A permeability coefficient measuring device and method

Abstract

The application discloses a kind of permeability coefficient measuring device and method, belong to permeability coefficient measurement technical field.Permeability coefficient measuring device includes water head buried depth measuring device, drill pipe, water pressure device, pressure gauge, water connector, filter, first packer, second packer and controller;Drill pipe is connected after passing through first packer and filter, filter and second packer are connected, first packer and second packer are closed as test section between first packer and second packer;Water head buried depth measuring device includes host computer, electrode converter and multiple electrodes, host computer is connected with electrode converter and controller signal respectively, electrode converter is electrically connected with each electrode respectively, and water head buried depth measuring device is used to measure the electrode water head buried depth and drill hole water head buried depth of each electrode by high-density electrical method;Controller is used to receive electrode water head buried depth, drill hole water head buried depth and water pressure flow and calculate permeability coefficient accordingly.The application is accurate to measure multi-scale permeability coefficient by multiple different direction electrodes and water pressure device cooperation data acquisition.

Description

Technical Field

[0001] This invention relates to a device and method for measuring permeability coefficient, belonging to the field of permeability coefficient measurement technology. Background Technology

[0002] Seepage in rock masses primarily occurs at structural planes and within their fracture networks. The heterogeneity and anisotropy of seepage in fractured rock masses are mainly caused by differences in lithology and the block differences among broken rock fragments. Rock mass seepage is a common concern in fields such as hydraulics, civil engineering, resources, and geology. Determining rock mass permeability plays a crucial role in hydraulic engineering, deep-buried tunnel excavation, and various hydrogeological explorations. Understanding the seepage patterns and determining seepage parameters of rock masses is key to achieving rock mass seepage analysis and control. By measuring the permeability of rock masses, controllable reference data can be provided for underground safe production, seepage prevention design in hydraulic and hydropower projects, and engineering construction.

[0003] The primary method for determining the permeability coefficient of rock masses in the current technology is field testing. Field tests include pressure water tests, pumping tests, and injection tests, with pressure water tests being the most widely used. Pressure water tests can effectively reflect the permeability characteristics of rock masses within a test section of approximately 10 meters. However, their effectiveness decreases when determining the permeability coefficient of rock masses at multiple or larger scales. Furthermore, the conversion between permeability and rock mass permeability coefficient obtained from pressure water tests is based on empirical formulas and cannot be directly calculated using the pressure water flow rate. The measurement process is complex, and obtaining the permeability coefficient often involves a pressure water test scheme with one test well and one observation well. The rock mass permeability coefficient is calculated by measuring the water level in the observation well, making it impossible to accurately measure the anisotropy of the permeability coefficient in different directions. Summary of the Invention

[0004] The purpose of this invention is to provide a permeability coefficient measuring device and method, which solves the problems of low effectiveness, complex measurement process, and inaccurate measurement of the anisotropy of permeability coefficient in various directions in the existing technology when measuring permeability coefficient at multiple or larger scales.

[0005] To achieve the above objectives, the present invention employs the following technical solution: In a first aspect, the present invention provides a permeability coefficient measuring device, including a water head burial depth measuring device, a drill rod, a water pressurizing device, a water supply tank, a pressure gauge, a water connector, a filter, a first packer, a second packer, and a controller; The drill rod is used to drill a borehole in the rock mass area to be tested and remains in the borehole. The drill rod has a hollow structure. After passing through the first packer, the drill rod connects to the filter. The filter connects to the second packer. The enclosed area between the first and second packers is the test section. The head depth measuring device includes a main unit, an electrode converter, and multiple electrodes. The main unit is connected to the electrode converter and the controller for signal transmission. The electrode converter is electrically connected to each electrode. The head depth measuring device is used to measure the electrode head depth and borehole head depth of each electrode using a high-density electrical resistivity tomography method. The water supply tank is used to supply water to the water pressure device. The water pressure device uses... The water connector connects to the drill rod, and the water pressurization device pressurizes water into the test section through the drill rod and measures the pressurized water flow rate at regular intervals. The water pressurization process includes multiple pressurization stages and multiple depressurization stages. During the pressurization or depressurization stages, the water pressurization device is also used to stop the water pressurization when the pressurized water flow rate meets the preset conditions, and the last pressurized water flow rate is used as the pressurized water flow rate of the current pressurization or depressurization stage. The controller is connected to the head depth measuring device and the water pressurization device respectively, and is used to receive the electrode head depth, borehole head depth and pressurized water flow rate of each electrode at each stage, and calculate the permeability coefficient of each electrode at each stage accordingly.

[0006] Furthermore, multiple electrodes are arranged horizontally and vertically on the ground surface around the borehole.

[0007] Furthermore, the water pressurization device includes an inlet pipe, a high-pressure water pump, a three-way flow regulating valve, a return pipe, a flow totalizer, a switch, a flow sensor, and a pressure valve; The inlet end of the inlet pipe is connected to the outlet of the water supply tank, the outlet end of the inlet pipe is connected to the inlet end of the high-pressure water pump, the first port of the three-way flow regulating valve is connected to the outlet end of the high-pressure water pump, the second port of the three-way flow regulating valve is connected to the inlet end of the return water pipe, the third port of the three-way flow regulating valve is connected in sequence to the switch, the flow sensor and the pressure valve, and the outlet end of the return water pipe is connected to the return water port of the water supply tank. The flow totalizer is electrically connected to the flow sensor and the controller respectively. It is used to receive the flow data transmitted from the flow sensor and calculate the pressurized water flow rate accordingly, and then transmit the pressurized water flow rate to the controller. The outlet end of the pressure valve is connected to the water connector.

[0008] Furthermore, the water pressurization process includes a first pressurization stage, a second pressurization stage, a third pressurization stage, a first depressurization stage, and a second depressurization stage. The water pressure relationship in each stage of the pressurization process is as follows: first pressurization stage < second pressurization stage < third pressurization stage, third pressurization stage > first depressurization stage > second depressurization stage.

[0009] Furthermore, stopping water pumping when the water flow rate meets a preset condition includes stopping water pumping when the water flow rate meets any one of the following conditions; Condition 1: The flow rate of water pressure in N consecutive tests is not less than 5 L / min, and the difference between the maximum and minimum values ​​is less than 10% of the flow rate of the last test. Condition 2: The flow rate of the water press is less than 5L / min for N consecutive times, and the difference between the maximum and minimum values ​​is less than 20% of the flow rate of the last water press. Condition 3: The flow rate of the pressurized water is less than 0.5 L / min for N consecutive times.

[0010] Furthermore, the permeability coefficient is calculated using the following formula: ; in, Indicates the first The permeability coefficient at each electrode position Indicates the water pressure flow rate. Represents the natural logarithm function. Indicates the drilling and the first The distance between the electrodes Indicates the borehole radius. Represents pi (π). Indicates the length of the test section. Indicates the depth of the borehole water head. Indicates the first The depth of the electrode head for each electrode.

[0011] Furthermore, it also includes a pressure gauge, which is installed on the water connector to monitor the test pressure. The test pressure is the sum of the pressure indicated by the pressure gauge and the water column pressure from the center of the pressure gauge to the zero line of the pressure calculation. After the test pressure stabilizes, the controller receives the electrode head depth, borehole head depth, and pressurized water flow rate of each electrode at each stage, and calculates the permeability coefficient of each electrode at each stage accordingly.

[0012] In a second aspect, the present invention provides a method for measuring permeability coefficient, implemented based on the permeability coefficient measuring device described in any one of the first aspects, comprising: Drill a borehole and install the permeability measuring device; Turn on the water pressurization device and start measuring the water pressurization flow rate at regular intervals after the test pressure stabilizes. Press water into the test section in the order of first executing the pressurization stage and then the depressurization stage. During the pressurization stage or the depressurization stage, stop the water pressurization when the water pressurization flow rate meets the preset conditions, and take the last water pressurization flow rate as the water pressurization flow rate of the current pressurization stage or the depressurization stage. The electrode head depth and borehole head depth of each electrode are measured using a head depth measuring device. Based on the electrode head depth, borehole head depth, and pressurized water flow rate at each stage, calculate the permeability coefficient of each electrode at each stage.

[0013] Furthermore, the permeability coefficient is calculated using the following formula: ; in, Indicates the first The permeability coefficient at each electrode position Indicates the water pressure flow rate. Represents the natural logarithm function. Indicates the drilling and the first The distance between the electrodes Indicates the borehole radius. Represents pi (π). Indicates the length of the test section. Indicates the depth of the borehole water head. Indicates the first The depth of the electrode head for each electrode.

[0014] Compared with the prior art, the beneficial effects achieved by the present invention are: This invention provides a permeability coefficient measuring device and method. By setting up multiple electrodes in the head depth measuring device, the electrode head depth of each electrode within different scale ranges from the borehole can be measured. In conjunction with a water pressure device, the permeability coefficient within a multi-scale range can be calculated based on the electrode head depth of each electrode and the water pressure flow rate at each stage. This enables the measurement of permeability coefficients at larger scales. Compared to the traditional water pressure test scheme of one test well and one observation well, this method is more effective in measuring permeability coefficients at multiple or larger scales. The results of the traditional water pressure test scheme of one test well and one observation well are significantly improved. The calculation is based on the assumption of isotropic permeability of the rock mass. However, natural rock mass seepage is anisotropic. This invention, through the setting of multiple electrodes in the water head burial depth measuring device, can deploy electrodes in different directions to accurately measure the different permeability coefficients in different directions caused by the anisotropy of rock mass seepage. In traditional methods, the permeability coefficient cannot be directly converted from the results of water pressure tests, that is, it cannot be directly calculated using water pressure flow rate. It can only calculate the reference value of the permeability coefficient through empirical formulas. However, this invention can directly calculate the permeability coefficient of the rock mass based on water pressure flow rate, electrode water head burial depth, and borehole water head burial depth, making the measurement more convenient.

[0015] By using high-density electrical resistivity tomography (EDT) to measure water levels instead of the traditional method of using observation wells, the operation difficulty is effectively reduced, the repeatability is high, and the results are intuitive and clear. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of a permeability measuring device provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of a portion of the device used to perform a pressure water test in a permeability coefficient measuring device provided in an embodiment of the present invention.

[0017] In the diagram: 1. Main unit; 2. Electrode converter; 3. Cable; 4. Electrode; 5. Water supply tank; 6. Water pressure device; 7. Water connector; 8. Drill hole; 9. Drill rod; 10. First packer; 11. Filter; 12. Inlet pipe; 13. Return pipe; 14. Three-way flow regulating valve; 15. High-pressure water pump; 16. Flow totalizer; 17. Switch; 18. Flow sensor; 19. Pressure valve; 20. High-pressure water pipe; 21. Pressure gauge; 22. Pressure measuring tube; 23. Second packer. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to illustrate the technical solution of the present invention more clearly, and should not be used to limit the scope of protection of the present invention.

[0019] Example 1

[0020] This embodiment provides a permeability coefficient measuring device, including a water head burial depth measuring device, a drill rod, a water pressurizing device, a water supply tank, a pressure gauge, a water connector, a filter, a first packer, a second packer, and a controller; The drill rod is used to drill a borehole in the rock mass area to be tested and remains in the borehole. The drill rod has a hollow structure. After passing through the first packer, the drill rod connects to the filter. The filter connects to the second packer. The enclosed area between the first and second packers is the test section. The head depth measuring device includes a main unit, an electrode converter, and multiple electrodes. The main unit is connected to the electrode converter and the controller for signal transmission. The electrode converter is electrically connected to each electrode. The head depth measuring device is used to measure the electrode head depth and borehole head depth of each electrode using a high-density electrical resistivity tomography method. The water supply tank is used to supply water to the water pressure device. The water pressure device uses... The water connector connects to the drill rod, and the water pressurization device pressurizes water into the test section through the drill rod and measures the pressurized water flow rate at regular intervals. The water pressurization process includes multiple pressurization stages and multiple depressurization stages. During the pressurization or depressurization stages, the water pressurization device is also used to stop the water pressurization when the pressurized water flow rate meets the preset conditions, and the last pressurized water flow rate is used as the pressurized water flow rate of the current pressurization or depressurization stage. The controller is connected to the head depth measuring device and the water pressurization device respectively, and is used to receive the electrode head depth, borehole head depth and pressurized water flow rate of each electrode at each stage, and calculate the permeability coefficient of each electrode at each stage accordingly.

[0021] This invention, through the use of multiple electrodes in a water head depth measuring device, can measure the electrode water head depth of each electrode within different scales of the borehole. In conjunction with a water pressure device, based on the electrode water head depth of each electrode and the water pressure flow rate at each stage, it can calculate the permeability coefficient within a multi-scale range, achieving larger-scale permeability coefficient measurement. Compared to the traditional water pressure test scheme of one test hole and one observation hole, this invention improves the effectiveness in measuring permeability coefficients at multiple or larger scales. The traditional water pressure test scheme of one test hole and one observation hole results in the measurement of permeability in the rock mass... The calculation is based on the assumption of isotropic permeability, while natural rock mass seepage is anisotropic. This invention, through the setting of multiple electrodes in the water head burial depth measuring device, can deploy electrodes in different directions to accurately measure the different permeability coefficients in different directions caused by the anisotropy of rock mass seepage. In traditional methods, the permeability coefficient cannot be directly converted from the results of water pressure tests, that is, it cannot be directly calculated using water pressure flow rate. It can only calculate the reference value of the permeability coefficient through empirical formulas. However, this invention can directly calculate the permeability coefficient of the rock mass based on water pressure flow rate, electrode water head burial depth, and borehole water head burial depth, making the measurement more convenient.

[0022] Example 2

[0023] like Figure 1 As shown, this embodiment provides a permeability coefficient measuring device, including a water head burial depth measuring device, a drill rod 9, a water pressurizing device 6, a water supply tank 5, a pressure gauge 21, a water connector 7, a filter 11, a first packer 10, a second packer 23, a controller, and a pressure measuring tube 22; the water pressurizing device 6 includes an inlet pipe 12, a high-pressure water pump 15, a three-way flow regulating valve 14, a return water pipe 13, a flow totalizer 16, a switch 17, a flow sensor 18, a pressure valve 19, and a high-pressure water pipe 20.

[0024] like Figure 1 As shown, drill rod 9 is used to drill a borehole 8 in the area of ​​the rock mass to be tested and remains in the borehole 8. Drill rod 9 has a hollow structure. In this embodiment, the diameter of the borehole 8 is 91 mm.

[0025] like Figure 1 and Figure 2As shown, within borehole 8, the upper end of drill rod 9 is connected to the lower end of water connector 7. The lower end of drill rod 9 passes through the first packer 10 and connects to the upper end of filter 11. The lower end of filter 11 is connected to the second packer 23, and the first packer 10 and the second packer 23 form a closed area. This closed area is the test section in this embodiment. The test section is sealed and isolated by the first packer 10 and the second packer 23, so that the water pressure test is only carried out within the test section. This structure allows the water pressurized into drill rod 9 by water pressure device 6 to flow into the test section after being filtered by filter 11. In this embodiment, the length of filter 11 is the length of the test section, which is 5m. Both the first packer 10 and the second packer 23 are hydraulic packers.

[0026] The pressure measuring tube 22 is connected to the test section and is used to assist in monitoring the water level changes in borehole 8.

[0027] like Figure 2 As shown, the outlet of the water supply tank 5 is connected to the inlet of the inlet pipe 12, the outlet of the inlet pipe 12 is connected to the inlet of the high-pressure water pump 15, the first port of the three-way flow regulating valve 14 is connected to the outlet of the high-pressure water pump 15, the second port of the three-way flow regulating valve 14 is connected to the inlet of the return pipe 13, and the third port of the three-way flow regulating valve 14 is connected in sequence to the switch 17, the flow sensor 18, and the pressure valve 19. The outlet of the return pipe 13 is connected to the return port of the water supply tank 5. The flow totalizer 16 is electrically connected to the flow sensor 18 and the controller, respectively, and is used to receive the flow data transmitted by the flow sensor 18 and calculate the pressurized water flow rate accordingly, and transmit the pressurized water flow rate to the controller. The outlet of the pressure valve 19 is connected to the water connector 7, and the pressure valve 19 is used to control and stabilize the test pressure. Based on the above structure, the water supplied by the water supply tank 5 is drawn by the high-pressure water pump 15 and passes through the three-way flow regulating valve 14, switch 17, flow sensor 18, pressure valve 19, high-pressure water pipe 20 and water connector 7 in sequence, enters the drill rod 9, and then enters the test section through the drill rod 9; excess water flows from the second interface of the three-way flow regulating valve 14 to the return water pipe 13, and then flows back to the water supply tank 5, realizing water recycling.

[0028] The flow sensor 18 consists of a large flow sensor and a small flow sensor with different accuracies, and is connected to the flow totalizer 16 to display the pressurized water flow rate in real time.

[0029] like Figure 2 As shown, pressure gauge 21 is installed at water connector 7 to monitor the test pressure in real time. The test pressure is the sum of the pressure indicated by the pressure gauge and the water column pressure from the center of the pressure gauge to the zero line of pressure calculation.

[0030] like Figure 1As shown, the groundwater head depth measuring device includes a main unit 1, an electrode converter 2, a cable 3, and multiple electrodes 4. The main unit 1 is connected to the electrode converter 2 and the controller via signals. The electrode converter 2 is electrically connected to each electrode 4 via the cable 3. The groundwater head depth measuring device is used to measure the electrode groundwater head depth and borehole groundwater head depth of each electrode 4 using high-density electrical resistivity tomography. The electrode groundwater head depth is defined as the groundwater head depth at the corresponding location of the electrode 4. Multiple electrodes 4 are arranged horizontally and vertically on the ground surface around the borehole 8 to collect resistivity signals at different locations in the rock mass, thereby monitoring the groundwater level depth and seepage range. In this embodiment, there are 120 electrodes 4. Figure 1 Only a portion of electrode 4 is shown as an example; not all of them are displayed.

[0031] The working process of the permeability measuring device provided in this embodiment is as follows: Step S1: Install according to the location of the test section, such as Figure 2 The equipment required for the pressure test shown has a test section length of 5m. Two water head burial depth measuring devices are set up through borehole 8 in both the horizontal and vertical directions. 120 electrodes 4 are connected to electrode converter 2 through cable 3. Electrode converter 2 is connected to host 1.

[0032] Step S2: Before the water pressure test, the initial borehole water head depth and the initial resistivity field around borehole 8 are measured using a water head depth measuring device. A fixed electrode spacing and bidirectional observation mode are set on the main unit 1. The power supply and measuring electrodes are automatically switched through the electrode converter 2. The resistivity data of the rock mass around borehole 8 are collected point by point to form an initial resistivity profile. Utilizing the water level-resistivity response characteristics, i.e., the significant electrical difference between the saturated and unsaturated zones, the resistivity abrupt change interface is identified, and the initial groundwater head depth at the corresponding position of each electrode 4 is accurately determined. The initial water level value of the measuring point inside borehole 8 is recorded simultaneously to complete the initial hydrogeological parameter collection before the test.

[0033] Step S3: Turn on the water pressure device 6. Open the three-way flow regulating valve 14 and switch 17 in sequence to start the high-pressure water pump 15. Water from the water supply tank 5 flows into the high-pressure water pump 15 through the inlet pipe 12, and then through the flow sensor 18, pressure valve 19, high-pressure water pipe 20, water connector 7, and drill rod 9 into the test section. The pressure is controlled by adjusting the pressure valve 19 to ensure stable pressure transmission to the test section within the borehole 8, achieving precise setting of the test pressure. The high-pressure water pump 15 provides stable water pressure, the three-way flow regulating valve 14 distributes the supply and return water flow, the flow sensor 18 collects flow signals in real time, the pressure valve 19 controls the test pressure, and the pressure gauge 21 monitors the borehole pressure in real time. All components work together to ensure the water pressure test is conducted under stable pressure and flow conditions.

[0034] Step S4: Observe the reading of pressure gauge 21. After the test pressure reaches the predetermined value and remains stable, observe the pressurized water flow rate. The test pressure is the sum of the pressure indicated by the pressure gauge and the water column pressure from the center of the pressure gauge to the zero line of the pressure calculation. The pressurized water flow rate is observed every 10 minutes. After the test pressure and pressurized water flow rate stabilize, measure the stable groundwater level in borehole 8 and use high-density electrical resistivity to measure the depth of the pressurized groundwater level. The pressurized water test continuously injects water into the rock test section. The water diffuses along the rock fissures to the surrounding area, forming a water pressure diffusion field centered on the pressurized water hole. The high-density electrical resistivity tomography monitors the change in rock resistivity through electrode 4. By utilizing the electrical difference between saturated and unsaturated rock masses, the range and depth of water level rise are identified, and the hydraulic parameters after water pressure diffusion are obtained, providing water level depth data for permeability coefficient calculation.

[0035] Step S5: Adjust the pressure according to the test plan, following a three-stage pressure gradient and five pressure stages: the pressures for the first three pressurization stages are 0.3 MPa, 0.6 MPa, and 1.0 MPa, respectively, and the pressures for the last two depressurization stages are 0.6 MPa and 0.3 MPa, respectively. Staged pressurization and depressurization allow rock fissures to fully conduct water under different hydraulic gradients, avoiding rock disturbances caused by sudden pressure changes, ensuring a stable seepage field under different pressure levels, thereby obtaining a more reliable flow-pressure response relationship and improving the accuracy of permeability coefficient calculation.

[0036] Step S6: In each stage, the controller stops the water pumping device 6 in response to any of the following conditions being met by the water flow rate: Condition 1: The flow rate of the water pressure test is not less than 5L / min for four consecutive tests, and the difference between the maximum and minimum values ​​is less than 10% of the flow rate of the last test. Condition 2: The flow rate of the water pressure test is less than 5 L / min for four consecutive tests, and the difference between the maximum and minimum values ​​is less than 20% of the flow rate of the last test. Condition 3: The flow rate of the pressurized water is less than 0.5 L / min for four consecutive times.

[0037] Stable flow rate indicates that the rock mass seepage has reached a stable radial flow state, satisfying the applicable conditions of Darcy's law. At this time, the recorded stable flow rate, stable pressure, water level depth, and other parameters can be directly substituted into the formula to calculate the permeability coefficient, ensuring that the results truly reflect the permeability characteristics of the rock mass.

[0038] After the test pressure stabilizes, the controller calculates the permeability coefficient using the following formula: ; in, Indicates the first The permeability coefficient at each electrode position Indicates the water pressure flow rate. Represents the natural logarithm function. Indicates the drilling and the first The distance between the electrodes Indicates the borehole radius. Represents pi (π). Indicates the length of the test section. Indicates the depth of the borehole water head. Indicates the first The depth of the electrode head for each electrode.

[0039] The derivation of the above formula for calculating the permeability coefficient is as follows: During the water pressure process, the water pressure gradually diffuses from the high-pressure area to the low-pressure area, centered on the borehole. When borehole 8 and electrode 4 form a hydraulic connection, a water pressure drop curve is formed between the two points. Let... The drilling water pressure; For pressurized water pressure; This refers to the borehole head height; This refers to the electrode head height; Indicates the depth of the borehole head; Indicates the first The electrode head burial depth of each electrode can be measured using resistivity abrupt change points using high-density electrical resistivity tomography equipment; the ground elevation is... ; This refers to the borehole flow rate; This is the distance between the borehole and the electrode; The distance from the borehole to any calculated cross-section; The radius of the borehole; The length of the test section; Distance from borehole Hydraulic gradient; Distance from borehole Hydraulic gradient; Indicates the first The permeability coefficient at each electrode location. When the pressurized water flow rate and test pressure reach a relatively stable condition, the total flow rate is equal at any cross-section. Therefore, the distance from the borehole... and There are two locations According to Darcy's Law, we have: (1); Therefore: (2); Distance drilling The head increment at that point is: (3); Between borehole 8 and electrode 4, there is: (4); Substituting formula (2) into formula (4) yields: (5); Therefore, we can conclude that: (6); water head height It cannot be measured directly because: (7); According to formulas (6) and (7), we can obtain The calculation formula is as follows: (8); Substituting formula (8) into formula (1), we get: (9); Then the universal permeability coefficient can be obtained. The calculation formula is as follows: (10).

[0040] After obtaining the permeability coefficients of each electrode 4 at each stage, the following analysis can be performed: by comparing the permeability coefficients of different electrodes 4 at the same monitoring section, the multi-scale permeability characteristics of the rock mass under different influence radii can be obtained; by comparing the numerical differences, variation patterns and water pressure diffusion range differences of the permeability coefficients in the horizontal and vertical directions, the anisotropic characteristics of rock mass permeability and the dominant seepage direction can be determined.

[0041] Example 3

[0042] This embodiment provides a method for measuring permeability, implemented based on the permeability measuring device provided in Embodiment 1, including: Drill a borehole and install the permeability measuring device; Turn on the water pressurization device and start measuring the water pressurization flow rate at regular intervals after the test pressure stabilizes. Press water into the test section in the order of first executing the pressurization stage and then the depressurization stage. During the pressurization stage or the depressurization stage, stop the water pressurization when the water pressurization flow rate meets the preset conditions, and take the last water pressurization flow rate as the water pressurization flow rate of the current pressurization stage or the depressurization stage. The electrode head depth and borehole head depth of each electrode are measured using a head depth measuring device. Based on the electrode head depth, borehole head depth, and pressurized water flow rate at each stage, calculate the permeability coefficient of each electrode at each stage.

[0043] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A permeability coefficient measuring device, characterized by, It includes a head depth measuring device, drill rod, water pressurization device, water supply tank, pressure gauge, water connector, filter, first packer, second packer and controller; The drill rod is used to drill a borehole in the rock mass area to be tested and remains in the borehole. The drill rod has a hollow structure. After passing through the first packer, the drill rod connects to the filter. The filter connects to the second packer. The enclosed area between the first and second packers is the test section. The head depth measuring device includes a main unit, an electrode converter, and multiple electrodes. The main unit is connected to the electrode converter and the controller for signal transmission. The electrode converter is electrically connected to each electrode. The head depth measuring device is used to measure the electrode head depth and borehole head depth of each electrode using a high-density electrical resistivity tomography method. The water supply tank is used to supply water to the water pressure device. The water pressure device uses... The water connector connects to the drill rod, and the water pressurization device pressurizes water into the test section through the drill rod and measures the pressurized water flow rate at regular intervals. The water pressurization process includes multiple pressurization stages and multiple depressurization stages. During the pressurization or depressurization stages, the water pressurization device is also used to stop the water pressurization when the pressurized water flow rate meets the preset conditions, and the last pressurized water flow rate is used as the pressurized water flow rate of the current pressurization or depressurization stage. The controller is connected to the head depth measuring device and the water pressurization device respectively, and is used to receive the electrode head depth, borehole head depth and pressurized water flow rate of each electrode at each stage, and calculate the permeability coefficient of each electrode at each stage accordingly.

2. The permeability measuring device according to claim 1, characterized in that, Multiple electrodes are arranged horizontally and vertically on the ground surface around the borehole.

3. The permeability measuring device according to claim 1, characterized in that, The water pressurization device includes an inlet pipe, a high-pressure water pump, a three-way flow regulating valve, a return pipe, a flow totalizer, a switch, a flow sensor, and a pressure valve; The inlet end of the inlet pipe is connected to the outlet of the water supply tank, the outlet end of the inlet pipe is connected to the inlet end of the high-pressure water pump, the first port of the three-way flow regulating valve is connected to the outlet end of the high-pressure water pump, the second port of the three-way flow regulating valve is connected to the inlet end of the return water pipe, the third port of the three-way flow regulating valve is connected in sequence to the switch, the flow sensor and the pressure valve, and the outlet end of the return water pipe is connected to the return water port of the water supply tank. The flow totalizer is electrically connected to the flow sensor and the controller respectively. It is used to receive the flow data transmitted from the flow sensor and calculate the pressurized water flow rate accordingly, and then transmit the pressurized water flow rate to the controller. The outlet end of the pressure valve is connected to the water connector.

4. The permeability measuring device according to claim 1, characterized in that, The water pressurization process includes a first pressurization stage, a second pressurization stage, a third pressurization stage, a first depressurization stage, and a second depressurization stage. The water pressure relationship in each stage of the pressurization process is as follows: first pressurization stage < second pressurization stage < third pressurization stage, third pressurization stage > first depressurization stage > second depressurization stage.

5. The permeability measuring device according to claim 1, characterized in that, The step of stopping water pumping when the water flow rate meets a preset condition includes: stopping water pumping when the water flow rate meets any one of the following conditions; Condition 1: The flow rate of water pressure in N consecutive tests is not less than 5 L / min, and the difference between the maximum and minimum values ​​is less than 10% of the flow rate of the last test. Condition 2: The flow rate of the water press is less than 5L / min for N consecutive times, and the difference between the maximum and minimum values ​​is less than 20% of the flow rate of the last water press. Condition 3: The flow rate of the pressurized water is less than 0.5 L / min for N consecutive times.

6. The permeability measuring device according to claim 1, characterized in that, The permeability coefficient is calculated using the following formula: ； in, Indicates the first The permeability coefficient at each electrode position Indicates the water pressure flow rate. Represents the natural logarithm function. Indicates the drilling and the first The distance between the electrodes Indicates the borehole radius. Represents pi (π). Indicates the length of the test section. Indicates the depth of the borehole water head. Indicates the first The depth of the electrode head for each electrode.

7. The permeability coefficient measuring device according to claim 1, characterized in that, It also includes a pressure gauge, which is installed on the water connector to monitor the test pressure. The test pressure is the sum of the pressure indicated by the pressure gauge and the water column pressure from the center of the pressure gauge to the zero line of the pressure calculation. After the test pressure stabilizes, the controller receives the electrode head depth, borehole head depth, and pressurized water flow rate of each electrode at each stage, and calculates the permeability coefficient of each electrode at each stage accordingly.

8. A method for measuring permeability coefficient, characterized in that, Based on the permeability measuring device according to any one of claims 1 to 7, comprising: Drill a borehole and install the permeability measuring device; Turn on the water pressurization device and start measuring the water pressurization flow rate at regular intervals after the test pressure stabilizes. Press water into the test section in the order of first executing the pressurization stage and then the depressurization stage. During the pressurization stage or the depressurization stage, stop the water pressurization when the water pressurization flow rate meets the preset conditions, and take the last water pressurization flow rate as the water pressurization flow rate of the current pressurization stage or the depressurization stage. The electrode head depth and borehole head depth of each electrode are measured using a head depth measuring device. Based on the electrode head depth, borehole head depth, and pressurized water flow rate at each stage, calculate the permeability coefficient of each electrode at each stage.

9. The method for measuring permeability coefficient according to claim 8, characterized in that, The permeability coefficient is calculated using the following formula: ； in, Indicates the first The permeability coefficient at each electrode position Indicates the water pressure flow rate. Represents the natural logarithm function. Indicates the drilling and the first The distance between the electrodes Indicates the borehole radius. Represents pi (π). Indicates the length of the test section. Indicates the depth of the borehole water head. Indicates the first The depth of the electrode head for each electrode.

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