Grouting lease reduction effect test method
The rotary grouting rent reduction test device solves the problem of difficulty in evaluating the rent reduction effect of grout in pipe jacking construction, realizes accurate measurement and selection of grout effect, and improves construction efficiency.
Patent Information
- Application Number
- CN202511968497.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-24
- Publication Date
- 2026-04-17
AI Technical Summary
In pipe jacking construction, existing technologies cannot effectively determine the rent reduction effect of grout, making it impossible to select a suitable grout and affecting the construction results.
A rotary grouting rent reduction test device was adopted. Through components such as a confining pressure water tank, a pore pressure water tank, a grouting tank, and a test table, the pipe jacking construction process was simulated, the rent reduction effect of the grout was measured, and the torque sensor was used to detect the torque change during rotation to calculate the rent reduction rate.
It can accurately assess the rent reduction effect of grout, help select the right grout, and improve the efficiency and effectiveness of pipe jacking construction.
Smart Images
Figure CN121878121A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of pipe jacking construction testing technology, and in particular to a method for testing the effect of grouting rent reduction. Background Technology
[0002] In engineering construction, underground tunnels (including pipelines) need to be built. Existing tunnel construction methods include: shield tunneling, blasting, open-cut excavation, and pipe jacking. Pipe jacking is a trenchless construction method, a technology for laying pipelines (tunnels) with little or no excavation. Pipe jacking involves using the jacking force generated by jacking equipment within a working pit to overcome the friction between the pipeline and the surrounding soil, pushing the pipeline into the ground at the designed slope, and then removing the excavated soil. After one pipe section is pushed into the soil, the next section is installed and the process continues. The principle is to use the thrust from the main jacking cylinder and the pipeline itself, as well as intermediate sections, to advance the pipe section or tunneling machine (pipe jacking machine) from the starting shaft through the soil to the receiving shaft where it is lifted. The pipeline follows closely behind the pipe jacking machine, buried between the two pits. When there are construction interferences on the surface, making open-cut excavation inconvenient and the tunnel is small, pipe jacking is the optimal construction method (pipe jacking is not considered a rock-related geological condition). Pipe jacking construction has the following drawbacks: high friction during advancement leads to high resistance, making it unsuitable for long-distance tunnel construction. To address this, during pipe jacking, the jacking machine excavates a hole with a diameter equivalent to that of the joint to allow the pipe section to pass through. As the jacking machine advances, it radially compresses the hole, creating a predetermined distance of contraction. This results in a gap between the joint and the hole wall, into which grout is injected to lubricate and reduce the friction of the pipe section. However, the specific friction-reducing effect of the grout in the soil is unknown depending on the depth of the top layer and the soil type; that is, the friction-reducing ratio cannot be determined. In current construction practices, it would be best to determine the friction-reducing effect of the grout to better ascertain whether the grout meets the required level of friction reduction. Summary of the Invention
[0003] The present invention aims to provide a grouting rent reduction effect test method for obtaining the rent reduction effect of grout during pipe jacking construction, which solves the problem that the rent reduction effect of grout cannot be obtained during existing pipe jacking construction, thus making it impossible to know which grout is suitable.
[0004] To achieve the above-mentioned objectives, the present invention employs the following technology: a method for testing the effect of grouting rent reduction, characterized in that it is accomplished using a rotary grouting rent reduction testing device. The rotary grouting rent reduction testing device includes a confining pressure water tank, a pore pressure water tank, a grouting tank, and a test table. The test table has a sample support boss and a soil sample confining pressure cover fitted onto the sample support boss. The soil sample confining pressure cover is detachably and sealingly connected to the table, isolating a soil sample storage space on the table. A vertically positioned upper end located on the soil sample is rotatably connected to the sample support boss. A rotating shaft within the storage space has its upper end rotatably inserted into the soil sample cover plate. The shaft has a slurry outlet on its circumference and a slurry inlet at its lower end, connected to the outlet. The lower end of the shaft is connected to a rotary motor via a torque sensor. A connecting sleeve, sealingly fitted onto the lower end of the shaft, is attached to the lower surface of the tabletop. An annular dispensing chamber surrounds the shaft between the connecting sleeve and the shaft. The connecting sleeve has a grouting hole communicating with the annular dispensing chamber. This grouting hole is connected to the slurry outlet of a grouting tank via a slurry delivery pipe. A sample support protrusion is provided with… The system includes a perforated water inlet, a confining water inlet on the tabletop, and a water outlet on the soil sample cover plate. The soil sample cover plate is continuously connected to the tabletop via a tie rod. The water outlet of the confining water tank is connected to the confining water inlet via a confining water pipe. The water outlet of the perforated water tank is connected to the perforated water inlet via a perforated water pipe. The process for conducting the grouting rent reduction effect test is as follows: Step 1: Soil sample installation: Stack the soil samples on the sample support boss and wrap around the rotating shaft. Cover with the soil sample cover plate and then cover with the soil sample confining pressure cover. The soil sample confining pressure cover and the soil sample... The process involves three steps: First, creating a confining water storage space. Second, material preparation: water is added to the confining water tank and the pore pressure water tank, and grout is added to the grouting tank. Third, saturation: gas at pressure P1 is introduced into the confining water tank, gas at pressure P2 is introduced into the pore pressure water tank, and gas at pressure P3 is introduced into the grouting tank. This keeps the confining water pipe and the pore pressure water pipe open, while the grout delivery pipe remains disconnected. Water from the pore pressure water tank enters the sample cylinder through the pore pressure water pipe, permeates the sample, and finally flows through the outlet to the space between the soil sample and the soil sample confining cap. Water from the confining water tank enters the space between the soil sample and the soil sample confining cap through the confining water pipe. P2 is the soil pressure at the location where pipe jacking is required, P1 is the groundwater pressure at the location where pipe jacking is required, and P3 is the grouting pressure during construction. Saturation is completed when the liquid levels in the confining pressure tank and the pore pressure tank remain constant. Fourth step, consolidation: Gas with a pressure of P4 is introduced into the pore pressure tank, where P4 = P1 + P2. At this time, water permeates through the soil sample into the space between the soil sample and the soil sample confining cap, and then enters the confining pressure tank. Consolidation is completed when the liquid level in the confining pressure tank remains constant.Step 5, Dry Rotation: A rotary motor drives the shaft to rotate, and a torque sensor detects the dry rotation torque M1 of the shaft during rotation. Step 6, Grouting: A grouting gap is formed between the shaft and the soil sample, keeping the confining water pipe and the pore water pipe disconnected, while the grout delivery pipe remains open. The grout delivery pipe is closed when the grout volume in the grouting tank remains constant. Step 7, Wet Rotation: A rotary motor drives the shaft to rotate, and a torque sensor detects the wet rotation torque M2 of the shaft during rotation. Step 8, Calculating Rent Reduction Effect: The rent reduction rate is calculated using the formula (M1-M2) / M1. A higher rent reduction rate indicates a better rent reduction effect from the grout.
[0005] Preferably, the tabletop also includes a gantry with a cap lifting structure connected to the soil sample cap. After the test, the soil sample cap is detached from the tabletop, and then the cap lifting structure is used to lift the soil sample cap and remove the soil sample. Removing the soil sample cap is less strenuous.
[0006] Preferably, the circumferential surface of the portion of the rotating shaft that connects with the soil sample has a horizontally extending blind hole. A compression block and a spring with a channel for the compression block to move towards the inside of the blind hole are slidably connected within the blind hole. The outer end face of the compression block is cylindrical, and the radius of the cylinder containing the outer end face of the compression block is equal to the radius of the portion of the rotating shaft with the blind hole. The upper end face of the rotating shaft has a vertical hole penetrating the blind hole. The inner end face of the compression block is an upwardly inclined driving slope. When the outer end face of the compression block is located on the cylindrical surface of the rotating shaft, the inner end face of the compression block extends into the vertical hole. A driving block that compresses the inner end face of the compression block passes through the vertical hole. The driving block is connected to a compression block lifting structure. The process of forming the grouting gap in step six is as follows: the driving block is driven to descend by the compression block lifting structure. The distance by which the driving block drives the compression block to extend out of the rotating shaft is equal to the width of the grouting gap, causing the rotary motor to drive the rotating shaft to rotate. Thus, the grouting gap is formed between the soil sample and the rotating shaft through the portion of the compression block protruding from the rotating shaft. It is convenient and accurate to form grouting gaps.
[0007] Preferably, the blind hole has a closed-end infusion tank on its sidewall. The driving block closes the infusion tank to form the slurry outlet section. The rotating shaft has an inlet section connecting the blind hole and the slurry inlet. The driving block has a connecting section connecting the outlet section and the inner end face of the driving block. The spring can drive the outer end of the driving block to retract into the blind hole, exposing the outer end of the infusion tank to form the slurry outlet. This provides a consistent structure for the grouting channel. In use, when the extrusion block retracts into the blind hole under the action of the spring until the infusion tank is exposed, the slurry can be output; otherwise, the slurry delivery pipe is disconnected. The inference control structure of the slurry delivery pipe is integrated into the slurry gap forming structure, resulting in a compact structure.
[0008] Preferably, the infusion tank is located on the side wall of the front end of the blind hole along the rotation direction of the axis. This reduces the damage to the soil sample caused by grouting and improves the accuracy of the sample.
[0009] Preferably, the outer end of the end face of the drive block located at the front end of the shaft in the rotation direction is provided with a squeezing inclined surface, and the outer end of the squeezing inclined surface is inclined towards the rear end in the rotation direction of the shaft. This allows the force of the squeezing block along the radial direction of the soil sample to be larger when the grouting gap is formed, more accurately simulating the squeezing situation of the soil during actual construction, and making the obtained sample data more accurate.
[0010] Preferably, when the distance the drive block extends out of the blind hole is equal to the grouting thickness during pipe jacking, the inner end of the extrusion ramp is in contact with the circumferential surface of the rotating shaft. This ensures sample accuracy.
[0011] Preferably, the extrusion block lifting structure includes a cover plate covering the upper end of the vertical hole and a lifting cylinder connected to the inner surface of the cover plate. The lifting cylinder is a double-stroke cylinder and is connected to the drive block. During grouting, the lifting cylinder is in a retracted state during both strokes; when forming the grouting gap, the lifting cylinder is in an extended state during both strokes; and during dry and wet operation, the lifting cylinder is in a state where it is extended for only one stroke.
[0012] Preferably, the sample also includes a soil sample storage sleeve with its lower end fitted onto the sample support protrusion. The soil sample storage sleeve is a flexible structure, and a raised ring is provided on the lower surface of the soil sample cover plate, which passes through the soil sample storage sleeve. This prevents damage to the integrity of the soil sample and improves sample accuracy.
[0013] Preferably, the sample also includes a lower sand layer laid on the sample support protrusion within the soil sample storage sleeve and an upper sand layer covering the soil sample within the soil sample storage sleeve. This prevents water from eroding the sample and improves the accuracy of the test.
[0014] The present invention has the following beneficial effects: it can test the construction effect of the grout, thereby making it easier to predict what kind of grout needs to be used during pipe jacking construction to achieve the rent reduction requirements. Attached Figure Description
[0015] Figure 1 This is a flowchart of the present invention; Figure 2 This is a schematic diagram of the rotary grouting rent reduction test device of the present invention; Figure 3 yes Figure 2 A magnified view of a portion of point A; Figure 4 yes Figure 3 Schematic diagram of B-B section; Figure 5 yes Figure 4 A magnified view of a portion of point C.
[0016] In the diagram: 1. Confining pressure water tank; 2. Hole pressure water tank; 3. Grouting tank; 4. Test table; 5. Sample support boss; 6. Soil sample confining pressure cover; 7. First bolt; 8. Rotating shaft; 9. Soil sample upper cover plate; 11. Grout inlet; 12. Torque sensor; 13. Rotary motor; 14. Reducer; 15. Connecting sleeve; 16. Annular liquid distribution chamber; 17. Grouting hole; 18. Grout delivery pipe; 19. Water outlet; 20. Tie rod; 21. Confining pressure water pipe; 22. Hole pressure water pipe; 23. Soil sample; 24. Gantry; 25. Lifting structure of cover, 26. Blind hole, 27. Extrusion block, 28. Spring, 29. Outer end face of extrusion block, 30. Vertical hole, 31. Inner end face of extrusion block, 32. Drive block, 33. Lifting structure of extrusion block, 34. Cover plate, 35. Lifting cylinder, 36. Liquid inlet tank, 37. Slurry outlet channel inlet section, 38. Slurry outlet channel connecting section, 39. Outer end of liquid inlet tank, 40. Extrusion slope, 41. Inner end of extrusion slope, 42. Soil sample storage sleeve, 43. Convex ring, 44. Lower sand layer, 45. Upper sand layer. Detailed Implementation
[0017] The present invention will now be described in conjunction with the accompanying drawings and specific embodiments, wherein the anchor rod is inclined with one end higher than the other end, which is connected to the inner retaining wall, and the lower end of the anchor rod is lower than the bottom of the inner pit.
[0018] See Figures 1 to 5The grouting rent reduction effect test method is carried out using a rotary grouting rent reduction test device. The rotary grouting rent reduction test device includes a confining pressure water tank 1, a pore pressure water tank 2, a grouting tank 3, and a test table 4. The test table has a sample support boss 5 and a soil sample confining pressure cover 6 fitted onto the sample support boss. The soil sample confining pressure cover is fixed to the table by a first bolt 7, and the soil sample confining pressure cover and the table are sealed together. The soil sample confining pressure cover isolates a soil sample storage space on the table. A vertically placed rotating shaft 8, with its upper end located within the soil sample storage space, is rotatably connected to the sample support boss. The upper end of the rotating shaft rotatably passes through a soil sample cover plate 9. A grout outlet is provided on the circumference of the rotating shaft, and a grout inlet 11 connected to the grout outlet is provided at the lower end of the rotating shaft. The lower end of the rotating shaft is connected to a rotary motor 13 via a torque sensor 12. The rotary motor is equipped with a reducer 14. A connecting sleeve 15, sealed and fitted onto the lower end of the rotating shaft, is attached to the lower surface of the desktop. An annular liquid distribution chamber 16 surrounds the rotating shaft between the connecting sleeve and the shaft. The connecting sleeve has a grouting hole 17 communicating with the annular liquid distribution chamber. The grouting hole is connected to the grout outlet of the grouting tank via a grout delivery pipe 18. A pore pressure water inlet is provided on the sample support protrusion, a confining pressure water inlet is provided on the desktop, and a water outlet 19 is provided on the soil sample cover plate. The soil sample cover plate is detachably connected to the desktop via a tie rod 20. The outlet of the confining pressure water tank is connected to the confining pressure water inlet via a confining pressure water pipe 21. The outlet of the pore pressure water tank is connected to the pore pressure water inlet via a pore pressure water pipe 22.
[0019] The process of conducting the grouting rent reduction effect test is as follows: Step 1: Soil sample installation: Stack soil samples 23 on the sample support platform and wrap around the rotating shaft. Cover with the soil sample top cover and then cover with the soil sample confining pressure cover, forming a confining pressure water storage space between the soil sample confining pressure cover and the soil sample. Step 2: Material preparation: Fill the confining pressure water tank and the pore pressure water tank with water, and fill the grouting tank with grout. Step 3: Saturation: Input gas at pressure P1 into the confining pressure water tank, gas at pressure P2 into the pore pressure water tank, and gas at pressure P3 into the grouting tank. Keep the confining pressure water pipe and the pore pressure water pipe open, and keep the grout delivery pipe disconnected. Water in the pore pressure water tank enters the sample cylinder through the pore pressure water pipe, permeates through the sample, and finally flows through the outlet to the space between the soil sample and the soil sample confining pressure cover. Water in the confining pressure water tank enters the space between the soil sample and the soil sample confining pressure cover through the confining pressure water pipe. P2 is the soil pressure at the location where pipe jacking is required, P1 is the groundwater pressure at the location where pipe jacking is required, and P3 is the grouting pressure during construction. Saturation is complete when the liquid levels in the confining pressure tank and the pressure tank remain constant. Fourth step: Consolidation: Introduce gas at pressure P4 into the pressure tank, where P4 = P1 + P2, at this point, water seeps through the soil sample into the space between the soil sample and the soil sample cap, and then enters the confining pressure tank. When the liquid level in the confining pressure tank remains constant, consolidation is complete. Step 5, Dry rotation: The rotary motor drives the shaft to rotate, and the dry rotation torque M1 of the shaft is detected by the torque sensor. Step 6, Grouting: A grouting gap is formed between the shaft and the soil sample, keeping the confining pressure water pipe and the pore pressure water pipe disconnected, while keeping the grout delivery pipe open. When the grout volume in the grouting tank remains constant, the grouting pipe is closed. Step 7, Wet rotation: The rotary motor drives the shaft to rotate, and the wet rotation torque M2 of the shaft is detected by the torque sensor. Step 8, Calculate the rent reduction effect: The rent reduction rate is calculated according to the formula (M1-M2) / M1. The larger the rent reduction rate, the better the rent reduction effect of the grout.
[0020] The tabletop also includes a gantry 24, on which a pressure cap lifting structure 25 connected to the soil sample pressure cap is installed. A horizontally extending blind hole 26 is provided on the circumferential surface of the part of the rotating shaft that connects with the soil sample. A compression block 27 and a spring 28 with a channel for the compression block to move towards the inside of the blind hole are slidably connected within the blind hole. The outer end face 29 of the compression block is a cylindrical surface, and the radius of the cylinder containing the outer end face of the compression block is equal to the radius of the part of the rotating shaft where the blind hole is located. A vertical hole 30 penetrating the blind hole is provided on the upper end face of the rotating shaft. The inner end face 31 of the compression block is an upwardly inclined driving slope. When the outer end face of the compression block is located on the cylindrical surface of the rotating shaft, the inner end face of the compression block extends into the vertical hole. A driving block 32 that compresses the inner end face of the compression block passes through the vertical hole. The driving block is connected to the compression block lifting structure 33. The extrusion block lifting structure includes a cover plate 34 covering the upper end of the vertical hole and a lifting cylinder 35 connected to the inner surface of the cover plate. The lifting cylinder is a double-stroke cylinder and is connected to the drive block. The process of forming the grouting gap in the sixth step is as follows: the drive block is driven to descend by the extrusion block lifting structure. The distance by which the drive block drives the extrusion block to extend out of the rotating shaft is equal to the width of the grouting gap, causing the rotary motor to drive the rotating shaft to rotate. Thus, the grouting gap is formed between the soil sample and the rotating shaft through the part of the extrusion block protruding from the rotating shaft. The blind hole has a closed-end infusion trough 36 on its side wall (there are multiple infusion troughs, specifically six, distributed vertically). The drive block closes the infusion trough to form the slurry outlet section. The rotating shaft has an inlet section 37 connecting the blind hole and the slurry inlet. The drive block has a slurry outlet section 38 connecting the outlet section and the inner end face of the drive block. A spring can drive the outer end of the drive block to retract into the blind hole, so that the outer end 39 of the infusion trough is exposed in the blind hole to form the slurry outlet. The infusion trough is located on the side wall of the front end of the blind hole along the rotation direction of the rotating shaft. The outer end of the end face of the drive block at the front end in the rotation direction of the rotating shaft has a pressing slope 40, and the outer end of the pressing slope is inclined towards the rear end in the rotation direction of the rotating shaft. The drive block extends... When the distance from the blind hole is equal to the grouting thickness during pipe jacking, the inner end 41 of the extrusion slope is connected to the circumference of the rotating shaft. During grouting, the lifting cylinder is in a state of contraction in both strokes; when forming the grouting gap, the lifting cylinder is in a state of extension in both strokes; during dry and wet rotation, the lifting cylinder is in a state of extension in only one stroke. It also includes a soil sample storage sleeve 42 with its lower end fitted onto the sample support boss. The soil sample storage sleeve is a flexible structure, and a raised ring 43 passing through the soil sample storage sleeve is provided on the lower surface of the soil sample cover plate. It also includes a lower sand layer 44 laid on the sample support boss and located inside the soil sample storage sleeve, and an upper sand layer 45 covering the soil sample and located inside the soil sample storage sleeve.
Claims
1. A method for testing the rent reduction effect of grouting, characterized in that, This is accomplished using a rotary grouting pressure reduction test device, which includes a confining pressure water tank, a pore pressure water tank, a grouting tank, and a test table. The test table has a sample support boss and a soil sample confining pressure cover fitted onto the sample support boss. The soil sample confining pressure cover is detachably and sealingly connected to the table, isolating a soil sample storage space on the table. A vertically positioned rotating shaft, with its upper end located within the soil sample storage space, is rotatably connected to the sample support boss. The upper end of the rotating shaft rotatably passes through the soil sample cover. Inside the plate, a slurry outlet is provided on the circumference of the rotating shaft, and a slurry inlet communicating with the slurry outlet is provided at the lower end of the rotating shaft. The lower end of the rotating shaft is connected to a rotary motor via a torque sensor. A connecting sleeve, which is sealed and fitted onto the lower end of the rotating shaft, is connected to the lower surface of the tabletop. An annular liquid distribution chamber surrounding the rotating shaft is provided between the connecting sleeve and the rotating shaft. The connecting sleeve has a grouting hole communicating with the annular liquid distribution chamber. The grouting hole is connected to the slurry outlet of the grouting tank via a slurry delivery pipe. A pressure water inlet is provided on the sample support protrusion, and a confining pressure water inlet is provided on the tabletop. The soil sample cover plate is equipped with a water outlet, and the soil sample cover plate is continuously connected to the tabletop via a tie rod. The water outlet of the confining pressure tank is connected to the confining pressure water inlet via a confining pressure water pipe, and the water outlet of the pore pressure water tank is connected to the pore pressure water inlet via a pore pressure water pipe. The process of conducting the grouting rent reduction effect test is as follows: Step 1, Soil sample installation: Stack the soil sample on the sample support boss and wrap it around the rotating shaft, cover it with the soil sample cover plate, and cover it with the soil sample confining pressure cover. A confining pressure water storage space is formed between the soil sample confining pressure cover and the soil sample. Step 2, Material Preparation: Fill the confining pressure tank and the pore pressure tank with water, and fill the grouting tank with grout. Step 3, Saturation: Input gas at pressure P1 into the confining pressure tank, gas at pressure P2 into the pore pressure tank, and gas at pressure P3 into the grouting tank. Keep the confining pressure pipe and the pore pressure pipe open, while keeping the grout delivery pipe closed. Water from the pore pressure tank enters the sample cylinder through the pore pressure pipe, permeates the sample, and finally flows through the outlet between the soil sample and the soil sample confining cap. Water from the confining pressure tank enters the space between the soil sample and the soil sample confining cap through the confining pressure pipe. P2 is the soil pressure at the location where pipe jacking is required, P1 is the groundwater pressure at the location where pipe jacking is required, and P3 is the grouting pressure during construction. Saturation is complete when the liquid levels in the confining pressure tank and the pressure tank remain constant. Fourth step, consolidation: Gas at pressure P4 is introduced into the pressure tank, where P4 = P1 + P2. At this time, water permeates through the soil sample into the space between the soil sample and the soil sample cap, and then enters the confining pressure tank. Consolidation is complete when the liquid level in the confining pressure tank remains constant. Fifth step, dry rotation: A rotary motor drives the shaft to rotate, and a torque sensor detects the dry rotation torque M1 of the shaft during rotation.Step 6, Grouting: A grouting gap is formed between the rotating shaft and the soil sample, keeping the confining water pipe and the pore water pipe disconnected, while the grout delivery pipe remains open. The grouting pipe is closed when the grout volume in the grouting tank remains constant. Step 7, Wet Rotation: A rotary motor drives the rotating shaft to rotate, and a torque sensor detects the wet rotation torque M2 of the shaft during rotation. Step 8: Calculate the rent reduction effect: Calculate the rent reduction rate according to the formula (M1-M2) / M1. The larger the rent reduction rate, the better the rent reduction effect of the slurry.
2. The method for testing the rent reduction effect of grouting according to claim 1, characterized in that, The tabletop also includes a gantry, on which a cap lifting structure is connected to the soil sample cap. After the test, the soil sample cap is detached from the tabletop, and then the cap lifting structure is used to lift the soil sample cap and remove the soil sample. Removing the soil sample cap is effortless.
3. The method for testing the rent reduction effect of grouting according to claim 1, characterized in that, A horizontally extending blind hole is provided on the circumferential surface of the part of the rotating shaft that connects with the soil sample. A squeezing block and a spring with a channel for the squeezing block to move toward the inside of the blind hole are slidably connected in the blind hole. The outer end face of the squeezing block is a cylindrical surface, and the radius of the cylinder on which the outer end face of the squeezing block is located is equal to the radius of the part of the rotating shaft with the blind hole. A vertical hole penetrating the blind hole is provided on the upper end face of the rotating shaft. The inner end face of the squeezing block is an upwardly inclined driving slope. When the outer end face of the squeezing block is located on the cylindrical surface on which the circumferential surface of the rotating shaft is located, the inner end face of the squeezing block extends into the vertical hole. A driving block that squeezes the inner end face of the squeezing block is installed in the vertical hole. The driving block is connected to the squeezing block lifting structure. The process of forming the grouting gap in the sixth step is as follows: the driving block is driven to descend by the squeezing block lifting structure. The distance by which the driving block drives the squeezing block to extend out of the rotating shaft is equal to the width of the grouting gap, so that the rotary motor drives the rotating shaft to rotate, thereby forming the grouting gap between the soil sample and the rotating shaft through the part of the squeezing block protruding from the rotating shaft.
4. The method for testing the rent reduction effect of grouting according to claim 3, characterized in that, The blind hole has a closed-end infusion tank on its sidewall. The driving block closes the infusion tank to form the slurry outlet section. The rotating shaft has an inlet section connecting the blind hole and the slurry inlet. The driving block has a slurry outlet connecting section connecting the outlet section and the inner end face of the driving block. The spring can drive the outer end of the driving block to retract into the blind hole, thus exposing the outer end of the infusion tank inside the blind hole to form the slurry outlet. This provides a specific structure for the grouting channel.
5. The method for testing the rent reduction effect of grouting according to claim 4, characterized in that, The infusion tank is located on the side wall at the front end of the blind hole along the rotation direction of the shaft.
6. A test method for grouting rent reduction effect according to claim 4 or 5, characterized in that, The outer end of the end face of the drive block located at the front end of the rotating shaft in the direction of rotation is provided with a pressing slope, and the outer end of the pressing slope is inclined toward the rear end of the rotating shaft in the direction of rotation.
7. The method for testing the rent reduction effect of grouting according to claim 6, characterized in that, When the distance from which the drive block extends out of the blind hole is equal to the grouting thickness during pipe jacking, the inner end of the extrusion inclined surface is connected to the circumference of the rotating shaft.
8. A test method for grouting rent reduction effect according to claim 4 or 5, characterized in that, The extrusion block lifting structure includes a cover plate covering the upper end of the vertical hole and a lifting cylinder connected to the inner surface of the cover plate. The lifting cylinder is a double-stroke cylinder and is connected to the drive block. During grouting, the lifting cylinder is in a state of contraction in both strokes. When forming the grouting gap, the lifting cylinder is in a state of extension in both strokes. During dry and wet rotation, the lifting cylinder is in a state of extension of only one stroke.
9. A test method for grouting rent reduction effect according to claim 1, 2, 3, 4, or 5, characterized in that, It also includes a soil sample storage sleeve with its lower end fitted onto the sample support protrusion. The soil sample storage sleeve is a flexible structure, and a protruding ring is provided on the lower surface of the soil sample cover plate, which passes through the soil sample storage sleeve.
10. The method for testing the rent reduction effect of grouting according to claim 9, characterized in that, It also includes a lower sand layer located inside the soil sample storage sleeve and laid on the sample support protrusion, and an upper sand layer located inside the soil sample storage sleeve covering the soil sample.