渗水作用下膨胀土中单桩承载变形特性研究

目前膨胀土中桩基设计仍基于非膨胀土力学的设计原则。基于FLAC3D采用热-力耦合方法实现吸热膨胀来模拟膨胀土的吸湿膨胀,并重点阐述温度场模拟湿度场的关键参数取值方法。建立膨胀土中单桩三维实体模型,得出渗水作用下膨胀土中单桩的荷载变形特性、桩侧摩阻发挥特征,并分析了桩长、桩径、膨胀系数等对单桩承载特性的影响规律。研究结论:非扩底桩最小桩长宜大于2倍膨胀影响深度;细长桩比短粗桩更能有效降低膨胀土中桩顶的位移。该方法可获得渗水作用下任一时刻的桩身受力变形特性,为研究膨胀土中桩基受荷性能提供一种可行的变通手段。

Research on Bearing and Deformation Characteristics of a Single Pile in Expansive Soil Under the Action of Seepage

The existing problem is that the design principle of pile foundation in expansive soil foundation still fllow the design prineiple of non-expansive soil mechanics.Based on FLAC^3D,the thermal-mechanical coupling method is used to simulate the lhygroseopie expunsion deformation of expansive soils.The method of key parameters of temperature field simulation humidity field is given.A three dimensional solid model of single pile in expansive soil is established.The load-deformation churncteristics and the frictional resistance of single pile in expansive soil under seepage are obtained.The inluence of pile length,pile diameter,expansion cofficient on the bearing charateristics of single pile is analyzed.The research conclusions are as fllows:it is suggested that the minimum length of non enlarged bottom pile should not be less than 2 times the depth of expansion feet;the displacement of pile top in expansive soil cean be redued more efectivele by the long pile with small diameter than by the short pile with large diameter.The method can simulate the displacement and load transfer characteristics of piles at any time under the infuence of seepage,and provides a feasible means for studying the load-bearing behavior of piles in expansive soil.