Discussed herein are the challenges met in the underground constructions of two major infrastructure projects carried out in recent years in Taiwan, i.e., Taoyuan International Airport Access MRT System and the Green Line of the Taipei Metro. Taoyuan International Airport Access MRT System is an airport link transit system connecting the Taoyuan International Airport with surrounding transportation hubs. To avoid the high risk of constructing crosspassages under water, a Double-O-Tube (DOT) shield machine was successfully adopted for the very first time in Taiwan for tunneling the section of the route under the Tamsui River. For constructing Taipei Main Station, pumping with a record high flow rate was carried out to lower the piezometric head in the underlying gravelly water-bearing stratum in order to maintain the stability of the bottom of excavation. While constructing Beimen Station of the Green Line of Taipei Metro, a historical building, which was designated as a cultural heritage by Taipei City Government, had to be temporarily relocated before construction and moved back to its original location after the station was completed. Furthermore, the shield machines in the two tunnels had to go through two SMW walls and one diaphragm wall underneath existing tunnel boxes of Taiwan Railways and High Speed Rail. Extensive ground treatment was carried out to enable openings to be made on these walls for the shield machines to go through and the H-piles in one of these walls to be removed.

抄録全体を表示

The project of railway tunnel construction across the Bosphorus Strait in Istanbul, Turkey is known as one of the most interesting projects that connects Asia with Europe, and consists of tunnels constructed in three different methods: immersion, TBM and NATM. Istanbul is the largest city in Turkey with a population of over 15 million. And this city is divided by Bosphorus Strait. With only two east-west bridges connecting European side and it Asian side, this resulted in chronic congestion with increased air pollution. To relieve these problems, construction work on a subway tunnel under the strait was begun in 2004 under an EPC (Engineering, Procurement, and Construction) turnkey contract with Japanese financial backing. This concept was imagined 150 years ago in Turkey and we can see from the design drawing illustrated by a civil engineer in 1860.

抄録全体を表示

This paper describes the foundation design process that has been adopted for some of the world’s tallest buildings, including the Burj Khalifa in Dubai and the Incheon 151 Tower in Korea. The foundation system for these super tall towers is a piled raft, founded on deep deposits of soils and rocks. The foundation systems are required to support the large building vertical and lateral loads and to restrain the horizontal displacement due to wind and seismic forces. The behavior of the foundation system due to these loads together with the foundation stiffness influences the design of the superstructure, displacement of the tower, as well as the raft foundation. Therefore, the design takes into account the interactions between soil, foundation and superstructure, so as to achieve a safe and efficient building performance. An outline will be given of the geotechnical investigations completed, the field and laboratory testing programs, and the design process. Of particular concern for the Burj Khalifa was a potential issue of cyclic degradation of skin friction. The measured and predicted building settlements will be presented. For the Incheon 151 Tower, complex ground conditions were present under the site which resulted in significant challenges for pile design and construction.

抄録全体を表示

The Hong Kong-Zhuhai-Bridge Project, being situated in the waters of Lingdingyang of the Pearl River Estuary, is a mega sea-crossing infrastructure project currently under construction in the Pearl River Delta of China. It consists of a series of bridges, sub-sea tunnels, viaducts and artificial islands connecting the Hong Kong Special Administrative Region ("Hong Kong"), Zhuhai City of Guangdong Province ("Zhuhai") , and the Macao Special Administrative Region ("Macao"), three major cities situated on the Pearl River Delta of China. The functions of the Project are: (1) to meet the demand of passenger and cargo interflows among Hong Kong, Mainland China (particularly the western Pearl River Delta region) and Macao; (2) to establish a new land transport link between the east and west banks of Pearl River; and (3) to enhance the economic and sustainable development of the three major cities in the Pearl River Delta region. The geotechnical works associated with the Project, including reclamations, onshore and offshore foundations, sub-sea tunnels, artificial islands, earth retaining structures and roadworks are extensive, large-scale, diversified, challenging and complex. In this special lecture, the background of the mega project and pertinent geotechnical works of the Project, in particular components contributed by the Hong Kong Special Administrative Region Government ("HKSARG"), are described. Moreover, green measures implemented to reduce environmental impacts during the design and construction stages of the Project are also presented.

抄録全体を表示

In August 2010, the fourth runway called D-Runway (2,500-m long) was completed off the shore of the Tokyo International Airport (Haneda Airport), which is the fourth largest airport in the world in terms of passengers handled. Since the D-Runway is situated at the mouth of the Tamagawa River, a hybrid structure combining a piled-elevated platform and land reclamation was planned so that it would not obstruct the flow of the river. In the reclamation area, a slope-type rubble mound seawall was constructed on the soft clay seabed, which was improved using the sand compaction pile method, with a total of 52 million cubic meters of soil, sand and rock used in the land reclamation. The piled-elevated platform is a massive 520,000-m2 structure in which 198 prefabricated steel jackets supported by 1,165 steel-pipe piles were connected together by welding on site. This project required huge quantities of construction materials, including 470,000 tons of steel and 450,000 m3 of concrete. The D-Runway was successfully constructed in just three and a half years thanks to the rapid construction method and a continuous 24-hours-a-day work schedule. This paper outlines the D-Runway project and its main structures.

抄録全体を表示

As a result of The Great East Japan Earthquake, approximately 28 million tons of disaster wastes (such as disaster debris and tsunami deposits) were generated in the three prefectures of Iwate, Miyagi, and Fukushima, mainly due to the tsunami. The waste treatment on this massive scale would normally take more than a decade. For the local recovery and reconstruction, disaster waste treatment was the first step, and its early treatment was essential. Two months after the disaster, the government prepared a master plan for completing the treatment by the end of March 2014, approximately three years after the earthquake, focusing on recycling of the waste. Due to the enormous amount of waste and its complicated physical properties, disaster waste treatment posed a number of problems. However, the construction industry and related parties worked on the task with a sense of mission, completing the treatment in Iwate and Miyagi prefectures by the end of March 2014, as specified by the national government, and achieving a recycling ratio of nearly 90% based on thorough recycling and reuse. Materials recycled through treatment were used for embankment and backfilling, etc. in public reconstruction projects.

抄録全体を表示

This paper identifies the challenges and opportunities for disaster waste recovery and utilization in developing countries. In the introductory part, various types of disasters and related waste streams are identified. The first part of the paper highlights the four-step disaster waste management strategy. The first step is prevention strategy to take measures which can reduce the incidence and impact of the disaster waste. The second step is the preparedness strategy to plan for disaster waste removal, storage and recovery in case there is a disaster. The third step is removal strategy to sketch different scenarios with possible measures to promptly remove disaster waste to make a way for rescue and relief operations. The fourth and final step is recovery strategy to develop comprehensive plan for recovering materials and energy from disaster waste that may also be vital for the relief and reconstruction activities. Thereafter, concept of holistic waste is coined to integrate disaster waste management into regular waste management system for efficient and effective delivery. The second part of the paper identifies the challenges and opportunities for disaster waste recovery and utilization in developing countries. To recover and utilize disaster waste the basic pre-requisites are capacity and awareness, policy and institutions, and technology and infrastructure. The awareness at community and political level plays a vital role while the technical and financial capacity are the key requirements for the successful recovery and utilization of disaster waste. Policy framework and institutional arrangement is important, especially for prompt removal and storage of disaster waste (debris/rubble) as the situation just after disaster is very sensitive. Last but not the least, technology and infrastructure are essential for efficient recovery and utilization of the resources from disaster waste. The third part of the paper reviews the current situation of disaster waste management in Nepal after two devastating earthquakes. The data for the volume and composition of disaster waste in Nepal is being estimated as many buildings, which are badly damaged, are yet to be demolished. The data collection is a major challenge in many countries including Nepal due to limited resources, difficult terrains, and change in government’s post-disaster priorities for relief operations. To support the disaster waste management in Nepal, UNEP IETC has started a comprehensive technical support. The fourth part of the paper provide information regarding UNEP IETC and its current projects including for disaster waste management. UNEP is supporting a comprehensive national waste management strategy for Nepal that will also include disaster waste management. The last part concludes the paper by emphasizing on the important factors to develop effective disaster waste management strategy and operations. These include the availability of local project teams with technical staff and laboratory, resources, stakeholder cooperation, teamwork among various levels of governments and international partners, and all the four steps for disaster waste management should be given proper importance instead of just focusing on disaster waste recovery and utilization.

抄録全体を表示

Due to the 2011 off the Pacific Coast of Tohoku Earthquake, a large scale tsunami hit the Pacific coast area of the Tohoku and North-Kanto Regions, Japan. As a result of the earthquake and the subsequent tsunami, the tsunami-related sediments of about 900,000 tons were generated in Kesennuma City, Miyagi Prefecture. Therefore, the tsunami-related sediments had to be properly treated from the viewpoint of being recycled as non-toxic geomaterials and certainly utilized as embankments or filling materials in reconstruction projects. Additionally, it was required that they were quickly treated in order to preserve the living environment of local inhabitants and to improve the public health. In a disaster waste management project by the Miyagi prefectural government in Kesennuma (Kesennuma treatment area), the treatment (soil modification, separation, immobilization, etc.) and recycling of tsunami-related sediments were completed in about one year. This paper summarizes the outline of the treatment of tsunami-related sediments and describes the geotechnical properties of recycled geomaterials in the Kesennuma treatment area.

抄録全体を表示

Management of disaster debris treatment may include (1) progress in several work with over 100 laborers, (2) control of various mechanical equipment and machineries, (3) operation of more than 200 trucks. In order to properly support this management, Okumura Corporation has developed the “Disaster debris Treatment Support System (DTSS)” in 2011. DTSS has been accumulated a large amount of integrated data on disaster debris treatment in Yamada town, Iwate prefecture. 240,000 unit data obtained by the DTSS were analyzed to reveal the physical properties of debris and tsunami deposits. These data were too huge to analyze effectively. Spreadsheet software usually cannot be calculated 100,000 or more data. We solved this problem by applying a practical analysis software. The software called “Tableau” can be efficiently analyzed 100,000 or more data. The huge data was analyzed with Tableau. Results of the analysis of applying the Tableau revealed several weight characteristics of the transport phase in the debris and tsunami deposits. The results obtained will be expected to effective use as an experience to the time of future catastrophe.

抄録全体を表示

The Ochanomizu Sola City building is one of the largest redevelopments in which existing bored cast-in-place piles have been used in combination with new bored piles for the foundation of a new high-rise building in Japan. The building, completed in 2013, is a 110-m high-rise office building supported by 169 existing bored piles and 99 new bored piles. In addition to the existing piles, the existing foundation slab and pile caps were also reused. During the demolition of the old building, which was constructed in 1983, several types of investigations of the existing piles, including two pile load tests, were conducted to assess their integrity and performance. In the design stage, the safety of the mixed foundation system subjected to vertical and horizontal loads was verified using detailed analytical methods. It was also estimated that approximately 4,000 tons of CO2 were saved by reusing the existing piles. The measured settlements and vertical sharing loads of the existing piles were found to be in reasonable agreement with the predicted results.

抄録全体を表示

A case history of the piled raft foundation for Shanghai World Financial Center which is a 101-storey, 492 m high building is presented in this paper. To monitor the performance of the piled raft foundation system and to verify the foundation design work, field measurements were carried out on the raft settlements, pile head axial loads, contact pressures of the raft and pore-water pressures underneath the raft during the entire construction period. The measured raft settlements were comparable to the computed results. At six months after topping out, the maximum settlement was 130 mm in the tube area, decreasing to 90 mm at the edges. Axial loads at pile head increased gradually and varied in magnitude from 1000 to 5000 kN, less than the proposed compression capacities of the steel pipe piles. Both contact pressures of the raft and pore-water pressures beneath the raft varied considerably during the initial construction period but changed slightly after the end of construction. Based on the field measurement results, the piled raft foundation design proved to be appropriate.

抄録全体を表示

This paper offers a case history of the tallest building in Japan, 300 m in height above the ground level, located in Osaka, constructed by top-down method. The foundation of the building is a piled raft foundation which consists of a raft foundation with its bottom depth of 30.5 m below the ground surface and cast-in-place concrete piles embedded in very dense gravel layer below a depth of 70 m. The top-down method enables to make deep excavation safely in consideration of the surrounding environment and construct upper and basement floors simultaneously. Field monitoring were performed on the settlement and the load sharing of the piled raft. It was found that the measured settlements and load sharing between the piles and the raft roughly agreed with the design values.

抄録全体を表示

Kuala Lumpur Limestone formation exhibits karstic features with irregular bedrock profiles and variable weathering condition. The Klang Valley Mass Rapid Transit (KVMRT) SBK Line project is the first Mass Rapid Transit project in Malaysia. There are three underground stations namely Tun Razak Exchange (TRX) station, Cochrane Station and Maluri Station located in Kuala Lumpur limestone formation. TRX Station is the deepest station with maximum excavation depth of 45m below ground and also one of the underground interchange stations for future line. Cochrane Station with maximum excavation depth of 32m below ground also serves as launching shaft for the tunnel boring machine from both ends of the station. Maluri Station with maximum excavation depth of 20m below ground includes an underground train crossover as operational requirement. A technically appropriate and cost effective temporary earth retaining system suitable for the challenging geological formation using secant pile wall supported by temporary ground anchors or temporary strutting was adopted. High ground water table is also a challenge for the deep excavation. Rock grouting was carried out to prevent water ingress through rock fissures and cavities into the excavation pit as well as to prevent excessive ground settlement and occurrences of sinkholes surrounding the excavation area due to groundwater drawdown. Vertical rock excavation adjacent to the retaining wall involving rock slope strengthening works, surface protection, controlled blasting and vibration control was successfully designed and implemented. Temporary traffic decking on top of underground station was designed in order to maintain the traffic flow during the station excavation works. This paper presents the design of the temporary earth retaining system together with vertical rock excavation to the final depth of the station in karstic limestone formation. The unique experience (design and construction) gained from this project will be useful reference for similar excavation works, especially in mature karstic limestone formation.

抄録全体を表示

The Bendemeer Station project is part of the construction of MRT Downtown Line 3 (DTL-3) in Singapore, under Contract C933. High variation in geological condition along the alignment was encountered during the tunneling works in this project. The transitions from Old Alluvium soil towards the soft soils of Kallang Formation create the challenging mixed-face soil condition at the tunnel face. This sudden change of tunnelling medium creates the difficulties to control face pressure and over excavation which can cause substantial ground loss and movements. This paper mainly focuses on the ground responses caused by twin bored tunnelling under mixed-face soil condition and the implementation of building protection measures to the existing late 19^th & early 20^th centuries shophouses which the tunnel had undercrossed in mixed-face soil condition.

抄録全体を表示

For the construction of the Central Circular Shinjuku Route the shield-tunneling method was adopted for approximately 70% of the route to mitigate the impact of construction on the neighboring environment and traffic flow. The turnoffs and entrances/exits were constructed using an innovative method. After completion of the shield tunnels for the main roads, the cut and cover method was used to construct the concrete bodies of the turnoffs and entrances/exits. These concrete bodies were connected to the shield tunnels by cutting through the steel segments. This method was employed after sufficient consideration. Some of the geotechnical issues are shown in this paper.

抄録全体を表示

Due to degradation in quality of ground improvement during tunnel excavation, shield machines arriving at the receiving shafts have been one of the most risky works in soft ground tunnelling. The situation will become more challenging if the destination is not a shaft but an operating station. This paper illustrates a case study in the Taipei’s Mass Rapid Transit (MRT) projects where, due to limited space and intricate pipeline system above the designed route, constructing a receiving shaft next to an operating station for shield tunnelling is not economically available. As a result, the tunnels should be connected to the station directly with limited protection from the improved ground that was implemented at the breaking area. The background of the study case is first briefed, including the restraints to keep the station in revenue operation. The construction procedure is then provided to delineate how the breaking-through process is incorporated with complementary grouting, machine disassembly, and lining erection. Through the results of the monitoring system that includes electronic instruments, the case is completed under reasonable control of construction-induced ground and structure deformations, dust, and etc. The operation of the station is not interfered at all over the breaking-through process.

抄録全体を表示