Search

For archaeology to survive in the present and for critical discourse on the past to thrive, archaeologists must advocate for the discipline's continued relevancy. In this Debate article, the authors illustrate the potential and challenges of such advocacy by examining contemporary perceptions of the Roman period Hadrian's Wall and how it relates to modern border landscapes--namely the US/Mexico border. They argue that archaeologists have not addressed the imagined continuity of socio-political narratives surrounding borderlands, calling for wider recognition of border materiality. The authors contend that the uncritical portrayal of the past, particularly in politically charged spaces such as border zones, can contribute to inequality and oppression in the present. Keywords: border studies, borderlands, Roman frontiers, political action, contemporary archaeology, landscape archaeology, Introduction The physical demarcation of borders may have lasting effects on a landscape. Border walls may leave physical traces and affect social relationships and practices long after those walls cease [...]

Archaeologists should always have their say in the interpretation of the archaeological record. Moreover, they should not allow those interpretations to be misappropriated by others, whether politicians, journalists or specialists [...]

Hanscam and Buchanan (2023) give us an insightful comparative analysis of Hadrian's Wall and the US/Mexico border wall. Their analysis shows how critically to study and use these long walls [...]

The wider case presented by Hanscam and Buchanan (2023), as I understand it, is for archaeologists to consider directly the relation of the past in shaping social and political narratives [...]

This paper describes the efforts made in rectifying a large prestressed, L-shaped, vertical reaction wall with circular cavities and the lessons learnt. The wall was to be constructed with a certain flatness requirement, which it later turned out was not met. Though various studies have been undertaken in the past describing rectification of horizontal concrete floors, the present study discusses a novel approach to determine the extent of non-compliance and then re-surfacing of the vertical wall to achieve required flatness. The paper discusses in detail the applicability of various instruments like profilometers, water level manometers, and laser-based tools in determining the extent of undulations. It was found that the rotating laser-based tool best served the purpose for defect identification and that placing a layer of micro concrete along with a bonding agent using a novel construction method helped to achieve the desired level of flatness. Key words: RC wall, flatness, undulation, rotating lasers, micro concrete, resurfacing. Cet article decrit les efforts deployes pour rectifier un grand mur de reaction vertical de precontraint en forme de L avec des cavites circulaires ainsi que les lecons apprises. Le mur devait etre construit avec une certaine exigence de planeite, qu'il s'est avere plus tard n'a pas ete respectee. Bien que diverses etudes aient ete entreprises dans le passe pour decrire la rectification de planchers de beton horizontaux, la presente etude examine une nouvelle approche pour determiner le niveau de non-conformite, puis le resurfacage du mur vertical afin d'obtenir la planeite requise. Le document examine en detail l'applicabilite de divers instruments comme les profilometres, les manometres de niveau d'eau et les outils a laser pour determiner l'etendue des ondulations. On a constate que l'outil a laser rotatif servait le mieux a l'identification des defaillances, et que le placement d'une couche de micro-beton avec un agent de collage utilisant une nouvelle methode de construction a aide a atteindre le niveau de planeite souhaite. Mots-cles : mur en beton arme, planeite, ondulation, lasers rotatifs, micro-beton, resurfacage., Introduction During the construction of structures, it should be ensured that the requirements and specifications, which could be in terms of strength or aesthetics or any other functional requirements, are [...]

The performance of a capillary barrier cover as a cover system is affected by the ability of the capillary barrier to store water. To increase the water storage of a capillary barrier cover, the dual capillary barrier (DCB) concept is proposed. The objective of this paper is to investigate the water storage of the proposed DCB as compared to the storage of a traditional single capillary barrier (SCB). The investigation is conducted using two one-dimensional infiltration column tests under different rainfall conditions. The results show that a DCB stores more water as compared to SCB. The results show that the fine- grained layers of a DCB have higher volumetric water contents during drainage as compared to that of the fine-grained layer of an SCB. The higher volumetric water content is caused by the fact that the thickness of the layers in a DCB corresponds to a pore-water pressure head range where the material has the highest volumetric water content. In addition, a slower drainage rate is resulted from additional layering in a DCB. Key words: water storage, dual capillary barrier, infiltration column, volumetric water content, recycled asphalt. La performance d'une couverture a effets de barriere capillaire en tant que systeme de recouvrement est affectee par la capacite de la barriere capillaire a stocker l'eau. Afin d'augmenter le stockage d'eau dans une couverture a effets de barriere capillaire, le concept de double barriere capillaire (DCEBC) est propose. L'objectif de cet article est d'etudier le stockage de l'eau dans la DCEBC proposee en comparaison avec le stockage d'une simple barriere capillaire (CEBC) traditionnelle. Les investigations sont realisees a l'aide de deux essais en colonne d'infiltration unidimensionelle soumis a differentes conditions de precipitations. Les resultats demontrent que la DCEBC stocke plus d'eau comparativement a la CEBC. Les resultats montrent que les couches fines de la DCEBC ont des teneurs en eau volumiques plus elevees durant le drainage par rapport a la couche fine de la CEBC. La teneur en eau volumique plus elevee est causee par le fait que l'epaisseur des couches dans la DCEBC correspond a l'etendue des pressions interstitielles oU le materiel a la teneur en eau volumique la plus elevee. De plus, un taux de drainage plus faible est obtenu avec l'ajout d'une couche dans la DCEBC. [Traduit par la Redaction] Mots-cles: stockage d'eau, double barriere capillaire, colonne d'infiltration, teneur en eau volumique, asphalte recycle., Introduction A capillary barrier is an alternative cover system for waste disposal. Capillary barriers have been used for landfill covers in dry climates due to their simplicity (Johnson et al. [...]

The current state of practice for the seismic design of basement walls in Vancouver is based on the Mononobe-Okabe (M-O) method using a peak ground acceleration (PGA) of 0.46g mandated by the National Building Code of Canada (NBCC). A series of dynamic numerical analyses are conducted to study the seismic performance of basement walls designed for the M-O earth pressures derived from different fractions of the current building code mandated PGA. The walls are subjected to seven ground motions spectrally matched to the uniform hazard spectrum (UHS) prescribed by the NBCC for Vancouver. The analyses show that current engineering practice for designing basement walls based on the M-O method and using a PGA of 0.46g is too conservative. The analyses suggest that a wall designed using a 50%-60% PGA will give an acceptable performance in terms of drift ratio. The results of sensitivity analyses on input parameters are also presented and discussed. Key words: seismic design, basement wall, state of practice, dynamic analysis. L'etat de la pratique actuelle dans la conception sismique de murs de sous-sols a Vancouver est basee sur la methode Mononobe-Okabe (M-O) et avec une acceleration du sol au pic (ASP) = 0,46g, tel que mandate par le Code National du Batiment du Canada (CNBA). Une serie d'analyses numeriques dynamiques sont realisees pour etudier la performance sismique de murs de sous-sols congus pour les pressions des terres selon la methode M-O obtenues pour differentes fractions de l'ASP mandate par le code du batiment actuel. Les murs sont soumis a sept mouvements de sol ayant un spectre identique au spectrum de danger uniforme (SDU)prescritparle CNBA pour Vancouver. Les analyses demontrent que la pratique actuelle d'ingenierie pour la conception de murs de sous-sols basee sur la methode M-O et qui utilise l'ASP de 0,46g est trop conservatrice. Les analyses suggerent qu'un mur congu avec 50 a 60 % de l'ASP aura une performance acceptable en termes de coefficient de derive. Les resultats des analyses de sensibilite realisees sur les parametres d'entree sont aussi presentes et discutes. [Traduit par la Redaction] Mots-cles: conception sismique, mur de sous-sol, etat de la pratique, analyse dynamique., Introduction The seismic response of basement walls is a complex soil structure interaction problem that depends on many different factors, such as the nature of the input motion, the dynamic [...]

Existing soil nailing design methodologies are essentially based on limit equilibrium principles that together with a lumped factor of safety or a set of partial factors on the material parameters and loads account for uncertainties in design input parameter values. Recent trends in the development of design procedures for earth retaining structures are towards load and resistance factor design (LRFD). In the present study, a methodology for the use of LRFD in the context of soilnail walls is proposed and a procedure to determine reliability-based load and resistance factors is illustrated for important strength limit states with reference to a 10 m high soil-nail wall. The need for separate partial factors for each limit state is highlighted, and the proposed factors are compared with those existing in the literature. Key words: soil-nail walls, limit states, reliability, load and resistance factor design. Les methodes existantes de conception de clous de sol sont basees essentiellement sur les principes de l'equilibre limite qui, combinees avec un facteur de securite regroupe ou un ensemble de facteurs partiels sur les proprietes des materiaux et les charges, tiennent compte des incertitudes dans les valeurs des parametres de conception entres dans le modele. Les tendances recentes dans le developpement de procedures de conception de structures de retention se concentrent sur la conception par facteur de charge et resistance (CFCR). Dans cette etude, une methodologie pour l'utilisation de CFCR dans le contexte des murs de clous de sol est proposee, et une procedure pour determiner les facteurs de charge et de resistance selon la fiabilite est illustree pour des etats limites de resistance importants, en reference a un mur de clous de sol de 10 m de haut. Le besoin d' etablir des facteurs partiels separes pour chaque etat limite est souligne, et les facteurs proposes sont compares a ceux disponibles dans la litterature. Mots-cles : murs de clous de sol, etats limites, fiabilite, conception par facteur de charge et resistance. [Traduit par la Redaction], Introduction Design methodologies for soil nailing are based mainly on the limit state design principle. Soil nailing design codes-recommendations commonly used in European countries, such as Clouterre (1991), Highway Agency [...]

An instrumented geogrid-reinforced wall constructed on a highly compressible foundation was deconstructed 16 months after its completion, providing a unique opportunity to exhume and examine the instrumented geogrids that were used to construct the wall. The objectives of this post mortem study were: (1) to inspect the condition of the strain gauges that were attached to the geogrid layers before construction and to verify the reliability of their output; (2) to develop a procedure in which the residual (plastic) strains along exhumed geogrid panels could be determined; and (3) to assess the in situ strain and force distribution along geogrid panels based on the measured residual strains from the exhumed geogrids. After exhumation, it was observed that many of the attached strain gauges failed due to full or partial debonding from the geogrid, thus rendering outputs which potentially underestimated the actual strain. Combining aperture measurements of virgin and exhumed geogrids, all from the same manufacturing lots, enabled the assessment of residual strains following stress relaxation. Laboratory simulation of loading and unloading, including creep and relaxation, yielded a relationship between the measured residual strains and the in situ strain and force distribution; i.e., the residual strain fingerprint provided insight into the behavior of the geogrids within the wall prior to its deconstruction. The mobilized maximum tensile strains in the geogrid panels along the height of the wall were roughly uniform, in the range 4 [+ or -] 1%. These findings imply that if the same type of reinforcement had been used throughout the height of the wall, the mobilized force along the height would have been relatively uniform. The back- calculated maximum force in the geogrids indicated that the factor of safety on the long-term strengths of the geogrids ranged from about 1.4 on the stronger/stiffer geogrid to about 1.8 on the weaker/softer geogrid. DOI: 10.1061/(ASCE)GT.1943-5606.0000354 CE Database subject headings: Creep; Geogrids; Retaining walls; Strain gages; Stress; Reinforcement. Author keywords: Creep; Geogrid; Reinforced wall; Strain gauge; Stress relaxation.

Hybrid coupled walls (HCWs) are comprised of two or more reinforced concrete wall piers connected with steel coupling beams distributed over the height of the structure. Extensive research over the past several decades suggests that such systems are particularly well suited for use in regions of moderate to high seismic risk. This paper reviews the state of the art in seismic modeling, analysis, and design of HCW systems. Design methodologies are presented in both prescriptive and performance-based design formats and a discussion of alterative types of hybrid wall systems is provided. DOI: 10.1061/(ASCE)ST.1943-541X.0000186 CE Database subject headings: Seismic design; Coupling; Reinforced concrete; Shear walls. Author keywords: Seismic; Design; Coupled wall system; Reinforced concrete; Walls; Shear walls; Performance-based design; Analysis; Composite.

This paper focuses on the design and performance of a very tall mechanically stabilized earth (MSE) wall. Expansion of Seattle-Tacoma International Airport called for the construction of a third runway west of the two existing runways. A significant volume of compacted earth fill was required to raise the grade as much as 50 m to meet the level of the existing airfield. Nominal 2H: 1V fill slopes were used where possible, but MSE retaining walls were used where fill slopes would have encroached into existing wetlands. Consequently a four-tier 46-m-tall MSE wall was constructed along a portion of the western edge of the embankment. Performance monitoring included strain gauge-instrumented reinforcing strips, inclinometer installations with sondex settlement rings, optical survey of the wall facing for vertical and lateral movements, and piezometers. This paper describes wall design issues, aspects associated with the instrumentation of the wall, and the observed performance. Monitoring indicates satisfactory performance of the MSE wall and compares reasonably well with predicted performance. DOI: 10.1061/(ASCE)GT.1943-5606.0000294 CE Database subject headings: Soil stabilization: Retaining walls; Performance characteristics; Instrumentation; Design; Displacement; Washington; Airport and airfield runways. Author keywords: Soil stabilization; Retaining walls; Performance; Instrumentation; Design; Displacement.

In this paper, an analytical study considering the effect of uncertainties in the seismic analysis of geosynthetic- reinforced soil (GRS) walls is presented. Using limit equilibrium method and assuming sliding wedge failure mechanism, analysis is conducted to evaluate the external stability of GRS walls when subjected to earthquake loads. Target reliability based approach is used to estimate the probability of failure in three modes of failure, viz., sliding, bearing, and eccentricity failure. The properties of reinforced backfill, retained backfill, foundation soil, and geosynthetic reinforcement are treated as random variables. In addition, the uncertainties associated with horizontal seismic acceleration and surcharge load acting on the wall are considered. The optimum length of reinforcement needed to maintain the stability against three modes of failure by targeting various component and system reliability indices is obtained. Studies have also been made to study the influence of various parameters on the seismic stability in three failure modes. The results are compared with those given by first-order second moment method and Monte Carlo simulation methods. In the illustrative example, external stability of the two walls, Gould and Valencia walls, subjected to Northridge earthquake is reexamined. DOI: 10.1061/(ASCE)GT.1943-5606.0000289 CE Database subject headings: Structural stability; Limit equilibrium; Seismic design; Geosynthetics; System reliability; Walls; Soil structures; Earthquakes. Author keywords: Stability; Limit equilibrium; Seismic design; Geosynthetics; Reliability; System reliability.

The study proposes the simplification of the multilayer urban canopy model. Four types of multilayer urban canopy models--level 4, level 3, level 2, and level 1--are developed to reduce the computational load of the heat budget calculations at the wall surface. The level 4 model, which accounts for the wall directions and the vertical layer, is simplified in three ways: the level 3 model only accounts for the vertical layers, the level 2 model accounts for the wall directions, and the level 1 model accounts for neither the wall directions nor the vertical layer. From the simplification, compared to the level 4 model, the memory is reduced by 57%, 65%, and 72% for the level 3-level 1 models, respectively, when the vertical canopy layer is seven. At the same time, the CPU time is reduced by 67%, 70%, and 78% for the level 3-level 1 models. Then, each canopy model is compared with observations in Tokyo. The results show that the simulations from the four models are close to the observed ones, and the differences among the four models are very small. An additional model intercomparison study based on idealized simulations indicates that the level 3 model can be used instead of the level 4 model in any condition, whereas the level 2 and level 1 models are proposed to be used under conditions with a large sky view factor. DOI: 10.1175/2009JAMC2336.1

Process capability (PC) characterizes the variation in a parameter of a process's output. From a constructability perspective, investigating PCs for geometric variation is important when specifying tolerances for all construction processes. This paper investigates a case involving soldier piles used in a slurry wall and compares the design specified tolerances to as-built field data. As with other cases investigated by the writers covering many major construction processes, this case also shows that designers specify tolerances based on tacit estimates of variation limits, not PCs. Consequently, the PCs consistently exceed the design specified tolerances, preventing the possibility of proper tolerance management and causing problems to manifest during construction. The writers conclude that variation estimates are an inaccurate basis for specifying tolerances and instead should be based on PCs. DOI: 10.1061/(ASCE)CF.1943-5509.0000079 CE Database subject headings: Constructability: Lean construction: Design/build; Slurry walls. Author keywords: Tolerance: Process capability: Constructability: Lean construction: Design/build: Slurry walls.