螺钉桩竖向承载特性数值模拟研究  

Numerical simulation research of vertical bearing capacity of screw pile

作　　者：丁选明[1] 李佳 欧强 DING Xuan-ming;LI Jia;OU Qiang(College of Civil Engineering,Chongqing University,Chongqing 400045,China)

机构地区：[1]重庆大学土木工程学院,重庆400045

出　　处：《地基处理》2022年第5期361-371,共11页Journal of Ground Improvement

基　　金：重庆市自然科学基金创新群体科学基金(cstc2020jcyj-cxttX0003);国家自然科学基金项目(52178312)。

摘　　要：桩基础在我国是应用最为广泛的地基加固方法,而且基桩形式多种多样,其中螺纹类桩相较于其他桩型单桩承载力高、适应性强、适用范围广、环保、经济效益显著,所以目前在国内已经应用较为广泛。预应力螺钉桩是一种新型螺纹类桩型,单桩承载力高。通过PLAXIS有限元软件建立轴对称模型,模拟了螺钉桩单桩承载过程,并对比透明土模型试验,验证了模型的正确性。分析了桩身轴力、桩侧阻力、桩土界面应力以及桩周土体剪应力分布情况,讨论了桩身结构参数的影响。结果表明,螺钉桩桩侧阻力较大,进而显著提高了单桩极限承载力;螺牙下端面桩土界面应力较大,其下侧土体产生了较大的剪应力,发生了剪切变形,发挥了土体抗剪强度;当桩身倾斜角取为0.5°~1°时能提高材料利用率,当平均半径与螺牙间距比值为1.3~2.0时,极限承载力较大,机械咬合作用发挥更充分;螺牙高度占桩顶外径比例提高13%,极限承载力提高了23%;螺钉桩螺牙厚度对其单桩承载力的影响较小。Pile foundation is the most widely used method of foundation reinforcement in our country,and there are many types of foundation piles.Compared with other type piles,threaded piles have been widely used in China for higher bearing capacity,strong adaptability,wide application range,environmental protection and significant economic benefits.The screw pile is a new type of threaded pile with high bearing capacity.The axisymmetric model was established by PLAXIS finite element software.The bearing process of the screw pile was simulated,and the correctness of the model was verified by comparing with the transparent soil model test.The axial force,the lateral resistance of the pile,the stress of the pile-soil interface,the distribution of the shear stress of the soil around the pile were obtained.The law of influence of the pile structure parameters was discussed.The results show that the lateral resistance of the screw pile is relatively large,which significantly increases its ultimate bearing capacity.The interface stress between the pile and soil at the lower surface of the screw thread is relatively large,and the large shear stress is generated in the soil on the lower side,resulting in shear deformation and exerting the shear strength of the soil.When the inclination angle of the pile is taken as 0.5°-1°,the material utilization rate can be improved.When the ratio of the average pile radius to the thread pitch is 1.3-2.0,the ultimate bearing capacity is larger and the mechanical occlusal effect is more improved.When the proportion of the thread height to the outer diameter of the pile top is increased by 13%,the ultimate bearing capacity is increased by 23%.The thickness of the thread has little effect on the bearing capacity of the single pile.

关 键 词：螺钉桩 侧摩擦力 荷载-沉降曲线 竖向承载 数值模拟 

分 类 号：TU473[建筑科学—结构工程]