冻融循环作用下中部锁固岩桥破坏试验研究

Experimental study on failure of central rock bridge under freeze-thaw cycle

为探究高寒地区中部锁固型边坡的变形破坏机制,对3种不同岩桥角度岩样开展冻胀力监测试验及不同冻融循环次数下的单轴压缩试验。通过试验研究揭示冻融循环过程中岩样裂隙冻胀力的演化过程分为6个阶段:前期衍生阶段、陡升阶段、跌落阶段、平稳阶段、融化阶段和消散阶段。得出不同岩桥角度和不同冻融次数对岩样强度变形特征、损伤特征及破坏模式的影响规律:随着冻融次数增加,岩样峰值应力损失率呈幂函数增长,峰值应变呈二次多项式增长,相对弹性模量呈指数函数减小。损伤变量随着冻融次数增加呈幂函数增长,15°倾角岩样损伤变量最大,30°岩样损伤变量最小。岩桥角度越大,冻融次数越多,岩样越易发生岩桥贯通破坏。试验结果对于揭示寒区中部锁固型边坡冻融损伤机制具有重要意义,对寒区岩土工程建设具有参考价值。

In order to explore the deformation and failure mechanisms of central locked slopes,the frost heave force monitoring tests and uniaxial compression tests under different freeze-thaw cycles were carried out on rock samples with three different rock bridge angles.The test results reveal that the evolution process of the frost heave force in rock samples during the freeze-thaw cycle includes six stages including early derivation,steep rise,falling,stationary,melting and dissipation.The effects of the bridge angle and the freeze-thaw cycle number on strength and deformation characteristics,damage characteristics and failure modes of rock samples were discussed.It is shown that,with increasing the number of freeze-thaw cycles,the peak stress loss rate and the peak strain of rock samples respectively increase as a power function and a quadratic polynomial,while the relative elastic modulus decreases exponentially.With increasing the number of freeze-thaw cycles,the damage variable increases as a power function.The damage variable of rock samples with a crack at an angle of 15°to the vertical direction is the largest,while the damage variable with a 30°crack is the smallest.The larger the rock bridge angle or the greater the number of freeze-thaw cycles is,the more easily the bridge in the middle of the sample connects.The test results are of great significance to reveal the freeze-thaw damage mechanisms of the central locked slope and have reference value for the construction of rock engineering in cold regions.