Testing Method and Experimental Device for Permeability Coefficient of Fractured Rock Mass

Abstract

The present invention provides a method and an experimental device for testing the permeability coefficient of fractured rock masses. The testing method includes the following steps: Prepare an experimental box body, lay the test sample in the experimental box body, close the valve at the outlet end, open the valve at the inlet end, inject an external water source into the experimental box body, and submerge the test sample. Open the valve at the outlet end to allow the water in the experimental box body to drain through the valve at the outlet end, and adjust the size of the valve at the outlet end to control the flow rate Q1 at the outlet end to be greater than the flow rate Q2 at the inlet end. Adjust the size of the valve at the outlet end to make the flow rate at the inlet end equal to the flow rate at the outlet end, and record the liquid level height on the inlet end side at this time as the calibration height h1 at the inlet end, the liquid level height on the outlet end side as the calibration h2 at the outlet end, and the flow rate at the inlet end as the calibration flow rate Q at the inlet end. Use the formula to obtain the permeability coefficient k. The method for testing the permeability coefficient of fractured rock masses of the present invention has the advantages of short test period, low test cost, and repeatable test operation.

Description

Technical Field

[0001] The present invention belongs to the technical field of geological environment detection, and specifically relates to a method for testing the permeability coefficient of fractured rock masses and an experimental device therefor. Background Art

[0002] High-intensity coal resource mining has formed about 2 million hm 2 of coal mining subsidence areas. With the rapid development of the national economy and the national urbanization process, the geological safety problems brought about by goaf subsidence have become increasingly prominent, and the tension between major engineering construction and the supply of constructible land has become increasingly acute. More and more coal mining subsidence areas (goafs) urgently need to be treated and transformed into constructible land. Among the many methods for treating coal mining subsidence areas, grouting filling is one of the most widely used and effective methods. And the permeability coefficient of fractured rock masses is a key parameter for grouting filling design.

[0003] In related technologies, the traditional methods for obtaining the formation permeability coefficient mainly include water pressure tests and pumping tests. After coal seam mining, the overlying strata collapse and the strata are fractured. Both water pressure tests and pumping tests need to be carried out with the aid of exploration boreholes. Drilling construction in fractured strata is difficult, costly, and time-consuming. Moreover, the goaf depth is often relatively deep, dozens of meters or even hundreds of meters, and the test equipment is expensive and the installation cost is high. In addition, the test results of pumping tests in the same formation often have an order-of-magnitude difference, the data is discrete, and the accuracy is low. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems in the related technologies to some extent.

[0005] To this end, an embodiment of the present invention provides a method for testing the permeability coefficient of fractured rock masses, which has the advantages of short test period, low cost, and repeatable operation.

[0006] An embodiment of the present invention provides an experimental device for testing the permeability coefficient of fractured rock masses, which has the advantages of short test period, low cost, and repeatable operation.

[0007] The method for testing the permeability coefficient of fractured rock masses according to the embodiment of the present invention includes the following steps:

[0008] S1. Prepare an experimental box body and lay the test sample in the experimental box body;

[0009] S2. Close the outlet valve of the experimental box body, open the inlet valve of the experimental box body, inject external water source into the experimental box body through the inlet valve, and submerge the test sample with water in the experimental box body;

[0010] S3. Open the valve at the outlet end of the experimental chamber to drain the water in the test chamber through the outlet end valve, and adjust the size of the outlet end valve to control the flow rate Q at the outlet end. 1 which is greater than the flow rate Q at the inlet end. 2 , so that the liquid level height H on the inlet end side 1 is greater than the liquid level height H on the outlet end side. 2 ;

[0011] S4. Adjust the size of the outlet end valve so that the flow rate at the inlet end is equal to the flow rate at the outlet end, and record the liquid level height on the inlet end side at this time as the calibrated height h of the inlet end 1 , the liquid level height on the outlet end side as the calibrated height h of the outlet end 2 and the flow rate at the inlet end as the calibrated flow rate Q of the inlet end;

[0012] S5. Use to obtain the permeability coefficient k;

[0013] where L is the length of the experimental chamber and B is the width of the test chamber.

[0014] The method for testing the permeability coefficient of fractured rock mass in the embodiment of the present invention uses adjusting the inlet end valve and the outlet end valve to achieve the seepage balance of the test sample, and the permeability coefficient can be conveniently calculated using the recorded parameters.

[0015] In addition, after the test is completed in the method for testing the permeability coefficient of fractured rock mass in the embodiment of the present invention, the water in the test chamber is drained, and the same test sample can be used again for the test to obtain a new permeability coefficient, thereby increasing the accuracy of the data.

[0016] Therefore, the method for testing the permeability coefficient of fractured rock mass in the embodiment of the present invention has the advantages of short test period, low test cost, and repeatable test operation.

[0017] In some embodiments, in S2, the flow rate Q at the inlet end 1 is greater than or equal to 65% and less than or equal to 83% of the maximum flow rate at the inlet end,

[0018] In S3, the flow rate Q at the outlet end 1 is greater than or equal to 1.1 and less than or equal to 1.2 compared with the flow rate Q at the inlet end. 2

[0019] In some embodiments, in S3, adjust the size of the outlet end valve so that the ratio of the liquid level height H on the outlet end side 2 to the liquid level height H on the inlet end side 1 is greater than or equal to 70% and less than or equal to 80%.

[0020] In some embodiments, in S4, record the calibration height h of the inlet end 1 and the calibration height h of the outlet end 2 The steps of and the calibration flow rate Q of the inlet end include: recording the calibration height h of the inlet end once every preset time interval 1 and the calibration height h of the outlet end 2 and the calibration flow rate Q of the inlet end. The ratio of the calibration height of the inlet end in the latter record to the calibration height of the inlet end in the previous record in two adjacent records is greater than 97%, and the ratio of the calibration height of the outlet end in the latter record to the calibration height of the outlet end in the previous record in the two adjacent records is greater than 97%.

[0021] In some embodiments, the method for testing the permeability coefficient of fractured rock mass according to the embodiment of the present invention further includes the following steps:

[0022] S6. Repeat S2, S3, S4 and S5 to obtain multiple permeability coefficients;

[0023] S7: Calculate the average value of the multiple permeability systems.

[0024] In some embodiments, in S6, the error between the multiple permeability coefficients is not greater than D 0 where D 0 = 2×10 -n .

[0025] In some embodiments, the method for testing the permeability coefficient of fractured rock mass according to the embodiment of the present invention further includes the following steps:

[0026] Before S1,

[0027] Using the sieving method, obtain the restricted particle size d 60 and the effective particle size d 10 and the particle size d with a cumulative particle content of 30%; 30 ;

[0028] Calculate the coefficient of uniformity and the coefficient of curvature to determine the block size and gradation of the fractured rock mass;

[0029] Configure the test sample according to the block size and gradation of the fractured rock mass.

[0030] In some embodiments, in S1, the laying height of the experimental sample is 80% - 85% of the height of the test box.

[0031] In some embodiments, in S2, the water level height submerging the test sample in the test box is 1 - 2 cm higher than the height of the test sample.

[0032] The permeability coefficient test device for fractured rock mass according to the embodiments of the present invention can implement the permeability coefficient test method for fractured rock mass described in any one of the above embodiments. The test device includes:

[0033] A test box body, which includes a water inlet and a water outlet arranged at intervals in the length direction of the test box body. The water inlet is above the water outlet in the height direction of the test box body, and the test sample can be arranged in the test box body;

[0034] An inlet end valve and an outlet end valve. The inlet end valve is arranged at one end of the test box body adjacent to the water inlet to adjust the flow rate of the water inlet, and the outlet end valve is arranged at one end of the test box body adjacent to the water outlet to adjust the flow rate of the water outlet;

[0035] A first flowmeter and a second flowmeter. The first flowmeter is used to measure the flow rate of the water inlet, and the second flowmeter is used to measure the flow rate of the water outlet;

[0036] A first water level scale and a second water level scale. The first water level scale is connected to the test box body and is arranged adjacent to the water inlet. The first water level scale is used to measure the water level height at one end of the test box body adjacent to the water inlet. The second water level scale is connected to the test box body and is arranged adjacent to the water outlet. The second water level scale is used to measure the water level height at one end of the test box body adjacent to the water outlet;

[0037] A water storage tank and a drainage tank. The water storage tank is connected to the water inlet through a first pipeline, and the drainage tank is connected to the water outlet through a second pipeline;

[0038] A water pump, which is arranged on the first pipeline. The water pump is used to pump water from the water storage tank and discharge it into the test box body through the water inlet. Description of the Drawings

[0039] Figure 1 It is a schematic flow chart of the permeability coefficient test method for fractured rock mass according to the embodiments of the present invention.

[0040] Figure 2 It is a schematic structural diagram of the permeability coefficient test device for fractured rock mass according to the embodiments of the present invention.

[0041] Figure 3 It is a schematic structural diagram of the test box body of the permeability coefficient test device for fractured rock mass according to the embodiments of the present invention.

[0042] Reference Signs:

[0043] Test box body 1; water inlet 11; water outlet 12;

[0044] Inlet valve 21; Outlet valve 22;

[0045] First flowmeter 31; Second flowmeter 32;

[0046] First water level scale 41; Second water level scale 42;

[0047] Water storage tank 5;

[0048] Drainage tank 6;

[0049] First pipeline 71; Second pipeline 72;

[0050] Water pump 8. Specific implementation manner

[0051] The embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the drawings. The embodiments described below with reference to the drawings are exemplary and are intended to explain the present invention, and should not be construed as limiting the present invention.

[0052] The method for testing the permeability coefficient of fractured rock mass according to the embodiments of the present invention will be described below with reference to the drawings.

[0053] As Figure 1 shown, the method for testing the permeability coefficient of fractured rock mass in the embodiments of the present invention includes the following steps:

[0054] S1. Prepare the test box 1 and lay the test sample in the test box. It can be understood that the test box 1 is a rectangular box, and the material of the test box 1 can be tempered organic glass, and of course, it can also be made of other transparent materials with higher hardness. Optionally, the length L of the test box 1 is 100 - 120 cm, the width B of the test box 1 is 30 - 40 cm, and the height H of the test box 1 is 50 - 60 cm. Preferably, the size of the test box 1 is L = 100 cm, B = 30 cm, and H = 50 cm. Of course, the test box 1 can also select different sizes according to actual situations.

[0055] In addition, preferably, the laying height of the test sample is 80% - 85% of the height of the test box 1, so as to avoid the laying height of the test sample being too high and overflowing from the test box 1 during the experiment, affecting the test results.

[0056] S2. Close the outlet valve 22 of the test box and open the inlet valve 21 of the test box 1, inject the external water source into the test box 1 through the inlet valve 21, and submerge the test sample with the water in the test box. It can be understood that by adjusting the opening sizes of the inlet valve 21 and the outlet valve 22, the flow rate at the inlet and the flow rate at the outlet can be adjusted. Preferably, as Figure 2As shown, the water inlet 11 and the water outlet 12 are respectively arranged on the left and right sides of the test box body 1, that is, the water inlet 11 is arranged at the left end of the test box body 1, and the water outlet 12 is arranged at the right end of the test box body 1, and the water inlet 11 is located above the water outlet 12 in the height direction of the test box body 1 (such as Figure 1 the up and down direction in

[0057] In addition, preferably, the water level height of the test sample immersed in the test box body 1 is 1-2 cm higher than the height of the test sample to ensure that the test sample can be completely immersed in water.

[0058] S3. Open the valve 22 at the outlet end of the experimental box body, so that the water in the test box body 1 is discharged through the valve 22 at the outlet end, and adjust the size of the valve 22 at the outlet end to control the flow rate Q at the outlet end 1 to be greater than the flow rate Q at the inlet end 2 , so that the liquid level height H 1 on the inlet end side is greater than the liquid level height H 2 on the outlet end side.

[0059] It can be understood that, as Figure 2 shown, according to the positions of the water inlet 11 and the water outlet 12, make the flow rate Q at the outlet end 1 greater than the flow rate Q at the inlet end 2 , then, the water near the water outlet 12 in the test box body 1 will be quickly discharged, resulting in the inclination of the liquid level in the test box body 1, that is, the liquid level height at the left end in the test box body 1 is higher than the liquid level height at the right end in the test box body 1. Therefore, the liquid level height H 1 on the inlet end side and the liquid level height H 2 on the outlet end side can be measured respectively by using a water level scale.

[0060] S4. Adjust the size of the valve 22 at the outlet end to make the flow rate at the inlet end equal to the flow rate at the outlet end, and record the liquid level height on the inlet end side at this time as the calibration height h 1 of the inlet end, the liquid level height on the outlet end side as the calibration h 2 of the outlet end, and the flow rate at the inlet end as the calibration flow rate Q of the inlet end.

[0061] It can be understood that when the flow rate at the inlet end is equal to the flow rate at the outlet end, the test sample in the test box body 1 reaches the seepage equilibrium.

[0062] S5. Use to obtain the permeability coefficient k; where L is the length of the experimental box body, and B is the width of the test box body 1.

[0063] It should be noted that according to Darcy's law Q = kiA, and the permeability coefficient k can be obtained, where i is the hydraulic gradient and A is the seepage end face area.

[0064] That is to say, the method for testing the permeability coefficient of fractured rock mass in the embodiment of the present invention adjusts the inlet valve 21 and the outlet valve 22 to achieve the seepage balance of the test sample, and the permeability coefficient can be conveniently calculated using the recorded parameters.

[0065] In addition, after the test is completed, the water in the test box 1 is drained in the method for testing the permeability coefficient of fractured rock mass in the embodiment of the present invention, and the same test sample can be used again for the test to obtain a new permeability coefficient, thereby increasing the accuracy of the data.

[0066] Therefore, the method for testing the permeability coefficient of fractured rock mass in the embodiment of the present invention has the advantages of short test period, low test cost, and repeatable test operation.

[0067] Preferably, in S2, the flow rate Q at the inlet end 1 is greater than or equal to 65% and less than or equal to 83% of the maximum flow rate at the inlet end. In S3, the flow rate Q at the outlet end 1 is greater than or equal to 1.1 and less than or equal to 1.2 compared with the flow rate Q at the inlet end. 2

[0068] It can be understood that in order to ensure that the water flow velocity on the side of the water outlet 12 is greater than that of the water inlet 11, so that the water level height at the left end of the test box 1 is greater than the water level height at the right end of the test box 1, it is necessary to ensure that the flow rate Q at the outlet end 2 is greater than the flow rate Q at the inlet end. 1

[0069] Preferably, in S3, the size of the outlet valve 22 is adjusted so that the ratio of the liquid level height H on the outlet end side 2 to the liquid level height H on the inlet end side 1 is greater than or equal to 70% and less than or equal to 80%.

[0070] It can be understood that since the water flow velocity at the outlet end is greater than that at the inlet end, the water in the test box 1 will gradually decrease. Preferably, the ratio of the liquid level height H on the outlet end side 2 to the liquid level height H on the inlet end side 1 is greater than or equal to 70% and less than or equal to 80%, so as to prevent the water in the test box 1 from flowing out too fast, resulting in insufficient water volume in the test box 1.

[0071] In other words, the water level in the test box 1 is controlled within the range that the difference between the liquid level height H on the inlet end side 1 and the liquid level height H on the outlet end side 2 accounts for 20% - 30% of the liquid level height H on the inlet end side. 1

[0072] It should be noted that when draining water through the water outlet 12, it is necessary to continuously observe the water level changes at both ends of the test box 1. Therefore, preferably, records are made every 5 minutes until the liquid level height H 2 on the side of the outlet end 1 is greater than or equal to 70% and less than or equal to 80% of the liquid level height H

[0073] Preferably, in S4, the steps of recording the calibration height h 1 at the inlet end, the calibration height h 2 at the outlet end, and the calibration flow rate Q at the inlet end include: recording the calibration height h 1 at the inlet end, the calibration height h 2 at the outlet end, and the calibration flow rate Q at the inlet end every preset time interval. The ratio of the calibration height at the inlet end in the subsequent record to the calibration height at the inlet end in the previous record in two adjacent records is greater than 97%, and the ratio of the calibration height at the outlet end in the subsequent record to the calibration height at the outlet end in the previous record in two adjacent records is greater than 97%.

[0074] It can be understood that when the water level in the test box 1 in S3 reaches the preset value (i.e., the ratio of the liquid level height H 2 on the side of the outlet end to the liquid level height H 1 on the side of the inlet end is greater than or equal to 70% and less than or equal to 80%), adjust the outlet end valve 22 to make the inlet end flow rate equal to the outlet end flow rate. At this time, since the adjustment of the valve size is a dynamic process, preferably, records are made every preset moving time, that is, the preset time is 5 minutes.

[0075] That is to say, after adjusting the outlet end valve 22 to make the inlet end flow rate equal to the outlet end flow rate, multiple records are made. There will be fluctuations between the data of each record. Preferably, when the ratio of the calibration height at the inlet end in the subsequent record to the calibration height at the inlet end in the previous record in two adjacent records is greater than 97%, and the ratio of the calibration height at the outlet end in the subsequent record to the calibration height at the outlet end in the previous record in two adjacent records is greater than 97%, it is considered that the seepage reaches equilibrium.

[0076] In some embodiments, the method for testing the permeability coefficient of fractured rock mass in the embodiments of the present invention further includes the following steps:

[0077] S6. Repeat S2, S3, S4, and S5 to obtain multiple permeability coefficients;

[0078] S7: Calculate the average value of multiple permeability coefficients.

[0079] It can be understood that before repeating S2, S3, S4, and S5, the water in the test chamber 1 can be drained through the water outlet 12, and then steps S2, S3, S4, and S5 can be repeated. That is to say, the method for testing the permeability coefficient of fractured rock masses in the embodiments of the present invention can achieve repeated operations and also has the advantage of a short test period.

[0080] Preferably, in S6, the error between multiple permeability coefficients is not greater than D 0 , where D 0 = 2 * 10 -n .

[0081] It can be understood that generally, the formation permeability coefficient can be expressed as: integer A * 10 -n . Since there are differences in multiple permeability coefficients obtained through multiple tests, therefore, each permeability coefficient is expressed by this expression, and it is ensured that the value of n in the expression is equal. Then, preferably, the difference between the integers A in two permeability coefficients is not greater than 2.

[0082] In some embodiments, the method for testing the permeability coefficient of fractured rock masses in the embodiments of the present invention further includes the following steps:

[0083] Before S1, using the sieving method, obtain the restricted particle size d 60 , effective particle size d 10 and the particle size d 30 with a cumulative particle content of 30%; calculate the coefficient of uniformity and coefficient of curvature, determine the block size and grading of the fractured rock mass; configure test samples according to the block size and grading of the fractured rock mass.

[0084] It can be understood that before S1, particle analysis needs to be carried out, that is, the particle shape and grading of the rock blocks in the tested fractured formation are analyzed. That is to say, analysis is carried out using the sieving method.

[0085] It should be noted that the coefficient of uniformity is: The coefficient of curvature is:

[0086] The following describes the test device for the permeability coefficient of fractured rock masses in the embodiments of the present invention according to the drawings.

[0087] As Figure 2 and Figure 3 shown, the test device for the permeability coefficient of fractured rock masses in the embodiments of the present invention can implement the method for testing the permeability coefficient of fractured rock masses according to any one of the above embodiments. The test device includes: a test chamber 1, an inlet end valve 21, an outlet end valve 22, a first flowmeter 31, a second flowmeter 32, a first water level scale 41, a second water level scale 42, a water storage tank 5, a drainage tank 6, and a water pump 8.

[0088] As Figure 1 andFigure 2 As shown, the test chamber 1 includes a water inlet 11 and a water outlet 12 arranged at intervals in the length direction of the test chamber 1 (such as Figure 1 the left - right direction in the figure), that is, the water inlet 11 is provided at the left end of the test chamber 1, the water outlet 12 is provided at the right end of the test chamber 1, the water inlet 11 is above the water outlet 12 in the height direction of the test chamber 1, and the water outlet 12 is arranged adjacent to the bottom of the test chamber 1 for drainage. The test sample can be arranged in the test chamber 1.

[0089] The inlet - end valve 21 is arranged at one end of the test chamber 1 adjacent to the water inlet 11 for adjusting the flow rate of the water inlet 11, and the outlet - end valve 22 is arranged at one end of the test chamber 1 adjacent to the water outlet 12 for adjusting the flow rate of the water outlet 12.

[0090] The first water - level scale 41 is connected to the test chamber 1 and arranged adjacent to the water inlet 11, and the first water - level scale 41 is used to measure the water - level height at one end of the test chamber 1 adjacent to the water inlet 11. The second water - level scale 42 is connected to the test chamber 1 and arranged adjacent to the water outlet 12, and the second water - level scale 42 is used to measure the water - level height at one end of the test chamber 1 adjacent to the water outlet 12.

[0091] The water storage tank 5 is communicated with the water inlet 11 through the first pipeline 71, and the drainage tank 6 is communicated with the water outlet 12 through the second pipeline 72.

[0092] The first flowmeter 31 is used to measure the flow rate of the water inlet 11, and the second flowmeter 32 is used to measure the flow rate of the water outlet 12. Specifically, the first flowmeter 31 is arranged on the first pipeline 71 and on the left side of the inlet - end valve 21, and the second flowmeter 32 is arranged on the second pipeline 72 and on the right side of the outlet - end valve 22.

[0093] The water pump 8 is arranged on the first pipeline 71. The water pump 8 is used to pump the water in the water storage tank 5 and discharge it into the test chamber 1 through the water inlet 11, and the water pump 8 is arranged adjacent to the water storage tank 5 for facilitating the pumping of the water in the water storage tank 5.

[0094] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counter - clockwise", "axial", "radial", "circumferential", etc. is the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying 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 construed as a limitation to the present invention.

[0095] In addition, the terms "first" and "second" are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0096] In the present invention, unless otherwise clearly defined and limited, terms such as "mounted", "connected", "coupled", "fixed", etc. shall be construed broadly. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection, an electrical connection, or communicable with each other; it may be directly connected, or indirectly connected through an intermediate medium, and may be the communication inside two elements or the interaction relationship between two elements, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0097] In the present invention, unless otherwise clearly defined and limited, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "below" and "beneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0098] In the present invention, terms such as "an embodiment", "some embodiments", "example", "specific example", or "some examples" etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0099] Although the above embodiments have been shown and described, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions, and variations made by those of ordinary skill in the art to the above embodiments are within the protection scope of the present invention.

Claims

1. A method for testing the permeability coefficient of fractured rock mass, characterized in that, it includes the following steps: S1. Prepare a test box body and lay the test sample in the test box body; S2. Close the valve at the outlet end of the test box body, open the valve at the inlet end of the test box body, inject external water source into the test box body through the inlet end valve, and submerge the water in the test box body with the test sample. The water inlet and the water outlet are respectively arranged on the left and right sides of the test box body, and the water inlet is above the water outlet in the height direction of the test box body; S3. Open the valve at the outlet end of the experimental chamber to drain the water in the test chamber through the outlet end valve, and adjust the size of the outlet end valve to control the flow rate Q at the outlet end. 1 Greater than the flow rate Q at the inlet end 2 , so that the liquid level height H on the inlet end side 1 Is greater than the liquid level height H on the outlet end side 2 ; S4. Adjust the size of the valve at the outlet end so that the flow rate at the inlet end is equal to the flow rate at the outlet end, and record the liquid level height on the inlet end side at this time as the calibration height h of the inlet end. 1 The liquid level height on the outlet end side is the calibration h of the outlet end. 2 And the flow rate at the inlet end is the calibration flow rate Q of the inlet end. S5. Use to obtain the permeability coefficient k; wherein, L is the length of the test box body, and B is the width of the test box body; In S2, the ratio of the flow rate Q1 at the inlet end to the maximum flow rate at the inlet end is greater than or equal to 65% and less than or equal to 83%, In S3, the flow rate Q at the outlet end 1 and the flow rate Q at the inlet end 2 have a ratio greater than or equal to 1.1 and less than or equal to 1.2; In S4, the steps of recording the calibration height h1 at the inlet end, the calibration height h2 at the outlet end, and the calibration flow rate Q at the inlet end include: recording the calibration height h1 at the inlet end, the calibration height h2 at the outlet end, and the calibration flow rate Q at the inlet end every preset time interval. The ratio of the calibration height at the inlet end in the latter record to the calibration height at the inlet end in the previous record in two adjacent records is greater than 97%, and the ratio of the calibration height at the outlet end in the latter record to the calibration height at the outlet end in the previous record in the two adjacent records is greater than 97%.

2. The method for testing the permeability coefficient of fractured rock mass according to claim 1, characterized in that, Adjust the size of the valve at the outlet end in S3 so that the liquid level height H on the outlet end side 2 is equal to the liquid level height H on the inlet end side 1 and the ratio is greater than or equal to 70% and less than or equal to 80%.

3. The method for testing the permeability coefficient of fractured rock mass according to claim 1, characterized in that, It further includes the following steps: S6. Repeat S2, S3, S4, and S5 to obtain multiple permeability coefficients; S7: Take the average value of multiple said permeability coefficients.

4. The method for testing the permeability coefficient of fractured rock mass according to claim 3, characterized in that, In S6, the error between multiple said permeability coefficients is not greater than D 0 , where D 0 = 2×10 -n .

5. The method for testing the permeability coefficient of fractured rock mass according to any one of claims 1-4, characterized in that, It further includes the following steps: Before S1, Using the sieving method, the restricted particle size d 60 , the effective particle size d 10 and the particle size d with a cumulative particle content of 30% 30 are obtained; Calculate the coefficient of non-uniformity and the coefficient of curvature to determine the block size and gradation of the fractured rock mass; Configure the test sample according to the block size and gradation of the fractured rock mass.

6. The method for testing the permeability coefficient of fractured rock mass according to claim 1, characterized in that, In S1, the laying height of the test sample is 80% - 85% of the height of the test box body.

7. The method for testing the permeability coefficient of fractured rock mass according to claim 1, characterized in that, In S2, the water level height submerging the test sample in the test box body is 1 - 2 cm higher than the height of the test sample.

8. A test device for the permeability coefficient of fractured rock mass, characterized in that, It can implement the method for testing the permeability coefficient of fractured rock mass according to any one of claims 1-7. The test device includes: A test box body, the test box body includes a water inlet and a water outlet arranged at intervals in the length direction of the test box body. The water inlet is above the water outlet in the height direction of the test box body, and the test sample can be configured in the test box body; An inlet valve and an outlet valve, wherein the inlet valve is arranged at one end of the test box adjacent to the water inlet for adjusting the flow rate of the water inlet, and the outlet valve is arranged at one end of the test box adjacent to the water outlet for adjusting the flow rate of the water outlet; A first flowmeter and a second flowmeter, wherein the first flowmeter is used to measure the flow rate of the water inlet, and the second flowmeter is used to measure the flow rate of the water outlet; A first water level scale and a second water level scale, wherein the first water level scale is connected to the test box and is arranged adjacent to the water inlet, and the first water level scale is used to measure the water level height at one end of the test box adjacent to the water inlet, and the second water level scale is connected to the test box and is arranged adjacent to the water outlet, and the second water level scale is used to measure the water level height at one end of the test box adjacent to the water outlet; A water storage tank and a drainage tank, wherein the water storage tank is communicated with the water inlet through a first pipeline, and the drainage tank is communicated with the water outlet through a second pipeline; A water pump, which is arranged on the first pipeline, and the water pump is used to pump water from the water storage tank and discharge it into the test box through the water inlet.

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