岩溶地区桥墩桩基钢护筒变形加固处治技术

Reinforcement treatment of deformation of steel casing of bridge pile foundation in karst area

本文以大王山矿坑工程中桥墩桩基钢护筒变形事故为研究背景,通过理论分析与现场实际相结合,展开了岩溶地区桥墩桩基础钢护筒变形处治与力学分析研究,其主要研究结论如下:(1)桩钢护筒变形处理采用气切割钢护筒和千斤顶孔内校正变形法,并以内支撑、C30高流态混凝土填充、注浆加固辅佐;(2)型钢内撑采用80 mm×80 mm×2.5 mm矩形钢管,环向布置分为3个三角形,竖向设置间距以0.5 m为最优;(3)桩周预埋8根注浆小导管以及4根小导管向上倾斜插入溶洞内注浆,注浆加固效果明显;(4)气切割法逐层切割,每层切割高度50 cm,环向划分为3块进行切割,并用2 cm厚钢板弯制成2个半圆,焊接封闭成环。本项目研究内容可为类似工程提供理论和实践支持。

The deformation treatment and mechanical analysis of the steel casing of the pier pile foundation in the karst area are carried out in this paper in the context of the deformation accident of the steel casing in the pile foundation of the Dawangshan mine pit project through theoretical analysis combined with the actual project situation. The main conclusions are as follows:(1) The deformation treatment of the pile steel casing adopts the gas cutting steel casing and the correction deformation method in the jack hole. It is supported by internal support, C30 high-flow concrete filling and grouting reinforcement .(2) The steel inner support adopts 80mm×80mm×2.5mm rectangular steel pipe, and the circumferential arrangement is divided into three triangles, and the vertical spacing is 0.5m.(3) The eight small grouting pipes and four small pipes are embedded in the piles and inserted into the caves to grout. The grouting reinforcement effect is obvious.(4) The gas cutting method is performed by cutting layer by layer. The cutting height of each layer is 50cm,with the ring direction divided into three pieces for cutting, the two semicircles bent by 2cm thick steel plate, and the welding closed into a ring. The research content of this project can provide theoretical and practical engineering support for similar projects.