本文選題：無量綱 + 二維有限元方法�。� 參考：《中國地震局工程力學(xué)研究所》2015年碩士論文

【摘要】：盆地、局部不規(guī)則地形和地下夾雜等復(fù)雜場地對地震動有顯著影響,建筑的選址和抗震設(shè)防越來越重視復(fù)雜場地的放大效應(yīng)。本文研究了二維SH波入射下,地下圓形夾雜以及典型的凹陷和凸起地形對地震動的影響,結(jié)合蘆山地震強震記錄分析了局部不規(guī)則地形的影響。具體研究工作包括:1.引入了模型的無量綱參數(shù),并通過數(shù)值計算驗證了模型無量綱化的可行性。2.利用二維有限元方法和譜比法從時域和頻域分析研究空穴、軟弱和堅硬夾雜對地震動的影響規(guī)律。研究表明:軟弱夾雜和空穴對地表地震動有較大放大作用,且放大的規(guī)律較為相近,在地表的放大位置也相同,其中軟弱夾雜對入射波頻率更敏感,對地表放大倍數(shù)更大;堅硬夾雜主要表現(xiàn)為屏障作用,對地表放大作用較小,其影響幾乎可以忽略。3.利用二維有限元方法和譜比法從時域和頻域研究凹陷和凸起地形在垂直和斜入射下對地面運動的影響規(guī)律,并分析了凹陷和凸起地形隨深寬比和高寬比的變化對地面運動影響的變化規(guī)律。研究表明:凹陷地形對地形上的點放大相對較小,對附近地平面的點放大較大,斜入射時在迎波面一側(cè)角點位置放大最大,隨著凹陷地形深寬比的增大,地形的放大作用增大;凸起地形則對地形上的點放大較大,對附近地平面的點放大較小,斜入射情況下,凸起地形上入射波能直達的區(qū)域受到的最大放大作用最大,迎波面地平面的最大放大作用次之,背波面地平面和地形上的影區(qū)以及角點的放大作用相對較小,垂直入射情況下,凸起地形的頂點放大最大,隨著凸起地形高寬比的增大,凸起地形頂點受到的放大作用增大,其余點的放大作用先增大后減小。4.結(jié)合蘆山地震主震以及41次余震在4個地形不同的相鄰臺站的強震記錄,采用傳統(tǒng)譜比法(RSM)和水平分量與垂直分量譜比法(HVSR)分析地形的影響。研究表明:4個臺站受地形的影響都有較大的放大作用;余震記錄分析表明處于山腰的51BXZ臺放大作用大于處于山腳的51BXD臺,51BXZ臺在3Hz左右有很明顯的放大,在8-14Hz也有一定的放大,51BXD臺則在5-10Hz范圍都有相對較小的放大;主震在51BXZ臺記錄的幅值小于51BXD臺的原因可能是受限于震級較大時土層非線性的影響。
[Abstract]:Complex sites, such as basins, local irregular topography and underground inclusions, have a significant impact on ground motion. The site selection and seismic fortification of buildings pay more and more attention to the amplification effect of complex sites. In this paper, the effects of underground circular inclusions and typical depression and uplift topography on ground motion under the incidence of 2-D SH wave are studied. The influence of local irregular topography is analyzed based on the strong earthquake records of the Lushan earthquake. Specific research work includes: 1. The dimensionless parameters of the model are introduced, and the feasibility of dimensionless model is verified by numerical calculation. Two dimensional finite element method and spectral ratio method are used to study the influence of holes, weak and hard inclusions on ground motion in time and frequency domain. The results show that the weak inclusions and holes have larger magnification effect on the ground motion, and the law of magnification is similar, and the magnifying position of the weak inclusions is also the same. The weak inclusions are more sensitive to the frequency of incident waves and more magnified to the surface. The hard inclusion is mainly a barrier effect, but it has little effect on the surface magnification, and its influence can be almost ignored. 3. Using the two-dimensional finite element method and spectral ratio method, the effects of depression and uplift topography on ground motion under vertical and oblique incidence are studied in time and frequency domain. The influence of the depth to width ratio and the aspect ratio on the ground motion is analyzed. The results show that the point magnification is relatively small in the sag terrain and larger in the nearby ground plane, and the angle position at the side of the wave face is the largest when oblique incidence occurs. With the increase of the ratio of depth to width of the depression terrain, the magnification effect of the topography increases. On the other hand, the point magnified by the raised terrain is larger than that by the ground plane nearby. The maximum magnification of the area with direct incident wave energy on the convex terrain is the largest in the case of oblique incidence. The maximum magnification of the ground plane is the second, and the magnification of the shadow area and the corner point on the back wave plane and terrain is relatively small. In the case of vertical incidence, the maximum magnification of the vertex of the raised terrain is obtained, and with the increase of the aspect ratio of the raised terrain, The magnification of the topographic vertices is increased, and the magnification of the other points increases first and then decreases. 4. Combined with the strong seismic records of the Lushan earthquake main shock and 41 aftershocks in four adjacent stations with different topography, the influence of topography was analyzed by using the traditional spectral ratio method (RSM) and the horizontal and vertical component spectral ratio method (HVSRs). The results show that the four stations are greatly magnified by the topography, and the aftershock records show that the magnification effect of the 51BXZ station at the mountainside is larger than that of the 51BXD station 51BXZ at the foot of the mountain. The amplitude of the main shock recorded in the 51BXZ station is smaller than that of the 51BXD station, which may be due to the nonlinear effect of the soil layer when the magnitude of the main shock is larger than that of the 51BXD station.
【學(xué)位授予單位】：中國地震局工程力學(xué)研究所
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：P315.9

【參考文獻】

相關(guān)期刊論文 前3條

1 廖振鵬;楊柏坡;袁一凡;;三維地形對地震地面運動的影響[J];地震工程與工程振動;1981年01期

2 梁建文,張浩,Vincent WLee;地下洞室群對地面運動的影響[J];土木工程學(xué)報;2005年02期

3 曹欣榮,宋天舒,劉殿魁;任意形狀凸起地形對平面SH波的散射[J];應(yīng)用數(shù)學(xué)和力學(xué);2001年09期

，

本文編號：1796286