Underground water biological field＇s variation and geoenvironmental safety in city

In the process of city construction, as a comprised factor of city geological environment, underground water takes the most active part, and its dynamic change is fiercest. The city construction unceasingly disturbs underground water chemical, dynamical, physical and biological field. In return, the four fields＇ changes also can affect the geological environment that city lived by, in other words they affect safety and stability of geological environment. Interaction of underground water and the geoenvironment directly displays in the following two ways： The first is that the underground water and the geological body transfer the energy each other; the second is that the strength balance of geological body is broken. Underground water variation brought about by city construction is the factor which cannot be neglected. Underground water variation on the one hand changes soils or rocks＇ physical, biological, chemical and mechanical properties, then influences the deformation and strength of geological body. On the other hand it changes its own physical, chemical properties and biochemical component. At present, from mechanics aspect, interaction between chemical field and biological field variation of the underground water and the geological body lacks research. Although interaction between them is long-term, slow, but when it compared with water-soil or water-rock interaction in the entire process of formation of rocks or soils or geologic evolution history, the qualitative change of the biological and chemical action of rocks or soils brought about by city construction is remarkable, in this paper, aiming at underground water biological field factor which is easily neglected by people, it analyzes that underground water biological field affects possible mechanism and approach of properties variation of rocks or soils in city construction, brings forward further research method and development direction have been also proposed.