Rainfall-induced differential settlements of foundations on heterogeneous unsaturated soils

Abstract

This study stochastically investigates the rainfall-induced differential settlement of a centrally loaded, rigid strip foundation on an unsaturated soil with spatially varying values of either preconsolidation stress or porosity. The differential settlement (between the two foundation ends) is calculated at various times during rainfall by way of a coupled, hydro-mechanical, finite-element analysis. The Barcelona basic model describes the mechanical behaviour of the soil, and the van Genuchten relationships describe water retention and permeability. The variability of soil properties is modelled by means of random fields with spatial correlation in the framework of a Monte Carlo simulation. The study demonstrates that the occurrence of rainfall-induced differential settlements can be consistently analysed using concepts of unsaturated soil mechanics and random field theory. Results show that differential settlements can be vastly underpredicted (or even completely missed) if random heterogeneity and partial saturation are not simultaneously considered. The variation of differential settlements and their statistics during the rainfall depend on the magnitude of the applied load and the statistics of soil variability. Moreover, the transient phase of infiltration and a spatial correlation length equal to the width of the foundation pose the highest risk of differential settlement.

Coupled hydromechanical analysis of an underground compressed air energy storage facility in sandstone

“…Two plausible scenarios corresponding to short and long correlation lengths were explored. To generate random porosity fields, the procedure proposed by Le et al (2011Le et al ( , 2013) was adopted. This method combines local average subdivisions (Fenton & Griffiths, 2008) with a Markovian correlation function.…”

Consolidation in spatially random unsaturated soils based on coupled flow‐deformation simulation

“…The cross‐correlated random fields can be discretized using the extended matrix decomposition technique . A simple approach is to assume that the random soil parameters are related with the same soil property such as soil density .…”

“…Very limited research has been carried out on the effects of the spatial variability of deformable unsaturated soils. Recently, Le et al investigated rainfall‐induced differential settlement of a strip foundation on an unsaturated soil with spatially varying values of either preconsolidation stress or porosity. They adopted the elasto‐plasic Barcelona Basic Model (BBM) for representing the mechanical behavior of unsaturated soils and used a fully coupled hydro‐mechanical code for performing the numerical solutions.…”

Probabilistic Assessment of Randomly Heterogeneous Soil Slopes

“…Zhang (1999), Tartakovsky et al (2003), Yang et al (2004), Lu and Zhang (2007), Li et al (2009), Mousavi Nezhad et al (2011, Cho (2012), Le et al (2012), and Meftah et al (2012) among others, analyzed unsaturated flow in heterogeneous soils with spatially distributed uncertain hydraulic parameters. Le et al (2013) investigated rainfall-induced differential settlement of a strip foundation on an unsaturated soil with spatially varying values of either preconsolidation stress or porosity. Srivastava et al (2010), Santoso et al (2011), and Zhu et al (2013) simulated permeability as a spatially correlated lognormally distributed random variable and studied its influence on water flow and slope stability.…”