不同温度下裂隙花岗岩法向刚度演变规律的试验研究

Experimental study on the evolutions of normal stiffness of fractured granites after different temperature treatments

本文研究了不同温度下裂隙花岗岩试样的法向刚度演变规律,并系统阐述了裂隙岩体法向闭合过程中法向位移(δn)、初始开度(b)、温度(T)及饱和状态对试样法向刚度演变规律的影响。试验结果表明,随着法向位移的增加,法向刚度的变化速率逐渐增大,呈现出二次函数关系。当法向位移相同时,初始开度较大试样法向刚度相对较小。对于不同初始开度的试样,当旋转角度(α)为20°且δ_(n)=1 mm时,饱和试样的刚度随着温度的升高(从25℃到600℃)而降低48.18%。当T=25℃且α=20°时,干燥和饱和试件刚度分别为27.31×10^(3)MPa/m和19.32×10^(3)MPa/m。提出了两个经验模型来预测干燥与饱和状态下裂隙花岗岩试样在不同温度、初始开度和法向应变等参数下的法向刚度变化规律,预测结果与实验结果吻合良好。

This study experimentally investigated the evolutions of normal stiffness of fractured granites after different temperature treatments.The influences of normal displacement(δn),initial aperture(b),temperature(T),and saturated condition on the closing behavior of specimens with different openings under normal stress are systematically investigated.The results show that the changing rate of normal stiffness increases gradually with the increment of normal displacement following a quadratic function.When the normal displacement is the same,the stiffness of the specimen with a larger initial opening is relatively smaller.For specimens with various initial openings,the stiffness of saturated specimens decreases with the increasing T(from 25℃to 600℃)by 48.18%when the rotation angle(α)is 20°and δ_(n)=1 mm.When T=25℃ and α=20°,the stiffnesses of dry and saturated specimens are 27.31 GPa/m and 19.32 GPa/m,respectively.Finally,two empirical models are proposed to evaluate the variations in stiffness of specimens which are correlated to the parameters such as T,b,and normal strain,and the predicted results are in good agreement with the experimental results.