热力耦合作用下硬脆性岩石蠕变性质试验研究

Experimental Study of Creep Properties on Hard Brittle Rock under Thermal-Mechanical Coupling

以齐热哈塔尔水电站引水隧洞高温段的片麻状花岗岩为例,通过不同温度下的室内分级加载三轴蠕变试验,获得了热力耦合作用下岩石稳态蠕变率和强度的变化规律,揭示了考虑温度影响的蠕变破坏模式。结果表明,片麻状花岗岩稳态蠕变率与温度呈非线性正相关,经典软岩稳态蠕变率模型对片麻状花岗岩同样适用;岩石的长期强度与温度呈负相关,并获得了硬脆性岩石长期强度随温度和围压变化的三元素实用公式;随着温度升高,岩石破坏模式呈现由单斜面剪切破坏到共轭剪切破坏的转变,高温对硬岩具有显著软化作用。

Taking the gneissic granite of high temperature section in the diversion tunnel of a hydropower station as the research object,through the laboratory step-loading triaxial creep test under different temperatures,the change law of steady-state creep rate and strength of rock under the thermal-mechanical coupling is obtained,and the creep fracture mode is revealed considering the influences of temperature.Research results show that steady-state creep rate of gneissic granite is nonlinear positive relation with the temperature,and the classical steady-state creep rate model of soft rock is also applicable to the gneissic granite;The long-term strength of rock is negatively correlated with temperature,the three element practical formula for the long-term strength variation of hard brittle rock with temperature and confining pressure is obtained;With the increase of temperature,the fracture mode of rock shows the transition from single plane shear failure to conjugate shear failure.What's more,high temperature has a significant softening effect on hard rocks.