渗流作用下柱状节理岩体强度特性试验

Experimental study on strength characteristics of columnar jointed rock mass under the seepage

为研究白鹤滩水电站柱状节理玄武岩在高渗透压力作用下的强度特性,采用与水电站现场岩体物理力学性质相近的人工材料,制作具有相同节理构造的柱状节理岩体模型试样,开展了不同渗透压力的渗流应力耦合三轴力学试验,分析了渗透压力对柱状节理岩体的破坏模式、强度和渗流量的影响。试验结果表明:渗流作用下柱状节理岩体的破坏模式为沿着节理倾角的滑移破坏;渗流作用下的柱状节理岩体具有较低的强度,三轴压缩峰值强度与渗透压力呈负相关关系;应力应变曲线可分为4个阶段,渗流量随应力应变曲线呈现出阶段性特征,渗透压力对岩体强度和渗流量影响较明显。

Columnar jointed basalt develops in the arch dam foundation and the dam abutment of Baihetan Hydropower Station.After the water storage in the hydropower station,the head difference between the upstream and the downstream of dam will form a high seepage pressure,and the strength characteristics of rock mass under high osmotic pressure is one of concerned scientific issues in rock engineering.Therefore,artificial material with physical and mechanical characteristics similar to those of in-situ rock mass was used to make the columnar jointed rock mass model samples with the same joint structure.In order to investigate the effect of seepage flow pressure on the failure modes,strength and seepage quantity of jointed rock mass,a series of triaxial tests on the columnar jointed rock mass samples were carried out under different osmotic pressures.The experimental results indicate that the failure mode of columnar jointed rock mass is sliding failure which alongs the joint dip angle under seepage flow pressure.Moreover,the columnar jointed rock mass has a lower strength under seepage,and the peak strength of triaxial compression test is negatively correlated with the osmotic pressure.Furthermore,four stages for the stressstrain curve of columnar jointed rock mass under triaxial compression condition are summarized based on test results,and seepage quantity shows phased characteristics with the stress-strain curve.Additionally,the effect of seepage on columnar jointed rock mass strength and seepage flow is obvious.