人工挖孔托换桩在湿陷性黄土地基事故处理中的应用

APPLICATION OF UNDERPINNING PILE BY MANUAL DIGGING IN TREATMENT OF COLLAPSIBLE LOESS FOUNDATION ACCIDENT

某单层工业厂房,所在场地为高填场地。由于设计时地基处理不当,导致建筑物在使用后墙体和地面出现裂缝,在室内、外地面上近南北走向,缝宽约2 cm;墙体裂缝为张性剪裂缝,主要分布于厂房西部墙体,倾向以东为主。存在严重的安全隐患。为使厂房变形得到有效控制,经研究后决定采用人工挖孔托换桩加固方案。以此工程为例,提出托换桩设计公式;详细介绍托换方案的选定、人工挖孔托换桩的设计方法、施工工艺、监测、控制以及施工中的技术难点和对策。经过托换施工后,使该厂房被托换部分的沉降趋于稳定,厂房基本上恢复正常使用。经过半年来的变形观测表明,在黄土地区采用人工挖孔托换桩法加固类似工程问题是可行的。

A single story industrial building in Xi＇an is positioned on a high-filled ground.Because the designer adopted unsuitable ground treatment method,so cracks occurred on the wall and the floor,whose width was about 2.0 centimeter inside and outside of the ground which were nearly SN direction;the extensional fracture was mainly on the west of building,which was a serious hidden danger of the building.The scheme of rectifying deviation by underpinning pile was employed after investigation for sake of safety.Based on which the following aspects were investigated： the formula to determine the numbers of underpinning piles for rectifying the leaning building was presented;scheme choice of rectifying deviation,designing method,construction procedure of underpinning pile,jacking monitoring and controlling were introduced in derail;difficult factors and corresponding problems during jacking construction were provided.After reinforcement construction,the settlement of the building tended to stabilization and the normal operation of the workshop was restored.After deformation observation for 6 months,it can be concluded that underpinning pile by manual digging is feasible to reinforce similar structures and project in loess region.