Researches On Railway Engineering Geological Problems Of Red Layers In The Eastern Area Of Sichuan

Red layers are predominantly fragmental sedimentary rocks of red continental deposit, which typically consist of sandstone, muddy siltstone, siltstone, and shale, etc. Red layers are low in permeability, high in hydrophilicity, low in strength, easily soften in water and disintegrated if dehydrated, so the slopes of red layers are easy to slide, which causes lots of geologic hazards during construction. Expansion and reconstruction railway project from Dazhou to Chengdu is located in the eastern part of Sichuan where red layers are well developed. Due to special engineering characteristic, it results in greater influences on construction and operation of the railway. Based on regional geology investigation, exploration, in-situ testing and laboratory and field experiments along the line, detailed studies have been carried out on engineering geology characteristics of red layers in the eastern part of Sichuan with the combination of mathematical analysis and engineering example in this paper.Compositions, constitutional features and physical mechanic properties of red reds and relations between them were systematically studied with statistics and analysis of material composition, rock and soil physical and mechanical parameters as well as results from representative sample disintegration and creep experiments, which reveals that the physical structures of red beds are the inner to determine physical mechanic properties, and play a key role in the engineering geological properties. At the same time, the physical and chemical effects of water on the red layer and the erosion of water on the concrete were also studied with statistics and analysis of water chemical characteristics along the line.At last according to the main engineering geological problems of red layers along the line, the effects of red layers on roadbed and bridge, tunnel, and the limitations as subgrade filling with engineering examples, and the corresponding countermeasures and suggestions were given.