Effects of lateral cyclic loading on the surrounding soil stiffness of a modelled single pile

Abstract

This study focuses on the effects of lateral cyclic loading by Displacement-controlled amplitudeon the surrounding soil stiffness of a modelled single pile in sandy soil. This model demonstrates the behaviour of a single pile within Integral bridge which receives the cyclic loading from thedisplacement amplitude change from temperature. Because of the change of temperature, the bridges expand and shrink themselves in term of distance and time. Then, this study occurs. By the behaviours of the piles is evaluated through the bending moment distribution, lateral displacement, shear force and soil resistance (subgrade reaction) along with the pile. For determining the soil stiffness, the code is written in MATLAB® in term of the numerical analysis method. The change of soil stiffness from the number of cyclic loading is the main study in different soil levels and the peak applied loads. According to this study, the initial soil stiffness (Nc=1) increases on the deep of soil level because of strain-level effect. After that, the soil stiffness rapidly increases in term of plastic material, then, it keeps constant in term of elastic material, On the other hands, at soil-level around soil surface, the soil stiffness increases with the number of cyclic loading. This effect could be called “Ratcheting Effect”, i.e. when the sandy soil active fails, the increasing lateral pressure is needed to move back itself. When the lateral pressure increases, the soil stress increases, therefore, the soil modulus and stiffness also increase. However, the soil stiffness has a significant relationship with the soil level and the displacement amplitude.