Study On The Characters Of Deformation And Stability Of High-fill Airport Embankment In Mountainous Areas

With the development of national economy,the implementing of Development of West Regions and the construction of large-scale basic establishment for expanding domestic demand nowadays, the airport construction in the mountainous southwest of China is coming into a prosperous period,where a great deal of airports have been built or renovated. Compared with the middle and east regions, the airport construction in mountainous southwest, face a series of special engineering problems, such as high embankment, high altitude, intensive earthquake, high slope, complex geological conditions accompanied with soft soil, bad climate condition, short construction period and strict project quality requirements are the main characteristics for these airports.The fillings of high-fill projects in the mountainous southwest of China come from the blasting of large particle size block detritus usually, and over coarse-grained soils are the most common fillings. From the engineering practice in the past time, the building of mountainous high-fill airport mainly faces three urgent problems in the current:1.The control problem of compaction quality with over coarse-grained soils.2.The settlement calculation problem of over coarse-grained soils filling.3. The stability of high-fill slope, especially the stability under the conditions of the earthquake. Based on the typical problem encountered in the high-fill airport construction in western mountainous, the main contents are studied as follows:1. The current civilian airfield design code for the strength and deformation of soil foundation is not clear, it bring some practical difficulties for engineering application. To determine the appropriate criteria of subgrade strength and deformation for airport concrete pavement, the effects of four parameters, including subgrade strength, base course thickness, base course modulus and concrete flexural strength, on concrete slab thickness were analyzed and compared based on pavement design procedure. Through the finite element numerical simulation method and theoretical analysis, the influence of subgrade deformation on pavement structural and functional performances was also studied.2. Nowadays over coarse-grained soils are widely applied in high-fill engineering practices in mountains areas, but such problems as compacting standards,quality inspection and evaluation are not clear to these days, so they can not satisfy actual application requirements. In this paper compaction effect factors and compaction quality control indexs for over coarse-grained soils are analyzed; Compaction standards and the connection of dry density with intensity and deformation standard indexs are studied as well; a new method (visual compaction) to evaluate the relative compaction degree of filling is putting forward. In this section two engineering examples are introduced, one is the compaction treatment engineering of the over coarse-grained soils filling in Kangding airport, the other is the compaction and stamping processing project in Kunming airport, at last some practical compaction quality control methods are put forward.3. A large proportion is occupied by the settlement of filling embankment in the settlement of high-fill foundation. For its own compression settlement of filling embankment,There is no general deformation calculation method. Take section B of Kangding airport high-fill filling embankment for example, the construction of soil surface areas are measured, and Gompertz living curve model is used to forecast the high-fill foundation settlement. Compared with Logarithm model and Hyperbolic model, we can find out that the effect of settlement forecasting of Gompertz living curve model is best.4. Deformation and stability of the embankment are two major problems in the construction of mountainous high-fill airports, highways, railways. Based on the finite element method with strength reduction technique, according to two basic characteristics--flat foundation and slope foundation, the deformation and stability of mountainous high-fill embankment are analyzed considering such influencing factors as original foundation, landscape, the filling speed, filling compaction degree, groundwater, sustaining structure, loading berm etc.5. Under seismic load of the slope dynamic response and stability is the current hot and difficult problem of geotechnical engineering. Using finite element software for earthquake time-history analysis, analyzed displacement and acceleration under the different seismic load, slope height, slope ratio, seismic waves factors (including amplitudes, frequencies, duration time), soft soil layer and so on. Based on the analysis of the slope dynamic response characteristics, destruction mechanism under seismic load and the slope dynamic method to determine the safety factor are put forward. In the research, Yuan shan zi channel of Jiuzhai-Huanglong airport high-fill slope stability under earthquake is analyzed, and compared different methods meanwhile.