Study On Small Disturbance Control For Shield Crossing Adjacent Dilapidated Buildings

There is high risk of shield tunneling in soft soil when crossing buildings that are sensitive to deformation, such as badly inclined dilapidated buildings. Based on the engineering practice of rail transmit construction in Shanghai, in this paper, it was studied that the characteristics of ground displacement and building settlement and its influence factors, as well as the method of building security analysis when shield crossing dilapidated buildings. Finally, small disturbance control method for shield crossing dilapidated buildings was summarized.(1) By three-dimensional numerical simulation, it was analyzed that the characteristics of ground displacement field and building settlement caused by front pressure and stratum loss, as well as the regularity of the alteration of dynamic ground displacement field. In addition, the factors in displacement field were studied. In addition, the distribution of the ground displacement caused by shield tunneling with ground buildings was described with the modified Peck formula.(2) Based on the analysis result of the building foundation settlement, the building security analysis for masonry structure was done, including the effect of inclination and non-uniform settlement on longitudinal wall and cross wall (bearing wall). For the effect of non-uniform settlement on masonry wall, four kinds of settlement models were presented, and based on that, the development of wall crack was analyzed. Finally, control target of stratum loss was set according to the prediction of the ground displacement field and building security situation.(3) With the results of numerical simulation, small disturbance control method for shield crossing dilapidated buildings was presented.(4) The measured data from engineering practice was analyzed. Integrating the measured data of ground settlement, disturbance on stratum, building settlement and construction parameters, the regularity of ground displacement filed and building settlement was emphatically analyzed, which verify the validity of the theoretical calculation result and small disturbance control. The achievements of this paper indicate that, there are particularities of the displacement field and the construction control when shield tunneling crossing dilapidated buildings. And the deformation of ground and building is sensitive to the construction parameters. As a result, for shield tunneling in soft soil across dilapidated buildings, it's necessary to elaborately control the shield construction parameters in order to reach the small disturbance construction.