NUMERICAL ANALYSIS OF CONSTRUCTION DYNAMIC BEHAVIOR OF PARALLEL TUNNEL OF HIGHWAY WITH LARGE SECTION AND SMALL CLEAR-DISTANCE

Based on large section and small clear-distance tunnel engineering characteristics, the tunnel project is using per twin-side heading method.In order to obtain the dynamic variation law of tunnel excavation, the numerical model is established with the finite element software ADINA as calculation platform. The distribution characteristics and variation laws of the ground settlement, the displacement and internal force of the lining, the bolt axial forces, the pressure distribution and change rule of surrounding rock and initial support structure are all studied.The numerical results show that the upper surface horizontal and vertical displacement of the first excavation tunnel is larger than the later one.The stress concentrates from the arch lumbar to the foot of the tunnel structure;the maximum principal stress and effective stress of the first excavation tunnel are larger than the later one;the system anchoring bolt axial force is not only concentrating on the arch lumbar and foot, but became much smaller along its radiation;the system supporting of the first excavation tunnel can stable the rock mass, but the later one has a disturbance action to the first one and the surrounding rock mass.The study results are drawn to provide the basis for modifying and optimizing the design and construction scheme.Simultaneously, this will offer some useful references for the design and construction of tunnels in the similar geological condition.