软基处理PST桩复合地基加固机理及CPTU验证  

Strengthening mechanism of PST pile composite foundation in treatment soft soil foundation and CPTU experimental verification

作　　者：李伟 Li Wei(Hubei Province Wantai Geotechnical investigation and Design Company,Yichang Hubei 443000,China)

机构地区：[1]湖北万泰岩土勘察设计有限公司,湖北宜昌443000

出　　处：《山西建筑》2024年第11期76-80,85,共6页Shanxi Architecture

摘　　要：对于厂房、仓库、露天堆场等沿海软土地基加固处理工程,采用传统的软基处理方法如真空预压或堆载预压,其施工工期长、工后沉降大;采用水泥搅拌桩由于施工质量不易控制,桩体强度低、处理效果不佳;采用刚性桩复合地基存在地面堆载沉降不均匀等难题。“PST”复合地基处理方法采用预制桩与桩帽及厚褥垫层组合,将预制桩的高承载力转化为褥垫层均布承载力;地面均布荷载引起的变形应力传递到桩身而非其下的软土。以某大型地基处理工程为例,通过CPTU孔压静力触探技术评价PST桩地基处理加固效果与挤土效应,通过对打桩过程中,不同时期的超静孔隙水压力进行观测,掌握超静孔隙水压力消散和变化规律。通过打桩过程中的超孔压的变化情况,分析打桩顺序和速率对孔压的影响程度,了解PST桩施工对软土的扰动规律,以指导施工,降低PST桩施工对地基土的影响。For the reinforcement and treatment works of coastal soft soil foundation such as workshop,warehouse and open storage yard.Traditional soft foundation treatment methods,such as vacuum preloading or surcharge preloading,have long construction period and large post construction settlement;the cement mixing pile has low strength and poor treatment effect because the construction quality is not easy to control;using rigid pile composite foundation has some problems,such as uneven ground surcharge settlement and so on.The“PST”composite foundation treatment method adopts the combination of precast pile,pile cap and thick cushion to transform the high bearing capacity of precast pile into the uniformly distributed bearing capacity of cushion layer;the deformation stress caused by the uniformly distributed load on the ground is transmitted to the pile body rather than the soft soil under it.Taking a large-scale foundation treatment project as an example,CPTU pore pressure static penetration test technology is used to evaluate the reinforcement effect and soil compaction effect of PST pile foundation treatment.Through the observation of excess pore water pressure in different periods during pile driving,it is of great engineering significance to master the dissipation and variation law of excess pore water pressure.Through the change of excess pore pressure during pile driving,analyse the influence degree of pile driving sequence and rate on pore pressure,and understand the disturbance law of PST pile construction on soft soil,so as to guide the construction and reduce the impact of PST pile construction on foundation soil.

关 键 词：软土地基 PST桩复合地基 CPTU孔压静力触探 超静孔隙水压力 

分 类 号：TU447[建筑科学—岩土工程]