岩爆的洞室效应

The chamber effects of rock burst

岩爆是高地应力区地下工程开挖中常见的一种地质灾害。目前岩爆的发生条件多从地应力条件、地层岩性、岩体结构、埋深和地形、地质构造作用、水文地质条件、开挖爆破等因素开展研究。文章提出通过改变洞室断面形态及尺寸预防岩爆发生的思路,在单因素分析条件下,通过有限元软件模拟不同洞室形状和尺寸的开挖,分析探讨同一尺寸、不同洞室形状下的岩爆强度和同一洞室形状、不同尺寸下的岩爆强度。结果表明:岩爆存在洞室形状效应,同一尺寸下,椭圆(谐洞)是对减少岩爆最有利的洞形,半圆直墙形和圆形其次,半圆形最差;岩爆存在洞室尺寸效应,同一洞室形状下的岩爆都随洞室开挖尺寸的增大而增强。同时,通过双曲线和指数函数的拟合表明,岩爆强度不会无限上涨,而是最终趋于一个稳定值。

Rock burst is a type of geological hazard on constructing underground engineering in the high crustal stress area, currently, research about rock burst usually fall on the factors such as crustal stress, rock character, rock mass structure, depth of burial and land form, geologic structure, hydrologic geology, excavation and blast. The paper puts an idear of reducing rock burst by changing chamber＇ s shape and dimension, on the condition of one factor analysis, it simulates chamber excavation in the variant chamber shape and dimension by finite element software, and analyses rock burst＇ s intensity about same dimension but different shape and same shape but different dimension. The result indicates that rock burst have chamber shape effect, in the same chamber dimension, the harmonic chamber is best chamber shape for reducing rock burst, the next one is hemicycle stalk and circle, hemicycle is the worst shape; rock burst have chamber dimensional effect, rock burst of same chamber shape shall be enhanced with enlarging the chamber dimension, at the same time , by hyperbolic and exponential function fitting, it indicates rock burst＇s intensity doesn＇t rise unlimited, but ultimately driving to a stable value.