| As a long-standing technical problem in the field of highway safety,it is difficult to evaluate the safety risk of highway slope in mountain area comprehensively and effectively by existing technical methods.At the same time,the situation of disaster prevention and control of highway slope in mountain area is becoming more and more serious.The frequent occurrence of geological disasters such as landslides,collapses and debris flows has posed a great threat to mass safety and highway construction.Slope safety is directly related to the long-term stable operation of highways and the safety of people's lives and property.Therefore,it is necessary to introduce more new technologies and methods into the safety risk assessment of highway slopes in mountainous areas and establish a systematic and complete evaluation system in order to obtain more comprehensive and accurate results of slope safety risk assessment.Therefore,it can provide effective decision support for the prevention and mitigation of highway slope disaster,and minimize the risk of slope geological hazards and the possible damage losses caused by the hazards.In view of the above problems,this paper combines the advanced knowledge system of surveying and mapping engineering,highway engineering,slope engineering and safety engineering and other interdisciplinary disciplines,with reference to the relevant regulations and standards of surveying and mapping industry,ministry of communications and emergency management department.Supported by threedimensional laser scanning technology,steep slope point cloud filtering algorithm based on laser echo principle and Fisher decision rule,improved ICP uncontrolled matching algorithm based on IGG robust estimation theory and grid nearest neighbor query,NURBS high-precision surface model reconstruction technology,improved entropy weight set pair analysis model and AHP-fuzzy comprehensive evaluation method,etc.Based on risk macro-evaluation index system of highway slope in mountainous areas and the vulnerability evaluation index system of highway disaster in mountainous areas,Taking risk macro-evaluation of highway slope in mountainous area,risk microassessment of highway slope in mountainous area and vulnerability assessment of highway disaster in mountainous area as the framework,A systematic,comprehensive and multi-method combined application of highway slope safety risk assessment system in mountainous areas is established.The main achievements and innovations of this paper are as follows:(1)A risk assessment model of highway slope based on entropy weight set pair analysis and three-dimensional laser scanning technology is constructed.This model combines macro and micro risk assessment.Firstly,the improved entropy weight set pair analysis model is used to evaluate the overall macro-level of the highway slope,and then the three-dimensional laser scanning technology is used to conduct in-depth micro-level evaluation.The model can first determine the overall dangerous grade of each slope in the study area by macro-evaluation method(entropy set pair analysis),and find out the dangerous slope.Then,the specific dangerous areas(hidden danger points)in dangerous slopes are identified by micro-evaluation method(deformation and displacement analysis of slopes based on laser scanning).Thus,the three-dimensional risk assessment of highway slopes in mountainous areas can be realized from macro to micro,from whole to local,and from surface to point,so as to obtain more complete and comprehensive assessment results.At the same time,it also provides a new idea for the study of highway slope risk assessment.(2)A risk macro-risk evaluation index system of highway slope in mountainous areas is constructed,which consists of 14 core indicators of four major factors,including slope topography,rock and soil geology,meteorology and hydrology,and other factors.Based on the principle of extensibility of connection degree,set pair analysis theory is optimized and improved,and an improved model of set pair analysis based on entropy weight method is constructed.The results show that the evaluation results of the improved entropy weight set pair analysis model are basically consistent with those of other traditional evaluation methods,reflecting good accuracy.It shows that it is feasible to apply the model to the risk macro-evaluation of slope.At the same time,it also provides a new method for the study of the risk macro-evaluation of highway slope.(3)The accuracy of slope deformation analysis(risk micro-evaluation)results is directly related to the quality of slope point cloud treatment.Therefore,this paper makes a thorough exploration and research on the relevant algorithms of slope point cloud treatment.A steep slope point cloud filtering algorithm based on laser echo principle and Fisher's decision rule is constructed.A steep slope Point Cloud Filtering Algorithm Based on the principle of laser echo and Fisher's decision rule is constructed.The algorithm first uses the principle of laser echo to roughly classify the point cloud data,and then uses Fisher's decision rule to fine classify the remaining point cloud after roughly classifying.The results show that,compared with other filtering algorithms,the total error rate of the proposed algorithm is the smallest,reflecting a good filtering accuracy.An improved ICP uncontrolled matching algorithm based on IGG robust estimation and grid nearest neighbor query is constructed.This algorithm not only utilizes IGG robust estimation theory to enhance the robustness of ICP algorithm,but also improves the operational efficiency of ICP algorithm through the idea of grid nearest neighbor query.The results show that compared with the traditional ICP algorithm,the improved ICP algorithm in this paper has faster computation speed and stronger robustness,thus effectively improving the point cloud matching efficiency and accuracy.NURBS modeling technology is introduced into the construction of high-precision model of highway slope in mountainous areas.The results show that the NURBS surface model is more complete and accurate than the triangular surface model and DEM model in expressing the surface details of highway slopes in mountainous areas,and has better fitting degree for complex terrain slopes,and its model effect is more suitable for the real undulating state of highway slopes in mountainous areas.(4)An evaluation index system of highway disaster vulnerability in mountainous areas is constructed,which consists of 8 core indicators of social economy,road engineering and highway protection.The quantitative and qualitative comprehensive evaluation of vulnerability of highway disasters in mountainous areas is realized by using AHP-fuzzy comprehensive evaluation method.The results show that the evaluation results of AHP-fuzzy comprehensive evaluation method are basically consistent with the qualitative analysis results of experts,reflecting good accuracy and applicability.It shows that it is reasonable and feasible to use this method to evaluate the vulnerability of highway disasters in mountainous areas.At the same time,it also provides a new reference for the research on the vulnerability evaluation of highway disasters in mountainous areas.(5)Based on the safety risk assessment system of highway slope in mountainous area,the application experiment of a highway slope in Taihang mountain area of Xiuwu County was carried out.The experimental results are as follows: Firstly,the results of risk macro-assessment of slope show that the risk of No.2 and No.3 slopes in the study area is relatively small,while that of No.1,No.4 and No.5 slopes is relatively high.Secondly,the specific dangerous areas of No.1,No.4 and No.5 dangerous slopes are identified by risk micro-evaluation.Then,through the evaluation results of highway disaster vulnerability,it can be seen that the vulnerability of highway disaster in the study area is grade IV(extremely high).Finally,for the dangerous slope,the corresponding disaster prevention and control suggestions are put forward. |
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