Study On Some Of The Engineering Properties Of Soil Found In Chancho Town, Ethiopia

Abstract

Geotechnical investigation of the ground conditions is used for the economical design of the sub -structural elements. It is also necessary to obtain sufficient information on type, characteristics and distributions of a soil and rock underlying at a site of proposed structures for feasibility and economic studies. The present study was made to assess some of the engineering properties of soil found in Chancho town. To achieve the objective, samples were collected from different parts of the town and laboratory tests were done on the collected samples. According to the USCS soil classification system, four soil types were identified: inorganic clays of high plasticity (CH), Inorganic silt of high plasticity (MH), inorganic silt of low plasticity (ML) and inorganic clay of low plasticity (CL). CH is the dominant soil type in the studied area. All the soil samples are composed of different grain size, however fine fractions (silt and clay) are dominant grain size. The different size fraction includes gravel 0 - 1%, sand 6.6 ?�? 30.6%, silt 26.26 ?�? 70.58% and clay 15.42 ?�?54.46%.The Specific Gravity ranges from 2.66 to 2.82. The free swell of the soil is highly variable, from 37.8 (low swelling) to as high as 102% (highly swelling). The liquid limit in percent ranges from 37 to 88, the plastic limit ranges from18.33 to 38.5% and plastic index ranges from 14.4 to 59%. From the compaction test results, the maximum dry density (MDD) and optimum moisture content (OMC), soil of the study area ranges from 1200 to 1480 kg/m3 and 28% to 40% respectively. Unconfined compression test was done for shear strength parameters determination. From this test results the cohesion ranges from 89 to 297kPa, whereas the value of qu ranges from 178-594kPa. Finally one-dimensional consolidation test was done and the test results revealed that the compression index ranging from 0.252- 0.302, coefficient of consolidation ranges from 1.7 * 10-4 to 14.41 * 10-4, coefficient of volume compressibility ranges from 0.06 to 0.246 m2/MN and coefficient of permeability ranging from 0.70 * 10-9 to 31.87 * 10-9 cm/sec. Generally, the soils of the study area are characterized by high plasticity, high compressibility and medium to high swelling potential and they can cause significant damage to light weight structures unless proper design and construction measures are taken.