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基于GIS的巴东新县城滑坡灾害风险系统 总被引：3，自引：0，他引：3
本文提出了基于GIS的滑坡灾害风险预测系统流程。并将滑坡灾害风险评价模型与GIS技术先进的图形处理和空间分析功能相结合,建立了巴东县新县城区滑坡灾害风险预测系统。系统由信息管理子系统、危险性预测子系统、易损性预测子系统、风险预测子系统四大子系统构成。系统在对相关信息进行采集、存贮、检索和管理的基础上,结合物元模型、BP模型等专业预测模型,实现了滑坡灾害危险性、易损性评价,最终取得了滑坡灾害风险分布图,为三峡库区内各县的滑坡灾害信息管理和风险预测提供了新途径。预测成果可为研究区的国土规划和移民工程的顺利实施提供依据和保障。 相似文献
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湖北省巴东县新城区滑坡灾害空间预测 总被引：1，自引：0，他引：1
论文在综合分析巴东县新城区区域地质背景及滑坡基本特征的基础上,分析了影响滑坡灾害发生的各因素与滑坡发生之间的相关性,提出影响灾害发生的主要因素：地形坡度、斜坡形态、岩性、构造、水的作用、人类工程活动。利用GIS的空间分析功能将各因素图件栅格化为86216个不规则单元。基于逻辑回归的方法对滑坡灾害进行了定量的概率预测。同时,对研究区进行滑坡灾害空间预测分区,将预测结果与该地区历史滑坡灾害发生情况进行对比发现预测精度为85．71％。说明所建立的模型具有较高的预测精度,是可以用于预测分析的。 相似文献
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基于GIS技术,利用信息量模型开展区域滑坡灾害危险性预测研究,编制滑坡灾害易发分区图,为滑坡灾害的风险预测及实时预警预报提供基础资料。以浙江省永嘉县为例,利用MAPGIS二次开发得到的信息量专业模块,结合永嘉县历史滑坡灾害和2004年以来新发生的灾害点,分别评价了研究区的历史滑坡灾害危险性和现状滑坡灾害危险性;提出用历史滑坡灾害危险性图件结合新发生的灾害点来验证评价模型;将历史灾害点和新灾害点结合生成滑坡灾害危险性预测图件的预测过程;研究成果经在永嘉县的实际验证分析,2004年后3次台风期间（2004年的“云娜” 台风,2005年的“海棠”和“麦莎”台风）发生的有准确地点的滑坡灾害点全部位于滑坡灾害易发区内,表明采用的模型具有较好的实用性和可靠性;采用历史统计和快速聚类相结合的方法进行危险性等级的划分,克服了前人研究工作中人为划分易发区的缺陷,更科学、客观。 相似文献
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溃坝洪水演进模拟的准确性是制约水库洪水预演有效性的关键。基于光滑粒子流体动力学(Smoothed Particle Hydrodynamics, SPH)方法提出了适用于溃坝洪水演进分析的数值模拟方法。通过设置溃口粒子与粒子库,基于黎曼不变量对SPH粒子状态进行修正,构建施加边界条件的改进SPH溃坝洪水演进模型,将SPH瞬时全溃整体模型转换为考虑溃口水流变化的入流边界模型,实现SPH方法与溃口计算模型的耦合。以Malpasset溃坝事件为例,检验了该模型计算溃坝洪水的精度,结果表明该模型精度相对较高,与实测值吻合较好;应用该模型模拟了某水库溃坝洪水演进预演过程,评估其对下游输水干渠及交叉建筑物排水倒虹吸的洪水冲击风险,结果表明在上游水库遭遇超标准洪水漫顶溃坝工况下,洪水演进至排水倒虹吸处的最大洪水位未超过校核洪水位。改进SPH模型精度高,可靠性强,与溃口计算模型耦合性好,可作为溃坝洪水演进模拟的通用手段之一。 相似文献
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滑坡周期项位移的预测,是研究地质灾害中滑坡变形至关重要的一步。由于单一模型易受偶然因素影响,且无法充分利用有效信息,导致其预测精度不高,适用性不强。基于此,文中提出了一种结合自适应粒子群算法（APSO）、支持向量机回归算法（SVR）、门控神经网络算法(GRU)的组合模型。该模型通过自适应粒子群优化算法对支持向量机回归算... 相似文献
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《岩土力学》2017,(4):1226-1232
采用光滑粒子流体动力学(SPH)方法和离散单元法(DEM),并基于达西渗透试验原理,提出一种SPH-DEM耦合算法用于处理宏观尺度下离散体与流体之间的相互作用问题,并基于该流-固耦合方法采用FORTRAN语言建立滑坡涌浪数学模型。模拟了块体滑坡问题,并与试验数据进行对比以验证该耦合方法的有效性。模拟分析了离散体滑坡产生涌浪以及涌浪传播的过程,分析比较了数值模拟得到的最大涌浪高度与经验公式结果间的关系。研究表明:采用该耦合方法模拟水下块体滑坡问题得到的结果与试验数据吻合良好;模拟离散体滑坡涌浪问题时,较清晰地反映了滑坡体对水的排挤到涌浪的产生过程、水在滑坡体中的渗透过程和滑坡体与水耦合作用发生变形的过程;不同公式分析方法得到的最大涌浪高度之间均有一定差别,算例中滑坡体受重力作用沿倾斜坡面滑动入水过程更接近于潘家铮法的垂直运动模式,因此,模拟结果与之最为接近。 相似文献
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光滑粒子流体动力学（SPH）是近年来发展起来的一种纯拉格朗日无网格法,并因其在大变形领域内的优势而受到广泛关注。在进行滑坡大变形分析时,流动法则及剪胀角的选取对于边坡失稳后的运动特性有重要的影响。采用Fortran自行编写了基于SPH的边坡稳定性及失稳后大变形分析程序,然后通过2个经典的算例,讨论了不同流动法则及剪胀角的选取对滑坡大变形分析精度的影响。结果表明：（1）剪胀角的选取对土体失稳后的滑动距离有显著影响,随着剪胀角的增大,土体的滑动速度与距离呈明显增大趋势;（2）在关联性流动法则及非关联性流动法则? =1/2? （? 为剪胀角,? 为摩擦角）条件下,土体在大变形过程中会产生过度膨胀,且运动速度与距离要大于实际情况,而采用关联性流动法? =0时,对于非膨胀土可以得到比较令人满意的结果,但对于膨胀土体会使得运动速度和运动距离过小,不符合实际情况。建议在计算膨胀土大变形时,采用非关联性流动法则且适当考虑膨胀性（? =(0.1～0.2)? ）,可以得到较好的结果。 相似文献
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考虑海冰热力因素对其厚度、密集度的影响,在光滑质点流体动力学(SPH)基础上发展了一个海冰热力-动力数值模式。该模式既解决了传统欧拉有限差分法和质点网格法存在的数值扩散问题,同时弥补了光滑质点动力学海冰动力模式未考虑热力因素的不足,具有精确模拟冰缘线运动、计算精度高等优点。首先介绍了光滑质点流体动力学的基本原理,并对海冰生消的热力因素进行了分析,将影响冰厚和密集度的热力因素引入到光滑质点流体动力学的海冰动力模式中,得到该热力-动力模式的控制方程。应用该数值模式对渤海海冰进行了48 h数值模拟,得到了海冰厚度和速度矢量的分布规律;对JZ20-2海域的海冰厚度、冰内温度场分布以及热力因素的变化特性进行了讨论。数值模拟结果表明,该数值模式能够很好地适用于渤海海冰数值模拟,是一种有效的海冰数值模拟方法。 相似文献
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本构模型是描述泥石流流变特性的关键,也是决定其动力过程数值模拟准确性的核心问题之一。泥石流流体属多相混合物,现有的研究已证实其存在剪切增稠或剪切变稀的现象,传统基于Bingham及Cross线性本构关系的数值模型难以准确描述泥石流流变特性。文中探讨了Bingham模型在低剪应变率下的数值发散问题,在光滑粒子流体动力学（SPH）方法框架上建立了整合Herschel-Bulkley-Papanastasiou(HBP）本构关系的稀性泥石流动力过程三维数值模型。相比传统基于浅水波假设的二维数值模型,所述方法从三维尺度建立SPH形式下的泥石流浆体纳维?斯托克斯方程并进行数值求解,可获取泥石流速度场时空分布及堆积形态,同时采用HBP本构关系描述泥石流流变特性,能在确保数值收敛的前提下反映泥石流流体在塑性屈服过渡段及大变形状态下应力?应变的非线性变化。为验证提出方法的合理性,结合小型模型槽实验观测进行了对比,结果表明数值模拟与实测结果基本吻合。 相似文献
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Simulation of large deformation and post‐failure of geomaterial in the framework of smoothed particle hydrodynamics (SPH) are presented in this study. The Drucker–Prager model with associated and non‐associated plastic flow rules is implemented into the SPH code to describe elastic–plastic soil behavior. In contrast to previous work on SPH for solids, where the hydrostatic pressure is often estimated from density by an equation of state, this study proposes to calculate the hydrostatic pressure of soil directly from constitutive models. Results obtained in this paper show that the original SPH method, which has been successfully applied to a vast range of problems, is unable to directly solve elastic–plastic flows of soil because of the so‐called SPH tensile instability. This numerical instability may result in unrealistic fracture and particles clustering in SPH simulation. For non‐cohesive soil, the instability is not serious and can be completely removed by using a tension cracking treatment from soil constitutive model and thereby give realistic soil behavior. However, the serious tensile instability that is found in SPH application for cohesive soil requires a special treatment to overcome this problem. In this paper, an artificial stress method is applied to remove the SPH numerical instability in cohesive soil. A number of numerical tests are carried out to check the capability of SPH in the current application. Numerical results are then compared with experimental and finite element method solutions. The good agreement obtained from these comparisons suggests that SPH can be extended to general geotechnical problems. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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固液耦合作用是碎屑流向泥石流转化形成复合型滑坡灾害的关键因素, 会导致成灾范围和规模放大, 是防灾减灾领域研究中的热点和难点问题之一。文中采用自主研发的滑坡后破坏数值模拟平台(LPF3D, Landslides post failure 3D), 以2014年9月强降雨诱发的重庆奉节无山坪滑坡为例, 探讨了滑坡在水动力作用下远程成灾的动力过程, 揭示了固液耦合影响机制。研究结果显示: 水动力作用在滑坡运动过程中主要体现为液化和拖曳两种, 两种力学作用的增程效应明显, 往往使得碎屑流转化为泥石流, 导致远程成灾; 基于光滑粒子流体动力学(SPH)方法的两相耦合计算模型, 考虑流体状态方程、固体黏塑性本构方程和相间作用力的共同影响, 基本还原了强降雨条件下重庆奉节无山坪滑坡两相运动过程; 数值计算结果显示无山坪滑坡最大运动速度为34 m/s, 最大堆积厚度为21.5 m, 堆积面积为0.12 km2, 最远运动距离为1300 m, 模拟结果同实际滑坡的堆积形态基本一致。综上认为, 在高位远程滑坡风险调查与预测过程中, 需充分考虑强降雨工况下孔隙水压力和固液相间作用, 基于LPF3D方法的数值模拟为高位远程滑坡的风险定量评估提供了依据。 相似文献
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A Lagrangian particle‐based method, smooth particle hydrodynamics (SPH), is used in this paper to model the flow of self‐compacting concretes (SCC) with or without short steel fibres. An incompressible SPH method is presented to simulate the flow of such non‐Newtonian fluids whose behaviour is described by a Bingham‐type model, in which the kink in the shear stress vs shear strain rate diagram is first appropriately smoothed out. The viscosity of the SCC is predicted from the measured viscosity of the paste using micromechanical models in which the second phase aggregates are treated as rigid spheres and the short steel fibres as slender rigid bodies. The basic equations solved in the SPH are the incompressible mass conservation and Navier–Stokes equations. The solution procedure uses prediction–correction fractional steps with the temporal velocity field integrated forward in time without enforcing incompressibility in the prediction step. The resulting temporal velocity field is then implicitly projected on to a divergence‐free space to satisfy incompressibility through a pressure Poisson equation derived from an approximate pressure projection. The results of the numerical simulation are benchmarked against actual slump tests carried out in the laboratory. The numerical results are in excellent agreement with test results, thus demonstrating the capability of SPH and a proper rheological model to predict SCC flow and mould‐filling behaviour. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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Shaohan Zhao Ha H. Bui Vincent Lemiale Giang D. Nguyen Felix Darve 《国际地质力学数值与分析法杂志》2019,43(5):1005-1031
In this paper, a new approach to applying confining stress to flexible boundaries in the smoothed particle hydrodynamics (SPH) method is developed to facilitate its applications in geomechanics. Unlike the conventional SPH methods that impose confining boundary conditions by creating extra boundary particles, the proposed approach makes use of kernel truncation properties of SPH approximations that occur naturally at free-surface boundaries. Therefore, it does not require extra boundary particles and, as a consequence, can be utilised to apply confining stresses onto any boundary with arbitrary geometry without the need for tracking the curvature change during the computation. This enables more complicated problems that involve moving confining boundaries, such as confining triaxial tests, to be simulated in SPH without difficulties. To further enhance SPH applications in elasto-plastic computations of geomaterials, a robust numerical procedure to implement Mohr-Coulomb plasticity model in SPH is presented for the first time to avoid difficulties associated with corner singularities in Mohr-Coulomb model. The proposed approach was first validated against two-dimensional finite element (FE) solutions for confining biaxial compression tests to demonstrate its predictive capability at small deformation range when FE solutions are still valid. It is then further extended to three-dimensional conditions and utilised to simulate triaxial compression experiments. Simulation results predicted by SPH show good agreement with experiments, FE solutions, and other numerical results available in the literature. This suggests that the proposed approach of imposing confining stress boundaries is promising and can handle complex problems that involve moving confining boundary conditions. 相似文献
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Liquefaction can result in the damage or collapse of structures during an earthquake and can therefore be a great threat to life and property. Many site investigations of liquefaction disasters are needed to study the large-scale deformation and flow mechanisms of liquefied soils that can be used for performance assessments and infrastructure improvement. To overcome the disadvantages of traditional flow analysis methods for liquefied soils, a soil–water-coupled smoothed particle hydrodynamics (SPH) modeling method was developed to analyze flow in liquefied soils. In the proposed SPH method, water and soil were simulated as different layers, while permeability, porosity, and interaction forces could be combined to model water-saturated porous media. A simple shear test was simulated using the SPH method with an elastic model to verify its application to solid phase materials. Subsequently, the applicability of the proposed SPH modeling method to the simulation of interaction forces between water and soil was verified by a falling-head permeability test. The coupled SPH method produced good simulations for both the simple shear and falling-head permeability tests. Using a fit-for-purpose experimental apparatus, a physical flow model test of liquefied sand has been designed and conducted. To complement the physical test, a numerical simulation has been undertaken based on the soil–water-coupled SPH method. The numerical results correspond well with the physical model test results in observed configurations and velocity vectors. An embankment failure in northern Sweden was selected so that the application of the soil–water-coupled SPH method could be extended to an actual example of liquefaction. The coupled SPH method simulated the embankment failure with the site investigation well. They have also estimated horizontal displacements and velocities, which can be used to greatly improve the seismic safety of structures. 相似文献
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空间三维滑坡敏感性分区工具及其应用 总被引：1，自引：0，他引：1
对于滑坡敏感性分区目前有三种方法:定性法、统计法和基于岩土定量模型的确定性方法。定性法基于对滑坡敏感性或灾害评估的人为判断;统计法用一个来源于结合了权重因子的预测函数或指标;而确定性法,或者说是物理定量模型法以质量、能量和动量守恒定律为基础。二维确定性模型广泛用于土木工程设计,而无限边坡模型(一维)也用于滑坡灾害分区的确定性模型。文中提出了一个新的基于GIS(地理信息系统)的滑坡敏感性分区系统,这个系统可用于从复杂地形中确认可能的危险三维(3-D)滑坡体。所有与滑坡相关的空间数据(矢量或栅格数据)都被集成到这个系统中。通过把研究区域划分为边坡单元并假定初始滑动面是椭球的下半部分,并使用Monte Carlo随机搜索法,三维滑坡稳定性分析中的三维最危险滑面是三维安全系数最小的地方。使用近似方法假定有效凝聚力、有效摩擦角和三维安全系数服从正态分布,可以计算出滑坡失稳概率。3DSlopeGIS是一个计算机程序,它内嵌了GIS Developer kit(ArcObjects of ESRI)来实现GIS空间分析功能和有效的数据管理。应用此工具可以解决所有的三维边坡空间数据解问题。通过使用空间分析、数据管理和GIS的可视化功能来处理复杂的边坡数据,三维边坡稳定性问题很容易用一个友好的可视化图形界面来解决。将3DSlopeGIS系统应用到3个滑坡敏感性分区的实例中:第一个是一个城市规划项目,第二个是预测以往滑坡灾害对临近区域可能的影响,第三个则是沿着国家主干道的滑坡分区。基于足够次数的Monte Carlo模拟法,可以确认可能的最危险滑坡体。这在以往的传统边坡稳定性分析中是不可能的。 相似文献
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文章简要评述了地质灾害基础理论与应用技术发展现状、滑坡灾害多种监测预报判据的利弊。利用综合信息处理决策方法,提出了基于权变理论的滑坡灾害监测预报新思路。分析了滑坡成灾的权变特征、环境因素和决策因素,建立了滑坡灾害预报决策概念模型。进一步探讨了在预报决策中应遵循的动态性及满意性原则,为提高地质灾害监测预报理论的科学性提供了新的理论依据与技术途径。 相似文献