某软土深基坑险情分析与处理

Analysis and treatment of dangerous status of a deep foundation pit in soft clay

介绍一软土地区深基坑由于超挖引起基坑险情的工程实例。该基坑土层分布以淤泥质粉质黏土为主,为典型的长江漫滩地质条件,具有一定的代表性。基坑土方开挖期间,由于地下室方案调整,基坑深度加深,而未按设计要求对支护进行事先加固,导致基坑出现险情。通过对比前后不同挖深条件下支护结构的内力及变形,分析了险情产生的原因,并依据实测支护结构和周边环境的变形,针对基坑出现的问题提出有效的处理措施,从而保证了基坑的安全。

An engineering example that a deep foundation pit is in dangerous status caused by over excavation in soft clay is described. The soil layers mainly including mucky silty clay is typical and representative floodplain of the Yangtze River. During pit excavation, the depth of foundation pit increases because the basement project is adjusted, meanwhile the retaining structure is not reinforced in advance, which does not satisfy the design requirements, so as to lead to dangerous status of the pit. Through comparing the internal force and the displacement of retaining structures at different excavation depth conditions, the reasons why the dangerous situation occurs are analyzed. Based on the deformations of retaining structures and surroundings, the effective treatments according to the foundation pit problems are proposed to ensure the foundation pit safety.