Geohazard development rules and post disaster reconstruction strategies of Hailuogou scenic road in the epicenter of Luding earthquake
The"9·5"Luding earthquake triggered a large-scale co-seismic geo-hazard in the Hailuogou scenic area.Half of the scenic road sections were located within the range of seismic intensity IX(9 degrees),resulting in severe damage to the roads and the complete loss of traffic capacity.To explore the geo-hazards development rules and post disaster reconstruction strategies of Hailuogou scenic road,multi-dimensional and stereoscopic methods were comprehensively employed,including remote sensing,LiDAR,unmanned aerial vehicle oblique photography,field survey,geological exploration,and the automatic extraction of structural planes.These approaches enabled a systematic investigation of the geo-hazards in the study area from the regional level to the local site.The results showed that:(1)there were 503 co-seismic geo-hazards developed in the study area,with a total area of 3.75 X 106 m2.These geo-hazards were primarily concentrated along the right side of section K10-K15,within an elevation range of 1 900 m to 2 900 m and a slope range of 30° to 60°.(2)The distribution rules of geo-hazards were mainly controlled by factors such as topography,lithology,epicenter,and river,and the spatial coupling with the main fault was not particularly strong.(3)The instability modes of geo-hazards could be divided into three types:high-level collapse,deposit landslide,and shallow slope surface collapse,which exhibited the characteristics of large quantity,linear distribution,and different scales.Among these,high-level collapse was mainly observed in hard rock areas such as granite and dolomite,while landslides and shallow collapses mainly appeared in soft rock areas such as schist and slate,and on the ice water accumulation slope of the Moxi Platform.(4)The deep canyon terrain and high seismic peak acceleration caused seismic amplification effects in the rupture zone of the hard rock slope,resulting in a large scale of high-level collapse.A hysteresis phenomenon was observed in the overall instability of thick deposit landslides under strong earthquake action.(5)In accordance with the geo-hazards development rules,the post disaster reconstruction project of roads in Hailuogou scenic area adopted the concept of disaster reduction and route selection,and adhered to the principle of avoiding major geo-hazard and treating minor geo-hazard.Four tunnels were constructed to avoid high-position collapses,and thirteen bridges were built to cross potential debris flow gullies.In conjunction with in-situ treatment measures such as grouting steel flower pipes and anchor rod frame beams,the disaster prevention and resistance ability of scenic roads was enhanced.The results systematically revealed the geo-hazards development rules of the Luding earthquake epicenter area.The proposed post disaster reconstruction strategies were comprehensively applied in engineering practice,providing important support for disaster identification and evaluation and post disaster road reconstruction work in strong earthquake areas.
engineering geologyLuding earthquakeHailuogou scenic roadhigh position collapsegeo-hazard characteristicsdevelopment rulesreconstruction strategies
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