斜坡力学参数变异性描述及其稳定性预测

发布时间：2018-07-03 07:39

本文选题：斜坡 + 力学参数　；参考：《中国地质大学》2017年博士论文

【摘要】：斜坡变形和稳定性的预测评价是预防灾难性斜坡事件发生的基础性工作。然而实际工作中因斜坡岩土体参数变异性特征使得斜坡稳定性预测评价存在不确定性。岩土体参数变异性主要表现为参数空间分布上的差异性与参数值的不确定性。一方面,岩土体客观存在的非均匀性导致其参数在空间上存在差异性;另一方面,实践中对参数空间分布有限的认识又使得斜坡中岩土体参数具有不确定性。在此状况下所进行的预测实质上是概率化的。基于此,本论文选择研究斜坡岩土体参数的变异性,旨在有效降低斜坡稳定性预测的不确定性并准确评估预测的可靠度。论文以斜坡系统为基础,研究其力学参数(有效杨氏模量E',有效粘聚力c'以及有效内摩擦角φ')变异性及其稳定性预测。首先,在斜坡力学参数与水平位移u_x的时空关联分析基础上,运用逐次线性评估原理建立斜坡力学参数变异性描述方法,并提出勘察资料合理融入初始猜测的方法和以力学参数变异性描述为目的的斜坡水平位移采样策略;随后,在实际复杂工况中探讨非恒定饱和条件下斜坡力学参数变异性对斜坡稳定性的作用机理,描述斜坡力学参数变异性,检验斜坡变形和稳定性的预测效果;接着,通过概率理论建立可行的预测不确定性和可靠度评估方法,量化斜坡变形和稳定性预测中的不确定性和可靠度。最后,提出了斜坡稳定性预测的概率化分析框架。论文主要取得了以下结论与成果:(1)斜坡力学参数与u_x的关联分析:u_x与靠近临空面一侧“x”状共轭斜面的不同单元的E'负相关,与背离临空面一侧“x”状共轭斜面的不同单元的E'正相关;同时,u_x与其水平向临空面一侧单元的E'正相关,与水平向坡内一侧单元的E'负相关。u_x与靠近临空面一侧区域单元上的c'或φ'正相关,与背离临空面一侧区域单元上的C'或φ'负相关。(2)斜坡力学参数变异性描述效果:E'的评估效果好于c'和φ'的评估效果。c'和φ'的评估局限于显著塑性区附近,但评估结果对实际斜坡中软弱区域具有指示识别作用;φ'的评估效果与有效应力大小成正比。通过合理设置监测点的位置、数量以及采样时间,非显著塑性区的c'和φ'以及E'的描述逐渐清晰,相应的不确定性也越来越小。(3)斜坡工程地质勘察资料含有关于斜坡内部物质分布和结构特征的信息。根据数据值和位置的确定情况,通过本文提出的勘察资料融入初始猜测的方法,能够合理地利用这些信息帮助描述斜坡力学参数的变异性。(4)以力学参数变异性描述为目的的斜坡水平位移采样策略:一是监测点的位置决定了反演评估的范围和部位。钻孔或监测点应尽量等间距布置并覆盖斜坡的重点研究区域,防止钻孔或监测点聚集;二是增多监测点数量能够促进参数变异性的描述效果,但过多的监测点效率不高且耗费巨大。实际中应根据项目等级以及项目需求合理设计采样方案。此外,探索多种类型数据融合技术提高斜坡参数变异性描述解析度的十分必要;三是尽可能地选用处于监测过程中不同大小、来自不同方向以及不同机理的外界刺激(如库水变动,降雨等)作用时刻的水平位移监测数据,这样能在固定的采样方案下进一步提高评估效果;四是应根据力学参数空间差异性分布的反演评估结果和预测可靠度分布情况指导进一步调查的重点区域。综合运用参数变异性作用于斜坡稳定性机理判识潜在危险区。这四点为现有的斜坡工程地质勘察提供了新的理论依据。(5)力学参数变异性作用斜坡变形和稳定性的机理:一是通过调控空间不同位置的力学参数大小直接作用于斜坡变形和稳定性;二是通过调整斜坡的应力分布影响到更大区域的稳定性。具体地,E'主要控制的斜坡不同部位的变形,增大了变形的差异性;而c'和φ'控制的是斜坡的不同部位的强度或屈服极限,使得斜坡在任意部位都具有屈服破坏的可能。力学参数和水平位移的时空关联分析结果能够很好地揭示力学参数变异性对斜坡水平位移的作用规律。(6)论文探索性地构建了一种“变异性精细描述——预测”的分析框架。该框架一方面利用掌握的斜坡工程地质勘察基础资料高解析度地描述斜坡的空间差异性分布参数,降低对斜坡变形以及失稳的部位和时间预测的不确定性;另一方面通过定量化地评估预测的不确定性清楚地指示出斜坡不同部位预测的可靠程度,反馈性地指示斜坡参数差异性描述的关键区域;同时结合参数变异性作用斜坡稳定性的机理判识斜坡潜在危险区、把握斜坡稳定性演化趋势,最终实现对斜坡变形和稳定性的可靠预测。结果显示,基于反演评估结果的斜坡水平位移和稳定性预测效果好,能够把握空间变形的差异性和总体趋势。证明了基于参数变异性精细描述的斜坡变形和稳定性预测思路的有效性。
[Abstract]:The prediction and evaluation of slope deformation and stability is the basic work to prevent the occurrence of catastrophic slope events. However, in practical work, the variability of slope rock and soil parameters makes the prediction evaluation of slope stability uncertain. The variability of rock mass parameters is mainly manifested by the difference of parameter space distribution and the inaccuracy of parameter values. On the one hand, on the one hand, the inhomogeneity of rock and soil causes the difference of its parameters in space; on the other hand, in practice, the knowledge of the limited spatial distribution of parameters in practice makes the parameters of rock and soil mass in the slope uncertain. The variability of slope soil parameters is designed to effectively reduce the uncertainty of slope stability prediction and to accurately evaluate the reliability of prediction. Based on the slope system, the paper studies the variability and stability prediction of its mechanical parameters (effective Young modulus E', effective cohesive force C' and effective internal friction angle [Phi]). First, the mechanical parameters of slope On the basis of spatial and temporal correlation analysis of horizontal displacement u_x, the variation description method of slope mechanical parameters is established by using the principle of successive linear evaluation, and the method of rational integration of the investigation data into the initial guess and the sampling strategy of slope horizontal displacement with the purpose of describing the variability of Mechanical parameters is proposed. Then, the non constant in the actual complex conditions is discussed. The mechanism of slope mechanical parameter variability to slope stability, the variability of slope mechanics parameters, and the prediction effect of slope deformation and stability are described. Then, a feasible prediction method of uncertainty and reliability is established by probability theory, and the uncertainty in the prediction of slope deformation and stability is quantified. Finally, a probabilistic analysis framework for slope stability prediction is proposed. The main conclusions and results are as follows: (1) the correlation analysis of the slope mechanics parameters and u_x: u_x and the negative correlation of the different units of the "X" like conjugate slope near the side of the air surface, and the different units of the "X" like conjugate slope on the side of the plane on the side of the plane. The positive correlation of E', and the positive correlation between u_x and its level to the E' on one side of the plane, and the negative correlation between E'and.U_x near the side element of the horizontal slope are positively related to the C' or Phi on the unit near the side of the surface, and negatively correlated with the C'or Phi on the unit on one side of the plane. (2) the evaluation of the variability of the mechanical parameters of the slope: assessment of E' The evaluation effect of C'and phi' is limited to the significant plastic zone, but the evaluation results have an indication recognition effect on the weak areas in the actual slope; the evaluation effect of the evaluation is proportional to the size of the effective stress. By setting the location of the monitoring point, the quantity and sampling time, the C'and phi in the non significant plastic zone by the reasonable setting of the monitoring points. The description of the E'and the corresponding uncertainty are becoming smaller and smaller. (3) the information of the slope engineering geological survey data contains information about the material distribution and structural characteristics of the interior slope. According to the determination of the data and position, the survey data proposed in this paper can be integrated into the initial guessing method, and the information can be used in a reasonable way. The variability of the mechanical parameters of the slope is described. (4) a horizontal displacement sampling strategy aimed at the variation of mechanical parameters: one is that the location of the monitoring points determines the range and location of the inversion evaluation. The drilling or monitoring points should be arranged as far as possible and cover the key areas of the slope to prevent the accumulation of boreholes or monitoring points; and two is the increase. The number of monitoring points can promote the description of parameter variability, but excessive monitoring points are inefficient and costly. In practice, the sampling scheme should be designed reasonably according to the project level and project requirements. In addition, it is necessary to explore various types of data fusion techniques to improve the resolution of the variability of slope parameters; three The horizontal displacement monitoring data of external stimuli (such as reservoir water change, rainfall) in different directions and different mechanisms are selected in the monitoring process, which can further improve the evaluation effect under the fixed sampling scheme; four, the results and pre evaluation results should be based on the spatial difference distribution of mechanical parameters. The distribution of measurement reliability will guide the key areas of further investigation. The four points provide a new theoretical basis for the existing slope engineering geological investigation. (5) the mechanism of the variation and stability of the slope by the variation of mechanical parameters: one is through the control of the empty space. The size of the mechanical parameters between different positions directly affects the deformation and stability of the slope; two is to influence the stability of the larger region by adjusting the stress distribution of the slope. Specifically, the deformation of the different parts of the slope which is mainly controlled by E'increases the difference of the deformation; and C' and [Phi] are controlled by the strength or yield pole of different parts of the slope. The result of the spatial and temporal correlation analysis of mechanical parameters and horizontal displacement can well reveal the action regularity of the variability of mechanical parameters to the horizontal displacement of the slope. (6) the paper explores an analytical framework for the "precise description of variability". On the other hand, the reliability of the prediction of different parts of the slope is clearly indicated by quantitative assessment of the uncertainty of the prediction of the slope deformation and instability. Degree, the key region of the slope parameter differential description is given feedback, and the potential danger zone of slope is judged by the mechanism of slope stability with parameter variability, and the slope stability evolution trend is grasped, and the reliable prediction of slope deformation and stability is finally realized. The result shows that the slope horizontal displacement based on the results of the inversion evaluation results shows that the slope horizontal displacement is based on the results of the inversion evaluation. The effect of the stability prediction is good, and the difference and general trend of space deformation can be grasped. The validity of the prediction method of slope deformation and stability based on the fine description of the parameter variability is proved.
【学位授予单位】：中国地质大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TU433

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