ENGINEERING GEOLOGICAL STUDIES FOR STABILIZING TELECOMMUNICATION STATION SITE IN THE CITY OF AHVAZ

Engineering geological studies have important role in development of infrastructures in many parts of the world. Selected site for telecommunication station site in elevated part of the city of Ahvaz, in the southwest of Iran experienced instability in the form of cracks in the ground. Engineering geological studies were conducted with the aim of finding the instability factor and stabilizing the site. The geological materials of telecommunication station site were composed of the sequences of sandstone, siltstone and marl covered by marl soils. In situ and laboratory tests were carried out in order to evaluate engineering properties of the materials such as grain size distribution, compressibility, uniaxial and triaxial strengths, swelling potential and slake-durability index . The results obtained from these tests showed that the site’s soil materials which were mainly composed of clay (CL) have intermediate compressibility, low strength, and high swelling potential and the rock materials have relatively medium strength and low slake-durability index. Rock mass rating (RMR) classification showed that rock mass of the site is placed in the class III, the fair rock class. In the next step, rock slope stability analysis was done using SASP software and safety factors were calculated for static and semi static conditions. The calculated safety factors for static and semi static conditions showed that the rock slopes in the site are stable. It was inferred from the studies and conditions of the site that marl soils with high swelling potential are the cause of instability. Chemical stabilization by lime was selected as a way for reduction of swelling potential of the marl soils in the site and enhancement of their engineering properties. Several samples of the marl soils were mixed with different percents of lime and cured in standard times. Different tests such as Atterberg limits, uniaxial compressive strength, swelling, consolidation, and PH tests were applied on the prepared samples to measure their improvement due to addition of lime. It was concluded that chemical stabilization by lime can be used to improve physical and mechanical properties of the marl soils in the site, and reduce swelling potential of them.