【作者】 姜屏；

【导师】 程永春；

【作者基本信息】 吉林大学 ， 道路与铁道工程， 2012， 博士

【摘要】 在国民经济基础设施建设中，如高速公路建设、隧道和地铁施工、基坑开挖等，形成了各种各样的土质边坡。土质边坡尤其是季节冰冻区土质边坡，在降雨和冻融循环作用下，由于边坡土体的抗剪强度受到损伤而导致滑坡。滑坡灾害的产生是一个逐渐发展的过程，如果能通过监测手段及时掌握土质边坡变形和稳定性的变化规律，是有时间对土质边坡进行加固处理和及时提出预警措施，这样就能有效地防止滑坡的发生和降低滑坡带来的危害。边坡安全监测主要是通过一定的监测手段获得边坡的位移值、应力应变和地下水位等参数，通过设定警戒值的方式来对边坡的安全状态进行分析。当监测值小于警戒值时，认为边坡处于安全状态；当监测值超过警戒值时，则认为边坡处于危险状态。这种通过设定警戒值的方式来判断边坡的稳定程度具有很大的经验性，往往由于警戒值设定的不合理，使得对边坡稳定性出现错误的判断。随着边坡稳定性分析方法的发展，目前经常使用的稳定性分析方法包括极限平衡法和强度折减法等。这些计算方法能够准确地计算出边坡的稳定安全系数。但是，边坡土体力学参数的获取，是目前进行边坡稳定性分析的难点所在。毫无疑问，实验室测试和现场试验是解决这一问题的有效方法，但是这两种方法各有其局限性。由于用于室内试验的土样往往都是扰动土，与原状土的力学性质具有很大的区别，并且现场采取的土样具有较大的随意性，代表性差。这就使得通过室内试验获得的土的力学参数与实际的土的力学参数具有较大的偏差；而局部的有限的原位测试获得的少数几个测试结果，并不能代表整个边坡的土体的力学性能，并且原位测试的费用往往是相当昂贵的，因此原位测试技术也不能有效的获得边坡土体的力学参数。因此，要直接通过测试技术获得边坡土体的力学参数而进行边坡稳定性分析，存在很大的困难。参数反演方法能够根据边坡安全监测结果得到边坡土体的力学参数，进而对边坡的稳定性进行分析。因此，参数反演方法能够有效地将边坡安全监测和稳定分析结合起来，克服了岩土工程中边坡监测和稳定性分析独立发展的缺陷。随着监测技术的发展，边坡位移的实时远程监测已经成为可能，能够实时的掌握边坡变形状态。通过位移参数反演计算能够得到边坡土体力学参数，从而能够计算边坡的稳定性。因此，对边坡位移监测、参数反演算法和边坡稳定性的研究具有重大的理论与现实意义。为了建立起季节冰冻区边坡变形和稳定性之间的关系，通过边坡位移监测实现对边坡稳定性的分析，本文结合国家高新技术研究发展项目（863项目）“季节冰冻区大范围道路灾害参数监测与辨识预警系统研究”（2009AA11Z104）开展了以下几方面工作：1、介绍了边坡表面和深部位移监测的主要方法及基本原理，并对各监测方法的适用条件和优缺点进行了总结。对课题组研制的边坡位移远程监测系统进行了介绍，此系统成功应用于长春西客站深基坑的位移监测，取得了良好的效果。2、根据极限平衡法和强度折减法，得出了边坡的几何因素（边坡高度，边坡角度和坡面形态）和边坡土体的抗剪强度参数（粘聚力和内摩擦角）是边坡稳定性的主要影响因素。针对数值算例，采用有限差分强度折减法计算了各影响因素取不同值时的边坡稳定安全系数，并且介绍了采用强度折减法计算边坡安全系数时，边坡滑动面位置的确定方法。最后采用单因素敏感性分析法，计算了各影响因素对安全系数的敏感性因子。3、考虑影响土质边坡稳定性的主要外界环境因素为降雨和冻融循环。介绍了土体抗剪强度的基本理论及影响因素，对长春西客站深基坑不同深度的四种土样进行室内试验。研究不同含水量和冻融循环次数对边坡土体抗剪强度参数（粘聚力和内摩擦角）的影响规律，为分析外界环境因素对长春西客站深基坑稳定性影响提供依据。4、基于强度折减法的基本概念，根据土体的Mohr-Coulomb本构关系，将强度折减系数代入本构矩阵，采用有限元方法计算边坡位移。得出了边坡处于不同稳定状态时的位移值。由于边坡位移是最容易精确获取的参数，采用神经网络算法拟合强度折减系数与边坡位移之间的函数关系。通过实测边坡位移值就能得到边坡稳定性的折减程度，从而得到边坡的稳定程度，并通过一数值算例对此计算过程进行了说明。5、为了根据边坡位移获得土体力学参数的变化规律，本文采用遗传神经网络对边坡土体的力学参数进行反演计算。采用遗传算法对神经网络的初始权重和偏置值进行优化，得到最优的神经网络拓扑结构。采用此神经网络建立起边坡位移和土体力学参数之间的关系，并通过一数值算例具体介绍了遗传算法优化神经网络拓扑结构的过程，以及Mohr-Coulomb模型参数反演的计算方法。6、本文采用有限元方法计算了在外荷载作用下长春西客站深基坑支护结构的变形，并得到了冠梁的作用荷载和内力分布。在外荷载增大，冠梁达到极限承载力时，提出采用碳纤维对冠梁进行加固，并采用ANSYS软件模拟计算了碳纤维加固冠梁的承载力和变形特征。7、本文对长春西客站深基坑的安全监测方法和监测结果进行了介绍，同时将本文提出的方法运用于基坑土坡的稳定性评价，根据实测位移数据即能实时掌握边坡的稳定状态，从而保障了基坑施工的安全性，为基坑安全监测与稳定性分析提供了实践参考。更多还原

【Abstract】 In the construction of national economy infrastructure, just like highway, tunnel andsubway construction and excavation, etc, a variety of soil slopes were formed. Soil slopeespecially in seasonal frozen area, the role of rain and freeze-thaw cycles leads to shear strengthof soil damage and slide. If we can master the characteristic of slope deformation and stabilitythrough monitoring, the landslide can be prevented effectively by taking correspondingmeasures and landslide disaster lowered by early warning.Due to the generation of landslide disaster is a gradual process of development, if we canmaster the change rule of soil slope deformation and stability in time, there is enough time toreinforce soil slope or provide early warning measures, it can prevent occurrence of landslideand reduce the landslide hazards effectively.At present, safety monitoring of the slope contains monitoring of slope displacement,stress-strain and underground water level and other parameters, and analysis slope safety stateby setting the alarm value approach. If the monitoring value is less than the warning value, theslope is in a safe state. If the monitoring value exceeds the warning value, the slope is in adangerous state. It has great experience to set a threshold value to judge the slope stability state,usually making error judgment of slope stability due to alert value setting unreasonable.And for the analysis of slope stability, along with the development of slope stabilityanalysis method, current regular use of stability analysis method such as the slice method andstrength reduction method, can accurately calculate the slope stability safety factor. However,the acquisition of slope soil mechanic parameters is the current difficulties in slope stabilityanalysis. Because of the soil is not uniform, and the internal distribution is discrete andasymmetry. The soil mechanical parameters for calculation are generally obtained by laboratorysoil test, and the soil samples are coming from the field. The soil samples for laboratory test areoften disturbed, and the soil properties are quite different. If using in situ testing for soil slopemechanical parameters, the test results can not represent the entire slope soil mechanicalproperties due to in situ test, obtaining only a few points of soil sample test results, and the insitu test cost is often quite expensive. Due to the difficulty of obtaining the mechanicsparameters of soil slope, there are difficulties in slope stability calculating, so that we usuallycannot analysis slope stability in real-time. Parameter inversion method can obtain slope soil mechanical parameters according to theslope safety monitoring results, and analysis the slope stability. So, this method can combineslope safety monitoring and stability analysis effectively, which has overcome detects of slopemonitoring and stability independent development in the geotechnical engineering. Along withthe development of monitoring techniques, slope safety real time remote monitoring hasbecome possible, which can obtain slope deformation state in real-time. Slope soil mechanicalparameters can be obtained by parameter inversion calculation, which can be used to calculatethe slope stability. Therefore, the research of slope displacement monitoring, parameterinversion algorithm and slope stability analysis has great theoretical and practical significance.In this paper, combined with national high technology research and development plan (863project) named ‘Research of large range road disaster parameter monitoring and identificationand early warning system in seasonal frozen region’, several aspects of research work havebeen carried out as follows:1. The main method and basic principle of slope surface and deep displacement monitoringwas introduced, the suitable conditions, advantages and disadvantages of these monitoringmethods are summarized. The slope displacement remote monitoring system developed by thestudying team was introduced, this system was successfully applied in Changchun west railwaystation deep foundation pit displacement monitoring, and achieved good results, which canprovide reference for slope displacement monitoring.2. According to the calculation method of slope stability, limit equilibrium method andstrength reduction method, the effect of slope geometry factors (slope height, slope angle andslope morphology) and slope soil shear strength parameters (cohesion and friction angle) onslope stability have studied. The sensitivity of the influencing factors on the slope stabilitysafety factor has calculated through a numerical example. The method for determining theposition of slope sliding surface has adopted strength reduction method.3. Due to changes in the external environment such as rainfall and the effect of freeze-thawon soil slope effect, this paper argues that affects the stability of soil slope is affected mainly bychanging the soil shear strength parameters (cohesion and friction angle) value. The effect ofdifferent water content and freeze-thaw cycles on the slope soil shear strength parameters(cohesion and friction angle) has studied by laboratory test.4. Because we can not establish the relationship between the deformation and the stabilityof slope, according to the basic concept of strength reduction method, the function relationshipbetween slope displacement and strength reduction coefficient is obtained, combined with the finite element method to get the function relationship between slope displacement and strengthreduction coefficient. In order to get the safety coefficient of slope stability by monitoring, theneural network algorithm is used to simulate the function relationship between strengthreduction coefficient and slope displacement, through measuring the slope displacement valuescan get the reduction of slope stability, and also obtain the slope stability state.5. In order to better grasp the slope stability, this paper adopts the displacement parameterinversion method to calculate mechanic parameters of soil slope by intelligent inversion. Thegenetic algorithm has been used to optimize the initial weights and bias values of neuralnetwork, thus the optimal topology structure of neural network is established, which can satisfythe precision requirement of inversion calculation.6. In order to guarantee the safety foundation pit support structure, the finite elementmethod was used to calculate the deformation of supporting structure under loads, and the loadand internal force distribution of the top beam was obtained. When external loads reach thevalue, top beam reaches the ultimate bearing capacity. The CFRP is used to reinforce the topbeam. And ANSYS was used to calculate the bearing capacity and deformation characteristic oftop beam reinforced by CFRP.7. The safety monitoring method and the monitoring results of Changchun west railwaystation deep foundation pit have been introduced, and the method proposed in this paper areused to evaluate the stability of foundation pit, so that slop stability state can be obtainedaccording to the measured displacement data. So, the safety of foundation pit construction hasprotected, and can provide practical reference for foundation pit safety monitoring.更多还原