长江口细砂作为路基填料的工程特性研究

选择了有代表性的5种长江口细砂进行级配、压实特征、湿度特征、回弹模量的室内和现场试验.结果表明:长江口细砂粒径较为单一,多在0.075～0.300mm之间,不均匀系数小于5;采用小型试筒重型击实试验可减小击实对周边压实砂粒的扰动,且最大干密度测试结果高于大型试筒;击实曲线呈现多峰特征,含泥量越低,驼峰数越多,对现场施工压实控制更为有利;低填细砂路基在运营过程中受地下水影响较小,CBR强度和回弹模量与压实度、含泥量相关性显著,能满足设计要求,且经100万次加载后无显著衰减.

Engineering Properties of the Fine Sand of Yangtze Estuary for Subgrade Filling

It is of economic and social benefit to use the fine sand of Yangtze estuary as subgrade filling, which not only can avoid the shortage of materials, but also is an effective utilization way of sands for dredging Yangtze channel. However, the engineering properties of fine sand are different from the ordinary filling materials because of the fine grain and bad gradation of the particles. So a series of laboratory and field tests were performed for five kinds of fine sand of Yangtze estuary, including the experiments of sieve analysis, compaction characteristic, water content and modulus. The diameters of fine sand mostly ranged from 0.075 to 0.300mm, the non uniform coefficient were less than 5. The maximum dry density from modified standard compaction with small tube is higher than that with big tube, because the former can avoid disturbing compacted fine sand. The compaction curve has a few peaks, and the less content of fine particle, the more numbers of the curve peak, that is useful to compaction control in field. The fine sand is usually less affected by groundwater; the modulus can meet the requirement of the design and has significant correlation with compaction degree and content of fine particle. Moreover, the performance of low subgrade with fine sand does not degrade significantly after one million load repetitions.