长屿硐天“钟”形采空硐室结构特点及工程意义

摘要

Cavern shape and surrounding rock structure are the important factors to cavern stability.In this work,the shape,surrounding rock structure,and rock strength of the deserted bell-shaped caverns without support in Changyu,Wenlin,Zhejiang province were investigated.Then the cavern stability with different shapes,span-depth ratios,inclination angles of sidewall was calculated and analyzed utilizing FLAC.It is shown that the bell-shaped cavern is better than other shaped caverns,such as rectangular cavern,circular cavern and a type of cavern with straight wall and top arch,because the tensile stress area of surrounding rock is smallest and the surrounding rock is more stable with high compressive strength.The smaller the span-depth radio,the smaller tensile stress area of surrounding rock and the more stable the cavem chamber.When the span-depth radio is less than 1.33,there is no tensile stress area on the top of the surrounding rock,which is favorable to the surrounding rock stability.With the decreasing of the inclination angle of sidewall,the tensile stress areas first decrease and then increase.When the inclination angle of sidewall ranges between 70° and 80°,the tensile stress area of surrounding rock is small,which is favorable to the surrounding rock stability.In site investigation,75％ of the caverns has the span-depth ratio less than 1.33,while 60％ of sidewall angles are between 70°and 80°.%硐室形状及围岩结构是影响硐室稳定的重要因素.以浙江温岭长屿废弃矿山“钟”形采空、无支护硐室为研究对象,在勘明采空硐室形状其围岩结构类型和岩石强度的基础上,采用FLAC有限差分方法对不同形状、不同跨高比、不同硐壁倾角的硐室围岩进行了稳定性计算与分析,结果表明:“钟”形硐室优于矩形、圆形和直墙拱硐室结构,其围岩受拉区面积最小,更能发挥岩体抗压能力强的优点;跨高比越小,围岩受拉区面积越小,硐室越稳定,跨高比≤1.33时,硐室顶部围岩不出现受拉区,对围岩稳定性比较有利;硐壁倾角对围岩受拉区面积的影响呈先减小后增大的规律,当侧墙倾角70° ～80°之间时,硐室围岩受拉区面积较小,对硐室稳定性最为有利;实际勘查中发现,75％的硐室跨高比小于1.33,60％的侧墙倾角集中在70° ～80°之间.