化学溶蚀及高温作用下砂岩力学特性的试验研究

Experimental Research on Mechanical Properties of Sandstone After Chemical Corrosion and High Temperature Exposure

为探究化学溶蚀及高温作用对砂岩力学性能的影响,将砂岩分别在水、HCl和NaOH溶液中浸泡后,经高温处理,再进行单轴压缩试验和三点弯曲试验,并借助扫描电子显微镜和X射线衍射仪分析其损伤机理。试验结果表明:高温使NaOH溶液浸泡后的砂岩单轴抗压强度得到明显提高,而在温度低于400℃时,HCl溶液和水浸泡后的砂岩单轴抗压强度随着温度的升高呈劣化趋势;NaOH溶液使砂岩的断裂韧度降低了16.05%,断裂韧度和抗拉强度随温度的升高总体呈下降趋势,400℃是断裂韧度及抗拉强度发生劣化的门槛温度。高温和化学溶蚀的共同作用改变了砂岩的矿物成分、结晶度及结构完整度,使砂岩的力学性能受到影响。

To clarify the effects of chemical corrosion and high temperature on mechanical properties of sandstone,the uniaxial compression and three-point bending tests were carried out on sandstone samples that were immersed respectively in water,HCl,NaOH solutions and then suffered to high temperature treatment.The damage mechanism was analyzed by the patterns from scanning electron microscope and X-ray diffraction.The experimental results show that the uniaxial compressive strength of sandstone after immersed in NaOH solution and high temperature treatments is obviously improved,but deteriorates gradually when the temperature is below 400 ℃ for that immersed in HCl solution and water.The fracture toughness of sandstone after immersed in NaOH solution decreases by 16.05%.As the temperature increases,the fracture toughness and tensile strength decrease generally.As a result,400 ℃ is the threshold temperature of deterioration of fracture toughness and tensile strength.The internal mineral composition,crystallinity and structural integrity of sandstone are changed after chemical corrosion and high temperature treatment,which affects the mechanical properties of sandstone.