本文選題：剪切波 + 彈性波理論�。� 參考：《重慶交通大學(xué)》2015年碩士論文

【摘要】：剪切波波速是描述土體工程性質(zhì)的一項重要指標(biāo),能很好地反映巖土的動力學(xué)特性,在工程建設(shè)中應(yīng)用廣泛。目前,測試土體剪切波速度的方法主要有兩種:原位測試法和室內(nèi)測試法。前者能獲得工程土體實際的剪切波傳播速度,但其測試成本高、操作繁雜,能考慮的條件較為單一,且試驗結(jié)果的適用范圍較窄。室內(nèi)測試法操作較為簡單,可以進(jìn)行參數(shù)化研究,并可以考慮不同的試驗條件。但該方法常會受到剪切波換能器、試樣尺寸、測試位置等因素的影響,從而難以獲得土體的真實剪切波速值,阻礙了該方法在工程中的應(yīng)用。鑒于此,本文依托于國家自然科學(xué)基金項目—基于三維波電場耦合全息成像的堤壩隱患診斷技術(shù)研究(51279219),基于發(fā)明專利—一種室內(nèi)擊實試件的橫波波速測試方法(201210075217X)和彈性波傳播理論,提出圓柱形擊實試件的剪切波傳播特性及其波速測試方法研究。本文的主要研究內(nèi)容和結(jié)論如下:(1)基于彈性波傳播理論,建立了分析彈性波在圓柱形擊實試件中傳播的三維有限元模型�；谠撃Ｐ�,分別計算了在不同加載頻率、不同加載激勵大小以及不同尺寸條件下模型中的波動。(2)基于有限元計算結(jié)果,分析了加載頻率、加載激勵大小以及模型尺寸對剪切波傳播的影響規(guī)律。結(jié)果表明,模型中的剪切波速度和波能衰減均隨著加載頻率的增大而增大,但總體來說,加載頻率對剪切波傳播的影響程度不大;瞬時激勵大小對剪切波速度基本沒有影響;直徑0.2m是剪切波速度發(fā)生明顯變化的轉(zhuǎn)折點。若超過該直徑,增大直徑對剪切波速度的影響很小;若小于該直徑,即使直徑變化很小,剪切波速度也將明顯增大,而且剪切波速度隨著直徑的改變幾乎是呈線性變化。(3)基于專利—一種室內(nèi)擊實試件的橫波波速測試方法,制作不同干密度的擊實試件并測試各試件中的剪切波速度,得到剪切波速度與干密度之間近似呈線性關(guān)系。采用超聲波檢測法測試了各擊實試件的縱波速度,得到縱波速度與干密度近似呈線性關(guān)系。根據(jù)測試結(jié)果計算了土的彈性參數(shù)并進(jìn)行了分析。(4)綜合數(shù)值模擬分析以及實測結(jié)果,對實測剪切波速度進(jìn)行了修正,并提出了修正后的剪切波速度測試方法。
[Abstract]:Shear wave velocity is an important index to describe the engineering properties of soil, which can well reflect the dynamic characteristics of rock and soil, and is widely used in engineering construction. At present, there are two main methods for measuring the shear wave velocity of soil: in situ and in-house. The former can obtain the actual shear wave propagation velocity of engineering soil, but its testing cost is high, the operation is complicated, the conditions can be considered are relatively simple, and the application range of the test results is relatively narrow. The indoor test method is easy to operate and can be parameterized and different test conditions can be considered. However, the method is often affected by the shear wave transducer, sample size, testing position and other factors, so it is difficult to obtain the true shear wave velocity of soil, which hinders the application of the method in engineering. In view of this, This paper is based on the project of National Natural Science Foundation of China-based on 3D wave electric field coupled holographic imaging, the research on hidden hazard diagnosis technology of embankment and dam. Based on the invention patent, a method of measuring the velocity of shear wave and elastic wave propagation theory. The characteristics of shear wave propagation and the measurement method of wave velocity of cylindrical compacted specimens are presented. The main contents and conclusions of this paper are as follows: (1) based on the theory of elastic wave propagation, a three-dimensional finite element model is established to analyze the propagation of elastic wave in cylindrical compacted specimens. Based on the model, the fluctuation of the model under different loading frequency, different load excitation size and different size is calculated, and the loading frequency is analyzed based on the results of finite element calculation. The effect of loading excitation and model size on shear wave propagation. The results show that the shear wave velocity and wave energy decay in the model increase with the increase of loading frequency, but in general, the influence of loading frequency on shear wave propagation is not significant, but the instantaneous excitation has no effect on shear wave velocity. The diameter of 0.2m is the turning point when the velocity of shear wave changes obviously. If the diameter exceeds the diameter, the increase of the diameter has little effect on the velocity of the shear wave, and if the diameter is smaller than the diameter, the velocity of the shear wave will increase obviously even if the diameter changes very little. And the shear wave velocity is almost linearly varying with the diameter.) based on the patent, a method for measuring the shear wave velocity of the compacted specimens in laboratory, we make the compacted specimens with different dry densities and test the shear wave velocities in each specimen. The approximate linear relationship between shear wave velocity and dry density is obtained. The longitudinal wave velocities of the compacted specimens were measured by ultrasonic method, and the linear relationship between the longitudinal wave velocities and dry density was obtained. According to the test results, the elastic parameters of the soil are calculated and analyzed. 4) the numerical simulation analysis and the measured results are carried out. The measured shear wave velocity is corrected and the modified shear wave velocity measurement method is put forward.
【學(xué)位授予單位】：重慶交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TU411

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本文編號：1999951