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Cell-based methodologies for rainfall-induced landslide and debris-flow risk assessment and early warning.

机译：基于单元的方法对降雨引起的滑坡和泥石流风险进行评估和预警。

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摘要

The 12 May 2008 Wenchuan earthquake triggered numerous landslides. A large number of additional slope failures and debris flows were triggered by storms in the last several years after the earthquake. Since a large amount of loose materials is still retained on the steep terrains, widespread slope failures and debris flows are likely to occur in the future. Hence, appropriate methods are needed for hazard analysis, risk assessment, and early warning for regional rainfall-induced slope failures and debris flows. The risks to travellers posed by slope failures and debris flows along an 18 km section of Provincial Road 303 (PR303) near the epicentre of the Wenchuan earthquake are considered in this thesis research.;Numerous hazardous soil deposits are distributed in the study area at high elevations up to 2000 m above the road. A real-time distributed risk-based early warning system based on monitored rainfall by rain gauges is developed to safeguard the travellers on the road. The system accommodates several types of landslide hazards, particularly uncertain and inaccessible hazards, and is robust and cost-effective. The early warning system comprises six components; namely, a digital terrain module, a spatial rainfall distribution module, a slope failure prediction module, a debris flow simulation module, a multi-hazard quantitative risk assessment module, and a warning message issuing module. Given monitored rainfall data, the temporal and spatial response of the digital terrain to rainfall can be analysed by the slope prediction module and the debris flow simulation module. The multi-hazard quantitative risk assessment module evaluates the temporal and spatial risks posed by the slope failures and debris flows. The 18 km road is divided into 18 sections, one kilometre each, and each section is a warning entity. The warning level for each road section is determined based on the sectional average individual risk.;A physically-based distributed cell model for predicting regional rainfall-induced slope failures and runout on three-dimensional digital terrain is developed in this thesis research, which forms the slope failure prediction module for the early warning system. The model can predict the locations, volumes, runout traces, and deposition locations of the slope failures efficiently. Since soils are layered at some locations, an infiltration analysis module for slopes with two-layer soils under arbitrary rainfall conditions is developed. Empirical equations that are developed based on a slope failure inventory in the study area are adopted as runout cessation criteria. The size effect of slope failures and uncertainties in shear strength parameters and the runout process are considered in the runout prediction.;A new depth-integrated numerical model for simulating debris flow (EDDA) is developed, which forms the debris flow simulation module for the early warning system. The model considers the changes in debris flow density, yield stress, and dynamic viscosity, as well as the influences of such changes on the runout characteristics of the debris flow. The yield stress of the debris flow mixture estimated using the Mohr-Coulomb equation is suitable for any of clear water flow, hyper-concentrated flow, and fully developed debris flow. A variable time step algorithm is developed to assure both numerical stability and computation efficiency. The model is able to simulate two-dimensional dam-break water flows, confined debris flows in a channel, unconfined debris flows in a flat area and catchment-scale debris flows considering erosion, deposition and property changes.;A multi-hazard quantitative risk assessment (QRA) method for slope failures and debris flows has been developed, which forms the multi-hazard quantitative risk assessment module for the early warning system. The method quantitatively assesses the risk posed by regional slope failures and debris flows and the influence of slope failures on debris flows. Both individual risk and societal risk are assessed. The integrated QRA for slope failures and debris flows also considers the scenario of a location being impacted by several slope failures or debris flows or both. The method is applied to the study area and verified by the slope failures and debris flows triggered by the 13 August 2010 storm. The established early warning system is able to cover the 165 km2 study area efficiently, and proves to be a valuable tool for mitigating the risks posed by regional slope failures and debris flows.
机译：2008年5月12日的汶川地震引发了无数次滑坡。地震后的最近几年中，暴风雨引发了许多其他的边坡破坏和泥石流。由于仍然在陡峭的地形上保留了大量的松散材料，因此将来很可能会发生广泛的边坡破坏和泥石流。因此，需要适当的方法进行危害分析，风险评估以及区域降雨引起的边坡破坏和泥石流的预警。本文研究了汶川地震震中附近省道303号公路（PR303）沿18公里路段的边坡破坏和泥石流对旅行者造成的风险。海拔最高可达道路上方2000 m。开发了基于雨量计监测降雨的实时分布式风险预警系统，以保护道路上的旅行者。该系统可容纳多种类型的滑坡灾害，特别是不确定和难以接近的灾害，并且功能强大且具有成本效益。预警系统包括六个部分。包括数字地形模块，空间降雨分布模块，边坡破坏预测模块，泥石流模拟模块，多灾种定量风险评估模块和警告消息发布模块。给定监控的降雨数据，斜率预测模块和泥石流模拟模块可以分析数字地形对降雨的时间和空间响应。多危害定量风险评估模块可评估边坡破坏和泥石流带来的时空风险。 18公里的道路分为18个路段，每个路段1公里，每个路段都是一个警告实体。根据断面平均个人风险确定每个路段的预警水平。；本研究建立了一种基于物理的分布式单元模型，用于预测区域降雨引起的边坡破坏和三维数字地形的跳动，形成了预警系统的边坡破坏预测模块。该模型可以有效地预测边坡破坏的位置，体积，径迹和沉积位置。由于土壤在某些位置分层，因此开发了在任意降雨条件下具有两层土壤的边坡的入渗分析模块。根据研究区域的边坡破坏清单开发的经验方程式被用作跳动停止标准。在跳动预测中考虑了边坡破坏的大小效应以及抗剪强度参数和跳动过程的不确定性。；建立了一个新的深度综合数值模拟泥石流的模型（EDDA），形成了泥石流的模拟模型。预警系统。该模型考虑了泥石流密度，屈服应力和动态粘度的变化，以及这些变化对泥石流跳动特性的影响。使用Mohr-Coulomb方程估算的泥石流混合物的屈服应力适用于清澈的水流，超浓缩流和充分发育的泥石流。开发了可变时间步长算法，以确保数值稳定性和计算效率。该模型能够模拟二维溃坝水流，河道中的受限碎屑流，平坦区域中的无限制碎屑流以及考虑侵蚀，沉积和性质变化的集水规模碎屑流;多危害定量风险已经开发了边坡破坏和泥石流评估方法（QRA），形成了预警系统的多危害定量风险评估模块。该方法定量评估了区域性边坡破坏和泥石流带来的风险以及边坡破坏对泥石流的影响。评估个人风险和社会风险。针对斜坡破坏和泥石流的集成QRA还考虑了位置受多个斜坡破坏或泥石流或两者影响的情况。该方法已应用于研究区域，并通过2010年8月13日暴风雨引发的边坡破坏和泥石流进行了验证。既定的预警系统能够有效覆盖165平方公里的研究区域，并被证明是减轻区域斜坡失稳和泥石流带来的风险的宝贵工具。

著录项

  • 作者

    Chen, Hongxin.;

  • 作者单位

    Hong Kong University of Science and Technology (Hong Kong).;

  • 授予单位 Hong Kong University of Science and Technology (Hong Kong).;
  • 学科 Civil engineering.
  • 学位 Ph.D.
  • 年度 2015
  • 页码 322 p.
  • 总页数 322
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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