复杂环境下深基坑的变形控制

Deformation Control of Deep Foundation Pit under Complicated Conditions

复杂环境下的基坑以控制基坑变形为设计和施工的关键。以杭州市彩虹大道市心路地道基坑工程为例,紧临已建地铁和高层住宅,而且有相邻基坑的土钉侵入其基坑范围内形成地下障碍物,建设环境较为复杂。针对土钉障碍物,先通过槽壁加固将土钉有效地固定住,成槽施工时利用抓斗的抓力直接切断土钉。实践表明上述清障方案效果很好。为控制基坑变形、减小基坑开挖对地铁和高层住宅的影响,采用了划分小基坑、坑内土体加固、对称开挖、设置隔离桩、设置应急降水井等多项保护措施。数值模拟分析与施工监测均表明,上述措施有效地控制了基坑变形,保护了周边环境的安全。其经验总结对类似深基坑工程具有参考价值。

The deformation control of foundation pit is critical for design and construction of foundation pit under complicated conditions.Taking the foundation pit project of Shixin Road Tunnel in Caihong Avenue of Hangzhou as an example,the article describes the construction of a foundation pit quite close to the built metro and high-rise residences,and the soil nails adjacent to the foundation pit entered into the range of pit to form underground barriers.The construction environment is more complicated.Aiming at the soil nail barriers,firstly,the slurry wall is reinforced to effectively fix the soil nails.The grabbing force of grab is used to directly cut off the soil nails during the grooving construction.The practice shows that the effect of the above barrier cleaning scheme is very good.In order to control the deformation of foundation pit and to decrease the influence of pit excavation on metro and high-rise residence,many protective measures of dividing small foundation pits,reinforcing soil within pit,implementing symmetry excavation,setting up isolation pile and constructing emergent dewatering well are taken.The numerical simulation analysis and construction monitoring show that these measures can effectively control the deformation of foundation pit,and protect the safety of surrounding environment.The successful experience can be referred for the similar deep foundation pit projects.