土方超挖诱发桩锚支护基坑失稳过程分析

Pile-anchor Retaining Foundation Pit's Unstable Failure Case Induced by Overbreak

土方开挖过程中超挖现象极易诱发基坑失稳破坏,严重威胁基坑的安全。结合某桩锚支护基坑由于超挖引起失稳破坏的实例,基于M-C破坏准则,分析不同土方超挖深度条件下基坑变形特征及基坑失稳破坏过程。结果表明:土方超挖过程中,支护结构顶部优先于基坑底部发生失稳破坏。且基坑底部易发生踢脚现象。超挖深度在2.5 m以内时,位移变化速率较慢,当超挖深度达2.5 m时,位移增量急剧增加。随着超挖深度的变大,位移增量减小,但总位移量在不断增加。

During excavation of earthwork,overbreak was very easily to induce destabilization of foundation pit,posed a serious threat to its security.Combined with a specific example that a pile-anchor retaining foundation pit's unstable failure cause by overbreak.Based on M-C rupture theory,analyzed the influences of different overbreak depths to deformation and feature of foundation pit.The results showed that,during overbreak of earthwork,supporting structure's top is easier being destabilized than foundation ditch's bottom,and,kick strip phenomenon easily appeared near bottom of foundation ditch.When overbreak is within 2 m,displacement increased slowly,when overbreak reached 2.5 m,displacement increased sharply.With the increase of overbreak,displacement increment decreased,but total displacement grew sustainedly.