【作者】 杨喆；

【导师】 王家鼎；

【作者基本信息】 西北大学 ， 地质工程， 2008， 硕士

【摘要】 近年来,随着高速铁路的大量兴建,列车运行速度的提高和牵引重量的增加将不可避免地增大列车振动强度,列车运行对边坡的变形稳定性所产生的振动影响越来越受到工程地质界的关注。本文以铁路沿线黄土滑坡及其滑带土为研究对象,通过现场勘察、室内试验、力学分析、理论研究和数值计算相结合的方法,对高速列车振动荷载作用下黄土滑坡滑带土的动力特性及其边坡的变形稳定性进行了较为深入系统的研究,并取得了一些较有价值的研究成果,主要包括:(1)对机车振动作用下黄土滑坡的形成条件和特征进行了深入剖析,认为机车振动也是促发黄土滑坡的一个主要因素;并对黄土滑坡滑带土的特征进行了简单总结,为滑带土室内试验奠定了理论基础。(2)选择典型地段,采集大量滑带土样品,在动三轴上通过对试样施加不同围压和不同动应力,研究其在模拟机车振动荷载作用下土的动强度及动变形的变化规律。结果表明,滑带黄土在一定的动应力条件下,其动强度和累积残余应变随着振次、固结应力的变化,呈现一定的规律性变化。(3)利用本次试验数据,将BP神经网络的方法和多元线形回归的方法应用于滑带黄土振陷系数的预测中,并将结果进行了比较,结果表明,BP神经网络的方法在预测振陷系数上优于多元线形回归法。(4)利用数值模拟软件FLAC对高速列车振动荷载作用下黄土边坡的变形稳定性进行了分析。结果表明列车运行速度对黄土边坡的扰动程度及边坡稳定性系数的影响呈一定的规律性变化。为高速铁路黄土边坡的设计和加固提供了理论依据。(5)对黄土滑坡机理进行了研究,提出列车在小振幅、长持时振动荷载作用下黄土滑坡的形成机理;并分别从力学和熵的角度对于提出的机理进行了分析。更多还原

【Abstract】 In recent years, with the development of railway modernization, raising train-running speed and increasing train-hauling load will necessarily increase train vibration force, the vibratory effect of train-running on stability of loess landslides has become a hot issue among Geotechnical engineering insiders. In the thesis, taking the loess landslides and slide-zone soil along the railway as researched subject and combining with geo-technical investigation, laboratory tests, mechanical analysis, theoretical study, numerical calculation, the dynamic characteristics of slide-zone soil and stability of loess landslides under high-speed train vibration load is studied deeply. The main research results of dissertation can be summarized as follows:(1) The cause of formation and characteristics of loess landslides under train vibration load is studied deeply. Through the analysis, train vibration load is thought to be a chief factor which induce the landslides; The characteristics of slide-zone soil is Summed up, and based on the theoretical foundation for laboratory tests of slide-zone soil.(2) By imposing the different cell pressure and dynamic load on slide-zone soil specimens which collected along the typical railway landslides in dynamic tri-axial test, the rules about dynamic strength and dynamic deformation of the slide-zone soil under simulating the train vibration load are studied. The results show that the dynamic strength and cumulate residual strain of the slide-zone soil change with the change of dynamic time and consolidation stress under certain dynamic stress.(3) Based on this test data about slip zone soil dynamic tri-axial test, the BP neural network forecasting model of slip zone soil vibratory subsidence is established, and the results are compared with the multivariate linear regression model. The results show that the assessment of BP neural network forecasting model is more accurate than multivariate linear regression model.(4) The stability of loess landslides under high-speed train vibration load is analyzed by using FLAC. The results indicate that disturbed degree and stability coefficient of the loess landslides change with different train-speed. The results are helpful for the design and strengthening for high-speed railway loess landslides.(5) Through the study about mechanism of loess landslides, the mechanism of loess landslides under minor amplitude and long-term vibration load is proposed. And analysis based on the principle of mechanics and entropy is carried out to prove the proposed mechanisms.更多还原