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Status and Trends in Research on Deep-Water Gravity Flow Deposits

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Acta Geologica Sinica(English Edition) 2015年第2期89卷 610-631页

作者： YANG Tian CAO Yingchang WANG Yanzhong LI Ya ZHANG Shao Min School of Geosciences China University of Petroleum (East China)

Deep-water gravity flows are one of the most important sediment transport mechanisms on Earth. After 60 years of study, significant achievements have been made in terms of classification schemes, genetic mechanisms, and depositional models of deep-water gravity flows. The research history of deep-water gravity flows can be divided into five stages： incipience of turbidity current theory; formation of turbidity current theory; development of deep-water gravity flow theory; improvement and perfection of deep-water gravity flow theory; and comprehensive development of deep-water gravity flow theory. Currently, three primary classification schemes based on the sediment support mechanism, the rheology and transportation process, and the integration of sediment support mechanisms, rheology, sedimentary characteristics, and flow state are commonly *** types of deep-water gravity flow events form different types of gravity flow deposits. Sediment slump retransportation mainly forms muddy debris flows, sandy debris flows, and surge-like turbidity currents. Resuspension of deposits by storms leads to quasi-steady hyperpycnal turbidity currents （hyperpycnal flows）. Sustainable sediment supplies mainly generate muddy debris flows, sandy debris flows, and hyperpycnal flows. Deep-water fans, which are commonly controlled by debris flows and hyperpycnal flows, are triggered by sustainable sediment supply; in contrast, deep-water slope sedimentary deposits consist mainly of debris flows that are triggered by the retransportation of sediment slumps and deep-water fine-grained sedimentary deposits are derived primarily from fine- grained hyperpycnal flows that are triggered by the resuspension of storm deposits. Harmonization of classification schemes, transformation between different types of gravity flow deposit, and monitoring and reproduction of the sedimentary processes of deep-water gravity flows as well as a source-to-sink approach to document the evolution and depo

关键词： Development history turbidity debris flows deep-water gravity flows genesis,depositional model

Comparative Study on debris Flow Initiation in Limestone and Sandstone Spoil

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Journal of Mountain Science 2013年第2期10卷 190-198页

作者： CHEN Ning-sheng LU Yang DENG Ming-feng HAN Da-wei ZHOU Hai-bo YANG Cheng-lin Key lab of mountain hazards and surface process Institute of mountain hazards and environmentChinese Academy of Sciences University of Chinese Academy of Sciences University of Bristol UK

Large spoil tips from reconstruction works as a result of the Wenchuan Earthquake in China are new debris flow hazards to the human ***,there is a lack of detailed comparative study on debris flow initiation in different spoil *** paper describes a series of tests and analyses on debris flow characteristics(initiation,scale and mechanism) at six sites with limestone and sandstone materials near the Dujiangyan *** shows the limestone spoil contains debris flow prone clay content with high concentration of montmorillonite(highly expandable).In addition,limestone spoil is of such a low permeability that water mainly concentrates in the upper surface *** factors make it easy for the increase of pore water pressure,decline of internal friction and conhesion force,leading to the occurence of large debris *** contrast,the sandstone spoil is less problematic and causes no major debris flow *** on our research on the mechanism,the"stereometric drainage"method is sucessfully applied to control limestone spoil debris flows.

关键词： debris flows Comparative study Reconstruction spoil Initiation mechanism Mitigation measures

Effect of clay content to the strength of gravel soil in the source region of debris flow

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Journal of Mountain Science 2018年第10期15卷 2320-2334页

作者： CHEN Ning-sheng GAO Yan-chao Yang Cheng-lin HU Gui-sheng Key Laboratory of Mountain Hazards and Land Surface Process Institute of Mountain Hazards and EnvironmentCASChengdu 60041China Chengdu Center China Geological SurveyChengdu 610081China University of Chinese Academy of Sciences Beijing 100049China

The production of runoff in the source area of a debris flow is the consequence of a reduction in soil strength. Gravel soil is widely distributed in the source region, and the influence of its clay content on soil strength is one of the important questions regarding the formation mechanism of debris flows. In this paper, the clay content in gravel soil is divided into groups of low clay content(1%, 2, 5%), moderate clay content(3.75%, 5.00%, 6.25%, 7.5%) and high clay content(10.0%, 12.5%, 15%). Tests of the unconsolidated undrained shear strength and consolidated drained shear strength were performed. The unconsolidated undrained shearing(UU) experiment simulates the rapid shear failure of loose gravel soil under the conditions of brief heavy rainfall. The consolidated drained shearing(CD) experiment simulates creep failure of consolidated sediment during extended rainfall. The pore water pressure first increased and then decreased as the clay content increased, and the increase in pore pressure was relatively high in the gravel soil sample when the clay content is in the range of 3.25-7.50%, and stress in the gravel soil is relatively low for a moderate clay content. Gravelly soils with a moderate clay content are moreprone to debris-flow initiation. This paper presents a mathematical formula for the maximum shear stress and clay content of gravel soil under two conditions. The key processes whereby the soil fails and triggers a debris flow—volume contraction of soil, expansion of clay soil, and rise of pore pressure―cause reductions in the soil friction force and enhancement of the water content in the clay particles, and subsurface erosion of soil reduces the soil viscosity, which eventually reduces the soil strength so that the soil loses its stability, liquefies and generates a debris flow.

关键词： debris flows Gravel soil Clay content Maximum shear stress Pore water pressure

Mutual Interference of Two debris Flow Deposits Delivered in a Downstream River Reach

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Journal of Mountain Science 2014年第6期11卷 1385-1395页

作者： STANCANELLI Laura Maria LANZONI Stefano FOTI Enrico Department of Civil Engineering and Architecture University of Catania Department of Civil Environmental and Architectural Engineering University of Padua

We investigate experimentally the depositions of two contiguous debris flows flowing into a main river *** aim of the present experimental research is to analyze the geometry and the mutual interactions of debris flow deposits conveyed by these tributaries in the main channel.A set of 19 experiments has been conducted considering three values of the confluence angle,two slopes of the tributary,and three different triggering conditions(debris flows occurring simultaneously in the tributaries,or occurring first either in the upstream or in the downstream tributary).The flow rate along the main channel was always kept *** each experiment the two tributaries had the same slope and confluence *** analysis of the data collected during the experimental tests indicates that the volume of the debris fan is mainly controlled by the slope angle,as expected,while the shape of the debris deposit is strongly influenced by the confluence ***,in the case of multiple debris flows,the deposit shape is sensitive to the triggering *** index for damming formation available in literature has been considered and applied to the present case,and,on the basis of the collected data,considerations about possible extension of such indexes to the case of multiple confluences are finally proposed.

关键词： debris flows Confluences Dam formation Triggering scenario Critical Index

Mitigation measures of debris flow and landslide risk carried out in two mountain areas of North-Eastern Italy

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Journal of Mountain Science 2022年第6期19卷 1808-1822页

作者： GENEVOIS Rinaldo TECCA Pia Rosella GENEVOIS Clervie Padua University Vicolo Mazzini 18Padova 35137Italy CNR-IRPI Corso Stati Uniti 4Padova 35127Italy SINPRO s.r.l. Via deWArtigianato 20Vigonovo(VE)30030Italy

The design of remediation works for the mitigation and prevention of the associated risk is needed where these geological hazards affect anthropized areas. Remedial measures for landslides commonly include slope reshaping, plumbing, drainage, retaining structures and internal slope reinforcement, while debris flow control works consist in open or closed control structures. The effectiveness of the remedial works implemented must be assessed by evaluating the reduction of the risk over time. The choice of the most appropriate and cost-effective intervention must consider the type of hazard and environmental issues, and selects, wherever possible, naturalistic engineering operations that are consequently implemented according to the environmental regulations or the design and specification standards imposed by the competent public administrations. The mitigation procedures consist of five basic steps:(a) acquisition of the knowledge of the hazard process;(b) risk assessment with identification of possible disaster scenarios;(c) planning and designing of specific remedial measures to reduce and/or eliminate the potential risk;(d) slope monitoring after application of remedial measures,(e) transfer of knowledge to the stakeholders. This paper presents two case studies describing the practice for the design of the mitigation measures adopted for debris flow and active landslide sites in North-Eastern Italy. The first case study is a debris flow site, for which, based on observation of past events and numerical simulations using the software FLOW-2D, the most suitable mitigation measures were found to be the construction of a debris basin, barriers and breakers. The second case study deals with an active landslide threatening a village. Based on the landslide kinematics and the results of numerical simulations performed with the code FLAC, hard engineering remedial works were planned to reduce the driving forces with benching and by increasing the available resisting forc

关键词： debris flows Landslides Geological hazards Mitigation measures FLO-2D FLAC

Geomorphic evidence of ancient catastrophic flow type landslides in the mid-mountain ridges of the Western Flysch Carpathian Mountains(Czech Republic)

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International Journal of Sediment Research 2009年第1期24卷 88-98页

作者： T. PNEK J. HRADECKY K. ILHN Assoc. University of Ostrava Faculty of Science Department of Physical Geography and Geoecology Chittussiho 10 71000 Ostrava Czech Republic University of Ostrava Faculty of Science Department of Physical Geography and Geoecology Chittussiho 10 71000 Ostrava Czech Republic

Ancient flow type landslides are relatively frequent fossil forms of the relief in mid-mountain conditions of the Czech Carpathian Mountains. Sixty rather distinctive displays of debris flows,rock avalanches,and debris avalanches have been mapped in the uppermost part of the territory. Unlike contemporary sporadic and low volume debris flows,ancient(Pleistocene and Lower Holocene) accumulations are a few orders of magnitude more extensive and were of considerable geomorphologic significance in forming the steep sections of mountain valleys and slopes. This geomorphic pattern does not hold for flow type slides,the source of which is material released as a consequence of numerous deep-seated landslides. Due to deep disruption of slopes,a few high-magnitude flow type landslides(e.g.,rock avalanches),quite rare in flysch mid-mountain conditions,also occurred in the Late Holocene.

关键词： debris flows Rock avalanches Deep-seated landslides Flysch Western Carpathian Mountains

Using Fuzzy Relations and GIS Method to Evaluate debris Flow Hazard

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Wuhan University Journal of Natural Sciences 2006年第4期11卷 875-881页

作者： SONG Shujun ZHANG Baolei FENG Wenlan ZHOU Wancun Institute of Mountain Hazards and Environment Chinese Academy of SciencesChengdu 610041SichuanChina Graduate University of Chinese Academy of Sciences Beijing 100049China

The study area, located in the southeast of Tibet along the Sichuan-Tibet highway, is a part of Palongzangbu River basin where mountain hazards take place frequently. On the ground of field surveying, historical data and previous research, a total of 31 debris flow gullies are identified in the study area and 5 factors are chosen as main parameters for evaluating the hazard of debris flows in this study. Spatial analyst functions of geographic information system （GIS） are utilized to produce debris flow inventory and parameter maps. All data are built into a spatial database for evaluating debris flow hazard. Integrated with GIS techniques,the fuzzy relation method is used to calculate the strength of relationship between debris flow inventory and parameters of the database. With this methodology,a hazard map of debris flows is produced. According to this map,6.6% of the study area is classified as very high hazard, 7.3% as high hazard,8.4% as moderate hazard,32. 1% as low hazard and 45.6% as very low hazard or non-hazard areas. After validating the results, this methodology is ultimately confirmed to be available.

关键词： fuzzy relations geographic information system (GIS) debris flows hazard evaluation

A study on the early-warning technique concerning debris flow disasters

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Journal of Geographical Sciences 2002年第3期12卷 363-370页

作者： ZHOU Jinxing, WANG Lixian, XIE Baoyuan, FEI Shimin, WANG Xilin (1. Inst. of Forestry Research, Chinese Academy of Forestry Science, Beijing 100091, China 2. College of Resource & Environment, Beijing Forestry University, Beijing 100083, China) Inst. of Forestry Research Chinese Academy of Forestry Science Beijing China College of Resource & Environment Beijing Forestry University Beijing China

According to the principle of the eruption of debris flows, the new torrent classification techniques are brought forward. The torrent there can be divided into 4 types such as the debris flow torrent with high destructive strength, the debris flow torrent, high sand-carrying capacity flush flood torrent and common flush flood by the techniques. In this paper, the classification indices system and the quantitative rating methods are presented. Based on torrent classification, debris flow torrent hazard zone mapping techniques by which the debris flow disaster early-warning object can be ascertained accurately are identified. The key techniques of building the debris flow disaster neural network (NN) real time forecasting model are given detailed explanations in this paper, including the determination of neural node at the input layer, the output layer and the implicit layer, the construction of knowledge source and the initial weight value and so on. With this technique, the debris flow disaster real-time forecasting neural network model is built according to the rainfall features of the historical debris flow disasters, which includes multiple rain factors such as rainfall of the disaster day, the rainfall of 15 days before the disaster day, the maximal rate of rainfall in one hour and ten minutes. It can forecast the probability, critical rainfall of eruption of the debris flows, through the real-time rainfall monitoring or weather forecasting. Based on the torrent classification and hazard zone mapping, combined with rainfall monitoring in the rainy season and real-time forecasting models, the debris flow disaster early-warning system is built. In this system, the GIS technique, the advanced international software and hardware are applied, which makes the system’s performance steady with good expansibility. The system is a visual information system that serves management and decision-making, which can facilitate timely inspect of the variation of the torrent type

关键词： debris flows disaster early-warning technique torrent classification mapping of the hazard zones

Early Holocene High Magnitude debris Flow Events and Environmental Change as Illustrated by the Moxi Platform, Hengduan Mountains, SW China

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Journal of Mountain Science 2006年第2期3卷 125-130页

作者： ZHANG Junyan CHENG Genwei LI Yongfei Institute of Mountain Hazards and Environment Chinese Academy of Sciences Chengdu 610041 China Graduate University of Chinese Academy of Sciences Beijing 100049 China Department of Biology Acadia University Wolfville Nova Scotia Canada B4P 2R6 Department of Geography Shangrao Normal College Shangrao 334001 Jiangxi China

Thick debris flow deposits in the Hengduan Mountains of southwestern China record landscape instability at the close of the last glaciation and in the early Holocene. The deposits, ranging in thickness from 100 to 200 m, are common and in high magnitude in the valleys of this region. They are products of large debris flows induced by glacier and enabled by the presence of large amount of glacial debris on the landscape. The carbon 14 dating from Moxi Platform indicates that a period of catastrophic debris flows occurred at c. 7 kyr B.P., and was concurrent with other glacial-fluvial fans and terraces which tied to regional climatic oscillations elsewhere in the Himalaya. The comparable events suggest a strong climatic control on earth surface processes for the dynamics, magnitude, and frequency in this region.

关键词： debris flows environment change Holocene Hengduan Mountains China