采动裂隙岩体压剪渗透规律试验研究

An experimental study on compressive shear seepage laws of mining-induced fractured rock mass

根据采动过程中裂隙岩体的应力变化,用法向载荷、剪切载荷和渗透水压分别模拟开采过程中采场的水平应力、垂向应力和水头压力,应用JAM-600型剪切-渗流耦合试验系统对裂隙岩体进行压剪-渗流藕合试验,探讨在恒定法向荷载(CNL)和法向刚度(CNS)条件下,裂隙岩体的法向载荷、裂隙粗糙度与渗透水压对试样的位移、应力和渗流性的影响规律,分析剪切位移大小和岩体裂隙的剪胀特性对裂隙岩体的剪切应力、法向位移、节理水力开度及渗透率影响规律。研究表明:剪切应力和水头压力对裂隙水力开度起促进作用,水平地应力对水力开度变化起抑制作用。随着剪切位移变化,水力开度可分为变小或持平、增大、稳定3个阶段。裂隙表面粗糙度越大,裂隙岩体的刚度越小,则水力开度最终稳定值越大。由于裂隙岩体的剪胀作用渗透率先变小后增大,剪切位移增大,渗透率增大;法向荷载增大,试件的渗透率越小;裂隙表面越粗糙,其渗透率越大,其研究结果可为岩体透水通道形成时的孕育、萌生和爆发的导渗灾变演化过程提供理论基础。

According to the stress variation of fractured rock mass,the horizontal stress,vertical stress and water head pressure of mining stope were simulated by the normal load,shear load,and seepage water pressure during the mining process,respectively.In this study,the compression-shear seepage coupling experiment was conducted by using JAW-600 type shear seepage coupling testing system.Then the effects of normal load of fractured rock mass,roughness of joint,and seepage water pressure on the displacement,stress and permeability of specimens were discussed under the conditions of constant normal load（CNL） and constant normal stiffness（CNS）.Besides,the influence laws of the shear displacement and dilatancy properties of fractured rock mass on shear stress,normal displacement,the hydraulic opening of joint and permeability were analyzed as well.It is shown that the hydraulic opening of fractured rock mass was promoted by shear stress and water head pressure,whereas its change was inhibited by the horizontal stress.Moreover,the hydraulic opening was divided into three phases,namely smaller or unchanged phase,increasing phase,stable phase with the change of shear displacement.It is found that the greater final stable value of hydraulic opening depended on the higher roughness of joint and the lower stiffness of fractured rock mass.In addition,the permeability firstly decreased and then increased owing to the dilatancy of fractured rock mass.The permeability increased with the increase of shear displacement and the roughness of joint surface,but decreased with the increase of normal load.Therefore,this study can provide the theoretical basis for the permeable channels,initiation and outbreak of permeability disaster evolution process in fractured rock mass.