Sponsor(s): China Railway Tunnel Consultants Co.,Ltd.
12 issues per year
Current Issue: Issue 11, 2018
Tunnel Construction was hosted by China Railway Tunnel Consultants Co.,Ltd. It mainly publishes research results and advanced technologies in tunnels and underground engineering and related fields; the content of the publication is based on practical technology, taking into account experiments, research and comprehensive reviews, designing tunnels and underground works in railways and highways, and related institutional projects, Water conservancy projects, geotechnical engineering, engineering blasting, engineering materials, engineering machinery, engineering management and other majors. Domestic and international scientific and technological information and industry trends in related fields.
Tunnel Construction,2018,Vol 38,No. 11
The author discusses the necessity and urgency of constructing the Bohai Bay Crossing Corridor from the following aspects such as the increasing traffic volume, the convenience of the transportation after the corridor is constructed, and the regional benefit brought by the corridor. As for the timing of the construction of the sea-crossing corridor, the author thinks that as long as the national economic situation permits and relevant conditions are basically available, the preliminary work should be carried out as soon as possible so as to promote the early commencement of the construction. Regarding the proposal of building another coastal national highway/high-speed railway along the Bohai Bay coast, the author puts forward his viewpoints. In the aspect of construction risks, the author thinks that the geological risks in the construction of the Bohai Bay Crossing Corridor are very difficult to be dealt with; therefore, strict and detailed risk assessment should be carried out, and effective safety measures should be taken to mitigate the risks. The author also briefly describes the technological advantages of the tunnel proposal selected for the Bohai Bay Crossing Corridor, and briefly analyzes some key technological issues in the tunnel construction. The author describes the construction scheme and construction period estimation for the sea-crossing corridor in details. The author makes the following proposal are given: (1) the hard rock tunnel boring machine (TBM) assisted by the drilling and blasting method should be used for the construction of the long sea-crossing tunnel of Bohai Bay Crossing Corridor; (2) a parallel service tunnel shall be arranged between the twin main tunnel tubes; (3) in Proposal 2, the diameters of the twin main tunnel tubes and the service tunnel should be φ8.0 m and φ5.5 m, respectively. The proposal has two optional solutions: Solution 1: The service tunnel ( φ5.5 m) located between the main tunnel tubes will be constructed first; for the main tunnel tubes, the disassembled TBMs ( φ8 m) and the backup gantries are assembled for tunneling after arriving at the main tunnel tubes through the service tunnel and the cross passage; Solution 2 (alternative): Tunneling with φ5.5 m TBM is carried out; the φ5.5 m TBM will be dismantled to pass through the cross passage, and then be re-assembled after arriving at the main tunnel; the start section (180 m) of main tunnel tube will be formed by φ5.5 m TBM before it is enlarged to φ8 m by drilling and blasting method; or the cross passage is enlarged to a large curved space to allow the φ5.5 m TBM passing throught without disassembly. Comparison and contrast will be made and the preferred solution will be adopted. According to the rough estimation on the construction period of the 125 km long sea-crossing tunnel, the total construction period of “completed tunnel” will be about 19 years (including 5 years of detailed offshore investigation) in Solution 1.
Application Technology of Spray-applied Waterproofing in Unloading Tunnel of an LNG Receiving Terminal
Tunnel Construction,2018,Vol 38,No. 11
The application of a spray-applied waterproof membrane in the case of the liquefied natural gas (LNG) unloading line tunnel constructed via the New Austrian Tunneling Method (NATM) is described. The waterproof standards for the LNG unloading line tunnel are stricter than those for regular tunnels based on the consideration of safety and environmental protection during operation. A double-layer waterproofing system including radial grouting, systematic drainage facilities, an EVA sheet membrane, a spray-applied acrylate waterproof membrane and other waterproofing and drainage facilities are designed based upon comparisons among several possible waterproofing solutions. The application results and consequential observations prove that the outcome of this waterproof system is satisfactory. The important issues for the successful application of the sprayed membrane in this case are summarized, including a reasonable design for the waterproofing system, performance of the sprayed membrane, proper training for the operators, adequate preparations, careful execution, and complete quality control and acceptance. The successful application of the spray applied acrylate waterproof membrane combined with other waterproofing and drainage facilities in this case has been demonstrated according to the inspection results and provides alternative solutions to improve the waterproof quality of similar tunnels under high standards.