Hindawi Publishing Corporation Mathematical Problems in Engineering Volume 2013, Article ID 653282, 10 pages http://dx.doi.org/10.1155/2013/653282 Research Article Rainfall Reliability Evaluation for Stability of Municipal Solid Waste Landfills on Slope Fu-Kuo Huang, 1 Grace S. Wang, 2 and Yueh-Lin Tsai 3 1 Department of Water Resources and Environmental Engineering, Tamkang University, New Taipei City 25137, Taiwan 2 Department of Construction Engineering, Chaoyang University of Technology, Taichung City 41349, Taiwan 3 Project Department, GeoTech Science Corporation Ltd., New Taipei City 22103, Taiwan Correspondence should be addressed to Fu-Kuo Huang; fhuang@mail.tku.edu.tw Received 5 November 2012; Revised 12 February 2013; Accepted 28 February 2013 Academic Editor: Sunghwan Kim Copyright © 2013 Fu-Kuo Huang et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. A method to assess the reliability for the stability of municipal solid waste (MSW) landflls on slope due to rainfall infltration is pro- posed. Parameter studies are frst done to explore the infuence of factors on the stability of MSW. Tese factors include rainfall inten- sity, duration, pattern, and the engineering properties of MSW. Ten 100 diferent combinations of parameters are generated and associated stability analyses of MSW on slope are performed assuming that each parameter is uniform distributed around its reason ranges. In the following, the performance of the stability of MSW is interpreted by the artifcial neural network (ANN) trained and verifed based on the aforementioned 100 analysis results. Te reliability for the stability of MSW landflls on slope is then evaluated and explored for diferent rainfall parameters by the ANN model with frst-order reliability method (FORM) and Monte Carlo simulation (MCS). 1. Introduction Te response of municipal solid waste (MSW) landflls during earthquakes has gained much attention during the past years (Anderson and Kavazanjian [1], Anderson [2], Augello et al. [3], Idriss et al. [4], Kavazanjian and Matasovic [5], Kavazan- jian et al. [6], Krinitzsky et al. [7], and Pinto [8]). However, there were many failure events of MSW landflls on slope resulted from rainfall situations (Huvaj-Sarihan and Stark [9], Liu [10]). Tus, the stability of MSW landflls on slope due to rainfall infltration is another important topic worthy of further studied. As to stability evaluation of MSW landflls on slope, safety factors are common used in engineering practice. Te critical state of failure is usually regarded as reached when the factor of safety, FS, is equal to 1.0 based on this approach. Tis deterministic approach not only does not consider the infu- ence of randomness and uncertainties of soil properties, anal- ysis model, and associated parameters on the analysis results but also has not any implications about the failure probability of the critical state according to the factor of safety. In other words, factors of safety are usually selected based on past experience empirically. Te relationship between the factor of safety and the probability of failure is ofen unclear and needs to be established. If uncertainties of associated analysis parameters are greater than anticipated, an unstable situation of the MSW landflls may be encountered by using the deter- ministic factor-of-safety approach. Conversely, overdesign- ing can probably be done to some extent when uncertainties are smaller than anticipated. Accordingly, the reliability- based design (RBD) or performance-based design (PBD) approach that can evaluate the ultimate or serviceability per- formance of the MSW landflls on slope probabilistically is preferred in landfll and slope engineering. Te researches of reliability in geotechnical engineering are growing rapidly in these years. H. D. Lin and C. P. Lin [11] applied it to drilled piles while Shou and Chen [12] to spatial risk analysis of landslide. For deep excavation, Tang et al. [13] frst performed a reliability analysis and design of braced excavation systems with FOSM method. Low [14] adopted FORM and MCS method by spreadsheet to reliability-based design for retaining walls using explicit