From overburden layers

semipervious layers above depression-cone level drainage consolidation

porous media (geo-formation) compression and water compression

the ground settlement mechanism is analysed during foundation pit dewatering. Compression layers thickness due to dewatering is chiefly overburden layers

semipervious layers thickness above depression-cone level. Collecting the related data of 10 foundation pits dewatering engineerings

the practical values and theoretical values are compared and a set of modified-coefficient of surrounding ground settlement due to foundation pit dewatering (aggregately 880 groups of data ) are got. Using BP neural network method to process those data

we can find a sort of net mapped connection between given inputs and outputs ( ).We can use net connection to input a sort of

and get isoline of modified-coefficient which is corresponding with different

S. Accordingly we can find modified-coefficient of arbitrary ，S

which has practical value to foundation pit dewatering engineering of similar layers to forecast practical settlement at different times and distances from foundation pit.