海上大直径钢管桩水平向桩土界面参数试桩分析

Analysis on trial pile for horizontal pile-soil interface parameters of large diameter offshore steal-pipe pile

为了研究海上大直径钢管桩水平向承载机理与桩土作用关系,基于海上大直径钢管桩水平向静载试验成果数据,运用API规范建议的p-y曲线方法,结合有限差分解法,对海上大直径钢管桩水平承载特性及桩土界面参数分析计算方法进行研究。结果表明,地基上部土层的性状是影响基桩水平承载性能的主要因素;采用土体参数范围值计算的基桩水平承载性能基本可以反映土体的真实性状。按照API规范给出的p-y曲线模式计算得到的桩身挠度和弯矩与试桩测试数据存在一定的拟合关系,拟合优度在0.891~0.932之间,其中黏性土的拟合优度整体上大于无黏性土,浅层黏性土的拟合优度大于深层黏性土。在0~20 mm水平位移下,桩侧土体处于线弹性状态,桩身挠度与弯矩的计算值均大于测试值,说明此时p-y曲线法低估了土体性能;在大于20 mm的水平位移下,桩侧土体处于非线性状态,桩身挠度与弯矩的计算值均小于测试值,表明此时p-y曲线法高估了土体性能。研究成果可为进一步深入分析海上大直径钢管桩水平向承载性状和桩土的相互作用机理提供参考。

In order to study the relationship between the horizontal bearing mechanism and the pile-soil interaction of large diameter offshore steel-pipe pile,the calculation method for analyzing the horizontal bearing behavior and the pile-soil interface parameters of large diameter offshore steel-pile is study herein with the method of p-y curve recommended by API specification on the basis of the result data from the horizontal dead-load experiment of large diameter offshore steal-pile pile. The result shows that the behavior of the upper soil layer of the foundation is the main factor to influence the horizontal bearing performance of the foundation pile,while the adoption of the horizontal bearing performance of the foundation pile calculated by the values within the range of the soil parameters can basically reflect the real behavior of the soil mass therein. Certain fitting relationships are there between the deflection and bending moment of the pile calculated by the p-y curve specified in API specification and the testing data from the trial pile concerned with the fitting goodness between 0. 891 - 0. 932,in which the fitting goodness of cohesive soil is generally larger than that of cohesionless soil,while the goodness of the shallow cohesive soil is larger than that of the deep cohesive soil. When the horizontal displacement is 0 - 20 mm,the lateral soil mass of the pile is in a linear elastic state and the calculated values of both the deflection and the bending moment of the pile are larger than their testing ones,which indicates that the method of p-y curve underestimates the characteristics of the soil mass. When the horizontal displacement is larger than 20 mm,the lateral soil mass is in a non-linear state and the calculated values of both the deflection and bending moment of the pile are less than their testing ones,which indicates that the method of p-y curve overestimates the characteristics of the soil mass. The study result can provide references for the further deep analysis on the horizontal bearing behavior and pile-soil interaction mechanism.