CN-121994696-A - Device and method for testing normal cementing strength of rock mass structural plane

CN121994696ACN 121994696 ACN121994696 ACN 121994696ACN-121994696-A

Abstract

The invention belongs to the technical field of rock mechanics, and discloses a device and a method for testing normal cementing strength of a rock mass structural surface, wherein the device comprises an upper clamping assembly and a lower clamping assembly which are used for fixing two ends of a rock sample, wherein the clamping assembly comprises a filling type self-adaptive clamping head provided with a cavity, and the cavity can be used for forming a shape-preserving base which is completely matched with an irregular surface of the end part of the rock sample through injecting a curable filling material; the self-leveling connecting assembly is connected between the clamping assembly and the testing machine and used for eliminating eccentric moment, and the real-time strain monitoring system is arranged on the side wall of the rock sample and used for monitoring stress uniformity in the loading process. Through the structure, the invention solves the technical problems of difficult clamping, low centering precision and uncontrollable damage position of the rock sample with the structural surface, and can accurately and reliably perform a normal pull-out test on the irregular structural surface so as to obtain the cementing strength or cohesive force of the irregular structural surface.

Inventors

ZHU XUANHUA
ZHENG HAOZE
LUO CHENG
YAN FUHENG

Assignees

四川农业大学

Dates

Publication Date: 20260508
Application Date: 20260313

Claims (10)

1. Testing arrangement of rock mass structural plane normal cementing strength, characterized in that includes: the upper clamping assembly and the lower clamping assembly are used for respectively fixing two ends of a rock sample containing a rock mass structural surface; The clamping assembly comprises a filling type self-adaptive clamping head, wherein the filling type self-adaptive clamping head is provided with a cavity for accommodating the end part of the rock sample and an injection opening for injecting a curable filling material, and the curable filling material forms a conformal base matched with the irregular surface of the end part of the rock sample after being cured; the self-leveling connecting assembly is connected between the clamping assembly and the testing machine and is used for eliminating eccentric moment in the loading process; and the real-time strain monitoring system is arranged on the side wall of the rock sample and is used for monitoring the uniformity of stress born by the rock sample in the loading process.
2. The experimental set-up of claim 1, wherein the curable filler material is a low melting point alloy or a high strength non-shrink grouting material.
3. The experimental set-up of claim 1, wherein the self-leveling connection assembly comprises at least one spherical hinge or gimbal structure.
4. The experimental device of claim 1, wherein the real-time strain monitoring system comprises at least three strain gages uniformly distributed along the circumference of the rock sample, a data acquisition module electrically connected with the strain gages, and a display terminal for displaying real-time data of each strain gage.
5. The apparatus of claim 1, further comprising a reinforcing sleeve disposed about the periphery of the non-test area of the rock sample, the reinforcing sleeve configured to increase the tensile strength of the non-test area to ensure that normal pull-apart failure occurs at the target rock mass structural face.
6. The experimental set of claim 5, wherein the reinforcement sleeve is a carbon fiber composite layer or a removable metal ferrule.
7. A method for testing normal cementing strength of a rock mass structural plane by using the experimental device according to any one of claims 1-6, comprising the following steps: s1, preparing a rock sample containing a rock mass structural surface to be measured; S2, respectively placing two ends of the rock sample into cavities of the filling type self-adaptive clamping heads for positioning; S3, injecting a liquid curable filling material into the cavity through an injection port, and fixing the rock sample and the filling type self-adaptive clamping head into a whole after curing the curable filling material; S4, installing a real-time strain monitoring system on the side wall of the rock sample, and installing a clamping assembly on a testing machine through a self-leveling connecting assembly; And S5, starting the testing machine to apply normal tensile load, monitoring stress uniformity of the rock sample through the real-time strain monitoring system until the rock sample is pulled apart to be damaged along the structural surface of the target rock mass, and recording the damage load.
8. The method of claim 7, further comprising, after step S2 and before step S3, disposing a reinforcing sleeve around the outer periphery of the non-test area of the rock sample.
9. The method according to claim 7, wherein in step S5, the installation position of the rock sample is finely adjusted by the strain data fed back by the real-time strain monitoring system until the difference of the strain values of the monitoring points is smaller than a preset threshold value before formal loading.
10. The method according to claim 7, wherein in step S3, the injected curable filler material is a low melting point alloy in a molten state, and is cooled and solidified after the injection.

Description

Device and method for testing normal cementing strength of rock mass structural plane Technical Field The invention belongs to the technical field of rock mechanics, and particularly relates to a device and a method for testing normal cementing strength of a rock mass structural plane. Background Rock mass structural planes (such as joints, layers, faults and the like) are key factors for controlling the mechanical behavior of rock mass engineering. The normal cementing strength (or normal cohesive force), namely the capability of resisting the breaking in the direction vertical to the structural surface, is a key parameter for evaluating the integrity of the rock mass, carrying out fine numerical simulation (such as discrete element analysis) and evaluating special engineering problems such as hydraulic fracturing, high-level waste disposal warehouse long-term stability and the like. In conventional geotechnical engineering design, this value is often reduced to zero for safety. However, this simplification ignores the objectively existing, albeit weak, but vital cementing of the structural face due to mineral filling, partial healing, etc., resulting in too conservative or distorted predictions of rock mass behaviour. At present, the test method for accurately acquiring the parameter is extremely deficient, mainly because the normal pull-apart test of an irregular rock sample containing a natural structural surface faces a great challenge: 1. The clamping difficulty and stress concentration are that the columnar joint surface is natural and irregular, and the traditional mode of bonding the adhesive such as epoxy resin and the like with the plane clamp is difficult to ensure the uniformity of the adhesive layer, so that the stress concentration is easily caused on the joint surface, and the measured strength value is low and unreliable. 2. The centering accuracy is low, the test requires that the tensile force is strictly applied along the axis of the rock sample, and any eccentricity can introduce bending moment, so that the rock sample is damaged in advance. The existing centering mode depends on static centering, and cannot verify centering effect in real time in the loading process. 3. The failure location is not controllable-tensile failure may occur at other weak points inside the rock sample due to the heterogeneity of the rock material, rather than on the expected columnar joint surfaces, causing the test to fail. Disclosure of Invention The invention aims to solve the problem that the strength parameter cannot be accurately obtained due to irregular structural surface, difficult centering, uncontrollable damage position and the like in the prior art at least to a certain extent. Therefore, the invention aims to provide a device and a method for testing the normal cementing strength of a rock mass structural plane. The technical scheme adopted by the invention is as follows: On one hand, the invention provides a testing device for normal cementing strength of a rock mass structural surface, which comprises an upper clamping assembly and a lower clamping assembly, wherein the clamping assemblies comprise a filling type self-adaptive clamping head, the filling type self-adaptive clamping head is provided with a cavity for accommodating a rock sample end part and an injection port for injecting a curable filling material, the curable filling material forms a conformal base matched with an irregular surface of the rock sample end part after being cured, the testing device further comprises a self-leveling connecting assembly connected between the clamping assemblies and a testing machine, and a real-time strain monitoring system arranged on the side wall of the rock sample. As a preferred solution, the curable filler material is a low melting point alloy or a high strength non-shrink grouting material, which has good fluidity, high strength after curing, and good adhesion to rock, and can effectively transfer tensile force. As a preferred solution, the self-levelling connection assembly comprises at least one spherical hinge or gimbal structure which provides a plurality of rotational degrees of freedom, automatically compensating for angular deviations generated during installation, ensuring pure axial loading. As a preferable scheme, the real-time strain monitoring system comprises at least three strain gauges uniformly distributed along the circumference of the rock sample, a data acquisition module and a display terminal. By comparing the strain of each point in real time, whether the eccentric tension exists or not can be intuitively and quantitatively judged. As a preferred option, the experimental set-up further comprises a reinforcing sleeve arranged at the periphery of the non-test area of the rock sample. The sleeve is used for reinforcing the non-test area, so that the target joint structural surface is artificially the weakest link in the whole stress system. As a preferable scheme, the re