【作者】 罗奇斌；

【导师】 王家鼎；

【作者基本信息】 西北大学 ， 地质工程， 2012， 博士

【摘要】 山西省铁路建设是国家中长期铁路网规划的重要组成部分,区内黄土地层分布十分广泛,且境内铁路沿线地区具有湿陷性的黄土多有分布。潜蚀作为黄土地区一种独特的侵蚀方式,对黄土地区的铁路建设有着非常严重的潜在危害。在具有湿陷性的黄土地区,这种由潜蚀作用所造成的危害更加突出。因此,为确保铁路路线选择的合理性和后期运行的安全性,对湿陷性黄土的潜蚀研究显得尤为必要和紧迫。笔者通过对山西境内新建铁路大同至西安铁路客运专线、山西中南部重载通道、吕梁至临县(孟门)铁路支线三条铁路沿线的环境地质条件及黄土的工程地质条件的详细分析及对黄土潜蚀现象典型区段进行的实地调查,了解掌握了铁路沿线黄土的湿陷性及潜蚀作用的分布特性及规律,掌握了区域内湿陷与潜蚀作用的发育程度及特征。通过笔者独立设计并亲自组织实施的黄土湿陷性大型原位浸水试验对研究区黄土湿陷特征和程度进行了分析与评价。首次将原状黄土浸水试坑与不同厚度灰土改良后黄土试坑进行对比试验,通过对沉降、注水量、土层含水量及土压力变化等的观测与分析,以及对原状黄土及灰土垫层渗透系数的测试,结合对试坑浸水影响范围的分析,评价了灰土垫层的防渗效果及对水分下渗及侧渗的制约作用。鉴于前人所做的现场试坑浸水试验基本上是对试坑内的沉降标进行观测而间接的反应出土层的沉降变形情况,进而确定湿陷深度及湿陷类型。但对浸水过程中不同深度土层的土压力变化情况没有做出相应的测试,对其变化过程及特征了解甚少。笔者首次将土压力数据传感器及水分张力计引入浸水试验,较为精确的记录了试验过程中不同深度土层的土压力的变化特征及土层基质吸力与含水量变化过程,并将此结果与试验沉降观测数据进行了对比分析,了解了其之间的相互关系与变化规律,从而阐明了湿陷性黄土遇水发生湿陷而产生沉降变形的临界条件及时间点。以此为基础,分析了黄土湿陷性对潜蚀发育程度的影响及控制性作用。结合前人研究成果,进行了黄土原位崩解性试验,对黄土的平均崩解速率、瞬时崩解速率、崩解量及其影响因素等进行了分析研究；通过独立设计并亲自组织实施的以人工降雨模拟为依托的黄土抗冲刷性试验,笔者首次对不同降雨强度(冲刷强度)及不同崩解速率下的黄土冲刷性进行了试验对比,分析研究了黄土抗冲刷性与崩解性及冲刷强度之间的相互联系,以及其与黄土潜蚀作用的关系；阐明了崩解为潜蚀提供了物质条件,冲刷作用对崩解所产生的物质进行搬运,使潜蚀作用得以持续进行的侵蚀过程。分析了黄土崩解性及抗冲刷性对潜蚀发展速率及发育规模的控制性作用。通过上述野外原位试验及室内的研究结果,结合对研究区黄土湿陷与潜蚀各种影响因素的分析,鉴于湿陷性对黄土潜蚀的控制性作用,首次提出以湿陷系数为指示指标,对铁路沿线的潜蚀分布程度进行模型预测。在室内试验的基础上,通过分析影响湿陷性的因素,确定了与湿陷系数有关的物理指标,利用MATLAB模糊神经网络工具箱,采用自适应模糊神经网络(ANFIS)方法,建立了湿陷系数与选取的主要影响因素之间的模糊关系,同时建立多元回归模型,并比较了这两个模型的预测精度。通过对湿陷程度的预测间接的实现了对潜蚀分布程度预测。进而提供了一种良好的湿陷性黄土区潜蚀预测方法,为铁路建设提供了防灾依据。最后,论文总结了铁路沿线黄土湿陷与潜蚀的工程危害类别及特点并提出了相应的防治措施。更多还原

【Abstract】 Railway construction in Shanxi Province is an important part of the national medium-and long-term railway network plan, and Shanxi provinces as an important component of China’s Loess Plateau, the loess stratigraphic distribution in the region is very broad, and the territory of the areas along more than a distribution of collapsible loess.Potential erosion as a unique way of erosion in the loess region, the loess areas of railway construction with a very serious potential harm. Collapsible loess areas, the harm caused by this potential erosion is more prominent. Therefore, in order to ensure that the railway route choice rationality and post-operation safety, the potential erosion of collapsible loess research is particularly necessary and urgent.In this thesis, Shanxi Province, the new railway from Datong to Xi’an Railway Passenger, environmental and geological conditions of Shanxi in central and southern overloaded channel. Luliang to Linxian County (Meng Gate) railway extension23along the railway line and the loess of engineering geological conditions of a detailed analysis and A field survey of typical sections of the loess potential erosion phenomenon to understand the distribution characteristics and laws of the railway collapsibility and potential erosion, to grasp the degree of development and characteristics of the potential erosion in the region.Collapsible loess and loess dust improved the field of independent design and personally organized and implemented large-scale test pit flooding contrast test, and the first earth pressure sensor and the moisture tension meter the introduction of the test, in collapsible loess along the railway line carried out a detailed analysis of study to clarify the District loess collapsible and collapsible distribution of submarine erosion control; of independent design and personally organized the implementation of the loess in situ disintegration test and to artificial rainfall simulation relying on loess erosion resistance test, for the loess disintegration of the potential erosion process, the linkages between the erosion resistance as well as controlling both the degree of development and developmental scale of the potential erosion.Through the field in situ testing and indoor findings, combined with the analysis of the study area are loess subsidence and the potential erosion of various factors, view of the collapsible loess potential erosion controlling the coefficient of collapsibility for instructions indicators, a model to predict the distribution of the degree of potential erosion of the railway, on the basis of the laboratory experiment, by analyzing the impact collapsible factors to determine the physical indicators related to the coefficient of collapsibility, the use of the MATLAB Fuzzy Neural Network Toolbox, using self-to adapt the fuzzy neural network (ANFIS) to establish the fuzzy relationship between the coefficient of collapsibility and select the main factors, a multiple regression model, and compare the prediction accuracy of these two models.Predict the Extent of the collapsible indirect distribution of the degree of prediction of the potential erosion. Thus provides a good collapsible loess potential erosion prediction methods for railway construction disaster prevention. Finally, the paper summarizes of loess collapsibility of railway engineering and the potential erosion hazard categories and characteristics and corresponding measures.更多还原