SUBSIDENCE DEFORMATION INDUCED BY UNDERMINED AREA OF NATIONAL COALMINE CORPORATION IN UNDERPLANNED NEW CITY OF NENTOUGOU DISTRICT,BEIJING

Underplanned Mentougou new city located in the SE of Mentougou district,includes Longquan and Yongding two counties and covers an area of 87km2.There is large undermined area of National coalmine corporation distributed.The subsidence deformation induced by the large undermined area is very sensitive to the undergoing plan of the city.The paper studies the distribution of the undermined area,and builds a large numerical simulation model with FLAC3D based on large amount of data of boreholes and maps.The numerical simulation results indicate that the main subsidence deformation induced by the undermined area concentrated at the Tiaoqianfu-Guanting and Yuejiapo-Zhaojiawa,and the maximum subsidence deformation reaches 28mm with limited area.