Study On Water-related Disaster Damage Assessment And Mitigation Method Of Mountainous Highway Along River

In the current climate changing and disaster frequently happening background, as the most widely distributed and most convenient transportation infrastructure, highway is often affected by adverse action effect of disasters, at the same time highway also provides traffic support for emergency rescue and disaster relief, therefore the study of water-related highway disaster risk assessment in mountain area for highway along the river has important significance. Risk assessment is an important aspect of the discipline for disaster prevention and mitigation science, it can provide decision support to mountain area highway geological safety. This paper takes the water-related highway disaster risk of highway along river in mountain area as the research object, performs the study of formation mechanism, risk evaluation and disaster reduction method for water-related highway disaster of mountainous riverbank highway through a lot of field survey and by combining the theories and comprehensive research methods of disaster science, water-related highway disaster science, disaster geology, geomorphology, rock-soil mechanics, hydraulics, GIS technique, numerical simulation, etc., the main achievements are obtained as follows:1) Based on the mountainous riverbank highway construction and maintenance demand, set up the water-related highway disaster theory and mitigation technology framework from the aspects of water-related highway disaster classification, risk formation mechanism, risk evaluation and relief measures etc. Puts forward the concepts of highway geology safety and water-related highway disaster risk evaluation for mountainous riverbank highway, enriched the scientific connotation of highway maintenance. Paying attention to disaster effect caused by flash floods of small watershed and river flood along river, this paper put forward the concept of water-related highway disaster body.2) Based on the highway damaging mechanical model under the action of water-related highway disaster body, classified the water-related highway disaster into five major types, that is pushing, pulling,"impacting","silting" and "seepage", the new classfication of water-related highway disaster can facilitate the mechanical mechanism research of water-related highway disaster damage to riverbank highway in mountainous area. Damage mechanism of highway were studied through the finite element numerical simulation of typical highway water-related disaster, and the numerical simulation research mainly focused on the landslide pushing, landslide pulling, rockfall shock, erosion groove expansion, debris flow burying and culvert seepage action to highway, obtained the deformation and failure law of highway caused by typical water-related highway disasters.3) Put forward the coupling and confrontation mechanism of water-related highway disaster risk, that is water-related highway disaster risk is the result of coupling and confrontation between hazard of water-related highway disaster body and vulnerability of highway hazard-bearing body. Thought water-related highway disaster risk assessment is about the prediction and evaluation study on the multi-factors and nonlinear disaster risk system. According to the coupling formation mechanism of water-related highway disaster risk, put forward the decoupling disaster alleviation idea to reverse control the formation processes of water-related highway disaster risk.4) Put forward the catastrophe-coupling development mechanism of water-related highway disaster body by interaction between disaster-breeding environment and disaster-causing factor. Based on the health concept of highway hazard-affected body, thought hazard-bearing body vulnerability is mainly controlled by the health state of highway structure, the purpose of engineering disaster alleviation measures is making structure health recovery by taking technically feasible and economy reasonable measures. Classified the highway hazard-affected body into two types, that is structural and functional ones. In regard to mountainous riverside highway, given the work ideas and general function expressions for assessment of disaster-breeding environment, disaster-causing factor, water-related highway disaster body hazard, hazard-bearing body vulnerability and water-related highway disaster risk.5) Established the flash flood hazard evaluation method for highway at the outlet of small watershed. Based on morphometric analysis of watershed, extracted the quantitative parameters of watershed geomorphology such as bifurcation ratio, river frequency, RHO ratio and shape factor etc. Comprehensively considering the relationship between the quantitative parameters of geomorphology and flash flood hazard for sub-basins, the hazard degree of outlet sections of highway for the sub-basins was quantified and classified.6) Constructed collapse and landslide hazard evaluation method and index weight calculation method of mountainous highway along river. Based on the catastrophe-coupling development mechanism of collapse and landslide by interaction between disaster-breeding environment and disaster-causing factor, using geographical information system and remote sensing technology means, collapse and landslide hazard evaluation method was constructed on the basis of factor analysis, index selection, basic database established, the calculation of information index and index weight of collapse and landslide. Based on the historical avalanche and landslide disaster area distribution information entropy, established the evaluation index weight calculation method for mountainous collapse and landslide hazard evaluation of riverbank highway, and the weights obtained from this method is objective to some extent.7) Established hazard assessment method of debris flow along highway based on geomorphic evolution stages. Highway debris flow hazard can be assessed based on the established relationships between evolution stage of debris flow gully and disaster scale, frequency and hazard level. Research shows that in strong-to-young stage the debris flow gully has the highest hazard level, and the rank of hazard level in life cycle of debris flow gully from high to low is strong-to-young, strong, young, strong-to-old, old.8) Hazard evaluation of flash flood, debris flow, collapse and landslide was performed for riverside highway in Meigu river of Hengduan Mountains, verified the validity of hazard evaluation method established in this paper, and drew some useful conclusions about water-related highway disaster risk, which could provide supporting for highway disaster prevention and mitigation decision-making of local highway maintenance department.9) Flood damage process and mechanism of mountain area riverside subgrade including washout and collapse gap were studied from the perspective of fluid-structure coupling dynamics, turbulent mechanics and mechanics of sediment movement. Based on the mechanism research of flood-induced highway damage, selected vulnerability evaluation index of hazard-affected body, quantified and classified the indexes, performed the vulnerability evaluation for main hazard-affected bodies of highway along river in mountainous area.10) Based on evaluation unit alignment of water-related highway disaster risk, hazard degree calculation method under multi-disasters was established for mountainous highway along river. And integrated vulnerability degree and potential highway disaster loss estimation methods were given respectively. Implicit calculation expression for water-related highway disaster risk was established by coupling hazard degree, vulnerability degree and potential highway disaster loss together, and explicit calculation model for water-related highway disaster risk was discussed.11) Disaster relief frame system for highway along river in mountainous area was put forward by emphasizing the importance of nonstructural disaster mitigation measures such as water-related highway disaster risk assessment, the present research situation and further research direction of water-related highway disaster control measures were summarized systematically from structural and nonstructural countermeasures. The nonstructural water-related highway disaster countermeasure of highway along river in mountainous area was discussed from maintenance innovation consciousness to disaster early warning based on risk assessment. According to the action characteristics of flood and debris flow performed on highway structure along river, expanded the structural disaster reduce measure by curved surface roadbed protection structure for subgrade along mountainous riverbank.