Seismic Rotational Displacements of Gravity Quay Walls Considering Excess Pore Pressure in Backfill Soils

The effect of excess pore pressure developed in backfill soil during earthquake is an important consideration in rotational displacement prediction of gravity quay walls. Based on Newmark’s sliding block concept and stress-based excess pore pressure model, a new method is proposed to predict the critical rotational acceleration and angular acceleration time histories considering the development process of excess pore pressure in earthquake events. Then, the rotational displacement of gravity quay walls is predicted according to the calculated angular acceleration time histories. By using the proposed method, the effects of various parameters involved in the calculation have been studied by carrying out a parameter study. Analysis results reveal that the influence of excess pore pressure on the rotational displacement of gravity quay walls with saturated backfill soil is significant, so, can not be ignored; and rotational displacement is sensitive to the magnitude of earthquake, horizontal and vertical seismic accelerations of ground motion, wall and soil friction angle, and soil relative density. When the rotation and sliding of wall occur simultaneously, rotation and sliding will be inhibited by each other.     

Variety in cereal cultivation in the Late Bronze and Early Iron Ages in relation to environmental conditions

The objective of this paper is to assess the relationship between the cereals cultivated in the Late Bronze and Early Iron Ages (ca. 1250–400 BC) within the area of the present-day Czech Republic, and their environmental settings. The various charred caryopses of cereal species represented in the archaeobotanical assemblages from 35 archaeological sites differ, especially in the proportion of wheat and barley. The cereal assemblages were compared regarding site altitude, weather conditions, soils and soil productivity. The most important environmental variable influencing the choice of a particular crop seemed to be altitude which is correlated with other variables such as the length of growing season, mean annual temperature, soil quality etc. Although the ecological requirements of cereals cultivated in the Late Bronze and Early Iron Ages are not known, they presumably thrived under similar conditions to present-day species/varieties, and the strategy of past crop husbandry was based on similar principles as today, e.g. flexible adaptation to local environmental conditions, in an effort to achieve optimal yields and reduce the danger of crop failure.     

Isotopically distinct modern carbonates in abandoned livestock corrals in northern Kenya

We report δ¹⁸O and δ¹³C data from modern carbonate in soils and dung samples from 3 recently abandoned livestock corrals in northern Kenya. Calcium carbonate content is higher within ∼5 cm depth that contains a mixture of dung and surface soils of corrals than in soils below 5 cm depth. We radiocarbon dated carbonates from 0.5 to 40 cm depths in two corrals and one control site. Surface carbonates (0.5 cm) from the two corrals were formed from modern carbon (>1955) when the corrals were active, while all other carbon is >16,000 years (BP) old. Shallow carbonate is also enriched in ¹⁸O (δ¹⁸O up to 3.0‰) and depleted in ¹³C (δ¹³C up to −12.0‰) with respect to carbonate at deeper levels and at two control sites. The δ¹⁸O and δ¹³C of soil carbonates (δ¹⁸O_SC and δ¹³C_SC respectively) in corrals are inversely correlated for depths up to about 15 cm where organic carbon is greater than 0.5%. Below that depth, there is a positive correlation between δ¹⁸O_SC and δ¹³C_SC values, similar to that observed in a control site.     

Shear Modulus and Damping Ratio of Cohesive Soils

This article presents results from a laboratory investigation into the dynamic characteristics of reconstituted and undisturbed cohesive soils by means of resonant-column tests. In particular, results showing the influence of various soil parameters, such as confining stress, overconsolidation ratio, void ratio, plasticity index, calcium carbonate content, and time of confinement on shear modulus and damping ratio at small and high shear strains are presented and then discussed. Relationships for the small-strain shear modulus, the degradation of shear modulus at high strains, and the increase of damping ratio at high strains over its small-strain value are proposed. Finally, the practical implications of the results in the context of seismic site response analysis are discussed.     

Rocking of Non-symmetric Rigid Blocks in Buildings Considering Effects Associated with Dynamic Soil-Structure Interaction

A dynamic model for the estimation of the rocking and/or overturning response of a free-standing non-symmetric rigid block considering rotational and horizontal excitation is proposed. The block is situated at different levels of a building with flexible base subjected to earthquakes. Base flexibility introduces the rotational component of the excitation due to dynamic soil-structure interaction (DSSI). The model is used to assess the influence of the dynamic soil-structure interaction on the behavior of the block. An illustrative example of the proposed model for non-symmetric rigid blocks in 5-, 10-, and 15-story buildings located in soft soils considering earthquakes from different seismic sources is presented. Results show that it is important to consider kinematic effects as well as inertial effects of DSSI in the dynamic response of contents. The influence of base flexibility depends on the change of spectral intensities associated to the increase of the building structural period and is larger for higher building levels.     

The widespread occurrence of Celtic field systems in the central part of the Netherlands

The detailed elevation model based on airborne laser altimetry (AHN) proved to be a reliable tool to detect well-developed Celtic field systems, characteristic arable plots of the Iron Age. They were detected in the central part of the Netherlands, where only a limited number of Celtic field systems have been recognized in the past. Most of these previously detected systems were identified in the northern part of the Netherlands or in the southern part, but not in this zone. About 1200 ha of well-developed systems could be identified by AHN in the central part of the Netherlands, of which only 136 ha were registered as an archaeological monument. Another 335 ha of archaeologically identified Celtic field systems were not accepted or recognized by AHN, because they were morphologically less well-developed. Most of the around 1050 ha new discoveries occur in rough vegetations and forested areas, and can hardly be identified with previously used geodetic methods and aerial photography. Less well-developed or preserved systems were even more extensive and remnants were traced as fossil arable layers below plaggen soils or on lower slopes incorporated in mediaeval reclamations. The newly identified Celtic field systems, therefore, can be considered as remnants of much larger areas once covered with these arable plots. In the central part of the Netherlands, the estimated area once covered was at least around 4500 ha, more than enough to supply 10,000 people with cereals. Well-developed Celtic field systems started to develop in the late Iron Age with formation intensifying during the early Roman Period. The central part of the Netherlands is situated just north of the river Rhine, the former boundary of the Roman Empire, the Limes. The newly discovered extent of Celtic field systems will have influenced the interaction between different cultures on the border of the Roman Empire in the early Roman Period, about which very little is known. This perspective underscores the need for an integrated conservation policy and in-depth research through excavations in the near future.