CN105866004A - Device and method for measuring permeability coefficient of rock - Google Patents

Abstract

The invention relates to lateral seepage of rock, particularly to a device for measuring the permeability coefficient of rock. The device comprises a test piece device system, an axial loading system, a confining pressure system, a gas pressure loading system, a servo control system and a computer controller, wherein the test piece device system comprises a rock test piece, an upper rigid pressing plate, a lower rigid pressing plate, a rubber sleeve and a circular button; three hollow triggers are respectively arranged on each of the left and right sides of the rubber sleeve and are positively opposite; the gas pressure loading system is provided with hollow steel pipes capable of being inserted into the hollow triggers on the two sides of the rubber sleeve; the three steel pipes at an inlet are provided with control valves for controlling to let gas to flow through the steel pipes or not; after being inserted into the hollow triggers of the rubber sleeve, the steel pipes are tightened with the circular button, so as to prevent the gas from escaping from the contact positions of the steel pipes and the rubber sleeve. A stable state method is adopted in a test to measure the permeability coefficient of the rock.

Description

A device and method for measuring rock permeability coefficient

technical field

The invention relates to the technical fields of engineering geology such as rock soil and mining, and in particular to a seepage device and a test method for measuring rock permeability coefficient through rock lateral seepage.

Background technique

Fractured rock mass is a complex medium often encountered in various projects such as water conservancy and hydropower projects, mining projects, railway and highway construction projects, civil construction projects, petroleum engineering, marine exploration and development projects, and the determination of the seepage coefficient of rock fractures is always a rock Frontiers and hot topics of research by mechanics workers.

In existing technologies and devices, no matter whether the rock permeability coefficient is measured by the steady-state method or the transient method, a seepage pressure difference is formed between the upper and lower ends of the rock specimen, and the fluid penetrates from the high-pressure end through the rock medium to the low-pressure end. , to calculate the rock permeability coefficient. However, rock is not a homogeneous medium, and its permeability coefficient is not only related to the composition and structure of the rock, but also the permeability coefficient of the rock is different in different infiltration directions. Secondly, the fluid used in most experiments is liquid (water). When the liquid passes through the channel, the liquid molecules in the center of the channel have a higher flow rate than those near the surface of the channel wall. That is the Klinkenberg effect. For the fluid selection and seepage direction in the rock permeability coefficient measurement device, most of the existing technologies are aimed at using water as the seepage medium, and at the same time flowing from one end face with high water pressure to the other end face with low water pressure, that is, axial seepage. There is no seepage device and test method for measuring rock permeability coefficient by using gas to carry out rock lateral flow.

Contents of the invention

In order to solve the above technical problems, the present invention provides a seepage device and test method for measuring rock permeability coefficient by measuring rock direction seepage. At the same time, gas (nitrogen) is used as the seepage medium to measure lateral seepage while avoiding the Klinkenberg effect. Rock permeability coefficient.

In order to achieve the above purpose, the patent of the present invention adopts the following solution: a seepage device for measuring rock permeability coefficient by rock lateral seepage, including a test piece device system, an axial loading system, a confining pressure system, a gas pressure loading system, and a servo control system and a computer controller, the test piece device system includes a rock test piece, upper and lower rigid platens and three hollow tentacles on both sides, transparent rubber sleeves with good elasticity, ring buttons, the upper and lower rigid pressure plates The pressure plates are in the opposite position and have the same shape; the bottom of the upper rigid pressure plate faces upwards, and the top is buckled upside down on the top of the rock specimen; The hollow tentacles on both sides of the sleeve are also in the opposite position; the gas pressure loading system is provided with hollow steel pipes that can be inserted into the hollow tentacles on both sides of the rubber sleeve, and the three steel pipes at the air inlet are equipped with control valves to control whether the gas flows The steel pipe flows through; the steel pipe is inserted into the hollow tentacles of the rubber sleeve and fastened with a ring button to prevent the gas from escaping from the contact between the steel pipe and the rubber sleeve. Barometers are installed at the inlet and outlet steel pipes; the test adopts the steady state method to measure the rock permeability coefficient .

The beneficial effect that the present invention produces relative to prior art is:

1. Use gas (nitrogen) as the seepage medium to avoid the slippage effect caused by using liquid as the seepage medium.

2. The seepage direction is lateral seepage, that is, it flows from one side of the rock to the other side. In the past, the seepage direction all flows from one end face of the rock to the other end face. The rock permeability coefficient measured by the present invention also illustrates the rock's permeability from another angle. anisotropy.

3. It is simple to manufacture and easy to install, providing convenience for scientific research.

In short, the technical solution of the present invention lies in: (1) Using gas as the seepage medium avoids the slipping effect caused by using liquid (such as pure water) as the seepage medium. (2) The seepage direction used in the present invention is seepage from one side of the rock to the other side. The different rock permeability coefficients measured by two different seepage directions under the same stress state illustrate the anisotropy of rock permeability coefficient from another angle. This is where the outstanding advantages and advantages of the present invention lie, and also its main innovation point.

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

Description of drawings

Fig. 1 is a schematic diagram of the structure of a seepage device for measuring rock permeability coefficient by rock lateral seepage according to the present invention

Fig. 2 is a sectional view of the test piece system of the present invention

Figure 3 shows the relationship between different osmotic pressure differences and permeability coefficients

In the figure: 1. Loading oil cylinder, 2. Servo motor, 3. Reducer, 4. Screw transmission pair, 5. Piston, 6. Confining pressure sensor, 7. Rubber sleeve, 8. Hollow antenna on the left side of rubber sleeve, 9. Ring button on the left side, 10, hollow antennae on the right side of the rubber sleeve, 11, radial displacement extensometer, 12, axial displacement extensometer, 13, upper rigid pressure plate, 14, lower rigid pressure plate, 15, pressure bearing plate, 16. Base, 17. Pneumatic cylinder, 18. Flow sensor I, 19. Barometer I, 20. Barometer II, 21. Flow sensor II, 22. Air storage cylinder, 23. Axial force sensor, 24. Loading shaft, 25 , Rock specimen, 26, triaxial cavity, 27, data line I, 28, data line II, 29, data line III, 30, data line IV, 31, data line V, 32, data line VI, 33, valve I, 34, valve II, 35, valve III, 36, valve IV, 37, valve V, 38, valve VI, 39, valve VII, 40, right ring button, 41, computer controller, 42, heating ring, 43. Temperature sensor, 44. Data line VII, 45. Rigid spacer, 46. Layered joint surface.

detailed description

Referring to accompanying drawing 1, a kind of rock lateral seepage measurement rock permeability coefficient test device, comprises test piece device system, axial force loading system, confining pressure system, gas pressure loading system, servo control system and computer controller, described test piece device The system includes a rock specimen 25, an upper rigid pressure plate 13, a lower rigid pressure plate 14, a transparent and elastic rubber sleeve 7, three hollow tentacles 8 on the left side of the rubber sleeve, three hollow antennae 10 on the right side of the rubber sleeve, The left ring button 9, the right ring button 40, the upper rigid pressure plate 13 and the lower rigid pressure plate 14 are in the opposite position and have the same shape; 25 top, the bottom of the lower rigid pressure plate 14 is downwards, and the top is supported on the bottom of the rock specimen 25; the hollow tentacles 8 and 10 on both sides of the rubber sleeve 7 are also in the opposite position; the gas pressure loading system is provided with Hollow steel pipes that can be inserted into the hollow tentacles 8 and 10 on both sides of the rubber sleeve 7, the three steel pipes at the air inlet are provided with control valves 34, 35, 36 to control whether the gas flows through the steel pipes; the steel pipes are inserted into the rubber sleeve 7 The hollow tentacles 8 and 10 are fastened with ring buttons 9 and 40 to prevent gas from escaping from the contact between the steel pipe and the rubber sleeve 7. The air inlet and outlet steel pipes are equipped with barometer I19, barometer II20, flow sensor I18 and flow rate Sensor II21; the end face of the steel pipe inserted into the hollow antennae 8 on the left side of the rubber sleeve is arc-shaped to ensure that the steel pipe and the rock test piece 25 fit perfectly. The steady-state method was used to measure the rock permeability coefficient in the test.

The test piece device system comprises a cylindrical rubber sleeve 7 with transparent hollow tentacles, a rock test piece 25, ring buttons 9 and 40, a rigid spacer 45, and the rock test piece 25 is a horizontal layered rock and its layered joint surface is 46. As shown in accompanying drawing 1, put it between the upper rigid platen 13 and the lower rigid platen 14 after the rock test piece 25 is covered with rubber sleeve 7, and place it on the rigid pad 45 as a whole.

The axial pressure loading system includes an axial force sensor 23 , a loading shaft 24 , a triaxial chamber 26 , a pressure bearing plate 15 and a base 16 . Load and unload the axial stress on the rock specimen 25 through the up and down movement of the loading shaft 24, the axial force sensor 23 on the loading shaft 24 detects the magnitude of the axial force and transmits it to the computer controller 41, and the loading shaft 24 acts on The upper rigid pressure plate 13 applies an axial force to the rock specimen 25 through the upper rigid pressure plate 13 .

The confining pressure system includes a triaxial self-balancing pressure chamber and a confining pressure loading system. The specimen device system is placed in a triaxial self-balancing pressure chamber, which is connected to the confining pressure loading system through oil pipes, and its function is to apply confining pressure to the rock specimen 25, and the confining pressure is loaded through the loading cylinder 1. Realize that the servo motor 2 rotates according to the instructions issued by the test software and drives the piston 5 to move linearly through the speed reducer 3 to drive the movement of the screw transmission pair 4 to adjust the pressure in the oil cylinder. The confining pressure sensor 6 installed at the oil outlet end of the loading cylinder 1 detects the oil pressure , sent to the computer controller 41, the computer controller 41 processes the pressure measurement signal, compares it with the set pressure data, and then gives a correction signal, so that the applied pressure value tends to be consistent with the set pressure value.

The pneumatic cylinder 17 in the gas pressure system can change the gas pressure at any time, the flow sensor I18 can record the gas flow in real time, and the air pressure of the seepage air inlet can be adjusted through the pneumatic cylinder 17. The gas seeps into the layered joint surface 46 of the rock specimen 25 through the steel pipes of the three hollow tentacles 8 on the left side of the rubber sleeve 7 inserted into the test piece device system, and passes through the three right sides of the rubber sleeve 7 inserted into the test piece device system. The steel pipe of hollow tentacles 10 enters air storage cylinder 22. Barometer I19 and barometer II20 monitor the gas pressure at the inlet and outlet in real time, and the gas flow sensor I18 and gas flow sensor II21 record the gas flow at the inlet and outlet in real time and feed it back to the computer controller 41 .

The temperature system includes a heating coil 42 and a temperature sensor 43 . The heating ring 42 heats the wall surface of the triaxial cavity 26 and utilizes heat conduction to heat the temperature of the silicone oil (liquid used for applying confining pressure) in the triaxial cavity, thereby heating the test piece. The temperature in the three-axis chamber 26 is detected in real time by the temperature sensor 43, and is fed back to the computer controller 41 to give instructions to the software for the next step.

The data collection system includes collection of data such as gas flow and pressure, axial deformation and radial deformation of the rock test piece 25, confining pressure and axial pressure, confining pressure temperature, etc. The flow sensor I18 and the computer controller 41 of the gas pressure loading system connected to collect gas flow data in real time; the axial displacement extensometer 12 and the radial displacement extensometer 11 are connected to the computer controller 41 to collect the axial deformation data and radial deformation data of the rock specimen 25 in real time; The axial force sensor 23 of the system is connected to the computer controller 41 to collect axial pressure data in real time; the confining pressure sensor 6 of the confining pressure system is connected to the computer controller 41 to collect confining pressure data in real time; the temperature sensor 43 is connected to the computer controller 41 Connected to collect temperature change data during the test in real time. During the test, the computer records the gas flow rate, the axial deformation and radial deformation of the rock test piece 25, the confining pressure and the axial pressure in real time.

An embodiment of an experimental device for measuring rock permeability coefficient by rock lateral seepage in the present invention:

(1) The rock block is processed and polished to make a rock sample specimen 25. The size of the rock specimen 25 is 50 mm in diameter and 100 mm in height. The rubber sleeve 7 with a diameter of 45 mm and a length of 110 mm is used to cover the specimen 25. The rock test piece 25 of the upper rubber sleeve 7 is placed on the top of the lower rigid pressure plate 14, and then the upper rigid pressure plate 13 is buckled upside down on the upper end surface of the rock test piece 25, and finally the whole is placed on the rigid spacer 45. Insert the hollow tentacles 8 and 10 on the left and right sides of the rubber sleeve 7 of the 25 overcoat, and fasten them with ring buttons 9 and 40. A radial displacement sensor 11 is installed in the middle to measure the radial deformation of the rock sample 25. The lower rigid pressure plates 13 and 14 are provided with axial displacement sensors 12 to measure the axial deformation of the rock sample specimen 25, and the radial displacement extensometer 11 and the axial displacement extensometer 12 are respectively passed through the data line I27, data line II28 and Computer controller 41 is connected.

(2) Connect the pipelines of the confining pressure system, the gas pressure loading system and the confining pressure temperature control system, the gas at the gas outlet is stored in the gas storage cylinder 22, the axial force sensor 23, the temperature sensor 43, the flow sensor I18, and the flow sensor II21 , the axial displacement extensometer 12, the radial displacement extensometer 11, and the confining pressure sensor 6 are connected to the computer controller 41 respectively.

(3) Load and unload the axial stress on the rock specimen 25 through the up and down movement of the loading shaft 24. The axial force sensor 23 on the loading shaft 24 detects the magnitude of the axial force and transmits it to the computer controller 41. 24 acts on the upper rigid platen 13 to apply axial force to the rock specimen 25. When the oil source of the loading cylinder 1 is sufficient in the confining pressure loading system, the valve VII39 is opened, and the confining pressure is applied to the rock specimen 25 through the linear motion of the piston 5 .

(4) Close the valve VII39 after completing the above steps. When the gas in the pneumatic cylinder 17 is sufficient, close the valve I33 and measure the temperature in the triaxial chamber 26 through the temperature sensor 43. When the pressure and temperature in the chamber reach the design value, and when the air pressure gauge When the value of I19 reaches the preset value, valve I33 and valve V37 are opened, and valve II34, valve III35 and valve IV36 are selectively opened to realize gas seepage. Cylinder 22, barometer I19 and barometer II20 detect the gas pressure P _in and P _{out of the} air inlet and outlet respectively, and the computer controller 41 records the flow Q flowing through the rock test piece 25, and the rock permeability coefficient is calculated by the following formula Among them, L is 50 mm, and A is 0.005 mm ² .

Let's further illustrate with an example:

The selected sample is Maokou Limestone of Coal Dam in Ningxiang, Hunan Province. The weight of the sample is 423.89g, the diameter is _49.95mm , and the length is _101.03mm . The seepage medium is nitrogen. In this case, the effect of different seepage pressure differences p on the rock permeability coefficient k is studied (see Table 1), and the obtained test results are processed with Origin (see Figure 3).

It can be seen from Fig. 3 that when the stress state of the specimen remains unchanged, that is, the axial pressure σ ₁ and the confining pressure σ ₂ remain unchanged, the permeability coefficient k of the rock increases with the increase of the seepage pressure difference p.

Table 1: Effects of different seepage pressure differences p on rock permeability coefficient k

Axial pressure σ ₁ /MPa Confining pressure σ ₂ /MPa Osmotic pressure difference p/MPa Permeability coefficient k/(10 ^-9 m/s) 8 5 2 7.68 8 5 3 7.94 8 5 4 8.32

Claims (6)

1. the horizontal seepage flow of rock measures rock permeability ratio test device, it is characterised in that include examination Part apparatus system, axle force loading system, confined pressure system, gas pressure loading system, servo-control system and Computer controller.

Experimental rig the most according to claim 1, it is characterised in that described specimen appliance system includes Rock sample (25), upper rigidity platen (13), lower rigidity platen (14), transparence and there is favorable elasticity Rubber sleeve (7), the hollow feeler in the left side (8) of rubber sleeve (7), rubber sleeve (7) right side hollow touch Angle (10), left side annular button (9), right circular button (40), described upper rigidity platen (13) with Lower rigidity platen (14) is identical to position and shape in positive；Upper rigidity platen (13) is bottom-up, top Portion tips upside down on downwards rock sample (25) top, the bottom of lower rigidity platen (14) downwards, top upwards It is supported on the bottom of rock sample (25)；The hollow feeler (8) of described rubber sleeve (7) two side and (10) Also in positive to position.

Experimental rig the most according to claim 1, it is characterised in that described gas pressure loading system Being provided with the hollow steel pipe that can be inserted into the hollow feeler in rubber sleeve (7) both sides, the steel pipe of air inlet is equipped with control Valve, is used for controlling whether gas flows through from steel pipe；Ring is used after the hollow feeler of steel pipe insertion rubber sleeve (7) Shape button (9) and (40) buckle, and prevent gas from escaping from the contact position of steel pipe and rubber sleeve (7), enter, Give vent to anger be equipped with at steel pipe air gauge I (19), air pressure Table II (20) and flow sensor I (18) and Flow sensor II (21)；The Steel pipe end surface of the hollow feeler inserting rubber sleeve (7) is arc, it is ensured that steel Pipe and the perfect laminating of rock sample (25).

Experimental rig the most according to claim 1, it is characterised in that use steady state method to measure rock and ooze Coefficient thoroughly.

Experimental rig the most according to claim 1, it is characterised in that cylindrical rock sample (25) Size be 50mm × 100mm, and there is horizontal layer joint plane (46).

Experimental rig the most according to claim 1, it is characterised in that Gas seepage medium used is Nitrogen.