不同粗糙度和渗透溶液下石灰岩粗糙裂隙渗流特性试验研究

Experimental study on seepage characteristics of limestone rough fracture under different roughness and seepage solutions

为探究节理粗糙度系数JRC、渗透溶液和围压加载等因素对石灰岩粗糙裂隙渗流特性的影响,选取蒸馏水和硫酸钠溶液为渗透溶液,开展不同工况下石灰岩裂隙渗透试验,结合试验前后裂隙面形貌特征,揭示不同粗糙度和渗透溶液下石灰岩粗糙裂隙渗流特性演化机制。结果表明:各工况下裂隙渗流量、等效水力隙宽和渗透率随渗透时间增加均呈现快速下降、缓慢下降和基本稳定的变化趋势,相同渗透溶液和应力条件下,裂隙面JRC越大,渗透率越小,随着围压增大,裂隙渗流量和渗透率不断减小;相较于蒸馏水,硫酸钠溶液侵蚀下的试样裂隙面变得更为粗糙,各裂隙面JRC增大3.31%~36.61%,表面粗糙参数R_(s)增大0.10%~1.05%。研究成果可为裂隙岩体裂隙渗透率和渗漏量估算提供理论支撑。

In order to explore the influences of joint roughness coefficient JRC,seepage solution and confining pressure loading on the seepage characteristics of limestone rough fractures,the distilled water and sodium sulfate solution were selected as seepage solutions to carry out limestone fissure seepage tests under different conditions.The evolution mechanism of seepage characteristics of limestone rough fracture under different roughness and seepage solutions was revealed by combining the morphological characteristics of the fracture surface before and after the tests.The results show that the fracture seepage flow rate,equivalent hydraulic gap width and permeability show a trend of rapid decline,slow decline and basically stable change with the increase of seepage time.Under the same seepage solution and stress condition,the larger the JRC of fracture surface is,the smaller the permeability is.With the increase of confining pressure,the fracture seepage flow and permeability decrease continuously.Compared with distilled water,the fracture surface of the sample corroded by sodium sulfate solution becomes coarser,JRC of each fracture surface increases by 3.31%-36.61%,and surface roughness parameter R_(s)increases by 0.10%-1.05%.The research results can provide theoretical support for the estimation of fracture permeability and leakage of fractured rock mass.