常温下砂岩的变形特征及其影响因素

Deformation Characteristics of Sandstone under Normal Temperature and Affecting Factors

本文研究了常温下砂岩的变形特征。发现低围压条件下，砂岩表现为脆性剪切破裂．并产生扩容现象，而在高围压条件下，则表现为塑性流动。在塑性流动过程中，孔隙破裂，砂粒被压碎，并发生旋转和滑动，砂岩体积收缩，并表现为应变硬化。在砂岩由脆性剪切破裂向塑性流动的转化过程中，砂岩的孔隙率和围压起了关键的作用。本文还研究了砂岩孔隙破裂的机制。随着围压的增加，孔隙破裂分为两个阶段：第一阶段是孔隙边缘的剪切破裂；第二阶段表现为砂粒压碎、旋转和滑动，伴随破碎的砂粒流进破裂的孔隙空间，设想了砂粒的压碎模型。

his paper studies experimentally deformation characteristics of sandstone.It is found that brittle shearing fractures occur in sandstone at low confining pressure;while at high confining pressure,there is ductile cataclastic flow in sandstone.In the process of ductile flow,pores collapse,and sand grains are crushed,rotated and slided.The volume of sandstone shows compaction,with strain hardening.Porosity and confining pressure-play a key role in the brittle ductile transition. At last,this paper studies the mechanism of pore collapse.The process of pore collapse is divided into two stages.In the frist stage,the mechanism is the shearing fractures adjacent to the pores; in the second stage,the mechanism involves crushing,rotating and sliding on grain boundaries,with accumation of wear products in the pore spaces.