The under-consolidated state affects the deformation behavior of deep excavation in soft soil and poses potential risk to the safety of adjacent facilities. However, the deformation model of deep excavation in under-consolidated ground has not been well investigated yet. This study presents a series of numerical analyses on the deformation characteristics of deep excavations in under-consolidated and normally-consolidated ground, each of which is retained by diaphragm walls with rigid struts and a bottom improvement layer. Under-consolidated cases without excavation activities (i.e., simplified as Consolidate cases) were also included for comparison. The modelling results showed that, with the lateral constraint of inner rigid support system, the under-consolidated ground resulted in only a slight increase of lateral wall deformation but a significant increase in ground settlement as compared to normally-consolidated ground. The under-consolidated ground with lower initial average consolidation ratio, thicker surface fill, higher permeability, and longer construction period produced greater wall deformation and ground settlement during excavation. Besides, this study proposed an empirical method to estimate the settlement envelope for deep excavation in under-consolidated ground as the superposition of two parts: settlement induced by excavation activities, and settlement induced by residual consolidation with consideration of average consolidation ratios before and after excavation.

Time and again earthquake-induced damage occurs worldwide as a result of soil liquefaction, especially in loose sands with high groundwater levels. One of the most common types of damage caused by liquefaction results from vertical soil deformations, in other words settlements. This article contributes to the determination of earthquake-related settlements in dry and saturated sands using two-dimensional finite element analyses (2D-FEA) and semi-empirical methods. The comparison of the results obtained from both methods showed that the 2D-FEA give relatively low settlement values compared to the values obtained from the semi-empirical methods. This is mainly explained by the relatively large horizontal earthquake accelerations resulting from the one-dimensional, equivalent-linear dynamic analyses and by the accumulation of earthquake waves at the upper edges of the numerical models.

Ground liquefaction has been reported to occur for shallow earthquakes with a moment magnitude greater than 4.6. The first author of this study has collected many boiled soil samples from various liquefied since 1992. This study is concerned with the grain size distribution, physical and the shear strength properties, permeability/hydraulic conductivity of liquefied granular soils, relative density through laboratory tests and some interrelations are explored. It is shown that every granular geo-material may liquefy if the necessary conditions are satisfied. Large earthquakes may cause even the liquefaction of silty/clayey and/or gravelly soils. Empirical methods purely based on SPT values or its CPT /Vs varieties are not appropriate while the method proposed by Aydan-Kumsar is more appropriate as it can count the most fundamental parameters such as permeability and shear strength of various grounds. If the samples are subjected to pressure under confined state, it is possible to evaluate the characteristics of soils prone to liquefaction at any depth.

Liquefaction is a dangerous and temporary phenomenon whereby water-saturated soil loses all or part of its strength. Undrained conditions associated with cyclic loading increase water pressure in soil pores, thereby reducing effective stress. The aim of this study is, on the one hand, to report on the phenomenon of liquefaction of sand, clay and silt deposits in more or less water-saturated zones in the located at the heart of the central alluvial plain of the Oued Sebou in the mio-plioquaternary Gharb basin and, on the other hand, to study the ability of semi-empirical methods to correctly assess liquefaction potential, while specifying the most appropriate method for the area studied. The study is based on data from experimental results of static penetrometer tests between the Mnasra - Ouelad Salama zone in the Oued Sebou alluvial plain of Morocco's mio-plio-quaternary Gharb basin, made up of sandy, sandy-clay, sandy-silt and silty-sandy formations, which are more sensitive to liquefaction due to their saturation and grain size. We present and discuss the results of Olsen's method, Juang's method and Robertson's method, which are based on the CPT static penetrometer test, as well as looking at the impact of dynamic loading and soil structure on liquefaction probability index values.