Three-point bending test study on the propagation law of internal cracks and failure characteristics of brittle solids based on 3D-ILC technology#br#
WANG Haijun1，LI Hanzhang1，2，REN Ran3，TANG Lei1，YU Shuyang1，2，ZHANG Zhitao1
(1. State Key Laboratory of Hydrology-Water Resource and Hydraulic Engineering，Nanjing Hydraulic Research Institute，Nanjing，Jiangsu 210029，China；2. College of Water Conservancy and Hydropower Engineering，Hohai University，Nanjing，Jiangsu 210098，China；3. Shenzhen Water Group，Shenzhen，Guangdong 518031，China)
Abstract：Crack propagation in rocks is one of the important issues in geotechnical engineering. Based on 3D-ILC technology，an ideal brittle material is selected，and the actual internal crack with arbitrary parameter is generated without affecting the surface of the sample. The three-point bending test of ideal brittle material samples containing actual random internal cracks generated without changing the sample surface was carried out and compared with the complete samples. Failure process，characteristic load，failure mode，fracture characteristics，dynamic bifurcation and stress moire were analyzed，and the K-distribution and extension path of the crack tip were obtained by numerical simulation. The results show that the cracking and breaking loads of the specimen are reduced greatly due to the existence of internal cracks，and that the internal crack tip presents petal-like strain moire which can be monitored by the stress birefringence technology combined with 3D-ILC. Under three-point bending，the blank specimens occur dynamic fractures with atomization，feather zone characteristics caused by dynamic crack bifurcation，while the crack-containing specimens gradually crack from the lower tip to the upper tip of the internal crack of a pure type–I failure in a drop-like shape with characteristics of the intersection Wallner line. It is also indicated that both the K-distribution at the crack tip based on M-integral and MTS-based internal crack propagation path simulation are consistent with the test results. Compared with the current mainstream methods in the study of transparent rock，3D-ILC has certain advancement in brittleness，crack authenticity，stress field visualization and fracture characteristics. The test and numerical simulation results will provide experimental and theoretical references for research on problems including internal crack propagation and three-dimensional fracture of brittle materials such as rock.
王海军1，李汉章1，2，任 然3，汤 雷1，郁舒阳1，2，张志韬1. 基于3D-ILC三点弯脆性固体内裂纹扩展规律及破坏特征研究[J]. 岩石力学与工程学报, 2019, 38(12): 2463-2477.
WANG Haijun1，LI Hanzhang1，2，REN Ran3，TANG Lei1，YU Shuyang1，2，ZHANG Zhitao1. Three-point bending test study on the propagation law of internal cracks and failure characteristics of brittle solids based on 3D-ILC technology#br#. , 2019, 38(12): 2463-2477.
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2019, Vol. 38 
