Testing device suitable for layered rock mass tunnel grouting reinforcement

Abstract

A tunnel grouting reinforcement testing device suitable for stratified rock mass comprises the stratified rock mass formed by mutually stacked rock slices, the stratified rock mass is inserted into a mounting groove of a rock mass mounting frame, and the rock mass mounting frame is placed in a grouting model device. The grouting model device is matched with a water injection device, a grouting device, a ground stress loading device and a standard test piece processing device. The layered rock mass is mounted through the rock mass mounting frame, and the grouting reinforcement effect of the layered rock mass with different grouting pressures, different joint cohesion and internal friction angles and different joint crossing angles under the combined action of different water pressures and different ground stress environments is simulated and obtained in the grouting model device.

Description

Technical Field

[0001] The utility model relates to the field of underground engineering disaster prevention and control, and particularly relates to a grouting reinforcement test device suitable for layered rock mass tunnels. Background Technique

[0002] With the booming development of infrastructure construction in China, a large number of infrastructure projects such as highways, railways, water conservancy and hydropower, and urban underground spaces have been put into construction. At present, China has become the country with the largest construction scale and difficulty of tunnels and underground projects in the world. During the construction of tunnels and underground projects, adverse geology such as faults, fractured rock masses, and soft strata are often encountered, which are extremely likely to induce geological disasters such as surrounding rock collapses, water inrusions and mud outflows, and water inrusions and sand outflows. Sudden geological disasters cause huge losses to construction personnel and machinery, and also seriously threaten the hydrology and ecological environment in the tunnel site area.

[0003] Grouting is an effective means to deal with adverse geology and improve the surrounding rock conditions, and has been widely used in many fields such as railways, highways, water conservancy, and mines. Grouting can structure the surrounding rock and soil mass around the tunnel, treat the fault fracture zone, block the sudden water inrush in the tunnel, and treat adverse geological structures such as karst and underground rivers to ensure the construction and operation safety of tunnels and other underground projects. However, due to the extremely complex process of slurry migration, involving slurry characteristics, formation characteristics, and the fluid-solid coupling effect between the two, the progress of theoretical research is relatively slow and cannot effectively guide the practice of grouting projects. Model tests are an important method for studying the diffusion law of slurry in the formation and the reinforcement mechanism, and have been widely used at home and abroad.

[0004] However, most of the current model tests use homogeneous rock and soil masses for testing, and cannot consider the influence of the bedding dip angle in layered rock masses on the slurry diffusion and the slurry reinforcement effect. On the other hand, by using different grouting materials to reinforce layered rock masses, after the specimens are cured, uniaxial and conventional triaxial tests are carried out to obtain the physical and mechanical parameters of the specimens, and the grouting reinforcement effect is quantitatively evaluated. This method focuses on the mechanical property analysis of the reinforced body and cannot intuitively show the diffusion and plugging process of the slurry in the cracks. In addition, this method does not consider the influence of initial ground stress and water pressure, and it is difficult to apply to the grouting reinforcement effect of layered rock masses under different ground stresses and different water pressures.

[0005] Therefore, there is an urgent need for a grouting reinforcement test device suitable for layered rock mass tunnels that can visually simulate the grouting reinforcement effect of layered rock masses under different ground stresses and different water pressures. Content of the Utility Model

[0006] The purpose of the utility model is to provide a grouting reinforcement test device suitable for layered rock mass tunnels, which can visually simulate the grouting reinforcement effect of layered rock masses under the combined action of ground stress and water pressure with different grouting pressures, different joint cohesion and internal friction angles, and different joint crossing angles.

[0007] To achieve the above object, the utility model provides a grouting reinforcement test device applicable to a layered rock mass tunnel, which includes a layered rock mass composed of mutually stacked rock flakes. The layered rock mass is inserted into the installation groove of a rock mass installation frame, and the rock mass installation frame is placed in a grouting model device. The grouting model device is equipped with a water injection device, a grouting device, a ground stress loading device, and a standard specimen processing device. The ground stress loading device includes a press that applies pressure to the movable side of the box body. The grouting model device includes a box body formed by airtight connection of steel plates, and the box body is provided with a water injection port, a grouting hole, a slurry outlet hole, and a transparent grouting observation board. The water injection device includes a water tank with adjustable height, and the water tank is connected to the box body through a water injection pipe to form different groundwater pressures on the rock mass. The grouting device includes a grouting steel pipe drilled into the layered rock mass. The grouting steel pipe is radially provided with grouting ports arranged along the axial direction. The grouting steel pipe is connected to an air pump and a first grouting pump in a first grouting barrel through a first grouting pipe. A first mixer is provided in the first grouting barrel. After the layered rock mass is grouted, a solidified body is formed, and core samples are obtained from the solidified body through the standard specimen processing device. The utility model uses the ground stress loading device and the water injection device to simulate different water pressures and different ground stresses of underground rock masses, truly restoring the construction site environment. The grouting situation on site is simulated through the grouting model device and the grouting device, and the data obtained by the monitoring device is used to guide the on-site construction, greatly improving the seepage grouting reinforcement effect of rock masses in complex underground environments during tunnel excavation. After the layered rock mass is grouted, a solidified body is formed. The solidified body is cured for 3 days, 7 days, and 28 days. By observing the stone formation efficiency of the grouted solidified body under different grouting pressures and water pressure environments, the reinforcement effects under various factors are preliminarily analyzed to initially analyze the grouting reinforcement effects under various conditions. Then, the solidified body is cut by a cutting machine of the standard specimen processing device, and core samples are formed by drilling with a core drill. The core samples are then cut and polished, and then uniaxial compression tests and shear tests are performed on the core samples to test the compressive strength and shear strength of the core samples. Through comprehensive analysis of the mechanical properties of the core samples, the action effects of reinforcing the layered rock mass under various conditions are obtained. Comprehensive analysis of the mechanical properties of the core samples can be carried out using existing analysis methods.

[0008] The press is connected to a pressure plate through a hydraulic ejector rod, and the pressure plate applies pressure to the movable steel plate to simulate the ground stress received by the rock mass.

[0009] The movable steel plate at the top of the box body is provided with a water injection port, and the box body is provided with a grouting hole and a slurry outlet hole arranged vertically on the side. Transparent grouting observation boards with different heights are respectively arranged on the four sides of the box body to facilitate observing the grouting effect of the grouting slurry.

[0010] The water tank is connected to a chain hoist, and the chain hoist drives the water tank to move up and down to simulate the groundwater system environment with different water pressures.

[0011] The grouting model device is connected with a monitoring device, and the monitoring device includes sensors, which include stress gauges, strain gauges, flow meters and pressure monitors; the stress gauges are placed in the grouting model device, the strain gauges are pasted on the inner wall of the box, the flow meters are placed on the pipelines connected to the water injection pipes, grouting steel pipes and water outlet holes, and the pressure monitors are placed in the first grouting pipe. The monitoring device realizes the stress of the rock mass in the grouting model device and the stress change situation, has the flow change situations of pressure, water injection and grouting, realizes restoring the water vapor content and in-situ stress change situation of the rock mass in the underground environment where it occurs, and provides accurate data support for the grouting work at the actual site.

[0012] The water injection port and the water injection pipe are sealed with epoxy resin AB glue, and the grouting hole and the grouting steel pipe are sealed with epoxy resin AB glue to prevent water and grouting slurry from leaking out.

[0013] The standard specimen processing device includes a cutting machine, a core drilling machine and a grinding machine.

[0014] Adopting the above technical solution, the layer-like rock mass composed of mutually laminated rock slices in the layer-like rock mass tunnel grouting reinforcement test device is inserted into the installation groove of the rock mass installation frame. The grouting situation of the layer-like rock mass tunnel under different water pressures and in-situ stresses at the construction site is simulated through the grouting model device and the in-situ stress loading device, and the grouting effect is evaluated through the grouting reinforcement effect device. At the same time, the best grouting parameters are obtained by the monitoring device. Finally, the cohesive force and internal friction angle between the laminated rock slices of the target grouted rock mass with different parameters obtained are detected, providing accurate data support for the actual tunnel passing through the layer-like rock mass. Description of the Drawings

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0016] Figure 1 is a schematic structural diagram of a tunnel seepage grouting reinforcement test device for simulating different water pressures and in-situ stresses according to the present invention;

[0017] Figure 2 is a schematic structural diagram of the installation of the grouting steel pipe in the present invention;

[0018] Figure 3 is a schematic structural diagram of the grouting model device in the present invention;

[0019] Figure 4 is a schematic structural diagram of the rock mass installation frame in the present invention;

[0020] Figure 5 is a schematic diagram of the layered rock mass structure of the horizontal plug-in rock mass installation frame in the utility model;

[0021] Figure 6 is a schematic diagram of the layered rock mass structure of the inclined plug-in rock mass installation frame in the utility model. Specific embodiments

[0022] Next, in combination with the accompanying drawings in the embodiments of the present utility model, the technical solutions in the embodiments of the present utility model will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the protection scope of the present utility model.

[0023] Such as Figures 1-6 , a grouting reinforcement test device suitable for layered rock mass tunnels, including a layered rock mass composed of mutually stacked rock flakes. The layered rock mass is inserted into the installation groove 73 of the rock mass installation frame 70, and the rock mass installation frame is placed in the grouting model device. The grouting model device is equipped with a water injection device, a grouting device, a ground stress loading device, and a standard specimen processing device; the grouting model device includes a box body 10 formed by hermetically connecting steel plates. The box body 10 is provided with a water injection port, a grouting hole, a slurry outlet hole, and a transparent grouting observation board.

[0024] As a structural preference, the ground stress loading device includes a press 11 that applies pressure to the movable side of the box body 10. The press 11 is connected to a pressure plate 12 through a hydraulic jack rod, and the pressure plate 12 applies pressure to the movable steel plate 30 to simulate the real ground stress received by the rock mass underground.

[0025] The movable steel plate 30 on the top of the box body 10 is provided with a water injection port 24. The side of the box body is provided with a grouting hole 26 and a slurry outlet hole 25 arranged up and down. Transparent grouting observation boards with different heights are respectively arranged on the four sides of the box body.

[0026] As a structural preference, the water injection device 14 includes a water tank 16 with adjustable height. The water tank 16 is connected to the box body 10 through a water injection pipe 13 to form different groundwater pressures on the rock mass; the water tank 16 is connected to a chain hoist 15, and the chain hoist 15 drives the water tank 16 to move up and down to realize the change of water pressure.

[0027] As a structural preference, the grouting device includes a grouting steel pipe 22 drilled into the layered rock mass. The grouting steel pipe 22 is radially provided with grouting ports 52 arranged along the axial direction. The grouting steel pipe 22 is connected to an air pump 1 and a first grouting pump 2 in a first grouting barrel 3 through a first grouting pipe 21; a first stirrer 4 is arranged in the first grouting barrel 3 to increase the uniformity of the grouting slurry.

[0028] As the structural optimization monitoring device 7, the monitoring device 7 includes sensors, and the sensors include a stress gauge, a strain gauge, a flow velocity meter, and a pressure monitor; the stress gauge is placed in the grouting model device, the strain gauge is pasted on the inner wall of the box body 10, the flow velocity meter is placed on the pipeline connected to the water injection pipe, the grouting steel pipe 22, and the water outlet hole, and the pressure monitor is placed in the first grouting pipe 21.

[0029] To improve the sealing performance, the water injection port 24 and the water injection pipe 13 are sealed with epoxy resin AB glue, and the grouting hole 26 and the grouting steel pipe 22 are sealed with epoxy resin AB glue.

[0030] As a structural optimization, the standard specimen processing device includes a cutting machine, a core drilling machine, and a grinding machine. The cutting machine of the standard specimen processing device cuts the reinforced body, drills and takes cores through the core drilling machine to form core samples, then cuts and grinds the core samples, and then conducts uniaxial compression tests and shear tests on the core samples to test the compressive strength and shear strength of the core samples. Through comprehensive analysis of the mechanical properties of the core samples, the effect of reinforcing the layered rock mass under various conditions is obtained. Comprehensive analysis of the mechanical properties of the core samples can be carried out by using existing analysis methods.

[0031] As a specific implementation, the platform size of the box body 10 is 1000mm * 1000mm * 1000mm. The model box is made of 10mm thick steel plates, which can meet the requirement of the maximum grouting pressure of 10Mpa. The side, bottom, and top are all connected by high-strength bolts. To ensure the airtightness of the model box, the joints are sealed with 2mm thick rubber gaskets and sealant. Transparent grouting observation plates with different heights are arranged on the sides, made of high-strength plexiglass. The plexiglass is 225mm * 100mm, and the bottom of the plexiglass is 225mm, 450mm, 675mm, and 900mm away from the bottom of the model box in sequence. A grouting hole with a radius of 25mm is reserved at the top of the box body, and a slurry outlet hole with a radius of 5mm is reserved at the bottom of the side. After the above-mentioned layered rock mass specimens are placed in the box body, the movable steel plate 30 is embedded at the open mouth of the box body for sealing, and the joints are sealed with thick rubber gaskets and sealant.

[0032] The specific installation process of the layered rock mass composed of mutually stacked rock flakes is as follows:

[0033] Step 1: Sampling. The size of this rock mass installation frame 70 is 150mm * 150mm * 150mm. The left and right sides of the rock mass installation frame 70 device are solid wood boards, and the front and rear sides are surrounded by equally spaced installation grooves 73. The upper side is surrounded by wooden strips and the center is empty, which is convenient for gradually arranging different numbers of grouting holes. The lower side is a solid wood board. All eight corners of the rock mass installation frame 70 are fixed with gaskets and bolts 72, which is convenient for disassembling and maintaining the layered rock mass after grouting.

[0034] Step 2: Drill a plurality of round holes with different sizes and quantities at regular intervals on each piece of layered rock mass, with the inclination angles being 0° and 45°.

[0035] Step 3: Insert the layered rock mass with drilled round holes layer by layer into the installation groove 73 and fix the connecting bolts. Inject cement slurry into each hole, requiring high water pressure and low flow rate to be injected into the hole to ensure that each layer is filled with cement slurry. Use a glass rod to stir to prevent the generation of bubbles. After the slurry solidifies, disassemble the rock mass installation frame 70, take out the specimen, and cure it for 28 days to make the cement completely solidify. Place the fabricated specimen on a direct shear apparatus in the rock laboratory to conduct direct shear tests under different in-situ stresses. According to the formula, the cohesion and internal friction angle of this specimen can be obtained. Repeat the above steps by making the same number of but different-sized round holes on the layered rock mass to obtain the cohesion and internal friction angle of the layered rock mass. Repeat the above steps by making round holes with the same size but different quantities on the layered rock mass to obtain the cohesion and internal friction angle of the layered rock mass, so as to achieve the effect of grouting reinforcement of the layered rock mass with different grouting pressures, different joint cohesions and internal friction angles, and different joint crossing angles.

[0036] The utility model simulates different cohesions and internal friction angles of the structural plane of the tunnel passing through the layered rock mass by adjusting the hole size and quantity, and solves the problems of complex processing and difficult production of standard rock specimens in the existing test for measuring the cohesion and internal friction angle of layered rocks. In the utility model, a plurality of round holes with different sizes and quantities are drilled at regular intervals on each rock slice, and the rock slices with drilled grouting holes are inserted layer by layer into the installation groove. Inject cement slurry into each grouting hole, requiring high water pressure and low flow rate to be injected into the hole to ensure that each layer is filled with cement slurry. Use a glass rod to stir to prevent the generation of bubbles. After the slurry solidifies, disassemble the rock slices to form a solidified body and cure it for 28 days to make the cement completely solidify. Place the fabricated specimen on an indoor direct shear apparatus to conduct direct shear tests under different normal stresses, and the cohesion and internal friction angle of this specimen can be obtained. Repeat the above steps by making the same number of but different-sized grouting holes on the rock slice to obtain the cohesion and internal friction angle of the layered rock mass. Repeat the above steps by making grouting holes with the same size but different quantities on the rock slice to obtain the cohesion and internal friction angle of the layered rock mass, so as to achieve the effect of grouting reinforcement of the layered rock mass with different grouting pressures, different joint cohesions and internal friction angles, and different joint crossing angles.

[0037] The specific grouting steps in the grouting device are as follows:

[0038] ① First, drill two parallel grouting steel pipes and a grouting effect observation pipe with zero grouting pressure in the rock mass. The two parallel grouting steel pipes are the grouting steel pipe 22 and the first grouting steel pipe 23 respectively. The first grouting steel pipe 23 is provided with first grouting holes 44 at equal intervals, and the grouting steel pipe 22 is provided with grouting ports 52 at equal intervals.

[0039] ② The distribution of each grouting steel pipe is symmetrically distributed up and down, and the spacing between adjacent holes is adjusted in a timely manner according to the situation;

[0040] ③ The grouting pressure of the grouting steel pipe is greater than the water pressure of the occurrence environment; for the grouting effect observation pipe with zero grouting pressure, the grouting effect observation pipe is embedded in the rock mass, and the porosity of the embedded rock mass only allows the grouting slurry to enter. The grouting effect is judged in real time according to the concentration of the grouting slurry flowing out of the grouting effect observation pipe.

[0041] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention without departing from the principle and purpose of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A grouting reinforcement test device suitable for layered rock tunnels, characterized in that: The invention comprises a layered rock mass composed of mutually stacked rock slices, the layered rock mass is inserted into a mounting groove (73) of a rock mass mounting frame (70), the rock mass mounting frame is placed in a grouting model device, the grouting model device is equipped with a water injection device, a grouting device, a ground stress loading device and a standard specimen processing device; the ground stress loading device comprises a press (11) capable of applying pressure to a movable side of a box body (10); the grouting model device comprises a box body (10) formed by a sealed connection of steel plates, the box body (10) being provided with a water injection port (24), a grouting hole (26), a grouting outlet hole (25) and a transparent grouting observation hole (26). The water injection device (14) comprises a water tank (16) with adjustable height, the water tank (16) being connected to the box body (10) via a water injection pipe (13) to form different underground water pressures on the rock mass; the grouting device comprises a grouting steel pipe (22) drilled into the layered rock mass, the grouting steel pipe (22) being radially provided with grouting ports (52) arranged along the axial direction, the grouting steel pipe (22) being connected to an air pump (1) and a first grouting pump (2) in a first grouting barrel (3) via a first grouting pipe (21); after the grouting of the layered rock mass is completed, a reinforcement body is formed, and a core sample is obtained from the reinforcement body by a standard specimen processing device.

2. A grouting reinforcement testing device for layered rock tunnels according to claim 1, characterized in that: The press (11) is connected to a pressure plate (12) via a hydraulic push rod, and the pressure plate (12) applies pressure to the movable steel plate (30).

3. The grouting reinforcement testing device for layered rock tunnel according to claim 1 is characterized in that: The movable steel plate (30) on the top of the box body (10) is provided with a water injection port (24), and the side of the box body is provided with grouting holes (26) and grouting outlet holes (25) arranged up and down, and transparent grouting observation panels of different heights are respectively provided on the four sides of the box body.

4. The grouting reinforcement testing device for layered rock tunnel according to claim 1, characterized in that: The water tank (16) is connected to the chain hoist (15), and the chain hoist (15) drives the water tank (16) to move up and down.

5. The grouting reinforcement testing device for layered rock tunnel according to claim 1, characterized in that: A first mixer (4) is provided in the first grouting barrel (3).

6. The grouting reinforcement testing device for layered rock tunnel according to claim 1, characterized in that: The grouting model device is connected to a monitoring device (7), the monitoring device (7) comprising a sensor, the sensor comprising a stress gauge, a strain gauge, a flow meter and a pressure monitoring gauge; the stress gauge is placed in the grouting model device, the strain gauge is adhered to the inner wall of the box (10), the flow meter is placed on the pipeline connecting the water injection pipe, the grouting steel pipe (22) and the water outlet, and the pressure monitoring gauge is placed in the first grouting pipe (21).

7. The grouting reinforcement testing device for layered rock tunnel according to claim 1, characterized in that: The water injection port (24) and the water injection pipe (13) are sealed by epoxy resin AB glue, and the grouting hole (26) and the grouting steel pipe (22) are sealed by epoxy resin AB glue.

8. The grouting reinforcement testing device for layered rock tunnels according to claim 1, characterized in that: The standard specimen processing device comprises a cutting machine, a coring machine and a grinding machine.

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