渤海海峡跨海通道围岩条件探查与施工方法分析

渤海海峡跨海通道是连接中国山东半岛与辽东半岛重要的交通运输干线工程,该通道的建成对于推动环渤海地区经济的快速发展及振兴东北老工业基地具有重要意义。而通道区域的围岩条件及岩石的力学性质对于该工程施工方案的优选十分重要。通过区域地质调查、海域地层钻探和地层剖面实测以及岩石力学性质分析表明:通道区域内出露的地层从上到下依次为第四系、新近系与上元古界;其中第四系厚10~120 m,主要是一些松散的沉积物,没有隔水层,稳定性差;新近系不发育,仅在局部地区零星分布,主要由大孔隙的玄武岩构成,其抗压强度等岩石力学性质指标偏低,且低于正常值;而上元古界则由石英岩与石英岩互层的板岩和千枚岩构成,石英岩稳定、坚硬,抗压强度和抗剪强度大,板岩和千枚岩属于软质岩石,遇水易软化。因此,在已有的"全隧道"和"南桥北隧"两种方案基础上,建议渤海海峡跨海通道"北隧"段采用深埋隧道法,即该隧道不仅应穿越上部的第四系和新近系,还要穿越上元古界与石英岩互层的的板岩和千枚岩,而设置于石英岩中。根据通常采用的利用围岩确定隧道最小埋深的挪威法,建议北段隧道的最小埋深应在65 m左右。另外,由于石英岩比较坚硬,因此,渤海海峡跨海通道工程宜采用钻爆法和TBM法进行施工。 

THE SURROUNDING ROCK CONDITION EXPLORATION AND CONSTRUCTION METHOD ANALYSIS OF CROSS-BOHAI STRAIT PASSAGE

The cross-Bohai Strait passage is not only an important traffic and transportation project which connects Shandong Peninsula and Northeast regions, but it is also of vital significance for promoting the economic development of the Bohai-ring and revitalizing the northeast old industrial base. For the determination of the construction scheme of the project, it is necessary to analyze the surrounding rock conditions and the mechanical properties of the rocks. According to the regional geological survey, formation drilling in the sea area, stratum profile measurement of Bohai Strait and analysis of rock mechanics properties, it is shown that the exposed strata in the passage area are Quaternary, Neogene and Upper Proterozoic from top to bottom, respectively. The Quaternary strata is 10~120 m thick, which are mainly loose sediments, with no impermeable layers and poor stability. The Neogene rocks are scarcely found and scatter only in some areas. They mainly consist of macroporous basalts, and the mechanical properties index of basalts such as compressive strength is relatively low, even lower than normal values. The Upper Proterozoic is composed of quartzite and quartzite interbedded slate and phyllite. Quartzite is stable and hard, having a high compressive strength and shear strength, but slate and phyllite are soft rocks, which are easy to soften when exposed to water. Therefore, based on the two plans of "the whole tunnel" and "bridge in the South and tunnel in the North", it is suggested that the deep-buried tunnel method should be used in the "North Tunnel" section of cross-Bohai Strait passage, which means the tunnel should be located in the Upper Proterozoic quartzite under the Quaternary and Neogene strata. By the method for determining minimum buried of tunnel, the minimum depth of tunnel should be about 65m. In addition, due to the hardness of quartzite, the drilling-blasting method and TBM method should be adopted for the construction of cross-Bohai Strait passage.