埃塞俄比亚黑棉土胀缩特性及大气影响深度研究  

Research on the Black Cotton Soil Swell-shrink Characteristics and the Depth of Black Cotton Soil Influenced by the Atmosphere in Ethiopia

作　　者：赵平[1] 徐正宣[1] 唐林[1] 曾德礼[1] 

机构地区：[1]中铁二院工程集团有限责任公司,成都610031

出　　处：《铁道工程学报》2014年第4期46-50,共5页Journal of Railway Engineering Society

摘　　要：研究目的:埃塞俄比亚在建亚的斯亚贝巴至吉布提铁路Sebeta-Dire Dawa段,地处东非大裂谷内,为火山喷发物覆盖,地表广泛分布黑棉土,多具强膨胀性,对铁路工程影响大。黑棉土的胀缩特性及大气影响深度直接影响路基设计措施和路堑换填深度,进而影响工程设计质量和投资。因此,有必要对黑棉土的胀缩特性及大气影响深度进行研究,为黑棉土地段路基设计提供依据。研究结论:(1)埃塞俄比亚黑棉土天然密度、干密度小,天然孔隙比大,自由膨胀率、蒙脱石含量、阳离子交换量高,含有机质(灼烧失量),多具强膨胀性等特性;(2)埃塞俄比亚雨季黑棉土在荷载作用下主要表现为压缩,旱季地表土在浸水条件下具有较强的膨胀性;(3)埃塞俄比亚黑棉土(膨胀土)地区大气影响深度为3.5 m,大气影响急剧层深度为1.6 m;(4)本文对埃塞俄比亚类似工程项目的地质勘察和路基设计具有一定的参考意义。Research purposes： In Ethiopia, the constructed Sebeta - Dire Dawa section of Addis Ababa - Djibouti Railway, is located in the East African Rift Valley covered by volcanic material, and its surface is widely distributed with black cotton soil which has strong expansibility, as a result, the railway engineering has been greatly influenced. The swell - shrink characteristics of black cotton soil and the depth of it influenced by the atmosphere will directly affect subgrade design measures and the replacement depth of cutting, which will further affect the quality and investment of engineering design. Therefore, the proposed research on the swell - shrink characteristics of black cotton soil and the depth of it influenced by the atmosphere is necessary, which provides design basis for subgrade of black cotton soil section. Research conclusions： （ 1 ） The black cotton soil of Ethiopia has following characteristics ： small natural density ＆ dry density, big natural void ratio, high free swell ratio, high montmorillonite content ＆ cation exchange capacity, organic matter （loss on ignition） and strong expansibility, etc. （2） In rainy season, the soil is mainly shown as compression when there is load ; in dry season, it has relatively strong expansibility under the condition of immersion. （ 3 ） The depth of black cotton swell soil area influenced by the atmosphere is 3.5m and the depth of it distinctly influenced by the atmosphere is 1.6 m. （4） This article will be a reference to geological survey and subgrade design of other similar projects.

关 键 词：黑棉土 胀缩特性 大气影响深度 

分 类 号：P642[天文地球—工程地质学]