Geotechnics and Earthquake Geotechnics Towards Global Sustainability

As an introduction of Geotechnics and Earthquake Geotechnics towards Global Sustainability, this chapter reviews the fundamentals of global sustainability, including the status of climate change and the concepts of growth limits, strong and weak sustainabilities, and an ecological footprint. Based on this review, a conceptual framework of global sustainability is proposed as follows. Because humanity’s burden has already exceeded Earth’s biological capacity, an increasing number of regional systems may face critical conditions. Thus, studying the vulnerability and robustness of social networks and ecosystems is crucial in establishing a strategy to achieve sustainable development. The risk assessment approach combining the uncertainties in fragility and hazards is readily applicable to form a reasonable strategy in the adaptation and the risk management to the global climate and environmental change. In conventional design, construction of a good geotechnical work was the sole objective of design. In the merging trends in design for sustainability, providing appropriate function and service rather than the construction of a solid structure becomes the final objective of design. A new challenge is combined hazards, such as the combination of earthquake motions and tsunamis observed during 2004 Sumatra, Indonesia earthquake. Thus, radically new approaches and technologies must be developed in the near future.

Sustainability is a vague all-encompassing concept that increasingly influences industrial and social actions and is a controlling element in many major engineering projects. This chapter focuses on the mitigation of threats to sustainability by earthquakes. There are two components to mitigation; providing structures by appropriate resistance to earthquake shaking and minimization of deaths and suffering by cost effective emergency response. Both aspects of mitigation will be illustrated by recent innovative engineering developments in the context of major projects; retrofit of 800 schools within a 15 year period, and the development and application of a real time post-earthquake decision model for dealing with national emergencies. This model is currently being employed to evaluate various threats from a natural disaster to a terrorist act during the 2010 Olympic Winter Games in Vancouver.

The sustainability of megacities and the ecosystems they influence are critical for ensuring quality of life and environment throughout the world. This sustainability requires infrastructure systems that provide a good and equitable quality of life, and a balance between consumption, disposal, and environmental capacity. Megacities must be strengthened and prepared to resist all hazards that may threaten them. Megacities function as a mega-system made up of many independent subsystems that have been developed in silos. However, the operations of each system depend upon other subsystems within the mega-system, under both extreme and usual circumstances. Lifeline systems are the basic infrastructure that supports all other systems needed for a megacity to function properly. The resiliency of lifeline systems is critical to the sustainability of megacities. Future directions in lifeline systems require improved interactions between the interdependent systems and improved inter-agency coordination. Megacities are extremely vulnerable to risks from natural and man made hazards. Transformative research is needed to better understand how interdependent systems interact and to develop decision support tools that help to understand the performances of complex systems under normal and extreme events. Examples from the Los Angeles megacity region are presented to show the makeup of megacities and mega-systems, and to illustrate their vulnerabilities to extreme events. The simulated performance of water supply and distribution systems in Southern California during a great earthquake scenario are summarized to show how advanced decision support tools may be used for improving the functionality of critical infrastructure systems under normal and extreme circumstances. This study indicates that resilience can be enhanced through multi-system integration and the risks and vulnerabilities to hazards can be overcome through integration of existing infrastructure.

Construction of geotechnical structures produces various environmental impacts. These include depletion of limited natural resources, generation of wastes and harmful substances during material productions and construction, ineffective usage of energy during processing of raw materials into construction materials, and emissions of unwanted gasses during transportation of materials and usage of equipments. With increasing interests in sustainability at the global scale, there is a need to develop a methodology that can assess environmental impacts at such scale for geotechnical construction. Using embodied energy and gas emission, quantitative measures of environmental impact are evaluated using a case study of a new high speed railway line construction in the UK. Based on the results, the keys to energy savings are (a) to optimise the usage of materials with high embodied energy intensity value (b) to optimise the transportation network and logistics for processes using primarily low embodied energy intensity materials and (c) to reuse as much materials on-site as possible to minimise the quantity of spoils or distance to disposal sites. The evaluated embodied energy and embodied carbon values are compared to those of other types of structures and of other activities and carbon tax values. Such comparisons can be used to discuss among various interested parties (clients, contractors, consultants, policy makers, etc) to make the construction industry more energy efficient.

In the UK today, sustainability is seen as embracing a wide range of issues that engineers have to consider in projects, from biodiversity to employment. Sustainability risks becoming diluted to the point that it represents “business as usual”. The consequence of the Copenhagen summit of December 2009 for the engineering profession may be that we start to see carbon as a primary design determinant, not simply as one of a list of desirable environmental outcomes to be traded one against the other. As a proxy, carbon is now providing the focus for political action that sustainability could never achieve. In this context, arguments over climate change science and the extent of man’s contribution to global warming have become irrelevant. The much quoted 1987 Brundtland Commission definition of sustainability as “development which meets the needs of the present without compromising the ability of future generations to meet their own needs” is unhelpful in the sense that it sets no base standard against which the engineering profession can deliver buildings and infrastructure that will have an impact over many future generations. It is imperative politically that public confidence is maintained in any lifestyle changes that may be required over the decades ahead. A more useful definition of sustainability for policy makers and the engineering profession would reflect the importance first, of technological innovation and second, of setting a baseline for engineers to design against: “Sustainability is managing our use of resources, energy and human capital to ensure that future generations have the potential to enjoy a quality of life at least as good as our own”. For the geotechnical engineering community, the key issue for debate will be how the emerging low carbon economy will affect the design and delivery of low-carbon infrastructure, such as transportation projects, renewable energy or a new generation of nuclear power plants. The maintenance and upgrading of existing infrastructure , such as water and waste water systems, road and rail infrastructure or flood and landslide protection will also require fresh thinking to minimise use of materials, energy and labour. The challenge for geotechnical engineers is to recognise that after years of important but low level commitment to sustainable engineering solutions, very soon we will be required to design, to tender, to construct and to operate our buildings and infrastructure not only within the usual constraints of time and money but also within the constraints of carbon accounting. For geotechnical engineers around the world this will require new models, new tools and new training, all of which need urgent research and rapid implementation.

Two case studies are described in terms of sustainable conservation of cultural heritage as well as social development in the World Heritage Site of Angkor, Cambodia. These problems are very unique in a sense that the phenomena were found quite different from what geotechnical engineers had been used to expect in daily practice. A tower of masonry structure that JSA (Japanese Government Team for Safeguarding Angkor) selected for structural conservation was inclined about 5 degrees. Since the deformation of the step stones showed the same inclination, tilting of the foundation was considered as major mechanism for the inclination of the Tower. After trenching of the soil mound, the compacted soil layer was not inclined but horizontal. This was quite different what we had expected. What was the mechanism to cause the inclination? Further study revealed that the slip-down of the side step stones along the foundation platform was the true mechanism. JICA (Japan International Cooperation Agency) made a study of water resource from pumping underground water. They have monitored seasonal fluctuation of shallow water level at more than 50 surface wells and tried to simulate the seasonal changes caused by horizontal flow from higher mountain to lower lake zones. Finally, JICA had installed a facility to pump water more than 8,000 ton/day. After the pumping started, a monitoring well at 3 km from pumping zone showed 1 m of drawdown of water level that was predicted as little effect by the simulation. Since the plain in Angkor has very gentle slope of the order of 0.001, horizontal flow of underground water is very slow and negligible. The seasonal changes of the water level of 4– 5 m was caused not by horizontal flow but infiltration of rain water and evaporation water from the deep layers that was not included in the model JICA used.

In recent years, global warming has caused the sea level to rise. The river or coastal related disasters such as tsunami, cyclone and flood have also become higher in frequency and stronger in intensity. As one of the counter measures, some of the existing coastal protection structures need to be rehabilitated and new, stronger or taller coastal structures have to be built. How to construct coastal protection structures in a quicker and yet cost-effective way becomes a challenge to geotechnical engineers. The coastal protection structures can be classified into different categories according to the materials used. In this chapter, several new construction methods for coastal protection structures will be presented. These include the use of geo-tubes, geo-bags, geo-mattresses, geo-containers, precast concrete segments, suction caissons and assembly structures. The applications of some of these new techniques in the construction of coastal protection structures are illustrated using case histories.

This chapter presents research works carried out in developing the latest spectral hazard maps proposed as input for revision of Indonesian Earthquake Resistant Building Code, the SNI 03-1726-2002. Improvement in seismic hazard analysis and careful inclusion of recent seismic records were augmented. Seismic sources were modeled by background, fault, and subduction zones considering truncated exponential model, pure characteristic model or both. Several well-known attenuation functions were selected including the Next Generation Attenuation (NGA). Maps of Peak Ground Acceleration (PGA) and Spectral Response Acceleration (SRA) for 0.2 s (short periods) and 1.0-s period for 2% probability of exceedance in 50 years were developed using PSHA. Additional geotechnical and tsunami hazard assessment researchs for Banda Aceh city, the capital of Aceh Province were also submitted. The results of site response analysis and liquefaction study at several points were utilized to generate contours of acceleration, amplification factor, design response spectra, and potential of liquefaction for Banda Aceh. The tsunami hazard study was conducted using mathematical simulation and modeling leading to estimate the potential tsunami that may occur in the future which covers tsunami inundation, run-up, and developing tsunami zonation map. The output of geotechnical and tsunami hazard assessment was then overlayed on top of the land use city planning in a Geographical Information Systems (GIS) database and used as criteria for tsunami warning system, an input in developing land use management for Banda Aceh, and enriching the basic regulation for new infrastructures and local building codes.

Seismic microzonation and earthquake loss estimation scenarios are needed for city planning, disaster preparedness, risk reduction and hazard mitigation decisions, and urban rehabilitation actions in earthquake prone areas. Loss estimation due to earthquakes in an urban environment is a very complex process that requires detailed building inventories, realistic estimation of earthquake characteristics on the ground surface and comprehensive assessment of building vulnerabilities. The earthquake hazard is spatially distributed in relation to earthquake sources that need to be assessed based on the regional seismotectonic scale and local site conditions. Mapping the variation in earthquake hazard at an urban scale makes it possible to select relatively less affected zones for the allocation of appropriate land use. Urban development patterns can be oriented toward these relatively less affected zones to minimize possible earthquake damages. The three principal factors controlling earthquake loss are earthquake source characteristics, site response and structural features. The seismic microzonation maps would indicate the distribution of site response with respect to ground shaking intensity, liquefaction and landslide susceptibility; thus providing an input for urban planning and earthquake mitigation priorities at an urban scale. It is also possible to estimate building damage and causalities based on microzonation maps used as an input to earthquake damage scenarios. These estimates may be very approximate and may not always be on the conservative side based on the accuracy of the input data and methods of analyses. However, they can also be more realistic and more accurate when more comprehensive data and more sophisticated analysis methods are implemented. Thus one of the important issues is the estimation of the needed accuracy and corresponding level of complexity in the analytical studies. The results obtained using different levels of seismic hazard and site characterisation data will be summarised very briefly to demonstrate the importance of the comprehensive site characterisation as well as the procedures used to estimate site effects for different levels of seismic hazard based on case studies conducted in Istanbul.

On October, 1 2009 a heavy rainfall hit the limited area on the N-E part of Sicily (Italy) near the town of Messina. At the station of St. Stefano di Briga a rainfall of 223 mm occurred in 7 h with a peak of 10.6 mm in 5 min. During the event many landslides such as sliding, debris flows and mud flows occurred in the 14 villages, causing 37 victims, mainly in the villages of Giampilieri and Scaletta Zanclea. Big damage occurred to the buildings, as well to roads and railways. The event caused about 1,652 homeless and the total cost for the recovery was estimated in about 800 M U.S. dollars. The microzoning of residual risk allows about 50% homeless to come back in the houses located in areas at very low risk. The assessment of the slope instability could be done by empirical correlation or analytical and numerical analyses. Some criteria for the stabilization works for risk mitigation are discussed. As the damaged area is prone to seismic risk (it was shaken by the 1908 Messina and Reggio Calabria earthquake), the analysis of slope instability and the evaluation of the behavior of the stabilization works must take into account the multidisciplinary risk analysis due to heavy rainfall and earthquakes.

On August 8th, 2009, Typhoon Morakot invaded Taiwan and had caused serious damages to south of the island. A major portion of highway bridges located in the affected region were suffered from various natural hazards, such as slope failures, debris flows, floods, and scours. Despite the depressing fatalities and infrastructure damages, Typhoon Morakot did offer a great opportunity to observe behaviors of bridge foundations under different types of hazards. The presented study is in an effort to characterize the performance of bridge foundations under extreme natural hazards so as to investigate possible causes of the failures. In this chapter, basic information and analysis of Morakot are introduced first. Secondly, typical types of bridge failures are summarized and genuine causes of failures are discussed as well. Last, research progress of an intelligent safety monitoring system for bridge foundation is illustrated to further characterize performance of bridge foundation under scouring and flooding conditions. The proposed system is developed in an effort to access the vibration and deformation characteristics of bridge structures under various natural hazards. The system is concluded to be capable of providing valuable information of bridge stability during critical events; as well as to have better durability, functionality and efficiency than the conventional scour monitoring systems.

The recent demand for performance-based seismic design of geotechnical structures requires knowledge about residual deformation of soils subjected to cyclic loading. This chapter concerns deformation characteristics of liquefied sand that may deform to a strain of 100% or more during and after strong ground shaking. To evaluate the liquefaction-induced ground deformation thus produced, it is essential to understand and validate the deformation characteristics of sand under very low effective stress. In this respect, a new type of triaxial shear test has been developed in which the effective stress is made extremely low by making the gravity effects very small. In other words, triaxial shear tests were conducted in a freefall capsule to achieve a state of null effective stress. It was shown that sand deforms in a viscous manner under constant load when effective stress has disappeared. The obtained coefficient of viscosity was then made use of to run deformation analyses on a geotechnical structures resting on liquefied sand.

Constitutive models developed in 1960s and 1970s by a group in Kyoto, with Shibata as the central figure, happen to have a theoretical framework mathematically similar to that of the Cam Clay models developed by the Cambridge Soil Mechanics Group in 1960s. The models developed in Kyoto were based on volume changes measured during constant stress ratio consolidation (q/p ^′-constant drained shear), and negative dilatancy (or contractancy) measured during p ^′-constant drained shear. The Cam Clay models were developed from assumptions of energy dissipation during shear. This chapter presents an interpretation of the physical meaning of dissipated energy and reveals the mathematical similarity between these two groups of constitutive models.