The unexpected softening of the undrained shear strength of organic and silty clays in Rhine delta: a conceptual study: Determining the Undrained Shear Strength of soft Dutch soils using conventional laboratory equipment

The current Dutch norms for the macro-stability of ood protection embankments and more specifically the determination of SHANSEP parameters has been subject of debate since its implementation in 2017. The main concerns arise from the apparent over-conservative nature of the guidelines and the apparent underestimation of shear strength of organic...

Monitoring Backward Erosion Piping with Self-Potential Geophysics

Backward erosion piping is a dike failure mechanism. It is the internal erosion process by which sand is eroded away from underneath a dike or levee by seepage flow. This erosion process progresses in the direction opposite to the direction of seepage flow and forms a small pipe directly beneath the dike. As erosion continues, this process can...

A parametric study on the bounding surface SANICALY model for cyclic behaviour of Kaolin clay

Cyclic loading tends to affect the strength and stiffness parameters of soils, degrade its structure and results in accumulation of the excess pore water pressure. Such behaviour often leads to premature failure of the soils. Over the past few decades, geotechnical research community has developed numerous constitutive models to predict the...

Preloading of a lumpy clay fill: A study into the closure of the interlump voids of a mechanically dredged stiff clay fill

Mechanical dredging of a stiff clay results in clay lumps. Those clay lumps can be reused for the construction of land reclamation projects, and hereby economic and environmental value is generated. Placement of the clay lumps<br/>in water result in a matrix of clay lumps and an interlump void space. The collapse of the interlump void space will...

Advances in Modelling the Deviatoric Response of Peat

The term peat is commonly used to describe organic soils, composed of fragmented plant remains and fibers. Despite the extensive research on the behaviour of peat during the last 50 years, the vast majority of the attention was devoted to the volumetric behaviour. Only few attempts are reported to model the deviatoric behavior of peat, which is...

Denitrification-based pretreatment for the compaction of silty sands

Recent developments in bio-based soil improvement techniques include the use of the bacterially mediated process of denitrification to alter engineering properties of soils. Pham (2017) used the denitrification process to stimulate the production of gas and precipitation of calcium carbonate as a soil improvement method. The ability to...

Contributions of a time-dependent 3D coupled analysis of a system of relief wells

The maintenance and improvement of river embankments plays a crucial role in granting the safety and ensuring the quality of life of the inhabitants of the Netherlands. While the threat posed by storm surges has been greatly reduced since the implementation of the Deltaworks, riverine areas in the west of the country are characterised by the...

Influence of the initial soil stress state on the cone factor: Reducing the uncertainties in the design of dikes on peat and clay

The uncertainties in undrained macro-stability analysis of dikes lead to overdimensioned and inefficient designs. The undrained shear strength (su¬), which describes the strength of clay and peat layers, is important information for the macro-stability analysis of a dike. The cone factor (Nc) gives a linear correlation between undrained shear...

Enhanced Bounding Surface Modeling of Sand Behaviour under Multiple Loading Cycles

Cyclic behaviour of soil has stimulated researchers for several decades to develop constitutive models that will be able make accurate predictions of soil behaviour and at the same time they will be simple to use. Constitutive models are considered to be more valid compared to empirical models, because they comprise by equations that have actual...

Numerical simulation of the coupled hydro-mechanical response of the Leendert de Boerspolder dyke

This study was conducted in the framework of the Leendert de Boerspolder stress test. It focuses on the investigation the performance of the available constitutive models in describing the coupled hydro-mechanical response of peats and organic clays as observed during the stress test. The soil models that are considered are the Mohr-Coulomb...

Compaction of silty sands through biogenic gas desaturation pretreatment

This thesis entitled “Compaction of Silty Sands through Biogenic Gas Desaturation Pretreatment” investigates a method to improve compactibility of an initially fully saturated soil body bringing it to a saturation corresponding to the optimum water content of the targeted soil layer. The process comprises<br/>two stages: a reaction phase to...

Towards Improved Design of Rock Reinforcement Systems for Underground Excavations Subjected to Strain Bursting

This thesis report presents a concept methodology to quantify the energy release associated with strain bursting in underground excavations based on the size of the failed zone and the elastic strain energy stored in the rock mass prior to failure. A strain burst implies potential harm to people and machinery and may lead to economic loss. An...

Finite element analysis of dyke in the concept of Eurocode 7: Additional thesis project

State of the art geotechnical engineering and project designare nowadays rigidly connected to the mindful adaption of the Eurocode. However, questions can be raised on the critical selection of the characteristic values for parameters such as the soil compressibility and permeability. The experiment conducted at Leendert de Boerspolder, where a...