A. Johari

Reliability analysis of static liquefaction of loose sand using the random finite element method

Purpose – Liquefaction of soils is defined as significant reduction in shear strength and stiffness due to increase in pore water pressure. This phenomenon can occur in static (monotonic) or dynamic loading patterns. However, in each pattern, the inherent variability of the soil parameters indicates that this problem is of a probabilistic nature rather than being deterministic. The purpose of this paper is to present a method, based on random finite element method, for reliability assessment of static liquefaction of saturated loose sand under monotonic loading. Design/methodology/approach – The random finite element analysis is used for reliability assessment of static liquefaction of saturated loose sand under monotonic loading. The soil behavior is modeled by an elasto-plastic effective stress constitutive model. Independent soil parameters including saturated unit weight, peak friction angle and initial plastic shear modulus are selected as stochastic parameters which are modeled using a truncated nor...

Reliability Assessment of Unsaturated Soil Shear Strength Using the Jointly Distributed Random Variables Method

Shear strength of unsaturated soil is a very important topic in unsaturated soil mechanics. Shear strength is dependent on a number of variables and is highly amenable to probabilistic treatment. Probabilistic analysis of shear strength is used as an effective tool to evaluate uncertainty so prevalent in soil variables. In this research the jointly distributed random variables method is used for probabilistic analysis and reliability assessment of Fredlund’s shear strength equation. The selected stochastic parameters are effective angle of shearing resistance for saturated soil (’, angle of shearing resistance with respect to matric suction (b and effective cohesion of saturated soil (c’), which are modeled using truncated normal probability distribution functions. The stress variables i.e., net normal stress and matric suction on the plane of failure are regarded as deterministic parameters. The resultant probability density functions are compared with the Monte Carlo and Point Estimated methods. Comparison of the results indicates superior performance of the proposed approach for assessment of reliability of the shear strength model for unsaturated soils.