对门寨隧道DK34+164处隧底大型溶洞处理技术研究

对门寨隧道DK34+164处隧底发育大型半充填型溶洞,溶洞深44 m,宽度38 m,纵向轴长189 m,容量超过30.0×10^4 m^3,溶洞规模宏大,整体呈条带状分布,溶洞大厅底部暴雨时为一水塘,溶壁可见明显水流痕迹。本文结合本溶洞规模、工程水文地质条件,对比分析了"弃渣+C20砼"分层回填方案、混凝土圬工回填方案及桥梁跨越方案,经过综合比选,设计采用"弃渣+C20砼"分层间隔回填方案。"弃渣+C20砼"分层分隔回填方案既满足了沉降控制标准,又通过弃渣透水层与C20砼分层分隔回填较好地解决了地下水的引排及大体积混凝土因水化热导致有害裂缝的问题。在溶洞处理完毕经历了10个月放置期后,对本隧底大型溶洞段工后沉降进行了监测,数据显示沉降变形已基本趋于稳定,可满足施作二衬及铺设道砟条件。

Study on Treatment Technology for Large Karst Cave of Duimenzhai Tunnel at the Bottom of DK34+164

A large semi-filled karst cave developed at the bottom of DK34+164 of Duimenzhai Tunnel is 44 m deep and38 m wide,with a 189 m longitudinal axis and a capacity of 30.0×10^4 m^3.This karst cave is large and distributed in a stripe as a whole.There is a pond formed at the bottom of karst cave hall and there are visible traces of water flow in the cave wall.Based on the size of karst cave and the engineering hydrogeological conditions,this paper compared and analyzed the three schemes of"waste slag+C20 concrete"layered backfilling scheme,and concrete masonry backfilling scheme and bridge spanning scheme.After comprehensive comparison,the design adopted the"waste slag+C20 concrete"layered interval backfilling scheme.The"waste slag+C20 concrete"layered interval backfilling scheme not only satisfied the settlement control standards,but also solved the problem of groundwater drainage and harmful cracks of mass concrete due to heat of hydration by use of waste slag permeable layer and C20 concrete layered interval backfilling.After the karst treatment had been completed and placed for 10 months,the post-construction settlement of the large karst cave section at the bottom of the tunnel was monitored.The data showed that the settlement deformation had basically stabilized,which could meet the conditions of applying the second lining and laying the ballast.