Feasibility of Coupling PS System with Building Protection in an Ultrasoft Strata Colliery

Abstract

To guarantee the stability of a building complex above a planned mining district with ultrasoft strata, strip mining technology (SMT) was applied to control the displacement and deformation caused by underground exploitation. This study attempts to design a reasonable pillar width to establish a stable pillar-support (PS) system composed of ground buildings with coal pillars underneath. Based on the stratigraphic structure of ultrasoft strata and in situ measurement data of mining subsidence monitoring, this study takes an ultrasoft strata colliery in western Henan province, central China, as an example to examine the technical and economical feasibility of the proposed PSsyst under two mining scenarios. The major results indicated that the initial design of pillar width would be 120 m under scenario 1, with expected damage of only 450 mm maximum subsidence predicted by probability integration method (PIM); while under scenario 2, the cost of compensation for buildings’ mining-induced damage would increase to CNY 61.31 million with an expected output of 7.629 million tons of raw coal. Moreover, the protection rate of the residential area in the proposed postmining area of scenario 1 can reach as much as 6.91% comparing to the fully mechanized coal winning technology in scenario 2. Overall, the proposed PSsyst will bring good benefits both economically and environmentally and should be worth promoting as a reference for similar geological and mining conditions in the future.