动态卸荷作用下节理围岩损伤过程研究

Study on Damage Process of Jointed Surrounding Rock Mass under Dynamic Unloading

为了探明节理岩体中的巷道爆破开挖后的卸载机理,为实际工程提供理论依据,本文基于离散元数值模拟方法,分析了考虑爆破荷载深埋矩形巷道节理围岩的损伤过程。结果表明:高地应力条件下,爆破开挖会在节理围岩中诱发显著的松动效应,导致洞壁附近形成远大于静态塑性区的动态松动损伤区,使得最终屈服区以外的节理面强度和渗透性等力学参数发生劣化;受爆破荷载的影响,岩体的回弹将产生较大的振动速度,达到m/s量级,是洞壁附近节理面损伤的主要来源;节理的组合方式也会对节理松动产生较大的影响,当节理夹角接近60°时,围岩最容易破坏。

In order to explore the unloading mechanism of jointed surrounding rock masses after blasting excavation and to provide the theoretical basis for actual projects, the damage process of jointed surrounding rock mass caused by dynamic unloading in blasting excavation was analyzed based on the distinct element method. It was proposed that the loosing effect was very remarkable, such that a loosing zone was formed in jointed surrounding rock mass, which was probably much larger than in the static plastic zone. As a result ,the mechanical parameters of joints in the loosing zone, such as the strength and permeability decreased greatly ; a large vibration velocity with a magnitude of m/s was produced by the rebounding of rock in blasting excavation which was an important damage resource of joints near the wall interference; the statement of joints sets had a great influence on the loosing of joints, and jointed surrounding rock mass was most likely damaged when the intersection angle was 60~.