基于粘结和摩擦特性的岩石变形与破坏的研究

就微观结构而言,矿物颗粒之间或相互粘结或相互分离,Coulomb准则的粘结力和内摩擦力在局部不能同时存在.粘结力是在变形作用下丧失的,材料丧失粘结力之后通过摩擦承载.若承载能力降低,屈服破坏仅在局部断面发生,具有脆性特征;反之将发生分布的屈服破坏,具有延性特征.围压增加可以使裂隙能够承载的摩擦力超过岩石材料的粘结力,那么当轴向应力增加到粘结力时,材料发生剪切屈服产生塑性变形,而摩擦力不会增加到其最大值,裂隙也不发生滑移.利用摩擦的概念可以理解不同岩石的变形、承载和破坏随围压变化的特征. 

STUDY OF DEFORMATION AND FAILURE OF ROCK BASED ON PROPERTIES OF COHESION AND FRICTION

In terms of microscopic textures, mineral particles are either cohesive or separated, and the cohesive force and intemal frictional force of the Coulomb criterion cannot exit together locally. Cracks are produced and increase gradually with deformation, and the cohesion between particles in material loses with the deformation. The new cracks will produce friction and the shear stress of the material is supported by friction. If the loss of cohesive forces reduces the supporting capacity, then yield and failure will occur in localized fracture surfaces of a specimen and show the brittle character, otherwise the yield and failure will be distributed and show the ductile character. With increasing confining pressures, the frictional force of fissures will exceed the cohesive force of rock material. Then when the axial stress increases to the value of the cohesive force, shear yield will occur in material, producing plastic deformation. The frictional force will not increase to its maximum but keep the value of cohesive forces and the fissures will not slide either. Knowledge of the concept of friction is the key to understanding the deformation, strength and failure of various kinds of rock with changes in confining pressure.