Calculation of the shotcrete utilization for lining with integrated yielding elements
When dealing with tunnels in weak rock mass and with high overburden, the high displacements imposed on the lining dictate the application of ductile yielding elements with controllable stiffness and yield load. These properties are chosen with two goals in mind: the time-dependent strength of the shotcrete shell must not be exceeded; however the support pressure must be kept reasonably high and controllable. The attainable load-displacement lines of the ductile support elements are almost arbitrary. There are almost countless possible combinations of their stiffness and yield load, thus enabling the development of custom-tailored support systems and leaving considerable room for adapting to the encountered ground conditions. Tunneling in weak ground should be accompanied by increased efforts on monitoring the system behavior, best by a dense pattern of absolute displacement measurements. A simple technique for calculating the shotcrete utilization ratio has been developed. It applies a Newton- Raphson root-finding algorithm to determine the interpolation parameters while obeying the requirements of force equilibrium and fitting the measured displacements. The influence of nonsymmetrical displacement behavior caused by heterogeneity and anisotropy of the rock mass, on the lining loading can be quantified and used for support system optimization.
Nedim Radon(c)i(c) Wulf Schubert
Institute for Rock Mechanics and Tunneling, Graz University of Technology, Graz Austria
国际会议
香港
英文
1-5
2009-05-19（万方平台首次上网日期，不代表论文的发表时间）