Research On Mechanic Characteristics And Structures Of Section Joint Shear Keys On Immersed Tube Tunnel

Until now, even rough many researches on immersed tunnel had been taken, the specialstudy on mechanical characteristics and structure shapes of section joints on immersed tunnelwere few. Considering the important role of section joint shear keys on earthquake-resistanceand structure safety, this paper basing on the immersed tunnel of Hong Kong-Zhuhai-Macaubridge engineering, studied the mechanical characteristics and structure shapes under negativeworking conditions.Firstly, through analyzing the loads of immersed tunnel, the main load conditionsaffecting on the force of immersed tunnel section joint sheer keys were found. The longitudebending working conditions causing by longitudinal uneven foundation stiffness and unevendeposit, the longitude twisting working conditions causing by transversal uneven foundationstiffness and uneven deposit were taking as the main researching working condition.Secondly, Basing on the finite element software ANSYS, adopting contact elements atsection joints, utilizing nonlinearity material to simulate rubber pads, the three dimensionaland sectional immersed tube numerical model was constructed. Through adjusting testplatform, making test models, the large scale section joint shear keys physical model similartest was carried on, which engineering scale was1:4.69.Thirdly, basing on the whole numerical simulation and indoor test, connecting with threedimensional localized shear key numerical tests, the structure measures to decrease localizedstress of shear keys were put forward. Relative study has some references to the design andresearch of other immersed tunnels. The main conclusion is that:(1)In bending working condition, vertical sheer keys have big localized stress andundertake most vertical sheering force. In twisting working condition, the stress of side wallvertical sheer keys on the softer layer is big, these shear keys have main contribution to thevertical shearing resistance.(2)In bending and twisting working condition, the localized tension stress concentrationall happened on the connection part between shear keys and immersed tunnel ling, which willbe improved by installing tension reinforcement. The localized compressive stress on tips ofshear keys is big and some structure measures can decrease the stress connection.(3)Increasing horizontal inclination of the shearing keys, the localized stress of shearkeys can be reduced in some extent and the shearing force of it increases little. Designingchamfer angle on shear key tips, it can not decrease localized stress but has larger shearingforce on shear plane. The circular design on shear key tips can decrease localized stress andshearing force both, which has advantages to the force of shear keys.