化学腐蚀和高温作用后白砂岩物理损伤及力学性能的试验研究

Experiment on physical deterioration and mechanical property of white sandstone under role of chemical corrosion and heating

研究了化学腐蚀及高温作用对福建宁德白砂岩的物理、力学性能的影响。白砂岩试件在HNO3溶液中浸泡90 d后取出进行高温加热,加热温度分别为200、400、600及800℃。对试件进行物理参数及单、三轴压缩作用下力学性能的测定,分析化学腐蚀及高温作用对白砂岩应力-应变曲线、峰值应力、弹性模量等的影响。研究表明:化学腐蚀及高温作用对白砂岩物理、力学性能的影响并不相同。HNO3溶液浸泡及高温引起白砂岩内部结构损伤,增大了孔隙率,导致弹性模量减小。另一方面,化学损伤及高温加热对白砂岩试件的四阶段应力-应变曲线形态也有影响,峰值应力损失率随温度升高而升高。此外,与单轴压缩相比,三轴压缩过程中的围压对于岩石的受力性能有利,对于单轴压缩,酸浸泡及高温作用在损伤岩石物理性质的同时也对其力学特性有不利影响,峰值应力损失率与弹性模量损失率基本成线性关系;对于三轴压缩,只有当弹性模量损失率大于14%时,岩石的峰值应力才受损,反之,峰值应力不降反升。

The effect of chemical corrosion and high temperature on the physical and mechanical properties of Ningde white sandstone in Fujian Province was investigated. The specimens were firstly immersed into HNO3 solution and kept for 90 days, and then were heated up to different temperatures ranging at 200,400,600 and 800℃. The paper examined physical parameter and mechanical properties under uni- and tri-axial compression and analyzed the influence of chemical corrosion and high temperature on stressstrain curve, peak stress and elastic modulus. Results show that the effect of chemical corrosion and high temperature on the physical and mechanical properties of white sandstone is not the same. Tthe HNO3 immersion and heating deteriorated the internal structure of white stone specimens, increased porosity and resulted in the decrease of elasticity modulus. On the other hand, the shape of the stress-strain curves in four stages also changes due to the chemical corrosion and thermal effect, and the peak stress loss increases as the temperature increases. Furthermore, the confining pressure in tri-axial compression is beneficial to the mechanical properties of white sandstone compared to uni-axial compression. For uni-axial compression, both the physical and mechanical properties are deteriorated due to the chemical corrosion and high temperature in the way that the peak stress loss is in a linear relationship with elastic modulus loss. For triaxial compression, only when the loss rate of elastic modulus is larger than 14%, the peak stress of white sandstone is damaged. Otherwise the peak stress increases instead of decreasing.