Research on Parameters Control for Large Shield Tunneling Construction of Submarine Tunnel in Complex Environment
Taking Shantou-Bay Submarine Tunnel of the newly built Shantou to Shanwei Railway as the research object,this paper analyzes the variation patterns of shield tunneling parameters in complex environments such as upper-soft and lower-hard strata,and full section hard rock,and proposes corresponding excavation control measures.The results show that the shield tunneling time cost,average tunneling speed,average torque,and cutterhead extrusion pressure can accurately reflect the geological properties of the upper-soft and lower-hard strata on the tunnel face,while the total thrust force value and rotational speed of cutterhead are not sensitive to geological changes in the upper-soft and lower-hard strata.The tunneling speed should be controlled at around 5 mm/min,the rotational speed of cutterhead should be 0.8 to 0.9 r/min,and the total thrust force value should be controlled at 95000 to 110000 kN,the torque of the cutterhead should be controlled between 3 to 6 MN·m,and the cutterhead extrusion pressure should be controlled around 25000 kN.Pre-blasting can be used to reduce the integrity and mechanical strength of the rock for sections with large rock surface fluctuations and hard rock.In the hard rock section,for every increase of 1000 kN in the cutterhead extrusion pressure,the force on a single cutter increases by about 1.2 t,and the torque of the cutterhead changes slightly,the tunneling speed increases by about 15 mm/h,and the total force on the cutting tool is controlled at around 85%to 90%.Construction control measures such as replacing new roller cutters,reducing the spacing between cutters,and reducing the width of the cutting edge have been proposed to achieve rapid and safe construction of the shield tunnel.
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