The Study Of Effects For Additional Stress Field Under Urban Environment Of Kunming

The rise and development of environmental geotechnical engineering were reviewed. The research objects and contents are discussed. On this basis, the research method for environmental geotechnical engineering also is studied. This paper holds that combining qualitative and quantitative of comprehensive integrated method is a scientific method at present. Recent research advances on urban environmental effects both at home and abroad were presented. Research content, theory and practice meaning of this paper have been described.Kunming, which is political, commercial and trade center of southwest China, is located Yunnan-guizhou plateau. With the acceleration of urbanization, production, life and a great number of construction activities have caused many environmental geotechnical engineering such as slope failure, land subsidence and foundation pit failure etc. These problems have been increasingly obvious.The definition of additional stress field by the domestic scholars is modified. The internal and external factors of additional stress field have been described on this basis. The external factors can be concluded to load field, hydrochemistry field, temperature field, electromagnetic field and so on from the field angle. The stress in soil-body is called additional stress field due to change of external environment.According to the observation data during the year of 1979-1998, increasingly severe land subsidence has been happened in Kunming city. The hydrogeology condition and engineering geological condition in Kunming area is firstly introduced. A great deal of additional stress field's problems may be produced due to the fluctuation of groundwater level. The mechanism of land subsidence owing to groundwater over-exploitation is revealed. For one, there is a compressive effect for soil. For another, there is an action of consolidation settlement for soil. There is large thickness of high compressibility soil layer, which is the basic reason for large land subsidence in Kunming city. Then the countermeasure is proposed for land subsidence controlling in Kunming city.The additional stress field will be produced in soil due to city construction. It has unneglectable contribution for regional land subsidence. The deformation influence depth of building complex is discussed. The influence depth is bigger than single building load, but is smaller than the one calculated by routine methods through analysis. The effects of ground settlement under different construction process and construction mode are simulated by FLAC-3D. The results show that the settlement of equivalent load is the biggest, and the settlement of one-by-one constructing mode is little larger than concentration constructing mode's.Foundation pit engineering has the character of complexity, systemization, uncertainty, etc. It involves strength, stability, deformation and the interaction problems between soil and foundation pit retaining support. Foundation pit engineering may induce many additional stress field's problems. Land deformation as one of problem has the character of universal and catastrophic. An engineering example is analysised by FLAC-3D and compared with monitoring date and Peck method. The results show that the value of numerical simulation is basically identical with monitoring data.