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Pakbaz M.c., Ahmadi C.,
Volume 1, Issue 2 (December 2003)

This research include, more than 400 erosion tests performed on coarse and fine grain suspension materials. The purpose of tests was to determine erosion characteristics of mixtures of different materials. Samples of the .same constituents in different groups were cured tit two different setting time of // and 16 !tours before they were subjected to the constant hydraulic heads of 20 and 40 cm for ct time period of 30 urinates. The amount of erosion was measured as the weight loss of the samples offer the test. /n general the lower setting tune and the higher hydraulic head for a large group of samples showed higher erosion. For uniform sand samples when the cement content was 60-70 % the percentage of erosion (PE) was below 2. For the mixture of sand-cement, with the clay content below, 20% the percentage of erosion was below 2 and it increased to 15.5 for the clan, content of 58dc. Die addition of bentonite in the soil-cement mixtures in general did not affect the erosion.
Mohammad C. Pakbaz, M. Lorestani,
Volume 3, Issue 2 (June 2005)

The main purpose of this research is evaluation of effect of chemicals on permeability of sand- bentonite mixtures. The coefficients of permeability of sand- bentonite mixtures in water, solutions of sodium and calcium chlorides, sodium hydroxide, acetic acid, methanol and carbon tetrachloride were calculated using parameters obtained in 1- D consolidation test and Terzaghi’s theory. At each void ratio permeability of samples in water is the lowest and that for carbon tetrachloride is the highest. For all fluids the permeability index Ck is decreased as the percentage of sand is increased. The largest Ck belongs to the samples tested in water and the smallest Ck belongs to the samples tested in carbon tetrachloride.
Mahin Roosta R., Sadaghyani M.h., Pak A.,
Volume 3, Issue 3 (September & December 2005)

Existence of discontinuities causes higher deformability and lower strength in rock masses. Thus joints can change the rock mass behaviour due to the applied loads. For this reason properties and orientation of the joint sets have a great effect on the stability of rock slopes. In this paper, after introducing some numerical methods for evaluating the factor of safety for the stability of slopes, stability of jointed rock slopes in the plane strain condition is investigated with the strength reduction technique this method is modified and applied in the multilaminate framework. First of all, stability of one homogeneous rock slope is investigated and compared with the limit equilibrium method. Then stability of a layered rock slope is analyzed with some modifications in the strength reduction technique. Effects of orientation, tensile strength and dilation of layered joint sets on the factor of safety and location of the sliding block are explained.
M.h. Sebt, H. Rajaei, M.m. Pakseresht,
Volume 5, Issue 3 (September 2007)

Project participants are becoming more aware of the high costs and risks associated with delay claims and their litigation. Among delays, weather delay has an important role in projects performed in severe environmental conditions. This research is the extension of delay analysis techniques by approving analysis of weather delays using fuzzy logic. At the presented technique, first using a fuzzy logic model calculated the delay that occurred during the activity execution after weather event then by the selected delay analysis method (Time impact analysis) and using the risk of the contractor during the contract approval together with the effect of previous delay in changing the duration of activities, analyzed weather delays in construction project. A local general contractor and governmental firms involved in a highway construction project practiced by offering their experienced and knowledge in delay analysis procedures to provide data for development and testing of the model specified for rain events. The results indicated that the presented model is in accordance with practical experiences in weather delay duration except in some circumstances that can be divided into the separated parts. It also advances the use of fuzzy logic in delay analysis procedures and becomes it more systematic special for weather delays.
Ali Pak, Zahra Zahmatkesh,
Volume 9, Issue 2 (June 2011)

Geotextiles are one of the most widely used synthetic materials in filtration and drainage applications. Since in real

applications, geotextiles are subjected to various hydraulic gradients and confining stresses, hydraulic behavior of geotextiles

under different circumstances is of great practical importance. In this study filtration and drainage properties of several

nonwoven needle-punched geotextiles with different properties and unit mass per area of 200g/m2, 400g/m2, 500g/m2 and

800g/m2, under various confining stresses and hydraulic gradients, were studied using standard permittivity

and transmissivity equipments. Prepared samples were subjected to hydraulic heads in the range of 10cm to 60cm and

confining stresses up to 1000kPa and their hydraulic behavior was investigated accordingly. In this study the flow regime

through the geotextile fibers and also the anisotropic behavior of geotextile permeability were investigated. The results show

that transmissivity will decrease exponentially with increasing the normal stress until a residual value is reached, and

permittivity and transmissivity coefficients were seen to decrease with increasing the hydraulic gradient. The flow regime has

found to be non-turbulent in all cases.The Geotextile hydraulic behavior is of great usage in the design of landfill covers,

design of embankments and irrigation structures drainage systems, and in the design of protection systems in river


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