不同粗糙度和充填隙宽下石灰岩裂隙渗流特性试验研究

Experimental investigation on seepage characteristics of limestone fractures with different roughness and filling gap width

为探究不同粗糙度和充填隙宽对石灰岩粗糙单裂隙渗流特性的影响。结合三维扫描和雕刻技术,制备不同节理粗糙度系数JRC和起伏度R_(s)石灰岩裂隙面试样,开展围压和渗压作用下石灰岩粗糙单裂隙渗流特性试验,研究不同JRC和充填隙宽B_(e)对裂隙渗流量、等效水力隙宽和渗透率等渗流参数的影响。结果表明:不同JRC和B_(e)条件下裂隙渗流量、等效水力隙宽和渗透率随渗透时间的演化过程均存在快速下降、缓速下降和趋于稳定3个阶段;随裂隙面JRC增大或B_(e)减小,各渗流参数逐渐减小;稳定期裂隙渗流量和渗透率与JRC分别呈二次和对数函数关系,平方根R^(2)最小值为0.9855;稳定期渗流量与B_(e)呈二次函数关系,R^(2)最小值为0.9962,不同充填隙宽裂隙的等效水力隙宽随渗透时间增加而减小。依据初始渗流量及各参数之间的定量关系,可预测稳定后的裂隙渗流性态。

In order to investigate the influence of different roughness and filling gap width on the seepage characteristics of rough single fracture of limestone.Combined with three-dimensional scanning and engraving technologies,samples of limestone fractures with different joint roughness coefficient(JRC)and undulation(R_(s))were prepared.Seepage characteristics experiments of rough single fracture of limestone under triaxial stress condition were conducted to study the influence of different JRC and filling gap width(B_(e))on fracture seepage flow,equivalent hydraulic aperture and permeability.The results show that under different JRC and Be conditions,the evolution process of seepage flow,equivalent hydraulic aperture and permeability of fractures with seepage time has three stages:rapid decline,slow decline and stabilization.With the increase of JRC or decrease of B_(e),all seepage parameters gradually decrease.The seepage flow and permeability of fracture has quadratic function and logarithmic function relationship with JRC respectively,and the minimum value of square root(R^(2))is 0.9855.There is a quadratic function between steady seepage flow and B_(e),and the minimum value of R^(2)is 0.9745.The equivalent hydraulic gap width of the fractures with different filling gap width decreases with the increase of seepage time.According to the quantitative relationship between the initial seepage flow and various parameters,the seepage behaviour of the fracture after stabilization can be predicted.