Mountain Disasters Research Articles

Effects of Excavation on Deformation and Failure of Anti-Dip Slopes under the Action of Seismic Load

Wenchuan earthquak induced a large number of mountain hazards. Through the survey found that manual excavation slopes tend to become concentrated area of mountain disaster, it’s indicate that the effect of excavation damage on the slope deformation and failure under seismic load is very obvious. Anti-dumping slope deformation as one types of mountain hazards induced by Wenchuan earthquake, and it’s also seriously affected by excavation damage. In this paper, as Wang Jiaping landslide for example, using the finite element method to simulate the landslide and analysis the deformation and failure of slope affected by the excavation damage. Analysis shows that deformation and failure of slope is significantly induced by excavation, and resulting in displacement, stress and the between layer sliding distance increased，the between layer friction stress reduced. The results agreement with the characteristics of the anti-dumping slope deformation and failure induced by Wenchuan earthquake mainly concentrated in excavation slopes.

Theoretical Reflection on Disaster Prevention and Reduction in Southwest Mountainous Cities

The disasters in southwest mountainous cities are serious and special, which has wide distribution range and whose relative factors are complicated and fuzzy. The paper analyses two categories, five terms characters of mountain disaster, which supported by statistics data. The relationship between mountain disasters and the construction are closeness. Disaster prevention and reduction to the human settlement construction is basic function, which needs theoretical support by human settlement.

Effects of Overburden on Deformation and Failure of Anti-Dip Slopes under the Action of Seismic Load

A large number of mountain disasters were induced by Wenchuan Earthquake, and as one type of them, the deformation and failure modes of anti-dip slopes were influenced by overburden. Under the condition of no overburden, the collapse will mainly occur; while under the overburden condition, it is the shallow slump mainly occured. Taking the landslide of Wangjia Mountain in Longmenshan Town, Pengzhou City as an example, the anti-dip slopes were stimulated by using the finite element method in this study, where the influences of overburden on deformation and failure of anti-dip slopes were analyzed under the static condition with seismic load effect. The related analysis showed that significant influences of overburden existed on the deformation and failure of slopes, resulting into great increments of slope displacement, stress and sliding distance. The analytical results were consistent with the characteristics that the large-scale deformation and failure of anti-dip slopes mainly occurred on the slopes with overburden in the Wenchuan Earthquake.

Voluntary Self-Help Organization and Fire Volunteer for Mountain Disaster Risk Reduction in Reihoku Area, Japan

Voluntary Self-Help Organization and Fire Volunteer for Mountain Disaster Risk Reduction in Reihoku Area, Japan

The subject of the mountainous disaster prevention in the Tohoku district

The subject of the mountainous disaster prevention in the Tohoku district

Rapid Assessment of Secondary Disasters Induced by the Wenchuan Earthquake

The Wenchuan earthquake of 12 May 2008 produced numerous secondary mountain disasters, including the formation of dangerous barrier lakes resulting from blocked river channels. By exploiting real-time, multiplatform remote sensing imagery data, researchers located these barrier lakes, acquired their distribution information, and assessed the threats to inform mitigation efforts and help prevent potentially disastrous consequences.

Close relationship between the frangibility of mountain eco-environment and mountain disasters: A case study of Dongchuan, Kunming in Yunnan Province

Anatomical details are given in this article, which is performed by investigating the relationship between through the frangibility of mountain eco-environment and the status of irrational land-use in typical region of debris flow in Dongchuan district, Kunming city, yunnan Province. This analysis is extended to the relationship between vicissitude of mountain disasters and the frangibility of mountain environment. The relatively coupling action of a vicious circle is a evolving characteristic by debris flow sand-gravel there. The eco-security is being faced with serious challenge. The tactics of eco-security has been constructed since 1980s. Thus, the eco-environment can gradually be repaired and optimized to achieve a fine circle.

Approaches to the environmental management of disasters in mountainous areas of China

SUMMARY Mountain disaster occurrence has a close relationship with human activities. It is the human activity that aggravates the mountain disasters and environment deterioration. Therefore, during the process of social and economic development, regulating human behaviour, reasonably utilizing and protecting natural resources and environment by means of controlling the human approach, i.e. industrial economy, regional economy allocation, river basin economy, scientific technology and population resettlement, are important approaches to the prevention and management of mountain disasters. The analysis of several cases in China shows that effective combination of civil engineering measures, bioengineering measures and human behaviour could play an important role in ensuring mountain disaster prevention and environmental sustainable develop ment. However, in the long run, prevention of mountain disasters and environmental deterioration is just regulating management of the human effect and human behaviour, but not civil engineering and bio-engineering measures. In 1994, the State Council, China, approved ‘China 21st Agenda’, that regarded disaster prevention and mitigation as important national policies with the goals of ensuring country, society, economy development, and confirmed decreasing nature human disaster losses as the total aim and action plan of country disaster prevention and mitigation management.

Critical hydrologic conditions for overflow burst of moraine lake

Floodwater and debris flow caused by glacial lake burst is an important land process and a serious mountain disaster in glacial area of Xizang (Tibet) Autonomous Region, and the overflow burst is mainly caused by glacial landslide falling into moraine lake. On the premise that moraine lake is full, instantaneous burst in part of the lake bank happens, as flow velocity at burst mouth caused by overflow head is higher than threshold flow velocity of glacial till. Under some supposes, d(90) and d(10) of the glacial till in the hank were used as the threshold sizes of coarse and fine grains respectively. Thus, the formula of calculating threshold flow velocity of uniform sand was simplified, and threshold flow velocity of glacial till was calculated with the formula. Then, with synthesis formula calculating flow velocity of instantaneous part burst, flow velocity at overflow burst mouth was calculated, and calculation formula of critical height (H(0)) of overflow head was derived. Overflow head was caused by volume and surge of glacial landslide falling into moraine lake, calculation formulas of ascendant height (H(1)) of lake water surface and surge height (H(2)) on burst mouth caused by glacial landslide falling into moraine lake were derived. To sum up, critical hydrologic conditions of moraine lake burst with overflow form are: the burst is inevitable as H(1) > H(0); the burst is possible as H(1) H(0); the burst is impossible as (H(1)+H(2)) < H(0). In the factors influencing the burst critical conditions, it is advantageous for the burst that scale of the lake is 10(5)m(2) range; terminal glacial till is more fine and is even more uniform; the width of overflow mouth is even smaller than the length of the bank; the landslide has large scale and steep slip surface; and glacial end is close to the lake. With burst of Guangxiecuo Lake in Midui Valley of the Polongzangbu River in Xizang as an example, the burst critical conditions were tested.

Differential distribution regularity of collapse-landslides and debris flows along Palong Zangbu River Valley in Tibet

Collapse-landslides and debris flows are main types of mountain disasters in Palong Zangbu river valley of Tibet. These disasters are large in scale and serious in harm-fulness to the valley. Differences of hydro-thermal conditions related to aspect of valley slope lead to differences distribution of the collapse-landslide and debris flows.Differences of the geomorphologic evolution and morphologic processes of the valley lead to distribution differences of the disasters along the river. Differences of growth conditions between collapse-landslides and debris flows lead to distribution differences of the two types of disasters. For control of mountain disasters and site selection of highways and railways along the river, distribution regularities of the collapse-landslides and debris flows with the above-mentioned differences are identified, by quantitative methods including orderly sample optimum cutting method and the variance analysis, method. These regularities are: (1) the whole river section (from Ranwu to Lulang) can be divided into: a) upstream gorge section with concentrateddistribution of debris flows, avalanches and debris cones; b) midstream broad valley section with more concentrated distribution of debris flows and collapse-landslides; and c)downstream gorge section and the tributary of Layue with extremely concentrated distribution of debris flows and collapse-landslides. (2) Quantities and scales of collapse-landslides and debris flows on the northern slope surpass those on the southern slope of the river valley. (3) The collapses and landslides have an increase tendency towards downstream and the debris flows have a decrease tendency in order of the downstream gorge section, the upstream gorge section and the midstream broad valley section. Further, some suggestions on site selection principle of road plane are advanced.

A Positive Research on the Channel Characteristics of the Hime River

In order to clear the channel characteristics of the Hime river, the history of the hydroelectric power development and the disaster were examined based on the consideration on the topography, the geology, and the disaster in 1995. In the Hime valley, a vast channel is clearly noticed on the mid-stream through the field investigation, it's considered that the channel characteristics are divided into several classes. As the results, the function as the sediment storage area of the vast channel on the mid-stream was confirmed. Furthermore, two follow in gcontribution of the existence of the channel characteristics were found: 1) For prevention of the deposited silt to the lower valley in the mountain disaster. 2) For stabilizing the main river-bed evolution for several years after the disaster.

Mountain disaster formation in northwest Sichuan

This paper discusses the causes of debris flow, landslide, collapse, water and soil erosion and other mountain disasters in the high mountain-plateau transitional region in northwest Sichuan. Through analysis of geological structure, lithology, earthquakes, landforms, hydrologic regime, meteorological conditions and man-made factors, the authors conclude that the natural conditions of this region favor the formation of debris flow, landslides and other mountain disasters. Moreover, the irrational economic activities of humans such as destroying forest ecosystems stimulate the occurrence of mountain disasters.

Landscape and quaternary climatic changes in eastern Tibet and surroundings

Co-operation between Chinese and German geo-scientists in Tibet and adjacentareas started in 1981 with the Sino-German Joint Expedition to the Northeastern part of the Qinghai-Xizang (Tibet) Plateau, led by Prof. Dr. Jtirgen H6vermann (G6ttingen) and Prof. Wang Wenying (Lanzhou/Xian). Later several further Sino-German Joint Expeditions were conducted in China. The editors had the opportunity of participating in one of these expeditions to Tibet in 1989 led by Prof. J. H6vermann and Prof. Li Jian (Chengdu). Based on this expedition further detailed investigations, especially in geomorphology, palaeoclimate and applied geomorphology along the eastern margin of the Tibetan Plateau, were made in summer 1991. In this volume results from this 1991 expedition (inside rectangle of Fig 1) as well as from the 1989 and 1992 expeditions (outside rectangle of Fig 1) are presented. The 1991 expedition was led by Prof. Tang Bangxing, Dr. Liu Shijian and Dr. F. Lehmkuhl, altogether six Chinese and two German scientists participated (including: Prof. Li Jian, Prof. Wang Chenghua, M. S. Li Lihua, M. S. Wang Yangchung and Dipl.-Geogr. B. Damm). Since 1989 there has also been close co-operation between the Institute of Geography of G6ttingen University, the Institute of Botany of Hohenheim University (Prof. Dr. Dr. B. Frenzel) and the Institute of Mountain Disasters & Environment (Chinese Academy of Sciences) in Chengdu. This group, too, has conducted an expedition in 1992, led by Prof. B. Frenzel and Prof. Tang Bangxing, in which the editors could also participate. The main investigation area of 1991 was the Nianbaoyeze Mountains and the adjacent areas at the margin of northwestern Sichuan Province and Qinghai. The highest peak of Nianbaoyeze (5369m) is about 800m above the surrounding peneplain. Pleistocene glacial landforms are well preserved, a few glaciers still exist. An introduction to physical geography with special reference to the Pleistocene glaciations in the eastern fringe of the Tibetan Plateau, of the Nianbaoyeze Mountains in particular, is presented by F. Lehmkuhl and Liu Shijian. Palaeo-surfaces and the history of the upper Huang He valley are analysed by F. Lehmkuhl and J. Sp6nemann. Mountain disasters were another goal of investigation. Tang Bangxing, Liu Suqing and Liu Shijian have studied debris flows and their distribution at the Minjiang throughout the catchment and in other regions in western Sichuan. Liu Shijian examines the impact of debris flows on quartz-grain surfaces, and discusses this method as a possibility to separate debris flow from morainic deposits. J. B6hner describes southeastern Tibet and the adjacent areas with respect to the varying climatic circulation. N. Niehoff contributes on the chemistry of the precipitation in this area (results of the 1992 expedition). A. Br/iuning presents observations from tree ring analysis (samples from the 1989, 1991 and 1992 expeditions) with regard to the climate of the historical period. The palaeoclimate of eastern Tibet is shown in a larger context with some results from Western and Central China. H. J. Pachur, B. W/.innemann, Linyuan Zhang, Hucai Zhang and Yuzheng Ma focus on floodplain sediments in the transition zone to the Loess Plateau near the divide between the Huang He and Yangtze river systems (see No. 1 in Fig 1). Finally, K.T. Rost focusses on palaeoclimate conditions of the Qinling Mountains and their foreland facing the Loess Plateau (No. 2 in Fig 1). The editors wish to express their sincere thanks to Prof. Dr. J. H6vermann for his effort to initiate these expeditions in Central Asia, for his support and for frequent stimulating discussions. We would like to thank not only the authors for their contributions but also the Chinese Academy of Sciences, the Deutsche Forschungsgemeinschaft, the Max-Planck-Gesellschaft and the Gesellschaft ftir Technische Zusammenarbeit for their financial support. We have to thank all members of the expeditions, including the technical and administration staff, the drivers, Tibetan horse guides etc., for the good co-operation and their help during the various expeditions.

Erosion, debris flows and environment in mountain regions

An International Symposium on Erosion, Debris Flows and Environment in Mountain Regions will be held July 5–9, 1992, in Chengdu, China. The symposium is jointly organized by the International Association of Hydrological Sciences and the Institute of Mountain Disasters and Environment, Chinese Academy of Sciences, in cooperation with the International Union of Forestry Research Organizations and the United Nations Educational, Scientific, and Cultural Organization.

Processes of Occurrence of Mountainous Disaster after War

Processes of Occurrence of Mountainous Disaster after War