| Baofu Expressway is an important part of the highway network of Beijing-Tianjin-Hebei and Hebei province.It is an important traffic corridor connecting the central area of Hebei province and Shanxi province.It will play an important role in improving the Hebei highway network,accelerating the integration of Beijing-Tianjin-Hebei region,and promoting regional economic development.However,the geological environment of the crossing area is complex and diverse,which makes the highway have great uncertainty during the later operation period and faces the potential threat of various types of geological disasters.Once the geological disaster occurs,it will cause serious damage to the lives and property of the people and the social impact is enormous.This paper takes the Baofu Expressway as the research area.Based on the extensive collection of previous research results and combined with the field survey data of geological disasters,the developmental characteristics,space-time distribution and influencing factors of geological hazards in the research area are investigated,and the evaluation index system was established.Finally,the risk assessment of the geological hazard along the Baofu Expressway was completed and the main research works of this paper are as follows:(1)Based on the extensive collection of geological data such as topography,stratigraphic lithology and regional geological structure background along the Baofu Expressway and combined with the field survey data of geological disasters,the development types and space-time distribution of geological hazards are summarized and analyzed.The background conditions and mechanism of geological disasters along the Baofu Expressway were preliminarily revealed.(2)The risk assessment factors of geological hazards were determined through correlation statistical analysis.According to the development characteristics of geological disasters along the highway and the dynamic geological conditions inside and outside the study area,10 factors,such as slope,topographic undulation(Height difference),slope direction,engineering geological group,fault,river system,vegetation coverage,rainfall,peak acceleration of ground motion,human engineering activities,are selected and the risk assessment index system of geological hazard was established.(3)Based on the analytic hierarchy process and the coefficient of variation method,and combined with the principle of relative entropy,a combined weighting model was established to carry out the risk zoning of the geological disasters along the Baofu Expressway and the results were verified.The results are consistent with the distribution of existing geological disasters.Among them,the low-risk area is about 792.02km~2,the medium-risk area is 1126.34km~2,the high-risk area is 764.07km~2,and the extremely high-risk area is 297.15km~2,accounting for 26.58%,37.80%,25.64%,and 9.98%respectively.(4)The mineral composition analysis of typical landslides in the study area was carried out by XRD powder diffraction experiment.There are significant differences in clay content at different locations of the landslide.The clay minerals content of the slip zone is much higher than that of the sliding bed and the sliding body,and the dominant expansive clay minerals is important for the formation of the slip zone.Clay minerals and landslides are not simple one-way effects,but rather a mutual-driven and mutual-feed relationship.In general,the content and distribution of clay minerals in the slopes are key factors controlling the development of landslides in the study area.(5)The formation mechanism,movement mechanism and accumulation of debris flow in yuanjiahui are studied.On the basis of field investigation and extensive collection of predecessor data,FLO-2D software was used to simulate the debris flow ditch that exists engineering conditions under the 10,20,50 and 100 year rainfall conditions,and the starting,evolution process and accumulation of debris flow were obtained respectively. |
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