我国海上风电场建设的工程地质条件评价

Evaluation of engineering geological condition in the construction of offshore wind farms in China

根据我国近海海域地貌及地层组合,将海上风电场的建设场地划分为3个工程地质区,即基岩覆盖厚(松散层厚度≥100 m)、基岩覆盖中等(松散层厚度为50~100 m)及基岩覆盖薄(松散层厚度≤50 m)的工程地质区。从区域稳定性、场地稳定性及地基稳定性3个方面进行了工程地质条件评价,指出我国海上风电场建设的大部分区段20 m以浅均有可液化砂性土,已构成风电场基础设计中需要防范的主要工程地质问题;在风电场基础设计时,对于基岩覆盖厚及覆盖中等的工程地质区,应选择更新统硬塑状黏性土或中密实的砂砾层为桩基持力层,而基岩覆盖薄的工程地质区可利用中风化岩作为桩基持力层。

According to the geomorphology and formation combination of China’s near-sea area,this paper divided the construction sites of offshore wind farms into 3 engineering geological areas,namely,the engineering geological area with thick bedrock cover(loose bed thickness≥100 m),engineering geological area with medium bedrock cover(loose bed thickness 50 to 100 m)and the engineering geological area with thin bedrock cover(loose bed thickness≤50 m).Considering the regional stability,site stability and foundation stability of the engineering geological evaluation,it is pointed out that most of the construction areas of China’s offshore wind farms(shallower than 20 m)are covered with liquefiable sandy soil,which posed a main engineering geological problem in the basic design of wind farms.Thus,it is necessary to choose Pleistocene hard plastic clay or medium dense gravel layer as the supporting layer of the pile foundation for the engineering geological areas with thick and medium cover of bedrock,while for those of thin bedrock cover,the bedrock-covered engineering geological area can use moderately weathered rock as the supporting layer of the pile foundation.