1 , through k 1 The drag reduction effect of thixotropic mud is evaluated by numerical analysis. The specific expression is as follows:

[0077] Formula (4)

[0078] In formula (4), g is the acceleration due to gravity, M is the mass of slider 8, m It is the mass of counterweight 9.

[0079] Furthermore, in step S7, a three-sided friction resistance test is first performed without grouting, and then thixotropic mud is injected into the soil on both sides and the bottom of the slider 8 using the grouting assembly, and a three-sided friction resistance test is performed. The drag reduction effect of the thixotropic mud is analyzed and evaluated by comparing the changes in the friction coefficient of the slider 8.

[0080] The ratio of the three-sided friction resistance of the slider 8 without grouting to the grouting friction resistance is k 2 , through k 2 The drag reduction effect of thixotropic mud is evaluated by numerical analysis. The specific expression is as follows:

[0081] Formula (5)

[0082] In formula (5), g is the acceleration due to gravity, M is the mass of slider 8, m It is the mass of counterweight 9.

[0083] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0084] A test system for the drag reduction characteristics of thixotropic mud for rectangular curved jacking pipes and a method for calculating resistance. The test system simulates the jacking process of rectangular curved jacking pipes by setting a model box, a grouting assembly and a sliding control assembly, and by sliding a slider 8 on a sliding track 7. The overburden pressure in the actual jacking process of the curved jacking pipes is simulated by configuring counterweights 9 of different masses, and the side pressure of the slider 8 is changed by a horizontal load pressurizing assembly to simulate different soil pressures in the actual jacking process of the curved jacking pipes. By changing the grouting pressure and the slurry ratio, the grouting pressure and the ratio of bentonite mud with the best drag reduction effect under different soil pressure environments are accurately obtained, and then the friction force variation law of the pipe sections of the rectangular curved jacking pipes under different pressures and lubrication conditions is explored. Moreover, by simulating the jacking process of the rectangular curved jacking pipes, a universal calculation formula for the friction resistance of rectangular curved jacking pipes is provided, which provides a reliable basis for the subsequent actual construction process of the curved jacking pipes.

[0085] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A rectangular curve jacking pipe thixotropic mud drag reduction property test system, characterized in that: It includes a model box, a grouting component, a slider, a sliding control component, a horizontal load pressurizing component, a data acquisition component, a data acquisition instrument and a computer, wherein: The model box contains soil, and a sliding track is provided in the soil, and the slider can move on the sliding track; The model box comprises an outer ring, an inner ring and a bottom plate, wherein the outer ring is sleeved on the outer side of the inner ring, the axis of the outer ring and the axis of the inner ring are both colinear with the axis of the model box, and the lower end of the outer ring and the lower end of the inner ring are both connected to the bottom plate; The soil body comprises an inner soil body, a lower soil body and an outer soil body, and the inner soil body, the lower soil body and the outer soil body are all located between the outer circular ring and the inner circular ring; The outer side of the outer soil layer is close to the outer ring, the inner side of the inner soil layer is close to the inner ring, the outer side of the lower soil layer is in contact with the inner side of the outer soil layer, the inner side of the lower soil layer is in contact with the outer side of the inner soil layer, and the sliding track is formed between the upper side of the lower soil layer, the inner side of the outer soil layer and the outer side of the inner soil layer; The grouting assembly is capable of injecting grout into the soil body; The sliding control component can control the movement of the sliding block; The horizontal load pressurizing assembly can provide lateral pressure to the sliding block through the soil; The horizontal load pressurizing assembly includes an inner water hose, an outer water hose, a water storage tank and a water injection pump. The outer water hose is laid in a circle close to the inner side wall of the outer circular ring, and the inner water hose is laid in a circle close to the outer side wall of the inner circular ring. The inner water belt is connected to one end of the first water injection pipe through a first movable joint, the other end of the first water injection pipe is connected to the water storage tank, the outer water belt is connected to one end of the second water injection pipe through a second movable joint, the other end of the second water injection pipe is connected to the water storage tank, and the water injection pump is connected to the water storage tank through a third water injection pipe; The first water injection pipeline is provided with a first switch valve, and the second water injection pipeline is provided with a second switch valve. The first switch valve is used to control the flow of liquid between the inner water belt and the water storage tank, and the second switch valve can be used to control the flow of liquid between the outer water belt and the water storage tank. By injecting liquid into the inner water belt and the outer water belt, the inner soil layer and the outer soil layer can be respectively contacted with two side surfaces of the slider. The slider is subjected to pressure from the inner soil layer and the outer soil layer, which can simulate the lateral pressure of the soil body that the actual rectangular curve jacking pipe is subjected to during the jacking process. The data acquisition component is used to collect test data. The data acquisition component is connected to the data acquisition instrument, and the data acquisition instrument is connected to the computer.

2. The rectangular curve jacking pipe thixotropic mud drag reduction property testing system according to claim 1 is characterized in that: The horizontal cross-section of the slider is a fan ring, the center of the fan ring is located at the axis of the model box, the central angle of the fan ring is 15°~30°, the slider slides in the sliding track to simulate the jacking effect of the actual curved jacking pipe, the upper surface of the slider is provided with a counterweight hole recessed into the inside of the slider, the counterweight hole is a cylindrical structure, a counterweight block is provided in the counterweight hole, and the overburden pressure in the actual curved jacking process can be simulated by changing the mass of the counterweight block, the diameter of the counterweight hole is 40mm~60mm, and the depth of the counterweight hole is 8mm~10mm; The diameter of the inner ring is D 1, the diameter of the outer ring is D 2, D 2=6 D 1~10 D 1; The height of the slider from the bottom plate is H 1, the height of the outer soil layer is H 3. H 3=2× H 1, the height of the inner soil layer is H 4. H 4=2× H 1, the height of the lower soil layer is H 5. H 5= H 1.

3. The rectangular curve jacking pipe thixotropic mud drag reduction property testing system according to claim 1 is characterized in that: The sliding control assembly includes a rotating shaft, a rotating arm, a fixed pulley and a fixed strap, wherein the rotating shaft is arranged in the inner ring, the lower end of the rotating shaft is connected to the bottom plate, the upper end of the rotating shaft is connected to one end of the rotating arm, the other end of the rotating arm is connected to the fixed pulley, the axis of the rotating shaft is colinear with the axis of the model box, and the rotating shaft can provide torque to the rotating arm after starting; One end of the fixing strap is wound around the slider, and the other end of the fixing strap is wound around the fixed pulley. The rotating shaft drives the rotating arm to rotate, thereby providing traction force to the slider through the fixed pulley, and the direction of the traction force is the tangent direction of the sliding track. The rotating arm comprises a first vertical section, a horizontal section and a second vertical section, the lower end of the first vertical section is connected to the upper end of the rotating shaft, the upper end of the first vertical section is connected to one end of the horizontal section, the upper end of the second vertical section is connected to the other end of the horizontal section, the lower end of the second vertical section is connected to the fixed pulley by bolts, and the horizontal section is provided with a telescopic structure, which can extend or shorten the horizontal section and adjust the force arm of the rotating arm, thereby adjusting the curvature radius of the slider sliding along the model box and making the connection point between the fixing strap and the fixed pulley located on the extension line of the slider axis; The height of the slider is H 2. The distance between the axis of the fixed pulley and the bottom plate is H 6. H 6= H 1+1 / 2× H 2; The interior of the rotating shaft and the interior of the rotating arm are both provided with hollow channels for the data line to pass through.

4. The rectangular curve jacking pipe thixotropic mud drag reduction property testing system according to claim 3 is characterized in that: The rotating shaft is connected to the data acquisition instrument, and the computer can adjust the rotation speed of the rotating shaft. ω The data acquisition instrument can set the rotation speed of the rotating shaft ω Corresponding torque T Record the start and stop of the rotating shaft and change the rotation speed ω The movement of the slider can be made to conform to the movement law of the actual curved pipe jacking; The data acquisition component includes a pressure box and a tension meter. The pressure boxes are provided on both sides and the bottom of the slider in contact with the soil. The pressure boxes are used to monitor the pressure changes on the two sides and the bottom of the slider. The data line of the pressure box passes through the rotating shaft and the hollow channel in the rotating arm in sequence to be connected to the data acquisition instrument. The data acquisition instrument collects the pressure data on both sides and the bottom of the slider through the pressure box. The data acquisition instrument transmits the collected side pressure data to the computer. The computer can calculate the real-time values ​​of the side pressure and the bottom pressure of the slider during the sliding process according to the pressure data collected by the pressure box. The dynamometer is arranged at the contact end between the fixing strap and the slider, the dynamometer is connected to the data acquisition instrument, and is used to record the pulling force generated by the sliding control component on the slider when the sliding control component is working.

5. The rectangular curve jacking pipe thixotropic mud drag reduction property testing system according to claim 3 is characterized in that: The bottom of the inner water belt and the bottom of the outer water belt are both provided with a liquid outlet, and the liquid in the inner water belt or the outer water belt can be fully drained by using the liquid outlet; The first switch valve and the second switch valve are both digital liquid flow meters, and the first switch valve and the second switch valve are both connected to the computer, and the computer can control the flow of liquid flowing into the inner water belt and the outer water belt, thereby changing the lateral pressure provided by the inner water belt and the outer water belt to the slider; The data acquisition component also includes a pressure membrane, which is attached to the inner side of the outer water belt and the outer side of the inner water belt. The pressure membrane is connected to the data acquisition instrument through a data line. The pressure membrane is a flexible thin film pressure-sensitive sensor. The computer monitors the changes in side pressure in real time through the pressure membrane.

6. The rectangular curve jacking pipe thixotropic mud drag reduction property testing system according to claim 3 is characterized in that: The grouting assembly includes a grouting pump and a grouting pipe. Grouting holes are provided on the two side surfaces and the bottom surface of the slider in contact with the soil. One end of the grouting pipe is connected to the grouting pump. The grouting pipe is fixed to the slider after passing through the rotating shaft and the hollow channel in the rotating arm in sequence. The other end of the grouting pipe passes through the slider and is connected to the grouting hole. The grouting pump injects thixotropic mud into the soil through the grouting hole, thereby improving the friction resistance of the slider during sliding, simulating the slurry drag reduction effect during the actual curved pipe jacking process on site.

7. A method for calculating resistance, implemented by using the rectangular curve jacking pipe thixotropic mud drag reduction characteristic testing system according to any one of claims 3 to 6, characterized in that: The steps include: S1 Preparation of sliders: Prepare sliders according to the actual requirements of rectangular curve segments; S2 installs the horizontal load pressurizing assembly: place the inner water belt in contact with the inner ring of the model box, and place the outer water belt in contact with the outer ring of the model box; S3 soil laying: Take soil samples from the rectangular curve jacking layer at the construction site and lay them evenly in the test box in layers. During the laying of soil samples, a sliding track is reserved and the slider is placed on the sliding track. Counterweights of different masses are placed in the counterweight holes on the upper surface of the slider to simulate the actual soil pressure. S4 Install the sliding control assembly: place the rotating shaft at the center of the model box, adjust the rotating arm so that the fixed pulley is located at the extension line of the slider axis, and connect the fixed pulley and the slider with a fixing strap; S5 installs the grouting assembly and the data acquisition instrument: connect the grouting pipe and the data line to the slider through the hollow channel of the rotating arm, pass the grouting pipe through the slider and place it in the grouting hole, connect the data line to the pressure membranes on both sides and the bottom of the slider, and connect the data line to the data acquisition instrument; S6 single-sided friction test: When performing a single-sided friction test, the two sides of the slider do not contact the soil, and only the bottom friction test of the slider is performed. The slider is subjected to horizontal tension through the sliding control component, so that the slider slides to the set position at a uniform speed; S7 Three-sided friction test: Open the water injection pump and the first and second switch valves, inject liquid into the inner and outer water hoses, make both sides of the slider contact the soil, and conduct three-sided friction test on the two sides and bottom of the slider. Apply horizontal pulling force to the slider through the sliding control component to make the slider slide to the set position at a uniform speed; S8 Analysis and evaluation of thixotropic mud drag reduction performance: Based on the test results, a calculation formula for the friction between pipe and soil or pipe and slurry is established, and the thixotropic mud drag reduction effect is analyzed and evaluated by comparing the changes in the friction coefficient of the slider.

8. The resistance calculation method according to claim 7, characterized in that: In step S8, the friction between pipe and soil or between pipe and slurry is F , F The rotation speed of the slider sliding uniformly with the rotation axis ω Corresponding torque T Satisfies the following relationship: Formula (1) In formula (1), l is the torque of the rotating arm; Friction between pipe and soil Normal pressure between pipe and soil interface σ , contact area between slider and soil S Lubrication conditions between pipe and soil μ The specific expression is as follows: Formula (2) In formula (2), S s1 is the area of ​​the inner surface of the slider in contact with the soil, S s2 is the area of ​​the outer surface of the slider in contact with the soil, S b is the area of ​​the bottom surface of the slider, σ s is the normal pressure on the side surface between pipe and soil, σ b is the normal pressure at the bottom between the pipe and soil action surface; A counterweight is arranged above the slider to simulate the pressure of the soil layer overlying the jacking pipe, and the lateral pressure exerted by the horizontal load pressurizing assembly on the soil F k Used to simulate the lateral normal pressure between the pipe and soil interaction surface σ s ; Friction between pipe and pulp Mud shear stress between pipe and slurry τ The contact area between the slider and the soil S The influence of the mud shear stress between the pipe and the slurry τ It is quantitatively characterized by the flat plate fluid model and the Herschel-Bulkley rheological model. The specific expression is as follows: Formula (3) In formula (3), S b is the area of ​​the bottom surface of the slider, K is the consistency coefficient; n is the rheological index; V is the jacking speed, d is the mud thickness, where the dynamic shear stress τ 0, consistency coefficient K , rheological index n All are measured by a six-speed viscometer.

9. The resistance calculation method according to claim 8, characterized in that: In the step S6, firstly, a single-side friction resistance test is performed without grouting, and then a thixotropic slurry is injected into the soil at the bottom of the slider using a grouting assembly, and a single-side friction resistance test is performed, and the drag reduction effect of the thixotropic slurry is analyzed and evaluated by comparing the change in the friction coefficient of the slider; The ratio of the non-grouting frictional resistance to the grouting frictional resistance on the bottom of the slider is k 1 , through k 1 The drag reduction effect of thixotropic mud is evaluated by numerical analysis. The specific expression is as follows: Formula (4) In formula (4), g is the acceleration due to gravity, M is the mass of the slider, m is the mass of the counterweight.

10. The resistance calculation method according to claim 8, characterized in that: In step S7, firstly, a three-sided friction resistance test is performed without grouting, and then a thixotropic slurry is injected into the soil on both sides and the bottom of the slider using a grouting assembly, and a three-sided friction resistance test is performed, and the drag reduction effect of the thixotropic slurry is analyzed and evaluated by comparing the change in the friction coefficient of the slider; The ratio of the three-sided friction resistance of the slider without grouting to the grouting friction resistance is k 2 , through k 2 The drag reduction effect of thixotropic mud is evaluated by numerical analysis. The specific expression is as follows: Formula (5) In formula (5), g is the acceleration due to gravity, M is the mass of the slider, m is the mass of the counterweight.

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