Typical Soil Body Deformation Characteristics And Land Subsidence Prediction In Zhengzhou Area

Ground water exploitation-land subsidence prediction is an issue to which geologist pay close attention all along. The North China Plain has been one of the most water over exploitation and the biggest land subsidence areas in the world.This work takes the G1 drill in the typical region of land subsidence in Zhengzhou area as the research object, which situates in the south part of the North China plain. We have measured parameters such as coefficient of the soil compressibility, specific weight, density, moisture content etc., carried out research of soil compression deformation characteristics and land subsidence prediction, and we obtain results and conclusions as follow:(1)Soil compression deformation characteristicThe soil is characterized by medium compressibility. The rules of physical parameters variation with depth are:there are trends that with the increase of depth, the compression coefficients and porosity ratios decrease, the density and dry density increase, and the specific weight, moisture content and saturation fluctuate. These reveal the mechanism of soil body compression deformation that:the soil compression is mainly influenced by deadweight of soil body; relativity analysis show that compressibility coefficient positively relates with initial porosity ratio and remarkably reversibly relates with density.(2)Groundwater exploitation-land subsidence predictonThere is similarity between over-consolidated soil stratification method and multiple groundwater heads distribution method. When the water level drop by 30 meters,60 meters and 90 meters, respectively, the quantities of accumulated subsidence predicted by the two methods are 640.5、1242.6 mm,1932.7 mm and 560.0 mm,1120.1 mm,1680.1mm, respectively. The results of over-consolidated soil stratification method are greater than that of multiple groundwater heads distribution method. This is because the effective stress influence of over-consolidated soil stratification method is not restricted in exploitation of water-bearing system, and the greater the water level drops, the greater the stratum thickness is influenced, therefore the greater the prediction results; the effective stress of multiple groundwater heads distribution method only influences the exploitation of water-bearing layer system below the water level, the drop of water level does not influence the soil body thickness of effective stress, and the compression coefficient is decrease with the soil depth, which cause the smaller prediction results.