不同应变率下两种岩石的压缩破碎特征试验研究

Experimental Study on Compression and Fracture Characteristics of Two Kinds of Rocks under Different Strain Rates

为了研究不同岩石在不同应变率下压缩时裂纹的产生规律及破坏模式,将石灰岩和红砂岩制成试件,研究其在不同应变率和受力模式下裂纹的形成模式。开展了两种岩石的准静态压缩和动态压缩试验,采用高速摄影机记录了裂纹的产生和破坏模式。对两种岩石试件的裂纹形态进行对比,基于岩石的物理性质、受力状态、能量演化分析,得到了在不同应变率下压缩时产生差异性的原因。结果表明:准静态压缩下岩石试件受压的破坏模式也会因应变率的不同而存在差异,并且破坏模式的差异对岩石试件的抗压强度将产生显著的影响;从能量演化的角度分析,入射能量的大小将会决定岩石试样动态抗压强度曲线是否出现起伏;动态压缩时,裂纹的周向扩展速度与岩石抗压强度呈正相关。

To better understand crack generation laws and failure modes of various rocks compressed under different strain rates,specimens made from limestone and red sandstone were respectively prepared and their crack formation under different strain rates and stress modes was investigated in both quasi-static and dynamic compression tests.High-speed photography was used to record cracks occurrence as well as failure modes.By analyzing the rocks’physical properties,stress state,and energy evolution in comparison,reasons for the crack morphology variation in compression under different strain rates were obtained.It is shown that:(1)the failure modes of rock specimens under compression in the quasi-static range vary with strain rates,and the compressive strength of rock specimens are significantly effected by different failure modes;(2)the magnitude of incident energy determines the fluctuation of the dynamic compressive strength curve of the rock sample;(3)under dynamic compression,the circumferential growth rate of crack is positively correlated with the compressive strength of rock.