پژوهشگاه بین المللی زلزله شناسی و مهندسی زلزله فصلنامه علوم و مهندسی زلزله 2476-6097 13 2 2026 06 22 Numerical Study of the Effect of Layering Thickness and Angle on the Amplification of the Two-layered Semi-Sine Hill بررسی عددی اثر ضخامت و زاویه لایه‌بندی در بزرگنمایی تپه نیم سینوسی دولایه 33 17 725152 10.48303/bese.2025.2048723.1214 FA محمد حسین ناطقی دانش‌آموخته کارشناسی ارشد، گروه مهندسی عمران، دانشگاه صنعتی قم، قم، ایران مسعود عامل سخی استادیار گروه مهندسی عمران، دانشکده فنی و مهندسی، دانشگاه صنعتی قم، قم، ایران 0000-0002-5894-0404 Journal Article 2024 12 23 When seismic waves travel from the bedrock into the soil layers, resonance occurs. Generally, the concept of resonance means that the level of damage to surface structures increases. The closer the characteristics of the soil layers are to each other, the less resonance occurs; conversely, the more different these layers are from one another, the greater the resonance. Therefore, the presence of soft soil over bedrock causes the amplified acceleration to be transferred to the foundation of the structure, increasing the likelihood of damage to the structure. Topographic amplification refers to the phenomenon where seismic waves are enhanced or altered as they interact with the topography of a site, such as hills, valleys, and ridges. This amplification can significantly influence the seismic response of structures, leading to increased ground motion and potentially greater damage during an earthquake. Investigating topographic amplification and its effects on the seismic response of topographic sites is an important issue that has attracted considerable interest from many researchers. Studies in the area of topographical influences have shown that the nature of the terrain is instrumental in influencing the level of damage caused by earthquakes. Local topographical formations can enhance intense ground movements during earthquakes, resulting in significant damage. Iran is located in a seismically active region, with many areas in the country adjacent to various topographies, especially hills. Given the presence of active faults in the country and a history of significant earthquakes, it is essential that the design and construction of structures are carried out in a way that provides sufficient resistance to these influential factors. Studies and research conducted on the effects of topography and the phenomenon of seismic wave amplification as they pass through surface layers have shown that topography has a considerable impact on the extent of earthquake damage. In this research, the hill model in the form of a semi-sinusoidal shape is examined in two layers, as well as the effects of this type of site on the amplification of ground response. By modeling several semi-sine hills with different stratifications using FLAC software under Rayleigh wave conditions, the impact of topography is investigated. Before conducting the modeling, the accuracy of the analytical method must be verified. For this purpose, validation studies from Wang (1982) and results from other researchers will be used to authenticate the analysis of two problems. Finally, to ensure the accuracy of the FLAC software, a similar model will be constructed, and by applying a Rayleigh wave, the desired parameters will be determined at various points of the site (semi-sinusoidal hills) and compared with the graphs from the article. This research examines how a frequently found topographical feature, particularly semi-sinusoidal hills, influences the seismic reaction of the Earth's surface when exposed to vertically propagating SV waves. The main objective of this research is to examine the effects of various layering at a specific type of site, namely semi-sinuous hills. The study aims to model and analyze the seismic response of this type of site, investigating the impact of surface topography on seismic behavior and comparing the results obtained from the analysis under different conditions. In this research, efforts have been made to investigate the seismic behavior of sinuous hills under different layering conditions to determine the effects of soil characteristics in the layers, as well as the thickness and angle of the layers on the results obtained. This study investigated how layering affects the response of semi-sinusoidal hills by analyzing hills with two layers, each featuring different layering characteristics and thicknesses. The study also examines the impact of soil characteristics, layering thickness and angle and the position of the looser layer. Different features in layering have an impact on the overall trend of amplification on the top of hills and de-amplification near the toes of hills in response to the horizontal components of displacement, velocity, and acceleration. The study revealed that in two-layer hills, the effects of soil characteristics are greater compared to the thickness and angle of layering. Overall, the most significant change in the acceleration component was observed when the upper layer was loosened in two-layer hills. Conversely, the smallest change in all three components occurred when the upper layer was halved. اثر توپوگرافی بر پاسخ لرزه‌ای، مسئله‌ای چالش‌برانگیز در ژئوتکنیک لرزه‌ای است که پیچیدگی آن با وجود لایه‌های مختلف در تپه و زاویه‌ها و مشخصات متفاوت لایه‌بندی نسبت به یکدیگر افزایش می‌یابد. این پژوهش به بررسی عددی تأثیر توپوگرافی بر پاسخ لرزه‌ای تپه‌ای دولایه با مشخصات، ضخامت و زاویه‌ی لایه‌بندی متغیر می‌پردازد. تاکنون، تأثیر توأمان این پارامترها در تپه‌های غیرهمگن کمتر مورد توجه قرار گرفته است. با استفاده از روش تفاضل محدود، مدل‌های عددی متعددی از تپه با دولایه با مشخصات مختلف ایجاد و تحلیل شدند. ضخامت هر لایه، زاویه‌ی لایه‌بندی و موقعیت لایه‌ی سست به‌عنوان پارامترهای اصلی در نظر گرفته شده و اثر آنها بر بزرگ‌نمایی سه مؤلفه‌ی شتاب، سرعت و جابه‌جایی بررسی گردید. نتایج نشان می‌دهد که تغییرات در مشخصات مصالح لایه‌ها (به‌ویژه سست‌تر شدن لایه‌ی بالایی) تأثیر بسیار قابل توجهی بر بزرگ‌نمایی دارد، به‌مراتب بیشتر از آنچه از تغییر در ضخامت یا زاویه‌ی لایه‌بندی حاصل گردید. کمترین تغییر در مؤلفه‌های پاسخ به هنگام نصف شدن ضخامت لایه‌ی بالایی مشاهده شد. علاوه بر این، موقعیت لایه‌ی سست نیز به‌طور معنی‌داری بر پاسخ لرزه‌ای تپه اثر می‌گذارد. این یافته‌ها اهمیت در نظر گرفتن خصوصیات لایه‌بندی و مشخصات مصالح در ارزیابی دقیق پاسخ لرزه‌ای تپه‌ها را به‌روشنی نشان می‌دهد و برای بهبود تحلیل‌های خطر زلزله در مناطق تپه‌ای اهمیت دارد. این پژوهش نقش تعیین کننده‌ی مشخصات مصالح نسبت به هندسه در پاسخ لرزه‌ای تپه‌ها را آشکار می‌کند و می‌تواند به ارائه‌ی مدل‌های دقیق‌تر برای طراحی لرزه‌ای در مناطق تپه‌ای منجر شود.

https://www.bese.ir/article_725152_3722ca86216c108ef2f143090f5c10e8.pdf