Model test device and method for stratum excavation and grouting reinforcement

Abstract

The invention relates to the technical field of underground engineering groove wall stability physical simulation, and discloses a model test device and method for stratum excavation and grouting reinforcement, and the model test device comprises a grooving construction module, a grouting support module and a dynamic monitoring module. The device adopts a pressing plate method to simulate a grooving excavation process, so that the device conforms to an actual excavation working condition from top to bottom; a servo motor drives a power lead screw to drive a model groove to move downwards, so that a free face is formed in a sand layer, and the actual excavation working condition is simulated; a water tank for storing fresh slurry is pressurized by using an air compressor, so that the slurry overflows from the hollow model groove section, and the permeation and invasion process of the slurry is simulated; and a water and soil pressure gauge and a matched acquisition device are arranged in the sand layer, and a soil displacement field is obtained by utilizing a particle image velocity measurement system, so that the visualization of the whole process of excavation-grouting-invasion is realized. It is ensured that simulation results are highly matched with actual working conditions, and accuracy and reliability are improved.

Description

Technical Field

[0001] This invention relates to the field of physical simulation technology for the stability of underground engineering trench walls, and in particular to a model test device and method for stratum excavation and grouting reinforcement. Background Technology

[0002] In modern civil engineering, diaphragm walls are widely used as a highly efficient foundation pit support structure due to their advantages in water tightness and support capacity. However, with the increase in foundation pit depth and the complexity of geological conditions, the challenges faced during the construction of diaphragm walls are becoming increasingly severe. Among them, the problem of trench wall instability is particularly prominent and has become a key factor restricting the construction quality and safety of diaphragm walls.

[0003] Although physical simulation models are available for simulating and analyzing the stability of trench walls during the construction of diaphragm walls, they all have significant limitations.

[0004] First, the "slab-pulling method" commonly used in existing physical simulation models typically simulates bottom-up excavation conditions, which differs significantly from the top-down excavation process commonly seen in actual construction. Because the "slab-pulling method" cannot accurately reflect the gradual release of soil stress and the resulting stress redistribution during top-down excavation, it is difficult to realistically simulate the mechanical response and deformation behavior of the trench wall under actual construction conditions. Second, when simulating synchronous control techniques such as excavation-grouting-intrusion, existing models often fail to achieve precise synchronous control, leading to significant deviations between simulation results and actual working conditions.

[0005] Therefore, those skilled in the art urgently need to develop a model testing device and method for stratum excavation and grouting reinforcement. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by proposing a model test device and method for stratum excavation and grouting reinforcement.

[0007] Based on one objective of the present invention, the following technical solution is proposed: a model test device for stratum excavation and grouting reinforcement, comprising a trenching construction module, a grouting support module and a dynamic monitoring module; The trenching construction module includes a model box with an opening at the top, a partition at half the height of the interior of the model box, a loading frame above the model box, and a loading device at the bottom of the loading frame. The grouting support module includes a water tank, and a pressure stabilizing device and an air compressor are connected in sequence on the right side of the water tank; the loading device includes a lifting mechanism connected to the loading frame, and a model groove section is provided below the lifting mechanism. The model groove section has a hollow structure and a grouting port at the top. The grouting port is connected to the water tank through a water inlet pipe. The side wall of the model groove section is in close contact with the model box. The partition consists of a horizontal plate and a vertical plate. A sand layer is laid in the area enclosed by the horizontal plate, the model groove section, and the model box. The vertical plate is located directly below the model groove section and has a sliding groove structure on the plate for the model groove section to slide up and down. The dynamic monitoring module includes a particle image velocity measurement (PIV) system, a soil pressure gauge, and a matching acquisition device.

[0008] Preferably, the sidewall of the vertical plate is covered with a polytetrafluoroethylene film, the vertical plate has a flow hole, the bottom of the horizontal plate is provided with a mud pool, the flow hole and the mud pool are connected by a discharge pipe, and the discharge pipe is provided with a pneumatic valve.

[0009] Preferably, the lifting mechanism includes a servo motor, the output end of which is connected to a power lead screw, and the bottom of the power lead screw is threadedly connected to a loading head, which is fixedly connected to the top of the model groove section.

[0010] Preferably, the servo motor and the power lead screw are connected via a continuously variable transmission and a worm gear reducer.

[0011] Preferably, the particle image velocimetry (PIV) system includes a high-definition motion camera, which monitors the front, right, and top surfaces of the model box; the soil pressure gauge and its associated acquisition device are installed in the sand layer.

[0012] Preferably, the front and right facades of the model box are made of transparent plexiglass panels, while the remaining facades and bottom are made of steel plates, and the sidewalls of the model groove section are in close contact with the end of the model box and the transparent plexiglass panels.

[0013] Based on another objective of this invention, a model test method for stratum excavation and grouting reinforcement is proposed, comprising the following steps: S1. The hollow model groove section is pressed down by the power screw driven by the servo motor, exposing the free surface of the sand layer step by step. S2. Use an air compressor to pressurize the water tank, so that fresh mud slurry continuously overflows from the model trench to the excavated free face, and the mud slurry overflowing from the trench comes into contact with the surface of the sand layer. S3. Open the pneumatic valve of the mud pool at the bottom of the model box to drive the mud into the mud pool, recover excess mud, and promote mud circulation. S4. Using an integrated particle image velocity (PIV) system, a soil and water pressure sensor, and supporting acquisition devices, the surface subsidence and sand layer pore pressure changes are monitored in real time.

[0014] Preferably, in step S2, the hollow model groove section is pressed down at a rate of 15 mm / min; in step S4, sodium fluorescein tracer is added to the mud slurry, and the mud movement front is obtained by observing the migration of the tracer.

[0015] Preferably, in step S4, a high-definition motion camera monitors the front, right, and top surfaces of the model box to monitor the changes in surface subsidence and sand pore pressure in real time.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. This device uses the "pressure plate method" to simulate the trenching process, conforming to the actual top-down excavation conditions. A servo motor drives a power screw to move the model trench downwards, creating a free surface in the sand layer, simulating actual excavation conditions. An air compressor pressurizes a tank storing fresh slurry, causing the slurry to overflow from the hollow model trench section. The overflowing slurry contacts the exposed sand layer excavation surface, simulating the infiltration and penetration process of the mud slurry. By adjusting the air compressor's pressure setting, the mud slurry injection rate can be controlled, thus achieving synchronous intelligent control of trenching and mud wall protection. It accurately simulates top-down excavation conditions, realistically reflecting the gradual release and redistribution of soil stress, and precisely presenting the mechanical response and deformation behavior of the trench wall under actual construction conditions.

[0017] 2. In this invention patent, sodium fluorescein tracer is added to the slurry. By observing the migration of the tracer, the mud movement front is obtained. Water and soil pressure gauges and matching acquisition devices are deployed in the sand layer to obtain the soil displacement field using a particle image velocimetry (PIV) system. This enables visualization and accurate simulation of the entire process of excavation-grouting-intrusion, ensuring that the simulation results are highly consistent with the actual working conditions and improving the accuracy and reliability of the simulation. Attached Figure Description

[0018] Figure 1 It is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the structure of the model box described in this invention; Figure 3 This is a schematic diagram of the structure of the groove segment model described in this invention.

[0019] In the diagram: 1. Model box; 2. Loading frame; 3. Sand layer; 4. Servo motor; 41. Power lead screw; 42. Loading head; 5. Camera; 6. Transparent plexiglass plate; 7. Pneumatic valve; 8. Mud tank; 9. Air compressor; 10. Pressure stabilizing device; 11. Water tank; 12. Grouting port; 13. Baffle plate; 14. Model groove section; 15. Flow hole. Detailed Implementation

[0020] The present invention will now be clearly described with reference to the accompanying drawings and specific embodiments. This description is merely illustrative and is not intended to limit the scope of the invention. Any modifications, equivalent substitutions, or improvements made by those skilled in the art based on the embodiments of the present invention without inventive effort to obtain all other embodiments should be included within the scope of protection of the present invention.

[0021] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0022] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0023] Example 1 Please see Figure 1-Figure 3 The present invention provides a model test device for stratum excavation and grouting reinforcement, including a trenching construction module, a grouting support module and a dynamic monitoring module; The trenching construction module includes a model box 1, with an opening at the top of the model box 1, a partition 13 at half height inside the model box 1, a loading frame 2 above the model box 1, and a loading device at the bottom of the loading frame 2. The grouting support module includes a water tank 11, with a pressure stabilizing device 10 and an air compressor 9 connected sequentially to the right side of the water tank 11. The loading device includes a lifting mechanism connected to the loading frame 2. Below the lifting mechanism is a model trough section 14, which is a hollow structure with a grouting port 12 at the top. The grouting port 12 is connected to the water tank 11 via a water inlet pipe. The sidewalls of the model trough section 14 are in close contact with the model box 1. The front and right facades of the model box 1 are made of transparent plexiglass panels 6, while the remaining facades and bottom are made of steel plates. The sidewalls of the model trough section 14 are in close contact with the ends of the model box 1 and the transparent plexiglass panels 6. The partition 13 consists of a horizontal plate and a vertical plate. A sand layer 3 is laid in the area enclosed by the horizontal plate, the model groove section 14 and the model box 1. The vertical plate is located directly below the model groove section 14 and has a sliding groove structure on the plate for the model groove section 14 to slide up and down. The dynamic monitoring module includes a particle image velocity measurement (PIV) system, a water and soil pressure gauge and a matching acquisition device.

[0024] The servo motor 4 drives the power screw 41 to press down the hollow model trench section 14 at a rate of 15 mm / min. The "pressure plate method" is used to expose the free surface of the sand layer step by step, simulating the trenching process from top to bottom in real engineering. Simultaneously pressurize the water tank 11 using the air compressor 9, continuously injecting fresh mud into the model trench section 14, so that the fresh mud continuously overflows from the model trench section 14 to the excavated free face. The mud overflowing from the trench section can contact the surface of the sand layer, simulating the mud penetration effect.

[0025] Furthermore, the sidewalls of the vertical plate are covered with a PTFE film, and a flow hole 15 is provided on the vertical plate. A mud pool 8 is provided at the bottom of the horizontal plate. The flow hole 15 and the mud pool 8 are connected through a discharge pipe, and a pneumatic valve 7 is provided on the discharge pipe.

[0026] Open the pneumatic valve 7 of the mud tank 8 at the bottom of the model box 1 to drive the mud into the mud tank 8, recover excess mud, promote mud circulation to reduce mud segregation, and achieve synchronous control of mud wall protection during trenching.

[0027] Furthermore, the lifting mechanism includes a servo motor 4, the output end of which is connected to a power lead screw 41, and the bottom of the power lead screw 41 is threadedly connected to a loading head 42, which is fixedly connected to the top of the model groove section 14; the servo motor 4 and the power lead screw 41 are connected through a continuously variable transmission and a worm gear reducer.

[0028] The output shaft of the servo motor 4 is rigidly connected to the input shaft of the continuously variable transmission (CVT) via a coupling. The output shaft of the CVT is then connected to the input shaft of the worm gear reducer via a coupling. The output shaft of the worm gear reducer is fixedly connected to one end of the power lead screw 41. The servo motor 4 provides the initial rotational power. The CVT can adjust the speed, such as changing the output speed, to adapt to the speed requirements under different working conditions. The worm gear reducer further reduces the speed and amplifies the torque. When the worm gear reducer drives the power lead screw 41 to rotate, the loading head 42 on the lead screw converts the rotational motion into axial linear motion due to the screw's helix, directly pushing the model groove section 14 downward in the vertical direction.

[0029] Furthermore, the Particle Image Velocity (PIV) system includes a high-definition motion camera 5, which monitors the front, right, and top surfaces of the model box 1. A soil pressure gauge and its associated acquisition device are installed in the sand layer 3, and the associated acquisition device collects the soil pressure gauge data in real time.

[0030] During this process, an integrated particle image velocimetry (PIV) system, soil and water pressure sensors, and supporting data acquisition devices were used. Sensors were deployed according to the key monitoring areas. Three high-definition motion cameras (5) monitored the front, right, and top surfaces of the model box. Soil and water pressure sensors were deployed in the sand layer (3), specifically pore water pressure gauges (10 measuring points) and soil pressure gauges (6 measuring points) to monitor pore pressure changes and soil stress distribution in the sand layer (3) in real time. The collected data was transmitted to the central control system via a multi-channel acquisition device. The three high-definition motion cameras (5) continuously captured soil deformation on the front, right, and top surfaces of the model box at a high frame rate, while simultaneously recording the migration trajectory of sodium fluorescein tracer in the mud.

[0031] The accompanying data acquisition device uses DaVis 8.0 series image processing software to calculate the soil displacement and velocity fields using tracer particles (sodium fluorescein) through a series of continuously captured images, generating a dynamic spectrum of soil deformation, and then performing correlation analysis with sensor data.

[0032] The aforementioned soil and water pressure sensor is model P306S-01, with a diameter of 6mm, a height of 2.5mm, a range of 100kg, and an accuracy of 2±0.01mV.

[0033] The aforementioned acquisition device uses Davis 8.0 series image processing software. Davis 8.0 mainly consists of a computer, analysis software, electronic equipment, external trigger signal digital-to-analog converter, and TTL input / output card. Davis 8.0 has a built-in digital-to-analog converter, providing analog-to-digital conversion and signal amplification functions.

[0034] The aforementioned high-definition action camera uses a SONY research-grade chip, with a resolution of 2489 pixels × 2091 pixels, a pixel size of 3.45μm × 3.45μm, an exposure time of 100μs × 80ms, a sampling rate of up to 200fps, and a maximum sampling frequency of 14.5Hz. It utilizes Camli... <x>The dedicated nk interface meets the measurement accuracy requirements of the experiment and provides hardware support for the successful completion of the experiment.

[0035] Sodium fluorescein tracer was added to the slurry to mark the slurry movement trajectory using its colorimetric properties. When sodium fluorescein penetrates into the sand layer with the slurry, it exhibits a fluorescent effect under light, clearly showing the slurry intrusion path and diffusion range. Three high-definition motion cameras were deployed to monitor the front, right, and top surfaces of the model box, respectively. The cameras continuously captured images at a high frame rate, recording the entire process of slurry overflowing from the model tank, contacting the sand layer, and penetrating and diffusing, capturing the slurry movement front and soil deformation process in real time.

[0036] The soil motion patterns were then obtained using a non-contact, full-field optical particle image velocimetry (PIV) system from the German company LaVision. The DaVis 8.0 series software was used to analyze the image sequences captured by the camera using PIV analysis. By tracking the displacement of sodium fluorescein tracer particles, the velocity and displacement fields of the mud movement front and soil deformation were calculated.

[0037] Example 2 The present invention also provides a model test method for stratum excavation and grouting reinforcement, including the model test device for stratum excavation and grouting reinforcement in the above embodiments, and further including the following steps: S1. The servo motor 4 drives the power screw 41 to press down the hollow model groove section 14, exposing the free surface of the sand layer 3 step by step. S2. Pressurize the water tank 11 using the air compressor 9 so that fresh mud slurry continuously overflows from the model trench section 14 to the excavated free face, and the mud slurry overflowing from the trench section comes into contact with the surface of the sand layer 3. S3. Open the pneumatic valve 7 of the mud tank 8 at the bottom of the model box 1 to drive the mud into the mud tank 8, recover excess mud, and promote mud circulation. S4. Using an integrated particle image velocity (PIV) system, soil and water pressure sensor, and supporting acquisition device, the surface subsidence and the changes in pore pressure of the sand layer are monitored in real time.

[0038] Furthermore, in step S2, the hollow model tank section 14 is pressed down at a rate of 15 mm / min; in step S4, sodium fluorescein tracer is added to the mud slurry, and the mud movement front is obtained by observing the migration of the tracer.

[0039] Furthermore, in step S4, the high-definition motion camera 5 monitors the front, right, and top surfaces of the model box 1 to monitor the changes in surface subsidence and sand pore pressure in real time.

[0040] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.< / x>

Claims

1. A model test device for stratum excavation and grouting reinforcement, characterized in that: It includes trenching construction modules, grouting support modules, and dynamic monitoring modules; The trenching construction module includes a model box (1), the top of the model box (1) is provided with an opening, the interior half height of the model box (1) is provided with a partition (13), the top of the model box (1) is provided with a loading frame (2), and the bottom of the loading frame (2) is provided with a loading device; The grouting support module includes a water tank (11), and a pressure stabilizing device (10) and an air compressor (9) are connected in sequence on the right side of the water tank (11); the loading device includes a lifting mechanism connected to the loading frame (2), and a model groove section (14) is provided below the lifting mechanism. The model groove section (14) is a hollow structure and has a grouting port (12) at the top. The grouting port (12) is connected to the water tank (11) through a water inlet pipe. The side wall of the model groove section (14) is close to the model box (1). The partition (13) is composed of a horizontal plate and a vertical plate. A sand layer (3) is laid in the area enclosed by the horizontal plate, the model groove section (14) and the model box (1). The vertical plate is located directly below the model groove section (14) and has a sliding groove structure on the plate for the model groove section (14) to slide up and down. The dynamic monitoring module includes a particle image velocity measurement (PIV) system, a soil pressure gauge and a matching acquisition device.

2. The model test device for stratum excavation and grouting reinforcement according to claim 1, characterized in that: The side wall of the vertical plate is covered with a PTFE film. A flow hole (15) is provided on the vertical plate. A mud tank (8) is provided at the bottom of the horizontal plate. The flow hole (15) is connected to the mud tank (8) through a discharge pipe. A pneumatic valve (7) is provided on the discharge pipe.

3. The model test device for stratum excavation and grouting reinforcement according to claim 1, characterized in that: The lifting mechanism includes a servo motor (4), the output end of which is connected to a power screw (41), and the bottom of the power screw (41) is threadedly connected to a loading head (42), which is fixedly connected to the top of the model groove section (14).

4. The model test device for stratum excavation and grouting reinforcement according to claim 3, characterized in that: The servo motor (4) and the power lead screw (41) are connected through a continuously variable transmission and a turbine reducer.

5. The model test device for stratum excavation and grouting reinforcement according to claim 1, characterized in that: The Particle Image Velocity (PIV) system includes a high-definition motion camera (5), which monitors the front, right, and top surfaces of the model box (1); the soil pressure gauge and its associated acquisition device are installed in the sand layer (3).

6. The model test device for stratum excavation and grouting reinforcement according to claim 1, characterized in that: The front and right facades of the model box (1) are made of transparent plexiglass panels (6), while the remaining facades and bottom are made of steel plates. The sidewalls of the model groove section (14) are in close contact with the end of the model box (1) and the transparent plexiglass panels (6).

7. A model test method for stratum excavation and grouting reinforcement, characterized in that: The method uses the model test apparatus for stratum excavation and grouting reinforcement as described in any one of claims 1 to 6, and further includes the following steps: S1. The servo motor (4) drives the power screw (41) to press down the hollow model groove section (14) and expose the sand layer (3) free surface step by step. S2. Use an air compressor (9) to pressurize the water tank (11) so that fresh mud continuously overflows from the model trench section (14) to the excavated free face. The mud overflowing from the trench section comes into contact with the surface of the sand layer (3). S3. Open the pneumatic valve (7) of the mud tank (8) at the bottom of the model box (1) to drive the mud into the mud tank (8), recover excess mud, and promote mud circulation; S4. Using the integrated particle image velocity measurement (PIV) system, soil and water pressure sensor and supporting acquisition device, the surface settlement and sand layer (3) pore pressure changes are monitored in real time.

8. The model test method for stratum excavation and grouting reinforcement according to claim 7, characterized in that: In step S2, the hollow model trough section (14) is pressed down at a rate of 15 mm / min; in step S4, sodium fluorescein tracer is added to the mud slurry, and the mud movement front is obtained by observing the migration of the tracer.

9. A model test method for stratum excavation and grouting reinforcement according to claim 8, characterized in that: In step S4, the high-definition motion camera (5) monitors the front, right and top surfaces of the model box (1) respectively, and monitors the changes in surface subsidence and sand pore pressure in real time.

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