The Impact of The Building Load on Subsidence in Beijing

Beijing is one of the most serious areas suffered from land subsidence in China. A series of environmental geological problems, such as the elevation loss caused by ground subsidence, have become one of the important factors that affect the urban planning and construction of Beijing and the sustainable development of regional economy. In recent years, land subsidence in Beijing is still at a rapid development stage. In addition to the groundwater over-exploitation, the scale of urban construction becomes a factor for the ground subsidence. The engineering-environmental effects of multilayer, high-rise buildings have more obvious effect on the ground subsidence. It is very important to analyze the relationship between the building load and ground subsidence. This work would be beneficial to the reasonable planning of buildings, to the predicting and analyzing of the ground subsidence, and to the reduction the hidden danger caused by ground subsidence.The Floor Area Ratio is an important index to measure the land use intensity, and it can reflect the building load. In this paper, the Floor Area Ratio index is used as a direct index to reflect the building load on the surface. The new index is extracted using the building shadow information on the GeoEye-2 images. By establishing a relationship among the shadows, building height and building load, the index can be calculated. The subsidence data can be obtained with InSAR(Interferometric Synthetic Aperture Radar) technique. The correlation coefficient method is used to analyze the relationship between ground subsidence and building load in typical area of Beijing.The results show that the impact of the building load index on the ground subsidence has a small scale feature in spatial. The building load index has a good response relationship with the ground subsidence in the local area, but there is no such law on large scale. Among the build-up areas, the central business district(CBD) area in Beijing has a cluster of tall buildings. The accompanying huge-scale static load and construction dewatering stand out as a factor for the subsidence. It has positive correlation between the building load and subsidence at local build-up areas. However, the law may not be applicable to all regions that with complex geologic environment, engineering environment, land use and groundwater exploitation.