Preparation method of multi-angle oblique-crossing jointed rock mass sample containing JRC roughness

Abstract

The invention provides a preparation method of a multi-angle oblique-crossing jointed rock mass sample containing JRC roughness, belongs to the field of rock mechanics, and aims to solve the problem that the existing method cannot solve the problems of research on mechanical properties of rough and multi-angle oblique-crossing jointed rock mass and the like. The method comprises a bottom plate, long side plates, short side plates, joint models and fixing bolts, according to the occurrence relation of two joints in a skew joint rock mass, multi-angle transformation of the skew joint is achieved through design of the position and angle of a bottom plate mounting groove, and meanwhile, according to the roughness coefficient of the joints, 10 sets of JRC joint models are prepared to represent the roughness degree of the skew joint. The multi-angle oblique-crossing jointed rock mass sample containing JRC roughness prepared by the method provides a new thought for research on mechanical properties of rocks.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of rock mechanics, and particularly relates to a preparation method of a multi-angle oblique joint rock mass sample containing JRC roughness. BACKGROUND

[0002] Rock mass is continuously affected by temperature, moisture, chemical solution, tectonic movement, weathering and denudation and other factors during formation, and small fracture joint structures with different roughness and micro relative displacement are generated inside; due to the existence of joints, the rock mass not only embodies heterogeneity, discontinuity and anisotropy, but also has significant changes in physical and mechanical properties; the instability and rupture of the rock mass usually begin with its internal original defects, and the cracking, opening, sliding, expansion and penetration of the joints are important forms leading to the destruction of the rock mass. The joints in natural rock mass usually exist in groups and are oblique, compared with single or parallel joints, the multi-angle oblique joints are more universal, and the joint surfaces in natural rock mass are not smooth but contain a certain roughness, which seriously affects the shear strength and deformation properties of the joints; under the action of engineering disturbance, due to the roughness of the joints, the rock mass first shears and slides along the joints, and the multi-angle oblique joints are easy to form crack propagation, thereby leading to the penetration of the rock mass, therefore, it is of great significance to the development of rock mechanics to study the mechanical properties of rough, multi-angle oblique joint rock mass.

[0003] So far, many experts and scholars have proposed various methods for preparing joint rock mass samples to study the mechanical properties of joint rock mass.

[0004] A Chinese invention patent with publication number CN120141976A discloses a non-continuous joint rock mass similar material block model sample preparation mold and method, and provides an eight-step sample preparation method of a non-continuous jointed rock mass similar material model in line with test requirements. However, there are the following deficiencies in the preparation process: (1) the joint model is in a fixed mode and cannot be adjusted according to the actual geological occurrence environment; (2) the roughness of the joint is not considered in the joint model, and the influence factors such as joint shear strength are ignored.

[0005] A Chinese invention patent with publication number CN115993272B discloses a joint rock mass sample preparation method based on three-dimensional scanning and 3D printing, and provides a method for simulating the preparation of a joint rock mass sample containing filling material by acquiring the spatial relative position of the joint rock mass fracture through a handheld three-dimensional scanner, reconstructing a three-dimensional model and representing the joint fracture condition according to the partition condition by using different particle size printing materials, but the similarity problem between the printing material and the rock mass material is not considered in the preparation process.

[0006] A three-dimensional jointed rock mass modeling method with different roughness and connectivity is disclosed in Chinese invention patent CN120124157A, which provides a jointed rock mass modeling method for freely controlling the spatial distribution characteristics of joint surfaces, and considers the roughness and connectivity of joints on this basis. However, there are the following shortcomings in the production process: (1) It is limited to the establishment of numerical models and cannot be used to make test molds; (2) The roughness of the joints cannot be quantitatively described and lacks relevance to natural joints.

[0007] Chinese invention patent CN119935682A discloses a mold for making rock-like specimens containing filled joint surfaces and a use method, which provides a method for making rock-like specimens containing filled joint surfaces with coplanar or non-coplanar relationship, but does not consider the distribution characteristics of joint oblique intersection and the difference in joint angle during the production process.

[0008] Through the above analysis, the existing methods for making jointed rock mass specimens all have certain defects, and how to accurately and reasonably make jointed rock mass specimens with different roughness and multi-angle oblique joints has become a key problem to be solved in the current research on jointed rock mass. SUMMARY

[0009] To solve this problem, the present application provides a multi-angle oblique jointed rock mass specimen preparation method containing JRC roughness. The present application includes a bottom plate with pre-drilled bolt holes and multi-angle oblique joint installation grooves, an L-shaped long side plate, a movable short side plate, a joint model containing JRC roughness and installation grooves, and fixed bolts. According to the occurrence relationship of two joints in the oblique jointed rock mass, the position and angle of the installation groove on the bottom plate are designed to realize multi-angle transformation of the oblique joint, and 10 groups of JRC joint models are prepared according to the joint roughness coefficient to represent the roughness of the oblique joint, thereby preparing a multi-angle oblique jointed rock mass specimen containing JRC roughness, and providing a new idea for rock mechanics performance research.

[0010] To achieve the above purpose, the present application adopts the following technical solutions to solve it.

[0011] A multi-angle oblique jointed rock mass specimen preparation method containing JRC roughness, comprising the following steps: Step 1: According to the occurrence relationship of two joints in the oblique jointed rock mass, the specific position of the oblique joint on the bottom plate is determined; based on the length, width and angle parameters of the two joints, installation grooves are made on the bottom plate, and the angle of the installation grooves can also be designed to realize multi-angle transformation of the oblique joint.

[0012] Step 2: Assemble the L-shaped long side plate, according to the reserved holes at the same position of the base plate and the L-shaped long side plate, connect them by bolts to form a whole; the movable short side plate is bolted to the base plate and the L-shaped long side plate to form a cube structure with only one opening, and the size of the rock mass sample can be changed by moving the short side plate.

[0013] Step 3: In order to characterize the roughness of the oblique joint, according to the joint roughness coefficient, 2 groups of 10 standard JRC joint models are prepared, the joint roughness remains unchanged in the joint through direction, and the installation convex groove at the bottom of the joint is made to adapt to the installation groove of the base plate to fix the oblique joint.

[0014] Step 4: According to the similarity ratio criterion of oblique joint rock mass, the uniformly mixed rock-like material is filled into the hollow area of the model, the insert vibrator is used for tamping, and after natural curing to the standard requirement, the bolt connection is released to prepare a multi-angle oblique joint rock mass sample containing JRC roughness.

[0015] Further, the length, width and depth of the base plate mounting groove in step 1 are half of the joint length, joint width and base plate thickness respectively, and the oblique joint angle can be designed as 0°, 30°, 45°, 60°, 90°, 120°, 135°, 150° and 180°, 210°, 225°, 240°, 270°, 300°, 315°, 330°.

[0016] Further, in step 2, the number and spacing of bolts of the L-shaped long side plate, the base plate and the movable short side plate should be set to form a whole, and the movable short side plate can change the size of the rock mass sample, but the oblique joint rock mass sample still needs to meet the Saint-Venant principle.

[0017] Further, in step 3, the two joints can be set with the same JRC joint model, or with different JRC joint models, or with smooth joint model, and the length, width and height of the joint bottom installation convex groove are half of the joint length, joint width and base plate thickness respectively.

[0018] Further, in step 4, the uniformly mixed rock-like material is vibrated until the surface appears to have floating slurry, no significant subsidence and no air bubbles, the curing time is 28d, and the joint model also needs to be removed after the bolt connection is released, to prepare a multi-angle oblique joint rock mass sample containing JRC roughness without filling.

[0019] Compared with the prior art, the present application has the beneficial effects that a preparation method of a multi-angle oblique joint rock mass sample containing JRC roughness is provided. Through the design of the position and angle of the bottom plate mounting groove, multi-angle transformation of the oblique joint is realized, and 10 groups of JRC joint models are prepared to represent the roughness of the oblique joint, which has the advantages of being close to the actual situation and simple to make, and provides a new method for studying the mechanical properties of rough and multi-angle oblique joint rock mass. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is a whole structure diagram of the preparation method of the multi-angle oblique joint rock mass sample containing JRC roughness.

[0021] Figure 2 It is a bottom plate with reserved bolt holes and multi-angle oblique joint mounting grooves.

[0022] Figure 3 It is an L-shaped long side plate.

[0023] Figure 4 It is a movable short side plate.

[0024] Figure 5 It is a joint roughness coefficient and JRC joint model comparison diagram.

[0025] Figure 6 It is a first standard JRC joint model with mounting grooves.

[0026] Figure 7 It is a smooth joint model with mounting grooves.

[0027] Figure 8 It is a fixed bolt. DETAILED DESCRIPTION

[0028] The embodiments of the present application will be described clearly, completely and in detail below in combination with the drawings and specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0029] The whole structure of the preparation method of the multi-angle oblique joint rock mass sample containing JRC roughness provided by the embodiments of the present application is as shown in Figure 1 The method comprises the following steps: Step 1: The occurrence relationship of the two joints in the oblique jointed rock mass is that the two joints are both through joints and remain unchanged in the through direction, and the centers of the two joints are on the same horizontal line with a spacing of 300 mm; the parameters of the two joints are also the same, and the length, width and angle are 100 mm, 5 mm and 45° respectively. A bottom plate with a size of length 800 mm, width 600 mm and thickness 10 mm is prepared, and the oblique joint is arranged in the middle of the bottom plate, and a mounting groove with a depth of 5 mm is made; in order to realize the multi-angle transformation of the oblique joint, the angle of the mounting groove is designed as 0°, 30°, 60°, 90°, 120°, 135°, 150° and 180°, 210°, 225°, 240°, 270°, 300°, 315° and 330°, as shown in Figure 2 .

[0030] Step 2: As shown in Figure 3 , the length of the L-shaped long side plate is consistent with the length of the bottom plate, which is 800 mm, and the width and height are 100 mm and 200 mm respectively; when assembling the L-shaped long side plate, 5 holes are reserved at the same position of the bottom plate and the L-shaped long side plate, and the holes are connected by bolts as shown in Figure 8 ; the number and spacing of the bolts should be set so that they form a whole. As shown in Figure 4 , the length of the movable short side plate is 400 mm, and the width and height are consistent with those of the L-shaped long side plate, which are 100 mm and 200 mm respectively; the movable short side plate is also connected with the bottom plate and the L-shaped long side plate by bolts to form a cube structure with only one open side, and the size of the rock mass sample can be changed by moving the short side plate, but the oblique jointed rock mass sample still needs to meet the Saint-Venant principle.

[0031] Step 3: In order to characterize the roughness of the oblique joint, according to the joint roughness coefficient and the JRC joint model comparison relationship as shown in Figure 5 , 2 groups of 10 standard JRC joint models are prepared, and the joint roughness remains unchanged in the joint through direction; the two joints can be set with the same JRC joint model, or with different JRC joint models, Figure 6 the first standard JRC joint model, or a smooth joint model, as shown in Figure 7 ; Figure 6 and Figure 7 the joint model bottom is made with a mounting convex groove, and the length, width and height of the mounting convex groove are matched with the length, width and depth of the mounting groove of the bottom plate, which is used to fix the oblique joint.

[0032] Step 4: According to the similar ratio criterion of the oblique joint rock mass, the mixed and uniform rock-like material is filled into the hollow area of the model, and is tamped by using the inserted vibrator until the surface presents the floating slurry, no significant subsidence and no air bubbles come out; after natural curing for 28 days, the joint model is removed by releasing the bolt connection, and the multi-angle oblique joint rock mass sample without filling and containing JRC roughness is prepared.

[0033] The above specific embodiments are used to explain the content, scheme and beneficial effects of the present application, and are not used to limit the present application. Any change, modification, replacement, combination, simplification, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing multi-angle oblique jointed rock mass specimens including JRC roughness, characterized in that, It includes a base plate, long side plates, short side plates, joint models, and fixing bolts; the base plate includes pre-drilled bolt holes and multi-angle oblique joint mounting grooves; the long side plates are L-shaped; the short side plates are movable; the joint models include JRC roughness and mounting protrusions; The process includes the following steps: Step 1: Based on the occurrence relationship of two joints in the obliquely jointed rock mass, determine the specific location of the oblique joint on the base plate; based on the length, width, and angle parameters of the two joints, create installation grooves on the base plate. The angle of the installation grooves can also be designed to achieve multi-angle transformation of the oblique joint; Step 2: Assemble the L-shaped long side plate. Connect the base plate and the L-shaped long side plate with bolts to form a whole, according to the pre-reserved holes at the same positions; the movable short side plate is bolted to both the base plate and the L-shaped long side plate, forming a cubic structure with only one open side. Simultaneously, moving the short side plate can change... Rock mass sample size; Step 3: In order to characterize the roughness of the oblique joints, based on the joint roughness coefficient, two sets of 10 standard JRC joint models were prepared. The joint roughness remained unchanged in the joint penetration direction. At the same time, an installation groove adapted to the mounting groove of the base plate was made at the bottom of the joint to fix the oblique joints; Step 4: According to the similarity ratio criterion of the oblique joint rock mass, the uniformly mixed rock mass-like material was loaded into the hollow area of ​​the model and compacted using an immersion vibrator. After natural curing to the standard requirements, the bolt connection was removed to prepare a multi-angle oblique joint rock mass sample containing JRC roughness.

2. The method for preparing a multi-angle oblique jointed rock mass sample including JRC roughness according to claim 1, characterized in that, The length, width, and depth of the mounting groove on the base plate are respectively the joint length, joint width, and half the thickness of the base plate. The angles of the oblique joints can be designed as 0°, 30°, 45°, 60°, 90°, 120°, 135°, 150°, 180°, 210°, 225°, 240°, 270°, 300°, 315°, and 330°.

3. The method for preparing a multi-angle oblique jointed rock mass sample including JRC roughness according to claim 1, characterized in that, The number and spacing of bolts on the L-shaped long side plate, bottom plate, and movable short side plate should be set up to form a whole. Although the movable short side plate can change the size of the rock mass sample, the oblique jointed rock mass sample still needs to meet the Saint-Venant principle.

4. The method for preparing a multi-angle oblique jointed rock mass sample including JRC roughness according to claim 1, characterized in that, Two joints can be set with the same JRC joint model, or different JRC joint models, or a smooth joint model. The length, width, and height of the groove installed at the bottom of the joint are half the joint length, half the joint width, and half the thickness of the base plate, respectively.

5. The method for preparing a multi-angle oblique jointed rock mass sample including JRC roughness according to claim 1, characterized in that, The uniformly mixed rock mass material should be vibrated until the surface shows a floating slurry, no longer sinks significantly, and no bubbles emerge. The curing time is 28 days. After the bolt connection is removed, the joint model also needs to be taken out to prepare a multi-angle oblique joint rock mass sample without filling and containing JRC roughness.

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