STRESS MONITORING AND SAFETY EVALUATION OF THE COUNTERFORCE FRAME DURING SHIELD ORIGINATING

Numerical simulation, real-time stress monitoring and mechanical analysis are presented for the counterforce frame used in the shield originating stage of the Wuhan Changjiang River tunnel. The function and efficacy of the frame are evaluated and a method for determining the demolition condition is discussed based on the monitoring. It is found that accidental factors, such as a sudden change of the restriction conditions, should be taken into account in the design. The demolition of the frame could be determined by in situ measurements.