Abstract: Based on the Bao′ an- Bihai shield tunnel of Shenzhen metro line 11, the law of ground settlement caused by shield tunnel construction in sand/clay compound strata is studied by field tests and the finite element method. By fitting the field-measured data of ground surface settlement at the cross section with the Gaussian Peak Function, the key parameters for the coefficient of the settlement trough width, maximum settlement and ground loss ratio--which represent the characteristics of settlements at the cross section--are obtained. The coefficient of the settlement width in the sand/clay compound stratum is smaller than that in soft soil strata and larger than that in sand and cobble strata. The influence of the tunnel's buried depth, the conditions of the overlying strata and the strata conditions of the main tunnel on ground surface settlement are studied by numerical simulations and field-measured data, with results indicating that ground surface settlement is influenced significantly by the overlying strata conditions and closely related to the properties of the strata approaching the ground surface.