The researchers studied how coal mining under thick alluvium affects rock strata and surface displacement. They used curve and probability integration methods to analyze data from three observation stations. They found that mining causes significant surface ground changes, with subsidence values under 200 mm in most areas. Cracks can appear 200 m from the mining face edge, parallel to the coal face. The starting distance for effects is 1/4 to 1/5 of the average mining depth, with an advanced influence angle of 60°58′00″ to 83°58′13″.