腐蚀环境板岩贯通裂隙渗透特性变化规律

Change law study on cut-through fracture seepage properties of slate in corrosion environment

针对板岩裂隙渗流特性受水化学腐蚀影响规律尚不明确的现状,以大连地区的板岩为研究对象,开展了板岩贯通裂隙受水化学溶液(NaCl,HCl,NaOH)腐蚀的渗透特性试验研究。首先通过对浸泡贯通裂隙试件的SEM扫描和浸泡溶液PH值对比,分析了水-岩作用对裂隙板岩微细观结构的影响机制。其次通过不同溶液、不同浸泡时间裂隙试件的渗透性试验,宏观上获得了腐蚀环境下裂隙板岩的渗透性变化规律。再次基于一系列化学反应方程式,将上述宏细观结果进行对比分析,认为裂隙板岩渗透性受水化学腐蚀影响明显,HCl,Na Cl溶液对结构面具有溶蚀作用,增大了其均值隙宽;而NaOH溶液与板岩矿物成分反应生成的稳定沉淀物质,附着、堵塞于裂隙间,使得均值隙宽减小。最后,基于试验数据建立不同溶液板岩渗透系数与浸泡时间的非线性关系,并引入裂隙渗流计算理论公式,采用FLAC^(3D)的fish语言编写板岩裂隙化学-渗流-应力耦合计算程序,计算与试验结果具有较好的一致性。

As the law of slate fissure seepage characteristics affected by chemical corrosion is unclear,a seepage characteristic experiment of slate cut-through fracture in hydrochemical solutions（ NaCl,HCl,NaOH） environment in Dalian area was conducted in this study. By comparing the SEM scanning and solution＇s pH,the microscopic structure mechanism of fissured slate influenced by water-rock interaction was first analyzed,and the changing law of permeability coefficient under different steeping times was obtained macroscopically. And then,the test results were contrastively analyzed based on a series of chemical reaction equations. Test results show that： hydrochemical corrosion has a significant effect on the permeability of fissured slate. HCl and NaCl solutions play an important role in corroding structural plane,and have the average gap width increased; however,the stable precipitation materials resulted from NaOH solution-slate reaction and adhered between slates gaps have the average gap width decreased. With establishing the nonlinear relationship of permeability coefficient under different solutions and steeping time,and introducing the relevanttheoretical formulas to compile the seepage-chemical-stress coupled calculation program of FLAC^3D fish language,the experiment was numerically simulated. There is a good agreement between the calculation result and the experiment result.