Abstract:

The author discusses the engineering feasibility of the construction of Taiwan Strait Tunnel and provides his viewpoints and suggestions for some key technical issues of the project in the following 10 aspects. 1) The engineering feasibility of the design and construction of the subsea tunnel in view of the geologic and seismic hazardous conditions of the proposed location of Taiwan Strait Tunnel: taking "North Line Plan" as an example to discuss their impact on the construction and operation of the tunnel; 2) The characteristics and problems of the design and construction of the subsea tunnel: comments and suggestions on the geologic investigation, the minimum cover depth of the tunnel, transportation tools in the tunnel, setting of service tunnel and subsea crossover chamber and safety design and safe construction of the project; 3) Prediction and prevention of hydrologic regime and water gushing hazards in the tunnel sections with unfavorable geology: understanding and value of the hydrologic conditions in the tunneling site; discussions on basic rules for cavein prevention and water gushing prevention and unpredictable construction risks and key points of construction countermeasures; 4) Earlywarning, deformation prediction and control of the cavein of the tunnel surrounding rocks: evaluation on the stability of the surrounding rocks  by "Deformation Rate Ratio System Method", and adjustment  and correction of the original design parameters of the tunnel lining by BMP Software during the construction; 5) Comparison between Tunnel Boring Machine (TBM) method and drilling and blasting method based construction schememodernization of tunnel construction machinery: proposing a composite construction scheme combining TBM and drilling and blasting method for the tunnel and suggesting the modernization of the major tunnel construction machinery and monitoring apparatus (such as automatic shotcrete robot and automatic measuring and monitoring and feedback system) when drilling and blasting method is applied in part of the tunnel sections; 6) Corrosionproof highperformance oceaneering concrete material and tunnel lining structure: providing basic approaches to produce highperformance oceaneering concrete with conventional materials so as to improve the durability and providing suggestions for the design and construction of excavation, support, construction water drainage and pressure limiting lining of tunnel sections in rock masses with unfavorable geology; 7) Ventilation of superlong and big tunnel during operating: being considered as a railway tunnel and taking Channel Tunnel as an example to explain the aerodynamics of Taiwan Strait Tunnel and presenting the principle and structure layout of the ventilation system of Channel Tunnel; 8) Tunnel disaster prevention and mitigation: suggesting learning and referring to the tunnel disaster prevention design concept in Japan and some western countries; 9) Risk assessment and management for the construction of the subsea tunnel: providing the types of the major technical risks of this tunnel and providing the author′s understanding on risk management; 10) About the submerged floating tunnel: suggesting further and cautious considerations on the plan of submerged floating tunnel based on the conditions of this tunnel; and finally identifying the geologic and seismic investigations to be deeply furthered in the next step.

Key words: Taiwan Strait Tunnelsubsea tunnelengineering feasibilitykey technical issue, designconstruction, cavein preventionwater gushing hazardTunnel Boring Machine (TBM)drilling and blasting methodventilationdisaster preventionrisk