Following the international trend, the development of the domestic design codes of engineering structures gradually moves towards performance based design. For a reference to the development of the performance based geotechnical design code, this paper introduces the Japan design code of railway foundation structures with a complete framework of performance-based design. Based on the evaluation items specified in the code, this paper also provides an illustrative example to demonstrate the procedure of seismic performance evaluation for a bridge group pile foundation using a pushover analysis.
In recent years, major design codes around the world have adopted a performance-based design approach. However, most of the design of underground structures is still implemented based on the traditional force-balance method with a specified factor of safety. Japanese Railway Technical Research Institute is one of the pioneers to utilize a performance-based design code for underground structures, where specific performance objectives and verification methods have been developed. Furthermore, applications of the simplified method with free-field racking deformation imposed on underground structures have been canceled and replaced by a non-linear push-over method to verify structural performance under seismic loading conditions.
This paper presents the design of underground structure of a Jakarta MRT project utilizing the Japanese performance-based design code. The design process, planning, major parameters determinations, acceptable level assignments, and verification methods are introduced in the paper. The response of structures obtained from both the simplified method and the non-linear push-over method are compared and discussed.
In Taiwan, 70% of the area is covered by mountain. With excessive developments of the land area, developments of the mountainous regions have emerged, demanding slope stability analysis and design. Although most of the factors, required to conduct a numerical analysis, were considered in the past, the evolution of the other countries' normative design methods has led to the increased requirement for considering performance design and unified computing methods under globalization. The European Code Committee and Japan's design specifications point out that the importance of the design target can influence the design requirements. This paper focuses on slope analysis and introduces the influence of groundwater level elevation on slope stability in rainfall and sliding conditions. The 10-year monitoring condition illustrates the problems and solutions that may be faced in accordance with the current slope design code. Lastly, a partial coefficient method was utilized to analyze the slope safety factor under the aforementioned conditions.
The geotechnical engineering design in Macau is primarily to follow the Regulations on Foundations1 and the Regulations of Earth Retaining Structures and Earthworks2 issued by the Macau Government and supervised and executed by the Land, Public Works and Transport Bureau (DSSOPT3). In order to harmonize with the Regulations on Safety and Loading in Structures of Buildings and Bridges4 followed by structure design, a limit state design (LSD) referred to the frameworks in Euro Code 7 was introduced where limit states were regulated as a basis for safety checks. It is a different concept from the allowable stress design (ASD) or working stress design (WSD) that has long been the local practice for geotechnical engineering design in Taiwan. This paper first overviews the design framework of geotechnical engineering in Macau. It then emphasizes in more details on the pile design, and a comparison is made between Macau and Taiwan codes. An example in the Macau Light Rapid Transit (LRT) Phase 1 projects is illustrated at the end to show the differences in pile design results between Macau and Taiwan codes and to provide as a reference for the society.
1: direct translation from its original Portuguese “Regulamento de Fundações”.
2: direct translation from its original Portuguese “Regulamento de Estruturas de Suporte e Obras de Terras”.
3: abbreviation from its original Portuguese “Direcção dos Serviços de Solos, Obras Públicas e Transportes”.
4: direct translation from its original Portuguese “Regulamento de Segurança e Acções em Estruturas de Edifícios e Pontes”.
The rational application of risk management (RM) is critical for the long-term safety and operation of geotechnical systems. This paper has summarized the contributions and problems of the RM during the past 10 years in China mainland. The RM is evident as an effective solution to reduce the disaster and death during the construction and operation of geotechnical systems. However, the RM that is used in current practice lacks the risk control, the benefit explanations, and the post-disaster evaluations when compared to the risk assessment, the loss descriptions, and the pre-disaster evaluations, respectively. In fact, the enhancement of the quantitative risk assessment and the establishment of a resilience evaluation model post-disaster would be effective. Thus, a lifetime risk management framework that can simultaneously consider risk, resilience, and robustness was proposed in this paper. Within which, the resilience model can optimize the resilient ability of the geotechnical structure and the corresponding cost after a low-chance and high-impact risk event; the robust design can reduce the risk before an event and increase the resilience after the disaster happens.
In practice, transformation models are frequently used to estimate the design soil/rock parameters at a design site empirically. Many transformation models were developed from databases of properties based on specific geomaterial types or specific locations. Like any empirical approach, it is not judicious to apply transformation models to other sites without a proper characterization of site conditions and geology. In the current paper, global multivariate soil and rock databases are presented, and the biases and variability in several transformation models are calibrated to the global databases. The calibrated models are more “generic” and broaden the range of conditions where transformation models may be used through bias and uncertainty corrections.
Many studies in the world use the TRIGRS program to conduct a regional landslide stability analysis under rainfall. This program, developed by the USGS, is capable of analyzing the time dependent safety factors for an infinite slope during continuous rainfall infiltrations. The analytical solution of a one dimensional rainfall infiltration given by Iverson (2000) is the key part of the TRIGRS. The lack of solution details in his original paper resulted in some coding errors in the early version of the TRIGRS (2002). Although some researches have revealed the errors in the program, the rigorous derivation of the one dimensional rainfall infiltration is still not found in relevant papers to the authors’ knowledge. This study aims to thoroughly derive the analytical solution and examine the relation between the theory and program. The results show that the saturated model, used in the newest version of the TRIGRS (2008), is based on a correct analytical solution derived from this study. The discrepancy of safety factors by using different versions of the program is large enough to misjudge the result of landslide stability assessment. It is concluded that the TRIGRS (2008) is the correct one and should be adopted by users in the future.
The 0206 Hualien earthquake occurred in northeastern Taiwan at 23:50 on 6 February 2018. The epicenter of the earthquake was at 24.1°N and 121.73°E with a focal depth of 6.31 km and a magnitude 6.26 (ML). The seismic intensity was up to Level 7 in the seismological station of Hualien City. It caused building collapses and 17 fatalities in Hualien. There were many foreshocks and aftershocks in this event. Although the strong motion duration is only about 10 sec, many areas, from the Huaxi road located at the Milun Fault zone to Bengkan along the Lingding Fault at a farthermost distance around 30 km from the epicenter of the earthquake, were subjected to soil liquefaction.
According to the reconnaissance survey, the main area suffered from the soil liquefaction damage was about 0.2 km2 and was in the range near the front exit of the Hualien Train Station. The sites with obvious liquefaction evidences, including the ground settlements and tilting of buildings, were located from Guolien 5th Rd. to Guosheng 7th St. in the west-to-east direction, and Shangxiao St. to Guosheng 8th St. in the south-to-north direction. Four types of failure modes were identified, they include: foundation failures of building and harbor facilities, lifeline damages, damages of earthworks and pile foundation of the bridge, and lateral spreading and flow failure. The survey indicated that the effect of pre-shaking on the triggering of liquefaction is very important. Moreover, the probable effect of seismic amplification on structural safety at liquefied sites is observed. Therefore, more efforts should be required to strengthen the related researches, such as liquefaction mechanism, hazard analysis, retrofit and countermeasures for disaster reductions, to prevent or mitigate the possible damages induced by soil liquefaction.
Facing the adverse natural environment and the lack of materials from the surrounding island, it's difficult to execute the construction project of the Kinmen Bridge. This paper documents the experience of the Kinmen Bridge construction focusing on the reverse circulation of the pile's construction in the deep trench area. It is hoped that this paper would serve as a reference to the future sea-span bridge construction.