渗流-应力-化学耦合作用下岩石裂隙渗透特性试验研究

EXPERIMENTAL STUDY OF SEEPAGE PROPERTIES IN ROCKS FRACTURE UNDER COUPLED HYDRO-MECHANOCHEMICAL PROCESS

为研究渗流-应力-化学耦合作用下岩石裂隙渗透特性变化规律,设计3组试验工况,在改变渗透压以及化学溶液的条件下,分别测定每种工况下的渗出水流量、渗出水离子浓度值以及渗出水pH值变化情况,进而得出裂隙渗透特性变化情况。通过处理试验数据,总结分析各因素对裂隙渗透特性的影响,并建立裂隙开度变化率与渗出水中钙离子浓度值之间的关系式。试验结果表明,渗出水流量、裂隙开度总体趋势是随着时间逐渐减小的,最终趋于稳定状态;增大渗透压,稳定状态会被打破,裂隙的流量和开度都会增大,但最终趋于另一个稳定状态;化学溶液对岩体裂隙的侵蚀性大,对岩体渗透性的影响更明显。通过分析和提炼渗出水流量、裂隙开度、渗出水的离子浓度值以及渗出水的pH值等随时间变化的数据,及它们之间的内部关系,在理论上描述岩体裂隙在渗流-应力-化学耦合作用下的渗透特性,进一步揭示渗流-应力-化学耦合作用机制。

In order to research the hydro-mechano-chemical process in fractured rock, we designed three different kinds of experimental conditions, changing the osmotic pressure and the chemical solution for injection. During these three tests, we measured the seepage discharge, ion concentration and the pH value for observing the seepage properties in fractured rock. Through analyzing the test data and the summary about the characteristics of fractured rocks under different factors, a kind of relationship between the aperture variance ratio and the ion concentration of seepage was established. The test results indicate that： the seepage discharge and the fracture opening all decrease with time, and reach stable state eventually; the improvement of seepage pressure results in the increase of discharge through fractured rocks, correspondingly, the aperture enlarged which the permeability properties of those fractured rocks increased; carbonated with acidic coming through limestone can produce chemical reaction to accelerate the erosion and dissolution of the limestone, resulting in the increase of the aperture. Through analyzing the relationship among the seepage discharge, ion concentration and the pH value with time, we described the evolution of pressure dissolution, free-face solution, chemical dissolution, furthermore revealing the seepage properties of the rock fracture under coupled hydro-mechano-chemical process.