1.Introduction 1.3 Design Principle Principle 3 Instrumentation of pilot excavations and main tunnel for displacements,loads and stresses Principle 3.1 Evaluate the stand-up time Principle 3.2 Select the most appropriate excavation method,support type and installation time Principle 3.3 Design the final tunnel support Monitoring of the tunnel behaviour Evaluate safety of the final structure 百年同濟77 Principle 3 Instrumentation of pilot excavations and main tunnel for displacements, loads and stresses Principle 3.1 Evaluate the stand-up time Principle 3.2 Select the most appropriate excavation method, support type and installation time Principle 3.3 Design the final tunnel support Monitoring of the tunnel behaviour Evaluate safety of the final structure 1. Introduction 1.3 Design Principle