考虑卸荷作用的裂隙岩体渗流应力耦合研究

Study of hydro-mechanical coupling of fractured rock masses considering unloading effect

大量试验证明,裂隙岩体在加载和卸荷的条件下其渗流与应力特性是不完全相同的。近年来,加载条件下的裂隙岩体渗流应力耦合研究得到了长足的发展,但卸荷作用下的水岩耦合分析还处于初始阶段。基于现有裂隙变形曲线的研究结果,建立了渗透系数与卸荷应力、应变间的本构关系,在此基础上,根据算例分析了各种工况下的渗流和应力特征,其计算结果表明,考虑卸荷后应力场的改变增加了临近坡面的岩体渗透系数,降低了地下水浸润线,增加了边坡的稳定性;考虑渗流后,边坡的位移场和应力场有较大改变,但考虑耦合后位移和应力分布和大小与不耦合时的相差不大;边坡开挖后应力场改变对渗流的影响远大于渗流对位移、应力等的影响。

A large number of experiments have proved that fluid flow and stress characteristics are different from each other under loading and unloading effect state. In recent years,research on hydro-mechanical coupling of fractured rock mass under loading conditions has advanced greatly,but corresponding research on hydro-mechanical coupling considering unloading effect has still been in an early stage. And then,constitutive relationship including seepage parameters between unloading stress and strain is constructed based on existing fracture deformation curve,meanwhile,fluid flow and stress characteristic of an example under different operation modes is analyzed according to coupling theory mentioned above. The calculation results illuminated as follows:stress field changing make fluid flow coefficient close to slope surface increasing and saturated line falling so as to augment slope stability when taking consideration of unloading effect;and displacement and stress field vary greatly after considering seepage effect,but discrepancy of both characteristic distribution between considering coupling and discarding coupling was knee-high to a duck;and the final conclusion is that stress field changing influencing fluid flow field is larger than that fluid flow changing influencing displacement and stress field.