To alleviate the tensity of construction land in Lanzhou,there was a project of truncating the mountain,filling in the ditch and preparing land.On the basis of analyzing the characteristics of natural and human environment in the foreordained land preparation regions,it was forecasted that the land preparation project would affect the ambient air,the soil erosion,the land utilization and the afforested condition and so on in Lanzhou.Measures of preventing the construction fugitive dust and reducing adverse environmental impacts were proposed.Then the technical support was provided in order to develop barren hills and gullies in reasonable order and ensure ecological environment securities.

Saturation line is the lifeline of tailing dam.This article analyzes one tailing dam saturation line by finite element method,the conclusions are:(1)The tailing dam saturation line is related with the drawing beach length,with the beach length increasing,the saturation line become far from the grit dam body.When beach-length is more than 70 meters the saturation line away from the dam's foot according to the conclusion of finite element simulation,the dam is stable.(2) The tailing dam is built on the strong water penetration site,the dam's height influences saturation line isn't distinct in the dam's foot.

Using dry jet mixing in soft soil treatment is a well-known method. However, the above method is first used in Gansu province to improve the saturated loess soil and no relative calculation parameters are found in regulations. The application of dry jet mixing and its design parameters were given by investigation, in-situ testing and bearing capacity test on treated saturated loess at Yin-Zhong Expressway in Gansu Province.