determination of volume change of unsaturated soils during loading and suction change is one of the most important difficulties in testing unsaturated specimens. it is revealed from literature review that various attempts have been made to invent an apparatus that can be used in testing on unsaturated soil specimens, simply and accurately. in this research, details of design and manufacture of ...

An understanding of gas transport in unsaturated media is important for evaluation of soil aeration or movement of O 2 from the atmosphere to the soil. Soil aeration is critical for plant root growth because roots generally cannot get enough O 2 from leaves. Evaluation of gas movement is also important for estimating transport of volatile and semivolatile organic compounds from contaminated sit...

A two-dimensional finite element model is proposed to simulate transient seepage for complex groundwater flow systems. The complete soil system is treated as a continuum encompassing flow in both saturated and unsaturated zones. In the unsaturated zone, the air phase is assumed to be continuous and open to atmospheric pressure. The coefficient of permeability of the unsaturated soil is assumed ...

On military training ranges, low-order, incomplete detonations deposit RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) into surface soils. In this study, we evaluated RDX biodegradation in surface soils obtained from a military training range in Alaska. Two factors were compared: (i) soil water potential during the incubations; and (ii) the use of acetonitrile (ACN) as an RDX carrier to spike sam...

Soil contamination represents an environmental issue which has become extremely important in the last decades due to the diffusion of industrial activities. Accidents during transport of dangerous materials and fuels may cause severe pollution. The present paper describes the criteria of the actions which were operated to remediate the potential risk and observed negative effects on groundwater...

 In pavement design, the CBR and direct shear tests are two very common laboratory investigations for predicting the strength of a subgrade layer. The relationship between the CBR and water content has been commonly presented in analyses, with the result of the direct shear being expressed from the aspect of effective cohesion and the internal friction angle. Even though most natural soil is in...

Preferential flow in the unsaturated soil is an important and common phenomenon, which is difficult to be characterized. The objective of this paper is to evaluate the Active Region Model (ARM), which incorporated the fractal flow patterns into the continuum approach, has been developed to characterize preferential water flow in the unsaturated zone. Experiments were conducted to measure water ...

A simple method for the installation of groundwater lysimeters in peat soils was developed which reduces both time and financial effort significantly. The method was applied on several sites in the Rhinluch, a fen peat land 60 km northwest of Berlin, Germany. Over a two-year period, upward capillary flow and evapotranspiration rates under grassland with different groundwater levels were measure...

A numerical solution for heave prediction is developed within the context theories for both saturated and unsaturated soil behaviors. Basically, lowering the potential level of compressing on a saturated layer will cause heaving due to water absorption. This water absorption is in an opposite way, similar to water dissipation as what happens during unloading in consolidation process. However, i...

This paper presents an overview of constitutive modelling of unsaturated soils and the numerical algorithms for solving the associated boundary value problems. It first discusses alternative stress and strain variables that can be used in constitutive models for unsaturated soils. The paper then discusses the key issues in unsaturated soil modelling and how these issues can be incorporated into...