陕西黄土承载比值区域性分布规律

Regional distribution of CBR value of loess in Shaanxi Province

加州承载比(CBR)值为表征路基填料强度的一项重要指标,其值大小直接影响路基工程的质量和经济效益。由于黄土分布区域较广,其成分不尽相同,所表现工程性质随区域分布不同有所差异。以陕西黄土为研究载体,结合其区域分布特点,选用陕西榆林横山狄青塬、延安洛川黑木沟、咸阳旬邑下墙和渭南临渭吴田为典型黄土剖面,按地质年代分层,对各层黄土分别做CBR试验,分析其CBR值随区域分布规律和工程地质力学机理,结果表明:陕西黄土CBR值区域性分布规律与其地质地层构成、黏粒级含量、矿物及其黏土矿物含量有关联,CBR值整体呈现由西向东、由北至南减小趋势;按现行相关规范衡量,从不同地质地层分析角度而言,陕西黄土CBR值相差不大,偏差量最大不超过0.4%.黄土CBR值总体分布在1.42%~3.60%之间;整体黄土(L)和古土壤(S)所表现工程性质截然不同,前者CBR值明显高于后者;全更新世黄土CBR值高于其他3个时代黄土CBR值;同一地质年代各区域黄土CBR值基本相同;Q2地层黄土CBR值高于Q1地层黄土和Q3地层黄土CBR值。

California bearing ratio(CBR)value is an important index to characterize the strength of subgrade filler,and its value affects the quality and economic benefits of subgrade engineering directly.Because of wide distribution of loess area,the composition of loess is different,and performance of loess varies with the distribution of region.Taking Shaanxi loess as the research carrier,combined with its regional distribution characteristics,using Diqingyuan of Shaanxi Yulin Hengshan,Heimugou of Yan’an Luochuan,Xiaqiang of Xianyang Xunyi and Wu Tian of Weinan Linwei as typical loess sections that were stratified according to the geological age of loess layer,we tested california bearing ratio(CBR),and analyzed the distribution of CBR value and its mechanism.The results show that the regional distribution of CBR value of Shaanxi loess is related to its geological formation,clay grade content,mineral content and clay mineral content at the same time,and the CBR value shows a decreasing trend from west to east and from north to south;according to the current standard,from different geological point of view,the CBR value of Shaanxi loess has little difference with the maximum deviation of no more than 0.4%.And CBR value of Shaanxi loess overall is between 1.42%and 3.60%;the CBR value of loess(L)value is significantly higher than Paleosol’s(S);the Pleistocene loess CBR value is higher than the other 3 age’;Q 2’s CBR value is higher than Q 1’and Q 3’.