Abstract：Because tunnel construction inevitably disturbs stratum，ground settlement with different degree is generated resulting in unfavorable effect on safety of subway construction and surrounding environment，such as roads，bridges，underground pipelines and ground buildings in urban districts. So it is necessary to define guideposts of ground settlement scientifically to reduce or avoid unfavorable effect caused by ground settlement. Based on many in-situ investigations of projects，statistic analysis for measured data with fuzzy cluster analysis，and consideration of economy of engineering construction，the method and controlling value for defining ground settlement guideposts are given，which is important to guide tunnel construction.
