Geotechnical Properties and Slopes Stability for Banks Soils in South Part of Al-Hilla River at Meandering Areas, Babylon Governorate / Central of Iraq

Abstract

    The south part of the Babylon Governorate, located on the Hilla River, suffers from collapse and erosion of its banks, as well as the increase in sedimentation in the river, which reduces the river flow efficiency; due to the effect of the velocity river flow, which works on eroding one side of the river and sedimentation on the other side, forming meanders in the river. After the reconnaissance visit determine the meandering sites. A detailed study of the area was carried out by drilling (6) test boreholes representing three areas (Al-Wazeer, Al-Ibraheemia, and Al- Hashemia), two wells on both sides of the meander and at a depth of (10 m), for each borehole to observe the effect of the river flow velocity on the stability of slopes and to know the variation in soil properties, its bearing capacity and the consolidation on both sides of the river, and thus its effect on the engineering construction. Soil samples have been taken to carry out physical tests including: (moisture content test, specific gravity test, Atterberg limits tests, sieve analysis, and hydrometer tests), also engineering tests were done which included (permeability test, unconfined & triaxial compressive strength test, direct shear test, consolidation test, and bearing capacity), soil chemical tests that done (pH, total soluble salt, sulfate test, chloride test, gypsum test, and organic matter test). A study was also conducted for the stability of the bank slopes for the three stations, where the cross-section was monitored by the M9 device, as well as the height of the banks from both sides by the (level) device, Using Geo-Studio 2021 program with soil properties and by using (Bishop method) the safety factor was extracted for the two stations for erosion-prone areas. The highest result of the safety factor was in Al-Ibraheemia Station (2.85), then the banks of Al-Wazeer Station, with a value of (2.3), and the lowest value of Al-Hashemia Station, which amounted to (1.84). Under natural conditions, the average river flow level reaches it in a year is (27.15 m) above sea level. Where all the stations were (safe) unless the water level increased or decreased. Also, the research reached a determination of the allowable bearing capacity that soil of the banks reaches it before the landslide.