Modern Methods of Diaphragm Walls Design

This article addresses hazard reduction in deep excavations. The authors present a possible combination of prestressing of concrete structures (from bridge engineering) and prestressed structures of diaphragm walls from geotechnical engineering science. This innovative concept has not yet been shown in scientific articles. The “Sofistik” software (with TENDON module–SYSP/AXES/TOPP/TGEO) and its use is shown, with graphical presentations of the suggested solution. The authors compare the provided solution through usage of Sofistik and Plaxis software. The results show possible strengthening of sustainable construction by limitation of hazards and decreasing costs (via limitation of use of expensive steel reinforcement).

On Dam Failure Induced Seismic Signals Using Laboratory Tests and on Breach Morphology due to Overtopping by Modeling

Dam models were constructed in an indoor flume to test dam breach failure processes to study the seismic signals induced. A simple dam breach model was also proposed to estimate hydrographs for dam breach floods. The test results showed that when the retrogressive erosion due to seepage of the dam continues, it will eventually reach the crest at the upstream side of the dam, and then trigger overtopping and breaching. The seismic signals corresponding to the failure events during retrogressive erosion and overtopping of the dam models were evaluated. Characteristics of the seismic signals were analyzed by Hilbert–Huang transform. Based on the characteristics of the seismic signals, we found four types of mass movement during the retrogressive erosion process, i.e., the single, intermittent, and successive slides and fall. There were precursor seismic signals found caused by cracking immediately before the sliding events of the dam. Furthermore, the dam breach modeling results coincided well with the test results and the field observations. From the test and modeling results, we confirmed that the overtopping discharge and the lateral sliding masses of the dam are also among the important factors influencing the evolution of the breach. In addition, the widening rate of the breach decreases with decreased discharge. The proposed dam breach model can be a useful tool for dam breach warning and hazard reduction.

Assessment of Multiple Water-Related Hazards under Changing Climate in An Urbanized Sub-Region of Yom River Basin, Thailand

In the Chao Phraya River Basin, Thailand, water-related hazards, particularly river floods, flash floods and droughts, are increasingly causing damages to the local society, economy and environment due to changing climate and urbanization. As its impact, identification of key factors influencing the occurrence and severity of multiple water-related hazards at different temporal and spatial scales is therefore essential to further development of solutions for hazard reduction. The study identified through the analytic hierarchy process several key influence factors to water-related hazards, including precipitation, discharges, natural and green surface areas, and water storage, in the Upper Chao Phraya River basin, Thailand. These factors were then used for the assessments of individual and multiple hazards, as well as potential interventions for hazard reduction. A combination of several research methods was adopted for the hazard assessments, including simulation modelling, multi-criteria decision analysis, and spatial analysis based on both primary and secondary data sources. Eventually, spatial distribution of hazard levels at regional and local scales was mapped out to inform water-related multiple hazards and the potential of selected nature-based solutions to such hazards based on the data of specific years. It was found that increasing vegetation areas and having nature-based reservoirs can effectively improve water management in both wet and dry seasons, contributing to hazard reduction. It is expected that the assessments performed in this study can contribute to awareness-raising of water-related hazards and eventually enhance the preparedness of risk management in the studied areas.

Tectonic-Related Geochemical and Hydrological Anomalies in Italy during the Last Fifty Years

Seismic hazard reduction policies usually utilize earthquake catalogues and probability evaluations of occurrence. Further geophysical and geochemical parameters could contribute to hazard reduction policies as is currently the case in some countries, such as Iceland, Taiwan, China and Russian Federation. In the past four decades, intense research activity carried out by many different institutions in Italy has allowed us to recognize the most relevant sensitive sites for detecting acceleration in crustal deformation processes by means of geofluids monitoring. All scientific papers published in the period 1976–2020 concerning tectonic-related signals in geofluids have been considered. An in-depth review of previous and present-day research activities, as well as an update of two unpublished time series recorded in Central and southern Italy, has contributed to identifying areas where an instrumental array is still lacking and the most relevant priority areas for monitoring activities in geofluids. An atlas of all experimental sites utilized in recent decades has been obtained with the purpose of contributing to identifying the most suitable monitoring areas.

A VOXEL-BASED METHOD TO ESTIMATE NEAR-SURFACE AND ELEVATED FUEL FROM DENSE LIDAR POINT CLOUD FOR HAZARD REDUCTION BURNING

Drastic changes in the climate has revised the face of disaster management: it is contributing to abnormal intensity, frequency and duration of extreme weather and climate events. The year 2020 started with more than 100 fires burning across Australia. Hazard reduction burning has become a resolute and primary land management technique that contribute to the reduction of bushfire severity. One of the key variables to consider for this application is fuel load, as the accumulation of vegetation in a forest profile affects the intensity of the burn. Conventionally, fuel loads are measured by manually cutting the vegetation and physically measuring the quantity after dry heating. This process is expensive, and time consuming. There is an opportunity for these techniques to be digitised and automated to give results in a timely manner and work as a decision support tool for practitioners. This paper proposes a voxel-based approach that can be used for estimating fuel load and percentage cover of the vegetation, at the elevated and near-surface fuel/vegetation layer as a method to augment manual estimation. We use an airborne LiDAR pointcloud dataset of Vermont Place Park, Newcastle, Australia to test the method. The preliminary inspection of the results confirms the technique that can approximate conventional manual method. Next steps include performance testing including more dataset to derive quantitative measures on the approach.