Study on the effects and its mechanism of shear rate on friction of planar joints
YUAN Wei1，LI Jianchun1，2
(1. School of Civil Engineering，Southeast University，Nanjing，Jiangsu 211189，China；2. Engineering Research Center of Safety and Protection of Explosion and Impact of Ministry of Education，Southeast University，Nanjing，Jiangsu 211189，China)
Abstract：Understanding the friction behavior of planar rock joints is the basis for exploring the shear mechanical properties of undulating joints and rough joints. It is also of great significance for preventing caverns from instability and slope landslides. To explore the relationship between the friction behavior and the shear rate，firstly，artificial rock joints are subjected to direct shear tests at 5 shear rates；and then，variations in shear strength，friction coefficient，shear stiffness and joint surface abrasion with shear rate are analyzed. Finally，combined with the particle discrete element method，the effect mechanism of shear rate on friction coefficient is analyzed from the perspective of contact shift. Tested results show that with the increase of shear rate，shear strength and stiffness show a decreasing trend，and the decreasing amplitude gradually weakens. Under different normal pressures，similar increasing trends of shear strength and stiffness can be observed. The friction coefficient of a joint surface and the logarithm of shear rate are negatively correlated，and the corresponding empirical model is obtained by regression. The scratch depth of a joint surface tends to decrease with the increase of shear rate. The abrasion area may be less affected by shear rate. Simulated results show that the increased shear rates shift the position of center points of the joint contacts. Therefore，the contact overlap of particles decreases，resulting in a decrease in the contact shear force. The macroscopic manifestation is a decrease in the shear strength and the friction coefficient. The increase of shear rate leads to a decrease of abrasion depth of asperities on the joint surface，which is an important effect mechanism of shear rate on the friction behavior of joints.
袁 伟1，李建春1，2. 剪切速率对平直节理摩擦行为的影响及其机制研究[J]. 岩石力学与工程学报, 2021, 40(S2): 3241-3252.
YUAN Wei1，LI Jianchun1，2. Study on the effects and its mechanism of shear rate on friction of planar joints. , 2021, 40(S2): 3241-3252.
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2021, Vol. 40 
