Experimental and numerical study on strength and deformation behaviors of sandstone with intersecting flaws

Fei Xiong, Xinrong Liu, Guangyi Lin, Xiaohan Zhou, Dongshuang Liu, Bin Xu, Yafeng Han, Chunmei He and Zijuan Wang

Abstract

The distribution pattern of flaws has a significant impact on the mechanical behavior of the rock. To understand the cracking mechanism of the rock with intersecting flaws, the cracking behavior of sandstone containing two intersecting flaws under uniaxial compression was investigated through laboratory tests and particle ﬂow code (PFC2D). The strength and failure characteristics of sandstone with intersecting flaws were studied. Subsequently, the evolution of the stress fields and displacement fields were analyzed, and the cracking mechanism of intersecting flaws was discussed. The results showed that the peak stress and average modulus decrease with increasing intersecting angle α of intersecting flaws in both experiments and numerical simulation. The experimental peak stress shows an increasing tendency, while the experimental average modulus first increases and then decreases with increasing direction angle β, which is slightly different from simulation results. The cracking mode of the intersecting flaws was determined by angles α and β. Specifically, when α and β were small, the main fracture surfaces formed at the inner and outer tips of one flaw. When α and β were large, the main fracture surfaces formed at the outer tips of the two flaws. The variation in the high tensile stress zone with α and β is the essential reason for the change in cracking modes with α and β. In addition, a new type of displacement field (defined as DF_IV) related to crack initiation was found. In this type of displacement field, the displacement difference is the main cause of cracking.

Key Words

damage evolution; displacement field; intersecting flaws; PFC2D; sandstone; stress field

Address

Fei Xiong: 1.)School of Civil Engineering, Chongqing University, Chongqing 400045, China 2.) State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China Xinrong Li and Xiaohan Zhou: 1.) School of Civil Engineering, Chongqing University, Chongqing 400045, China 2.) State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, China 3.) National Joint Engineering Research Center of Geohazards Prevention in The Reservoir Areas,Chongqing University, Chongqing 400045, China Dongshuang Liu, Bin Xu, Yafeng Han: School of Civil Engineering, Chongqing University, Chongqing 400045, China Chunmei He: College of Architectural Engineering, Neijiang Normal University, Neijiang 641100, China Zijuan Wang: School of Management Science and Engineering, Chongqing Technology and Business University, Chongqing 400067, China

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