Sediment and engineering properties research on the Xiaozhongdian lacustrine clay in Northwest Yunan Province
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摘要: 滇西北小中甸盆地是上新世末期以来在青藏高原强烈隆起过程中形成的NNW向第四纪断陷湖盆地,从深切的小中甸河谷剖面可见盆地上部发育中晚更新世湖相粘土。规划建设中的滇藏铁路将从小中甸盆地穿过。野外调查发现小中甸湖相粘土厚数十米以上,粘土细腻、层理发育。室内试验表明:小中甸湖相粘土是一种高分散性、高含水量、高塑性和高孔隙性的结构性粘土,其力学性质指标表现为高粘聚性、以中低膨胀性为主。工程开挖卸荷、浅表层土体暴露在干湿交替环境中,土体收缩强度衰减,由此产生土体差异变形和粘土边坡滑塌破坏。Abstract: Xiaozhongdian Basin is a NNW-directed fault depression basin which was shaped while the Qinghai-Tibet Plateau intensely upheaved since the end of the Pliocene epoch,where the lacustrine clay of the middle and late Pleistocene is well distributed from the Xiaozhongdian River section.The Yunnan-Tibet Railway in planning will pass through the Xiaozhongdian Basin.The depth of lacustrine clay is above ten meters,which is obviously fine and has texture layer from the outcrop of the Xiaozhongdian.The laboratory testing results indicate that the Xiaozhongdian lacustrine clay is a kind of clay with high dispersion,high liquid limit,high plastic limit and high porosity ratio,whose mechanical characters are high shear strength and low expansibility or middle expansibility,so its engineering property is better.The slope will be destroyed when it experiences alternations of wetting and drying.
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