The undulating topography of the Auckland urban region is susceptible to landslides of varying process-mechanisms, including: (1) earthflows of saturated Pleistocene Tauranga Group sediments, tephra and residual soils flowing off more competent underlying rock; (2) rotational slumping of man-made fill or Tauranga Group sediments; (3) block-slides of weak Miocene Waitemata Group sedimentary rock, dipping out of slope. Such landslides are often triggered by intense short periods, or prolonged periods of rainfall, such as the 'Tasman Tempest' and ex-Tropical Cyclone Debbie storms of 2017. Typically, rainfall infiltration results in a rise of the groundwater table and an increase of the pore water pressure, causing a reduction in effective normal stress and thereby soil strength, leading to landslides. Such landslide risk is likely to be accentuated in the Auckland region in future given the projected population growth and planned urban and commercial expansion driving the Auckland Unitary Plan (AUP). Indeed, the AUP encourages greater intensification by rezoning many areas to allow construction of low-rise apartments. Therefore, monitoring slope stability in the Auckland region is important, and requires assessment of the extent, rate of displacement, surface topography, and detection of tension cracks developing from slope deformation. Here, we present some investigations of slope failure mechanisms and activity in the Auckland region using Unmanned Aerial Vehicles (UAV) and structure-from-motion (SfM) photogrammetry. UAVs are emerging as an effective tool in landslide hazard management, allowing rapid collection of imagery and production of high resolution photomosaics from which safe evaluation of landslide deformation and activity can be undertaken. In addition, digital terrain models (DTMs) can be developed, and these can potentially allow time-series DTM-differencing and/or comparison with LiDAR data in order to evaluate landslide activity. UAV-derived topographic data is also useful for 2D/3D slope profile construction which is important for accurate parameterization of numerical slope stability models. Thus, the UAV-SfM technique represents an effective, rapid, financially viable alternative to traditional topographic surveying and LiDAR.

Many grabens − approximately 50 m wide, several hundred meters long, and 1.5 m deep − formed in the caldera of the Aso Volcano during the 2016 Kumamoto Earthquake. Following the subsidence of the ground surface, the houses in the grabens sank without significant damage; there was no damage to the glass windows. After the earthquake, the authors conducted thorough on-site investigation to determine the mechanism of the grabens and to propose an appropriate method to restore the affected ground to a usable state. First, the distribution of the ground surface displacement was measured by laser scanning from satellites. This measurement revealed horizontal displacements of approximately 2 m to 3 m at, and around, the grabens. A surface wave survey clarified that the shallow soil layers under the grabens were looser than the soil layers surrounding the grabens. Therefore, it was estimated that the grabens were formed by the horizontal extension force from local large displacements. Deep borings also showed that a thick clayey layer was deposited from GL-17 m to GL-50 m in the zones where large horizontal displacements occurred. The bottom of this clayey layer was inclined because volcanic ash had deposited in a large lake several thousand years ago.

We often misinterpret ground conditions in various stages of a construction project, such as planning, investigations, design, and construction stages. The misinterpretation occurs because the ground conditions are usually uncertain to various degrees even after geotechnical site investigations. The paper first discusses the occurrence of the misinterpretation, which (1) largely depends on the volume of quality data and human skill, and (2) generally happens while making geological models, geotechnical models, and civil/structural designs. Secondly considered is the uncertainty of the ground conditions, the awareness of which varies depending on people who handle the geo-information. Thirdly, among many misinterpretations we make, only a few cases result in failures, because of some traditional safeguards. However, due to changing practices of geotechnical designs and construction contracting recently, the conventional safeguards are not as secure as before against the failures caused by the misinterpretation of the ground conditions. Lastly, discussed are possible ways to reduce misinterpretation. Keys could be awareness of the uncertainty of the ground conditions and improvement of communications throughout the construction projects by all stakeholders. Geotechnical societies are well suited to contribute to this area, and project owners and managers have great power to prevent failures cause by the misinterpretation of the ground conditions.

Geographically remote, small rural towns typically rely on multiple critical infrastructure networks with limited redundancies to support key services. Additionally, facilities that people take for granted in larger population centres, such as supermarkets and schools, are more widely distributed in low population density regions. We adopt the 14 November 2016 (Kaikōura) earthquake in New Zealand as a case study to explore critical infrastructure challenges and impacts, service disruptions, and community adaptations in four small North Canterbury and Marlborough towns – Waiau, Culverden, Seddon and Ward. However, behavioural, infrastructure and legislative adaptations can be inherent or quick to evolve in small towns with frequent service disruptions. Despite these factors, small towns are often underrepresented in impact assessments and appear to have been a low priority for investigation in the past. For the purposes of this paper we focus on the small rural town of Waiau in North Canterbury. Existing records of impacts and adaptations were combined with seismic and co-seismic hazards and emergency management activities to produce a preliminary geospatial timeline of events following the Kaikōura earthquake. Overlaying critical infrastructure with known and simulated co-seismic hazards enables us to conceptualise areas of high hazard exposure; an important component of risk. Along with the results of our discussions with community and industry members, this information can be fed into future research to inform resilience-building efforts. In this paper we present the latest findings and suggest future applications for Geospatial Information Systems in reducing disaster risk in small towns.

Serious disaster took place in Mashiki Town of Kumamoto Prefecture, Japan by the 2016 Kumamoto Earthquakes. The authors carried out boring investigation together with undisturbed sampling of soils at the two different sites. One is located in the area where there is almost no damage, and another is in the seriously destructed area. In the present paper, a series of one-dimensional seismic assessments in terms of the total stress numerical analysis is conducted for the above-mentioned two locations. The calculated performance shows that the response acceleration at the ground surface at the seriously damaged site reaches 1200gal due to amplification in the sand/clay alternating strata near the surface while the maximum acceleration at the base exhibits 250gal with the predominant period of 0.9s. On the other hand, remarkable attenuation is found to occur in the middle of the thick soft clay layer at the no damaged site, which results in the relatively smaller response acceleration, 700gal at the ground surface. The difference in this ground vibration between both sites is investigated by comparing the transfer functions calculated for the individual sites. Then, it is found that the mode of ground vibration is strongly dependent upon the interactive relation between the characteristics of the earthquake wave and the subsoil condition.

Although Auckland is one of the country's least seismically active regions, the earthquake hazard in the region cannot be disregarded given the potential social and economic impacts. As part of this, a good understanding of the co-seismic hazards across the region is of key importance. This paper presents on the methodology adopted for the GIS-based microzonation for liquefaction hazard across the Auckland region and the updated liquefaction-induced ground damage maps based on the recently developed MBIE guidance. Geology-based screening is initially applied across the region to identify areas where liquefaction is unlikely, with a separate categorisation for alluvial deposits with volcanic content in this region. The remaining areas are classified as “liquefaction damage is possible”, a broad classification that can only be refined where additional data is available. Borehole-based investigation data and elevation details are used to further screen out areas where non-liquefiable deposits are present. Where CPT soundings and groundwater data are available, detailed liquefaction assessments are carried out that enable refinement of classification beyond the high-level geology-based screening. LSN values for 100- and 500-year return period ground motions are used to classify areas where similar geotechnical conditions are present with liquefaction vulnerabilities ranging from very low to high. With these multiple approaches, regional liquefaction-induced ground damage maps are developed for Auckland region for different levels of investigation detail.

The geotechnical engineering industry has taken an interest in three dimensional (3D) ground modeling more than before owing to recent prevailing of Construction /Civil Information Modeling (CIM). However, it is said that 3D ground model development, even only creation of 3D geological framework model of subsurface, takes still considerable time and cost due to special technique which requires qualified experts and geological knowledge. Therefore, it is important for practical geotechnical design engineers to find the way to create 3D models efficiently. The authors tried to develop 3D ground model of which dimension is approximately 2.8km x 1.8km with widely spaced borehole logs for conducting earthquake response analysis. We used 3D ground modeling system of ‘ Geomap3D’ (Toyoda and Nishikaichi, 2005) which has been developed as simple ground modeling system. In this report, the outline of developing 3D geological subsurface model is explained as an example of site specific study. Property values of each engineering unit are summarized as well based on literal values. It was found that 3D model could efficiently be developed by using this system in spite of limited number of borehole logs.

Because of water drainage, liquefied sand becomes denser after liquefaction. Therefore, such sand is not expected to liquefy again. However, repeated ground liquefaction has been reported from several earthquake events. We have considered some reasons for frequent reliquefaction: (1) the upper ground remains in a loose condition after liquefaction and (2) increased pore water pressure remains during subsequent earthquake events. This study investigated reliquefaction mechanisms using triaxial tests with bender elements (BE) and local small strain measurements (LSS) to explore other reasons for reliquefaction. The experimentally obtained results demonstrate that initial shear modulus G0 is insensitive to specimens with shear and liquefaction histories, although the liquefaction strength varies considerably according to the stress and liquefaction histories. The LSS test results indicate that the elastic strain region of sand shrinks according to the liquefaction history while maintaining almost unchanged G0. Furthermore, the sand particle orientation was evaluated from 2D images obtained using optical digital microscopy.

Liquefaction hazard maps are a useful resource to help estimate the exposure and potential liquefaction-induced damage to the built environment. The most robust approach for the development of these maps is through the use of in-situ investigation data and simplified liquefaction evaluation procedures. When infrastructure networks are the focus of assessment, this method can be expensive and labour-intensive due to the large geospatial extent of these networks and the large number of investigation data required to provide good coverage. In these cases, geospatial methods can be used as an alternative approach. This paper focusses on the assessment of the exposure of New Zealand’s transportation (rail, state highways, and bridges) and power transmission networks to liquefaction, using geospatial liquefaction susceptibility methods. This approach has enabled the initial quantification of national exposure across each network for different liquefaction susceptibility categories, demonstrating that transportation systems are situated in areas that are more susceptible to liquefaction compared to power transmission facilities. To identify areas of high risk in terms of liquefaction induced damage, susceptibility needs to be linked with the seismic hazard across the country; this is the focus of the next step of this research. The criticality or significance of infrastructure should also be considered as part of this process to better quantify the impact of damage to the wider economy and society. This includes the modelling of other infrastructure networks, such as local roads, and the analysis of links between networks and areas of interest, such as populated places and sea ports.

In land scarce Singapore, the need for underground space development and usage has increased significantly in recent years due to more infrastructures built underground to accommodate the growing urbanisation. This leads to more competing usage and conflicts in the underground spaces. Failures that occurred in the past underground construction are associated with the lack of understanding of the underlying ground conditions and associated risks. Therefore, it is important to understand the subsurface conditions before carrying out underground space development works. In view of this, geological survey and investigation works were carried out in several parts of Singapore to study and investigate its geology, and also to identify suitable sites for underground space development. The geological survey works carried out include drilling of 170 deep boreholes and 155 km of seismic survey. These data were used to develop the Singapore-wide 3D geological model, which is able to provide a 3D visualisation of the geology of Singapore. The geological model is developed using the 3D earth modelling software GOCAD Mining Suite. In order to explore feasible area for developments of rock cavern, a 3D geotechnical hazard map has also been prepared based on lithology, rock mass quality, and distances from faults and folds. The current work proved that 3D geological model, in spite of its limitations, is very useful for interpreting and establishing the general lithostratigraphy and structure of Singapore’s geology.

Applications of the BIM (Building Information Modeling) to civil engineering and construction industries have been started in Japan, under the initiative of Ministry of Land, Infrastructure and Transport of Japan. In the BIM for infrastructure, geological/geotechnical investigation results are transformed into a 3-D model and are consistently managed as public project information throughout the entire life cycle of an infrastructure to be shared and used among relevant parties. However, it should be noted that geological/geotechnical model is an inferred model with uncertainty, unlike product model for building structure that expresses a visible object based on a design drawing. In order to reduce such risks of improper designing that the accuracy of geological/geotechnical model is overestimated or misused in the downstream operations, it is important to maintain the records that specify the uncertainty of inferred model along with underlying actual data. We, members of a working group under the ISSMGE ATC10, are working on the following two issues currently; 1) identification of the factors that affect model uncertainty and 2) review of Japanese and international standards on the 3-D modeling. In first issue, based on some examples of construction projects, the factors that affect the model uncertainty and the information to be maintained for downstream processes have been identified. For example, modeling area and the validity for its setting, modeling process, type and position of input data, geologic stratigraphy applied to the model, and rationale for stratigraphic identification are recognized as such factors. In the standard review, a total of 51 Japanese and international standards related to geological/geotechnical survey have been reviewed and we recognize that there are descriptions of requirements for the reliability of the 3-D model. Some terms such as 'geological model' and 'geotechnical model' are found to have been used in different meanings and causes confusions among stakeholders, so we are defining and categorizing some important terms such as geological model, geotechnical model, geotechnical information, uncertainty and reliability. We continue to examine the actual description methods and formats that allow the information related to uncertainty is handed over to the downstream processes so that the uncertainty can be re-evaluated afterward. We plan to include the final outcomes of this study in "JAPANESE GEOTECHNICAL SOCIETY STANDARDS: Geotechnical and Geo-environmental Investigation Methods”.

Pumice materials are frequently encountered in many engineering projects in the central part of the North Island, New Zealand. Because of their lightweight, highly crushable and compressible nature, existing empirical correlations developed for hard-grained (quartz) sands are not applicable, and therefore they are problematic from an engineering and construction viewpoint. With engineering developments currently on-going in the region, a better understanding of the characteristics and locations of these pumiceous layers has become necessary. This paper attempts to identify the field characteristics of pumice deposits based on conventional geotechnical methods for the purpose of mapping the locations of pumiceous layers across the Bay of Plenty and Waikato regions. For this purpose, existing geotechnical data within the target regions, including standard penetration tests (SPT), cone penetration tests (CPT), seismic dilatometers (sDMT), machine boreholes and associated laboratory testing, were compiled. In addition, pumice deposits were identified within the existing data as well as the extent of the stratigraphic unit(s) and typical trends within the data set and correlations across various test types were analysed. It is envisioned that the outputs presented in the paper will be beneficial to researchers, practicing geotechnical engineers, roading authorities and council planners in terms of providing better engineering understanding of these problematic soils.

Hill slope landslide and erosion were happening at the USM hostel due to heavy rainfall and stormy weather duringthe month of November till December 2017. This was a monsoon season, however this occurrences was not normal and in Penang alone there where so many slope failure and flash floods. A remedial work was carry out to correct the slope failure on site, where during the seasonal rainfalls the slope was heavily eroded and all the trees and grouted slope which was in placed before failed to sustained from the water movement. The site was then explored to foresee the major problems and to counter the stability by carrying out 2D Soil Resistivity and site investigation to understand, analyze and rectify the problem. From this study, we have conducted the soil mapping of the ground to further understand the soil condition so that all the correct measures can be done effectively. Since, this needs to be rectified immediately; therefore soil nailing and grouting method were proposed along with different counter measure to stabilize the slope. This was done under three weeks and monitoring systems was included to measureground water level and inclination of ground movement. From the study it shows that after rectification and placing the right infrastructure to the slope, the system in place are now stabilized and able to cater heavy downpour aftercompletion.

The actual problem for today is the introduction of geoinformation database in the management of urban planning. Development geoinformation database and using it in various civil engineering projects largely depends on the accuracy of available borehole information as well as borehole distribution density. The database development has focused in urban areas because of their social and economical importance. Geotechnical database plays a significant role to investigate the regional subsoil conditions prior to detailed investigation. The regional geotechnical characteristics can easily be grasped by the distribution of those soil properties. The Geo-database can provide sufficient and helpful information. This paper introduces the geoinformation database for Astana, but for the others areas efforts are underway. More than 2000 borehole data were collected. Basically, the information including soil classification, gradation, location, depth and coordinates of boreholes, NSPT and NDPT values, and groundwater levels has been entered in the geo-database. By using the geo-database, cross-sections of an area can be easily drawn over the computer screen, and soil parameters such as soil classification, gradation, the thickness of each ground stratum, map of zoning at optimization of length of driving and boring piles, groundwater level, NSPT values, etc. can also be readily known. The use was also made of the developed geo-database for assessing of the construction site and decrease expenses for carrying out surveys and design work. The given program, includes for today data of 2000 boreholes, 402 points of static penetration and 125 points of dynamic penetration which has allowed to analyse regional conditions of soils before detailed research.