冻融循环作用下岩桥变形破裂及能量转化特征研究*

为研究寒区锁固型岩质边坡的破坏机制，对岩桥试件开展冻融循环试验和单轴压缩试验。以数字图像相关方法为观测手段获得加载过程中的全局应变场，分析冻融循环作用对岩桥变形破裂演化特征的影响。引入能量特征指标，探究冻融岩桥加载过程中的能量耗散和释放规律。研究结果表明:随着冻融循环次数的增加，试件抗压强度和弹性模量逐渐劣化；冻融循环作用未改变最终破坏模式，均表现为剪切裂纹贯穿中部岩桥造成的失稳破坏。冻融循环作用促进应变集中带的出现和扩展，加剧裂隙周边的应变集中程度。随着冻融循环次数的增加，试件储能极限和应变能峰后转化率逐渐降低，说明冻融循环作用减缓能量耗散和释放；试件最终破坏与能量转化密切相关，储能极限和应变能峰后转化率越大，试件脆性破坏越显著。

Investigation on deformation fracturing and energy conversion characteristics of rock bridge under freeze-thaw cycles

To investigate the failure mechanism of the locked rock slope in cold region,the freeze-thaw cycles tests and uniaxial compression tests were conducted on the rock bridge specimens.The digital image correlation (DIC) method was applied as observation method to obtain the global strain fields during loading,and the influence of freeze-thaw cycles on the deformation and fracturing evolution characteristics of the rock bridge was analyzed.The energy characteristic parameters were introduced to study the energy dissipation and release laws of the freeze-thaw rock bridge during loading.The results showed that with the increase in the number of freeze-thaw cycles,the compressive strength and elastic modulus of the specimens deteriorated gradually.The freeze-thaw cycles did not change the final failure mode,which all represented as the instability failure caused by shear cracks penetrating the middle rock bridge.The freeze-thaw cycles promoted the initiation and propagation of strain concentration zones,and intensified the strain concentration degree around the cracks.With the increase in the number of freeze-thaw cycles,the energy storage limit and the post-peak strain energy conversion rate of the specimens decreased,indicating that the energy dissipation and release were slowed down by the freeze-thaw cycles.The final failure of the specimens was closely related to the energy conversion.The larger the energy storage limit and the post-peak strain energy conversion rate,the more significant the brittle failure of specimens.