山区机场高填方地基变形和稳定性分析

发布时间：2018-06-01 12:43

本文选题：高填方 + 地基变形　；参考：《兰州理工大学》2017年博士论文

【摘要】：在“18亿亩耕地”不能触碰的红线下,山区城镇化和“一带一路”战略实施所需要的建设用地大多通过削山填沟造地解决;然而部分填方工程的最大填方高度及“三面两体两水”问题不断刷新,由此引发了一系列新的岩土工程问题,其中最突出的核心难题就是高填方地基变形计算和高填方边坡稳定性分析。基于此,依托陇南成州民用机场高填方工程,以非饱和土力学为基础,采用多种研究方法和高新先进技术,深入探索了山区高填方地基处理,全面揭示了混合料填筑土体的变形、强度及持水特性,系统分析了高填方施工过程和工后变形时空变化规律,重点解决了高填方地基变形计算和稳定性评价等问题。研究成果不仅可以用于相关规范标准制定、为类似高填方工程提供科学依据,而且具有重要的理论价值和显著的社会经济效益。论文完成的主要工作、创新点及获得结论如下:(1)基于试验段进行的填料配比试验、原地基处理试验、填筑体压实试验、挖填交界处理等系列试验,发现高填方原地基中的粉质粘土层是地基中相对软弱层,对高填方地基沉降与差异沉降及地基稳定性控制起着决定性作用;给出了不同厚度软基强夯处理工艺参数和填筑体压实、挖填交界面处理及质量控制建议;建立了强夯有效加固范围和加固影响范围计算方法;提出了填筑体压实施工过程监控系统,可为高填方地基大面积动态信息化设计和施工提供科学依据;(2)对土石混合料填筑体及挖填交界处土体进行现场原位剪切试验,发现泥岩与土体接触带或缝隙是薄弱区域,最先可能演化为凹凸状剪切面;挖填交界处的边坡比大面积填筑体边坡更容易发生剪切破坏,施工过程中应加强处理。通过室内直接剪切试验、高压压缩试验,给出了大面积填方施工填料控制建议,建立了一种考虑填方土体初始状态的抗剪强度算法和沉降变形算法。通过系列三轴试验,深入揭示了原地基土体和混合料填筑体的强度、变形与持水特性,为本构模型修正和数值模拟计算奠定了理论基础;(3)伴随施工过程,首次在试验段设计并安装了山区高填方无线远程综合监测系统,揭示了加载期和工后一定时间内原地基土体和填筑体的沉降、变形、孔隙水压力及土压力等时空演化规律,取得了一系列新的认识。同时,在全场区典型部位进行常规工后变形监测,基于现场监测给出了高填方工后沉降和差异沉降控制建议,通过现场实测数据对工后沉降进行预测分析,为合理确定机场道面开始施工时间及评价道面使用年限内的工后沉降提供科学依据;(4)在室内外试验完成的基础上,建立了基于分层总和法计算高填方地基竖向沉降和侧向变形的理论表达式,解决了高填方地基变形计算问题;采用MATLAB软件编写了山区高填方地基变形计算程序,经对比证明算法正确合理。采用有限元软件模拟分析发现,在施工期应严格控制填方地基的沉降与差异沉降;工后第一年沉降约占工后沉降的60%,工后第二年沉降量约占工后沉降的30%,工后3~5年沉降量约占工后沉降的10%,工后沉降总体不超过20cm;工后第一年不应进行道面施工,条件允许时应放置1~2个雨季;(5)对高填方边坡滑移变形过程进行监测和反演分析发现,山区高填方边坡变形以沉降为主、兼有明显水平侧向位移,属于典型的人工加载的“后推式”滑移类型;提出了山区高填方边坡不同变形阶段的时空演化特征与变形速率预警判据。结合修正的Duncan-Chang模型参数和非饱和土破坏时的强度准则,建立了变模量双强度折减法,初步探讨了其用于高填方边坡稳定性评价的新思路。率先提出采用柔性结构加固刚性失稳挡墙的新型支挡结构,并推导建立了其动静力稳定性计算方法。
[Abstract]:In the "1 billion 800 million acres of arable land cannot touch the red line, the construction of mountain towns and" The Belt and Road "strategic implementation of the necessary land mostly through the mountain cut fill gap creates to solve problems; however, the maximum height of the embankment fill part of engineering and the" three two two "water constantly refresh, which triggered a series of new geotechnical problems, The most outstanding core problem is the high fill foundation deformation calculation and the high fill slope stability analysis. Based on this, relying on the Longnan Cheng Zhou civil airport high fill project, based on the unsaturated soil mechanics, using various research methods and advanced advanced technology, the high fill foundation treatment in the mountain area is deeply explored, and the mixture is fully revealed. The deformation, strength and water holding characteristics of the soil are filled. The construction process of high fill and the time and space change law of post work deformation are systematically analyzed. The problems of calculation and stability evaluation of high fill foundation are solved. The research results can not only be used in the formulation of relevant standard standards, but also provide scientific basis for similar high fill engineering, and it has heavy weight. The main work, innovation and conclusions are as follows: (1) a series of tests of filler ratio based on the test section, ground base treatment test, compaction test, dug and fill boundary treatment and so on, found that the silty clay layer in the high fill foundation is relatively soft in the foundation. The weak layer plays a decisive role in the settlement of the high fill foundation, the differential settlement and the stability control of the foundation, and gives the suggestions on the processing parameters of the soft foundation and the compaction of the fill, the treatment of the interfacing and the quality control, and the calculation method of the effective consolidation range and the influence range of the consolidation, and the implementation of the filling body pressure is put forward. The working process monitoring system can provide scientific basis for large area dynamic information design and construction of high fill foundation. (2) in situ shear test of soil and rock fill material and excavation at the junction of soil and fill, found that the contact zone or gap between clay and soil is weak area, and first may evolve into concave convex shear surface; The slope is more prone to shear failure than the large area fill slope, and the treatment should be strengthened during the construction process. Through the indoor direct shear test and high pressure compression test, the suggestion of filling control for large area fill construction is given. A kind of anti shear strength algorithm and settlement deformation algorithm, which considers the initial state of fill soil, is set up. A series of three axes are adopted. The strength, deformation and water holding characteristics of the original soil and mixture fill are revealed in depth. (3) with the construction process, the high fill wireless remote monitoring system is designed and installed in the test section for the first time, which reveals the loading period and a certain time after the work. A series of new understanding of the settlement, deformation, pore water pressure and earth pressure of the soil and filling body of the original foundation has been obtained. At the same time, the deformation monitoring of the typical parts of the whole field is carried out after the conventional post work deformation. Based on the field monitoring, the suggestions for the control of the post settlement and differential settlement of the high fill are given. The settlement is predicted and analyzed to provide a scientific basis for the reasonable determination of the construction time of the airport pavement and the evaluation of post construction settlement within the service life of the road. (4) on the basis of the completion of the indoor and outdoor tests, a theoretical expression of the vertical settlement and lateral deformation of the high fill foundation based on the stratified summation method is established to solve the change of the high fill foundation. MATLAB software is used to compile the calculation program for the deformation of high fill foundation in mountain area, and it is proved that the algorithm is correct and reasonable. By the finite element software simulation analysis, it is found that the settlement and differential settlement of the fill foundation should be strictly controlled during the construction period, and the settlement of the first year after work is about 60% of the post work settlement, and the settlement amount is about second years after the work. After 30% of the post work settlement, the settlement of 3~5 years after work accounts for about 10% of the post work settlement, and the post construction settlement is not more than 20cm. The first year of work should not be carried out in the road surface construction, and the 1~2 rainy season should be placed when conditions permit. (5) the monitoring and inversion analysis of the sliding deformation process of the high fill slope found that the deformation of the high fill slope in the mountain area is mainly settlement, and there is also obvious settlement. The horizontal lateral displacement is a typical "backstepping type" type of artificial loading. The temporal and spatial evolution characteristics of the high fill slope in the mountain area and the early warning criterion for the deformation rate are put forward. The variable modulus double strength reduction method is established by combining the modified Duncan-Chang model parameters and the strength criterion of the unsaturated soil failure. A new way of evaluating the stability of high fill slope is discussed, and a new retaining structure is put forward to reinforce the rigid instable retaining wall with flexible structure, and its dynamic and static stability calculation method is derived.
【学位授予单位】：兰州理工大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：V351.1

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