溶洞顶板极限承载力研究

Study on ultimate bearing capacity of upper rock plate of karst cave

针对国标《工程岩体分级标准》[1]中Ⅲ、Ⅳ类岩体条件,采用显式有限差分法,对岩溶地区扩大基础下椭球状溶洞顶板稳定性进行了分析。通过对溶洞顶板的应力和位移变化规律及塑性区演化规律研究,得出在两种岩体条件下不同溶洞跨度和顶板厚度时溶洞顶板的极限承载力,绘出了溶洞跨度、顶板厚度对极限承载力的联合影响曲面。溶洞顶板的极限承载力随溶洞跨度的增大而减小,随溶洞顶板厚度的增大而增大。在其他条件相同时,Ⅳ类岩体的溶洞顶板极限承载力仅为Ⅲ类岩体的1/3左右。

FLAC3D is applied to analyze the stability and the ultimate bearing capacity of upper plate of karst cave under the loading of rectangular spread foundation; and two typical types of rock mass are studied. The ultimate bearing capacity of upper plate of karst cave in various engineering conditions are presented by analyzing the characteristics of rock stress and displacement and the whole evolvement process of plastic zones in the upper plate. The results show that the ultimate bearing capacity increases with the increasing of the thickness of upper plate and decreases with the increasing of the width of karst cave. In the same conditions, the ultimate bearing capacity of rock Ⅳis only one third of rock Ⅲ.