Study On The Design Of Mountain Highway Route In The Different Geological Conditions

With the rapid development and strength of China’s economic construction, highwayconstruction to the complexity of geological environment in large extend, in order to minimize theimpact of geological hazards on the highway engineering construction and operation, reduce thehuman engineering activities damage of geological environment, strengthen the mountainous areahighway line selection, analysis and evaluation of Engineering geological conditions and theenvironment and the comparison research, it has important practical significance.In the highway and summarized the domestic and foreign common geological disasters inmountain areas, form and formation conditions, along the highway roadbed, tunnel, possiblebridge engineering geological problems, analyze the causes, and according to the forms of thedisease, genetic mechanism, the mountainous area highway engineering geological explorationand the basic principle and key points of follow. In Hunan, Sangzhi to Zhangjiajie of the highwayas an example, discriminant method combined with the stability of engineering geologicalenvironment, the route to analyze the stability of engineering geological environment areas, andfollow the new concept of road design, line selecting principles of engineering geology proposedthe mountainous area highway:1） crossing section geological line selection. Should first choose the time pass, elevation,the research on both sides of the line, to avoid the line selection in the regional faults or extrusionbelt by location, should try to choose the mountain, geological structure is not developed in rocktendencies, terrain slope slow, less damage to section.2） along the Creek Road geological line selection. Should choose a bank geologicaldiseases in undeveloped and slope gently; when the river terraces can use, should as far aspossible along the terrace routing; cross layer development road, the route choice as far as possiblein the gentle terrain, stacking layer thickness is smaller, and the upper catchment area.3） landslide section geological line selection. Line landslide through to does not deterioratelandslide stability as a principle, especially selected by favorable for landslide stability and routessafe area. According to the relative position of line of landslide section height selection of wiringposition, namely through the upper edge of the landslide area, excavated roadbed is appropriate, toreduce the sliding body weight; the lower margin area, the embankment is appropriate, to increase its anti sliding force.4） collapse rock pile section geological line selection. Such as the terrain conditions allow,should be in the rock pile toe line outside the proper distance to the embankment through; such asrestricted by terrain, must pass, should avoid large fill dug, and strive to not destroy the rockstability itself, can be given by the low embankment or shallow cutting.5） road segment of debris flow geological line selection. The route should not be laidaccumulation area in the stage of development of debris flow; when the flow area of gully bednarrow stable to use, can be considered early elevation line, a bridge crossing; if does not have theconstruction conditions, can consider to tunnel through or cut programmes; route should beavoided in the diluvial fan is arranged on the cutting, set and no compression channel bed section,longitudinal slope of gully bed should meet the requirements of debris flow.6） karst geological line selection. As far as possible to avoid the strongly developed karstarea, the line layout in the corrosion degree is low, is not the development of karst area throughavoidance; if there are difficulties, as far as possible to make the routes and their orthogonal oroblique, and choose the most narrow, the most easy to take engineering measures parts through;pay attention to the route selection is higher than the highest flood water in Karst elevation ofdepressions and edge through the valley.7） the goaf road geological line selection. In the special reconnaissance basis, as far aspossible to choose layer thin, buried depth, inclination ease favorable position perpendicular to thedirection of ore, and the goaf filling processing necessary.8） required by bridge and tunnel sections of the geological line selection. Based on theengineering geological stability evaluation on the security of the engineering geological conditions,selection of good roads construction.In Hunan Province, the Sangzhi to Zhangjiajie expressway as an example, carried out thegeological line selection research practice of Expressway in mountainous area, and combined withthe engineering quantity, the cost factors, long-term social benefit, the comprehensive comparisonof line selection scheme, the optimum route scheme. Safety evaluation at the end of the selectedroute engineering geology condition, proposed the project proposal.