الفهرس 
CHAPTER ( 1 ) : REVIEW OF LITERATUREOnly 14 pages are availabe for public view
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Abstract
Soft clay regions are widely spread throughout the Nile Valley and the Delta.
Such regions are mostly of thick thickness , low carrying capacities, of high settlement and long time consuming in reaching its final consolidation settlement . Therefore , such regions are considered as some sort of obstacle that faces the constructional process . This research aims at investigating the effect of reinforcing soft clay regions with gypsum piles on constructional properties of such regions . Laboratory work conducted in this research is branched out into two main parts .
The first part of laboratory work covers the case of a thin clay layer reinforced with end bearing piles. The unconfined carrying capacity of gypsum piles placed in soil ,environment of varying consistencies were estimated . Subsequent photographs of moisture advance through the gypsum pile were taken to determine rate of moisture movement and to indicate moisture providability of surrounding soil. A drained triaxial test was conducted to estimate the change in friction angie and cohesion of unpiled and piled samples.
The second part covers the case of relatively thick soft clay layer that gypsum piles can not be extended to its sublaying firm layer . To cover this case a consolidation experiment in the Rowe consolidation cell has been conducted on both unpiled and piled samples. In this experiment piling length was taken as an independent variable ( 0.25 H , 0.5H, 0.75H and H , where H is height of the sample ). Dependent variables are time required for reading UlOO , consolidation settlement , void ratio and coefficient of volume change , coefficient of consolidation and modulus of elasticity. A scanning microscope and X - Ray diffraction analyses were conducted to estimate whether a physical and/or chemical alteration will occur across the contact surface. A permeability test was conducted on a clay sample and on a gypsum cack hardened in the same tested soil environment . It was found that: Moisture movement through the gypsum
pile is inversely proportional to soil’s cohesion and directly proportional to water content of soil environment . This research , also , proved that unconfined carrying capacity of gypsum pile increases with the decrease of soil’s cohesion. The carrying capacity reaches a maximum value with the consistency that provides it with an amount of moisture nearly equaling that required for obtaining standard gypsum mortar. Gypsum piling considerably increases drained angle of friction and cohesion of soft clay. In general, time required for reaching UlOO is considerably reduced in gypsum piled samples than in unpiled ones . It is inversely proportional to piling length at relatively low applied stress. However, piling length has nearly no effect at relatively high applied pressures. Gypsum piling considerably reduces consolidation settlement, and increases coefficient of consolidation.
A chemical reaction was indicated through the contact surface of the gypsum pile and the sUITounc4ng clay. This was evident through observing the increase in sulpher ratio in the sample taken from just beside the gypsum pile compared to its ratio in the sample that was taken far from the affection of the pile.
The coefficient of vertical and horizontal permeability of a hardened gypsum cake were observed to be 1.6, as high as those of the soil environment in which the cake has hardened. Inspite of this relatively small difference, piled samples consumed a considerably short time to reach U 100 compared to unpiled samples.