Geotechnical assessment of road failure and slope monitoring along Nsukka-Adoru-Idah highway, Southeastern Nigeria

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• 作者：Raphael Iweanya Maduka ; Ogbonnaya Igwe…
• 关键词：Subgrades ; Base course ; California bearing ratio ; Stabilization ; Highway ; Landslide
• 刊名：Environmental Monitoring and Assessment
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：189
• 期：1
• 全文大小：
• 刊物类别：Earth and Environmental Science
• 刊物主题：Monitoring/Environmental Analysis; Environmental Management; Ecotoxicology; Atmospheric Protection/Air Quality Control/Air Pollution; Ecology;
• 出版者：Springer International Publishing
• ISSN：1573-2959
• 卷排序：189

文摘

The quality of highway pavement is greatly influenced by the subgrade materials, the general geology of the area, and the materials used for construction. Investigation into the 75-km Nsukka-Adoru-Idah highway revealed that the pavement was underlain by three lithological units—Imo, Nsukka, and Ajali formations. The geotechnical evaluation carried out in the study includes the particle size distribution, Atterberg limit, specific gravity, compaction tests, and California bearing ratio (CBR). The base course has clay/silt (7–14%), fine sand (1–4%), medium sand (6–13%), and coarse sand (65–86%), while the subgrade presented clay/silt (74–82%), fine sand (6–9%), medium sand (10–17%), and coarse sand (1–3%). The average specific gravity results for the studied base course and subgrades are 2.58 and 2.52. Liquid limit (LL) result ranges from 27 to 60%, while plastic limit (PL) ranges between 17 and 24%, and plasticity index (PI) ranges from 5 to 39%. The maximum dry density (MDD) result ranges from 1.70 to 2.10 mg/m3, while the optimum moisture content (OMC) for the samples ranges between 14.1 and 18.0%. The CBR result for soaked and unsoaked samples ranges from 37 to 74 and 48 to 83%, respectively. The low unsoaked CBR (<80%) and high Atterberg limits (LL > 30% and PI > 12%) failed the stipulated Nigerian standard, signifying the need for stabilization. A geotechnical model of a highway road cut generated a factor of safety of 1.45, indicating possibility of slope failure.