Analysis of Vertical Earth Pressure Acting on Box Culverts through Centrifuge Model Test

Due to the lack of surface space, most structures are heading underground. The box culvert is underground infrastructure and serves to protect the buried structure from the underground environments, but it has a different characteristic from other structures in that the inner space is empty. Therefore, in this study, the vertical earth pressure which is the most significant effective stress acting on a box culvert was measured by conducting a geotechnical centrifuge model test. A box culvert was installed following the embankment installation method, and the vertical earth pressure acting on it was measured considering the cover depth, gravitational acceleration, and loading and unloading conditions. The soil pressure measured was greater than the existing theoretical value under high cover depth and the unloading condition, which is considered as the variability of many soils or the residual stress acting under the loading condition. Finally, a goodness-of-fit test was conducted as a part of variability analysis. The measured earth pressure was found to be considerably larger than the existing theoretical value, and the variability was large as well. This means the existing theoretical equation is under-designed, which should be reflected in future designs.

Visible Corrosion Damage in Carbonated Reinforced Concrete

This study discusses visible corrosion damage due to carbonation in concrete balconies and facades. The focus of the study was to find out how the age of the structure, cover depth of concrete, carbonation coefficient, capillarity of concrete and the climate affect visible corrosion damage. The research data consist of condition investigation reports of existing concrete balconies and facades built between 1948 and 1996. Balcony slabs and brushed painted facades were the most prone to visible corrosion damage. None of the researched panels met the required minimum cover depth of reinforcement even at the time of construction. However, most of the visible damage on the database was localized damage and there was not much visible corrosion damage. The carbonation coefficient of balconies was higher than the carbonation coefficient of facades. Brushed painted facade panels had clearly higher carbonation coefficient than other facade panels. The carbonation coefficient was considerably lower on white concrete panels compared to other panel types. When capillarity of concrete raises, the carbonation rate of concrete increases slightly. However, no correlation can be seen. The capillarity of concrete and the carbonation rate of concrete had a major range.

Chemical and algological composition of the snow cover at the mouth of the Onega river (White Sea basin)

In the study, the content and speciation of Mn, Pb, Cd, Zn, Cr, Ni, Co, Cu, and Fe in the snow cover at the mouth of the Onega river (White Sea basin) at the end of the winter periods in 2018, 2019 and 2020 were determined. Winter 2019 year was the snowiest, as the maximum values of the snow cover depth and water equivalent were almost two times higher than in all other years. The total content of suspended matter in the snow cover was 0.2–5.5 μg/L. Increased concentrations of suspended solids were identified near highways. Mn, Cr and Ni were present in the snow cover mainly in their dissolved form, while Fe, Pb and Co were mostly contained as solids. The algological composition of the snow cover was also studied.

Safety Performance Enhancement Scheme for Munition Storages by applying the Concept of Shallow Underground Configurations

Practical demand for the expansion of military ammunition and explosives storage in both volume and number has been increased, but due to the regulations applying on safety distance that require those facilities to be isolated from a civilian presence there are constant complications that arise. Recent incidents include petitions to either alleviate said regulations or relocate several ammunition storage facilities neighboring civilian areas are further development. Two types of underground ammunition storage facilities wold be considered in practice; the first is the tunnel-type which is applicable to areas that have sufficient depth of the cover and the latter is the sub-surface type that retains a sufficient depth of soli layer which can especially be utilized in areas that do not meet clearance requirements nor have geographical limitations. For the sub-surface type storage, there are two construction schemes for construction to meet safety-distance requirements. The existing popular ECMs (Earth Covered Magazines) have shallow soil cover for just plantation camouflage that is not affect the pressure suppression effect due to the internal explosion. Therefore, the scheme of the increasing soil cover depth to some amount, if applicable, pressure and fragment suppression can be achieved. The open-cut method for new construction is easily applied for this purpose in the field. This study addresses the safety distance reduction effect by increasing the soil cover depth on the ECM type storage facility by applying theoretical and numerical analysis.

The Cover Depth Effect on Corrosion-Induced Deterioration of Reinforced Concrete Focusing on Water Penetration: Field Survey and Laboratory Study

Reinforced concrete bridges were visually surveyed in Japan, Thailand, and Vietnam to study the deterioration caused by internal steel corrosion under different climates, focusing on the concrete cover depth. Spalling or cracking arising from corrosion is likely where water is supplied. According to prior studies and our surveys, a concrete cover depth of more than 40 mm was found to prevent spalling, regardless of environmental conditions and structure age. Because water supply at steel is a key corrosion factor, it was hypothesised that under natural conditions, the water penetration in concrete would remain at a depth of approximately 40 mm. Our laboratory study examined water penetration under drying and wetting conditions. The results also suggested that under periodic rainfall conditions, the threshold of water penetration was not exceeded. The numerical study indicated maximum moisture evaporation to facilitate oxygen diffusion occurred at a depth of approximately 30–40 mm unless the concrete was exposed to continuous drying for more than one month. It was experimentally and numerically concluded that an adequate cover depth of greater than 40 mm could inhibit moisture and oxygen penetration at the steel, which supported the survey findings of cover depth effect on a high resistance to corrosion-induced deterioration despite an increase in service life.