Regional Crustal Stability Assessment Of Bailongjiang Water Diversion Project

Bailongjiang water diversion project from southwest to northeast mainly includes Longnan,Longzhong and Longdong areas.The route area has complex structure,frequent earthquakes,frequent strong earthquakes and geological disasters,and obvious engineering geological problems.However,there is no special study on the regional crustal stability.Starting from two aspects of structural stability evaluation and surface stability evaluation,this paper systematically studied the engineering geological conditions of Bailongjiang diversion project approach area,sorted out the main factors affecting crustal stability,and quantitatively evaluated the crustal stability of Bailongjiang diversion project area by using the method of fuzzy mathematics evaluation.Structural stability evaluation is the main aspect of regional crustal stability evaluation,and fault zone activity and seismic risk are the two most important indicators affecting structural stability analysis and evaluation.Through statistical analysis of distribution and characteristics of fault zones in the study area,it is concluded that strong active faults account for 23.8%,strong active faults account for33.3%,medium active faults account for 28.6%,weak active faults account for 14.3%,and strong active faults account for the predominance.Through the statistical analysis of geological hazards in the study area and in other areas,the results show that geological hazards occur frequently in the study area,and their manifestations are different.In the central and southern regions,landslides and landslides are dominant,and debris flows are mostly associated.They are viscous debris flow areas represented by Longnan and loess debris flow areas represented by Longxi,Tianshui and Qingyang.The dominant distribution direction of geological hazards in the study area coincides with the NEE-trending fault line,and shows a significant decreasing trend in the South and North directions.The results of structural stability evaluation show that the unstable area accounts for 38.9%,the sub-unstable area 27.4%,the sub-stable area 16.6% and the stable area17.1%.The surface stability evaluation results show that the unstable area accounts for 59.6%,the sub-unstable area 11.0%,the sub-stable area 12.3%,and the stable area17.1%.In general,the evaluation results of crustal stability in Bailongjiang diversion project area are as follows: the unstable area accounts for 66.3%.The sub-instability area accounts for 12.1%,the sub-stability area 4.5% and the stability area 17.1%.Overall,the evaluation results show that the crustal instability is dominant in the diversion area,and the tectonic stability is dominant.The surface stability is consistent with the tectonic stability.Through the statistical analysis of historical earthquakes and strong earthquakes in the study area,and comparing the results of regional stability evaluation with the seismic risk zoning map of Gansu Province,it is found that most of the unstable areas and relatively unstable areas in the evaluation map coincide with the prediction range of seismic risk zoning,indicating that strong earthquake activity is an important factor affecting the regional crustal stability of the study area,and most of the seismic risk zones are unstable Fixed area.