【作者】 周斌；

【导师】 张可能；

【作者基本信息】 中南大学 ， 地质工程， 2010， 博士

【摘要】 边坡是公路建设中最普遍也是极为重要的地质环境,从理论到工程实践,前人已经进行了很多研究,但在实际中仍存在诸如不确定性等难以解决的问题。常吉高速公路沿线分布的大量的红砂岩,易风化崩解、长期强度低,且岩层产状多为单斜缓倾构造,易变形,稳定性很差,极容易出现顺层滑坡等工程问题。在分析传统的以安全系数作为边坡稳定性评价尺度的方法的基础上,同时考虑岩土参数的不确定性,建立具有湘西地域特点的可靠度分析模型和风险评估体系,使工程师根据所选择的风险评估结果进行边坡工程设计,能更有效地协调工程的近期投资和长远效益之间的矛盾。(1)通过试验分析研究了湘西红砂岩的矿物成分、化学成分、基本物理性质、水理性质和力学性质,并分析了其膨胀机理。(2)采取三种方案对湘西红砂岩的浸水崩解特性进行了专门研究,指出了红砂岩的崩解稳定是相对的,提出了红砂岩耐崩解性的定量评价方法。(3)通过三轴压缩数值试验,分析了三轴应力状态和结构面倾角对层状岩体变形破坏的影响。试验结果表明,随着结构面倾角的增大,层状岩体三轴抗压强度呈现先减小后增大的趋势,岩体的强度异性程度与围压有关,软硬夹层岩样之间存在交互作用。(4)通过直剪试验详细分析了含水率对泥化夹层抗剪强度参数的影响,指出了水岩相互作用是导致泥化夹层强度降低、顺层边坡失稳的主要影响因素之一。(5)研究了边坡岩体在自重应力场和构造应力场作用下,地应力的修正计算方法,从岩体损伤的角度,揭示了地应力对红砂岩顺层边坡稳定性的影响。根据Mohr-Coulomb准则,引入破坏接近度的概念,提出了修正地应力造成的岩体损伤评价方法,并与岩体损伤破坏评价五个等级对应起来,建立起Q值与岩体损伤等级的对应关系。(6)对湘西红砂岩顺层边坡的可靠度分析基本原理、分析方法和岩士参数的统计处理进行了研究。(7)湘西红砂岩顺层滑坡往往是沿泥化夹层层面发生的,针对这一特点,建立了相应的地质模型、力学模型和可靠度分析模型。(8)从风险识别、风险分析、风险评价和风险管理四个方面初步建立了湘西红砂岩顺层边坡的风险评估体系。(9)在边坡失稳概率的选择上,提出了应在基于历史滑坡频率的概率和基于边坡失稳的潜在性概率中选择最大失稳概率来作为边坡设计失稳概率的观点。更多还原

【Abstract】 Slope is the most common and extremely important geological environment in highway construction. The previous have studied a lot from theory to engineering practice, but some problems such as uncertainty are still hard to solve in practice. Lots of red sandstone with characteristic of easy weathering, easy disintegration, low long-term strength, slow tilt single interbeds, poor deformation and stability distribution along with Chang-Ji highway. It is easy to occur bedding slope. Based on the traditional safety factor, consider of the uncertainty of geotechnical parameter, a reliability analysis and risk evaluation system with the region characteristic of western Hunan is built to make the engineer design according to the results of risk assessment.The conflict between recently investment and long term benefits of the project can be more effectively coordinated.(1) The mineral composition, chemical composition, physical properties, water-physical properties, mechanical properties and expansion mechanism of the red sandstone are studied by experiments.(2) The crumbling property in soaking of the red sandstone is studied by three schemes. It points out that the crumbling stability of red sandstone is relative. A quantitative evaluation method of red sandstone crumbling is put forwarded.(3)The influence of triaxial stress state and tilt single of the structure plane in deformation and failure of layered rock mass is analysed by numerical simulation. Experimental results show that, with the increase of tilt single of the structure plane, the triaxial compression strength of layered rock-mass first decreases and then increases.The anisotropic strength of the rock is related to confining pressure. Interaction exists between soft interlayer and hard interlayer.(4)Through direct shear tests, the influence of moisture content on shear strength parameters of muddy intercalation was studied in detail. The influence of water-rock interaction is considered as one of the main influencing factors causing bedding slide.(5) The correction calculation method of ground stress in slope rock mass under the gravity stress and tectonic stress field was studied. The influence of ground stress to red sandstone bedding slope stability is revealed from the rock damage. According to the Mohr-Coulomb criterion, the concept of destruction approaching degree is introduced to promote the evaluation analysis for the rock mass damage based on the revised ground stress, and the proposed evaluation method is in accordance to the 5 levels of rock mass damage class, which in turn build the corresponding relationship of Q value with the rock mass damage.(6) The basic principles and analysis methods of reliability,as well as the statistics processing of geotechnical parameters of red sandstone bedding slope in western Hunan is studied.(7)The red sandstone bedding slide in werstern Hunan often occurs along the muddy intercalation. According to this characteristic, the corresponding geological model, mechanical model and reliability analysis model are established(8)The risk assessment system of red sandstone bedding slope in werstern Hunan is established from the four aspects:risk identification, risk analysis, risk evaluation and risk management.(9) In slope instability probability, one is based on the frequency of historical slide, the other is based on potential slide. we should select the maximum instability as slope design instability.更多还原