软弱岩脉岩体力学特性空隙水压力效应试验

以某大型水电工程坝址煌斑岩脉软弱岩体为例,将采自现场的煌斑岩完整岩块制备成已含有结构面的岩体试件,利用MTS815Flex Test GT岩石力学试验系统,采用特殊的技术手段,对其进行了系列水岩耦合三轴试验研究。针对空隙水压力对煌斑岩体强度特性与变形特性的影响,以及围压对变形特性的影响进行了相关性分析,建立了相应的预测模型。结果表明岩体内聚力c与空隙水压力有密切的关系,随空隙水压力增大而迅速降低,甚至完全丧失;内摩擦角φ在空隙水压力作用下变化很小。整体上看,围压增加增大了变形模量与泊松比,而空隙水压力增加则减小了变形模量,增大了泊松比。

Experimental Study on Mechanical Properties of Weak Rock Mass Obtained from Dyke under Interstitial-Hydraulic Pressure

Taking the dike in the weak rock mass from the dam foundation of a large scale hydropower project for example,and using the MTS815 Flex Test GT rock mechanics test system and some special technical means,the rock mass specimens with structural planes had been produced from the intact rock of lamprophyre obtained from the working site.A series of triaxial compression tests of water-rock coupling under the confining pressure and interstitial-hydraulic pressure had been conducted on the lamprophyre specimens.The effects of the interstitial-hydraulic pressure on the strength and deformation of the rock mass specimens and the effects of the confining pressure on the deformation of the rock mass specimens were analyzed and the corresponding prediction models had been built.The results showed that the cohesion of rock mass had a close relationship with the interstitial-hydraulic pressure and it decreased rapidly with the increasing of the interstitial-hydraulic pressure and can even disappear.The internal friction angle changed a little with the interstitial-hydraulic pressure.Overall,the deformation modulus and Poisson ratio increased with the increasing of the confining pressure;whereas the deformation modulus decreased and the Poisson ratio increased with the increasing of the interstitial-hydraulic pressure.