GEOLOGICAL HAZARDS AND PROTECTIVE MEASURES OF ROAD SLOPE IN HIMALAYAS MOUNTAIN AREA

The Himalayas is featured by developed tectonic faults, frequent seismic activities, intense neotectonics movement, and abnormal activity of endogenic and exogenic dynamic geological processes. The geological hazards caused by highway construction in plateaus and canyons are extremely developed and poses a great harm to the safe operation of highways in the region. In this study, field investigation and theoretical analysis were carried out to investigate the development pattern of disturbed geological hazards, damage characteristics of protective structures and formation mechanism of road slopes in the Himalayas. According to the slope material composition and stratigraphic structure type, the classification method of highway slope types was put forward and four failure patterns of highway slope were proposed. Spatial statistical method was applied to investigate the characteristics and mechanisms of the geological hazards. It was found that the formation and distribution of road slope hazards in canyons are closely related to regional fault structures, seismic intensity, geotechnical structure types, and climatic and environmental conditions. A few quantitative numerical indicators were further presented to illustrate their relationships. On top of that, the coupling mechanism of endogenic and exogenic geological processes of geological hazards evolution in the Himalayan region was discussed. It is concluded that the relaxation effect of slope rock mass and landslide was induced by the differential uplift and river undercutting and the results of the coupled endogenic and exogenic geological dynamics. On the time scale of road engineering, climate variation is the most active exogenic dynamic geological processes in the region at present. In terms of slope geological hazard protection, there are many uncertainties in the stability of hazard protection projects. In the survey, 10% of the hazard prevention projects showed different degrees of deformation and damage. Through the analysis of the damage characteristics of the protective structure, the reasons for the difference between the protective effect of the protective structure and the stability of the structure itself in the slope disaster protection were clarified. It is suggested that the selection and optimization of the protective structures need to consider the slope engineering geological characteristics, geohazards types, movement paths, failure modes and the engineering compatibility, et al., and adopt multiple protective measures for optimal combination to minimize the occurrence of geohazards and its potential impacts.