Clamping-free water coupling rock core acoustic wave velocity testing device and method

Abstract

The invention is suitable for the technical field of geotechnical engineering investigation, and provides a clamping-free water coupling rock core sound wave velocity testing device and method.The device comprises a left sleeve, a right sleeve and a bag, and the left sleeve and the right sleeve are detachably connected; the left sleeve is a cylindrical barrel, and a first groove which extends in the axial direction and is not through is formed in the end of the left sleeve. A second groove which extends in the radial direction and is not through is formed in the side wall of the left sleeve, and a third groove which extends in the radial direction and is through is formed in the center of the bottom of the second groove; the right sleeve is a cylindrical barrel, a non-through fifth groove communicated with the first groove is formed in the end of the right sleeve, and a through sixth groove is formed in the bottom of the fifth groove; the bag is an elastic bag body with an opening in one end, and the opening of the bag is connected with the edge of the sixth groove in a sealed mode, the influence of a non-rock-core part in a sound wave propagation path on testing is eliminated, and the testing accuracy and universality are improved.

Description

Technical Field

[0001] This invention relates to the field of geotechnical engineering investigation technology, specifically a clamp-free water-coupled rock core acoustic wave velocity testing device and method. Background Technology

[0002] Core acoustic wave velocity testing is one of the important methods in the field of geophysical exploration, detection, and monitoring for engineering projects such as water conservancy, railways, and transportation. It is mainly used to determine the wave velocity of fresh, intact rock blocks of different lithologies or to study the creep law of rock block wave velocity over time. Through-sound wave propagation is currently the main method for testing core acoustic wave velocity. Existing technology mainly uses manual or equipment-clamped transducers, with the transducer and core contact surface coupled with grease, to collect data through-sound. The core wave velocity is calculated based on the length of the tested core and the time it takes for the sound wave to travel between the transmitting and receiving transducers. Although this method is widely used, it still has the following problems: (1) Fresh rock cores are taken out of the hole. The cross-section is uneven, which makes the coupling effect between the transducer and the rock core poor. It is necessary to use a cutting machine to process the cross-section. (2) The difference in coupling pressure between the transducer and the rock core contact surface can lead to significant differences in test results; (3) The sound waves radiate out from the transducer at an angle, which means that the test requires a certain length and diameter of the rock core. The test results of rock cores that do not meet the requirements are inaccurate. (4) The through-pass sampling process cannot eliminate the acoustic wave propagation time in the non-core part between the transducer and the core, which leads to a decrease in the accuracy of acoustic wave velocity testing.

[0003] Chinese patent CN208721614U discloses a rock core acoustic profiling testing system. This system features a separate design, with a support platform and a positionable testing platform as independent components. It can test rock cores of varying lengths. The transducer is fixed to a clamp, which in turn is fixed to the positionable testing platform. The positionable testing platform can move axially along the rock core tube. The support platform in the middle can also move axially along the rock core tube to facilitate the mobile measurement of the positionable testing platform, enabling full-length testing of the rock core. This patent primarily focuses on testing the wave velocity of soft seabed sand. While its design concept also involves placing the rock core inside a testing tube, the data acquisition method remains through-hole, and the testing process still requires clamping. Furthermore, the through-hole method cannot eliminate the sound wave propagation time between the transducer and the non-rock core portion, resulting in reduced accuracy in sound wave velocity testing. Therefore, this system is not ideal for solving the problem of testing rock cores in engineering exploration.

[0004] Therefore, in view of the above situation, there is an urgent need to provide a clamp-free water-coupled rock core acoustic wave velocity testing device and method to overcome the shortcomings in current practical applications. Summary of the Invention

[0005] The purpose of this invention is to provide a clamp-free water-coupled rock core acoustic wave velocity testing device and method, aiming to solve the problems in the background art mentioned above.

[0006] The present invention is implemented as follows: a clamp-free water-coupled rock core acoustic wave velocity testing device includes a left sleeve, a right sleeve and a bag, and the left sleeve and the right sleeve are detachably connected. The left sleeve is a cylindrical body, and the end of the left sleeve has an axially extending but non-through first groove. A radially extending but non-through second groove is provided on the side wall of the left sleeve, and a radially extending and through third groove is provided at the bottom center of the second groove. The right sleeve is a cylindrical body, and a non-penetrating fifth groove is opened at the end of the right sleeve, which communicates with the first groove. A penetrating sixth groove is opened at the bottom of the fifth groove. The bag is an elastic bag with an opening at one end, and the opening of the bag is sealed to the edge of the sixth groove.

[0007] As a further aspect of the present invention: the inner diameter of the second groove is larger than the outer diameter of the acoustic transducer.

[0008] As a further aspect of the present invention, the inner diameter of the third groove is smaller than the outer diameter of the acoustic transducer.

[0009] As a further aspect of the present invention: a fourth groove is provided at the end of the left sleeve, and the outer wall of the fourth groove is provided with external threads; The inner wall of the fifth groove is provided with an internal thread that connects to the external thread.

[0010] As a further aspect of the present invention, the left and right sleeves are made of nylon.

[0011] As a further aspect of the present invention, the material of the bag is rubber.

[0012] As a further aspect of the present invention: multiple second grooves are provided, and the multiple second grooves are distributed at intervals along the axial direction of the left sleeve.

[0013] As a further aspect of the present invention: the number of the third grooves is equal to the number of the second grooves.

[0014] This invention also provides a method for testing the acoustic wave velocity of water-coupled rock cores without clamping, using the aforementioned device for testing the acoustic wave velocity of water-coupled rock cores without clamping. The method includes the following steps: Step S1: Separate the left sleeve and the right sleeve, and put the rock core to be tested into the first groove from the right end of the left sleeve; Step S2: Screw the right sleeve onto the left sleeve using threads; Step S3: Keep the device horizontal, with the openings of the second and third grooves facing upwards, and inject water into the device as a coupling medium until the water overflows from the second groove. Step S4: Place the acoustic wave transmitting transducer into the first second groove from left to right, the first receiving transducer into the second second groove from left to right, and the second receiving transducer into the first third groove from left to right; so that each transducer is coupled to the rock core through water. Step S5: The transmitting transducer emits a sound wave signal, and the sound wave propagates along the "water-rock core-water" path to the receiving transducer. The initial arrival time of the sound wave is recorded. The sound wave velocity of the rock core is calculated by the distance difference between the two receiving transducers and the corresponding initial arrival time difference of the sound wave.

[0015] As a further aspect of the present invention: after step S5, step S6 is also included: changing the position of the receiving transducer and repeating steps S4-S5 multiple times with different test intervals, and finally calculating the average value of the multiple measurement results as the acoustic wave velocity of the rock core.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a clamp-free water-coupled rock core acoustic wave velocity testing device, which avoids the cutting of the rock core coupling surface, overcomes the size limitations of rock core testing, eliminates the influence of non-rock core parts in the acoustic wave propagation path on the test, and improves the accuracy and universality of the test. Attached Figure Description

[0017] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of the present invention.

[0019] Figure 2 This is a schematic diagram of the internal structure of the present invention.

[0020] Figure 3 This is a schematic diagram of the structure of the left sleeve in this invention.

[0021] Figure 4 This is a schematic diagram of the right sleeve and pouch in this invention.

[0022] In the attached diagram: 1-left sleeve, 2-right sleeve, 3-bag, 4-first groove, 5-second groove, 6-third groove, 7-fourth groove, 8-fifth groove, 9-sixth groove. Detailed Implementation

[0023] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0025] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0026] The present invention will be further explained below with reference to specific embodiments.

[0027] Please see Figures 1-4 The present invention provides a clamp-free water-coupled rock core acoustic wave velocity testing device, which includes a left sleeve 1, a right sleeve 2 and a bag 3.

[0028] The left sleeve 1 is a cylindrical nylon tube. The left sleeve 1 has a non-through first groove 4 from right to left from the center of the top right end. The left sleeve 1 has a non-through second groove 5 from top to bottom on the side wall. The bottom center of the second groove 5 has a through third groove 6 from top to bottom. The left sleeve 1 has a fourth groove 7 from right to left on the outer wall near the right end, and the outer wall of the fourth groove 7 has external threads. The right sleeve 2 is a cylindrical nylon tube. The right sleeve 2 has a non-through fifth groove 8 from left to right from the center of the left end. The inner wall of the fifth groove 8 has internal threads. The bottom of the fifth groove 8 has a through sixth groove 9 from left to right. The pouch 3 is a cylindrical rubber pouch with an opening on the left; the external thread on the outer wall of the fourth groove 7 of the left sleeve 1 is connected to the internal thread on the inner wall of the fifth groove 8 of the right sleeve 2; The left opening of the pouch 3 is sealed to the right edge of the sixth groove 9 of the right sleeve 2.

[0029] In a more specific example, the inner diameter of the second groove 5 is larger than the outer diameter of the acoustic transducer.

[0030] In a more specific example, the inner diameter of the third groove 6 is smaller than the outer diameter of the acoustic transducer.

[0031] In a more specific example, the inner diameter of the second groove 5 is larger than the inner diameter of the third groove 6, so that the acoustic transducer does not come into contact with the rock core.

[0032] In a more specific example, the left opening of the sac 3 is sealed to the right edge of the sixth groove 9 of the right sleeve 2, so that the acoustic tube has an elastic space that can extend to the right.

[0033] Please see Figures 1-4 The present invention also provides a method for testing the acoustic wave velocity of water-coupled rock cores without clamping, using the aforementioned device for testing the acoustic wave velocity of water-coupled rock cores without clamping. The method includes the following steps: Step S1: Separate the left sleeve 1 and the right sleeve 2, and put the rock core to be tested into the first groove 4 from the right end of the left sleeve 1; Step S2: Screw the right sleeve 2 onto the left sleeve 1 using threads; Step S3: Keep the device horizontal, with the openings of the second groove 5 and the third groove 6 facing upwards, and inject water into the device as a coupling medium until the water overflows from the second groove 5. Step S4: Place the acoustic wave transmitting transducer into the first second groove 5 from left to right, the first receiving transducer into the second second groove 5 from left to right, and the second receiving transducer into the third second groove 5 from left to right; so that each transducer is coupled to the rock core through water. Step S5: The transmitting transducer emits a sound wave signal, and the sound wave propagates along the "water-rock core-water" path to the receiving transducer. The initial arrival time of the sound wave is recorded. The sound wave velocity of the rock core is calculated by the distance difference between the two receiving transducers and the corresponding initial arrival time difference of the sound wave. Step S6: Change the position of the receiving transducer and repeat steps S4-S5 multiple times with different test intervals. Finally, calculate the average value of the multiple measurement results as the acoustic wave velocity of the rock core.

[0034] In summary, the working principle of this invention is as follows: Based on the principle of sound wave refraction, the transmitting transducer is placed in the first second groove 5 from left to right, the first receiving transducer is placed in the second second groove 5 from left to right, and the second receiving transducer is placed in the third second groove 5 from left to right. Each transducer is coupled to the rock core with clean water. The transmitting transducer emits a sound wave signal, and the sound wave propagates to the receiving transducer along the clean water-rock core-clean water path. Since the wave velocity of the nylon tube wall and the clean water is significantly lower than that of the rock core, the above sound wave propagation is a refracted path. Then, by using the distance difference between the receiving transducers and the time difference of the first arrival of the sound wave, the propagation time of the non-rock core part in the sound wave propagation path can be eliminated, so as to obtain a more accurate rock core wave velocity. This invention avoids the need for cutting the core coupling surface, overcomes the size limitations of core testing, eliminates the influence of non-core parts in the sound wave propagation path on the test, and improves the accuracy and universality of the test.

[0035] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A clamp-free water-coupled rock core acoustic wave velocity testing device, characterized in that, It includes a left sleeve (1), a right sleeve (2) and a pouch (3), and the left sleeve (1) and the right sleeve (2) are detachably connected; The left sleeve (1) is a cylindrical body, and the end of the left sleeve (1) is provided with an axially extending but non-through first groove (4). The left sleeve (1) has a radially extending and non-through second groove (5) on its side wall, and a radially extending and through third groove (6) is provided at the bottom center of the second groove (5). The right sleeve (2) is a cylindrical body. The end of the right sleeve (2) is provided with a non-penetrating fifth groove (8) that communicates with the first groove (4). The bottom of the fifth groove (8) is provided with a penetrating sixth groove (9). The bag (3) is an elastic bag with an opening at one end, and the opening of the bag (3) is sealed to the edge of the sixth groove (9).

2. The clamp-free water-coupled rock core acoustic wave velocity testing device according to claim 1, characterized in that, The inner diameter of the second groove (5) is larger than the outer diameter of the acoustic transducer.

3. The clamp-free water-coupled rock core acoustic wave velocity testing device according to claim 1, characterized in that, The inner diameter of the third groove (6) is smaller than the outer diameter of the acoustic transducer.

4. The clamp-free water-coupled rock core acoustic wave velocity testing device according to claim 1, characterized in that, The left sleeve (1) has a fourth groove (7) at its end, and the outer wall of the fourth groove (7) is provided with an external thread; The inner wall of the fifth groove (8) is provided with an internal thread that connects to the external thread.

5. The clamp-free water-coupled rock core acoustic wave velocity testing device according to claim 1, characterized in that, The left sleeve (1) and right sleeve (2) are made of nylon.

6. The clamp-free water-coupled rock core acoustic wave velocity testing device according to claim 1, characterized in that, The bag (3) is made of rubber.

7. The clamp-free water-coupled rock core acoustic wave velocity testing device according to any one of claims 1 to 6, characterized in that, The second groove (5) is provided in multiple ways, and the multiple second grooves (5) are distributed at intervals along the axial direction of the left sleeve (1).

8. The clamp-free water-coupled rock core acoustic wave velocity testing device according to claim 7, characterized in that, The number of the third groove (6) is equal to the number of the second groove (5).

9. A method for testing acoustic wave velocity in water-coupled rock cores without clamping, characterized in that, Using the clamp-free water-coupled rock core acoustic wave velocity testing device as described in any one of claims 1-8, the method includes the following steps: Step S1: Separate the left sleeve (1) and the right sleeve (2), and put the rock core to be tested into the first groove (4) from the right end of the left sleeve (1); Step S2: Screw the right sleeve (2) onto the left sleeve (1) using threads; Step S3: Keep the device horizontal, with the openings of the second groove (5) and the third groove (6) facing upwards, and inject water into the device as a coupling medium until the water overflows from the second groove (5); Step S4: Place the acoustic wave transmitting transducer into the first second groove (5) from left to right, the first receiving transducer into the second second groove (5) from left to right, and the second receiving transducer into the first third groove (5) from left to right; so that each transducer is coupled to the rock core through water; Step S5: The transmitting transducer emits a sound wave signal, and the sound wave propagates along the "water-rock core-water" path to the receiving transducer. The initial arrival time of the sound wave is recorded. The sound wave velocity of the rock core is calculated by the distance difference between the two receiving transducers and the corresponding initial arrival time difference of the sound wave.

10. The method according to claim 9, characterized in that, After step S5, step S6 is also included: change the position of the receiving transducer and repeat steps S4-S5 multiple times with different test intervals, and finally calculate the average value of the multiple measurement results as the acoustic wave velocity of the rock core.

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