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Abstract In this study, the relationship between Index Property and Swelling characteristic of Expansive soil of Bahir Dar is examined. The test results showed that the Specific Gravity ranges from 2.55 to 2.81. The Index Property Test showed that Plasticity Index ranges from 44.5 to 76.42%. The clay content of the soil is from 55.4 to 87%. Free Swell tests conducted on the collected samples showed a range from 78 to 215%. According to the Unified Soil Classification System. The soil is categorized as Fat or Organic Clay with a potential of expansion. AASHTO Classification System also shows that the soil is Plastic Clay with high volume change capacity. The dry density of the soil, which samples were taken from, ranges between 1.04 and 1.39 gm/cc. Another test conducted using one-dimensional consolidometer showed that the Swelling Pressure of the area ranges between 75.95 and 547.52 kpa. Relationship observed between Index Property and swelling characteristic of the area showed that with the increment of clay content in the soil the Plasticity Index, the Cation Exchange Capacity and the ω max 24 is increased. The increment of the Plasticity Index is in turn reflected in increasing the swelling pressure of the soil. Dry Density of the soil also increases the swelling pressure. On the other hand Natural Moisture content affects the swelling pressure negatively. A single Index Property is not a reliable means of predicting the swelling pressure of the soil while a better estimation is observed when different Index Properties are involved in prediction the swelling pressure The relation of (ω max 24 /ω)∗γ d or (ω max 24 /ω) with swelling pressure showed a better indicative value than the PI for the study area. -------------------------------- 92 8
1. Introduction 1.1 General Bahir Dar is founded in the 14 th century along with the establishment of the Kidane Mihret church near lake Tana. The place was known as Bahir Dar Kidane Mihret until the 17 th century. After the establishment of the St. George church however, the name was changed to Bahir Dar Giorgis which was in use until the advent of the Italians in the 1930s. The Italians then abolished the administration of the area by the church and the town started to be simply known as Bahir Dar [15]. According to NUPI 1996, the geographical location of Bahir Dar is at 11 0 38’ North latitude and 37 0 10’ East longitudes. The town is located at about 565 km North West of Addis Ababa and it lies in an area characterized by a general flat topography in the southern shore of lake Tana. Since Bahir Dar is an important center of Amhara National Regional state, development activities are flourishing and the town is expanding in all directions (except to lake Tana). According to the recent demarcation of the town, areas previously considered as rural ‘Kebeles’ are now recognized as part of the town which significantly increases the total area of the boundary to 15,455 hectare [ Fig. 1,2 ]. Previous rural kebeles demarcated recently as town are: Zenzelma Wereb Dishet Abaraj Weramit Sebatamit 4,200 ha 1,780 ha 2,250 ha 4,200 ha 525 ha 1
Page 1 and 2: ADDIS ABABA UNIVERSITY SCHOOL OF GR
Page 3 and 4: DECLARATION I, the undersigned, dec
Page 5 and 6: List of Tables Page Table 1: Mean M
Page 7: List of Symbols A c = Activity ω l
Page 11 and 12: Recent Map of Bahir Dar Area Accord
Page 13 and 14: 1.4 Lithologic Units and Soils Resi
Page 15 and 16: 2. Literature Review 2.1 General Pl
Page 17 and 18: Soil water chemistry Soil water has
Page 19 and 20: 2.3.2 Direct Measurement This type
Page 21 and 22: 3. Identification of Soil in the St
Page 23 and 24: Location Color Depth Northing Easti
Page 25 and 26: Table 4. Atterberg and Shrinkage Li
Page 27 and 28: Swell Potential Plasticity Index Lo
Page 29 and 30: Location Depth Gs Tp4-1 1.5 2.78 Tp
Page 31 and 32: Location Depth Sand (%) Silt(%) Cla
Page 33 and 34: Location Depth ω 24 (%) Kebele 9 2
Page 35 and 36: Table 9 : Free Swell Test Results o
Page 37 and 38: For the study area the CEC is deter
Page 39 and 40: 4. Soil Classification Soil classif
Page 41 and 42: 100 Plastic Index (%) 80 60 40 20 0
Page 43 and 44: I ) Clay Content and Plasticity Ind
Page 45 and 46: 5 Determination of Swelling Pressur
Page 47 and 48: 5.1 Swelling Pressure and Index Pro
Page 49 and 50: 3 Log Sp (Kpa) 2 1 1 1.2 1.4 1.6 Dr
Page 51 and 52: 600.00 Swelling pressure (Kpa) 500.
Page 53 and 54: 6.1 Models Developed by Various Res
Page 55 and 56: Table 13. Comparison of Previously
Page 57 and 58: Using the above new equations the s
Page 59 and 60:
Equation 2 800 Calculated Value (Kp
Page 61 and 62:
Equation 6 Calculated Value (Kpa) 9
Page 63 and 64:
Conclusion and Recommendation 1. Th
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