既有竖向荷载对承台桩水平承载特性影响的PIV试验研究

为研究既有竖向荷载下承台桩的水平承载特性，进行了2组PIV模型试验，分析了不同竖向荷载对承台桩的水平位移量、桩身弯矩及桩周土体位移场的影响规律，研究了竖向荷载对承台桩下桩土作用的影响机理。试验结果表明：在同一水平荷载下，桩顶既有竖向荷载有利于减小桩身水平位移，削弱水平荷载引起的桩身弯矩；在水平加载过程中，桩土作用的主要区域为桩周土体的中上部区域，桩顶竖向荷载的施加会调动桩侧土体，形成更大的土体扰动区；竖向荷载引起的土体密实化效应会降低桩身的水平位移和弯矩，提高承台桩的水平承载力；同时这一密实现象也降低了桩侧土体的隆起量与塌陷面积。

PIV Experimental Study of Existing Vertical Load on Horizontal Bearing Capacity of Pile with Cap

To study the horizontal bearing capacity of pile with cap under the existing vertical load, two groups of PIV model test were carried out. The effects of different vertical loads on the horizontal displacement, bending moment of pile and soil displacement field around pile are analyzed. The influential mechanism of vertical load on pile-soil interaction under pile with cap is studied. The results show that the existing vertical load decreases the horizontal displacement, weakens the bending moment of pile under the same horizontal load. In the process of horizontal loading, the main region of pile-soil action is the middle and upper region of the soil around the pile. The application of the vertical load on the pile top will mobilize the soil around the pile, form a larger soil disturbance area. The soil densification effect caused by vertical load will reduce the horizontal displacement and bending moment of pile and increase the horizontal bearing capacity of cap pile. Meanwhile, this densification phenomenon also reduces the uplift and collapse area of pile side soil.