According to the tunnel in paleosol strata of Xi′an subway

it is analyzed that the mechanism of the shield tunnelling-induced ground settlement

the numerical simulation process of shield tunnelling

and the Peck empirical equation the grouting filling ratio

the shield pitch ratio and the support pressure ratio are introduced into the calculation method of equivalent circal zone thickness.The relationship between the moduli of equivalent circle zone and the support pressure ratio

and the maximal settlement and the settlement troug width of the Peck empirical equation are researched.The following conclusions are drawn: when shield tunnelling in paleosol strata is simulated

the values range of equivalent circle zone moduli are from 5 MPa to 10 MPa.When the equivalent circle zone moduli are less than 5 MPa

the tunnel rock will cause plastic deformation.The values range of support pressure ratio is from 0.5 to 1.When the support pressure ratio is less than 0.5

the tunnel rock will cause plastic deformation.When the support pressure ratio is greater than 1

the ground will rises gradually.