Study on the Crack Growth Law and Mechanism of the Rock Mass with Defect Combination
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ORIGINAL PAPER
Study on the Crack Growth Law and Mechanism of the Rock Mass with Defect Combination Weihong Yang
. Baozhen Wei . Yadong Xu
Received: 28 June 2020 / Accepted: 5 September 2020 Ó Springer Nature Switzerland AG 2020
Abstract There are different defect combinations in natural rock mass. In the process of underground engineering excavation, the existence of defect combination poses a serious threat to the construction safety. In this paper, the uniaxial compression test of red sandstone with prefabricated defects combination angles of 15°, 30°, 45°, 60° and 90° was conducted by Shimadzu universal testing machine respectively, and the crack propagation law and mechanism of red sandstone with different defects are studied, The test results showed that the red sandstone with different angle defects only produced tensile cracks, there had not shear cracks, and finally resulted in tensile failure. This was due to the existence of defects combination which weakened the local stress concentration and releases part of energy in advance. With the increasing of the defect combination angle, the weakening degree of stress concentration increased, and the uniaxial compressive strength of the specimen decreased as a whole, and with 45° as the boundary. There was an
W. Yang Y. Xu State Key Laboratory of Mining Disaster Prevention and Control Co-Founded by Shandong Provence and the Ministry of Science and Technology, Shandong University of Science and Technology, Qingdao 266590, China B. Wei (&) Dongtan Coal Mine of Yanzhou Coal Co. LTD, Jining 237500, China e-mail: [email protected]
obvious strength area division, and the failure time of the specimen was obviously prolonged, furthermore, the brittle failure characteristics of specimens are obviously weakened. The test results have important guiding significance and reference value for the construction design in the field of underground engineering. Keywords Prefabricated defect combination Crack propagation Different angles Stress concentration
1 Introduction In recent years, with the rapid development of social economy, the problem of underground engineering disturbance has attracted much attention. As we all know, there are a lot of cracks, holes and other defects in the natural rock mass, which pose a serious threat to the safe operation of coal mines, tunnels and other projects. For this reason, it is of great practical significance and reference value to carry out research on natural rock defects. For the problems of rock defects, scholars at home and abroad had conducted a lot of researches. Based on the discrete element model (GBM), Saadat and Taheri (2019) explored the effect of grain size on the cracks response of pre-cracked granite. Lee and Jeon (2011) presented crack initiation, propagation and
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Geotech Geol Eng
coalescence at or near pre-existing open cracks or flaws in specimens which were different materials under uniaxial compression and verified by PFC2D numerical simulation. Liu et
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