Abstract:

The variation laws of composite ratio of sandyclay composite strata with tunneling parameters of shield in Bailiu Section tunnel project of Shijiazhuang Metro Line 1 are studied. Based on the site shield tunnel test, the standard thruststandard torque characteristic space is established by the secondary conversion of the original tunneling parameters of shield, and the traditional shield tunneling velocity model is modified. The results show that: (1) Under the normal tunneling condition, there is a logarithmic relationship between standard thrust and standard torque; with the decrease of composite ratio, standard thrust and standard torque increase. (2) According to the distribution of parameter points in the characteristic plane and corresponding construction state, the characteristic plane is divided into zoneⅠ (normal tunneling zone), zone Ⅱ (excessive torque zone) and zone Ⅲ (excessive thrust zone); and according to the different composite ratios, the normal tunneling zone is further divided into zoneⅠ1 , Ⅰ2 , Ⅰ3 and Ⅰ4 . (3) Based on the standard thrust and standard torque, a prediction model of tunneling velocity for sandyclay composite strata is established.

Key words: shield, sandyclay composite strata, composite ratio, shield tunneling parameters, standard thrust, standard torque, tunneling velocity prediction model