Experimental Study on Pile-Soil Interaction Response in Saturated Sand under Long-Term Horizontal Cyclic Loading

Lei Xing,Li Wang,Duoyin Wang,Lunliang Duan,Meiling Fan,Shangtong Yang

doi:10.1155/2021/6627161

Abstract

To explore the pile-soil interaction response in saturated sand under long-term horizontal cyclic loading, a series of indoor 1 g model tests were carried out with self-made loading equipment. In this paper, the self-made loading system and test program are introduced firstly. Then, the long-term horizontal cyclic loading-induced pile top cumulative displacement, the rotation angle, the mono-pile horizontal cyclic stiffness, the cyclic p-y curve, the pore water pressure, the soil settlement, and cracks around mono-pile are fully studied. Based on the experimental results, the pile-soil interaction response shows a two-stage characteristic with the change in cycle (N), and the short-term effects of horizontal cyclic loading are greater than the long-term effects. In the first 1000 cycles, the cumulative displacement of pile top, the rotation angle of mono-pile, and the pore water pressure could reach more than 90% of the final value. In addition, the cyclic p-y curve obtained by the test is generally smaller than the p-y curve calculated from the API specification, and the soil near the mono-pile will settle with annular cracks under the cyclic loading.

Highlights

In the past decade, with the continuous development of science and technology and the sustainable development needs of clean and environment-friendly energy, offshore wind power has entered a period of rapid development [1,2,3,4,5]
A host of studies have shown that when the rotation angle of pile shaft exceeds 0.5°, the offshore wind turbine will not work normally [8]. erefore, it is of great significance to study the long-term loading response of offshore wind power foundation under horizontal cyclic loading for the design and stability evaluation of offshore wind power foundation [9]
Study of variation rules of pore water pressure within the pile-soil interface under horizontal cyclic loading is relatively less, and the loading cycles of tests of the existing researches are mostly concentrated within 1000 cycles. erefore, the small-scale model test of single pile under horizontal cyclic loading was carried out in this paper using the self-made indoor model test cyclic loading system, and the number of cyclic loading was over 5 × 103 cycles to study the long-term response of mono-pile under horizontal cyclic loading

Summary

Introduction

With the continuous development of science and technology and the sustainable development needs of clean and environment-friendly energy, offshore wind power has entered a period of rapid development [1,2,3,4,5]. Little et al, Long et al, and Lin et al proposed empirical formulas for cumulative deformation of single pile foundation in sand under horizontal cyclic loading through field tests [10,11,12]. In terms of numerical simulation, Achmus et al and Depina et al proposed an improved stiffness attenuation model to calculate the cumulative deformation of single pile under cyclic loading through secondary development, but this model ignored the hysteresis effect of soil under cyclic loading [25, 26]. Erefore, the small-scale model test of single pile under horizontal cyclic loading was carried out in this paper using the self-made indoor model test cyclic loading system, and the number of cyclic loading was over 5 × 103 cycles to study the long-term response of mono-pile under horizontal cyclic loading.

Model Test

D 2 D 3 D

Conclusions