CN-122016593-A - Device and method for determining critical fracture opening degree of slurry injection

CN122016593ACN 122016593 ACN122016593 ACN 122016593ACN-122016593-A

Abstract

The invention discloses a device and a method for determining critical fracture opening degree of slurry injection, wherein the device integrates high-precision mechanical driving, customized fracture model and real-time dynamic observation function, and realizes accurate continuous adjustment of fracture opening degree through continuous propulsion of a stepping motor. The device is based on a transparent crack model structure which is internally narrow and externally expanded when deformed, reduces the seepage resistance of slurry, supports the visual observation of the seepage and diffusion process of slurry in cracks, synchronously monitors the change of grouting pressure and crack opening in the test, and when the grouting pressure is rapidly increased, the corresponding opening is the critical crack opening, thereby realizing the integrated test from crack opening regulation and control, slurry migration visualization to critical parameter quantitative analysis. The device has simple structure and convenient operation, and provides an effective means for the injectability evaluation and process optimization of geotechnical engineering grouting materials.

Inventors

XIE SHIPING
LI BINGXU
QIAN ZIWEI
YANG ZHU
LI YANGMING
TENG LONG
ZHENG HAOBO
ZHU CHENGMIN
LIU JUFENG
Pu Xiwen

Assignees

长沙矿山研究院有限责任公司
中国矿业大学

Dates

Publication Date: 20260512
Application Date: 20251229

Claims (10)

1. The device for determining the critical fracture opening degree of the slurry is characterized by comprising a test model frame (6), wherein the test model frame (6) comprises a first support and a second support which are arranged up and down, a stepping motor (1) is arranged on the first support, a bearing platform (9) is arranged on the second support, a prefabricated fracture model (10) is arranged on the bearing platform (9), the prefabricated fracture model (10) is an integrated transparent disc, The prefabricated crack model (10) comprises a crack upper plate (25) and a crack lower plate (16), a plurality of supporting cushion feet (17) are fixedly arranged on the upper surface of the crack lower plate (16), the crack upper plate (25) is arranged on the supporting cushion feet (17), a crack (21) is formed between the crack upper plate (25) and the crack lower plate (16), a slurry buffer bin (15) is formed at the center, the slurry buffer bin (15) is communicated with the crack (21), the end part of the crack (21) is communicated with a slurry leakage slit (20), a grouting inlet (18) is formed at the center of the crack lower plate (16), one end of the grouting inlet (18) is communicated with the slurry buffer bin (15), and the other end of the grouting inlet is connected with a grouting pipe (11) through a grouting interface (24), The tail end of a pushing rod (7) of the stepping motor (1) is propped against the upper surface of the crack upper plate (25), a fixed guide sleeve (5) is sleeved outside the pushing rod (7), a displacement meter fixing frame (12) is arranged on the second support, a displacement meter (13) is arranged on the displacement meter fixing frame (12), and a probe head of the displacement meter (13) is vertically arranged on the upper surface of the crack upper plate (25) and corresponds to the position of the crack inlet (19).
2. An apparatus for determining critical fracture opening for slurry injection according to claim 1, wherein the fracture upper plate (25) has controllable micro-amplitude deformability.
3. A device for determining the critical fracture opening degree for slurry injection according to claim 1, wherein a gasket (8) is arranged between the pushing rod (7) and the fracture upper plate (25).
4. A device for determining the critical fracture opening degree for slurry injection according to claim 3, wherein: the supporting foot pad (17) is a telescopic foot pad.
5. A method of determining a critical fracture opening degree for slurry injectivity based on the apparatus of claim 4, comprising the steps of: s1, assembling a device; s2, determining the corresponding relation between the propulsion quantity and the opening; S3, constructing a grouting system; S4, grouting and opening adjustment; S5, determining the critical opening of the slurry to be measured.
6. The method according to claim 5, wherein the specific process of the step S1 is that the upper slit plate (25) is covered on the lower slit plate (16), so that the upper slit plate (25) is completely attached to the upper surface of the supporting pad leg (17) of the lower slit plate (16); The method comprises the steps of installing a stepping motor (1) on a first support of a test model frame (6), installing a bearing platform (9) on a second support of the test model frame (6), fixedly arranging a prefabricated crack model (10) on the bearing platform (9), enabling the tail end of a pushing rod (7) of the stepping motor (1) to be abutted against a gasket (8) at the central position of a crack upper plate (25), installing a displacement meter (13) on a displacement meter fixing frame (12) so that a probe head of the displacement meter (13) vertically contacts the upper surface of the crack upper plate (25) and corresponds to the position of a crack inlet (19) in the vertical direction, and finally connecting a stepping motor power line (2) and a displacement meter power line (14).
7. The method according to claim 5, wherein the specific process of the step S2 is to calibrate the corresponding relation between the initial crack opening corresponding to the height of the initial support foot (17) and the propulsion amount of the stepping motor (1) and estimate the critical crack opening reference value for grouting.
8. The method according to claim 5, characterized in that the grouting system comprises a grouting pump, a grouting pipe (11) and a grouting pressure monitoring system for injecting the grouting liquid into the slurry surge bin (15) in the prefabricated fracture model (10) while monitoring the grouting pressure.
9. The method according to claim 8, wherein the concrete process of the step S4 is that a grouting pump is started to grouting into the crack (21), grouting pressure is monitored in the whole process, meanwhile, the stepping motor (1) is controlled to slowly and uniformly push, the center of the crack upper plate (25) is pressed by the pushing rod (7), the crack inlet upper edge (22) is gradually close to the crack inlet lower edge (23), and the continuous and smooth reduction of the opening of the crack inlet (19) is realized.
10. The method according to claim 9, wherein the concrete process of the step S5 is that grouting pressure data are monitored in real time, when grouting pressure is increased sharply, the grouting pressure indicates that slurry is blocked at a crack inlet (19), and at the moment, the vertical distance between the upper edge (22) and the lower edge (23) of the crack inlet is the critical crack opening of the slurry to be detected, which can be injected into the corresponding crack.

Description

Device and method for determining critical fracture opening degree of slurry injection Technical Field The invention belongs to the technical field of fractured rock mass grouting, and particularly relates to a device and a method for determining critical fracture opening degree of slurry injection. Background The injectability of the slurry in the fracture is an important basis for performing grouting design, particularly when particle suspension type slurry is injected, such as typical cement slurry, clay slurry, and the like. The slurry is a solid-liquid two-phase mixed fluid, and the solid phase of the slurry is solid particles with certain granularity. When the opening degree of the cracks is smaller than the critical opening degree, solid particles in the slurry can block the cracks, so that the slurry cannot be injected. The critical fracture opening degree of the slurry which can be injected in the fracture is critical, which is an important basis for the selection of grouting materials and the determination of a grouting process in the grouting design, and the grouting effect is concerned, even the success or failure is achieved. According to the related study, the slurry is not injectible in the cracks, and the slurry solid phase particle size is not simply caused by exceeding the opening degree of the cracks, but the multiparticulates perform bridging action in the cracks. It has been theorized that the injection is only possible when the fracture opening is greater than 3 times the size of the slurry solid phase particles. There have been studies (Wangkai, wang Lianguo, liu Yinlong, et al visual test study of cement slurry percolation effect in microcracks [ J ]. Coal journal 2020,45 (03): 990-997) of preparing cracks of different opening degrees by laying stainless steel gaskets of different thickness between two experimental plates, and obtaining the critical crack opening degrees for different types of slurry to be injected through experiments. The invention patent CN104266936A adopts the prefabricated fracture with diamond-shaped section, realizes the continuous change of the fracture opening, and correspondingly determines the critical fracture opening of the slurry injection by the fracture opening at the periphery of the grouting diffusion. In this method, slurry diffusion is affected by the injected section, and the slurry diffusion is stopped at a certain position, possibly not reaching the critical fracture opening. In addition, the invention patents CN118583727a and CN111504872a enable continuous variation of the fracture opening, but the formed fracture is a straight fracture. When the slurry experiments concerned are carried out, the stop of slurry diffusion is often not caused by the fact that the opening is smaller than the injectible critical opening, and is mostly influenced by seepage resistance caused by slurry diffusion, so that the problem of injectible caused by the change of crack opening cannot be truly reflected Disclosure of Invention Aiming at the technical problems, the invention provides a device and a method for determining the critical fracture opening degree of grouting liquid, which provide an effective means for the injectability evaluation and process optimization of geotechnical engineering grouting materials. The invention provides a device for determining critical crack opening degree of slurry injection, which comprises a test model frame, wherein the test model frame comprises a first bracket and a second bracket which are arranged up and down, a stepping motor is arranged on the first bracket, a bearing platform is arranged on the second bracket, a prefabricated crack model is arranged on the bearing platform, the prefabricated crack model is an integrated transparent disc, The prefabricated crack model comprises a crack upper plate and a crack lower plate, wherein the upper surface of the crack lower plate is fixedly provided with a plurality of supporting pad feet, the crack upper plate is arranged on the supporting pad feet, a crack is formed between the crack upper plate and the crack lower plate, a slurry buffer bin is formed in the center of the crack upper plate and is communicated with the crack, the end part of the crack is communicated with a slurry leakage slot, a grouting inlet is formed in the center of the crack lower plate, one end of the grouting inlet is communicated with the slurry buffer bin, the other end of the grouting inlet is connected with a grouting pipe through a grouting interface, The tail end of the pushing rod of the stepping motor is abutted against the upper surface of the crack upper plate, a fixed guide sleeve is sleeved outside the pushing rod, a displacement meter fixing frame is arranged on the second support, a displacement meter is arranged on the displacement meter fixing frame, and a probe head of the displacement meter is vertically arranged on the upper surface of the crack upper plate and corresponds to the pos