Design and Construction of Ho Chi Minh City Metro Line 1 Underground Section (Contract Package 1b)
Masrur Abdull Hamid Ghani, Kenichi Ito, Minoru Kuriki, and Shun Sugawara
ABSTRACT: Contract Package 1b (CP1b) is a part of Ho Chi Minh City Metro Line 1 (HCMC MRT Line 1) project which consists of underground construction of two stations, bored tunnels, cut-and-cover tunnel, and transition structure. Each structure has its own distinctive features due to its geographical condition, underlying geotechnical condition and construction constrain. Opera House Station, whose construction method categorized as deep excavation (up to 30 m depth) is the first underground metro station in Vietnam which is situated in a cramped downtown and surrounded by old-sensitive shallow-founded buildings. It was built by top-down method as the method offers better control of retaining wall deformation to minimize settlement of adjacent buildings. The other station, Ba Son Station, located next to the riverside, was protected by double sheet pile structure during its construction. For cut-and-cover tunnel, the rigid steel pipe sheet pile (SPSP) was used to maintain stability for construction in the river and on the weak alluvium clay soil. The underlying alluvium clay layers also cause a negative skin friction issue in the design of pile for the transition structure in Ba Son area. As for tunneling beneath the city, the bored tunnel using Earth Pressure Balance (EPB) Tunnel Boring Machine (TBM) was selected. The TBM was launched from Ba Son Station toward Opera House Station twice: one for the east-bound track, and the other is for the west-bound track. In this project, several instruments were deployed to monitor and to ensure the safety of construction works and surrounding buildings. The data from the monitoring works were also useful for back analyzing and reconfiguration of the construction method. Those features brought challenges for both design and construction stages. The design and construction experience of the project are shared in this paper.
KEYWORDS: Deep Excavation, Underground Station, Cut-and-cover Tunnel, Bored Tunnel, Monitoring
Big Challenges and Innovative Solutions at HZMB Link Project
L. Ming, Y. Haiqing, H. Sakaeda, and O. Ozgur
ABSTRACT: One of the world’s most challenging immersed tunnel projects, the Hong Kong – Zhuhai – Macau Bridge Link (HZMB) in the Pearl River Estuary, connecting Hong Kong Special Administrative Region (SAR), mainland China (Zhuhai) and Macau SAR, was completed and opened to traffic in 2018. It consists of 6km Immersed Tunnel with two artificial islands. Since the project was built in the open sea, the design and construction of the tunnel and artificial islands faced a series of grand engineering challenges. For example, the long distance ventilation and safety design, prefabrication of elements weighing nearly 80,000 tons each, foundation, siltation, towing and installation under high water pressure as well as construction of the west and east artificial islands. This paper discusses the major challenges faced during the HZMB Link project design and construction, and gives examples of innovative solutions to overcome those challenges.
KEYWORDS: Artificial Island, Immersed Tunnel, Foundation, Siltation
Lach Huyen Port Infrastructure Project and Soil Improvement Works
Thi Ha
ABSTRACT: To cover cargo demand in northern part of Vietnam and to fit large size vessel in marine transportation sector, an international deep sea port for 100,000 DWT size vessel is being constructed in Lach Huyen area situated at south east part of Hai Phong City. In this project, reclamation work is being conducted at Port Terminal Area and Access Road Area. In the construction area, totally 20m to 30m of fine soil (clay, slit and sandy clay) layers are distributed. To accelerate the consolidation and to reduce the residual consolidation settlement during port operation, soil improvement works are being carried out by cement deep mixing method and prefabricated vertical drain method. In this paper, overall construction project will be introduced in briefly and then soil improvement works will be presented.
KEYWORDS: Deep Seaport, Reclamation, Soil Improvement, Cement Deep Mixing Method (CDM), Prefabricated Vertical Drain Method (PVD) with Pre-loading
A Comparison of EPB and Slurry TBMs Operating in Mixed Ground Conditions Resulting from Tropical Weathering of Rock
J.N. Shirlaw
ABSTRACT: Deep, but uneven, weathering of rock is common in tropical and sub-tropical areas. Infrastructure development in many Asian cities has required tunnelling through weathered rock profiles. The ground conditions for the tunnelling typically include saprolite, rock, and mixed faces of soil and rock. Where the rock is strong, and mixed ground is anticipated to be encountered over a significant proportion of the drive, slurry TBMs are typically specified in Singapore, based on local experience. Case studies of slurry and EPB tunnelling in mixed ground conditions, from Hong Kong, are presented, and compared, to illustrate the issues involved. For the EPB drive, there were very large increases in the Penetration Index and Specific Energy when working in pressurised EPB mode in ground conditions comprising >50% strong or stronger rock. In these ground conditions the rate of disc cutter replacement was significantly higher than when tunnelling in open mode in a full face of rock, on the same drive. Average progress rates fell to less than 3m per week in the most extreme conditions of 85% to 99% rock, with most of the time being spent on interventions, including a significant proportion of time required to cool the excavation chamber. It is postulated that these observations are related to the clogging of the cut chips of rock in the tool gap, ahead of the cutterhead, when the cut rock becomes the majority of the spoil. A slurry shield in comparable conditions in Hong Kong did not experience the spikes in Penetration Index, Specific Energy, or cutter wear, in mixed ground conditions, that were experienced during the EPB drive.
KEYWORDS: Weathering, Tunnel, TBM, EPB, Slurry
Reuse and Recycling of Clayey Soil in Pasir Panjang Terminal Phases 3 and 4 Project in Singapore
Loh Chee Kit, Eugene Khoo, Seah Kim Huah, James Lam Pei Wei, Thiam Soon Tan, Fumitaka Tsurumi, and Takahiro Kumagai
ABSTRACT: In order to increase the handling capacity of ports in Singapore, the Maritime and Port Authority of Singapore (MPA) has embarked on massive port development projects for the past decade. One of the major projects was the Reclamation for Pasir Panjang Terminal Phases 3 and 4, completed in April 2015. The project provided 200 hectares of port land equipped with 5.7 km of berthing facilities to accommodate ultra-large container ships. In this project, MPA embraced sustainable development by reusing dredged and excavated clayey soil as reclamation fill and as fill material to form a containment bund within the footprint of the project. Nearly half of the reclamation fill consisted of clayey soil, which was improved using prefabricated vertical drains with surcharge. The containment bund, which served as a temporary earth-retaining system during reclamation filling, was formed using geotextile tubes filled with clayey soil treated with cement. This paper describes the innovative design and construction in the project.
KEYWORDS: Container Port, Reclamation, Dredged Material, Cement Mixed Soil, CMS, Containment Bund, Geotextile Tube
Performance of Cross and Buttress Walls to Control Wall Deflection Induced by Deep Excavation in Dense Urban Area
A. Lim and C. Y. Ou
ABSTRACT: The paper presents the performance of two deep excavation Case-histories and their three-dimensional finite element analyses. Case 1 describes the application of cross walls and buttress walls in controlling the diaphragm wall deflection and avoiding the low-story adjacent buildings from damages, in which those low-story buildings were founded on shallow foundations and located 1 to 2 m from the excavated area. Moreover, Case 2 demonstrates the application of cross walls and buttress walls to limit the movement of adjacent existing twin metro tunnels induced by deep excavation. In addition, the diaphragm wall of Case 2 defected due to heavy rain while concreting process and causing the excavation more challenging to be executed safely. Three-dimensional finite element analyses were conducted to simulate and examine the performance of cross and buttress walls to control movements induced by deep excavation. The result shows that the cross walls have a significant effect in controlling deformations induced by deep excavation. The dense interval between cross walls could yield a very rigid retaining wall system and cause very small wall deflections. The measure can be used for an excavation project nearby metro systems to reduce the potential settlement of the metro tunnels.
KEYWORDS: Deep Excavation, Wall Deflection, Cross Wall, Buttress Wall, Three-dimensional Analysis
Piled Raft Foundation with Grid-form Deep Mixing Walls Supporting the Largest Scale Base-isolated Building in Japan
J. Hamada, Y. Yamashita, T. Honda, M. Sugaya, and M. Kamimura
ABSTRACT: This paper offers a case history of a piled raft foundation with grid-form deep mixing walls (DMWs) supporting a 10-story base-isolated building of the world’s largest scale, measuring 340 m by 180 m in plan. The DMWs play the role of coping with liquefiable sand as well as of reducing settlement of soft cohesive stratum below the sand. Field monitoring of the settlement and the load sharing was performed for over seven years since the beginning of the construction in order to validate the foundation design. The measured settlement of the raft was 10 mm and the ratio of the load carried by piles to the effective structure load was 0.66 at 72 months after the end of construction. In addition to the long term monitoring, seismic measurements of the foundation were performed after the end of the construction. The incremental strain acts on piles, contact earth pressure between raft and soil or DMWs, water pressure beneath the raft and settlements under ground surface were measured during several earthquakes. These values roughly agreed with the design values. Consequently, it is confirmed that a piled raft combined with DMWs works effectively in liquefiable and soft ground.
KEYWORDS: Piled Raft Foundation, Ground Improvement, Load Sharing, Settlement, Seismic Observation, Base Isolated Building.
Piled Raft Foundation Supporting a Supertall Building in Osaka Constructed by Top-down Method
K. Yamashita, J. Hamada, and K. Hirakawa
ABSTRACT: This paper offers a case history of 300-m high building in Japan. Since the building has a five-story basement, a top-down method was adopted to carry out the underground construction works safely as well as to save construction time by simultaneous construction of the upper and the basement floors. To ensure high performance against strong earthquakes, piled raft foundation consisting of large-diameter bottom-enlarged cast-in-place concrete piles and steel H-piles built-in soil-cement wall (TSW) was employed as a cost-effective solution. In order to corroborate the foundation design, field monitoring on the settlement and the vertical load sharing between the piles and the raft was performed. Consequently, it was found that the foundation design was appropriate.
KEYWORDS: Supertall Building, Piled Raft Foundation, Top-down Method, Settlement, Load Sharing, Field Monitoring.
Anti-Seismic Numerical Analysis of Water Intake Structure of Pakistan Karachi K-2/K-3 Nuclear Power Plant
Wang Guixuan, Yin Xunqiang, and Zhao Jie
ABSTRACT: Based on the actual conditions of Pakistan Karachi K2/K3 Nuclear Power Plant (NPP), the special topic of seismic numerical simulation calculation and anti-seismic numerical analysis of water intake structure are introduced. Firstly, the project profile of K2/K3 NPP is briefly presented, including the preliminary design, the soil conditions of site, and the purpose and contents of the proposed special topics. Then, the physical and mechanical qualities of the foundation are introduced. Next, the method for calculating the designed ground motion parameters of engineering site are proposed and parts of results are listed which meet the provisions of standard and can be used as an input data for the anti-seismic analysis. Finally, anti-seismic analysis of water intake gate shaft, water intake tunnel, and diversion dike and bank revetment of water intake channel is described, respectively. Through the numerical analysis, it can be concluded that the design scheme put forward in the design can adopt appropriate reinforcement measures and the marine structure is stable under SL2 earthquake loading.
KEYWORDS: Pakistan Karachi K-2/K-3 Nuclear Power Plant, Anti-Seismic Analysis, Water Intake Structure, Seismic Wave Fitting
Application of Press-in Method to Coastal Levees in Kochi Coast as Countermeasures against Liquefaction
Y. Ishihara, H. Yasuoka, and S. Shintaku
ABSTRACT: There had been a concern that coastal levees in Kochi would lose their functions due to the settlement caused by liquefaction of the underlying ground as well as the wide-area ground subsidence of 2 meters in the coming huge Nankai Trough earthquake. Protected inlands were supposed to suffer from the long-term flood due to the succeeding tsunami. To cope with these problems, 13-kilometer-long levees in Kochi Coast have been appointed to be in direct control of Ministry of Land, Infrastructure, Transport and Tourism (MLIT), and have been under construction for seismic reinforcement. Requirements for this construction project were as follows: (1) levees have to be tenacious and their deformations have to be restricted below the allowable values, (2) construction should have minimal impacts on the surrounding environment and human activities, and (3) construction should be carried out at high speed and at low cost, even though cobbles and obstacles are contained in the ground. Under these requirements, reinforcement using sheet piles or tubular piles, along with the Press-in Method as their installation method, was chosen as a solution. This paper explains in detail the background and the decision making process of selecting the construction method for reinforcing the coastal levees in Kochi Coast, as well as the results of piling work in Nino and Nii sections.
KEYWORDS: Coastal Levee, Liquefaction, Tsunami, Pile Wall, Press-in
The Tangent Stiffness Uncertainty in Strain-hardening and Strain-softening Soil
Bengt H. Fellenius
ABSTRACT: Load distribution in piles can be evaluated from strain-gage records by applying the tangent modulus method to the measured strains. The method requires tests in soil exhibiting a plastic response to the relative movement between the pile and the soil. Where the response instead is hardening or softening with increasing movement, the evaluated pile material stiffness becomes larger and smaller than true, respectively. This is demonstrated by analysis of a hypothetical test on a pile with a constant stiffness (EA/L) tested in ideally plastic, strain-hardening, and strain-softening soil.
KEYWORDS: Pile Stiffness, Secant Method, Tangent Method, Plastic Response, Hardening, Softening
Application of Distributed Fibre Optic Cables in Piles
Jakub G. Kania, Kenny Kataoka Sorensen, and Bengt H. Fellenius
ABSTRACT: A high spatial resolution distributed fibre optic sensing system for measuring strain and temperature was used to instrument fourteen single piles subjected to general subsidence. Thirteen piles were driven (six steel and seven precast concrete) and one was a cased continuous flight auger pile, CFA. The CFA pile was subjected to a static loading test. The distributed fibre optic analyser measured the spectral shift in the fibre Rayleigh scatter to obtain strain and temperature data. The seasonal temperature changes in the surficial soil layers showed to influence the strain records. Several lessons were learnt from the application of distributed fibre optic sensors in piles, such as installation methods, influence of temperature, and performance of fibre optic cables.
KEYWORDS: Instrumented Piles, Distributed Fibre Optic Sensing, Rayleigh Scattering, Temperature Effect, Strain Gauges
Comparison of Flexural Stiffness between Hat-type and U-type Steel Sheet Pile Retaining Walls in a Field Test in Singapore
S. Moriyasu, S.P. Chiew, K. Otsushi, N. Matsui, S. Taenaka, K. Teshima, M. Tatsuta, and H. Tanaka
ABSTRACT: The use of the Hat-type steel sheet pile can potentially improve the performance of earth retaining walls because of two of its features: its wide width and location of interlocks. It can reduce the piling time and number of piles required for walls because of its 900-mm width, which is the widest among the hot-rolled monopiles in the world. Furthermore, Hat-type piles can achieve full-shear force transmission at the interlocks because their connections are located at the outer edge of the wall. This study focuses on the second feature, i.e., the interlock shear force transmission. The lateral load and excavation tests were performed to compare and verify the difference in the interlock behavior between U-type and Hat-type sheet piles. As the result, in contract to the reduction of shear force transmission of the U-pile wall, the Hat-pile wall exhibited high flexural stiffness because the interlocks achieved the full-shear transmission mode.
KEYWORDS: Steel Sheet Pile, Retaining Wall, Interlock Shear Force Transmission, Lateral Load Test, Excavation Test
