双溶洞建筑边坡变形破坏模型试验研究

An Experimental Study on the Slope Deformation and Collapse with Double Karst Caves

以某岩溶地区建筑边坡为工程背景,将建筑物荷载简化为坡顶荷载,根据相似材料原理,建立上下布置双溶洞相似材料平面应变模型;采用三阶段荷载模式,即预加载模拟建筑物荷载、模拟开挖和继续加超载直至边坡整体破坏,研究溶洞顶板沉降、靠近坡面溶洞洞壁中部水平位移、坡体内岩体压力和分层开挖坡面位移变化特征。研究结果表明:溶洞顶板位移在整个过程中呈增加趋势,在第三阶段出现急剧增加特征。近坡面一侧溶洞洞壁中部水平位移在第一阶段均呈缓慢增加趋势;在第二阶段上溶洞受开挖扰动的影响水平位移呈现急剧跳跃态势,下溶洞水平位移突然增加而后稳定;第三阶段上溶洞水平位移出现急剧增加然后跌落特征,下溶洞水平位移基本无变化。在整个试验过程中岩体压力呈增加态势,且近坡面处压力增幅较大。在第一、二阶段,边坡沿高度方向坡面水平位移呈中间大两头小的中鼓增加态势,而在第三阶段,坡面底部出现挤出效应而出现水平位移明显增大特征。

With the background of slopes with building loads in karst areas,wherethe building loads are to be simplified as loads on the top,and based on similar material theory,a similar material plane strain model of double karst caves has been built,with double caves laid out from top to bottom,and a three-stage load procedure has been proposed for the preloading,simulation of slope excavation and an overloading involving slope collapse.A research has been carried out on the roof deflection(RD)of karst caves,as well as the horizontal displacement in the middle of sidewall close to the slope surface(HDMS)of double caves,the rock pressure(RP)and the horizontal displacement of layered slope surface(HDLS)formed by excavation.The research results show that:in the whole process,RD shows an increasing trend,especially with a dramatic increase at the third stage;at the first stage,HDMS show a slowly-increasing trend,with a sharp fluctuation with HDMS at the top cave at the second stage,and with a constant sharp increase with HDMS of the bottom cave at the third stage.HDMS of the top cave rises rapidly and then drops quickly,whereas HDMS of the bottom cave exhibits little change.Rock pressure(RP)is increased in the whole test process,with a more remarkable increase close to the slope surface;at the first and second stages,a slow increase trend of HDLS is exhibited in a similar parabolic form;and at the third stage,HDLS increases markedly,showing an extrusion effect at the bottom of the slope surfaceat the third stage.