مجله ژئوفیزیک ایران

مجله ژئوفیزیک ایران

بررسی اثر لایه‌بندی خاک بر بزرگنمایی تپه‌های متناوب نیم‌دایره‌ای و ذوزنقه‌ای

نوع مقاله : مقاله پژوهشی‌

نویسندگان
1 استادیار گروه مهندسی عمران، دانشکده فنی و مهندسی، دانشگاه صنعتی قم، قم، ایرانن
2 دانش‌آموخته کارشناسی ارشد گروه مهندسی عمران، دانشکده فنی و مهندسی، دانشگاه صنعتی قم، قم، ایران
چکیده
امروزه کاملاً آشکار است که ناهمواری‌های سطحی به‌دلیل تأثیرات زیادی که بر پاسخ لرزه‌ای ساختگاه‌ها دارند، باید در محاسبات لرزه‌ای مورد توجه قرار گیرند. در این مقاله، اثر توأم زاویه شیب لایه‌های مصالح تپه و ارتفاع در توپوگرافی‌های متناوب، تحت تأثیر زلزله‌های لاندرز و نورثریج برای دو هندسه تپه نیم‌دایره ای و ذوزنقه‌ای به کمک روش تفاضل محدود ارائه شده‌است. به‌دلیل برهم‌کنش دینامیکی بین تپه‌ها، دامنه‌های جابه‌جایی توپوگرافی متناوب بزرگتر از دامنه‌های توپوگرافی تک هستند. به‌عنوان مثال، تپه تکی با ارتفاع ۳۰ متر دارای بزرگنمایی تقریباً ۷۹/۱ در زاویه ۱۵ درجه است. در حالی‌که در همین ارتفاع و زاویه، تپه نیم دایره‌ای سه‌تایی، بزرگنمایی ۹۷/۱ را تجربه کرده‌است. در ادامه، تأثیر چگالی، مدول الاستیسیته و نسبت پوآسون مصالح بر روی بزرگنمایی حرکت لرزه‌ای تپه‌های با مصالح لایه‌ای غیر افقی بررسی شده ‌است. با افزایش چگالی و نسبت پوآسون، به‌تنهایی، بزرگنمایی لرزه‌ای افزایش یافته اما تغییر در مقدار مدول الاستیسیته، به‌تنهایی، بر روی بزرگنمایی اثر ندارد. در مورد نسبت پواسون در زوایای مختلف بررسی شده باید اذعان نمود که در تمامی زوایا، یک بزرگنمایی مشاهده شده است، به‌عبارت دیگر، اثر تغییرات زاویه زمانی که نسبت پواسون مورد بررسی قرار گرفته است، نتایج یکسانی بدست آمده است.
کلیدواژه‌ها

موضوعات


عنوان مقاله English

Effect of soil layering on resonance of alternating semi-circle and trapezoidal Hills

نویسندگان English

Masoud Amelsakhi 1
Ayda Haraty 2
1 Assistant Professor, Department of Civil Engineering, Faculty of Engineering, Qom University of Technology, Qom, Iran
2 دM.Sc. Student in Civil Engineering, Faculty of Engineering, Qom University of Technology, Qom, Iran
چکیده English

It is obvious that surface roughness should be considered in seismic calculations due to their many effects on seismic response of sites. In this paper, the combined effect of slope angle of hill material layers and height in alternating topography under the influence of Landers earthquake for two geometry of semi-circle and trapezoidal hills is using finite difference method is presented. Due to dynamic interaction between the hills, alternating topographic displacement is larger than single topography. For example, a single hill with a height of 30 meters has an amplification of approximately 1.79 at an angle of 15 degrees while at the same height and angle, the triple sine hill has experienced an amplification of 1.97. Then, the effect of density, elasticity modulus and Poisson ratio of materials on seismic motion of hills with non-horizontal layered materials is investigated. With increasing density and Poisson ratio, alone, seismic amplification increased but changes in the amount of elasticity modulus alone did not affect the magnification. Differences in layering due to Poison Ratio had negligible effect on amplification. The hill’s height is an important parameter that effects on amplification responses. As height increases, the amplification increases too. Another important parameters are number of adjacent hills, height of adjacent hill and also the distance between the hills. The more height hill adjacent to the base hill, the more amplification for the base hill. The obtained results demonstrate that as the height of the hill increases, the effect of different angles of layering increases on amplification of the base hill. It means that although the hill’s height is an important parameter, but also this parameter directly increases the effect of the angle between layers of the hill on amplification and seismic response of the hill. It is very important to consider these effects for design the structures located on these hills. Another important parameter that is studied in this research is the mass density of the hill’s material. The mass density has an increasing effect on seismic response of the hill; as the mass density of the hill material increases, the amplification increases. This means that as the weight of the hill increases, the amplification increases; as it is also an important matter in seismic behavior of different buildings in seismic codes. Obtained results show that elasticity modulus of the soil does not have any important effect when the angle between the soil layers are investigated.

کلیدواژه‌ها English

Alternating topography
soil Layering
topography height
seismic response
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