【作者】 杨庆华；

【导师】 姚令侃；

【作者基本信息】 西南交通大学 ， 道路与铁道工程， 2010， 博士

【摘要】 自组织临界性理论是当代非线性物理学中的前沿理论。是为解释无序的、非线性复杂系统的行为特征提出的新概念。砂堆模型则是研究自组织临界崩滑动力学理论的典型范例,砂堆可以看成一个带有局域相互作用和广延空间自由度的耗散动力系统,在一个微小的扰动作用下将触发连锁反应并导致灾变。因此,本文在“5.12”汶川地震灾区现场调研的基础上,通过砂堆模型离心试验,采用颗粒流方法、三维离散元法数值模拟等技术,在自组织临界性理论概念框架下,对强扰作用下崩塌滑坡动力学特性进行了解释,并围绕强扰作用下崩塌滑坡规模和影响范围等特征开展了一些基础性的研究工作,为铁路、公路边(滑)坡在高烈度地震区的防治工程提供科学依据。主要工作及研究结论如下：(1)对“5.12”汶川地震诱发的次生山地灾害类型、空间分布、影响因素、主要特征等进行了系统的分析论述。其次生山地灾害类型主要有崩塌、碎屑流以及滑坡,还有它们堵江形成的堰塞湖以及引发的泥石流,各灾种之间存在一定的相互转化关系；次生山地灾害主要沿龙门山地震断裂带呈带状分布和沿河流水系成线状分布特点,分布具有明显的上盘效应,发震断裂上盘发育密度明显大于下盘。影响因素除主震诱发因素外,还受到构造断裂带,岩性、地形地貌等其他因素的控制作用。(2)对国道213线都江堰至映秀段以及水磨支线公路边坡崩滑灾害工点开展了详细的调查工作。对公路边(滑)坡的崩滑成灾模式,崩滑作用机理以及崩滑动力学特性进行了分析研究。崩滑成灾模式主要分为岩质边坡崩滑和基覆边坡(基岩与厚覆盖层)崩滑。其中岩质边坡崩滑包括崩滑性滑坡、崩滑、落石3种成灾模式；基覆边坡包括崩坡积体、残坡积体、滑坡堆积体、冲洪积体崩滑4种成灾模式。从崩滑规模和深度出发认为高烈度地震区岩土体崩塌滑坡呈现明显的自组织临界崩滑动力学特性。(3)在课题组前期砂堆实验的基础上,基于拟静力法思想,开展了3种粒径级配的大尺度砂堆模型实验,模拟的实际边(滑)坡高度达到了20.4m,超过了国内外开展的所有砂堆模型实验的尺度标准。实验分别模拟了3种颗粒级配砂堆在3种扰动强度作用下的崩滑现象,扰动强度通过改变不同的底坡倾角来实现,得到了3种不同的崩滑动力学特性：①颗粒均匀的0.5～1.0mm砂堆在变倾角1.5°、3.0°、6.0°时崩滑规模呈现准周期分布；②颗粒均匀的8.0～10.0mm砂堆和非均匀系数φ=3.10的砂堆在变倾角1.5°时崩滑规模服从负幂律分布,呈现自组织临界崩滑动力学特性；③颗粒均匀的8.0～10.0mm砂堆和非均匀系数φ=3.10的砂堆在变倾角3.0°、6.0°时崩滑规模服从正态分布。(4)建立了基于颗粒流理论的PFC2D数值计算模型,对边(滑)坡在不同强扰作用下的崩滑规摸进行了研究。分析了相同尺度的颗粒体系在不同强扰作用下的崩滑规模,以及不同尺度分布颗粒体系在同一强扰作用下的崩滑规模。结果表明：同一尺度分布颗粒体系的崩滑规模随扰动强度增加整体呈现上升趋势,不同尺度分布颗粒体系在同一扰动强度作用下的崩滑规模随粒径范围增大整体呈减小趋势。数值模拟结果与离心模型试验结果具有较好的一致性。(5)运用三维离散元法对重力作用下边(滑)坡的崩滑破坏过程进行了模拟。分析了刚度系数、时间步、阻尼系数、摩擦系数等介质特征参数对崩塌滑坡范围的影响,计算结果表明：摩擦系数是影响边坡崩滑稳定的重要因素,体系破坏后的堆积形态与单元的大小形态关系非常密切,单元越大,体系崩滑破坏后在底部的堆积影响范围越大；相反,单元越小,体系崩滑破坏后在底部的堆积影响范围越小。认为强扰作用下的铁路、公路崩塌滑坡防治工程应按重力作用影响进行考虑,而崩塌落石则需考虑水平地震力的影响。(6)建立了边(滑)坡的崩滑规模灾势评估模型,并根据该模型,完成了川藏公路通麦至105道班沿线各典型边(滑)坡工点在小、中、大震作用下崩塌规模的计算评估。更多还原

【Abstract】 Self-organized criticality theory is in the forefront of the contemporary theory of nonlinear physics, which was put forward is to explain the disorder, the nonlinear behavior of complex systems. Sandpile model is the typical example of studying dynamical theory of self-organized criticality, and it can be seen as an interaction with the local area and wide space extension of the dissipative degrees of freedom dynamic system, a small disturbance will trigger the action of knock-on effect and lead to disaster. Therefore, on the basis of field research of the "5.12" Wenchuan earthquake disaster area, this article through the sand model centrifuge tests, using numerical simulation technology of particle flow method and three-dimensional discrete element method, under the framework of the concept of self-organized criticality theory, explained the landslide dynamiacal charactertics of sand model and slope under strong disturbance, and carried out a number of basic research work focuing on the landslide features such as the scale and scope of slope, for the railway, road slope at high intensity earthquake zone to provide scientific basis for prevention and control engineering. Major work and research findings are as follows:(1) The "5.12" Wenchuan Earthquake-induced secondary mountain hazards types, spatial distribution, influencing factors; the main characteristics were systematically analyzed and discussed. Main types of secondary mountain hazards are avalanches, debris flows and landslides, as well as they dammed lake formed by damming, as well as mudslides triggered by various kinds of disaster exists between the relationship of mutual transformation; secondary disasters, mainly along the Longmen Shan mountain earthquake fault zone and along the river flow was zonal distribution system into a linear distribution of the characteristics, distribution has obvious effects on the plate, the plate developed seismogenic fault density was significantly greater than the footwall. The secondary mountain hazards were controlled by the main factors of earthquake, but also by the tectonic fault, lithology, landforms, and other factors.(2) The article conducted a detailed investigation about landslide hazard of State Highway 213 from Dujiangyan to Yingxiu and Water Mill feeder. The landslide mode, landslide mechanism and landslide dynamiacal charactertics have been analyzed. Landslide disaster mode can be divided into rock slope landslide and bedrock and thick cover layer Landslide, which rock slope landslide include slump of landslides, landslides and falling rock three kinds of disaster mode; bedrock and thick cover layer landslide including the debris deposit, dilapidated and residual soil, accumulation landslide and diluvial deposit four kinds of disaster mode. Departure from the landslide scale and depth of slope, the law of landslide of slope show clear self-organized criticality dynamiacal charactertics.(3) On the basis of prophase sandpile experiment, based on quasi-static force method of thought, carried out three kinds of particle size grading of large-scale sandpile model experiments. According to principle of centrifugal test, the actual slope height reached 20.4m, more than all of the measure of the standard of sandpile model experiments carried ou at home and abroad. Experiments simulated landslide phenomenon of three kinds of particle size distribution sandpile under three kinds of disturbance intensity, disturbances of different intensity were achieved by changing the bottom slope angle, got three different dynamiacal charactertics of landslide:①0.5～1.0mm uniform particle sandpile, landslide scale show a quasi-periodic distribution when the inclination were changed 1.5°,3.0°and 6.0°;②8.0～10.0mm uniform sandpile and non-uniform sandpile ofΦ=3.10, landslide scale subject to a negative power-law distribution, showing self-organized critical landslide dynamiacal charactertics whenis the inclination were changed 1.5°;③8.0-10.0mm uniform sandpile and non-uniform sandpile of = 3.10, landslide scale show a normal distribution, when the inclination were changed 3.0°and 6.0°.(4) PFC2D numerical model was established based on the theory of granular flow and landslide scale of slope were studied under the action of strong disturbance. The numerical model analysised of the landslide scales of the same particle size distribution system under the action of different strong disturbing, and different particle size distribution system under the action of the same strong disturbing. The results showed that:the landslide scale of the same particle size distribution system, increased upward trend with the disturbance intensity to increase, but different particle size distribution system under the action of the same strong disturbing, reduced trend with the size of the particle to increase. Numerical simulation results with centrifuge model test results have good consistency.(5) The landslide failure processes were simulated under gravity by using three-dimensional discrete element method. The stiffness coefficient, time step, damping coefficient, friction coefficient etc. characteristic parameters to impact on landslide scope of slope were analysised. Calculation results show that:the friction coefficient is an important factor to slope stability, the deposit shapes of slope after failure has a very close relationship with cell size, the larger particle unit, the heap greater sphere of influence after failure; On the contrary, the smaller the unit, the heap smaller sphere of influence. At last, under the action of strong disturbance, the railway, road slope landslide prevention engineering should take into account the effects of gravity, while the collapse of falling rock should consider the impact of horizontal seismic force.(6) Finally, this article established a potential disaster assessment model of landslide scale of slope, and according to the model, the author completed the calculation and evaluation of typical landslides of Sichuan-Tibet road from Tongmai to 105 Maintenance under small, medium and large earthquake更多还原