Mining-induced fractured rock mass grouting test device and method for synchronously measuring permeability in real time

Abstract

The invention belongs to the technical field of mining-induced fractured rock mass grouting filling, and particularly relates to a mining-induced fractured rock mass grouting test device and method for synchronously measuring permeability in real time, and the device comprises a base which is placed in a pressure applying device and is internally provided with a cavity for storing a sample; the gas inlet part is arranged at the bottom of the cavity, the exhaust end of the gas inlet part is in contact with the bottom of the sample, the gas inlet end of the gas inlet part is located on the outer side of the base, and the gas inlet part is used for being communicated with a gas source and providing high-pressure gas for the sample; the exhaust part is arranged at the top of the cavity, the air inlet end of the exhaust part is in contact with the top of the sample, the exhaust part is arranged in the piston, the piston is slidably arranged in the cavity, the exhaust end of the exhaust part is located on the outer side of the piston, and the top of the piston is installed at the pressure applying end of the pressure applying device; the grouting part wraps the side wall of the sample, the bottom of the grouting part is fixedly connected with the base, and the liquid outlet end of the grouting part communicates with the cavity and is used for injecting grout into the sample; the displacement sensor is used for detecting the distance between the pressure applying end of the pressure applying device and the top of the cavity.

Description

Technical Field

[0001] The invention belongs to the technical field of grouting filling of mining fractured rock mass, and in particular relates to a mining fractured rock mass grouting test device and method for real-time synchronous permeability measurement. Background Art

[0002] During coal mining, due to the impact of mining, cracks in the overburden strata continue to develop, and the porosity and permeability continue to increase. When the mining cracks connect to the aquifer, water inrush accidents occur, causing casualties and property losses. Grouting technology can effectively fill the mining cracks in the overburden rock to form a water-proof rock layer, thereby preventing water inrush accidents. In this process, the permeability of the fractured rock mass continues to decrease under the filling effect of the slurry, and existing methods cannot reproduce and measure this process synchronously in real time.

[0003] Therefore, there is an urgent need for a mining fracture rock mass grouting test device and method for real-time synchronous permeability measurement. Summary of the invention

[0004] The purpose of the present invention is to provide a mining fracture rock mass grouting test device and method for real-time synchronous permeability measurement to solve the above problems.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] The mining fracture rock mass grouting test device for real-time synchronous permeability measurement includes:

[0007] A base is placed in the pressure-applying device, wherein a chamber for storing a sample is provided in the base;

[0008] An air inlet portion is arranged at the bottom of the chamber, an exhaust end of the air inlet portion contacts the bottom of the sample, an air inlet end of the air inlet portion is located outside the base, and the air inlet portion is used to communicate with a gas source and inject high-pressure gas into the chamber;

[0009] An exhaust portion is arranged at the top of the chamber, an air inlet end of the exhaust portion contacts the top of the sample, the exhaust portion is arranged in a piston, the piston is slidably arranged in the chamber, the exhaust end of the exhaust portion is located outside the piston, and the top of the piston is mounted on the pressure end of the pressure device;

[0010] A grouting part, wrapped around the side wall of the sample, the bottom of the grouting part is fixedly connected to the base, and the liquid outlet end of the grouting part is connected to the chamber, and is used to inject slurry into the chamber;

[0011] The displacement sensor is used to detect the height of the piston exceeding the top of the chamber to obtain the height of the sample.

[0012] According to the above-mentioned mining fracture rock mass grouting test device for real-time synchronous permeability measurement, the grouting part includes:

[0013] An inner grouting tube, wherein the bottom of the inner grouting tube is axially connected to the base, the chamber is arranged in the inner grouting tube, and a plurality of grouting holes for communicating with the chamber are evenly opened on the side wall of the inner grouting tube;

[0014] An outer cylinder is coaxially arranged outside the inner grouting cylinder, the bottom of the outer cylinder is fixedly connected to the top of the base, and the top of the outer cylinder is fixedly connected to the top of the inner grouting cylinder;

[0015] The inner wall of the outer tube and the outer wall of the inner grouting tube together form a slurry temporary storage cavity, and the slurry temporary storage cavity is connected to the liquid inlet ends of the plurality of grouting holes;

[0016] The slurry temporary storage chamber is connected to a grouting port, and the grouting port is arranged on the outer cylinder.

[0017] According to the above-mentioned mining fracture rock mass grouting test device for real-time synchronous permeability measurement, the air inlet part includes:

[0018] A first honeycomb-shaped porous air cavity is arranged at the bottom of the chamber, an air inlet end of the first honeycomb-shaped porous air cavity is connected to an exhaust end of an air inlet pipeline, the air inlet pipeline is buried in the base, an air inlet of the air inlet pipeline is arranged on a side wall of the base, and the air inlet is used to connect to an air source;

[0019] A breathable gauze is laid between the exhaust end of the first honeycomb porous air cavity and the sample.

[0020] According to the above-mentioned mining fracture rock mass grouting test device for real-time synchronous permeability measurement, the exhaust part includes:

[0021] The second honeycomb porous air cavity is slidably arranged in the chamber, the second honeycomb porous air cavity is fixedly connected to the bottom of the piston, the air inlet end of the second honeycomb porous air cavity is in contact with and connected to the top of the sample, the exhaust end of the second honeycomb porous air cavity is connected to the air inlet end of an exhaust pipe, the exhaust pipe is buried in the piston, and the air outlet of the exhaust pipe is opened on the side wall of the piston.

[0022] According to the above-mentioned mining fracture rock mass grouting test device for real-time synchronous permeability measurement, the displacement sensor includes:

[0023] A linear variable differential transformer, wherein the fixed end of the linear variable differential transformer is fixedly connected to the top of the inner grouting cylinder, and the movable end of the linear variable differential transformer is fixedly connected to the pressure end of the pressure device.

[0024] According to the above-mentioned mining fracture rock mass grouting test device for real-time synchronous permeability measurement, the pressure device includes:

[0025] An axial displacement control device, wherein the base is placed in the axial displacement control device, and the movable end of the axial displacement control device is fixedly connected to the top of the piston;

[0026] The active end of the linear variable differential transformer is fixedly connected to the active end of the axial displacement control device.

[0027] The mining fractured rock mass grouting test method with real-time synchronous permeability measurement is based on the above-mentioned mining fractured rock mass grouting test device with real-time synchronous permeability measurement, and comprises the following steps:

[0028] Filling the sample into the chamber and controlling the piston to contact the sample;

[0029] The pressure end of the pressure device is driven to drive the piston to press the sample downward, thereby adjusting the porosity of the sample, and detecting the displacement of the pressure end of the pressure device through a displacement sensor;

[0030] After reaching the target initial porosity, the pressure is released to a stable value and the loading pressure at the pressure end of the pressure applying device is kept constant, and the gas source and the grouting mechanism are turned on to inject grout into the chamber to start the seepage grouting test;

[0031] Controlling the grouting part to inject slurry into the grouting mechanism so that the slurry is injected into the chamber;

[0032] Connecting a gas source to the gas inlet portion, and controlling the gas source to inject high-pressure gas into the chamber through the gas inlet portion;

[0033] Connecting a gas collecting device to the exhaust portion;

[0034] acquiring intake pressure data based on the intake amount of the intake portion;

[0035] acquiring exhaust pressure data based on the exhaust volume of the exhaust portion;

[0036] Acquiring grouting pressure data of the grouting part;

[0037] The permeability and nonlinear seepage factor are obtained based on the air intake volume, air intake pressure data, exhaust volume, exhaust pressure data, and grouting pressure data.

[0038] Compared with the prior art, the present invention has the following advantages and technical effects:

[0039] In the present invention, by providing axial stress to the sample, on the one hand, the different initial porosities of the mined fractured rock mass can be changed, and on the other hand, the axial stress can be provided; nitrogen can be used as the seepage fluid, which can reduce the mutual influence between the gas and the slurry during the grouting process; the gas flows from bottom to top and can overcome the influence of the gas's own gravity; by monitoring parameters such as the slurry flow rate and the gas flow rate during the measurement of the grouting test, the permeability change law during the grouting process of the mined fractured rock mass can be obtained after computer processing.

[0040] Under the premise of ensuring that the grouting pressure and the gas pressure at the air inlet remain unchanged, the present invention can obtain the permeability change characteristics of the mined fractured rock mass under different axial loading pressures by changing the axial load; ensure that the axial load and the grouting pressure remain unchanged, and obtain the permeability change characteristics of the mined fractured rock mass under different pore pressure conditions by changing the gas pressure at the air inlet; ensure that the axial load and the gas pressure at the air inlet remain unchanged, and obtain the permeability change characteristics of the mined fractured rock mass under different grouting pressure conditions by changing the grouting pressure.

[0041] The present invention can realize the permeability variation characteristics of the mining fractured rock mass under different initial porosities, different continuous grading conditions and different slurry properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below 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 labor:

[0043] Figure 1 It is a schematic diagram of the structure of the present invention;

[0044] Figure 2 This is a schematic diagram of a second honeycomb porous air cavity structure of the present invention;

[0045] Figure 3 It is a structural schematic diagram of the grouting part of the present invention;

[0046] Figure 4 It is a curve diagram showing the variation of permeability of the fractured rock mass with time during the grouting process of the present invention;

[0047] Figure 5 It is a curve diagram showing the variation of the nonlinear seepage factor of the fractured rock mass during the grouting process of the present invention over time;

[0048] Among them, 1. axial displacement control device; 2. piston; 3. air outlet; 4. linear variable differential transformer; 5. bolt; 6. second honeycomb porous air cavity; 7. outer cylinder; 8. inner grouting cylinder; 9. first honeycomb porous air cavity; 10. grouting port; 11. sealing ring; 12. air inlet; 13. base; 14. breathable gauze. DETAILED DESCRIPTION

[0049] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0051] Embodiment 1:

[0052] Reference Figures 1 to 3 This embodiment discloses 1. A mining fracture rock mass grouting test device for real-time synchronous permeability measurement, comprising:

[0053] A base 13 is placed in the pressure device, and a chamber for storing a sample is provided in the base 13;

[0054] An air inlet is arranged at the bottom of the chamber, an exhaust end of the air inlet contacts the bottom of the sample, an air inlet end of the air inlet is located outside the base 13, and the air inlet is used to communicate with the gas source and inject high-pressure gas into the chamber;

[0055] The exhaust part is arranged at the top of the chamber, the air inlet end of the exhaust part contacts the top of the sample, the exhaust part is arranged in the piston 2, the piston 2 is slidably arranged in the chamber, the exhaust end of the exhaust part is located outside the piston 2, and the top of the piston 2 is installed on the pressure end of the pressure device;

[0056] The grouting part is wrapped around the side wall of the sample, the bottom of the grouting part is fixedly connected to the base 13, and the liquid outlet end of the grouting part is connected to the chamber for injecting slurry into the chamber;

[0057] The displacement sensor is used to detect the height of the piston 2 exceeding the top of the chamber to obtain the height of the sample.

[0058] When in use, fill the sample in the chamber, put the piston 2 into the top of the chamber to contact the sample, connect the piston 2 to the pressure end of the pressure device; connect the grouting mechanism to the grouting part, connect the gas source to the air inlet, connect the gas collection device to the exhaust part, arrange the data acquisition device and install the valve, drive the pressure end of the pressure device to drive the piston 2 to press the sample to adjust the porosity of the sample, keep the loading pressure of the pressure end of the pressure device unchanged, turn on the gas source and the grouting mechanism to grout the sample to start the seepage grouting test; analyze and process the data obtained by the computer to obtain the permeability under the grouting conditions of the mined fractured rock mass. In the present invention, by providing axial stress to the sample, on the one hand, the different initial porosities of the mined fractured rock mass are changed, and on the other hand, it can be used to provide axial stress; nitrogen can be used as the seepage fluid, which can reduce the mutual influence between the slurry and the grouting process; the gas flows from bottom to top to overcome the influence of the gas's own gravity; by monitoring the parameters such as the slurry flow rate and the gas flow rate during the measurement of the grouting test, the permeability change law during the grouting of the mined fractured rock mass can be obtained after computer processing;

[0059] Under the premise of ensuring that the grouting pressure and the gas pressure at the air inlet remain unchanged, the present invention can obtain the permeability change characteristics of the mined fractured rock mass under different axial loading pressures by changing the axial load; ensure that the axial load and the grouting pressure remain unchanged, and obtain the permeability change characteristics of the mined fractured rock mass under different pore pressure conditions by changing the gas pressure at the air inlet; ensure that the axial load and the gas pressure at the air inlet remain unchanged, and obtain the permeability change characteristics of the mined fractured rock mass under different grouting pressure conditions by changing the grouting pressure.

[0060] The present invention can realize the permeability variation characteristics of the mining fractured rock mass under different initial porosities, different continuous grading conditions and different slurry properties.

[0061] As an optional embodiment, the grouting unit includes:

[0062] An inner grouting tube 8, the bottom of which is axially connected to the base 13, a chamber is arranged in the inner grouting tube 8, and a plurality of grouting holes for communicating with the chamber are evenly opened on the side wall of the inner grouting tube 8;

[0063] The outer cylinder 7 is coaxially arranged outside the inner grouting cylinder 8, the bottom of the outer cylinder 7 is fixedly connected to the top of the base 13, and the top of the outer cylinder 7 is fixedly connected to the top of the inner grouting cylinder 8;

[0064] The inner wall of the outer cylinder 7 and the outer wall of the inner grouting cylinder 8 are combined to form a slurry temporary storage chamber, and the slurry temporary storage chamber is connected to the liquid inlet ends of the plurality of grouting holes;

[0065] The slurry temporary storage chamber is connected to a grouting port 10 , and the grouting port 10 is opened on the outer tube 7 .

[0066] A number of grouting holes evenly arranged on the side wall of the inner grouting tube 8 are used to ensure uniform injection of the slurry.

[0067] Sealing rings 11 are provided at the joints of the outer tube 7 and the inner grouting tube 8 to prevent the slurry from leaking out.

[0068] The grouting port 10 is connected to the grouting system, and the grouting system includes a grouting tank, an air pump, a pressure-suppressing tank, a mud valve, an air inlet valve, a pressure reducing valve, an exhaust pipe, an exhaust valve, a grouting hose, a pressure gauge, a flow meter, and a grouting port. The air pump, the pressure-suppressing tank, the grouting tank, and the grouting port 10 are connected in sequence; the grouting tank is provided with a mixer; the pressure reducing valve is arranged at the outlet of the pressure-suppressing tank, the air inlet valve is arranged at the inlet of the pressure-suppressing tank, an exhaust pipe is arranged between the pressure reducing valve and the pressure-suppressing tank, and an exhaust valve is arranged on the exhaust pipe; the mud valve is at the outlet of the grouting tank; a pressure gauge is arranged at the inlet of the grouting tank, and a pressure gauge and a flow meter are arranged in sequence at the grouting port. The grouting system is a prior art and will not be described in detail here.

[0069] As an optional implementation, the air intake portion includes:

[0070] The first honeycomb porous air cavity 9 is arranged at the bottom of the chamber, the air inlet end of the first honeycomb porous air cavity 9 is connected to the exhaust end of the air inlet pipeline, the air inlet pipeline is buried in the base 13, the air inlet port 12 of the air inlet pipeline is arranged on the side wall of the base 13, and the air inlet port 12 is used to connect with the air source;

[0071] An air-permeable gauze 14 is laid between the exhaust end of the first honeycomb porous air cavity 9 and the sample.

[0072] The first honeycomb porous air cavity 9 and the air-permeable gauze 14 are provided to ensure uniform gas entry.

[0073] As an optional embodiment, the exhaust unit includes:

[0074] The second honeycomb porous air cavity 6 is slidably arranged in the chamber, the second honeycomb porous air cavity 6 is fixedly connected to the bottom of the piston 2, the air inlet end of the second honeycomb porous air cavity 6 is in contact with and connected to the top of the sample, the exhaust end of the second honeycomb porous air cavity 6 is connected to the air inlet end of the exhaust pipe, the exhaust pipe is buried in the piston 2, and the air outlet 3 of the exhaust pipe is opened on the side wall of the piston 2.

[0075] The second honeycomb porous air cavity 6 is provided to ensure uniform gas discharge.

[0076] The air inlet 12 and the air outlet 3 are both connected to the gas seepage system, which includes a high-pressure nitrogen cylinder, a pressure reducing valve, a flow meter, a pressure sensor, a gas collecting device, an air inlet, an air outlet and an air pipe. The air inlet 12 is connected to the high-pressure nitrogen cylinder, and the air outlet 3 is connected to the gas collecting device. A flow meter and a pressure reducing valve are arranged at one end near the air inlet 12 to control the air flow and pressure, and pressure sensors are arranged at the air inlet 12 and the air outlet 3.

[0077] The first honeycomb porous air cavity 9 and the second honeycomb porous air cavity 6 have the same structure.

[0078] As an optional implementation, the displacement sensor includes:

[0079] The linear variable differential transformer 4 has a fixed end fixedly connected to the top of the inner grouting tube 8, and a movable end of the linear variable differential transformer 4 fixedly connected to the pressure end of the pressure device.

[0080] As an optional embodiment, the pressure applying device includes:

[0081] The axial displacement control device 1, the base 13 is placed in the axial displacement control device 1, and the movable end of the axial displacement control device 1 is fixedly connected to the top of the piston 2;

[0082] The active end of the linear variable differential transformer 4 is fixedly connected to the active end of the axial displacement control device 1 .

[0083] The data acquisition system includes a data acquisition device and a computer. One end of the data acquisition device is electrically connected to the flow meter, pressure gauge, linear variable differential transformer 4 and axial displacement control device 1 of the entire test system, and the other end is connected to the computer.

[0084] The mining fractured rock mass grouting test method with real-time synchronous permeability measurement is based on the above-mentioned mining fractured rock mass grouting test device with real-time synchronous permeability measurement, and comprises the following steps:

[0085] Fill the chamber with the sample and control the piston 2 to contact with the sample;

[0086] The pressure end of the pressure device is driven to drive the piston 2 to press the sample downward, adjust the porosity of the sample, and detect the displacement of the pressure end of the pressure device through the displacement sensor;

[0087] After reaching the target initial porosity, the pressure is released to a stable value and the loading pressure at the pressure end of the pressure applying device is kept constant, and the gas source and the grouting mechanism are turned on to inject grout into the chamber to start the seepage grouting test;

[0088] Controlling the grouting part to inject slurry into the grouting mechanism so that the slurry is injected into the chamber;

[0089] Connecting the gas source to the gas inlet portion, and controlling the gas source to inject high-pressure gas into the chamber through the gas inlet portion;

[0090] Connecting the gas collecting device to the exhaust section;

[0091] Acquiring intake pressure data based on the intake amount of the intake part;

[0092] acquiring exhaust pressure data based on the exhaust volume of the exhaust section;

[0093] Obtain grouting pressure data of the grouting department;

[0094] The permeability and nonlinear seepage factor are obtained based on the air intake volume, air intake pressure data, exhaust volume, exhaust pressure data and grouting pressure data.

[0095] Embodiment 2:

[0096] refer to Figure 4 This embodiment is a process of obtaining permeability using the device and method of embodiment 1:

[0097] Step 1, setting the particle size range and continuous grading conditions of the sample and loading the rock sample, calculating the mass of crushed stones of different particle sizes according to the Talbot grading method, weighing and loading them into the chamber, placing a piston 2 above the chamber, i.e., the sample, and making the piston 2 contact with the pressure end of the axial displacement control device 1;

[0098] Step 2, connect the pipeline;

[0099] Step 3, install the data acquisition equipment such as flow meter and pressure meter for detecting the air intake volume, air intake pressure, exhaust volume, exhaust pressure and grouting pressure data;

[0100] Step 4, adjusting the porosity of the sample: installing a linear variable differential transformer 4 on the test device, starting the axial displacement control device 1 to load the piston 2, and controlling the height of the sample to adjust the porosity of the sample.

[0101] The porosity calculation process is as follows:

[0102] Initial porosity φ after axial pressure loading 0 The calculation formula is as follows:

[0103]

[0104] Among them, V 0 V is the volume of the rock sample in its natural state after axial pressure loading; S It is the absolute dense volume of the rock sample.

[0105] Absolute dense volume of rock sample V S The calculation formula is as follows:

[0106]

[0107] Among them, m s is the mass of the rock sample, ρ s is the mass density of the rock sample.

[0108] The height of the rock sample is h m :

[0109] h m =H 1 +H 2 -H 3 -H 4 -H 5 -H 6

[0110] Among them, H 1 H is the measured data of the linear variable differential transformer 4; 2 H is the height of the inner grouting tube 8; 3 Height of piston 2; H 4 H is the height of the second honeycomb porous cavity 6; 5 H is the height of the first honeycomb porous cavity 9; 6 is the height of the breathable gauze. 1 , H 2 , H 3 , H 4 , H 5 , H 6 All are known or measurable, the height H of the breathable gauze 6 Compared with other values, it is small and can be ignored. Start the axial displacement control device 1 to load the piston 2, the sample moves downward by Δh, and the linear variable differential transformer 4 measures the data H 1 changes have occurred.

[0111] From the above, we can know that the volume V of the rock sample in the natural state after axial pressure loading is 0 The calculation formula is as follows:

[0112] V 0 =πr 2 h m

[0113] Among them, r is the bottom radius of the inner grouting cylinder; h m is the height of the rock sample after axial pressure loading.

[0114] Then the initial porosity after axial pressure loading is 0 The revised calculation formula is as follows:

[0115]

[0116] Step 5, start the seepage grouting test:

[0117] First, open the gas injection pipeline, keep the axial loading pressure unchanged, open the gas valve of the high-pressure nitrogen tank in the gas injection pipeline, and adjust the gas injection pressure by connecting it to the pressure reducing valve, and adjust the pressure reducing valve until the gas pressure is stable;

[0118] Subsequently, the grouting pipeline is opened, and a pressure reducing valve is set between the pressure stabilizing tank and the grouting tank. During the preparation stage, the pressure reducing valve between the pressure stabilizing tank and the grouting tank and the exhaust valve of the pressure stabilizing tank are closed, the air inlet valve of the pressure stabilizing tank is opened, the air pump is turned on until the pressure in the pressure stabilizing tank reaches the set pressure, the air pump is turned off, and then the air inlet valve is closed, the pressure reducing valve and the mud valve are opened, and high-pressure gas is transported from the pressure stabilizing tank to the grouting tank, and the slurry is squeezed into the chamber through the mud valve. The grouting pressure is kept constant by adjusting the pressure reducing valve and the mud valve.

[0119] Measure the changes in slurry flow and gas flow during the grouting process; during this process, the flow meters set at the grouting port and air inlet in the chamber, and the pressure sensors set at the air inlet and air outlet respectively monitor the slurry flow, air inlet flow, air inlet gas pressure, and air outlet gas pressure and feed the data back to the data collector;

[0120] After grouting begins, the porosity calculation formula of the rock sample is:

[0121]

[0122] Among them, V 0 V is the volume of the rock sample in its natural state after axial pressure loading; S is the absolute dense volume of the rock sample; V r is the volume of slurry injected into the rock sample.

[0123] The volume of slurry injected into the rock sample V r It can be obtained according to the flow meter at the grouting port, satisfying the following relationship:

[0124]

[0125] in, T i The accumulated flow rate of the slurry pipeline at that moment.

[0126] According to the measured gas flow data, the flow rate of the seepage gas can be calculated as:

[0127]

[0128] in, is the gas pipeline flow at the air inlet; r is the bottom radius of the inner grouting tube; ν is the seepage gas flow rate.

[0129] According to Forchheimer theory, the fluid in the rock sample satisfies:

[0130]

[0131] Wherein, μ is the fluid dynamic viscosity coefficient; k is the permeability of the mining fractured rock mass; β is the non-Darcy factor; ρ ω is the fluid density; υ is the fluid velocity; p is the fluid pressure.

[0132] Based on a large number of test and simulation results, the empirical formula of non-Darcy factor is as follows:

[0133]

[0134] According to the test measurement data:

[0135] -Δp=p in -p out

[0136] Among them, p in is the gas pressure at the air inlet; p out is the gas pressure at the outlet.

[0137] The corrected permeability calculation formula is:

[0138]

[0139] Among them, p in is the gas pressure at the air inlet; p out is the gas pressure at the outlet; ρ ω is the fluid density; m s is the mass of the rock sample, ρ s is the mass density of the rock sample; is the gas pipeline flow rate at the air inlet; r is the bottom radius of the inner grouting tube; h m is the height of the rock sample after axial pressure loading; T i The accumulated flow rate of the slurry pipeline at that moment.

[0140] After the test is completed, close the mud valve and pressure reducing valve, open the exhaust valve to exhaust the gas in the stabilization tank, clean the grouting tank, and complete the test.

[0141] Step 6, data analysis: The computer obtains the data stored in the recorder, and uploads the data such as the gas pipeline flow at the air inlet, the gas pressure at the inlet and the outlet, and the cumulative flow of the slurry pipeline to the computer. After analyzing and processing the data, the permeability of the mined fractured rock mass at different times under grouting conditions is finally obtained.

[0142] Embodiment 3:

[0143] According to the permeability calculation process of Example 2, we provide a specific application example, selecting red sandstone as the rock sample for testing, crushing it into particles by a rock crusher and screening it with a sieve, and the particle size is selected as particle size 1 (0-5mm), particle size 2 (5-10mm), particle size 3 (10-15mm), particle size 4 (15-20mm), and particle size 5 (20-25mm). Set the Talbot index to 1, and according to the Talbot index characterizing the particle size distribution, take 1200g of red sandstone of different particle sizes for mixing, and then load the axial load to adjust the porosity of the sample, set the initial porosity of the sample to 0.183, and the height of the sample to 130mm. After starting the seepage grouting test, keep the axial loading pressure at 3MPa; open the high-pressure nitrogen tank, and adjust the pressure reducing valve to a stable pressure of 0.3MPa and then control the gas pressure to remain unchanged; close the pressure reducing valve and the exhaust valve, open the air inlet valve, and start the air pump until the pressure in the pressure regulating tank reaches the set pressure, and then turn off the air pump; close the air inlet valve, open the pressure reducing valve and the mud valve, and transport high-pressure gas from the pressure regulating tank to the grouting tank, and control the grouting pressure to a stable value of 1MPa by adjusting the air inlet valve and the mud valve, and then control the grouting pressure to remain unchanged.

[0144] By measuring the changes in slurry flow and gas flow during the grouting process; in this process, the flow meters at the grouting port and the air inlet, and the pressure sensors at the grouting port, the air inlet and the air outlet respectively monitor the slurry flow, air inlet flow, air inlet gas pressure, and air outlet gas pressure and feed them back to the data collector, and the computer processes the data to obtain the following: Figure 4 The permeability change line graph is shown.

[0145] Embodiment 4:

[0146] This embodiment is a process of obtaining a nonlinear seepage factor using the apparatus and method of embodiment 1: The fluid in the rock sample obtained in combination with embodiment 2 satisfies the relationship:

[0147]

[0148] On this basis, the nonlinear seepage factor is defined to satisfy the following relationship:

[0149]

[0150] Wherein, μ is the fluid dynamic viscosity coefficient; k is the permeability of the mining fractured rock mass; β is the non-Darcy factor; ρ ω is the fluid density; υ is the fluid velocity; p is the fluid pressure.

[0151] Substituting the non-Darcy factor empirical formula and porosity formula into the formula, the corrected nonlinear seepage factor can be obtained as follows:

[0152]

[0153] Among them, ρ ω is the fluid density; m s is the mass of the rock sample; ρ s is the mass density of the rock sample; is the gas pipeline flow rate at the air inlet; r is the bottom radius of the inner grouting tube; h m is the height of the rock sample after axial pressure loading; T i The cumulative flow rate of the slurry pipeline at the moment; μ is the dynamic viscosity coefficient of the fluid.

[0154] Embodiment 5:

[0155] According to the calculation process of the nonlinear seepage factor of Example 4, we provide a specific application example, selecting red sandstone as the rock sample for testing, crushing it into particles by a rock crusher and screening it with a sieve, and the particle size selected is particle size 1 (0-5mm), particle size 2 (5-10mm), particle size 3 (10-15mm), particle size 4 (15-20mm), and particle size 5 (20-25mm). Set the Talbot index to 1, and according to the Talbot index characterizing the particle size distribution, take 1200g of red sandstone of different particle sizes for mixing, and then load the axial load to adjust the porosity of the sample, set the initial porosity of the sample to 0.242, and the height of the sample to 140mm. After starting the seepage grouting test, keep the axial loading pressure at 3MPa; open the high-pressure nitrogen tank, and adjust the pressure reducing valve to a stable pressure of 0.3MPa and then control the gas pressure to remain unchanged; close the pressure reducing valve and the exhaust valve, open the air inlet valve, and start the air pump until the pressure in the pressure regulating tank reaches the set pressure, and then turn off the air pump; close the air inlet valve, open the pressure reducing valve and the mud valve, and transport high-pressure gas from the pressure regulating tank to the grouting tank, and control the grouting pressure to a stable value of 2MPa by adjusting the air inlet valve and the mud valve, and then control the grouting pressure to remain unchanged.

[0156] By measuring the changes in slurry flow and gas flow during the grouting process; in this process, the flow meters at the grouting port and the air inlet, and the pressure sensors at the grouting port, the air inlet and the air outlet respectively monitor the slurry flow, air inlet flow, air inlet gas pressure, and air outlet gas pressure and feed them back to the data collector, and the computer processes the data to obtain the following: Figure 5 The line graph of nonlinear seepage factor change is shown.

[0157] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0158] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A mining fracture rock mass grouting test device for real-time synchronous permeability measurement, characterized in that: include: A base (13) is placed in the pressure-applying device, wherein the base (13) is provided with a chamber for storing a sample; An air inlet portion is arranged at the bottom of the chamber, an exhaust end of the air inlet portion contacts the bottom of the sample, an air inlet end of the air inlet portion is located outside the base (13), and the air inlet portion is used to communicate with a gas source and inject high-pressure gas into the chamber; An exhaust portion is arranged at the top of the chamber, an air inlet end of the exhaust portion contacts the top of the sample, the exhaust portion is arranged in the piston (2), the piston (2) is slidably arranged in the chamber, the exhaust end of the exhaust portion is located outside the piston (2), and the top of the piston (2) is mounted on the pressure end of the pressure device; A grouting part, wrapped around the side wall of the sample, the bottom of the grouting part is fixedly connected to the base (13), and the liquid outlet end of the grouting part is connected to the chamber, and is used to inject slurry into the chamber; The displacement sensor is used to detect the height of the piston (2) exceeding the top of the chamber to obtain the height of the sample.

2. The mining fracture rock mass grouting test device for real-time synchronous permeability measurement according to claim 1 is characterized in that: The grouting unit comprises: An inner grouting tube (8), the bottom of the inner grouting tube (8) is axially connected to the base (13), the chamber is arranged in the inner grouting tube (8), and a plurality of grouting holes for communicating with the chamber are evenly opened on the side wall of the inner grouting tube (8); The outer cylinder (7) is coaxially arranged outside the inner grouting cylinder (8), the bottom of the outer cylinder (7) is fixedly connected to the top of the base (13), and the top of the outer cylinder (7) is fixedly connected to the top of the inner grouting cylinder (8); The inner wall of the outer cylinder (7) and the outer wall of the inner grouting cylinder (8) together form a slurry temporary storage cavity, and the slurry temporary storage cavity is connected to the liquid inlet ends of the plurality of grouting holes; The slurry temporary storage chamber is connected to a grouting port (10), and the grouting port (10) is opened on the outer cylinder (7).

3. The mining fracture rock mass grouting test device for real-time synchronous permeability measurement according to claim 1 is characterized in that: The air intake portion comprises: A first honeycomb-shaped porous air cavity (9) is arranged at the bottom of the chamber, an air inlet end of the first honeycomb-shaped porous air cavity (9) is connected to an exhaust end of an air inlet pipeline, the air inlet pipeline is buried in the base (13), an air inlet port (12) of the air inlet pipeline is arranged on a side wall of the base (13), and the air inlet port (12) is used to connect to an air source; A breathable gauze (14) is laid between the exhaust end of the first honeycomb porous air cavity (9) and the sample.

4. The mining fracture rock mass grouting test device for real-time synchronous permeability measurement according to claim 1 is characterized in that: The exhaust section comprises: The second honeycomb porous air cavity (6) is slidably arranged in the chamber, the second honeycomb porous air cavity (6) is fixedly connected to the bottom of the piston (2), the air inlet end of the second honeycomb porous air cavity (6) is in contact with and connected to the top of the sample, the air outlet end of the second honeycomb porous air cavity (6) is connected to the air inlet end of the exhaust pipeline, the exhaust pipeline is buried in the piston (2), and the air outlet (3) of the exhaust pipeline is opened on the side wall of the piston (2).

5. The mining fracture rock mass grouting test device for real-time synchronous permeability measurement according to claim 2 is characterized in that: The displacement sensor comprises: A linear variable differential transformer (4), wherein the fixed end of the linear variable differential transformer (4) is fixedly connected to the top of the inner grouting tube (8), and the movable end of the linear variable differential transformer (4) is fixedly connected to the pressure end of the pressure device.

6. The mining fracture rock mass grouting test device for real-time synchronous permeability measurement according to claim 5 is characterized in that: The pressure applying device comprises: An axial displacement control device (1), wherein the base (13) is placed inside the axial displacement control device (1), and the movable end of the axial displacement control device (1) is fixedly connected to the top of the piston (2); The active end of the linear variable differential transformer (4) is fixedly connected to the active end of the axial displacement control device (1).

7. A grouting test method for mining fractured rock mass with real-time synchronous permeability measurement, according to the grouting test device for mining fractured rock mass with real-time synchronous permeability measurement according to any one of claims 1 to 6, characterized in that: The steps include: Filling the sample into the chamber and controlling the piston (2) to contact the sample; The pressure end of the pressure device is driven to drive the piston (2) to press the sample downward, thereby adjusting the porosity of the sample, and detecting the displacement of the pressure end of the pressure device through a displacement sensor; After reaching the target initial porosity, the pressure is released to a stable value and the loading pressure at the pressure end of the pressure applying device is kept constant, and the gas source and the grouting mechanism are turned on to inject grout into the chamber to start the seepage grouting test; Controlling the grouting part to inject slurry into the grouting mechanism so that the slurry is injected into the chamber; Connecting a gas source to the gas inlet portion, and controlling the gas source to inject high-pressure gas into the chamber through the gas inlet portion; Connecting a gas collecting device to the exhaust portion; acquiring intake pressure data based on the intake amount of the intake portion; acquiring exhaust pressure data based on the exhaust volume of the exhaust portion; Acquiring grouting pressure data of the grouting part; The permeability and nonlinear seepage factor are obtained based on the air intake volume, air intake pressure data, exhaust volume, exhaust pressure data, and grouting pressure data.

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