砂岩单面吸水强度软化实验

为了更附合巷道围岩吸水的实际状态,通过对两组单面吸水后的砂岩试件进行单轴抗压强度实验,研究其随吸水时间变化的强度软化特征。结果表明:两组试件单轴压缩σ-ε曲线线形相似,属于塑性-弹性-塑性变形类型,试件抗压强度随吸水时间呈负指数衰减趋于饱水强度,强度软化系数与吸水时间呈负相关性。试件宏观破坏形式主要为楔劈型张剪破坏和拉伸破坏,而且吸水一端总是首先破坏。砂岩在单面吸水状态下,强度软化机制为黏土矿物遇水膨胀机制与微观力学机制。

Softening experiment on single-side absorption strength for sandstone

Aimed at a greater conformity with the actual state of roadway surrounding rock water uptake,this paper introduces uniaxial compressive strength test of the two groups of sandstone specimens,which absorb water only on single side to obtain the softening characteristic varying with absorption time.The result shows that the two groups of speciments have the much similar σ-ε compressed curve,classified into plastical-elastical-plastical deformatoin type.The compressive strength for both specimens tend to the saturable strength with negative exponentially proportional to the absorption time,softening coefficient of compressive strength shows negative correlation to the absorption time.The mainly macroscopic crack for the specimens occur in the form of wedge-splitting and tensile failure,and the first cracking is always at absorbing side.It follows that the strength softening mechanism for the single-side absorpting sandstone could be described as absorption expansion mechanism and micromechanics mechanism.