透明类岩石内蕴裂纹扩展变形试验研究

Experimental Studies on Crack Propagation and Coalescence in Transparent Rock

采用力学试验手段探究岩石受压情况下内部裂纹扩展贯通机理是了解岩石破坏失稳机制的重要手段。由于真实岩体内部裂纹无法直接观察其扩展过程,通过自行研制的透明类岩石材料在RMT-150B多功能全自动刚性岩石伺服试验机上进行单轴压缩力学试验,观察研究透明类岩石内部三维裂纹的扩展贯通机理。这一方法克服了真实岩体不透明的特点,更方便地观察岩体内部裂纹萌生扩展不同阶段的形状。通过对透明岩石内部布置不同长度和角度的裂隙,模拟不同长度和角度的原生节理裂隙对岩体破坏失稳的影响。研究结果表明:含预制裂纹的透明类岩石试件在压缩过程中三维裂纹的起裂扩展要比二维条件下复杂,大致经历了压密,弹性变形,裂纹扩展,脆性破坏四个阶段。含预制裂隙的试件其峰值强度和峰值轴向应变比完整试件均有明显降低,且预制裂隙的长度对峰值强度和峰值轴向应变的降低幅度有一定影响。试验成果无疑对分析真实岩体的破坏失稳机理有着重要的参考价值。

Investigating the mechanism of 3 d crack propagation and coalescence in rock under compression by mechanics experiment is an important means to understand the damage mechanism of instability of rock mass.Because of the real rock with internal cracks cannot be directly observed,the uniaxial compression tests on transparent rock-like material which is developed by myself are done on the RMT-150B multi-function automatic rigid rock servo material testing machine to observe and study the mechanism of 3d cracks propagation and coalescence process which are in the transparent rock-like material.The method overcome the character of real rock is not transparent and is convenient to observe the internal crack initiation of rock mass.Through setting the different angles and lengths of pre-existing crack to simulate influence on the instability of rock mass damage in different angle and length of the original joints.The results showed that 3d crack propagation and coalescence process is much more complex than that of 2d crack,the failure process of the simple can be divided into four stages which are compression,elastic deformation,crack propagation and brittle failurg.Compared with the intact sample,the peak strength and peak axial strain of the sample with pre-existing are all lower,and the reduction extent is closely related to the length of the pre-existing crack.The research result offers great reference value to analysis the mechanism of rock damage and instability.