软土地区不同预制桩型承载特性现场试验与模型验证

Field Test and Model Validation of Load-Bearing Characteristics of Different Types of Prefabricated Piles in Soft Soil Areas

摘要:

为深入探究预应力高强混凝土(PHC)管桩及预应力混凝土实心方桩(YZH)在软土地区的竖向抗压承载特性,依托于上海某工程,对6根PHC管桩和2根YZH桩进行单桩竖向抗压静载试验,对比分析两种预制桩的荷载-位移特性,评估指数函数模型在预测单桩竖向抗压极限承载力方面的适用性,并对指数函数模型进行修正。结果表明,该试验场地的2种桩型均发生破坏,荷载-沉降曲线均呈陡降型,桩顶荷载水平介于4 725~6 000 kN之间时试桩发生破坏,残余沉降占比均在87%以上;采用修正指数模型预测试桩的单桩极限承载力更为精准,吻合度更高,且预测曲线变化趋势在塑性变形阶段具有较高的预测精度。

Abstract:

In order to deeply explore the vertical compressive bearing characteristics of prestressed high-strength concrete (PHC) pipe piles and prestressed concrete square (YZH) piles in soft soil areas, a single-pile vertical compressive static load test was carried out on 6 PHC pipe piles and 2 YZH piles based on a project in Shanghai, and the load-displacement characteristics of the two types of prefabricated piles were compared and analyzed. The applicability of the exponential function model in predicting the vertical ultimate compressive capacity of single piles was evaluated, and the exponential function model was modified. The results showed that both pile types at the test site failed, and the Q-s curves showed a steep drop. The pile top load level was between 4 725 kN and 6 000 kN, and the resi-dual settlement accounted for more than 87%. Using the modified exponential function model to predict the ultimate bearing capacity of single piles is more accurate and exhibits high consistency, and the prediction curve trend has higher prediction accuracy in the plastic deformation stage.