THEORETICAL ANALYSIS OF INTERACTION BETWEEN SURROUNDING ROCKS AND LINGING STRCTURE OF SHIELD TUNNEL BASED ON DRUCKER-PRAGER YIELD CRITERIA

In calculating the load for segment lining structure of shield tunnel, the soil column or pressure arch theory are often used to describe surrounding rock loosening pressure.But when it comes to the deep-buried condition and the deformation pressure should be calculated, this method is considered as unreasonable and is difficult to apply.In view of this, based on the Drucker-Prager yield criterion, an analytical elasto plastic solution is derived for the interaction between surrounding rock and lining structure considering the influence of seepage effect, and the formula of the relationship between the support pressure and some key parameters such as the stress and displacement of surrounding rock elastic and plastic zone as well as the radius of the plastic zone is given.The analytical results can be applied in the determination of the load of the lining structure by establishing the static equilibrium state of the surrounding rock and the lining structure and finding the intersection point of the two curves.Further, rigidity reduction factor is induced to equivalent considering the influence of the overall rigidity decrease of assembled segment liner for the existence of joints to the interaction of surrounding rock and lining structure.In the load determination, the influence of the fluid-solid coupling effect during construction and seepage force on support characteristic curve of lining structure is also simplified considered.Finally, an engineering instance of underwater shield tunnel is introduced to compare the calculated load with the measured value and numerical simulated value.The results show that the caculated analytical load values of segment lining structure are greater by 28% and 12% comparing to measured values during the construction period and the stable period, and are greater by 5% comparing to numerical simulated value during the stable period, respectively.The research results of this paper can provide some reference for the design and construction of similar projects.