Loose aquifer grouting simulation test device and simulation method

Abstract

The invention discloses a loose aquifer grouting simulation test device and method, and the device comprises an aquifer simulation body which is of a cylinder structure formed by stacking a plurality of layers of cylinder cavities; a digital information acquisition system is embedded in the aquifer simulation body; and a slurry supply system is communicated with the inner cavity of the aquifer simulation body. The device is used for the grouting simulation experiment of the loose aquifer under multi-field environment coupling. The device can simulate the grouting conditions of broken rocks and sand clay with different proportions under different drainage modes and grouting parameters, and further analyzes the diffusion mechanism and grouting reinforcement mechanism and effect of the grout in the unconsolidated formation.

Description

Technical Field

[0001] The present invention belongs to the technical field of coal mine water inrush and sand burst prevention and control, and in particular to the development of a grouting simulation test method and equipment for loose aquifers, and specifically relates to a loose aquifer grouting simulation test device and a simulation method. Background Art

[0002] Coal mining will cause changes in surrounding rock stress, resulting in the gradual loosening and subsequent destruction of the overlying strata. When the cracks caused by rock destruction gradually develop to the point where they approach or conduct water-bearing sand layers, water inrush and sand burst disasters will occur, endangering coal mine production safety and threatening the lives of miners. Therefore, it is necessary to carry out grouting drainage and reinforcement treatment on the overlying loose layer.

[0003] In grouting treatment projects, the frequently encountered receiving media include pores, cracks, caves, karst pipes, tunnel goafs, etc. Different receiving media control the different seepage gel properties of the slurry and the mechanical strength of the plugging body, which makes the grouting project extremely concealed and the hydrogeological and engineering geological conditions complex, resulting in great difficulties in the design of grouting parameters, the inspection of grouting effects and the research of grouting theory.

[0004] The physical model test method can reproduce the grouting treatment process more comprehensively and realistically, providing a basis for establishing new theories and mathematical models, and is an important means of studying grouting theory.

[0005] By determining some parameters in the grouting project through grouting simulation tests, we can analyze the influence of various factors on the grouting effect. The grouting model test can also more realistically reflect the fluid-solid coupling relationship between slurry and rock (soil). In addition, by analyzing the intuitive test results, we can derive the diffusion law of slurry in the simulated designed stratum. Summary of the invention

[0006] In view of the above analysis, the present invention aims to provide a loose aquifer grouting simulation test device and simulation method, considering the indoor grouting model test research under a saturated water environment, which can simulate the grouting conditions of the loose layer under certain hydrodynamic conditions, different clay contents, drainage methods, and grouting parameters, deeply explore the diffusion behavior of the slurry in the loose formation, and evaluate its reinforcement effect, so as to improve the shortcomings of the existing technology.

[0007] The object of the present invention is achieved in that:

[0008] A loose aquifer grouting simulation test device is provided, which is provided with: an aquifer simulation body, which is a cylindrical structure formed by stacking multiple cylindrical cavities; a digital information acquisition system is buried in the aquifer simulation body; and a slurry supply system is connected to the inner cavity of the aquifer simulation body.

[0009] Optionally, the slurry supply system is grouting any layer of the aquifer simulation body, and the digital information acquisition system is arranged around the grouting site.

[0010] Optionally, the digital information acquisition system is provided with an electrically connected data acquisition instrument and a sensor assembly; the sensor assembly is arranged according to the number of layers of the aquifer simulation body, and includes an earth pressure sensor and a pore water pressure sensor.

[0011] Optionally, the soil pressure sensor and the pore water pressure sensor are arranged in a straight line and crosswise with each other.

[0012] Optionally, the soil pressure sensors and pore water pressure sensors are arranged in four directions of the cross section of each layer of the cylindrical cavity.

[0013] Optionally, the aquifer simulation body includes a first simulation layer and a second simulation layer arranged in sequence from top to bottom; a top cover is arranged on the top of the first simulation layer, and a base is arranged on the bottom of the second simulation layer; the simulation layer is formed by two semi-ring structures spliced ​​together.

[0014] Optionally, the aquifer simulation body is provided with a first simulation layer and a second simulation layer, and a plurality of simulation layers are stacked between the first simulation layer and the second simulation layer;

[0015] The first simulation layer is a cylindrical structure formed by splicing two butted arc modules, with a top cover on top;

[0016] The second simulation layer is formed by splicing two butted arc modules into a cylindrical structure, with a base at the bottom;

[0017] Each simulation layer is composed of two butted arc modules spliced ​​together to form a cylindrical structure;

[0018] Water supply and drainage holes are arranged on the arc-shaped module wall.

[0019] Optionally, the slurry supply system is provided with an air compressor, a sealed slurry storage tank and a grouting pipeline which are connected in sequence; the grouting pipeline is connected to the side wall of the aquifer simulation body.

[0020] Optionally, an air inlet valve is provided on the connecting pipeline between the air compressor and the sealed slurry storage tank; an exhaust valve and a pressure gauge are provided on the top of the sealed slurry storage tank, and an agitator is provided therein; a grouting valve is provided at the connection between the grouting pipeline and the sealed slurry storage tank, and a slurry supply flow meter, a pressure relief valve and a grouting pressure sensor are provided at intervals on the subsequent pipeline; a flow meter is provided in connection with the slurry supply flow meter, and a paperless recorder is provided in connection with the grouting pressure sensor.

[0021] A loose aquifer grouting simulation test method is performed using any of the loose aquifer grouting simulation test devices described in the present invention, specifically comprising:

[0022] Step 1: Expel the air from the pore water pressure sensor, connect the data acquisition instrument, and perform troubleshooting, balancing, and zeroing operations on each channel;

[0023] Step 2: Gravel or loose layer medium is filled inside the water-bearing simulation body. After a certain thickness of medium is filled, it is compacted and leveled and water is added to saturate it. After standing, the water surface just reaches the surface of the medium, which is saturated. The volume of water required to saturate the medium after filling is calculated, and the porosity of the configured loose layer medium is calculated from the volume of water added;

[0024] Step 3: During the filling process, bury the pore water pressure sensor, soil pressure sensor and grouting tube in the designed layer, and ensure that all sensor data lines pass through the sensor outlet holes reserved in the top cover;

[0025] Step 4: Cover the top cover and let it stand for a while. After the pressure of the pore water pressure sensor is stable, connect the grouting pipeline.

[0026] Step 5: Under the set grouting pressure conditions, the slurry in the sealed slurry storage tank is injected into the aquifer simulation body through the grouting pipeline, and the slurry displaces the water in the pores of the loose layer medium and collects it through the water supply and drainage holes. When the pore water pressure sensor changes steadily, the grouting is stopped;

[0027] Step 6: Real-time acquisition of dynamic changes in grouting pressure and slurry flow rate during the grouting process, and drawing of the PQt curve to determine the grouting state of the loose layer medium; continuous monitoring of the pore water pressure and soil pressure during the grouting process to obtain the time-varying laws of the pore water pressure and soil pressure;

[0028] Step 7: After the grouting is completed, let it stand until the slurry is initially solidified, observe the slurry diffusion, and dig out the solidified body to measure its diffusion radius; after the final solidification, conduct compressive strength, permeability and triaxial compressive strength tests on the solidified body;

[0029] Step 8: Repeat steps 1 to 7, changing the clay content of the loose layer medium each time, to obtain the diffusion of the slurry and the grouting reinforcement effect under different clay contents.

[0030] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0031] a) The indoor grouting model test takes into account the influence of loose layer clay content, drainage method, ground stress and hydrodynamic conditions on slurry diffusion and grouting effect, ensuring that the test conditions can be adjusted according to the on-site environment.

[0032] b) The changes of physical parameters inside the loose layer during the grouting process are collected in real time. Through multiple groups of orthogonal experiments, the diffusion mechanism of the slurry under the coupling of different clay contents, different grouting pressures, and different drainage methods is revealed. The weight of each influencing factor can be obtained and its constitutive relationship can be constructed.

[0033] c) By comparing the uniaxial compressive strength, triaxial compressive strength and permeability coefficient of the grouting consolidation body under triaxial compressive environment after each group of tests, the rationality of the selection of grouting parameters and drainage methods and the comprehensive grouting effect can be quantitatively evaluated, thereby providing better guidance for on-site construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings:

[0035] Figure 1 A schematic diagram of the structure of the loose aquifer grouting simulation test device provided by the present invention;

[0036] Figure 2 for Figure 1 Schematic diagram of the aquifer simulation structure in FIG.

[0037] Figure 3 for Figure 2 The structural disassembly screenshots are as follows: Figure a is the top cover structure diagram, Figure b is the base structure diagram, and Figure c is the simulation layer structure diagram;

[0038] Figure 4 It is a schematic diagram of the structure of the slurry supply system of the present invention;

[0039] Figure 5 Layout schematic for the sensor;

[0040] Figure 6 Curve of soil pressure changing with time;

[0041] Figure 7 Curve of soil pressure variation with time at measuring point 201;

[0042] Figure 8 Curve of soil pressure variation with time at measuring point 204;

[0043] Fig. 9 Pore ​​water pressure versus time curve;

[0044] Fig.10 Summary of pore water pressure versus time curves;

[0045] in:

[0046] 1-aquifer simulation body, 11-first simulation layer, 12-second simulation layer, 13-top cover, 14-sensor outlet, 15-base, 16-sealing ring, 17-sealing pad, 18-water supply and drainage hole;

[0047] 2-digital information acquisition system, 21-sensor assembly, 211-soil pressure sensor, 212-pore water pressure sensor, 22-data acquisition instrument;

[0048] 3-slurry supply system, 31-air compressor, 311-air inlet valve, 32-sealed slurry storage tank, 321-agitator, 322-exhaust valve, 323-pressure gauge, 33-grouting pipeline, 331-grouting flower pipe, 332-grouting valve, 333-slurry supply flow meter, 334-flow measuring instrument, 335-pressure relief valve, 336-grouting pressure sensor, 337-paperless recorder. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described in detail below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0050] The loose aquifer grouting simulation test device of the present invention is provided with: an aquifer simulation body 1, which is a cylindrical structure formed by stacking multiple cylindrical cavities; a digital information acquisition system 2 is buried in the aquifer simulation body 1; and a slurry supply system 3 is arranged in communication with the inner cavity of the aquifer simulation body 1. Specifically, the slurry supply system 3 is grouted by any layer of the aquifer simulation body 1, and the digital information acquisition system 2 is arranged around the grouting site of the slurry supply system 3. In this embodiment, the slurry supply system 3 is connected to the aquifer simulation body 1 through a grouting pipe interface, and the grouting pipe interface is a two-way quick-plug interface. The sealed slurry storage tank 32 is connected to the water supply and drainage hole 18 on the arc module through an external grouting pipeline 33, and one end of the internal grouting pipe is connected to the grouting pipe interface and the other end is connected to the grouting flower pipe 331. The digital information acquisition system 2 is used to collect information fed back by the pore water pressure sensor 212, the soil pressure sensor 211, the grouting pressure sensor 336 and the slurry supply flow meter 333 during the slurry diffusion process. Through this system, the experimenter can visually observe the dynamic process of slurry diffusion and use these data to optimize the grouting process. The slurry supply system 3 is connected to the aquifer simulation body 1 and is used to transport slurry into the aquifer simulation body 1 so that it diffuses in the sand and soil body to displace the water in the pores and split the sand and soil body to form a slurry skeleton to play a reinforcement role; Figure 1-4As shown, a specific embodiment of the present invention discloses a loose aquifer grouting simulation test device, comprising: a first simulation layer 11 and a second simulation layer 12 arranged in sequence from top to bottom; each simulation layer is formed by butting and splicing two arc modules, and its cross section is a semicircle, and the two arc modules can be spliced ​​into a cylindrical structure as shown in FIG. Figure 4 As shown, it is connected by high-strength bolts, and a rectangular sealing gasket 17 is placed at the connection; the cylindrical structure can be stacked in the vertical direction as needed, and an "O"-shaped sealing ring 16 is placed at the connection. Figure 2 As shown, the arc module is provided with water supply and drainage holes 18. The orientation and number of the drainage holes can be selected according to actual conditions to control the drainage method, and a hose is connected to collect the discharged pore water; the unused drainage holes are blocked with water blocking bolts.

[0051] The digital information acquisition system 2 is provided with an electrically connected data acquisition instrument 22 and a sensor assembly 21; the sensor assembly (21) is arranged according to the number of layers of the aquifer simulation body, and includes a soil pressure sensor 211 and a pore water pressure sensor 212. The soil pressure sensor 211 and the pore water pressure sensor 212 are arranged in a straight line and cross-arranged relative to each other. Preferably, the soil pressure sensor 211 and the pore water pressure sensor 212 are arranged in four directions of the cross section of each layer of the cylindrical cavity. The digital information acquisition system is used to collect information fed back by the pore water pressure sensor 212, the soil pressure sensor 211, the grouting pressure sensor 336 and the slurry supply flowmeter 333 during the slurry diffusion process, so as to realize the visualization of the changes in the pore water pressure, soil pressure, and grouting pressure and flow. In this embodiment, the dynamic data collection of the pore water pressure sensor 212 and the soil pressure sensor 211 is realized by the TST3826F-L dynamic and static strain test analysis system and supporting software; the data fed back by the slurry supply flow meter 333 is collected by the F2001X-A3-I1-C4-R2-PWA-L1-VAC multi-function flow integrator; the data fed back by the grouting pressure sensor 336 is collected by the SIN-R6000C series color paperless recorder.

[0052] The aquifer simulation body 1 includes a first simulation layer 11 and a second simulation layer 12 arranged in sequence from top to bottom; a top cover 13 is arranged on the top of the first simulation layer 11, and a base 15 is arranged on the bottom of the second simulation layer 12. The simulation layer is formed by two semi-ring structures. Figure 3As shown, the top cover 13 and the base 15 are made of steel plates of a certain thickness, and the sensor outlet 14 is set in the center of the flange top cover; a groove with the same diameter as the cylindrical structure is opened in the center of the base for placing the "O"-shaped sealing ring 16. This embodiment uses two cylindrical structures stacked and arranged vertically, and the modules are tightly fitted. The clay-containing sand layer is used inside and a pore water pressure sensor 212 and a soil pressure sensor 211 are arranged therein; the pore water pressure sensor 212 adopts a micro pore water pressure sensor with a range of 100kPa, and the soil pressure sensor adopts a DMTY type soil pressure sensor with a range of 200kPa. The arc module can be combined into cylindrical structures of different sizes and proportions, which are arranged vertically, and the height of the cylindrical structure can be adjusted according to a similar proportion to the actual situation; the gravel layer or a loose layer of a certain ratio is used inside and a pore water pressure sensor 212 and a soil pressure sensor 211 are arranged therein, and a water supply and drainage hole 18 is provided on the shell, and the drainage method can be selected according to the actual situation to achieve control of the slurry diffusion direction; as shown Figure 2 As shown, in this embodiment, the arc module is assembled and welded by 5mm thick Q235 steel, and the two arc modules are spliced ​​into a cylindrical steel cylinder with an inner diameter of 500mm and a height of 250mm. The rectangular sealing gasket 17 and the "O"-shaped sealing ring 16 are made of fluororubber material, wherein the inner diameter of the "O"-shaped sealing ring 16 is 500mm.

[0053] A feasible solution is that the aquifer simulation body 1 is provided with a first simulation layer 11 and a second simulation layer 12, and a plurality of simulation layers are stacked between the first simulation layer 11 and the second simulation layer 12; the first simulation layer 11 is formed by two butted arc modules spliced ​​together to form a cylindrical structure, and a top cover 13 is provided on the top; the second simulation layer 12 is formed by two butted arc modules spliced ​​together to form a cylindrical structure, and a base 15 is provided on the bottom; each simulation layer is formed by two butted arc modules spliced ​​together to form a cylindrical structure; water supply and drainage holes 18 are provided on the wall of the arc module. The arc modules can be spliced ​​together into a cylindrical structure, which is vertically arranged, and the modules are tightly fitted, and are used to fill various granular materials such as gravel layers or sand bodies and arrange pore water pressure and soil pressure sensors; the shell is provided with water supply and drainage holes 18, and the drainage method can be selected according to the actual situation to achieve the change of the hydrodynamic conditions inside the injected medium, thereby controlling the diffusion direction of the slurry. The orientation and number of the water supply and drainage holes 18 can be selected according to the actual situation, and a hose can be connected to collect the discharged pore water. The unused drainage holes are blocked with water plugging bolts. The cross section of the cylindrical steel cylinder is provided with pore water pressure sensors 212 and soil pressure sensors 211 in four directions. There are multiple pore water pressure sensors 212 and soil pressure sensors 211, and they are buried in the clay sand layer or other granular materials when they are filled. Multiple pore water pressure sensors and soil pressure sensors are spaced apart in the vertical direction. Figure 3As shown, in this embodiment, the diameter of the water supply and drainage holes is 8 mm; each arc module is provided with two rows of water supply and drainage holes 18, the lower row of water supply and drainage holes 18 are 60 mm away from the bottom surface, and the upper row of water supply and drainage holes 18 are 60 mm away from the top surface, with four holes in each row and the same spacing; when in use, a drain pipe interface with a valve is installed in the drain hole, and a hose is connected to collect the discharged water.

[0054] The slurry supply system 3 includes an air compressor 31, which is connected to a sealed slurry storage tank 32; an anti-condensation agitator 321 is provided inside the sealed slurry storage tank 32 to prevent the slurry from condensing in the tank; the sealed slurry storage tank 32 is connected to the water supply and drainage holes 18 on the outer wall of the arc structure through a grouting pipeline 33; specifically, the slurry supply system 3 is provided with an air compressor 31, a sealed slurry storage tank 32 and a grouting pipeline 33 which are connected in sequence; the grouting pipeline 33 is connected to the side wall of the aquifer simulation body 1. An air inlet valve 311 is arranged on the connecting pipeline between the air compressor 31 and the sealed slurry storage tank 32; an exhaust valve 322 and a pressure gauge 323 are arranged on the top of the sealed slurry storage tank 32, and an agitator 321 is arranged therein; a grouting valve 332 is arranged at the connection between the grouting pipeline 33 and the sealed slurry storage tank 32, and a slurry supply flow meter 333, a pressure relief valve 335 and a grouting pressure sensor 336 are arranged at intervals on the subsequent pipeline; a flow meter 334 is arranged in connection with the slurry supply flow meter 333, and a paperless recorder 337 is arranged in connection with the grouting pressure sensor 336.

[0055] The loose aquifer grouting simulation test method of the present invention is carried out using the loose aquifer grouting simulation test device of the present invention, and specifically comprises:

[0056] Step 1: Expel the air from the pore water pressure sensor 212, connect the data acquisition instrument 22, and perform troubleshooting, balancing, and zeroing operations on each channel;

[0057] Step 2: Fill the cylindrical structure with a certain proportion of loose layer medium or other granular materials. After each filling of a certain thickness of medium, compact and level it and add water to saturate it. After standing still, the water surface just reaches the surface of the medium, which is saturated. Count the volume of water required to saturate the medium after filling, and calculate the porosity of the configured loose layer medium from the volume of water added;

[0058] Step 3: During the filling process, bury the pore water pressure sensor 212, the soil pressure sensor 211 and the grouting flower tube 331 in the designed layer. Pay attention to the wiring when burying, try to keep the wires away from the location of the grouting flower tube 331, and ensure that all sensor data lines finally pass through the sensor outlet 14 reserved in the top cover 13;

[0059] Step 4: Cover the top cover 13, tighten the high-strength bolts, wait for the pore water pressure to stabilize, and then connect the grouting pipeline;

[0060] Step 5: Under the set grouting pressure condition, the slurry in the sealed slurry storage tank 32 is grouted into the cylindrical structure through the grouting pipeline 33, and the slurry displaces the water in the pores of the loose layer medium, and the water is collected by connecting the hose through the drainage hole 7. When the pore water pressure changes steadily, the grouting is stopped;

[0061] Step 6: Real-time acquisition of dynamic changes in grouting pressure and slurry flow rate during the grouting process, and drawing of the PQt curve to determine the grouting state of the loose layer medium; continuous monitoring of the pore water pressure and soil pressure during the grouting process to obtain the time-varying laws of the pore water pressure and soil pressure;

[0062] Step 7: After the grouting is completed, the slurry is allowed to stand until it is initially solidified, and then the half arc-shaped shell 1 is removed to observe the diffusion distance and direction of the slurry, and the solidified body is dug out to measure its diffusion radius; after final solidification, the compressive strength, permeability and triaxial compressive strength tests are performed on the solidified body;

[0063] Step 8: Repeat steps 1 to 7, changing the clay content of the loose layer medium each time, to obtain the diffusion of the slurry and the grouting reinforcement effect under different clay contents.

[0064] In step 1, the air in the pore water pressure sensor 212 needs to be exhausted in advance by immersing it in 200 mm deep water for 6 hours and shaking it once every hour.

[0065] In step 2, the filling material inside the cylindrical structure is a clay-containing sand layer, which is prepared in a certain proportion and compacted and leveled according to the density sampled on site.

[0066] In this embodiment, the mass required for each 50mm filling is calculated based on the on-site sampling density, and a fixed mass of material is poured in each time and compacted and leveled. The compaction standard is that the fixed mass of material is filled in for the first time and compacted to 50mm, the second filling is compacted to 100mm, and so on, each time 50mm of material is filled until the cylindrical steel cylinder is full.

[0067] In this embodiment, when saturating with water, first use the water plugging bolt to plug the unused water supply and drainage holes, insert the drainage hose into the drainage hole 18 with the drainage pipe interface with a valve, and close the valve on the drainage pipe interface to make it in a non-draining state; place an iron sheet on the surface of the compacted and leveled material, and add water with a beaker with a scale. Saturation is achieved when the water surface just covers the surface of the material. Record the amount of water added every time 50mm of saturation is completed.

[0068] In step three, when the filling material reaches 150mm, 250mm, and 350mm respectively, two pore water pressure sensors 212 and two soil pressure sensors 211 are buried. The line between the two pore water pressure sensors 212 and the line between the two soil pressure sensors 211 form a 90° angle; the distance between each sensor and the center of its cross section is 100mm.

[0069] In step 4, first pass the wires of each sensor through the "O"-shaped sealing ring 16 and then through the sensor wire outlet 14 in the center of the top cover, and then cover the top cover and tighten the screws.

[0070] In step five, first turn on the air compressor 31 to make the air pressure in the tank reach the rated value, and ensure that the exhaust valve 322 and the grouting valve are in the closed state; open the air inlet valve 311 to pressurize the sealed slurry storage tank 32, observe the pressure gauge 323, and when the pressure in the sealed slurry storage tank 32 reaches the set grouting pressure, open the grouting valve 332 to start grouting. During the grouting process, adjust the air inlet valve 311 to stabilize the air pressure in the sealed slurry storage tank 32 at around the set grouting pressure.

[0071] In this embodiment, the grouting pressures are set to 0.2MPa, 0.4MPa, and 0.6MPa, respectively, and the changes in the pore water pressure and soil pressure data are observed after the grouting begins. It is observed that the pore water pressure changes rapidly at the beginning of grouting, with an obvious increase and then an obvious decrease, and then a steady rise, followed by multiple ups and down fluctuations, and finally tends to be stable, at which time the grouting is stopped.

[0072] When grouting is stopped, close the air inlet valve 311 and slowly open the exhaust valve 322 to release air; when the pressure gauge value drops to 0, close the grouting valve 332, open the pressure relief valve to release the pressure in the pipeline, and finally clean the pipeline with clean water.

[0073] In step six, the curves of pore water pressure and soil pressure changing with time at different positions in the same group of tests are integrated to obtain the changes in soil pressure and pore water pressure at different positions in the grouting medium during the grouting process; the curves of pore water pressure and soil pressure changing with time at the same position in different groups are integrated to obtain the changing rules of pore water pressure and soil pressure due to grouting parameters, clay content, and drainage method.

[0074] In step seven, after the slurry has initially set, remove half of the arc-shaped shell and use a shovel to dig in the vertical direction until the slurry veins and bubbles are seen, and measure the slurry vein width, length and grouting diffusion radius; after the slurry has finally set, process the grouting consolidated body into a standard specimen and analyze its physical and mechanical properties in the laboratory.

[0075] In this embodiment, the P.O42.5 cement slurry with a water-cement ratio of 1.0, an initial setting time of 15 hours, and a final setting time of 24 hours are used. A pressure testing machine is used to carry out a uniaxial compressive test, and a Rock Top multi-field coupling tester is used to carry out a permeability test and a triaxial compression failure test under three-way pressure conditions on the processed standard specimens.

[0076] In this embodiment, the selected variables include: clay content 0%, 10%, 20%, 30%, 45%; grouting pressure 0.2MPa, 0.4MPa, 0.6MPa; two drainage methods: drainage on both sides and drainage on all sides. A total of eight groups of orthogonal experiments were conducted.

[0077] The experimental device of the present invention can achieve the following effects:

[0078] (1) A laboratory simulation test system for soil compaction grouting and splitting grouting was designed, which can simulate the pressure grouting process of various media and form complete specimens. The natural generation and development of compaction grout bubbles and splitting cracks in sand and clay were realized through the experiment.

[0079] (2) Splitting grouting in clay-containing sand layers can be divided into three stages: bubbling and compaction stage, first splitting surface stage, and subsequent splitting surface stage. At the beginning of grouting, the grouting pressure is small and cannot split the soil. The soil is relatively loose, and the slurry squeezes the surrounding soil at the grouting pipe mouth to form an ellipsoidal slurry bubble. As the grouting pressure continues to increase, the slurry bubble continues to grow until the grouting pressure is greater than the splitting pressure, and the soil begins to crack along the weakest surface. In uniform soil, the splitting surface will occur on the plane with the least resistance, that is, the plane perpendicular to the minor principal stress. This splitting surface may be any plane passing through the center of the slurry bubble. After the first splitting surface is generated, the slurry is injected into the first splitting surface and squeezes the surrounding soil, causing the soil around the first splitting surface to be continuously compressed and the strength to increase. As the pressure continues to increase, splitting will occur again on the plane with the least resistance. Generally, the second splitting surface will be perpendicular to the first splitting surface. As the grouting proceeds, subsequent splitting surfaces will continue to be generated at the weak surfaces in the soil, eventually forming criss-crossing grout veins.

[0080] (3) With the increase of clay content, the compressibility of sand increases, the radius of slurry bubbles increases, the width of the splitting channel increases, and the extension length of the slurry vein shortens.

[0081] (4) The slurry veins produced by the slurry splitting the sandy soil are wider and extend farther. Within a certain range (generally less than the soil splitting pressure), the radius of the slurry bubble increases with the increase of the grouting pressure. However, when the grouting pressure is much greater than the splitting pressure, the slurry quickly splits the soil to produce a dominant diffusion channel, and the slurry diffuses along the splitting surface, which leads to the appearance of smaller slurry bubbles.

[0082] (5) After draining water through drainage holes in a predetermined direction, the pore water pressure in the sand layer can be reduced, thereby forming a greater pressure difference in the sand body between the grouting hole and the drainage hole, inducing the slurry to diffuse in this direction.

[0083] The following is a verification of the experimental device and experimental method through specific embodiments, which specifically include:

[0084] Embodiment 1:

[0085] The test model designed this time is based on the engineering geological prototype of Zouzhuang Coal Mine, and is obtained by scaling according to a certain similarity ratio. Similar model tests have the characteristics of obvious test phenomena, short cycle, high repetition rate and low cost. Under the condition that the design model is close to the actual stratum structure on site, with the help of accurate monitoring methods and equipment, the model test can more truly reflect the construction phenomena in the actual project, and various monitoring parameters can be obtained intuitively. In the process of model test design, the similarity parameters and conditions between the model and the prototype are usually determined based on the similarity between the proposed design model test and the engineering geological prototype, combined with the requirements of the test equipment in the laboratory. This is the key to ensure the similarity between the engineering geological prototype and the test model, and it is also the key factor for the control of test parameters and the accuracy of data analysis. The properties of weak and loose strata are completely different from those of rock strata. For rock strata, rocks have certain elasticity. When studying their mechanical properties, it is necessary to study from the elastic stage to the plastic stage. Compared with weak and loose strata, its soil layer is basically in the plastic stage, so the stress and displacement of any unit in its stratum are related to the following parameters: cohesion c; internal friction angle φ; bulk density γ; geometric size L. Therefore, when simulating these soft and loose strata, the material strength of the model is very low and the particles are very small. As long as the c and φ values ​​of the model are similar to those of the prototype, the similarity between the model and the prototype can be guaranteed.

[0086] 1 Principle and composition of simulation test system

[0087] 1.1 Design principles of test equipment

[0088] (1) The size of the model must meet the maximum distance of slurry diffusion under the experimental conditions such as grouting pressure and grouting volume;

[0089] (2) The test box should be well sealed to ensure that there will be no water leakage or grout leakage before and after grouting;

[0090] (3) The test system is resistant to high pressure, and its pressure resistance is not less than 1MPa;

[0091] (4) It is convenient for disassembly and assembly, and for observing the diffusion of the stone after grouting;

[0092] (5) The model can be reused for multiple experiments.

[0093] 1.2 Principle of simulation test

[0094] The principle of sand layer grouting simulation test is as follows Figure 1 As shown, the model box provides reaction support for the injected medium. The internal space of the model has a diameter of 0.5m and a height of 0.5m. Since the arc plates of the spliced ​​model box are connected by high-strength bolts, the deformation in all directions is greatly limited, and the soil pressure in the medium will continue to increase with the injection of slurry. In addition, different injected media will have different compaction and splitting conditions, resulting in differences in the change curve and peak value of soil pressure. Water holes are evenly distributed around the box, and the water output can be collected and measured for observing the simulated grouting drainage process. Soil pressure sensors and piezometers are arranged in the sand layer to monitor the stress field and pore water pressure changes near the slurry veins and bubbles and other areas during the slurry diffusion process.

[0095] 1.3 Model test chamber

[0096] The model test frame is used as the sand and soil bearing, sensor layout space and grouting operation platform in the test. Figure 1-4 As shown, the interior of the test frame is a rectangular space with a diameter of 0.5m and a height of 0.5m. The test frame is assembled from four arc-shaped steel plates, and the contact position of the steel plates is connected with high-strength bolts. The thickness of the steel plates is 1cm. The top and bottom plates are connected with high-strength bolts to simulate the upper stratum pressure state where the "four containments" are located. Three water outlets are evenly distributed on the side of the test box, and a high-pressure hose interface is installed to connect the hose to facilitate water collection. A 20mm round hole is left on the top cover of the test box as the lead-out hole for the sensor data line. The grouting hole is located in the upper half of the side of the test box, and an 8mm high-pressure hose connector is installed. The grouting pump is directly connected to the outside, and the high-pressure hose is connected to the inside and arranged vertically at the grouting position. Rubber sealing rings are installed at the connection between the two arc plates and the connection between the upper and lower parts of the box to play a waterproof and sealing role.

[0097] The dynamic monitoring system includes an internal monitoring system and an external monitoring system. The internal monitoring system is used to monitor the stress field and pore water pressure inside the sand layer; the external monitoring system is used to collect grouting pressure data in real time during the grouting process.

[0098] (1) Internal monitoring system

[0099] The stress field is monitored by using a DMTY soil pressure box, TST3826F-L dynamic and static strain test analysis system and supporting software. The soil pressure box has a diameter of 28mm and a range of 200kPa. During the grouting process, the stress field changes near the slurry vein and other areas can be monitored; after the grouting is completed, the ground stress dissipation can be monitored. The pore water pressure is monitored by a micro pore water pressure gauge with a range of 100kPa.

[0100] (2) Grouting pressure monitoring

[0101] The grouting pressure during the grouting process is monitored by installing a digital pressure sensor on the grouting pipeline.

[0102] 1.4 Grouting control system

[0103] The grouting control system consists of a BT100 peristaltic constant flow pump, a YZ2515 pump head, a high-pressure slurry delivery pipeline, a stirrer and a slurry storage tank. The grouting material is ordinary cement slurry, which is injected through the grouting hole on the side of the model box. After the grouting is completed, the grouting pump is turned off and the pipeline is depressurized and cleaned.

[0104] 2 Experimental Materials and Methods

[0105] 2.1 Test materials

[0106] (1) Injected medium

[0107] The injected medium is medium-fine sand containing clay from Huaibei area. The sand sample has good gradation, and its indexes are shown in Table 1.

[0108] Table 1 Experimental sand sample gradation distribution table

[0109] Control particle size Effective particle size Characteristic particle size Unevenness coefficient Curvature coefficient 1.55 0.04 0.45 40.7 2.69

[0110] (2) Grouting materials

[0111] P.042.5 cement is selected as the grouting material. The basic properties of pure cement slurry under different water-cement ratios are shown in Table 2. After comparing the grouting effects of a large number of experiments, the water-cement ratio of the slurry selected in this experiment is 1.0.

[0112] Table 2 Performance parameters of cement slurry with different water-cement ratios

[0113]

[0114] 2.2 Test methods

[0115] The sand used for the test filling material is medium-fine sand. In order to control the physical indicators to be consistent with the actual stratum conditions during the filling process, the layered filling method is adopted to control the density of the filling by controlling the dry density of the filling. The initial dry density of the filling in the test is 1.9g / cm 3 , compacted every 5cm. The grouting pipe is made of high-pressure hose, and the grouting position is 25cm away from the bottom of the model box. Since the grouting effect of the flower pipe was not good in the previous experiment, the high-pressure hose direct grouting method was adopted. During the test, the grouting rate was controlled to be constant, and the grouting volume was controlled to 2L.

[0116] 2.3 Sensor Arrangement

[0117] The sensors are arranged in three layers in the model box. Sensors numbered 201, 202, 203, 204, 205, and 206 are soil pressure sensors, of which sensors 203 and 204 monitor horizontal soil pressure, and the others monitor longitudinal soil pressure. Sensors numbered A15384, A15303, and A12505 are piezometers that monitor pore water pressure. The main goal of stress field monitoring is to obtain changes in soil pressure in the area near the slurry vein along the slurry diffusion path. In addition, the vertical stress sensor and the lateral stress sensor are basically arranged symmetrically to monitor changes in horizontal and vertical ground stress. See the arrangement of the sensor positions for details. Figure 5 .

[0118] 2.4 Experimental plan

[0119] The main problem to be solved in this experiment is to establish a split grouting model in a gravel layer, study the diffusion law and morphology of the slurry under different sand-to-clay ratios, and adopt a research method that combines traditional indoor models with field practice and theoretical research with actual engineering. Combined with relevant literature and field test experience, 6 groups of tests are planned to be carried out, and the designed experimental plan is shown in Table 3.

[0120] Table 3 Simulation experiment plan

[0121]

[0122] 3 Experimental implementation steps

[0123] (1) Test frame assembly and filling: Fill the sand according to the physical indicators of the test design, and assemble the test frame as needed as the filling process proceeds.

[0124] (2) Add fine sand into the model test box, using wooden sleepers and tamping as you add it. During the tamping process, use a leveler to tamp and level every 5 cm of sand, add water to saturate it, and then continue to add the injected medium.

[0125] (3) Sensor installation and system debugging: According to the monitoring plan, soil pressure sensors and piezometers are buried at the 150 mm, 250 mm, and 350 mm layers respectively, and the monitoring system is debugged.

[0126] (4) A high-pressure grouting hose is buried vertically at a depth of 250 mm, and the position of the grouting hose is fixed to prevent displacement during subsequent filling compaction.

[0127] (5) Repeat the steps of compacting the filler, paying attention to the wiring during the process, and ensure that all sensor data cables finally pass through the lead holes reserved in the top cover.

[0128] (6) After filling the test box, dig a certain area shallowly at the edge and in the middle of the surface as a water-saturated seepage channel, and compact this part after it is saturated with water.

[0129] (7) Put on the top cover, tighten the high-strength bolts, and let it stand until the pore water pressure stabilizes.

[0130] (8) Connect the grouting pipeline to implement grouting and monitor the changes in various data.

[0131] 4 Analysis of the characteristics of pore water pressure and soil pressure data changes

[0132] 4.1 Analysis of soil pressure changes

[0133] The earth pressure gauge and piezometer are symmetrically arranged on both sides of the grouting pipe, divided into three layers, with a layer spacing of 10 cm. For detailed arrangement, see Figure 5 . The soil pressure gauge and osmometer used in this experiment are miniature resistive soil pressure boxes and osmometers produced by Nanjing Danmo Electronic Technology Co., Ltd. The data changes during the grouting process were detected using the TST3826F-L dynamic and static strain test analysis system and supporting software. Taking the first group of experiments as an example, the materials required for the first group of experiments were prepared according to the designed plan. When the grouting pressure was 0.2MPa and the clay content was 0%, the soil pressure values ​​at each measuring point during the grouting process were summarized to obtain a curve, as shown below: Figure 6 As shown:

[0134] from Figure 6 It can be seen from the figure that, taking the 202 measuring point as an example, the data did not change significantly between 0 and 20 seconds, and the soil pressure was in a stable state. After 20 seconds, as the grouting continued, the soil pressure increased significantly and then decreased significantly. This phenomenon may be due to the continuous development of slurry bubbles and the compaction of the stratum as the grouting progressed, which increased the soil pressure. Then the slurry split the stratum and entered the sand along the splitting channel, and the soil pressure decreased significantly. The first peak value was often greater than the subsequent peak values, so the first splitting was the main splitting. The grouting process was stable between 130 and 400 seconds. During this process, the soil pressure would increase with the suction of the grouting pump and the grouting process. The fluctuation phenomenon under the pressure, combined with other measured values, shows that the pressure values ​​of the measuring points 201 and 202 located below the grouting port are the largest, and the measuring points 205 and 206 located above the grouting hole are slightly affected by the slurry, so the changes are small and the pressure values ​​are small; between 280 and 400 seconds, the soil pressure tends to increase gradually, but because the grouting pressure remains unchanged, the main splitting cannot occur again, but there are continuous small peak points, corresponding to the secondary splitting during the grouting process; when the grouting is stopped at 400 seconds, the soil pressure decreases rapidly, but it is higher than the soil pressure before grouting. Since the positions of the measuring points 205 and 206 are not greatly affected by grouting, the measuring points of the two layers 201 and 204 are selected to compare the six groups of experiments. Figure 7 and Figure 8 The changes in soil pressure at measuring points 201 and 204 are summarized respectively.

[0135] The 201 measuring point monitors the vertical soil pressure. First, the grouting conditions are controlled to be 0.2MPa grouting pressure, drainage around, and the variable is the clay content in the grouting medium. The clay contents selected in the experiment are 0%, 30% and 45% respectively. Figure 7 It can be seen that with the increase of clay content, the rise of soil pressure produces hysteresis. In the experiments with clay content of 30% and 45%, the time required for the soil pressure to rise increased significantly. In addition, the peak value of soil pressure tends to decrease with the increase of clay content. Especially when the clay content is 45%, due to the increase in the plasticity of the sand layer, the soil pressure changes slowly. After reaching the maximum value, it is basically in a state of ups and downs, and there is no obvious decline process. Then the control variables are grouting pressure, clay content of 30%, and drainage on all sides of the model. It can be seen that when other conditions such as clay content and water-cement ratio remain unchanged, the grouting pressure has a significant effect on the change of soil pressure over time. The greater the grouting pressure, the shorter the change time of the soil pressure at the measuring point, the greater the increase, and the greater the final residual soil pressure after the grouting is stopped. Finally, when the clay content is 30% and the grouting pressure is 0.2MPa, the effects of the two drainage methods on the change of soil pressure are compared. From Figure 7 It can be seen that the peak value of soil pressure when drainage is carried out on both sides is smaller than that when drainage is carried out on all sides, and the change amplitude is relatively gentle. This is because the drainage on both sides makes the diffusion trend of the slurry mainly diffuse toward the direction of the line connecting the drainage holes on both sides and diffuse perpendicular to the line as a supplement, which leads to the slow change of soil pressure at the measuring point.

[0136] The transverse soil pressure sensor is set at measuring point 204, which is located at the same layer as the grouting hole. Figure 8 It can be seen that with the increase of clay content, the change amplitude of lateral earth pressure decreases and the time of change is prolonged. When the clay content is 45%, the value of earth pressure changes very little, which shows that between 30% and 45% clay content, the physical and mechanical properties of grouting medium have changed significantly.

[0137] In terms of grouting pressure, the curves of 30%, 0.2MPa (drainage around) and 30%, 0.4MPa (drainage around) show that the greater the grouting pressure, the steeper the curve of soil pressure change over time, indicating that the lateral soil pressure changes faster. The grouting pressure of the 30%, 0.6MPa (drainage around) curve is the largest, but the lateral soil pressure changes very little. Combined with the analysis of the excavated consolidation body, it is concluded that the reason for this phenomenon is that due to the high grouting pressure, the slurry produces a splitting surface at the top of the grouting hole and spreads along the splitting surface, while the slurry bubbles at the layer where the lateral soil pressure sensor is located are less diffused and smaller.

[0138] The drainage pattern is obviously a huge influence on the lateral earth pressure. Figure 8As shown in the two curves of 30%, 0.2MPa (drainage on all sides) and 30%, 0.2MPa (drainage on both sides), both are carried out under the conditions of grouting pressure of 0.2Mpa and clay content of 30%, but the data are obviously different. This is because the drainage method can guide the direction of slurry diffusion, reduce the diffusion distance of the slurry in the direction perpendicular to the line connecting the drainage holes on both sides, and reduce the disturbance to the land at the measuring point.

[0139] 4.2 Analysis of pore water pressure changes

[0140] Taking the test under the conditions of 30% clay content, 0.2MPa grouting pressure and surrounding drainage as an example, the materials required for the test were prepared according to the design plan, and the pressure screw of the grouting pump was adjusted to control the grouting pressure to 0.2MPa. The pore water pressure gauge is divided into two layers, and the pore water pressure gauges taken for analysis are A15384, A15303, and A12505. The pore water pressure change curves at different points over time are summarized in Fig. 9 :

[0141] Depend on Fig. 9 It can be seen that, unlike the soil pressure which has almost no reaction within about 20 seconds after the grouting, the pore water pressure changes rapidly at the beginning of grouting, with a significant increase and then a significant decrease. This phenomenon corresponds to the process of pore water pressure increasing during the osmotic densification of the formation when the grouting starts, and then the slurry splits the formation and enters the sand along the splitting cracks, and the pore water is significantly reduced.

[0142] When the first split cannot continue to extend, the pore water pressure enters a stable rising stage. If no new split occurs afterwards, it enters a stable grouting process. In this process, the pore water pressure will also fluctuate up and down with the grouting pump's grouting and grouting process. Similar to the soil pressure gauge, the water pressure at the measuring point closest to the grouting port is the largest. For example, the A12505 pore water pressure gauge is the closest to the grouting pipe in horizontal distance. When the grouting pressure fluctuates and rises, it can react first and most strongly to the pressure change and is the most sensitive. Similarly, the pore water pressure at the measuring point farthest away is the smallest, see Fig. 9 Middle A15303 curve.

[0143] After grouting is stopped, the grouting pressure becomes zero, and the slurry and pore water in the formation have no power drive, so the curve will drop sharply. The subsequent sensor data curve tends to be smooth and slowly decreases until the data stabilizes. The stable data of each pore water pressure gauge after grouting is greater than the data before grouting (after saturation).

[0144] In order to further analyze the variation of pore water pressure during grouting when changing variables such as grouting pressure, clay content and drainage method, the pore water pressure sensor at the A15384 measuring point was selected, the data was processed and the variation curves in the six groups of experiments were summarized for comparison. The summarized pore water pressure variation curves over time are shown in Fig.10 .

[0145] Comparing the three curves of 0%, 0.2MPa (drainage around), 30%, 0.2MPa (drainage around) and 45%, 0.2MPa (drainage around), it can be seen that with the increase of clay content, the initial value of pore water pressure decreases and the amplitude of change becomes smaller. In the experiment of 45%, 0.2MPa (drainage around), the water pressure rise process slows down obviously, and there is no steep drop in the water pressure value during the grouting process. This is because the slurry does not split during diffusion and always penetrates the compacted sand body. In addition, after the clay content increases, the porosity in the sand body decreases, the permeability decreases, and the slurry is difficult to penetrate into the pore channel, resulting in a decrease in the peak value of the pore water pressure that can be reached during the grouting process; similarly, after the grouting is completed, the drainage rate of the drainage hole decreases, and the rate of decrease of the pore water pressure also slows down.

[0146] From the curves of 30%, 0.2MPa (drainage around), 30%, 0.4MPa (drainage around) and 30%, 0.6MPa (drainage around), it can be seen that the higher the grouting pressure, the faster the pore water pressure rises and the larger the maximum value that can be reached. Overall, for large grouting pressure, after the pore water pressure reaches the first peak, the change gradually tends to be gentle. This is because during the grouting process, once the sand body is split, the pore water will experience a pressure relief process. The smaller the grouting pressure, the longer it takes for the slurry to reach the maximum splitting distance, and the more the pore water pressure at the measuring point is reduced; the higher the grouting pressure, the faster the slurry enters, the released pressure can be replenished in time, and the pressure reduction will become smaller.

[0147] In the 30%, 0.2MPa (drainage on both sides) experiment, the drainage method was changed to drainage on both sides, and the piezometer was located on the line connecting the drainage holes on both sides, and the pore water at its location was in dynamic discharge and replenishment. The pore water pressure value increased slightly, and the increase was slow. The overall curve is much lower than the pore water pressure value in the 30%, 0.2MPa (surrounding drainage) comparison experiment, so a large hydraulic gradient is formed with the grouting hole position, inducing the slurry to diffuse in the direction of the piezometer. It fully shows that by changing the hydraulic gradient in the grouting medium, the purpose of grouting in the predetermined direction can be achieved.

[0148] The specific implementation methods described above further illustrate the purpose, technical solutions and beneficial effects of the present application in detail. It should be understood that the above description is only the specific implementation method of the present application and is not limited to the protection scope of the present application. Any modifications, leg replacements, improvements, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A loose aquifer grouting simulation test device, characterized in that: set up: An aquifer simulation body (1), wherein the aquifer simulation body (1) is a cylindrical structure formed by stacking multiple cylindrical cavities; A digital information acquisition system (2) is buried in the aquifer simulation body (1); A slurry supply system (3) is provided in communication with the inner cavity of the aquifer simulation body (1).

2. The loose aquifer grouting simulation test device according to claim 1 is characterized in that: The slurry supply system (3) is grouting any layer of the aquifer simulation body (1), and the digital information acquisition system (2) is arranged around the grouting site of the slurry supply system (3).

3. The loose aquifer grouting simulation test device according to claim 1 or 2, characterized in that: The digital information acquisition system (2) is provided with an electrically connected data acquisition instrument (22) and a sensor assembly (21); The sensor assembly (21) is arranged according to the number of layers of the aquifer simulation body, and comprises an earth pressure sensor (211) and a pore water pressure sensor (212).

4. The loose aquifer grouting simulation test device according to claim 3 is characterized in that: The soil pressure sensor (211) and the pore water pressure sensor (212) are arranged in a straight line and cross-connected with each other.

5. The loose aquifer grouting simulation test device according to claim 3 is characterized in that: The soil pressure sensor (211) and the pore water pressure sensor (212) are arranged in four directions of the cross section of each cylindrical cavity.

6. The loose aquifer grouting simulation test device according to claim 1 or 2, characterized in that: The aquifer simulation body (1) comprises a first simulation layer (11) and a second simulation layer (12) which are arranged in sequence from top to bottom; A top cover (13) is arranged on the top of the first simulation layer (11), and a base (15) is arranged on the bottom of the second simulation layer (12). The simulation layer is formed by two semi-ring structures.

7. The loose aquifer grouting simulation test device according to claim 5 is characterized in that: The aquifer simulation body (1) is provided with a first simulation layer (11) and a second simulation layer (12), and a plurality of simulation layers are stacked between the first simulation layer (11) and the second simulation layer (12); The first simulation layer (11) is formed by splicing two butted arc-shaped modules into a cylindrical structure, and a top cover (13) is arranged on the top; The second simulation layer (12) is formed by splicing two butted arc-shaped modules into a cylindrical structure, and a base (15) is arranged at the bottom; Each simulation layer is composed of two butted arc modules spliced ​​together to form a cylindrical structure; Water supply and drainage holes (18) are provided on the arc-shaped module wall.

8. The loose aquifer grouting simulation test device according to claim 1 or 2, characterized in that: The slurry supply system (3) is provided with an air compressor (31), a sealed slurry storage tank (32) and a grouting pipeline (33) which are connected in sequence; The grouting pipeline (33) is in communication with the side wall of the aquifer simulation body (1).

9. The loose aquifer grouting simulation test device according to claim 8 is characterized in that: An air inlet valve (311) is arranged on the connecting pipeline between the air compressor (31) and the sealed slurry storage tank (32); An exhaust valve (322) and a pressure gauge (323) are arranged on the top of the sealed slurry storage tank (32), and an agitator (321) is arranged inside the sealed slurry storage tank; A grouting valve (332) is arranged at the connection between the grouting pipeline (33) and the sealed grouting tank (32), and a grouting liquid supply flow meter (333), a pressure relief valve (335) and a grouting pressure sensor (336) are arranged at intervals on the subsequent pipeline; A flow meter (334) is connected to the slurry supply flow meter (333), and a paperless recorder (337) is connected to the grouting pressure sensor (336).

10. A loose aquifer grouting simulation test method, characterized in that: The method is carried out using the loose aquifer grouting simulation test device according to any one of claims 1 to 9, specifically comprising: Step 1: exhaust the air in the pore water pressure sensor (212), connect the data acquisition instrument (22), and perform troubleshooting, balancing and zeroing operations on each channel; Step 2: Gravel or loose layer medium is filled inside the water-containing simulated body (1). After a certain thickness of medium is filled, it is compacted and leveled and water is added to saturate it. After standing, the water surface just reaches the surface of the medium, which is saturated. The volume of water required to saturate the medium after filling is calculated, and the porosity of the configured loose layer medium is calculated from the volume of water added; Step 3: During the filling process, bury the pore water pressure sensor (212), the soil pressure sensor (211) and the grouting flower tube (331) at the designed layer, and ensure that all sensor data lines pass through the sensor outlet (14) reserved on the top cover (13); Step 4: Cover the top cover (13) and let it stand for a while until the pressure of the pore water pressure sensor (212) is stable, and then connect the grouting pipeline (33); Step 5: Under the set grouting pressure conditions, the slurry in the sealed slurry storage tank (32) is injected into the aquifer simulation body (1) through the grouting pipeline (33), and the slurry displaces the water in the pores of the loose layer medium and collects it through the water supply and drainage holes (18). When the change amplitude of the pore water pressure sensor (212) is stable, the grouting is stopped; Step 6: Real-time acquisition of dynamic changes in grouting pressure and slurry flow rate during the grouting process, and drawing of the PQt curve to determine the grouting state of the loose layer medium; continuous monitoring of the pore water pressure and soil pressure during the grouting process to obtain the time-varying laws of the pore water pressure and soil pressure; Step 7: After the grouting is completed, let it stand until the slurry is initially solidified, observe the slurry diffusion, and dig out the solidified body to measure its diffusion radius; after the final solidification, conduct compressive strength, permeability and triaxial compressive strength tests on the solidified body; Step 8: Repeat steps 1 to 7, changing the clay content of the loose layer medium each time, to obtain the diffusion of the slurry and the grouting reinforcement effect under different clay contents.

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