基于损伤-虚拟张拉裂纹模型的地下爆炸围岩破坏规律研究

地下硐室作为爆炸危险物的隐蔽贮藏空间，有潜在的内爆炸风险。为研究内爆炸作用下硐室围岩的动态响应机制，提出了一种基于岩石HJC (Holmquist-Johnson-Cook)模型和节理内聚力单元的损伤-虚拟裂纹模型。分析了模拟方法的可靠性，并在此基础上，通过多物质ALE算法对球形硐室内爆炸过程进行数值模拟，分析了围岩损伤范围和分区破坏规律。研究表明:插入内聚力单元弥补了HJC模型无法模拟低静水压力下张拉破坏的不足，且尺寸效应易于处理。模拟方法同时考虑了岩体内张拉裂纹的扩展和岩石材料的塑性损伤，能够真实地反映岩石破坏的全过程。以红砂岩为例，根据数值模拟结果，填实（耦合装药）爆炸时围岩分区破坏规律明显，破碎区比例半径为0.26 m/kg1/3、裂隙区比例半径为0.47 m/kg1/3。随着硐室尺寸的增大，空气的间隔作用可以减小爆炸荷载对围岩的损伤作用，比例半径达到0.52 m/kg1/3时，可以实现爆炸荷载的完全解耦。

Failure law of surrounding rock under underground explosion based on a new damage-virtual tensile crack model

As a hidden storage space for explosive hazards, the underground cavern has a potential risk of an internal explosion. To study the mechanism of the dynamic response of the surrounding rock under an internal explosion load, a new coupled damage and virtual crack model based on the HJC (Holmquist-Johnson-Cook) constitutive model of rock and the tensile failure cohesion element of the joint is proposed. And the quasi-static uniaxial compression, Brazilian splitting experiments, and dynamic SHPB experiments were calibrated. Therefore, this model is available for the simulation of middle-high strain rate problems, such as an underground explosion. Based on the new method, a series of underground explosions in spherical caverns is simulated by the multi-material ALE algorithm. The damage range and zoning failure law of the surrounding rock are analyzed. The research shows that the insertion of cohesive elements compensates for the deficiency of the HJC materials which cannot simulate tensile failure at low hydrostatic pressure. And the size effect of the model proposed in the paper is easy to deal with. The new method in this paper considers both the propagation of tensile crack by cohesive elements and the plastic damage by the HJC model, which can reflect the failure process of rock more accurately and completely. According to the numerical simulation results, the failure law of red sandstone during filling (coupling charge) explosion shows zonal characteristics with crashed zone and fracture zone from inside to outside. The proportional radius of the crashed zone is about 0.26 m/kg1/3, and that of the fracture zone is 0.47 m/kg1/3. The existence of the air chamber changes the loading form and reduces the load intensity acting on the cavern. Therefore, with the increase of the chamber size, the interval effect of air can reduce the damage of the surrounding rock during the explosion. Taking the red sandstone as an example, when the proportional radius reaches 0.52 m/kg1/3, there was no damage and no fracture generated by the explosion load. The conclusions above can be used as guidance for the anti-explosion design and protection of underground works.