Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : Unsaturated soil


Numerical Modeling of Pore Water Pressure Development in Mosul Dam

Suhail A. A. Khattab; Amina A. Khalil

Engineering and Technology Journal, 2013, Volume 31, Issue 4, Pages 618-631

A finite element method is useful tools to be applicable in many geotechnical engineering topics. In this paper the pore water pressure development within the clay core of MOSUL earth dam were investigate considering the saturated/unsaturated conditions using GEO-SLOP software. Three selected sections through the dam were chosen for the analysis ( in the middle, right, and left sides of the dam to cover the dam body). The investigation of the dam body response to the earthquakes with many values of the maximum horizontal acceleration was done. Normal, maximum, and minimum operation water levels with possibility of rapid drawdown of water level during (8,21,30) days were also consider. Transient and steady state analysis of pore water pressure was performed, finally the results were compared with the actual field data.
Results indicated that, the maximum pore water pressure was occurred for the nodes in the upstream near of the core base at the time during and after the end of earthquake shaking. The results of the study also presented a positive pore water pressure development in the lower part of the core when the water was at maximum, normal, and minimum operation levels, with negative values near the crest of the dam. high pore water pressure was record through sec6 and sec4, for the rapid drawdown of water level at time 8 days. Finally, nearly identical pore water pressure results are obtained from the numerical analysis and the recorded field piezometers readings data.

Consolidation Characteristics of Unsaturated Soil

Firas J. Kadhim; Mohammed Y. Fattah

Engineering and Technology Journal, 2009, Volume 27, Issue 10, Pages 2027-2046

The most common three-phase problem in porous media is the flow of air and water. This is for example found in the unsaturated zone, where water infiltrates through partly saturated pores to the groundwater. Liquid flow in the unsaturated zone is controlled by a combination of gravitational, capillary, and viscous forces. The mechanical behaviour of partially saturated soils can be very different from that of fully saturated soils. It has long been established that for such soils, changes in suction do not have the same effect as changes in the applied stresses, and consequently the effective stress principle is not applicable. Conventional constitutive models, which are based on this principle, are therefore of limited use when analyzing
geotechnical problems that involve the presence of partially saturated soil zones. In this paper, Al-Mdaina trial embankment was the problem analysed. The finite element programs SIGMA/W and SEEP/W were used, and eight noded isoparametric quadrilateral elements were used for modelling both the soil skeleton and pore water pressure. Parametric study was carried out and different parameters were changed to find their effects on the behaviour of partially saturated soil. The
parameters include the modulus of elasticity and permeability of the soil. It was concluded that the effect of modulus of elasticity on the behaviour of unsaturated soil is apparent at early stages of consolidation and diminishes when the time proceeds. When the clay layer consists of soft clay (Esoil <10000 kN/m2), the effect of unsaturated soil is apparent, while the effect of the modulus of elasticity diminishes when the soil is stiff.