Multi-purpose pressurized water connection test method

Abstract

The present invention discloses a multi-purpose pressure water connectivity test method. It includes the following steps: Step 1: Designating a specific observation line; Step 2: Arranging pressure water boreholes and observation boreholes; Step 3: Determining the location of the pressure water test section of the pressure water borehole; Step 4: Conducting the pressure water test; Step 5: Simultaneously observing the water level in the observation borehole during the pressure water test; Step 6: Compiling the test data and plotting a graph of the relationship between the pressure in the pressure water borehole test section, the water level in the observation borehole, and time. This method has the advantages of being able to conduct a connectivity test simultaneously with the pressure water test and to identify the characteristics of the pressure water in the rock mass while measuring rock mass permeability parameters.

Description

Technical Field

[0001] The present invention relates to the field of water conservancy and hydropower engineering investigation, and more specifically, it is a multi-purpose water pressure connection test method. More specifically, it is a multi-purpose method which combines a water pressure test with a connection test based on the regularity of structural surface development, anisotropy of permeability and pressure transmission effect to achieve the determination of rock permeability parameters and the identification of the occurrence state of pressurized water in the rock mass and hydraulic connection. Background Art

[0002] In the construction of water conservancy and hydropower projects, anti-seepage treatment is crucial to the ability of reservoirs to store water and effectively utilize it, and the safety of dam seepage. Various structural surfaces exist in rock masses, and their engineering properties and permeability characteristics are anisotropic. Therefore, a reasonable anti-seepage support layer should be selected for reservoir and dam foundation anti-seepage. Excessive anti-seepage depth will result in a waste of project investment, while too small a depth will fail to block the leakage channel, leaving safety issues. Some rock masses also contain pressurized water. The rock mass in areas where pressurized water is stored has relatively high permeability. In addition to causing leakage problems, the pressure of the pressurized water may also be detrimental to the stability of the foundations of water-retaining structures such as dams. Therefore, identifying the permeability characteristics of the rock mass and the state and hydraulic connections of groundwater, especially pressurized water, has become an important task in geological surveys for water conservancy and hydropower projects.

[0003] To evaluate the permeability characteristics of rock masses, borehole water pressure tests are currently commonly used. This method measures permeability by recording the relationship between test section pressure and inflow rate. Specific procedures are specified in relevant standards and are mature. To assess the hydraulic connectivity of groundwater, connectivity tests are currently commonly performed, primarily employing methods such as indicator placement, water injection, and hole plugging. However, these connectivity tests are only suitable for areas with good channel connectivity, particularly karst areas, and are less effective and less effective in low-permeability, non-karst areas. Water pressure tests and connectivity tests are conducted independently, and connectivity tests are generally not considered in non-karst areas. However, in engineering practice, water pressure tests are performed continuously throughout the drilling process. If groundwater, particularly confined water, is revealed during drilling, water pressure tests are performed solely on the borehole to determine the permeability of the rock mass. Failure to utilize the borehole to identify its hydraulic connectivity or fully utilize other aspects of its function can lead to wasted resources and inefficient exploration. Summary of the Invention

[0004] The purpose of the present invention is to provide a multi-purpose water pressure connectivity test method, which is a method for conducting a connectivity test simultaneously with a water pressure test. This method can realize the determination of rock permeability parameters and the identification of the rock mass pressure water storage state, hydraulic connection and other multi-purposes, and has the advantages of reliable technology, convenient operation and improved work efficiency.

[0005] In order to achieve the above object, the technical solution of the present invention is: a multi-purpose pressure water connection test method, characterized in that it includes the following steps:

[0006] Step 1: Design a specific observation line;

[0007] Step 2: Arrange water pressure drilling holes and observation drilling holes;

[0008] Step 3: Determine the location of the water-pressure test section of the water-pressure drilling hole;

[0009] Step 4: Conduct water pressure test;

[0010] Step 5: Observe the borehole water level simultaneously during the water pressure test;

[0011] Step 6: Organize the test data and draw a curve of the relationship between the pressure of the water-pressure drilling test section, the observed borehole water level and time.

[0012] In the above technical solution, in step 1, the specific observation line is the line connecting the water pressure borehole and the observation borehole, which is drawn up based on the development trend and status of the main structural surface. The line connecting the water pressure borehole and the observation borehole is the observation line. The observation line cannot be arranged arbitrarily but should be a specific observation line drawn up based on the development trend and status of the main structural surface. The number of observation lines should not be less than the number of main structural surface groups, and the direction of the observation line should be equivalent to the direction of the main structural surface.

[0013] At the project site, systematically collect the direction, dip, inclination, and filling characteristics of each structural surface, and compile a structural surface direction rose diagram. The rose diagram can reflect the development level of the structural surface. The most developed structural surface is the main structural surface in the project area. When the main structural surfaces of a certain direction are closed or have dense fillings, this group of main structural surfaces has weak permeability and is unlikely to contain groundwater or have hydraulic connection with other groundwater. This group of main structural surfaces can be ignored when arranging observation lines. When the main structural surfaces of a certain direction have strong permeability, this group of main structural surfaces contains groundwater or has hydraulic connection with other groundwater, and it is the main structural surface that should be considered when arranging observation lines.

[0014] According to the above principles, Figure 1 According to the rose diagram of the structural surface trend, two groups of main structural surfaces are developed, and the first and second observation lines are arranged accordingly (such as Figure 2 The directions of these two observation lines are consistent with the trends of the two main structural surfaces, and the angles between them are both θ (unit: degree).

[0015] In the above technical solution, in step 2, there are multiple specific observation lines; the water pressure drilling hole is set at the intersection of the multiple specific observation lines;

[0016] The water pressure boreholes and observation boreholes are located on specific observation lines, and 1 to 3 observation boreholes are arranged on each specific observation line (such as Figure 2 shown);

[0017] The distance between observation boreholes and pressure water boreholes should be determined based on factors such as the bedrock geological structure, rock permeability, and groundwater characteristics. The spacing between adjacent boreholes (i.e., the spacing between adjacent pressure water boreholes and observation boreholes, or the spacing between two adjacent pressure water boreholes) should generally be less than 50 meters. The diameter of pressure water boreholes should preferably be 75 mm or 91 mm. Diamond or alloy drilling should be used for drilling, and clean water can be used as the flushing fluid. Mud and other wall protection materials should not be used.

[0018] The depth of the pressure water drilling is controlled to be 5 meters below the confined aquifer to ensure that the entire water-bearing area is exposed, and the drilling depth is observed to reveal the confined water;

[0019] According to the above principles, Figure 2 The intersection of the first observation line and the second observation line is the water pressure borehole YK0. Two observation boreholes are arranged on the first observation line, namely: GK1-1 and GK1-2; two observation boreholes are arranged on the second observation line, namely: GK2-1 and GK2-2.

[0020] In the above technical solution, in step 3, the pressure water plug of the working pipe is placed from top to bottom at the exposed part of the pressure water, and the position of the pressure water test section of the pressure water drilling hole is further determined by observing the water level changes inside and outside the working pipe (such as Figure 3 shown).

[0021] In the above technical solution, before the working pipe is placed, the pressurized water flows out from the orifice of the drill hole (i.e., the pressure water drill hole, such as YK0). After the working pipe is placed, the pressurized water flows out from the working pipe due to the water blocking effect of the plug, and the water level outside the working pipe is the static water level (such as Figure 3 a);

[0022] Move the plug down gradually until water flows both inside and outside the working tube (e.g. Figure 3 b), the top plate of the test section can be determined;

[0023] The plug is moved downwards until water flows out of the working tube and the water level in the working tube is at a static level (e.g. Figure 3 c), the bottom plate of the test section can be determined;

[0024] The water pressure test uses a working pipe with double plugs, and the upper and lower plugs are placed on the top and bottom plates of the determined test section respectively (such as Figure 3 d), the hole section between the two plugs is the pressurized water storage space (i.e. the exposed part of the pressurized water), which serves as the test section for the water pressure test.

[0025] In the above technical solution, in step 4, a water pressure test of the pressure water test section is carried out in the water pressure drill hole in accordance with the requirements of the current relevant technical standards. The test is carried out at three levels of pressure and five stages (P1-P2-P3-P2-P1). P1, P2, and P3 are the test section pressures, which are generally 0.3 MPa, 0.6 MPa, and 1.0 MPa, respectively.

[0026] After placing the working pipe and isolating the test section with a double plug, observe the water level in the working pipe and use the stable water level line in the working pipe as the zero line for pressure calculation; place the pressure gauge at the orifice of the borehole (i.e., water pressure borehole, such as YK0). If the zero line for pressure calculation is h meters higher than the orifice, then during the water pressure test, the pressure gauge readings for the test section pressures P1, P2, and P3 are (0.01h+P1) MPa, (0.01h+P2) MPa, and (0.01h+P3) MPa, respectively, and measure the corresponding flow rate (in liters / minute).

[0027] In the above technical solution, in step five, when conducting the water pressure test, the water pressure drilling test section is applied with pressures of different sizes, which may cause changes in the observed borehole water level. The borehole water level should be observed simultaneously during the water pressure test; corresponding to the five stages of the water pressure test, the observation time interval of each borehole water level in each stage is 1 to 5 minutes; when the water level changes greatly, the time interval is shorter, and when the water level changes slightly, the time interval is longer, until the observed borehole water level remains stable.

[0028] In the above technical solution, in step 6, the relevant data obtained during the test are sorted out, the water permeability of the pressure water test section is calculated, and a curve diagram of the relationship between the pressure of the pressure water drilling test section, the observed borehole water level and time is drawn (such as Figure 4 According to the water permeability, the permeability characteristics of the confined water storage area can be evaluated; according to the pressure of the water-pressure drilling test section, the observed borehole water level and time relationship curve, the confined water storage state and hydraulic connection in each borehole (i.e., water-pressure drilling, such as YK0) can be evaluated.

[0029] The present invention provides a multi-purpose pressure water connection test method, which has the following beneficial effects:

[0030] (1) The present invention can simultaneously carry out a connectivity test when conducting a water pressure test and identify the characteristics of rock mass pressure water when measuring rock mass permeability parameters. The water pressure test utilizes existing mature technology, and the connectivity test is based on the principle of pressure transmission. The mechanism of action is clear and definite, and the test results are accurate and reliable.

[0031] (2) Combine the water pressure test with the connectivity test to achieve multiple uses of one hole, convenient operation, and improve the efficiency of the survey work. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1This is a rose diagram showing the direction of the multi-purpose pressure water connection test structure in an embodiment of the present invention.

[0033] Figure 2 This is a plan layout diagram of the specific observation line, water pressure borehole, and observation borehole for the multi-purpose water pressure connection test in an embodiment of the present invention.

[0034] Figure 3 This is a diagram of the process of determining the position of the pressure water test section of the multi-purpose pressure water connection test pressure water drilling hole in an embodiment of the present invention.

[0035] Figure 4 This is a graph showing the relationship between the pressure of the water pressure drilling test section, the observed borehole water level and time in a multi-purpose water pressure connection test in an embodiment of the present invention.

[0036] Figure 5 It is a process flow chart of the present invention.

[0037] exist Figure 1 、 Figure 2 In the equation, ① and ② are the numbers of two specific observation lines, which are also the numbers of two main structural surfaces with different strikes. ① represents the number of the first specific observation line; ② represents the number of the second specific observation line. θ is the acute angle between the first specific observation line ① and the second specific observation line ②, which is also the acute angle between the strikes of the main structural surfaces.

[0038] exist Figure 2 In the figure, YK0 is the water pressure borehole number; GK1-1 is the observation borehole number No. 1 on the first specific observation line, GK1-2 is the observation borehole number No. 2 on the first specific observation line; GK2-1 is the observation borehole number No. 1 on the second specific observation line, and GK2-2 is the observation borehole number No. 2 on the second specific observation line.

[0039] exist Figure 3 In the figure, a shows the working state diagram when the pressurized water flows out of the working pipe after the working pipe is placed in the borehole; b shows the working state diagram when the plug of the working pipe is moved down to determine the top plate of the water pressure test section; c shows the working state diagram when the plug of the working pipe is moved down to determine the bottom plate of the water pressure test section; d shows the working state diagram when a working pipe with double plugs is placed in the borehole (i.e., water pressure borehole YK0).

[0040] Figure 4 In the figure, the solid line is the relationship curve between the pressure of the water pressure drilling test section and time, the dotted line is the relationship curve between the water level of each observation borehole and time, P1, P2, and P3 are the pressures of the first, second, and third stage test sections of the water pressure, YK0 is the number of the water pressure drilling hole, GK1-1 is the number of the observation borehole No. 1 on the first specific observation line, GK1-2 is the number of the observation borehole No. 2 on the first specific observation line, GK2-1 is the number of the observation borehole No. 1 on the second specific observation line, and GK2-2 is the number of the observation borehole No. 2 on the second specific observation line.

[0041] In the figure, 1-borehole, 2-working pipe, 3-plug, 4-water level outside the working pipe, 5-water level inside the working pipe, 6-confined water storage space, 7-groundwater flow direction. DETAILED DESCRIPTION

[0042] The following detailed description of the embodiments of the present invention is given in conjunction with the accompanying drawings, which do not limit the present invention but are merely examples. The description makes the advantages of the present invention clearer and easier to understand.

[0043] The present invention carries out a connectivity test at the same time as the water pressure test, determines the rock permeability parameters (i.e., water permeability) through the water pressure connectivity test, and analyzes and evaluates the rock mass pressure water storage state and hydraulic connection based on the data and charts compiled from the water pressure connectivity test; during the test process of the present invention, the water pressure test is carried out according to the current relevant standard procedures with high accuracy; in the connectivity test carried out at the same time, the test principle is to utilize the pressure transmission effect, and after engineering inspection, the test results are reliable and accurate.

[0044] Example

[0045] The present invention is now described in detail by taking the application of the present invention to a preliminary geological survey project of a certain water conservancy hub and its supporting irrigation area project as an example, which also has a guiding role in the application of the present invention to other engineering survey projects.

[0046] In the early stage of the project, bedrock pressurized water was one of the main engineering geological problems, and it was believed that the pressurized water would be detrimental to the stability of the dam.

[0047] The multi-purpose pressure water connection test method of this embodiment is as follows: Figure 5 As shown, the following steps are included:

[0048] Step 1: Design a specific observation line;

[0049] At the project site, the direction, inclination, dip angle, filling material characteristics of each structural surface were systematically collected. The structural surface is mainly cracks. One group is the slab cracks with steep dip angles, straight crack surfaces, and slightly open. The other group is the cracks that intersect the slab at a large angle and are generally closed. The structural surface direction rose diagram (such as Figure 1 As shown in Figure 1, two main structural planes can be seen: the first group of cracks strikes 315 degrees (plate cracks), the second group of cracks strikes 36 degrees (cracks intersecting the plate at a large angle), and the acute angle θ between the two main structural planes is 81 degrees. The first and second specific observation lines are arranged, and the directions of the observation lines are consistent with the strikes of the two main structural planes (as shown in Figure 1). Figure 1 、 Figure 2 shown).

[0050] Step 2: Arrange water pressure drilling and observation drilling;

[0051] The intersection of the first and second observation lines is the water pressure borehole YK0. Two observation boreholes are arranged on each observation line. The first observation line is arranged with observation boreholes GK1-1 and GK1-2, and the second observation line is arranged with observation boreholes GK2-1 and GK2-2 (such as Figure 2 The spacing between boreholes is generally less than 50 meters, including 20 meters between boreholes YK0 and GK1-1, 30 meters between boreholes GK1-1 and GK1-2, 25 meters between boreholes YK0 and GK2-1, and 45 meters between boreholes YK2-1 and GK2-2. The borehole diameter (including water-jet boreholes and observation boreholes) is 75 to 91 mm. The lithology is slate, which is relatively soft. The boreholes (including water-jet boreholes and observation boreholes) are drilled with alloy and flushed with clean water. The water-jet borehole is 45.2 meters deep, with the bottom of the hole 5 meters below the confined aquifer. The remaining observation boreholes are 35.7 to 44.6 meters deep, and all reveal confined water.

[0052] Step 3: Determine the location of the water-pressure test section of the water-pressure drilling hole;

[0053] Place the pressure water plug of the working pipe from top to bottom at the exposed part of the pressure water, and further determine the position of the pressure water test section of the pressure water drilling hole by observing the water level changes inside and outside the working pipe (such as Figure 3 The top and bottom plate depths of the test section were determined to be 37.3 meters and 40.2 meters respectively. A working pipe with double plugs was used for the water pressure test. The upper and lower plugs were placed at the determined top and bottom plates respectively. The hole section between the two plugs was the exposed part of the pressurized water and served as the test section for the water pressure test. The test section was 2.9 meters long.

[0054] Step 4: Conduct water pressure test;

[0055] In accordance with the requirements of current relevant technical standards, a water pressure test of the pressurized water test section is carried out in the water pressure borehole; the test is carried out at three levels of pressure and five stages (P1-P2-P3-P2-P1), with P1, P2, and P3 being the test section pressures, with values ​​of 0.3 MPa, 0.6 MPa, and 1.0 MPa, respectively; after placing the working pipe and isolating the test section with a double plug, the water level in the working pipe is observed, and the stable water level of the pressurized water is 11.2 meters above the orifice. The stable water level line in the working pipe is used as the zero line for pressure calculation; a pressure gauge is placed at the orifice of the borehole (i.e., water pressure borehole YK0), and the zero line for pressure calculation is 11.2 meters above the orifice. During the water pressure test, the pressure gauge readings corresponding to the test section pressures P1, P2, and P3 are 0.4 MPa, 0.7 MPa, and 1.1 MPa, respectively, and the corresponding flow rates (in liters / minute) are measured.

[0056] Step 5: Observe the borehole water level simultaneously during the water pressure test;

[0057] Corresponding to the five stages of the water pressure test, the observation time interval for the water level of each observation borehole in each stage is 1 to 5 minutes. The shorter the time interval is when the water level fluctuation is large, and the longer the time interval is when the water level fluctuation is small, until the water level of the observation borehole remains stable. The water pressure connection test starts at 16:10 and ends at 18:10, lasting 120 minutes, of which the water pressure test lasts 50 minutes. After the water pressure test is completed, the observation of the change process of the water level in the observation borehole will continue.

[0058] Step 6: Organize the test data and draw a graph showing the relationship between the pressure of the water-pressure drilling test section, the observed borehole water level and time;

[0059] The relevant data obtained during the test were sorted out, the water permeability of the pressure water test section was calculated, and a curve of the relationship between the pressure of the pressure water drilling test section, the observed borehole water level and time was drawn (such as Figure 4 As shown); according to the test section length of 2.9 meters, when P3 = 1.0 MPa, the corresponding flow rate is 68.7 liters / minute, and the permeability of the test section rock mass is calculated to be 23.7 Lu Rong, which is medium permeability; during the test, the maximum increase of the water level of the observation boreholes GK1-1 and GK1-2 on the first observation line was 4.2 meters and 2.3 meters respectively, and the water level of the observation boreholes GK2-1 and GK2-2 on the second observation line remained basically unchanged, indicating that the confined water revealed by the boreholes on the first observation line has hydraulic connection, while the confined water revealed by the boreholes on the second observation line has no hydraulic connection.

[0060] The multi-purpose pressurized water connection test method described in the present invention has been successfully tried out in the early geological survey of a water conservancy hub and supporting irrigation area project in a certain place in this embodiment. In this embodiment, the bedrock confined water at the dam site is one of the main engineering geological problems. The early survey believed that the confined water would be detrimental to the stability of the dam. The design accordingly adopted measures such as grouting and sealing the confined aquifer and decompressing the pressure relief tank. In the preliminary design stage of this embodiment, a variety of survey methods including the multi-purpose pressurized water connection test described in the present invention were adopted to find out the properties, distribution and burial conditions, water level, flow rate, and hydraulic connection of the confined water. It was believed that the confined water in the dam foundation rock mass had basically no adverse effect on the stability of the dam. Based on this, the design cancelled the dam foundation pressure relief tank facility, optimized the curtain grouting plan, and saved about 3.2 million yuan in foundation treatment costs.

[0061] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

[0062] The contents not described in detail in this specification belong to the prior art known to those skilled in the art.

Claims

1. A multi-purpose pressure water connection test method, characterized in that: The following steps are included: Step 1: Design a specific observation line; Step 2: Arrange water pressure drilling holes and observation drilling holes; Step 3: Determine the location of the water-pressure test section of the water-pressure drilling hole; Step 4: Conduct water pressure test; Step 5: Observe the borehole water level simultaneously during the water pressure test; Step 6: Organize the test data and draw a graph showing the relationship between the pressure of the water-pressure drilling test section, the observed borehole water level and time; In step 1, the specific observation line is the line connecting the water pressure borehole and the observation borehole, which is drawn up based on the development trend and status of the main structural surface; When the permeability of a certain group of main structural surfaces is high, this group of main structural surfaces contains groundwater or is hydraulically connected with other groundwater, and is considered as the main structural surface when arranging the observation line; In step 2, there are multiple specific observation lines; the water pressure drilling hole is set at the intersection of the multiple specific observation lines; Both the water pressure boreholes and observation boreholes are located on specific observation lines, with 1 to 3 observation boreholes arranged on each specific observation line.

2. The multi-purpose pressure water connection test method according to claim 1, characterized in that: In step 2, the depth of the water-pressure drilling is controlled to be 5 meters below the confined aquifer, and the drilling depth is observed to reveal the confined water.

3. The multi-purpose pressure water connection test method according to claim 2, characterized in that: In step three, the plug (3) of the working pipe (2) is placed from top to bottom at the exposed part of the pressurized water, and the position of the pressurized water test section of the water-pressure drilling hole is further determined by observing the water level changes inside and outside the working pipe.

4. The multi-purpose pressure water connection test method according to claim 3, characterized in that: Before the working pipe (2) is placed, pressurized water flows out from the orifice of the borehole (1). After the working pipe (2) is placed, due to the water blocking effect of the plug (3), the pressurized water flows out from the working pipe (2), and the water level (4) outside the working pipe becomes the static water level. The plug is gradually moved downwards, and when water flows both inside and outside the working pipe (2), the top plate of the test section is determined; The plug is further moved downwards. When water flow appears outside the working pipe (2) and the water level (5) inside the working pipe is at a static level, the bottom plate of the test section is determined. The water pressure test uses a working pipe with double plugs. The upper and lower plugs are placed on the top and bottom plates of the determined test section respectively. The hole section between the two plugs is the pressurized water storage space (6) and serves as the test section for the water pressure test.

5. The multi-purpose pressure water connection test method according to claim 4, characterized in that: In step 4, a water pressure test is carried out in the water pressure borehole at the water pressure test section. The test is carried out at three pressure levels and five stages. P1, P2, and P3 are the test section pressures, which are 0.3 MPa, 0.6 MPa, and 1.0 MPa, respectively. After placing a working pipe (2) and isolating the test section with a double plug, the water level in the working pipe is observed, and the stable water level line in the working pipe is used as the pressure calculation zero line; a pressure gauge is placed at the borehole orifice, and when the pressure calculation zero line is h meters higher than the orifice, during the water pressure test, the pressure gauge readings corresponding to the test section pressures P1, P2, and P3 are (0.01h+P1) MPa, (0.01h+P2) MPa, and (0.01h+P3) MPa, respectively, and the corresponding flow rates are measured.

6. The multi-purpose pressure water connection test method according to claim 5, characterized in that: In step five, while conducting the water pressure test, the borehole water level is observed simultaneously; corresponding to the five stages of the water pressure test, the observation time interval of each borehole water level in each stage is 1 to 5 minutes, until the borehole water level is continuously stable.

7. The multi-purpose pressure water connection test method according to claim 6, characterized in that: In step six, the relevant data obtained during the test are sorted out, the permeability of the pressure water test section is calculated, and a curve diagram of the relationship between the pressure of the pressure water drilling test section, the observed borehole water level and time is drawn.

Images