【摘要】：在抗震研究領(lǐng)域,土層的剪切波速值的大小不僅能夠反映場地傳播地震波能力的大小,同時它也是描述土體動力特性的一個重要參數(shù)。在工程中,常用剪切波速來確定土層覆蓋層厚度,判別砂土或粉土地基的地震液化、建筑場地類別,計算土體的動剪切模量等。因此,對剪切波速研究有實際的工程意義和理論價值。對于土這種復(fù)雜的地質(zhì)體,由于結(jié)構(gòu)、成因、形成歷史和成分的不同,使得剪切波速在不同的土層和不同的條件下都表現(xiàn)出很大的差異。目前國內(nèi)外對于剪切波的測試,一方面由于測試的手段和測試條件的限制,使獲得土層剪切波速的資料增加了困難或測試的不夠理想;另一方面在獲取剪切波速測試數(shù)據(jù)后,為了計算的簡便對其采用了很多的近似處理,這些都給剪切波速的測試帶來了一定的誤差。因此,本文就獲得剪切波速資料后,如何既方便簡單又能保證精度的前提下計算出土層的剪切波速值進行研究。本文圍繞土層剪切波速資料開展了如下工作。1、對目前剪切波速測試的問題進行了詳細(xì)的闡述,分析了CT(Computerized Tomography計算機層析成像)技術(shù)在處理剪切波速資料方面的應(yīng)用,并對CT技術(shù)的內(nèi)容、發(fā)展以及在地球物理領(lǐng)域的應(yīng)用進行了簡單的介紹。2、詳細(xì)介紹了我國工程界廣泛使用的土層剪切波速測試的各種儀器的原理和使用方法。對各種儀器的適用范圍、各種測試方法和資料整理分析的方法進行了對比分析,指出了各自的優(yōu)缺點,并選擇將CT技術(shù)運用于目前運用最多最方便的單孔法測試中。3、詳細(xì)的介紹了CT技術(shù)中的理論知識:地球物理反演理論。主要介紹了反演理論的概念,數(shù)學(xué)物理模型以及反演問題解的特性,并著重介紹了地震波速度反演技術(shù)(CT)的研究進展和求解方法。4、分析運用走時反演成像理論,模擬單孔測試的方法,假設(shè)波從激發(fā)點激發(fā)到接收點接收是沿直線傳播的,詳細(xì)的介紹了單孔CT技術(shù)的基本原理,同時詳細(xì)的介紹了如何在MATLAB中實現(xiàn)這樣的傳播模型。5、介紹了反演算法的基本原理,并詳細(xì)的介紹了運用聯(lián)合迭代法(SIRT)求解走時反演問題的具體過程,以及在MATLAB環(huán)境中實現(xiàn)這樣過程的具體步驟。6、以蕪湖市某工程為例,選取了場地的兩個鉆孔的單孔測試資料進行反演計算,并將反演結(jié)果與單孔法測試的傳統(tǒng)計算方法進行對比分析,證明了上述直線路徑反演算法的正確性和可行性,同時對于其不足之處和尚需改進的方面也作了說明。
[Abstract]:In the field of seismic research, the value of shear wave velocities of soil layer can not only reflect the magnitude of seismic wave propagation capacity, but also is an important parameter to describe the dynamic characteristics of soil. In engineering, shear wave velocity is commonly used to determine the thickness of soil cover, to distinguish the seismic liquefaction of sand or silt foundation, to classify the building site, and to calculate the dynamic shear modulus of soil. Therefore, the study of shear wave velocity has practical engineering significance and theoretical value. For a complex geological body such as soil, due to the difference in structure, origin, formation history and composition, shear wave velocities show great differences in different soil layers and different conditions. At present, the testing of shear wave at home and abroad, on the one hand, because of the limitation of testing means and testing conditions, makes it more difficult to obtain the data of shear wave velocity of soil layer or is not good enough for testing; on the other hand, after obtaining the data of shear wave velocity measurement, For the sake of simplicity of calculation, many approximate treatments are used, which bring some errors to the measurement of shear wave velocity. Therefore, after obtaining the shear wave velocity data, how to calculate the shear wave velocity of soil layer on the premise of convenience, simplicity and accuracy is studied in this paper. In this paper, the following work has been done around the soil shear wave velocity data: 1. The current problems of shear wave velocity measurement are described in detail, and the application of CT (Computerized Tomography computer tomography technology in the processing of shear wave velocity data is analyzed. The content, development and application of CT technology in geophysics are briefly introduced. The principle and method of various instruments for measuring shear wave velocity of soil layer widely used in engineering field in China are introduced in detail. The scope of application of various instruments, various testing methods and methods of data arrangement and analysis are compared and analyzed, and their respective advantages and disadvantages are pointed out. And choose to use CT technology in the most convenient single hole method test at present. It introduces the theory knowledge of CT technology in detail: geophysical inversion theory. This paper mainly introduces the concept of inversion theory, mathematical and physical model and the characteristics of inversion problem solution, and emphatically introduces the research progress and solution method of seismic wave velocity inversion technique (CT), and analyzes the application of traveling time inversion imaging theory. The method of simulating the single hole test assumes that the wave propagates along a straight line from the excitation point to the receiving point. The basic principle of the single hole CT technique is introduced in detail. At the same time, it introduces in detail how to realize this propagation model in MATLAB, introduces the basic principle of inversion algorithm, and introduces in detail the concrete process of solving the traveling time inversion problem by using joint iteration method (SIRT). Taking a project in Wuhu City as an example, the single hole test data of two boreholes in the site are selected for inversion calculation. The inversion results are compared with the traditional calculation method tested by the single hole method, which proves the correctness and feasibility of the above algorithm. At the same time, the inadequacies of the algorithm and the aspects that need to be improved are also explained.
【學(xué)位授予單位】：安徽建筑大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TU435

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本文編號：2253477