【作者】 孙乾锋；

【导师】 邓荣贵；

【作者基本信息】 西南交通大学 ， 岩土工程， 2008， 硕士

【摘要】 在交通运输、矿山开采、水利和国防等建设工程中,存在着大量的高边坡。确保这些高边坡在施工和运营过程中的稳定,对于保证整个建设工程的顺利开展和应用具有非常重要的意义。本文以四川犍为县人民医院门诊大楼后边坡为研究对象,运用工程地质、岩体力学、数值模拟等理论和方法,研究了边坡的变形破坏机理及其稳定性,提出了确保边坡长期稳定的支护方案。取得了以下几个方面的研究成果:1、利用工程地质力学分析原理,对该边坡的变形破坏机理及破坏模式进行了分析研究,结果表明,缓倾角泥化夹层、下部相对软弱的粉砂质泥岩浅部的风化及软化变形、与边坡走向近乎平行和垂直的两组陡倾节理面是导致边坡破坏的主要原因。随着边坡的开挖,中上部巨厚层状砂岩层中陡倾节理面由于应力释放和回弹变形而被拉开,下部软弱基座浅部发生差异变形,当雨水渗入张开节理面,孔隙水压力有所增加而泥化夹层的力学性质进一步恶化,最终边坡发生以座落为主的滑动破坏。2、利用极限平衡法中的不平衡推力法和Spencer法,对该边坡的稳定性进行了分析评价,认为该边坡在不利的自然营力作用下很难保持自身稳定;为了了解不平衡推力法理论假设的可靠性,分析了条块间作用力倾角与稳定系数的关系,结果表明条块间作用力倾角对该边坡的稳定系数影响很大;考虑到不平衡推力法在国内应用广泛的实际情况,利用切角法对其进行了改进处理,切角处理后的不平衡推力法计算结果与Spencer法计算结果基本一致,该结果客观反映了边坡的稳定状态。3、在认识了边坡变形破坏机理和稳定状态的基础上,对该边坡提出了综合治理方案,即系统的排水措施和预应力锚索框架梁支挡措施,结合前人研究成果对预应力锚索框架梁进行了优化设计,结合该实际工程的研究对现有的设计理论作了的一定的改进。4、利用FLAC^3D软件对边坡的变形破坏机理进行了数值模拟,验证了工程地质力学分析结论的可靠性;结合强度折减法理论和数值分析方法计算出边坡的稳定系数,与极限平衡法的分析结果接近;为了评价边坡治理方案的合理性,通过FLAC^3D中的结构单元模块分析了边坡加固前后的应力和位移等的变化,进一步验证了预应力锚索框架梁治理措施的显著效果。更多还原

【Abstract】 There are many high slopes in some projects such as communication engineering, mining engineering, hydraulic engineering and national defence construction etc. In order to keep these projects well developing and operating, it is important to make these high slopes stability during the time of construction and operation. In this paper, the high slope is taken as an example, which is behind the outpatient building of Qianwei people hospital in Sichuan province. According to the theory and methods which are from Engineering Geology, Rock Mass Mechanics, and Numerical Simulation etc., the author analyses the deformation damage mechanism and stability of the slope, and provides some optimizing support-scheme to make the slope long-time stability. The acquired results are as follows:1、On the basis of the mechanics analysis principle of Engineering Geology, the author analyses the deformation damage mechanism and establishes the model of destruction of the slope. The results show that the leading cause of deformation and destruction lies on a low dip angle siltized intercalation, the shallow weathering and deformation of soft silty sandy mudstone, and two sets of high dip angle joint planes that are nearly parallel and perpendicular to slope strike. Firstly, two sets of high dip angle joint planes among derrick thick sandstone are opened and the differentia deformations occur in soft underlying stratum because of stress-release and rebound deformation, while the slope is dug. Then, pore water pressure on joint planes is augmented and the mechanics characteristic of siltized intercalation is further weakened, while rainwater seeps in the opening joint planes. Finally, the slope mainly slips downward in above disadvantage circumstance.2、According to imbalance thrust force method （ITFM） and Spencer method, which are from limited equilibrium method, the author analyses the stability of the slope and evaluates its stabily state. It is indicated that the slope is hardly to maintain its stability in the bad circumstance. In order to discuss the reliability of theoretical hypothesis which is deduced by ITFM, the relationship between the dip angle of inter-slice force and stability factor is fully analyzed. The results show that the dip angle of inter-slice force has a great influence on stability factor. ITFM has been widely used in the field of slope stability analysis, so the author adopts QieJiao method （the unfit node is continuously divided） to improve ITFM. The error between QieJiao method and Spencer method is ignored during calculating stability factor of the slope.3、Based on the deformation damage mechanism and stabily state of the slope, a reasonable support-scheme including the systemic draining and the prestressed cable frame beam is put forward. According to the previous research fruits and the practical project, the author brings up optimizing design for the prestressed cable frame beam and improves on some optimizing methods.4、Through comparing the results obtained by Fast Lagrangian Analysis of Continua in Three-dimension (FLAC^3D) with the mechanics analysis of Engineering Geology, it is indicated that the latter is almost accordant to the former. In light of numerical simulation method based on strength reduction theory, the author works out stability factor that is almost equal to the results by limited equilibrium method. In order to evaluate the support-scheme of the slope, the author analyses the difference of stress and displacement in two state （reinforce and non-reinforce） by the structural elements model of FLAC^3D. The results show that the prestressed cable frame beam is an effective support-scheme.更多还原