摘要
研究目的:金沙江特大桥位于滇西北虎跳峡地区,工程区构造环境十分复杂,断裂构造发育,新构造运动强烈,地震活动频繁,受外围强震带的波及影响较大,遭受历史地震的最大影响烈度达到了Ⅷ度。依托现场调绘、钻探、物探、平硐勘探及室内外试验等获得的新近地质资料,从区域活动性断裂特征、地震活动性、构造稳定性等方面进行分析研究,为桥位的比选提供科学依据。研究结论:(1)近场区呈断块构造格局,挽近时期以来,表现为断块本身的间歇性整体抬升,地应力总体上以水平应力为主;(2)区内活动断裂发育,对桥梁工程影响最大的是中甸-龙蟠-乔后断裂带,全新世以来活动明显;桥址区50年10%超越概率的烈度为7.9度,基岩加速度峰值取226.7g,未来百年内仍有发生多次7级以上地震的可能性;(3)工程区构造稳定性较差,桥位宜差中选优,在场地稳定指数较小的区域通过;(4)本研究成果对构造活跃区桥梁工程的规划选址和工程建设具有指导意义。
Research purposes:Located in the Tiger Leaping Gorge area of northwest Yunnan Province,the Jinsha River Bridge is affected greatly by the outer strong earthquake zone.The structural environment of the project area is very complicated,includes fault structures,strong neotectonic movement and frequent earthquake.In history,the maximum intensity affected by earthquake isⅧ.Based on the data obtained from field survey,drilling,geophysical prospecting,adit exploration and indoor and outdoor experiments recently,this paper has analyzed and studied the characteristics of regional active faults,seismicity and structural stability,which provides a scientific basis for the comparison and selection of bridge positions.Research conclusions:(l)The near-field area presents a tectonic pattern of fault blocks,which is manifested as intermittent overall uplift of fault blocks themselves since the Neoid.In general,the earth stress is mainly horizontal stress.(2)Active faults develop in the region,and the Zhongdian-Longpan-Qiaohou fault which has been active obviously since the Holocene,has the greatest influence on bridge engineering.With 7.9 degrees of the intensity of 50-years 10%overshoot probability and 226.7g of the peak acceleration of bedrock,there is still the possibility of multiple earthquakes of magnitude 7 or above in the next 100 years at the bridge site.(3)With the poor structural stability of the project area,the bridge should pass through the areas with low site stability index by choosing the best from the worst.(4)The research result has guiding significance for the planning site selection and engineering construction of bridge projects in active structural areas.
作者
柴春阳
张广泽
张小林
罗良成
张明
CHAI Chunyang;ZHANG Guangze;ZHANG Xiaolin;LUO Liangcheng;ZHANG Ming(China Railway Eryuan Engineering Group Co.Ltd,Chengdu,Sichuan 610031,China)
出处
《铁道工程学报》
EI
CSCD
北大核心
2023年第10期34-39,44,共7页
Journal of Railway Engineering Society
关键词
地质构造
活动断裂
地震
稳定性分析
geological structure
active fault
earthquake
stability analysis
