渗流作用下河岸深基坑支护结构稳定性分析

河水径向渗流会对河岸基坑稳定性及支护结构内力产生显著影响。以某深基坑工程为背景进行了三维流固耦合数值模拟分析,研究了渗流对深基坑土体及支护结构受力与变形的作用规律。研究结果表明：1初始水位时,渗流作用对土体水平应力与土体剪应力的影响较小,但水位上升后,坑底处土体水平应力明显增大,在坑壁拐角处应力集中现象突出,土体剪应力在开挖面以下的底脚处最大;2土体水平位移与竖向位移均在水位上升时呈递增趋势;3桩身弯矩与剪力在水位上升初期有较大增加,之后增长速度减小;4上层、下层锚杆的自由段和锚固段轴力在水位上升初期均有明显增加,但之后增加幅度很小;5安全系数在水位上升初期降低较多,之后以较小速度呈线性减小。

Study of Supporting Structural Stability for Riverbank Deep Foundation Pit under Seepage

When riverbank deep foundation pit is excavated,the river radial seepage will have significant impact on the stability of deep foundation pit and supporting structure. For exploring the law of seepage during the excavation of riverbank deep foundation pit,the numerical simulation analysis is used for a deep foundation pit engineering. A three-dimensional model for coupling problem of seepage and stress fields is established. The results reveal the force and deformation law of the surrounding soil of the pit and supporting structure with the seepage in the deep foundation pit. The results show that： 1 at the initial water level,the effect of seepage on horizontal stress and shear stress of surrounding soil is small,but when water level rises,horizontal stress in soil at pit bottom significantly increases,stress concentration is outstanding at the corner of pit wall,and the largest value of shear stress appears beneath the corner of the pit; 2 the horizontal and vertical displacements of surrounding soil monotonously increase when the water level rises; 3 the pile moment and shear force increases obviously in the early stage of water level rising,and then level off; 4 axial force of free and anchorage section of the upper and lower anchors increases significantly in the early stage of water level rising,and then level off; 5 the coefficient of safety has a great reduce in the early stage of water level rising and then decreases linearly with a small rate.