长期浸泡下白云岩抗拉强度劣化规律试验研究

Experimental Study on Deterioration Law of Tensile Strength of Dolomite Under Long Term Immersion

为研究长期浸泡水-岩作用对岩石抗拉强度的影响,特选取乌东德峡谷河段入口处右岸三台危岩体的白云岩为研究对象,对其进行碱性溶液浸泡下的水-岩作用试验.将浸泡结束后的岩样进行巴西劈裂试验、核磁共振试验、SEM电镜扫描和离子质量浓度分析,结合孔隙度变化规律和微细观结构分析抗拉力学性能劣化原因.结果表明:在水-岩作用过程中,白云岩的抗拉强度劣化趋势较满足指数分布,先快速降低后趋于稳定;孔隙度与白云岩抗拉强度基本为线性相关,抗拉强度主要受大孔隙的影响;白云岩孔隙度发生明显变化的原因主要是水-岩作用使白云岩内部的胶结物和可溶性矿物溶解.研究结果可为危岩体在库水作用下的长期稳定提供计算参数.

To study the effect of long-term immersion of water-rock interaction on the tensile strength of rocks,the dolomite samples of three dangerous rock masses on the right bank at the entrance of the Wudongde Gorge section were selected as the research object,and the water-rock interaction test under alkaline solution immersion was carried out.After the test,the rock samples were subjected to Brazilian splitting test,nuclear magnetic resonance test,SEM electron microscopy scanning,and ion concentration analysis.The causes of deterioration of tensile mechanical properties were analyzed by combining the porosity change law and microscopic structure.The results show that the deterioration trend of tensile strength of dolomite in the process of water-rock interaction is closer to an exponential distribution,which decreases rapidly at first then tends to be stable.Porosity is basically linearly related to the tensile strength of dolomite,and the tensile strength is mainly affected by micro pores.The obvious change in the porosity of dolomite is mainly due to the dissolution of cementitious materials and soluble minerals inside dolomite by water-rock interaction.The research results can provide calculation parameters for the long-term stability of dangerous rock mass under the action of reservoir water.