Method for simulating three-dimensional closed and clung cracks in rocks

Abstract

The invention provides a method for simulating three-dimensional closed and clung cracks in rocks. The method comprises the following steps: taking a complete transparent material, and selecting a position and a range of precast cracks in the transparent material; focusing laser to the position through a lens; in a focusing process, enabling the position to generate a cracking point when laser energy exceeds a damage threshold value of the material; repeating the process, focusing the laser at the periphery of the cracking point and generating one group of cracking points; continuously inputting the laser energy, and simultaneously enabling the generated cracking points to be subjected to continual damage expansion and connecting the cracking points to form a cracking surface; meanwhile, along with the input of the energy, continually carrying out the damage expansion on an outward edge of the cracking point at the outermost periphery to form one circle of crack expansion region (annular surface) to be connected with the cracking surface; forming the three-dimensional closed and clung cracks at the position of the precast cracks, and keeping an original shape of other parts of the transparent material. The method provided by the invention is reasonable and is rapid and efficient; other surplus cracks are not formed, and edges are ordered; a test piece is complete and is not damaged; the property of the test piece is close to that of a rock material, and the simulation degree is high.

Description

technical field [0001] The invention belongs to the technical field of rock engineering damage prediction and safety, and relates to a method for simulating a three-dimensional closed and close crack inside a rock. Background technique [0002] The problem of rock fracture is a basic problem in the engineering field. For example, large-scale rock fractures will cause earthquakes; internal cracks in rocks will expand until they are destroyed, which will cause disastrous consequences such as water conservancy, traffic tunnel collapse, and side slope landslides, threatening the safety of people's lives and properties. Therefore, the law of rock propagation and failure with cracks has always been an important issue concerned by the engineering community. [0003] Material cracks can be divided into three categories according to the location of occurrence: three-dimensional closed cracks (also known as deep cracks), surface cracks and through cracks. [0004] The definition of i...

AI Technical Summary

Problems solved by technology

However, there are many deficiencies in the pouring method as follows: 1) Insufficient simulation process: the crack making process is complex and time-consuming. The manufacturing process includes mold making, prefabricated crack making, mixed liquid making, and repeated baking and freezing of solidified specimens. , high cost and low efficiency; 2) Insufficient brittleness: the maximum brittleness of the transparent material prepared by pouring method can only reach about 1 / 7-1 / 8, while the average brittleness of different rocks is about 1 / 10, some rocks 3) Insufficient test conditions: the pouring method requires a low temperature environment to achieve, and the test conditions are demanding; 4) Insufficient cracks: the pouring method uses metal sheets or mica sheets as prefabricated cracks, not really no thickness cracks , insufficient simulation; 5) insufficient transparency

Adams M (Crack extension from flaws in a brittlematerial subjected to compression [J]. Tctonophysics) et al. used this method to make internal three-dimensional closed cracks, but the cut-and-paste method has the following shortcomings: 1) Insufficient simulation process: the crack creation process is complicated, It takes a long time to cut the surface of the PMMA plate or glass, and then paste the two cut glasses to form a transparent material with prefabricated cracks, which is quite different from the simulation process and the actual rock crack process, and the simulation is low; 2 ) Insufficient brittleness: The brittleness of the transparent material prepared by the cutting-pasting method can only reach about 1 / 3 at most, while the average brittleness of different rocks is about 1 / 10, and the brittleness of some rocks can be as high as 1 / 20; 3) Insufficient cracks: the prefabricated cracks of the cutting-pasting method are formed by cutting with a knife, not cracks that are close to the real crack surface; 4) Insufficient integrity of the test piece: the sample is bonded by glue and is not a homogeneous object

However, in fact, glass 3D printing was successfully realized, and there was no substantial breakthrough until 2017, and it was published in the world's top journal "Nature" (2017, volume 44, doi:10.1038 / nature22061). For the use of 3D printing technology to make interior 3D cracks, this technology has not yet been implemented

At the same time, the 3D printing method has the following disadvantages: 1) 3D printing technology needs to heat the quartz sand to 1600-1800°C to melt, which requires high equipment, complicated technology and operation; 2) 3D printing has high application costs and is not suitable for large-scale Popularization and application; 3) The homogeneity and transparency of materials prepared by 3D printing are not high; 4) The relevant patents of 3D printing technology only realize the production of transparent rock mass, how to further make cracks include internal three-dimensional closed cracks, surface cracks and through cracks no information yet

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