基于地应力场加卸载的地下洞室稳定模型试验研究

加卸载响应比理论是研究非线性系统稳定的一种重要方法。本文分析了该理论的本质含义,研究了该理论在洞室稳定分析中存在的问题,提出了基于应力边界值即地应力场增减实现加卸载的方法。文中以某矿山巷道稳定研究作为工程背景,建立了相似材料平面应变模型。通过对顶部边界应力进行逐级加卸载,主要研究了拱顶竖向压力、拱顶沉降和声发射的响应特征。结果表明,当应力不太大时,拱顶竖向压力和拱顶沉降的加卸载响应比值接近1;当围岩接近破坏时,比值出现突然的增加,并伴随较大的波动。声发射能量和事件数虽未出现类似特征,但总体来说,随着荷载的增加,声发射呈现增加的趋势。

Model Experimental Study of Underground Cavern Stability Based on Load/Unload of In-Situ Stress Field

The load/unload response ratio (LURR) theory is one of the important methods to study the stability of nonlinear system.In this paper,the essential meaning of the theory is analyzed,and the problems existing in the underground cavern stability analysis are studied.Based on stress boundary value (i.e.in-situ stresses) increase/decrease,a method to realize in-situ stress field loading/unloading is proposed.Taking the stability study of a mine tunnel as the engineering background,a plane strain model of similar material was established.Through step by step loading and unloading to top boundary stress,the vertical pressure on cavern crown,the crown settlement and the response characteristics of acoustic emission were studied.Results show that when the stress is not too large,both LURRs of vertical pressure on cavern crown and crown settlement are close to 1;whereas,when surrounding rock is close to destruction,the ratio suddenly increases and is accompanied by a larger fluctuation.Although there is no similar feature of acoustic emission energy and event number,but generally speaking,with the increase of load,the acoustic emission increases.