打桩施工对周围土性及孔隙水压力的影响

INFLUENCE OF PILE DRIVING ON PROPERTIES OF SOILS AROUND PILE AND PORE WATER PRESSURE

假定土体为均质、各向同性的弹塑性介质,运用无限介质中圆柱形小孔和球形小孔扩张理论分别模拟饱和粘性土中打入桩的沉桩过程,求出沉桩过程中桩周土体的应力分布,分析沉桩引起桩周土体土性的变化及其对土体应力的影响。运用水力压裂理论推导出沉桩产生的超孔隙水压力在沉桩后瞬时沿桩身径向和竖向的分布。经与工程实测值作分析比较,发现理论预测值与实测数据吻合较好。

The process of pile driving in saturated clay is modeled by the theory of expansion of cylindrical and spherical cavities in an infinite medium. The soil is assumed as a homogenous,isotropic and ideal elasto-plastic material. Solutions are presented for the stress distribution of the soil around pile surface during pile driving. Changes of soil properties around pile surface and its effects on the soil stress due to pile-driving are analyzed. Using the theory of hydraulic fracture,radial and vertical distributions of excess pore water pressure are subsequently studied along the pile surface during and after pile driving. A comparison of predicted and observed values shows good agreement.