【作者】 孙书伟；

【导师】 朱本珍；

【作者基本信息】 中国铁道科学研究院 ， 岩土工程， 2009， 博士

【摘要】 随着我国基础设施建设步伐的加快,公路、铁路、水电、矿山开采等建设过程中都遇到了大量的边坡问题。在各类边坡问题中,病害边坡的雨季抢险及滑坡变形引起的路基面保通等存在工期紧、施工场地受限等特点,采用传统的治理措施抗滑桩、预应力锚索框架等无法满足快速治理和应急抢险的要求,故往往成为治理工程的难点；尤其是“5.12”汶川大地震后,诸多边坡病害需要进行快速治理,使边坡病害的快速治理问题成为焦点问题,故在优化既有边坡加固技术的基础上研究施工快捷、机械化程度高的边坡加固新技术迫在眉睫。微型桩施工快捷且组合灵活,施工场地小且完全避免了过多的开挖对环境造成的破坏,较适宜于应急抢险工程。自20世纪50年代微型桩技术首次应用以来,尤其是80年代以后,随着钻孔设备的不断改进以及钻孔工艺的提高,微型桩在边坡工程中显示出了较好的应用前景,然而目前关于微型桩加固边坡的受力机制和设计计算理论研究很少且不成熟。基于此,本文在国内外相关研究的基础上,通过现场调查、理论分析、数值模拟、室内试验及现场试验等方法,对微型桩结构加固边坡的受力机制和设计计算理论等进行了系统研究,弥补了国内外相关研究的空白,对滑坡与边坡病害治理技术向轻型化、快速化以及机械化方向的发展起到了推动作用。(1)本文将微型桩按照注浆工艺的不同进行了分类。此外,系统总结了实践中常用的微型桩结构类型,并研究提出了一种以微型桩和预应力锚索为载体的边坡加固新形式—锚管构架。(2)基于弹塑性地基系数法中p-y曲线方法并考虑轴向力的影响,推导了微型桩加固边坡时计算内力和变位的有限差分公式。此外,基于梁柱理论,提出了微型桩截面抗弯承载力的确定方法。(3)通过对微型桩轴向和横向的抗力分析,建立了微型桩结构加固边坡的设计计算新方法。内容主要包括微型桩结构布设位置的选取、设计抗滑力的计算、加固边坡的局部稳定性计算、微型桩的选型、微型桩长的选取、微型桩间距的选取以及顶梁的结构设计方法等。(4)运用FLAC3D及抗剪强度折减技术对微型桩—边坡体系的稳定性进行了耦合分析。同时,采用FLAC3D对6种微型桩结构的抗滑机理和受力机制,以及微型桩结构中各排微型桩受力的不均匀性进行了数值模拟研究。(5)通过室内试验,对微型桩结构与普通抗滑桩的抗滑特性进行了对比分析,系统探讨了二者受力机制的差异性以及采用微型桩结构代替普通抗滑桩的可行性。研究表明,微型桩结构与普通抗滑桩的受力机制具有较大的差异性。此外,试验中微型桩结构的承载力略小于普通抗滑桩,故在一定条件下可以代替普通抗滑桩进行边坡加固。(6)基于青海省省道S101线龙穆尔沟段DH1滑坡治理工程,对框架微型桩结构进行了现场试验研究,并将试验结果与基于p-y分析的理论解进行了对比分析。结果表明,尽管工点滑坡的运动形态较为复杂,但微型桩结构均起到了较好的临时加固作用。实测桩身弯矩与解析解对比分析的结果印证了本文所建立微型桩结构设计计算理论的合理性。(7)进行了工程应用研究,将研究成果应用于扎哈路、燕官路等沿线的的边坡加固工程中,取得了良好的经济效益和社会效益,可供类似工程借鉴、参考。更多还原

【Abstract】 With the development of infrastructure construction, a large number of slope diseases are met in the railway, highway, dam and mine construction. Some slope diseases need to be cured hurry up, just as slope failure induced by rain, the road being cut off by landslide and especially so many slope failures caused by earthquake in Wenchuan on May 12th. These Slope failures are significant hazards to public and private infrastructure, and their maintenance and repair is difficult because the conventional stabilizing methods are too limited to use. Stabilization through the installation of micropiles may solve these problems much easily, which is a relatively new technique for stabilizing slope that has been used successfully in several instances in China and abroad. Micropile technology was evolved continuously since its introduction by Fernando Lizzi in the 1950s. Over the past 20 years, advances in drilling equipment and techniques have extended the applicability of micropiles techniques to slope reinforcement. However, designs for existing applications are immature and have, thus, generally been very conservative out of necessity.Based on case stories, the loaded mechanism of micropile structures and the design method of micropile structures in slope stabilizing are studied in detail by multiple method including site investigation, analytic solution, numerical analysis, modeling test, in-situ experiment and so on.(1) Based on the method of grouting, the micropile classification system is developed. The paper classifies the foundamental types of micropile structure in practice.(2) It presents the method for getting the internal force of single micropile and its bearing capacity.(3) Based on the p-y method, it presents a rational method for the analysis of micropile structure assuming the limit state is failure of the micropile in bending.(4) By numerical analysis, the soil-micropile interaction is silulated based on the explicit-finite-difference code, FLAC3D. The stabilizing mechanism of micropile, the bearing capacity of micropile structure and its effect factors, differential loading among different rows of micropile are analyzed.(5) Based on the model experiments, the bearing capacity and failure model under sliding force between common anti-sliding piles and micropile groups was compared. It was shown that, the micropile group had good anti-sliding ability. Taking 2 mm as the acceptable displacement value of structure in model experiment, the bearing capacity of micropile group was somewhat less than the common anti-sliding pile.(6) Based on the stabilization of DH1 landslide project, in-situ testing study on the mechanical behavior of micropile structure and displacement characteristics of landslide was carried out. The results were compared to a solution for micropile using p-y method. Based on the comprehensive study, it was shown that the stabilizing effect of micropile structure was active and use of analysis method in this paper in design of micropile structure is reasonable.(7) Some micropile structures were adopted in the practice engineering, and the design of the micropile structure was performed using the design approach described in this paper. Several case histories of micropile engineering were presented.更多还原