短芯PHC管桩水泥土根植桩竖向承载力数值模拟

Numerical Simulation of Vertical Bearing Capacity of Cemented-Soil Pile Rooted With Short-Core PHC Pipe Pile

为研究短芯预应力高强度混凝土(PHC)管桩水泥土根植桩的竖向荷载传递规律,结合现场案例展开数值模拟;分析各级荷载下管桩及水泥土桩身应力与侧壁摩阻力分布特征,研究根植桩的受荷规律和承载力影响因素.数值模拟结果表明:在管桩长度范围内,水泥土对管桩侧阻力的发挥做出了贡献,在管桩桩端处,荷载由管桩向水泥土传递,使得此处水泥土应力应变急剧增加;管桩桩端附近水泥土的侧向变形突增,增加了管桩-水泥土界面的摩擦强度,明显提高了管桩的侧摩阻力;管桩桩端附近水泥土塑性变形集中,是根植桩的一个薄弱环节.此外,水泥土粘聚力的增加能较为显著提高根植桩承载力,但水泥土的弹性模量及摩擦角对根植桩承载性能影响小.为充分发挥根植桩承载力,在进行设计时,宜使水泥土的粘聚力为250 kPa、摩擦角为40°、弹性模量为400 MPa.

In order to study the vertical load transfer of the cemented-soil pile rooted with short-core pre-stressed high-strength concrete(PHC)pipe pile,numerical simulation was carried out in combination with field case.The distribution characteristics of axial stress and lateral friction resistance of the pipe pile and cemented soil under various load steps were analyzed.The load-bearing and influencing factors of bearing capacity of rooted pile was studied.The numerical simulation results show that:In the length range of pipe pile,cemented soil contributes to the lateral resistance of pipe pile.At the end of pipe pile,the load is transferred rapidly from the pipe pile to cemented soil,resulting in a sharp increase in the stress and strain of cemented soil here.The lateral deformation of cemented soil near the end of pipe pile increases sharply,which increases the friction strength of the interface between pipe pile and cemented soil,and also increases obviously the lateral friction resistance of pipe pile.Plastic deformation is concentrated at the cemented soil near the end of pipe pile,resulting in a weak part of the rooted pile.The increase of cohesion of cemented soilcan significantly improves the bearing capacity of the rooted pile.However,the elastic modulus and friction angle of cemented soil have little effect on the bearing capacity of the rooted pile.In order to fully develop the bearing capacity of the rooted pile,the cohesive force of cemented soil 250 kPa,the friction angle 40°and the elastic modulus 400 MPa are suggested for design.