Study On Construction Technology And Deformation Regularity Of Fluvioglacial Deposits Subgrade In The Leshan-Ya’an Highway

Based on the national highway network, the Chengdu-Chongqing region link Leshan-Ya’an section, this paper comprehensive considerate many factors such as spoil ground for fluvioglacial deposits and sub-grade filling costs, and put forword using fluvioglacial deposits and sand gravel aggregate sandwich in sub-grade construction. The best moisture capacity and the maximum dry density of fluvioglacial deposits are determined by heavy compaction test in the construction process. The particle-analysis of test indicate that fluvioglacial deposits samples lack of intermediate diameter and belong to difficulty compacted sub-grade filler. The design and operation parameters, service conditions, the position and number of "sandwich" layers, loose laying thickness, the best moisture capacity and the maximum dry density and so on are obtained in the construction process.The monitoring on the on-construction process and post-construction settlement of sandwich method and sand gravel directly method is conducted, and concludes that the settlement trend is large on middle and small on both ends, and horizontal differences settlement is not too large. The horizontal differences settlement of sub-grade is occurred in embankment filling period. The analysis of the deformation of road surface subsidence verified that fluvioglacial deposits and aggregate sandwich method can accelerate fluvioglacial deposits soil drainage consolidation, and cushion and aggregate sandwich can be used as the good row of the water, so as to make the foundation of the pore water pressure dissipates rapidly, and accelerated consolidation of fluvioglacial deposits layers.The in-site actual measurements show that the subgrade settlement with fluvioglacial deposits and aggregate sandwich method basic stable after construction20days or so, and the settlement is far less than the maximum of Design of Highway Sub-grades. Thus fluvioglacial deposits and aggregate sandwich method can satisfy the basic requirements of the design is explained.Through the Plaxis finite element analysis software to consider in the compaction process of each layer groundwater seepage drainage consolidation and the value calculated the final settlement. The analysis of the drainage effect of sandwich method can indicate that subsidence mainly in the construction process, settlement after construction is very small. From the theoretical level shows fluvioglacial deposits and aggregate sandwich method, cushion and aggregate sandwich can be used as the good row of the surface of the water, can make the foundation of the pore water pressure dissipates rapidly, accelerated consolidation of fluvioglacial deposits layers.