大宁河特大拱桥拱座-基岩长期稳定性研究

Long-term stability of arch support and bedrock of Daning River Bridge

大宁河特大拱桥巫山端拱座建造在弱风化溶崩角砾岩基岩上,拱座–基岩的长期稳定性是桥梁安全运营的关键。依据弱风化溶崩角砾岩蠕变试验得到的幂函数形式蠕变方程,建立了三维拱座–基岩接触面有限元模型,通过数值仿真研究了桥梁长期运营过程中弱风化溶崩角砾岩基岩的应力特征、变形特征、拱座的应力分布变化规律、拱座–基岩接触面剪切应力分布及张开度变化等特性,研究成果表明:①基岩长期蠕变导致应力调整,拱座抗推桩会出现拉应力集中;②长期蠕变过程中拱座–基岩协调变形,接触面张开度很小,拱座–基岩接触面上顺桥向剪切应力也较小。研究成果对于拱座设计、拱座–基岩长期稳定评价具有指导意义。

The arch support at Wushan end of Daning River Bridge is constructed on weathered solution-collapse breccias,which is soft and prone to creep.Evaluation of long-term stability of arch support and breccias is of great importance for the security of service of Daning River Bridge.Based on the laboratory creep test results of weathered solution-collapse breccias,a creep constitutive model is established and the parameters are proposed.Using the creep model,the long-term evolution of stress and deformation of the arch support and breccias is analyzed by means of the 3D finite element method（FEM）.The openings and shear stress between the contact surface of arch support and breccias are studied.Numerical results show that：（1） the creep of breccias can cause local tensile stress concentration on thrust resistance piles;（2） the arch support and bedrock show compatible deformation during long-term creep,and the opening of the contact surface is very small.In addition,the shear stress in most part of the contact surface is less than 0.1 MPa.This study may be helpful for the design of arch support and long-term maintenance of the slope.