温度-应力耦合作用下砂岩破坏特性试验研究

Experimental Study of Failure Characteristics of Sandstone under Coupling of Temperature and Stress

为探究一般工程温度条件下砂岩变形破坏过程及力学特征,以三峡库区白水河滑坡库岸段砂岩为研究对象,采用TOP INDUSTRIE岩石三轴试验仪,分别在不同温度(0°、20°、40°、60°)、不同围压(5MPa、10MPa、15MPa、20MPa)耦合作用下进行常规三轴压缩试验研究.结果表明:砂岩试样在不同温压作用下应力-应变关系曲线形态和趋势极为相似,变形破坏形式没有明显变化,均在达到峰值强度后快速破坏,并且以剪切破坏为主,在常温下的破坏面形态单一,随温度的升高破坏过程会更复杂;砂岩试样的弹性模量和峰值应变均伴随着围压的增大而增大,随着温度的升高而降低;粘聚力及内摩擦角随温度的升高均呈下降趋势,粘聚力的下降幅度远大于内摩擦角的降幅;温度、应力作用下的砂岩耦合效应对岩体变形破坏有重大影响,考虑砂岩温度-应力耦合作用的稳定性评价对工程设计具有重要指导意义.

To explore the deformation failure process and mechanical characteristics of sandstone under gener- al engineering temperature conditions, the sandstone of Baishuihe landslide in the Three Gorges Reservoir ar- ea is regarded as the research object and the TOP INDUSTRIE rock triaxial test instrument is used to carry out the conventional triaxial compression test at different temperatures of 0 ℃, 20℃, 40℃, and 60℃ and dif- ferent confining pressures of 5 MPa, 10 MPa, 15 MPa and 20 MPa. The results show that the patterns and trends of the stress-strain curves of sandstone samples are very similar in different temperatures and pres- sures; the deformation failure mode doesn＇t change significantly and both in rapid damage after peak strength; meanwhile, most of them are shear failure. The shape of the failure surface is single under normal tempera- ture~ and the failure process will be more complicated with increasing of temperature. The elastic modulus and peak strain of sandstone increase with the rise of confining pressure, and decrease with the rise of temper-ature. The cohesion and the internal friction angle increase as the temperature decreases; and the decrease of cohesion is much larger than that of internal friction angle decrease. The coupling effect of sandstone under the influence of temperature and stress has a significant impact on rock deformation and failure; so it is of guiding significance to consider the stability evaluation of sandstone under the coupling of temperature and stress in the engineering design.