The shield tunnels of Construction Contract CB420 of Taipei Metro were driven underneath the runway and one of the taxiways of the Taipei Songshan Airport and it was very necessary to reduce potential risks during tunneling so flights would not be interrupted. The Contractor adopted several measures to minimize ground settlements and closely monitored the ground response to tunneling. A vast quantity of data of high quality were obtained for studying the effectiveness of the measures adopted. The Department of Rapid Transit Systems engaged a team of experts to form an Ad Hoc Committee to review the Contractor’s construction plan and the data collected during tunneling. The ground conditions at this site are uniform in comparison with others and the site if free of underground utilities and traffic. This provides an ideal opportunity for studying the ground response to tunneling. It has been found quantitatively that ground settlements are closely related to the imbalance of the materials taken out of the tunnel and the materials put into the tunnel.
This paper gives a successful case study of shield tunnel, CO3 section Orange line of KRTC, passing through National freeway No. 1. The going and coming shield tunnels, buried at 13~19m beneath ground, are 50m long in each and are around 10m apart from bridge abutment. This paper presents the settlement analysis and monitoring results of the MRT crossing freeway. It is expected that the concepts and suggestions described in this paper would be helpful for the similar engineering cases in the future.
Shield tunnel is the most popular construction method in Taipei metropolitan area rapid transit systems at this art. The characteristics of MRT are not only safe, economic and speedy but also keeping traffic smoother. However, nowadays, cause of highly-developed urban, the depth of working shaft for shield-tunneling is getting deeper and deeper. Except for traditional ground grouting method, it is necessary to apply the ground freezing method for assisting to prevent the underground water flow and achieve the “Reinforced Defense” goal. Ground freezing method is the most safety method on water stopping, but it will cause large-scale accident in lacking of risk management. The paper will introduce & discuss the procedure of risk management on ground freezing method of Taipei MRT CK570C Lot construction project.
This document provides information on the working method for the Double O-Tube (DOT) bored tunnel, used for the first time, for the Sanchong to Taipei Main Station section of the Taiwan Taoyuan International Airport Access MRT System Construction Project. It introduces the process and method of analysis, as well as the parameters used, for the DOT bored tunnel design. As the shape of the lining segments of DOT bored tunnels differ from that of original circular segments, special segments are used – including the so-called ‘seagull segment’, as well as a center column segment separating the tunnels’ up and down tracks. Each of these three types of lining segments has different design considerations. The special characteristic of the DOT bored tunnel is the use of the beam-spring model for the method of analysis. Besides setting curve beams for linings and soil springs, the rotational springs and shear springs are used for simulating segment connections to represent staggered effect. Thus the tunnel is optimally designed. Nonetheless, the new method inevitably calls upon the need for mitigation of difficulties arising from the actions of people and the environment. This document is only a summary, but it is hoped that new doors will thus be opened for the next milestone in Taiwan’s tunneling methods.
Taiwan Taoyuan International Airport Access MRT System is the main line of the transportation from national key portal of Taoyuan Airport to urban areas. The construction of the route, including elevated guideway passing by densely-populated urban district through Taiwan National Highway No. 1 and underground sections underpassing the distinctive sections of Tamsui Riverbed and airport taxiway and control tower area, is huge and complicated; and the construction risks of each section is considerably high. In addition to the method of perfect construction management, the Project is generally controlled by the construction risk management strategies to carry out design concept of〝the continuity to implement construction risk management〞, to implement 〝the control system of high-risk work items during construction stage〞 to build up 〝the database and information platform of risk management〞, and to reinforce〝the crisis handling capability〞 to meet the effective risk management of project construction. The text provides the experiences with actual cases in overall construction management, and it is expected to be paid more attention by engineering societies and to incorporate risk management into construction management system so as to ensure project construction safety.
The route of Taiwan Taoyuan International Airport Access MRT Construction Project at the Taiwan Taoyuan International Airport section is mainly pass through with shield tunnel, and the mainly strata of this section is gravel formation. This paper describes the design consideration and treatment of shield machine in gravel layer, and the problems and solutions during construction.
This paper presents the case study of underground retaining structure, including design and construction process for diaphragm wall and full-cased piles iin gravel ground condition. due to different size and hardness, it is difficult to use the traditional investigation technique to obtain undisturbed sample in gravel layer for laboratory experiment. in-situ experiments and large scale cased pile tests were used to obtain parameters required for design. according to the information collected during the construction process, for the construction of the diaphragm wall and full-cased piles, reduction in construction rate and over-excavation are likely to occur in such ground condition. however, the construction methods of diaphragm wall and full-cased piles still appear to be applicable in gravel conditions.
In the recent years, since the considerable human activities and limited open ground for the rails on the ground surface at metropolises in Taiwan, railways and metros have been constructed underground to provide high efficiency transportation networks. Diaphragm walls are constructed to stabilize underground constructions but they impede and change the direction of groundwater flow. The decreasing groundwater level at the downstream not only dries out neighboring wells and farmlands, but also salinizes soil at the coastal areas. On the other hand, the increase of groundwater level at the upstream raises pore pressure to magnify uplift forces and leakages of an underground structure and the potential of soil liquefaction.
This study describes the evaluating procedure and design concepts of Hanwa highway project in Japan to mitigate geotechnical problems induced by diaphragm wall constructions. In addition, the numerical simulation results of Kaohsiung subway project is also discussed as another case study for the future designs that will be conducted to the similar projects.
Undersea shield tunnel is a tunnel built under the seabed with shield tunneling technique. It is obvious that the construction risk of undersea shield tunnel is very different from its counterpart built in land. Risk management of the undersea shield tunnel construction must take specific geological and site conditions into serious consideration. Back analysis and reevaluation of the completed project are also imperative. This paper addresses the construction of Submerged Discharge Tunnel in Lungmen No. 4 Nuclear Power Plant Project in detail. The author hopes that this paper could help local contractors in upgrading the technique in undersea shield tunneling.