Shallow Subway Construction Of Water-rich Composite Stratigraphic Impact On Adjacent Buildings

As the rapid urban infrastructure development, more and more urban subway and underground engineering projects being invested in the country. However, not only the excavation often located in soil layers with complex geological, hydrological conditions, but often need to pass through or near buildings. So, it is very worth to study how to take effective analysis and evaluation methods to predict and avoid the potential damage risks.The Shenzhen Subway (Line 5) Project (SSL5P) provided a unique opportunity to study the effects of tunneling in water-rich stratum beneath or adjacent a wide range of buildings. Through theoretical analysis, field measurement and numerical simulation, this paper presents the main content as following:(1) By analyzing field data, the basic law of ground movement and deformation caused by tunneling in water-rich and complex formation stratum was summed up; the applicability of the settlement prediction methods based on Peck formula and considering the hydrophobic soil consolidation was discussed, also the reasons for large volume loss of stratum caused by tunneling were analysed.(2) By summarizing calculating methods and basic rules of playing the role for the building stiffness, analysis method was proposed to analyze how the building relative stiffness affect the building deformation caused by tunnel excavation; Based on a large number of observed data on greenfield and buildings, the basic law of how the relative stiffness affect the deformation of building structures induced by tunneling was analyzed for strip footing and pile building respectively.(3) The control parameters that regulate the behaviour of the building towards tunneling induced settlements were analyzed in a comprehensive way, then a synthetic evaluate method was suggested which was based on the weight of the control parameters. This method was carried out on typical buildings in the SSL5P, the evaluation result is basically consistent with the real situation.(4) The ground movements and deformations induced by tunneling were simulated by using the numerical simulation software (ABAQUS), and their effects on adjacent buildings were assessed, also the response characteristics towards settlement on superstructure and foundation of the buildings were discussed.Results show that due to the effects of building stiffness, tunneling induced settlement under the buildings is less and smooth than that on natural field, and this trend depend on the building relative stiffness, foundation form and eccentricity ratio.