the world's longest undersea high-speed railway tunnel overcomes the first section of hard rock formation
2024-09-16
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china news service, ningbo, september 14 (zhang bin and ma jingbo) on september 14, the first section of the full-section dacite stratum excavation was completed on the ningbo side of the jintang undersea tunnel of the yongzhou railway, marking a phased victory in the construction of the world's longest undersea high-speed railway tunnel.
the ningbo-zhoushan railway starts from yinzhou district of ningbo city in the west and ends at dinghai district of zhoushan city in the east. it is about 77 kilometers long with a designed speed of 250 kilometers per hour. after it is opened to traffic, it will take only 30 minutes to travel from ningbo to zhoushan by rail, ending zhoushan's history of not having a railway.
the jintang undersea tunnel is 16.18 kilometers long and is excavated from ningbo and zhoushan by two shield machines. the "yongzhou" shield machine with a diameter of 14.57 meters is responsible for the excavation of 4,940 meters on the ningbo side.
"the geological conditions on the ningbo side are complex. the tunnel will first pass through the city and then the sea. it will pass under more than 40 risk sources such as oil pipelines, seawalls, docks, and port access channels." hu hao, project manager of the ningbo-zhoushan railway of china railway 14th bureau, introduced that hard rock and uneven hard and soft strata account for nearly 70% of the construction area of the "yongzhou" shield machine. it is necessary to complete the excavation of 12 sections of hard rock strata and undergo 24 changes in soft and hard strata. the strata and sea environment are extremely complex.
at present, the shield machine has entered the upper soft and lower hard strata for excavation, which is a more complex composite stratum.
"this stratum is like a complex 'geological sandwich'. the soft soil on the upper layer is like a soft layer of bread, with low strength and poor stability, while the hard rock on the lower layer is like hard slices of ham, with high hardness and strength." said dong bing, chief mechanic of the ningbo-zhoushan railway project of china railway 14th bureau.
therefore, the conquest of the first section of hard rock strata has accumulated more experience for the subsequent undersea tunnel excavation. (end)
(source: china news network)
