软土地区高铁桥梁桩基比例系数合理取值研究

Study on Reasonable Value of Proportional Coefficient of Pile Foundation of High-speed Railway Bridge in Soft Soil Area

在高速铁路桥梁设计中,选取合理的桥梁桩基地基系数的比例系数m值是重要问题。本文依托天津滨海新区铁路项目,进行了单桩和群桩的水平静载试验,对不同水平荷载作用下单桩桩端和群桩承台的水平位移变化规律进行了分析。基于试验结果,对地基土水平抗力系数的比例系数m值进行了计算与拟合,给出了合理的软土地区m值的取值。结果表明:单桩与群桩m值-位移曲线较为接近,随着位移的增加,m值呈现指数型下降趋势。根据拟合结果,对单桩m值进行了推定,建议单桩m值取10MN/m^(4),群桩m值取2.6MN/m^(4)。与规范值相比,单桩m值更大,而群桩m值略小。

In the design of high-speed railway bridges,it is important to select a reasonable value of the proportional coefficient m of the bridge pile foundation coefficient.Therefore,based on the railway project of Tianjin Binhai New Area,the horizontal static load test of single pile and pile group is carried out,and the horizontal displacement variation law of single pile end and pile group cap under different horizontal loads is analyzed.Finally,based on the test results,the proportional coefficient m of the horizontal resis-tance coefficient of foundation soil is calculated and fitted,and the reasonable value of m in soft soil area is given.The results show that the critical load of Z1 single pile is about 360kN,that of Z2 is 220kN,that of Z1 single pile is 500kN and that of Z2 is 300kN.The maximum horizontal load of pile groups is 760kN,and the peak displacement of the top of pile caps is 1.582 mm.The m curves of single pile and pile group are close,and with the increase of displacement,the m decreases exponentially.According to the fitting re-sults,the m of single pile is estimated,and it is suggested that the m of single pile should be 10MN/m4 and the m of pile group should be 2.6MN/m4.Compared with the code,the m of single pile is larger,while the m of pile group is slightly smaller.