频繁爆炸荷载下岩体累积损伤效应及演化模型研究

The accumulative damage effect of reserved rock mass is very significant under frequent blasting loads. However, the existing level of research lags far behind the project application. There are following disadvantages in current model, some parameters of the models have no clear physical meaning, the application conditions of models subject to strictly limit and the simulation of damage can only be carried out in a single explosion case. This topic relied on the major projects, the laboratory test, the in-situ test, the theoretical analysis and the numerical simulation are combined, to explore the establishment of a new model for the accumulative damage of the rock. Based on the consistency of damage and acoustic emission, given the damage variable and acoustic emission probability density function from acoustic emission, and built the damage evolution model of rock material in quasi-dynamic conditions. The evolution of accumulated damage and the main controlling factors are revealed in advancing, to-and-fro, frequent blasting dynamic load. the accumulative damage model is established when the main controlling factors only are considered. The calculation procedure of the theoretical model be written, and carried out numerical simulation to verify the model. The research results will improve the theoretical level of the rock accumulative damage, it is great significant for underground blasting safety control and rock dynamic instability.

频繁爆炸荷载作用下，预留岩体的累积损伤效应非常显著，然而现有的研究水平严重滞后于工程应用。针对目前模型中广泛存在的只进行单次爆炸情况下损伤的模拟、模型中某些参数无明确的物理意义、理论模型的应用条件严格等缺陷，本课题以重大工程为依托，采用室内试验、现场原位测试、理论研究和数值计算相结合的方法，探索建立岩体累积损伤的新模型。以损伤与声发射的一致性为基础，给出基于声发射的损伤变量和声发射概率密度函数，建立准动态条件下岩石材料的损伤演化模型，揭示推进式往复频繁爆炸荷载作用下岩体的累积损伤效应及主控因素，建立仅考虑主控因素的岩体累积损伤演化模型。编写理论模型的计算程序，对依托工程开展数值仿真验证。研究成果将提高岩体累积损伤的理论水平，对地下工程的爆破安全控制和岩体动力失稳有重要意义。

通过髙应变率下的单轴压缩和循环加卸载试验，建立基于声发射信号累计振铃数的岩石损伤演化方程，并将模型计算结果同试验结果比对，两者具有较好的一致性。结合大帽山大断面隧道群的现场声波监测，研究推进式往复爆破作业的双侧壁导坑法施工的大断面隧道的围岩累积损伤范围，声波监测结果表明，在推进式的多次爆炸荷载作用下，围岩将产生一定程度和范围的损伤；侧壁围岩的累计损伤范围主要由与其齐平的导洞I的开挖掌子面爆破决定；其损伤范围随着导洞I开挖掌子面的接近而逐渐增大，当两者齐平时围岩的损失范围达到最大，得到最大爆炸荷载是岩体损伤范围的主控因素；但当导洞I开挖掌子面逐渐远离和导洞III爆破开挖通过时，围岩的损伤范围并没有扩大，仅导致损伤围岩的损伤程度增大，爆炸次数是岩体损伤程度的主控因素。基于室内试验、工程岩体现场原位测试和岩体的等效体积拉应变理论，构建了新的岩体累积损伤演化模型。在模拟推进式往复爆破荷载作用下围岩的损伤范围时，用与监测断面齐平的单次爆破近似表示推进式的多次爆破，实现数值模型的计算。通过与声波监测结果对比，此方法可以较好地模拟推进式往复爆炸荷载作用下围岩的累积损伤范围，并可为类似工作提供参考和借鉴。