黄岛地下水封洞库地应力对裂隙岩体渗透特性影响研究

Effect of Geostress on the Permeability of a Fractured Rock Mass in the Huangdao Underground Water-Sealed Storage Cavern

裂隙岩体渗透特性是评价地下水封洞库水幕系统水封效果的核心内容,而裂隙岩体总是赋存于一定的应力场和渗流场中,因此,研究地下水封洞库地应力对裂隙岩体渗透特性的影响具有重要意义。文章以黄岛地下水封洞库建库围岩为例,首先介绍了裂隙岩体渗流运动的基本规律及应力对渗流作用的影响机理;在此基础上,通过水压致裂法和压水试验分别得到了研究区岩体地应力、渗透特性参数及其随孔深的分布规律,并通过回归分析建立了裂隙岩体渗透系数与地应力关系表达式。结果表明,渗透系数随地应力增大而逐渐减小,并呈负指数变化规律。最后分析了渗透系数与地应力呈负指数关系的主要原因。该研究结果可为地下水封洞库埋深设计、水幕孔布置等提供参考。

The permeability of a fractured rock mass is a key parameter for evaluating the water-sealing effect of water curtain systems in underground water-sealed storage caverns. As fractured rock masses always exists under the conditions of stress and seepage fields, it is important to study the effects of the geostress of underground water-sealed storage caverns on the permeability of fractured rock masses. Using the Huangdao underground water-sealed storage cavern as an example, this paper presents the basic law of seepage flow in a fractured rock mass and the influence mechanism of stress on the seepage effect. The geostress and permeability parameters of a rock mass in the studied area and their distribution rules with an increase of hole depth are obtained by hydraulic fracturing and pump-in tests, and a relational expression of the geostress and permeability coefficient is established by a regression analysis. The results show that the permeability coefficient decreases with an increase of geostress and presents a negative exponential law. Consequently, the main causes for the negative exponent relationship between the permeability coefficient and geostress are analyzed.