围压变化作用下基于水力开度变化的单裂隙渗流特性研究

Based on Fracture Deformation Under Different Confining Pressures

地下水流动及相应的溶质运移受广泛且复杂分布的地应力的影响,因此对不同围压下渗流的相关研究显得尤为必要。本文以基础的本构方程为出发点,对围压作用下的渗流进行定量的分析。基于水力开度的变化和单个结构面闭合变形法则,建立考虑围压下单裂隙的渗流特性,即渗流压力(P_(s))、水力开度(e_(h))、渗透率(k)和围压(P(c))的关系模型。在岩心夹持器中进行大理岩的单裂隙渗流实验,并对试验数据进行回归分析。结果表明,该模型可有效地预测不同流量下的渗流压力、水力开度和渗透率与围压的非线性关系。在单裂隙中定流量条件下,围压与渗流压力正相关,且呈现为过量渗流压力形式的非线性关系。水力开度和渗透率在12 MPa围压内快速下降,围压大于12 MPa后呈趋于稳定的非线性关系。

It is necessary to study the seepage flow under different confining pressures in laboratory because the real groundwater flow and solute transport are affected by the extensive and complex distribution of in-situ stress.In practical projects such as groundwater pollution prevention and control,the permeability of fractures is significantly affected by confining pressure.Based on the basic constitutive law,the seepage flow under confining pressure is analyzed quantitatively in this paper.Based on the deformation of hydraulic aperture and the deformation law of fracture,the relationship model between seepage characteristics(seepage pressure P_(s),hydraulic aperture e_(h) and permeability k)and confining pressure P(c)under confining pressure is established.The hydraulic experiment of a single fracture of marble is carried out in a core holder,and the experimental data are regressed.It is verified that the model has a high fitting effect.It can effectively predict the relationship between the seepage characteristics(seepage pressure,hydraulic opening and permeability)and the surrounding pressure.