Advance Rate Simulation for Hard Rock TBMs

摘要

The existing methods for estimating the advance rate of hard rock Tunnel Boring Machine (TBM) often involves estimation of the machine utilization in a direct or an indirect manner. These methods are based on empirical systems and are limited in their capacity for incorporating new machine capabilities or including many of the geological features along the tunnel. As such, these models are not used as often due to their shortcomings. The objective of this study is to offer some improvements by using a new approach for simulating all activities. The basic idea in simulation techniques is to predict the duration of different activities based on their recorded time distributions from past case histories or from the early stages of a project. A simulation model contains a series of operations, which should be repeated for a certain number of cycles. In each cycle, the model selects an anticipated duration time from time distribution curves for each activity and by using a logical relationship between activities, being parallel or in series and the possibility of activity overlaps, it assigns a duration for the whole cycle. This is then continued to finish the task at hand with required number of cycles. In this case, the cycles are the TBM going through each stroke or penetration cycle. This study includes discussion of each activity or failure of each subsystem and assigned and related duration accounts for parallel activities, and offers a distribution of cycle time, and finally estimation of tunnel completion time. A comprehensive study was conducted to evaluate the requirements for California switch final location and also the work arrangements for locomotives and trains for different scenarios. Different arrangements were programmed with Arena0 simulation software using field data of a double shield TBM, which recently completed a water conveyance tunnel. The simulation results show a very good agreement with the actual values of TBM advance rate values and also show the possible variation of the time required for completion of different sections of this tunnel. The outcome of this study was to establish a framework for arranging and modeling the main time components of TBM operation. This will provide a useful tool for developing reliable estimates of machine advance rate for specific site, ground condition, and machine type.