上海深厚砂层旋挖桩成孔实测及数值分析  

Measurement and Numerical Analysis of Drilling Holes for Rotary Excavation Pile in Deep Sand Layer in Shanghai

作　　者：邵治理 SHAO Zhili(Shanghai Mechanized Construction Group Co.,Ltd.,Shanghai200072,China)

机构地区：[1]上海市机械施工集团有限公司,上海200072

出　　处：《施工技术（中英文）》2024年第19期30-34,共5页Construction Technology

基　　金：上海市“科技创新行动计划”启明星项目(扬帆专项)(23YF1436800)。

摘　　要：当前灌注桩成孔稳定计算多采用压力平衡法,将泥浆护壁效应等效为泥浆静水压力以平衡外侧水土压力,泥浆静水压力常简单考虑为泥浆重度与深度的乘积。相关研究表明,泥浆护壁效应与地层性质和泥皮质量相关,砂性土层中泥皮质量主要受泥浆黏度影响,因此泥浆压力平衡法应当将泥浆黏度作为计算参数。以上海某超大型铁路枢纽桩基工程为分析案例,场地地层为上覆黏土下卧砂层分布,成桩深度内黏土厚度30m、砂层厚度达到50m,试成孔过程中发生地表孔口塌陷和深层砂性土体缩径。基于变形实测结果,建立了同时考虑泥浆重度和黏度的成孔稳定性数值计算方法,对比实测结果验证了考虑黏度参数的必要性,进一步研究了各泥浆指标对成孔稳定性的影响。Currently,the pressure balance method is mostly used in the calculation for hole-forming stability of cast-in-place piles.The slurry wall protection effect is equivalent to the slurry hydrostatic pressure to balance the external water and soil pressure.The slurry hydrostatic pressure is often simply considered as the multiplication of the slurry weight and depth.Relevant studies have shown that the slurry wall protection effect is related to the formation properties and mud quality.The mud quality in the sandy soil layer is mainly affected by the slurry viscosity.Therefore,the mud pressure balance method should adopt slurry viscosity as a calculation parameter.Taking the pile foundation project of a super-large railway hub in the Shanghai coastal area as a case for analysis,the site stratum is the distribution of overlying clay and the underlying sand layer.The thickness of the clay layer is 30m,and the thickness of the sand layer is 50m in the depth of pile forming.Surface orifice collapse and deep sand soil shrinkage occurred during the trial pore-forming process.Based on the measured results of deformation,a numerical calculation method for pore-forming stability considering both slurry density and viscosity was established.The necessity of considering viscosity parameters was verified by comparing the measured results.The influence of each slurry index on pore-forming stability was further studied.

关 键 词：车站 桩基础 旋挖桩 泥浆护壁 稳定性 数值模拟 监测 

分 类 号：TU753.3[建筑科学—建筑技术科学]