高温作用对花岗岩强度及变形特性的影响

Influence of high temperature on strength and deformation of granite

为考察温度对岩石强度及变形特性的影响，在实时高温（25—850℃）和高温热处理后（25—1200℃）两种情况下对花岗岩岩样进行单轴压缩试验。结果表明：①实时高温作用下，花岗岩温度应变、热膨胀系数与温度之间均有着良好的一阶增长型指数函数关系；高温作用冷却后，岩样温度应变随温度变化具有突变性。不能真实反映实时高温下岩样的变形规律。②实时高温作用下，花岗岩力学参数快速连续劣化，岩样的抗压强度从25℃时的191．90MPa降低至850℃时的55．63MPa，降幅为71．11％；弹性模量从25℃时的38．37GPa降低至850℃时的5．09GPa，降幅为86．73％，岩样的抗压强度、弹性模量随温度升高呈二阶指数规律衰减；高温作用冷却后，花岗岩力学行为呈突变状态，与结构中相变密切相关，900℃时抗压强度降为89．95MPa，比25℃下降了53．13％，弹性模量为11．02GPa，比25℃下降了71．28％。岩样的抗压强度、弹性模量随温度升高呈多项式曲线拟合关系。实验结果一定程度上反映了花岗岩在实时高温作用和高温作用冷却后其内部结构变化的基本规律，对高温岩体工程有一定的参考价值。

Experiments on granite under uniaxial compression at a high temperature of 25 to 850 % or after a thermal treatment of 25 to 1 200 ℃ were conducted to study the effect of temperature on rock strength and deformation. The results show that regression curves between temperature strain, thermal expansion coefficient, and temperature can be closely described by the first order growth ex- ponential function at the high temperature; temperature strain of rock sample has mutagenicity with the temperature after the thermal treatment of high temperature, which can not exactly reflect rock deformation at high temperature mechanical properties of granite are weakened continuously at high temperature, with compressive strength of 191.90 MPa at 25 ℃ and 55.63 MPa at 850 ℃ ,decreased by 71.11% ; elastic modulus is 38.37 GPa at 25 ℃ and 5.09 GPa at 850 ℃, decreased by86. 73% ; the relationship between compressive strength and elastic modulus has the second order at- tenuation trend of exponential function; the mechanical properties show mutation after the thermal treatment of high temperature, with compressive strength of 89. 95 MPa at 900 ℃, decreased by 53. 13% 71.28% with that compared at 25 ℃; elastic modulus compared with that at 25 ℃ ; regression curves is 11.02 GPa at 900 ℃, decreased by between compressive strength and elastic modulus and temperature can be closely described by polynomials. These resuhs reflect the funda- mental regulation that the interior structure of granite changes under the action of different tempera- ture, providing reference to rock engineering at high temperature hereafter.