The Evaluation and Prediction for Rockfall Hazard and Risk
|Keywords:||落石;危險度;危害度;可靠度;安全餘額;中部橫貫公路;Rockfall;Hazard;Risk;Reliability;Safety Margin;central cross-ridge route|
Rockfall often occurs along mountainside road slopes, especially during or after a heavy rainfall. Occasionally, the occurrence of a rockfall results in traffic interruption, property damage, and personal injury or death. The consequence of a rockfall incidence may be very serious and unacceptable for a community. The hazard potential of a rockfall depends on various factors including geology, topography, and weather, among many environmental factors. In the conventional approach, the hazard potential of rockfall is usually evaluated in a deterministic manner. Compared to other aspects of geotechnical engineering, the rockfall problem has a higher degree of uncertainty. It seems reasonable to take the probabilistic nature of rockfall problem into account. This thesis makes use of reliability analysis to investigate the probability of rockfall hazard. It also examines the influence of rainfall on hazard potential. By collecting relevant information concerning the factors that affect the rockfall hazard, this thesis attempts to establish a probabilistic model for evaluating rockfall hazard associated with the condition of rainfall. It establishes an empirical correlation between the minimum rockfall hazard rating and rainfall characteristics (including the cumulative rainfall and the daily rainfall at the time of rockfall). The probability of rockfall is calculated from the safety margin (the difference between the threshold index and the rockfall potential index). The threshold index is assumed normally distributed; it is calibrated from real rockfall records using an optimization procedure. The proposed approach is applied in evaluating the rockfall hazard along the central cross-ridge route. The comparison of the predicted results and the actual case records shows very good agreement. In addition, this thesis adopts the concept of risk analysis and suggests an approach to evaluate the potential for traffic interruption, human life loss and property damage due to a rockfall occurrence.
|Appears in Collections:||Thesis|