A rock permeability testing method based on rapid water injection

Abstract

The present invention provides a rock permeability test method and a rock permeability test system based on rapid water injection. The method is applied to a rock permeability test system based on rapid water injection, and the method comprises: S1, a data processing device obtains a static water level in a borehole measured by a liquid level sensor; S2, when a test pipe introduces clean water into the borehole, the data processing device obtains the test water levels respectively measured by the liquid level sensor at n moments, and calculates the water head based on each moment according to the static water level in S1 and the test water level at each moment; S3, the data processing device calculates the permeability coefficient of the target rock mass according to the size parameters of the borehole, the size parameters of the test section, the size parameters of the test pipe, and the water head based on each moment calculated in S3. The present invention can quickly and accurately calculate the permeability coefficient of the rock mass and obtain accurate test results.

Description

Technical Field

[0001] The invention relates to the technical field of rock mass permeability testing, and in particular to a rock mass permeability testing method and a rock mass permeability testing system based on rapid water injection. Background Art

[0002] Rock permeability is an important indicator for studying the hydraulic properties of rock. Taking groundwater as an example, the better the rock permeability, the faster the groundwater movement speed under the same conditions, and the better the water-richness of the groundwater. In the process of groundwater exploitation, rock permeability is of great significance for evaluating the development potential of water sources. It not only helps to prevent over-exploitation and water resource depletion, but also ensures the sustainable use of groundwater. In addition, in the field of underground engineering, the permeability characteristics of rock mass are crucial hydrogeological parameters in engineering design, which can effectively predict the impact of groundwater on engineering structures, thereby ensuring the safety of construction. Therefore, the test of rock permeability has important practical significance in the fields of groundwater science and underground engineering.

[0003] At present, the commonly used method for determining rock permeability is to conduct permeability tests by means of pumping, water pressure, water injection and oscillation, and then calculate the permeability coefficient based on the test data. Among them, the pumping test can obtain multiple test parameters and the data is accurate, but it has the disadvantages of large borehole diameter requirements, high test cost and long test time; the water pressure test is less applicable in high permeability rock and deep test sections; and the permeability coefficient test of the water injection test and the oscillation permeability test is simple, fast, low cost and widely applicable, but the accuracy of the test results will be low. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a rock permeability testing method, which solves the problem of inaccurate test results in the rock permeability testing methods commonly used in the prior art, especially the rock permeability measurement methods based on water injection.

[0005] According to an embodiment of the present invention, a rock permeability testing method is applied to a rock permeability testing system based on rapid water injection, wherein the rock permeability testing system based on rapid water injection comprises a drilling device, a liquid level sensor, a test tube and a data processing device, wherein the drilling device performs construction drilling in a to-be-detected area of ​​a target rock mass, and after the drilling is completed, the liquid level sensor and the test tube are installed, and a designated portion of the drilling is a test section;

[0006] The rock mass permeability testing method comprises:

[0007] S1, the data processing device obtains the static water level in the borehole measured by the liquid level sensor;

[0008] S2. After the test pipe introduces clean water into the borehole, the data processing device obtains the test water levels measured by the liquid level sensor at n moments respectively, and calculates the water head at each moment according to the static water level in S1 and the test water level at each moment;

[0009] S3. The data processing device calculates the permeability coefficient of the target rock mass according to the dimension parameters of the borehole, the dimension parameters of the test section, the dimension parameters of the test pipe, and the water head calculated in S3 at each moment.

[0010] Optionally, the method further includes: verifying the permeability coefficient in S3;

[0011] If the verification fails, the steps S1 to S3 are executed again.

[0012] Optionally, in S3, the permeability coefficient of the target rock mass is calculated using the formula:

[0013]

[0014] Among them, s n According to t n The test water level recorded at the time and the static water level in S3 are obtained based on t n The water head at the moment, n = 0, 1, 2; K is the permeability coefficient, in meters per second; m is the slope of the natural logarithm of the water head and time; r1 is the diameter of the test tube, in meters; l is the length of the test section, in meters; r w is the radius of the test section, in meters.

[0015] On the other hand, a rock permeability testing system based on rapid water injection is provided, comprising a drilling device, a liquid level sensor, a test tube and a data processing device;

[0016] The drilling device is used to construct a drilling hole in the area to be detected in the target rock mass; wherein the liquid level sensor and the test tube are installed after the drilling is completed, and the designated part in the drilling hole is the test section;

[0017] The liquid level sensor is used to measure the static water level in the borehole;

[0018] The test pipe is used to introduce clean water into the borehole;

[0019] The liquid level sensor is also used to measure the test water level at n moments after the test pipe introduces clean water into the borehole;

[0020] The data processing device is used to calculate the water head based on each moment according to the static water level measured by the liquid level sensor and the test water level at each moment; it is also used to calculate the permeability coefficient of the target rock mass according to the size parameters of the borehole, the size parameters of the test section, the size parameters of the test pipe and the calculated water head based on each moment.

[0021] Optionally, the data processing device calculates the permeability coefficient of the target rock mass using the formula:

[0022]

[0023] Among them, s n According to t n The test water level recorded at the time and the static water level in S3 are obtained based on t n The water head at the moment, n = 0, 1, 2; K is the permeability coefficient, in meters per second; m is the slope of the natural logarithm of the water head and time; r1 is the diameter of the test tube, in meters; l is the length of the test section, in meters; r w is the radius of the test section, in meters.

[0024] Optionally, the test pipe is installed in the borehole, and the liquid level sensor is installed in the borehole and the test pipe and is below the groundwater level line.

[0025] Optionally, a water stop device is also included;

[0026] The water-stop device is installed at the top of the test section, the test pipe is installed in the borehole and on the water-stop device, and the liquid level sensor is installed in the borehole and the test pipe and is below the groundwater level line.

[0027] Optionally, the relative distance between the liquid level sensor and the groundwater level line is greater than 10 meters.

[0028] Optionally, a water injection device is also included, which is connected to the test pipe to provide clean water to be introduced into the borehole.

[0029] Optionally, a single water injection time set in the water injection device is less than 1 minute, and a single water injection volume is set so that the test water level measured by the liquid level sensor at the first moment is 4 to 10 meters higher than the static water level.

[0030] The beneficial effects of the present invention are as follows: the present invention is implemented based on the hydrodynamic principle of rock mass, firstly, clean water is introduced into the borehole through a test pipe to realize rapid water injection, then the water level drop process in the borehole is observed through a liquid level sensor, and then based on the incomplete well formula in a semi-infinite thick aquifer, a formula for calculating the permeability coefficient of the rock mass is provided by comprehensively considering factors such as pore size, test section length, and water level drop rate, thereby effectively improving the accuracy and reliability of permeability calculation, thereby quickly and accurately calculating the permeability coefficient of the rock mass and obtaining accurate test results. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic diagram of the implementation flow of a rock mass permeability testing method according to an embodiment of the present invention;

[0032] Figure 2 It is a structural schematic diagram of a rock permeability testing system based on rapid water injection according to an embodiment of the present invention;

[0033] Figure 3 It is a structural schematic diagram of a rock permeability testing system based on rapid water injection according to an embodiment of the present invention;

[0034] Figure 4 It is a t-ln(s) curve representation based on the test water level of an embodiment of the present invention. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0036] like Figure 1 As shown, the embodiment of the present invention provides a rock permeability testing method, which is applied to Figure 2 The rock permeability testing system based on rapid water injection is shown.

[0037] The embodiment of the present invention first Figure 2 The rock permeability test system based on rapid water injection is briefly described as follows. Figure 2 In the present invention, the rock permeability testing system based on rapid water injection includes a drilling device, a liquid level sensor, a test tube and a data processing device. The drilling device performs construction drilling in the area to be detected in the target rock mass. After the drilling is completed, the liquid level sensor and the test tube are installed. The designated part of the borehole is the test section.

[0038] Based on this, Figure 1 The rock permeability testing method shown includes but is not limited to the following steps:

[0039] S1, the data processing device obtains the static water level in the borehole measured by the liquid level sensor;

[0040] S2. After the test pipe introduces clean water into the borehole, the data processing device obtains the test water levels measured by the liquid level sensor at n moments respectively, and calculates the water head at each moment according to the static water level in S1 and the test water level at each moment;

[0041] S3. The data processing device calculates the permeability coefficient of the target rock mass according to the dimension parameters of the borehole, the dimension parameters of the test section, the dimension parameters of the test pipe, and the water head calculated in S3 at each moment.

[0042] In the above step S2, the test water levels measured at n moments are, for example, Figure 2 The water head measured at time t0 is marked as s0, the water head measured at time t1 is marked as s1, and the water head measured at time t2 is marked as s2. The water head at each of the above moments, preferably the water head measured at a moment other than the first moment, is added to the calculation of the permeability coefficient of the target rock mass to accurately quantify the influence of the water level drop rate on the permeability coefficient.

[0043] Exemplarily, in the above step S3, the permeability coefficient of the target rock mass is calculated using the formula:

[0044]

[0045] Among them, s n According to t n The test water level recorded at the time and the static water level in S3 are obtained based on t n The water head at the moment, n = 0, 1, 2; K is the permeability coefficient, in meters per second; m is the slope of the natural logarithm of the water head and time; r1 is the diameter of the test tube, in meters; l is the length of the test section, in meters; r w is the radius of the test section, in meters.

[0046] The principle of the rock mass permeability coefficient calculation formula provided in the embodiment of the present invention is:

[0047] First, according to the Gilinsky formula for a semi-infinite aquifer:

[0048]

[0049] It can be seen that the amount of water flowing out of the upper test tube at any time is:

[0050]

[0051] Take the water head at time t1 as s1, the water head at time t2 as s2, and integrate to get:

[0052]

[0053] Arranged:

[0054] Since the permeability coefficient of the rock mass is a fixed value, the permeability coefficient calculated at any time remains unchanged. At this time, m is the slope of the natural logarithm of the head and time.

[0055] Finally, we get:

[0056] The embodiment of the present invention is implemented based on the hydrodynamic principle of rock mass. First, clean water is introduced into the borehole through a test pipe to achieve rapid water injection. Then, the water level drop process in the borehole is observed through a liquid level sensor. Based on the incomplete well formula in a semi-infinite aquifer, factors such as pore size, test section length, and water level drop rate are comprehensively considered to effectively improve the accuracy and reliability of permeability calculation, and provide a rock mass permeability coefficient calculation formula used in the above step S3. Therefore, according to the above steps S1 to S3, the permeability coefficient of the rock mass can be calculated quickly and accurately.

[0057] Another embodiment of the present invention provides another rock permeability testing method, which is also applicable to Figure 2 The rock permeability testing system based on rapid water injection shown in the figure, in another rock permeability testing method, based on Figure 1 The rock mass permeability testing method shown also includes step S4: verifying the permeability coefficient in step S3;

[0058] If the verification fails, the steps S1 to S3 are executed again, and the rate of introducing clean water into the borehole through the test pipe in S2 is adjusted.

[0059] In one embodiment, the verification method for verifying the permeability coefficient in S3 may be: verifying whether the curve of t-ln(s) is approximately a straight line, such as determining the similarity of the Y value difference of adjacent points in the curve, calculating the cosine similarity between the straight line and the curve, etc., which are not limited in the embodiment of the present invention.

[0060] It should be noted that, since the static water level is obtained before water injection, that is, before the above step S2, the water injection rate when the test tube introduces clean water into the borehole in step S2 may cause the static water level measured in step S1 to change, thereby affecting the accuracy of the permeability coefficient. Therefore, the embodiment of the present invention verifies whether the change of the static water level causes an error in the permeability coefficient through the above steps, and corrects it in time, further improving the accuracy of the measurement result.

[0061] The embodiment of the present invention also Figure 3 ,right Figure 2 The rock permeability test system based on rapid water injection is described in detail. Figure 2The rock permeability testing system based on rapid water injection includes a drilling device 21, a liquid level sensor 22, a test tube 23 and a data processing device 24. Figure 3 ,in:

[0062] The drilling device 21 is used to construct a drilling hole in the area to be detected in the target rock mass; wherein the liquid level sensor and the test tube are installed after the drilling is completed, and the designated part in the drilling hole is the test section 1;

[0063] The liquid level sensor 22 is used to measure the static water level in the borehole;

[0064] The test pipe 23 is used to introduce clean water into the borehole;

[0065] The liquid level sensor 22 is also used to measure the test water level at n moments after the test pipe introduces clean water into the borehole;

[0066] The data processing device 24 is used to calculate the water head based on each moment according to the static water level measured by the liquid level sensor and the test water level at each moment; it is also used to calculate the permeability coefficient of the target rock mass according to the size parameters of the borehole, the size parameters of the test section, the size parameters of the test pipe and the calculated water head based on each moment.

[0067] Figure 3 In the example, the size parameter of the drill hole is the drill hole diameter, which is 2r w ; The dimensional parameter of the test section is the length of the test section, which is l; the dimensional parameter of the test tube is the diameter of the test tube, which is 2r1.

[0068] For each of the above parts, the installation relationship is:

[0069] The test pipe 23 is installed in the borehole, and the liquid level sensor 22 is installed in the borehole and the test pipe 23, and below the groundwater level. The liquid level sensor 22 is installed below the groundwater level to avoid affecting the observed value during water injection.

[0070] like Figure 3 As shown, in a better implementation, the rock permeability test system based on rapid water injection also includes a water stop device 25, which is installed at the top of the test section to ensure the water stop effect, the test pipe 23 is installed in the borehole and on the water stop device 25, and the liquid level sensor 22 is installed in the borehole and the test pipe, and below the groundwater level line. Among them, the liquid level sensor 22 is installed below the groundwater level line to avoid affecting the observed value during water injection.

[0071] In a preferred implementation, a water injection device is further included, wherein the water injection device is connected to the test pipe to provide clean water to be introduced into the borehole.

[0072] The embodiment of the present invention further provides a preferred test parameter, including: the relative distance between the liquid level sensor and the groundwater level line is greater than 10 meters. Also, the single water injection time set in the water injection device is less than 1 minute, and the single water injection volume is set so that the test water level measured by the liquid level sensor at the first moment is 4 to 10 meters higher than the static water level.

[0073] The present invention also illustrates the calculation of the provided permeability coefficient through an application example:

[0074] As shown in Table 1 below, the dimensional parameters of the borehole, the dimensional parameters of the test section, the dimensional parameters of the test pipe, and the test water level measured at the first moment recorded in the above step S2, that is, the initial liquid level reading. The test water levels at subsequent moments, such as the water head s1 measured at time t1 and the water head s2 measured at time t2, are calculated by Figure 4 The ln(s)-t curve shown in the figure shows that, based on this, the permeability coefficient of the target rock mass is finally calculated to be K=0.059m / d.

[0075] Table 1 Test parameters

[0076]

[0077] The embodiment of the present invention also compares and illustrates the test result data of a water pressure test and the test result data of a water pumping test with the test result data obtained by the rock permeability test method provided in the above embodiment.

[0078] As shown in Table 2 below, a comparative analysis of the results of the rapid water injection test and the five-stage water pressure test performed by the rock permeability testing method provided by the embodiment of the present invention is shown in Table 2. 2 =0.996. As shown in Table 3 below, a comparative analysis of the results of the rapid water injection test and the 20-stage pumping test conducted by the rock permeability testing method provided by the embodiment of the present invention is shown in Table 3. 2 =0.981. The above data show that the results of the rapid water injection test, the pumping test and the water pressure test provided by the embodiment of the present invention are highly consistent, and the test results have good test accuracy.

[0079] Table 2 Comparison of rapid water injection test and water pressure test results

[0080]

[0081] Table 3 Comparison of the results of rapid water injection test and pumping test

[0082]

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A rock permeability testing method, characterized in that: The invention is applied to a rock permeability test system based on rapid water injection, wherein the rock permeability test system based on rapid water injection comprises a drilling device, a liquid level sensor, a test tube and a data processing device. The drilling device performs construction drilling in the area to be detected of the target rock mass. After the drilling is completed, the liquid level sensor and the test tube are installed. The designated part of the drilling is the test section. The rock mass permeability testing method comprises: S1: the data processing device obtains the static water level in the borehole measured by the liquid level sensor; S2: After the test pipe introduces clean water into the borehole, the data processing device obtains the test water levels measured by the liquid level sensor at n moments respectively, and calculates the water head at each moment according to the static water level in S1 and the test water level at each moment; S3: The data processing device calculates the permeability coefficient of the target rock mass according to the dimension parameters of the borehole, the dimension parameters of the test section, the dimension parameters of the test pipe and the water head calculated in S3 at each moment.

2. The rock permeability testing method according to claim 1, characterized in that: Also includes: Verifying the permeability coefficient in S3; If the verification fails, the steps S1 to S3 are executed again.

3. The rock permeability testing method according to claim 1 or 2, characterized in that: In S3, the permeability coefficient of the target rock mass is calculated using the formula: Among them, s n According to t n The test water level recorded at the time and the static water level in S3 are obtained based on t n The water head at the moment, n = 0, 1, 2; K is the permeability coefficient, in meters per second; m is the slope of the natural logarithm of the water head and time; r1 is the diameter of the test tube, in meters; l is the length of the test section, in meters; r w is the radius of the test section, in meters.

4. A rock permeability testing system based on rapid water injection, characterized in that: It includes a drilling device, a liquid level sensor, a test tube and a data processing device; The drilling device is used to construct a drilling hole in the area to be detected in the target rock mass; wherein the liquid level sensor and the test tube are installed after the drilling is completed, and the designated part in the drilling hole is the test section; The liquid level sensor is used to measure the static water level in the borehole; The test pipe is used to introduce clean water into the borehole; The liquid level sensor is also used to measure the test water level at n moments after the test pipe introduces clean water into the borehole; The data processing device is used to calculate the water head based on each moment according to the static water level measured by the liquid level sensor and the test water level at each moment; it is also used to calculate the permeability coefficient of the target rock mass according to the size parameters of the borehole, the size parameters of the test section, the size parameters of the test pipe and the calculated water head based on each moment.

5. The rock permeability testing system based on rapid water injection according to claim 4, characterized in that: The formula for calculating the permeability coefficient of the target rock mass by the data processing device is: Among them, s n According to t n The test water level recorded at the time and the static water level in S3 are obtained based on t n The water head at the moment, n = 0, 1, 2; K is the permeability coefficient, in meters per second; m is the slope of the natural logarithm of the water head and time; r1 is the diameter of the test tube, in meters; l is the length of the test section, in meters; r w is the radius of the test section, in meters.

6. The rock permeability testing system based on rapid water injection according to claim 4, characterized in that: The test pipe is installed in the borehole, and the liquid level sensor is installed in the borehole and the test pipe and is located below the groundwater level line.

7. The rock permeability testing system based on rapid water injection according to claim 4, characterized in that: It also includes a water stop device; The water-stop device is installed at the top of the test section, the test pipe is installed in the borehole and on the water-stop device, and the liquid level sensor is installed in the borehole and the test pipe and is below the groundwater level line.

8. The rock permeability testing system based on rapid water injection according to claim 6 or 7, characterized in that: The relative distance between the liquid level sensor and the groundwater level line is greater than 10 meters.

9. The rock permeability testing system based on rapid water injection according to claim 6 or 7, characterized in that: It also includes a water injection device, which is connected to the test pipe and provides clean water to be introduced into the borehole.

10. The rock permeability testing system based on rapid water injection according to claim 7, characterized in that: The single water injection time set in the water injection device is less than 1 minute, and the single water injection volume is set so that the test water level measured by the liquid level sensor at the first moment is 4 to 10 meters higher than the static water level.

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