Calculation Models and Dynamic Design for Inverted Arch of Shallow Mountain Tunnels

For lack of calculation theory,the design of inverted arch in some tunnels is not reasonable,especially in shallow tunnels.With a load coefficient,the relation between the upward press from the soft rock and the load on the inverted arch is built up.Considering the construction technology,a mechanics model of three-hinged-arch is built,and the equation of reasonable axial line and formula for internal force of inverted arch are given.In addition,a calculation example is offered to account for the design method,which can be consulted by application.Considering the actual geological conditions may differ from the survey and design,the dynamic design adopted in inverted arch design is suggested in order to achieve a reliable and reasonable design.