为研究不同化学溶液对砂岩力学性质及能量特征的影响,采用不同的水化学溶液对砂岩试样进行腐蚀,利用WDT-1500多功能材料试验机对化学腐蚀后饱和状态与自然状态的试样进行常规三轴压缩试验。试验结果表明:化学腐蚀后砂岩试样的强度及其抗变形能力呈现不同程度的劣化;化学腐蚀后砂岩试样的峰值应变小于相同围压下自然状态试样的峰值应变,与单轴压缩条件下不同,这可能是由于围压和化学溶液共同作用的结果;砂岩试样的似软化系数与围压之间呈现负相关性,同时,其降低速率随着围压的增加而降低。砂岩试样峰值前吸收的能量绝大部分是以可释放弹性应变能Ue形式储存下来的,而化学腐蚀后砂岩试样以Ue形式储存下来的能量占其总吸收应变能的百分比却有所下降;同时,围压与试样的可释放应变能/应变能比值之间呈负相关性,而与耗散能/应变能比值存在正相关性;岩石脆性指标修正值呈现不同程度的增加,试样的脆性减弱延性增强,即塑性变形增加,塑性变形与耗散能之间具有很好的线性特征。溶液的pH值、浓度和化学成分对砂岩试样峰值处各部分应变能的影响显著。
In order to study the influence of different chemical solution on mechanical properties and energy mechanism of sandstone,the sandstone samples were corroded by different water chemical solutions first.Conventional tri-axial compression experiment was carried out for samples subjected chemical erosion and in saturated state and samples in natural state respectively by using WDT-1500multi-functional material testing machine.Experimental results show that the strength and antideformation ability of sandstone exhibit different deterioration degrees after chemical erosion.The peak strain of sandstone specimens subjected to chemical corrosion is less than that in natural state and under the same confining pressure,which is different from uni-axial compression.This could be the result of a combined effect of confining pressure and chemical solution.There is a negative correlation between the similar softening coefficient and confining pressure of sandstone specimens,at the same time,its reduction rate decreases along with the confining pressure increase.Most pre-peak absorbed energy of sandstone specimens is stored in the form of the elastic strain energy Ue,but after chemical erosion,for total absorbed strain energy,the percentage of that part of energy stored in sandstone specimen in the form of Ue decreases;there is a negative correlation between confining pressure and the elastic strain energy/strain energy,but a positive correlation between confining pressure and the dissipation energy/strain energy.Revised rock brittleness index values increase at different degrees,the brittleness of specimens decreases and its ductility enhances,namely the plastic deformation increases.Plastic deformation of sandstone specimens has a good linear relationship with dissipation energy.The effect of pH value,concentration and chemical composition of solution on strain energy at corresponding peak stress positions is significant.