圆形巷道两帮水平切槽对围岩卸压的数值分析

处于深部高应力的岩体中储存有大量的弹性应变能,它是引发深部硬岩巷道发生岩爆的内因。卸压法可以用于改变巷道和洞室附近围岩的应力场,使这部分围岩处于应力降低区,从而达到保持其稳定性的目的。本文用岩石破裂过程分析RFPA系统模拟圆形巷道周边开卸压槽前后巷道围岩的变形、损伤与破坏过程,分析了不同原岩应力状态(侧压力系数)和切槽长度条件下围岩的应力和损伤区的分布特征,揭示了围岩中开槽卸压的力学机理。数值模拟结果表明,数值模拟证实了当卸压槽深度为巷道直径的0.5倍左右时,围岩的卸压效果明显,但过长的卸压槽长度会导致整个巷道围岩结构体的承载力降低和变形过大。该项研究对于巷道卸压的工程实践具有一定的理论指导意义。

Numerical Simulation on De-stressing with Horizontal Groove at the Two Sidewalls around Circular Underground Opening

A large number of elastic strain energy is stored in highly stressed deep rock mass, which may be the main cause of rockburst happened in hard-rock deep mining. The essence of destressing method, which is different from conventional reinforcement method, is to improve stress condition in surrounding rock, thus to maintain the stability of the underground openings. The Rock Failure Process Analysis (RFPA) code is used to analyze the damage and failure process of underground opening. The stress condition and damage development in surrounding rock under different in-situ stress conditions (lateral pressure coefficient) and groove geometries is examined based on the numerical simulations; the rock failure mechanism during the destressing by cutting horizontal grooves at the sidewalls of underground opening is clarified. The numerical results indicated that, the destressing groove may play an important role in relieving the stress concentration around the opening when its length is about 0.5 times the diameter of the opening, however, the increase of groove length may also lead to the decrease of load-bearing capacity and increase of surrounding rockmass deformation. This numerical study may provide theoretical guide for the design for layout of destressing to prevent rockburst in underground opening.