WO2017084406A1

WO2017084406A1 - Method for fabricating three-dimensional joint-fissure cylindrical rock specimen

Info

Publication number: WO2017084406A1
Application number: PCT/CN2016/097509
Authority: WO
Inventors: 杨圣奇; 黄彦华; 田文岭
Original assignee: 中国矿业大学
Priority date: 2015-11-20
Filing date: 2016-08-31
Publication date: 2017-05-26
Also published as: CN105424435B; ZA201800237B; CN105424435A

Abstract

Provided is a method for fabricating a three-dimensional joint-fissure (1, 2, 3, 4) cylindrical rock specimen, comprising the following steps: sampling a to-be-tested engineering rock body, and cutting irregular rock masses obtained on-site at a project location into regular rectangular-cuboid-shaped rock masses; using a high-pressure water jet cutter to cut joint fissures (1, 2, 3, 4) on the regular rectangular-cuboid-shaped rock masses; using a vertical rock-coring machine to take the cores of the regular rectangular-cuboid-shaped rock masses having joint fissures (1, 2, 3, 4); using a double-end-face rock grinding machine to grind the end faces of the rock cores until smooth. The method, of the present invention, for fabricating real rock-material cylindrical standard test pieces having joint fissures (1, 2, 3, 4) and used for indoor triaxial experimentation is easy to implement, highly practicable, and accurate in positioning the joint fissures (1, 2, 3, 4), and may be widely used for fabricating rock samples having joint fissures (1, 2, 3, 4).

Description

Method for making three-dimensional jointed fracture cylindrical rock sample

Technical field

The invention relates to the field of rock engineering, in particular to a method for manufacturing a three-dimensional jointed fracture cylindrical rock sample.

Background technique

In geotechnical engineering, jointed fractured rock is a complex medium often encountered in various rock projects such as mines, water conservancy, petroleum, and nuclear waste storage. A large number of engineering practices have shown that the instability of rock engineering is usually caused by the opening, cracking, expansion and penetration of internal cracks to create new shear sliding surfaces. It is of great theoretical and practical significance to study the influence of fracture distribution on mechanical parameters such as rock strength and deformation and crack initiation, propagation and penetration modes.

The method of using indoor model materials to study fractured rock is better able to reflect the properties of rock materials. However, due to the significant heterogeneity of real materials, mineral particles, boundary effects and different degrees of cementation are difficult to rock. It is truly embodied in brittle materials. Therefore, the experimental study of prefabricated intermittent cracks in real rock materials has become an indispensable method to explore the mechanical characteristics and crack propagation process of intermittent fracture rocks. However, the current production of fractured rock samples with penetrating joints has become a difficult point to restrict the development of experimental research on jointed fracture rock mechanics. At present, the research status of related crack fabrication methods at home and abroad is as follows:

1. "Preparation of a mold with a three-dimensional cracked high-brittle transparent rock material test piece" Patent describes a method for pre-fabricating a built-in crack by embedding a mica sheet (see Patent No. CN203680625U, inventor Zhu Weishen, etc.), The method is applicable to similar model materials such as cement mortar, and is not applicable to real rock materials.

2. The method for preparing a rock-like material test piece containing a random multi-cracked body describes a method of flattening crack distribution on the surface of cement mortar before initial setting of cement mortar, piercing with metal foil of different lengths. The crack line segment on the drawing, the cement mortar is inserted vertically, and the method of pulling out the metal foil out of the prefabricated crack is taken after curing (see application No. 201110401994.4, inventor Zhao Yanlin, etc.), the method is applicable to similar model materials such as cement mortar, and is not applicable to real Rock material.

3. The method for making a random cracked rock sample describes a method for embedding a pre-formed random crack in a cement mortar material (see Patent No. 201410052815.4, inventor Yang Wendong, etc.), which is applicable to Similar model materials such as cement mortar are not suitable for real rock materials.

4. "Experimental study and numerical simulation of three-dimensional single-fracture expansion process in rock". This paper introduces a method for simulating three-dimensional built-in cracks by pre-burying thin copper sheets in unsaturated resin materials (see Journal of Coal Science 2013) No. 3, author Fu Jinwei, et al.), the method is applicable to similar model materials such as cement mortar, and is not suitable for real rock materials, and the copper sheet has a certain strength and hardness, and cannot simulate the crack.

5. "Effects of three-dimensional built-in crack angle on tensile mechanical properties and fracture characteristics of rock-like materials". This paper introduces a method for making three-dimensional built-in cracks in a rock sample embedded in a rock sample (see Journal of Rock Mechanics and Engineering). "The second issue of 2009, author Li Shucai, et al.", the method is applicable to similar model materials such as cement mortar, and the film has certain hardness and cannot effectively produce multi-fractured rock samples.

6. "Experimental study on rock failure with three-dimensional preset single crack defects" describes a method of cutting and grinding a complete cylindrical sample, using a ultrasonic drill to make a prefabricated crack, and then using two high-performance adhesives to test the two parts. A method of accurately bonding together to make a built-in crack (see Journal of Rock Mechanics and Engineering, Vol. 2, 2008, by Lin Peng, et al.), which divides the rock into two parts and then bonds it. It has destroyed the integrity of the rock sample and the influence of the binder is difficult to eliminate.

7. "Experimental investigation on strength and failure behavior of pre-cracked marble under conventional triaxial compression" describes a method for prefabricating closed fissures by cutting a rock sample with a high-speed electric cutter and filling the crack with a weak gypsum material (see "International Journal of Solids and Structures", 2008, 17 (by Yang S Q et al.), this method cuts from the surface of the rock sample to the inside, and it is impossible to cut intermittent cracks inside the rock.

8. "Experimental Study on Stress-Water Flow-Chemical Coupling of Fractured Rocks" describes a mold that is first machined in a cylindrical shape, then drilled with a drill bit, and finally a wire saw is inserted into the small hole to pre-form the crack along the mold. The method of making a pre-crack by cutting the saw back and forth (see Journal of Rock Mechanics and Engineering, 2008, 4, author Lu Zude, et al.), the hole in the process will have a hole larger than the width of the crack, and the influence of the hole It is difficult to eliminate, and the fringe of the wire saw is difficult to ensure the smoothness of the crack.

9. "Experimental Study on the Shear Strength of Sandy Clay Infilled Regular Rough Rock Joints" describes a method for pre-forming joints by first processing two molds with different undulations, pouring two rock samples separately, and bonding them together using a bonding material. (See Rock Mechanics and Rock Engineering, No. 3, 2015, by Jahanian H, et al.) This method is applicable to similar model materials such as cement mortar, and is not suitable for real rock materials, and the influence of the binder is difficult to eliminate.

Summary of the invention

In view of the current difficulty in processing a sample containing a prefabricated intermediate through-type three-dimensional jointed fracture cylindrical real rock material, the object of the present invention is to provide a method for fabricating a three-dimensional jointed fractured cylindrical rock sample, which is simple in operation and flexible according to needs. Making three-dimensional joint cracks with different geometrical parameters Gap cylindrical true rock sample.

In order to achieve the above object, the technical solution adopted by the present invention is:

A method of making a three-dimensional jointed fractured cylindrical rock sample, comprising the steps of:

(1) Sampling the engineering rock mass to be tested, and cutting the irregular rock mass obtained at the engineering site into a regular square block;

(2) cutting the joint crack on the rectangular parallelepiped rock block using a high pressure water jet;

(3) using a vertical rock corer to take the core on a rectangular block with jointed cracks;

(4) The end face of the core is smoothed by a double-faced rock grinder.

Further, the thickness of the cuboid regular rock is greater than the diameter of the final core.

Further, the high pressure waterjet cutting rock has a cutting depth greater than the diameter of the finally obtained core.

Further, the joint crack is intermittent or continuous.

Further, the jointed fracture surface is filled with a material.

Further, the joint crack includes a single crack, a parallel distributed double crack, a parallel distributed three crack, and a through joint.

The invention has the beneficial effects that the method for manufacturing the standard specimen of the solid rock material containing the joint fracture for the indoor triaxial test has the advantages of convenient operation, strong practicability, accurate joint crack positioning, and can be generally used for joint-containing joints. Preparation of fractured rock samples. After the actual test, the method proposed by the invention can prepare the joint fractured rock sample satisfying the test requirement, and can solve the problem that the model material such as cement mortar is difficult to realistically simulate the rock material, and the strength deformation characteristics of the real rock material with joint cracks are studied. And the mechanism of crack propagation and penetration has important practical significance. The invention flexibly places a high pressure water jet The cutting technology is applied to the production of three-dimensional joint fissure real rock samples. The rock sample making process is simple and fast, and according to the test requirements, the through-type three-dimensional joint fissure standard rock samples with different geometric parameters can be produced, and the corresponding indoor triaxial test is carried out. . Compared with the prior art solution, the technical solution has the following characteristics:

1) The technical method of the present invention can be applied to processing three-dimensional joint cracks on real rock;

2) The technical method of the present invention can produce a three-dimensional joint crack in the rock sample;

3) The invention can produce joint cracks of various complicated structures, and is automatically controlled by a computer to obtain accurate joint cracks, thereby obtaining more reasonable test results.

DRAWINGS

Figure 1 is a schematic view of a cuboid regular rock block obtained by cutting;

2 is a schematic view showing the cutting of the joint crack in the cuboid regular rock block;

Figure 3 is a schematic view of the core taken in a rectangular parallelepiped block containing jointed fractures;

Figure 4 is a schematic view of a fractured fractured rock sample.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings.

Example 1

Taking a granite taken from a project site as an example, a method for fabricating a three-dimensional jointed fractured cylindrical rock sample is introduced, which includes the following steps:

a. Firstly, the engineering rock mass to be tested is sampled, and the irregular rock mass obtained at the engineering site is cut into a regular square rock block. The processed rectangular parallelepiped granite stone is as shown in Fig. 1, wherein the sample has a width L of about 200 mm, a height H of about 85 mm, and a thickness W of about 50 mm;

b. Place the processed rectangular parallelepiped rock block on the “Yongda” brand high-pressure waterjet cutting machine, and cut through-type joint cracks according to the geometric parameters of the design. Cut-through joint-type cracked rectangular The body rule granite rock is shown in Figure 2, which are single crack 1, parallel distribution double crack 2, parallel distribution three crack 3 and through type joint 4;

c. Place the cut granite block with penetrating jointed cuboids on the "ZS-100" vertical rock corer, and take out the sample of the through-type jointed fractured cylindrical granite. A sample of a cylindrical granite having a through-type jointed fracture is shown in Fig. 3, wherein the core has a diameter of 38 mm and a height of 85 mm;

d. Place the sample of the through-type jointed cracked cylindrical granite on the "SHM-200" double-faced rock grinder to smooth the ends of the core. The through-type jointed cracked cylindrical granite sample with smooth end surface is shown in Fig. 4, wherein the core has a diameter of 38 mm and a height of 76 mm.

The thickness of the cuboid regular rock mass (50mm) should be greater than the diameter of the final core (38mm).

The high pressure water jet can cut the rock and the cutting depth (50mm) should be greater than the diameter of the final core (38mm).

Wherein, the joint fissure obtained in step b may be intermittent or continuous, and the joint fissure surface may not be filled with materials, and may also be filled with weak materials such as mica and gypsum.

The above description is only a preferred embodiment of the present invention, and it should be noted that those skilled in the art can also make several improvements and retouchings without departing from the principles of the present invention. It should be considered as the scope of protection of the present invention.

Claims

A method for manufacturing a three-dimensional jointed fractured cylindrical rock sample, comprising: the following steps:

(1) Sampling the engineering rock mass to be tested, and cutting the irregular rock mass obtained at the engineering site into a regular square block;

(2) cutting the joint crack on the rectangular parallelepiped rock block using a high pressure water jet;

(3) using a vertical rock corer to take the core on a rectangular block with jointed cracks;

(4) The end face of the core is smoothed by a double-faced rock grinder.
A method of making a three-dimensional jointed fractured cylindrical rock sample according to claim 1, wherein said cuboid regular rock mass has a thickness greater than a diameter of the final core.
A method of making a three-dimensional jointed fractured cylindrical rock sample according to claim 1, wherein said high pressure water jet cutting rock has a cutting depth greater than a diameter of the finally obtained core.
A method of making a three-dimensional jointed fractured cylindrical rock sample according to claim 1, wherein said joint crack is intermittent or continuous.
A method of making a three-dimensional jointed fractured cylindrical rock sample according to claim 1, wherein said jointed fracture surface is filled with a material.
The method for manufacturing a three-dimensional jointed fractured cylindrical rock sample according to claim 5, wherein the material of the joint fracture surface is mica and gypsum.
The method of fabricating a three-dimensional jointed fractured cylindrical rock sample according to claim 1, wherein the joint fracture comprises a single fracture, a parallel distribution double fracture, a parallel distribution three fracture, and a through joint.