循环爆破开挖下隧道围岩振动效应与损伤演化的模型实验

针对推进式循环爆破开挖下隧道围岩振动效应与损伤演化问题，按照相似比理论进行模型实验研究，实验模型采用1:15比例浇筑制成。通过模拟隧道推进式循环爆破开挖方式，以同一测点处爆破前后岩体声速变化评价隧道围岩损伤程度，探寻爆破参量变化对振动效应的影响，探索围岩损伤演化与爆破次数之间的关系。研究结果表明:在最大段药量大致相同情况下，起爆段数对萨道夫斯基公式的介质系数K影响很小，而对萨道夫斯基公式的衰减系数α影响较大；隧道在推进式循环爆破开挖下，同一深度距离爆区相同的测点，其声速降低率存在较大差异，围岩的爆破损伤范围在深度和广度方面均具有典型的各向异性特征；当爆炸参量基本相同时，不同循环爆破开挖下测点的累积声速降低率呈非线性增长趋势；在推进式循环爆破加载下，围岩爆破累积损伤量D与爆破次数n之间存在非线性演化特性，不同的测点具有各自的爆破累积损伤扩展模型，距离爆源越近爆破损伤扩展越快，围岩爆破累积损伤效应具有典型的非线性演化特性和各向异性特征。

Model experimental studies of vibration effect and damage evolution of tunnel's surrounding rock under cyclic blasting excavation

In this work, based on the similarity theory, we conducted a model experiment to study the vibration effect and damage evolution of rocks surrounding a tunnel in push-type cyclic blasting excavation. The model was constructed with a ratio of 1: 15. By simulating the tunnel excavation of push-type cyclic blasting, we explored the influence of the change of blasting parameters on the vibration effect. The degree of the damage of the surrounding rock was evaluated by the change of the acoustic velocity at the same measuring point after blasting. The relationship between the damage evolution of the surrounding rock and the times of blasting was established. We arrived at the following results: (1) When the maximum section dose was about the same, the influence of the initiation section number on the dielectric coefficient (K) of Sodev formula was very small, but it was great on the attenuation coefficient of Sodev formula; (2) In push-type cyclic blasting excavation, there was a great difference in the decrease rates of the acoustic velocity among the measuring points with the same distance to the blasting region at the same depth, and the blasting damage ranges of the surrounding rock were typically an isotropic in terms of both depth and width; (3) When the blasting parameters were basically the same, the growth trend of the cumulative acoustic velocity's decrease rate at the measuring point was nonlinear in different cyclic blasting excavation; (4) There were nonlinear evolution characteristics between the blasting cumulative damage (D) of the surrounding rock and the times of blasting (n) under push-type cyclic blasting loading, and different measuring points had different blasting cumulative damage propagation models. The closer the measuring point was to the explosion source, the faster the cumulative damage extension. Blasting cumulative damage effect of the surrounding rock had typically nonlinear evolution properties and anisotropic characteristics.