Experimental device for simulating grouting solidification of upper-layer flow plastic soil of karst roof

Abstract

The utility model provides an experimental device for simulating grouting solidification of upper-layer flow plastic soil of a karst roof. The device mainly comprises a simulated karst environment, a grouting system and a data acquisition system. Combination of karst fissures and upper-layer flow plastic soil is simulated in the transparent organic glass device, the flowing and distribution conditions of grout in the fissures and the soil body can be visually observed in an experiment, and real-time data in the grouting process are recorded through the pressure sensor and the flow meter. The device can simulate different grouting pressures, flow rates and slurry materials, and research the influence of different conditions on the curing effect. Experimental results can provide theoretical basis and technical support for grouting reinforcement of the flow plastic soil layer 7 in the karst geological environment.

Description

Technical Field

[0001] The utility model relates to the technical field of geotechnical engineering, in particular to an experimental device for simulating laminar plastic soil grouting and solidification on a karst roof. Background Art

[0002] In karst geology, caves are common in underground projects. This is particularly true during the design and construction of building pile foundations. Caves can prevent pile foundations from reaching their intended bearing capacity, thus impacting project safety and stability. Research into how to solidify fluidized soil through grouting to enhance the bearing capacity of cave roofs and prevent pile foundation failure due to topping has become an important research topic. However, existing technologies are unable to accurately simulate the grouting solidification process and topping failure in karst environments.

[0003] Therefore, it is of great significance to develop an experimental device that can accurately simulate the grouting and solidification process of karst roof plastic soil. Utility Model Content

[0004] The utility model aims to provide an experimental device for simulating laminar flow plastic soil grouting and solidification on a karst roof, so as to solve the problems existing in the prior art.

[0005] The technical solution adopted to achieve the purpose of the utility model is as follows: an experimental device for simulating laminar plastic soil grouting and solidification on a karst roof, including a karst environment simulation system, a grouting system, a data acquisition system, a drainage system and a video monitoring system.

[0006] The karst environment simulation system includes a transparent test chamber, a karst cavity structure, and a pile-topping failure simulation unit. The inner cavity of the transparent test chamber is filled, from bottom to top, with the base bearing layer, the soft rock layer surrounding the cave, a thin roof structure, a fluidized soil layer, and the overlying rock layer. The karst cavity structure is a hollow cubic structure. It has a cavity within it. The karst cavity structure is buried in the soft rock layer surrounding the cave. The upper surface of the karst cavity structure abuts the lower surface of the thin roof structure, and the lower surface rests on the upper surface of the base bearing layer. The pile-topping failure simulation unit includes a steel casing and an iron pipe. The steel casing is a cylindrical structure. The lower end of the steel casing rests on the upper surface of the thin roof structure. The open lower end of the steel casing is blocked by the thin roof structure. The upper end of the steel casing extends beyond the fluidized soil layer and the overlying rock layer. The iron pipe is housed within the inner cavity of the steel casing.

[0007] The grouting port of the grouting system is covered in a fluidized soil layer.

[0008] The data acquisition system includes a computer-controlled monitoring system, an earth pressure gauge, a strain gauge, a flow meter, and a pressure sensor. The earth pressure gauge is embedded in the fluidized soil layer. The elevation of the earth pressure gauge is higher than the elevation of the grouting port. The strain gauge is applied to the upper surface of the thin roof structure. The grouting system is equipped with a flow meter and a pressure sensor. The earth pressure gauge, strain gauge, flow meter, and pressure sensor are all connected to the computer-controlled monitoring system.

[0009] Furthermore, the transparent test box is made of organic glass.

[0010] Furthermore, the karst cavity structure is cast with cement.

[0011] Furthermore, the thin top plate structure is integrally cast with cement.

[0012] Furthermore, the grouting system includes four grouting units. Each grouting unit includes a slurry storage tank, a grouting pump, and a grouting pipe. The grouting pump is connected to the slurry storage tank and the grouting pipe. The grouting ports of the four grouting pipes are arranged around the steel casing.

[0013] Furthermore, the base bearing layer is a hard rock layer with a thickness of 0.1m. The soft rock layer surrounding the cave is 0.4m thick. The thickness of the thin roof structure is 0.08m. The thickness of the fluidized soil layer is 0.22m. The overlying rock layer is a soft rock layer with a thickness of 0.2m.

[0014] The technical effect of the present invention is unquestionable: it overcomes the difficulty of accurate simulation in the existing technology. The transparent acrylic test box and prefabricated cement cavity structure enhance the visibility and operability of the experiment. The grouting system accurately controls the injection volume and pressure of the slurry. Combined with the real-time monitoring of the flow meter and pressure sensor, the accurate collection and analysis of experimental data are achieved. The device can also simulate the phenomenon of pile foundation topping failure, observe the mechanical response of fluidized soil under different grouting conditions, and reveal its dynamic change law. The device provides important experimental data support for pile foundation construction in karst geology and has high engineering application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a front view of the experimental device for simulating laminar flow plastic soil grouting and solidification on the karst roof;

[0016] Figure 2 A top view of the experimental setup for simulating laminar plastic soil grouting and solidification on karst roof;

[0017] FIG3( a ) is a top view of the karst stratum structure, and FIG3( b ) is a front view of the karst stratum structure;

[0018] Figure 4 This is a structural front view of the pile foundation grouting device;

[0019] Figure 5 Schematic diagram of the three-dimensional structure of the experimental device simulating laminar plastic soil grouting and solidification on the karst roof.

[0020] In the figure: iron pipe 1, steel casing 2, base bearing layer 3, soft rock layer around the cave 4, karst cavity structure 5, thin roof structure 6, fluidized soil layer 7, overlying rock layer 8, grouting pipe 9, grouting pump 10, computer control monitoring system 11, slurry storage tank 12, soil pressure gauge 13, strain gauge 14. DETAILED DESCRIPTION

[0021] The present invention will be further described below with reference to the following embodiments. However, it should not be understood that the scope of the present invention is limited to the following embodiments. Without departing from the above technical concept of the present invention, various substitutions and modifications based on common technical knowledge and customary means in the field should be included in the scope of protection of the present invention.

[0022] Example 1:

[0023] This embodiment provides an experimental device for simulating laminar plastic soil grouting and solidification on a karst roof, comprising a karst environment simulation system, a grouting system, and a data acquisition system.

[0024] The karst environment simulation system includes a transparent test chamber, a karst cavity structure 5, and a pile topping failure simulation unit. The interior of the transparent test chamber is filled, from bottom to top, with a base bearing layer 3, a soft rock layer 4 surrounding the cave, a thin roof structure 6, a fluidized soil layer 7, and an overlying rock layer 8. The karst cavity structure 5 is a hollow cubic structure. It contains a cavity. It is buried in the soft rock layer 4 surrounding the cave. The upper surface of the karst cavity structure 5 abuts the lower surface of the thin roof structure 6, and its lower surface rests on the upper surface of the base bearing layer 3. The pile topping failure simulation unit includes a steel casing 2 and an iron pipe 1. The steel casing 2 is a cylindrical structure. The lower end of the steel casing 2 rests on the upper surface of the thin roof structure 6. The open lower end of the steel casing 2 is sealed by the thin roof structure 6. The upper end of the steel casing 2 extends beyond the fluidized soil layer 7 and the overlying rock layer 8. The iron pipe 1 is accommodated in the inner cavity of the steel casing 2. Hammering from the upper part of the iron pipe 1 can penetrate the roof structure.

[0025] The grouting port of the grouting system is covered in the fluidized soil layer 7 .

[0026] The data acquisition system includes a computer-controlled monitoring system 11, an earth pressure gauge 13, a strain gauge 14, a flow meter, and a pressure sensor. The earth pressure gauge 13 is buried in the fluidized soil layer 7. The elevation of the earth pressure gauge 13 is higher than the elevation of the grouting port. The strain gauge 14 is applied to the upper surface of the thin roof structure 6. The grouting system is equipped with a flow meter and a pressure sensor. The earth pressure gauge 13, strain gauge 14, flow meter, and pressure sensor are all connected to the computer-controlled monitoring system 11. The computer-controlled monitoring system 11 is used to control the grouting volume and grouting pressure and monitor changes in earth pressure and roof deformation.

[0027] By simulating the combination of karst fissures and the upper layer of fluidized soil in a transparent plexiglass device, the experiment allowed for the direct observation of the flow and distribution of grouting fluid within the fissures and soil. Real-time data from the grouting process was recorded using pressure sensors, flow meters, and a video monitoring system. This device can simulate different grouting pressures, flow rates, and slurry materials, allowing for the study of how these conditions affect the curing effect. The experimental results provide theoretical support and technical support for grouting reinforcement of the fluidized soil layer in karst geological environments.

[0028] Example 2:

[0029] The main contents of this embodiment are the same as those of embodiment 1, wherein the transparent test box is made of organic glass, the karst cavity structure 5 is cast with cement, and the thin top plate structure 6 is integrally cast with cement.

[0030] Example 3:

[0031] The main contents of this embodiment are the same as those of embodiment 1 or 2, wherein the grouting system includes four groups of grouting units. Each group of grouting units includes a slurry storage tank 12, a grouting pump 10, and a grouting pipe 9. The grouting pump 10 is connected to the slurry storage tank 12 and the grouting pipe 9. The grouting ports of the four grouting pipes 9 are arranged around the steel casing 2. The grouting pump 10 is connected to a computer control monitoring system 11. The computer control monitoring system 11 is used to control the grouting volume and grouting pressure and monitor soil pressure changes and roof deformation.

[0032] Example 4:

[0033] The main contents of this embodiment are the same as those of Examples 1 to 3, except that the base bearing layer 3 is a hard rock layer with a thickness of 0.1m-0.2m. The soft rock layer 4 surrounding the cave is 0.3m-0.4m thick. The thin roof structure 6 is 0.08m-0.1m thick. The fluidized soil layer 7 is 0.22m-0.25m thick. The overlying rock layer 8 is a soft rock layer with a thickness of 0.2m-0.25m.

[0034] Example 5:

[0035] This embodiment provides an experimental method according to any one of the experimental devices described in embodiments 1 to 4, comprising the following steps:

[0036] Step 1: Before conducting the experiment, check the grouting and curing experimental device to ensure that the equipment is placed stably, and at the same time ensure that the components are placed flat and the entire model box is a cube.

[0037] Step 2: According to the experimental requirements, as shown in Figure 3 (a) and (b), cement is used to cast the karst cavity. The cavity is a cube with a side length of 0.4m. The upper part of the cavity is a roof. The cavity needs to be cured for a period of time, and the curing time is 10 days.

[0038] Step 3: Figure 4 As shown, a hard rock layer with a thickness of 0.1m is arranged at the bottom of the karst cavity to simulate the pile foundation entering the rock bearing layer after passing through the cave. The bedrock layer is configured as a high-strength rock material.

[0039] Step 4: Place the cast karst cavity on the hard rock layer, and cast a relatively soft rock layer around it with a thickness of 0.4m to simulate the rock layer environment around the cave.

[0040] Step 5: A thinner roof layer is built on the upper part of the karst cavity layer, which has mechanical properties close to those of the rock layers around the cavity. Strain gauges 14 are laid on the roof layer to ensure that deformation can be monitored when the roof is penetrated.

[0041] Step 6: A steel casing 2 is set up in the center of the upper part of the top plate, and fluidized soil is laid around the steel casing 2. An iron pipe 1 is placed in the middle of the steel casing 2 to simulate the phenomenon of pile topping damage. An earth pressure sensor is laid in the fluidized soil. The sensor is located a certain distance above the grouting port to prevent the grouting from solidifying.

[0042] Step seven: grouting pipes 9 are set up around the upper steel casing 2 of the top plate, and the grouting pipes 9 are inserted into the slurry storage tank 12. The slurry storage tank 12 and the grouting pump 10 constitute the entire grouting device.

[0043] Step 8: The upper part of the fluidized soil layer 7 is a soft rock layer with a thickness of 0.2m. The soft rock wraps the steel casing 2 and the four grouting pipes 9 to prevent leakage from the upper part during grouting.

[0044] Step 9: Prepare grouting materials, including cement, fly ash, sand, stone powder and water, inject them according to a certain grouting pressure, monitor the changes in the flow meter, inject different grouting volumes respectively, and control the grouting speed at 0.5~1L / min.

[0045] Step 10: After the injection is completed and a period of curing is performed, the position of the iron pipe 1 is fixed, and then the upper part of the iron pipe 1 is hammered to observe and monitor the pressure and strain changes. When the iron pipe 1 is completely broken by the top, observe whether the fluidized soil has entered the karst cavity.

[0046] Step 11: After the experiment is finished, the grouting system is turned off, the grouting pipe 9 is cleaned, and the data of the grouting process and the top impact failure process are analyzed.

Claims

1. An experimental device simulating laminar flow plastic soil grouting and solidification on a karst roof, characterized by: Including karst environment simulation system, grouting system, and data acquisition system; The karst environment simulation system comprises a transparent test box, a karst cavity structure (5) and a pile impact failure simulation unit; the inner cavity of the transparent test box is filled with a base bearing layer (3), a soft rock layer (4) around the cave, a thin roof structure (6), a fluidized soil layer (7) and an overlying rock layer (8) in sequence from bottom to top; the karst cavity structure (5) is a hollow cubic structure; the karst cavity structure (5) has a cavity inside; the karst cavity structure (5) is buried in the soft rock layer (4) around the cave; the upper surface of the karst cavity structure (5) is against the lower surface of the thin roof structure (6), and the lower surface rests on the upper surface of the base bearing layer (3); The pile topping failure simulation unit comprises a steel casing (2) and an iron pipe (1); the steel casing (2) is a cylindrical structure; the lower end of the steel casing (2) is placed on the upper surface of a thin top plate structure (6); the lower end of the steel casing (2) is open and blocked by the thin top plate structure (6); the upper end of the steel casing (2) extends out of the fluidized soil layer (7) and the overlying rock layer (8); the iron pipe (1) is accommodated in the inner cavity of the steel casing (2); The grouting port of the grouting system is covered in a fluidized soil layer (7); The data acquisition system comprises a computer-controlled monitoring system (11), an earth pressure gauge (13), a strain gauge (14), a flow meter and a pressure sensor; the earth pressure gauge (13) is buried in the fluidized soil layer (7); the elevation of the earth pressure gauge (13) is higher than the elevation of the grouting port; the strain gauge (14) is attached to the upper surface of the thin top plate structure (6); the grouting system is equipped with a flow meter and a pressure sensor; the earth pressure gauge (13), the strain gauge (14), the flow meter and the pressure sensor are all connected to the computer-controlled monitoring system (11).

2. The experimental device for simulating laminar flow plastic soil grouting and solidification on karst roof according to claim 1, characterized in that: The transparent test box is made of organic glass.

3. The experimental device for simulating laminar flow plastic soil grouting and solidification on karst roof according to claim 1, characterized in that: The karst cavity structure (5) is cast with cement.

4. The experimental device for simulating laminar flow plastic soil grouting and solidification on karst roof according to claim 1, characterized in that: The thin top plate structure (6) is integrally cast with cement.

5. The experimental device for simulating laminar flow plastic soil grouting and solidification on karst roof according to claim 1, characterized in that: The grouting system comprises four groups of grouting units; each group of grouting units comprises a slurry storage tank (12), a grouting pump (10) and a grouting pipe (9); the grouting pump (10) is connected to the slurry storage tank (12) and the grouting pipe (9); the grouting ports of the four grouting pipes (9) are arranged around the steel casing (2).

6. The experimental device for simulating laminar flow plastic soil grouting and solidification on karst roof according to claim 1, characterized in that: The base bearing layer (3) is a hard rock layer; the overlying rock layer (8) is a soft rock layer.

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