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Plate anchors are commonly used to resist static, cyclic, and monotonic post-cyclic uplift loads. Under cyclic loading, progressive sudden failure may occur, characterized by accumulated displacement--even under loads significantly less than the static capacity. Despite extensive usage of geocell materials for increasing cyclic resilience, the influence of geocell reinforcements on cyclic uplift capacity is not well understood. In this study, a series of near-full-scale experimental tests, with and without geocell, are presented. Results show that the unreinforced system fails cyclically under a load that is almost 70% of its ultimate uplift capacity ([P.sub.u]), but use of geocell enables stable cyclic resistance of over 100% [P.sub.u]. For the given soil and configurations, a cyclic displacement rate that reaches less than 0.05 mm/cycle tends to highlight a likely stable response. Evaluation of the soil's response to cyclic loading demonstrates that, with increasing loading cycles, the loading is increasingly transmitted through the soil close to the anchor in the unreinforced case, but that the reinforced case is less prone to this phenomenon. The monotonic post-cycling capacity of both reinforced and unreinforced anchors decreases after application of cyclic loading; however, the unreinforced scenario demonstrates larger decreases in capacity, particularly in the residual capacity. Key words: anchor, uplift, geocell, cyclic loading, post-cycling behavior, large-scale testing. Les ancrages a plaque sont couramment utilises pour resister aux charges statiques, cycliques et monotones apres des charges de soulevement cycliques. Sous charge cyclique, une defaillance soudaine progressive peut se produire, caracterisee par un deplacement cumule, meme sous des charges nettement inferieures a la capacite statique. Malgre l'utilisation intensive de geotextile cellulaire pour augmenter la resilience cyclique, l'influence des renforcements de geotextile cellulaire sur la capacite de soulevement cyclique n'est pas bien comprise. Dans cette etude, une serie d'essais experimentaux avec et sans geotextile cellulaire, presque a pleine echelle, est presentee. Les resultats montrent que le systeme non renforce tombe en defaillance de maniere cyclique sous une charge representant pres de 70 % de sa capacite de soulevement ultime ([P.sub.u]), mais l'utilisation de geotextile cellulaire permet une resistance cyclique stable superieure a 100 % [P.sub.u]. Pour le sol et les configurations donnes, un taux de deplacement cyclique inferieure a 0,05 mm/cycle tend a mettre en evidence une reponse probablement stable. L'evaluation de la reponse du sol a la charge cyclique montre que, lorsque le nombre de cycles de charge augmente, la charge est de plus en plus transmise a travers le sol pres de l'ancre dans le cas non renforce, mais que le cas renforce est moins sujet a ce phenomene. La capacite monotone post cyclique des ancres renforcees et non renforcees diminue apres l'application du chargement cyclique; cependant, le scenario non renforce montre des diminutions plus importantes de la capacite, en particulier de la capacite residuelle. [Traduit par la Redaction] Mots-cles : ancrage, soulevement, geotextile cellulaire, chargement cyclique, comportement post-cyclique, essais a grande echelle., 1. Introduction The stability of various structures (e.g., masts, wind turbines, rock-fall protection fences) may directly depend on anchoring that may resist static and cyclic uplift loadings. Under cyclic uplift [...]

Landslide susceptibility maps indicate the spatial distribution of landslide likelihood. Modeling susceptibility over large or diverse terrains remains a challenge due to the sparsity of landslide data (mapped extent of known landslides) and the variability in triggering conditions. Several different data sampling strategies of landslide locations used to train a susceptibility model are used to mitigate this challenge. However, to our knowledge, no study has systematically evaluated how different sampling strategies alter a model's predictor effects (i.e., how a predictor value influences the susceptibility output) critical to explaining differences in model outputs. Here, we introduce a statistical framework that examines the variation in predictor effects and the model accuracy (measured using receiver operator characteristics) to highlight why certain sampling strategies are more effective than others. Specifically, we apply our framework to an array of logistic regression models trained on landslide inventories collected at sub‐regional scales over four terrains across the United States. Results show significant variations in predictor effects depending on the inventory used to train the models. The inconsistent predictor effects cause low accuracies when testing models on inventories outside the domain of the training data. Grouping test and training sets according to physiographic and ecological characteristics, which are thought to share similar triggering mechanisms, does not improve model accuracy. We also show that using limited landslide data distributed uniformly over the entire modeling domain is better than using dense but spatially isolated data to train a model for applications over large regions. Plain Language Summary: Landslide susceptibility maps show which areas in a region are more prone to landsliding than others. These maps are created from attributes of mapped landslides. The variation in landslide attributes and amount of landslide data required makes it difficult to map landslide susceptibility accurately over large regions. It is unclear whether any previously proposed methods to overcome these difficulties produce accurate susceptibility maps. Here, we develop a framework that evaluates the effectiveness of the following methods: using landslide data sets from only a few locations where data are readily available, applying models only to regions presumed to have landslide attributes similar to the regions used to develop the models, or gathering a few uniformly distributed (i.e., spread approximately equally) landslide data points. We show that the wide variation in landslide attributes over large regions reduces the accuracy of landslide susceptibility models that are developed using data from only a few locations. Restricting model application to regions with presumed similar attributes does not improve model performance. However, using a limited landslide data set that covers the entire region produces accurate susceptibility maps. Key Points: We use a statistical framework to investigate the influence of data sampling strategies on landslide susceptibility model performanceThe framework shows that the predictor data effects on output probability vary drastically with the sampling strategy usedThe best sampling strategy we evaluate uses landslide data sampled uniformly from the entire modeling domain [ABSTRACT FROM AUTHOR]

The effects of strong ground shaking on hillslope stability can persist for many years after a large earthquake, leading to an increase in the rates of post earthquake land sliding. The factors that control the rate of post‐earthquake land sliding are poorly constrained, hindering our ability to reliably forecast how landscapes and landslide hazards and risk evolve. To address this, we use a unique data set comprising high‐resolution terrestrial laser scans and airborne lidar captured during and after the 2010–2011 Canterbury Earthquake Sequence, New Zealand. This earthquake sequence triggered thousands of rock falls, and rock and debris avalanches (collectively referred to as "rockfall"), resulting in loss‐of‐life and damage to residential dwellings, commercial buildings and other infrastructure in the Port Hills of Christchurch, New Zealand. This unique data set spans 5 years and includes five significant earthquakes. We used these data to (a) quantify the regional‐scale "rockfall" rates in response to these earthquakes and the postearthquake decay in rockfall rates with time; and (b) investigate the site‐specific factors controlling the location of seismic and nonseismic rockfalls using frequency ratios and logistic regression techniques. We found that rockfall rates increased significantly in response to the initial earthquake that generated the strongest shaking in the sequence—The MW 6.2 22 February 2011 event—Compared to the long‐term background rates derived from the dating of pre‐2010 talus piles at the toe of the slopes. Non seismic rockfall rates also increased immediately after the 22 February 2011 earthquake and decayed with time following a power‐law trend. About 50% of the decay back to the pre‐earthquake rockfall rates occurred within 1–5 years after the 22 February 2011 earthquake. Our results show that the short‐term decay in rockfall rates over time, after the initial earthquake, was attributed to the subsequent erosion of seismically damaged rock mass materials caused by environmental processes such as rain. For earthquake‐induced rockfall at the regional‐scale, the peak ground accelerations is the most significant variable in forecasting rockfall volume, followed by the relative height above the base of the slope. For both earthquake and non‐seismic conditions at the site‐specific scale, the probability of rockfall increases when the adjacent areas have failed previously, indicating that accrued damage preconditions localized areas of the slope for subsequent failure. Such preconditioning is a crucial factor driving subsequent rockfalls; that is, future rockfalls are likely to cluster near areas that failed in the past. Plain Language Summary: Evidence from previous earthquakes suggests that the frequency of land sliding after a large earthquake is significantly higher than before it. Strong earthquakes cause slope cracking and generate landslide debris, which can be more readily remobilized post earthquake, creating new hazards, including further landslides and landslide dams. These hazards may persist for years and decades and represent a prolonged risk that the impacted communities must consider. Currently, the relative increase in land sliding and rate of decay during and after a major earthquake is rarely quantified, thus posing a knowledge gap for those rebuilding after a major earthquake. This paper explores high‐resolution terrestrial laser scan models of slope surfaces and how these surfaces changed during and after strong earthquake shaking during the 2010–2011 Canterbury Earthquake Sequence (CES) in New Zealand. These surface "change" models were used to quantify the volumes of debris–rock and soil–that fell from these slopes during and after the CES. These data were used to establish a regional‐scale, physical relationship between the volume of debris falling from the cliffs per earthquake or unit of time, per unit area of slope. Using the change models, we investigated the factors that control the temporal and spatial distribution of the rockfalls at the regional‐ and site‐specific scales. At the regional scale, we found that the size of the slope and the relative increase in rockfall rates above pre‐CES rates controlled the subsequent non‐seismic rockfall decay time. At the site‐specific scale, the main conclusions from this study are: (a) for earthquake triggers, the peak ground acceleration (a measure of earthquake ground shaking) was the most important variable in forecasting the probability of failure, followed by the relative elevation or height above the base of the slope; and (b) for both earthquake and nonseismic triggers, the probability of failure increases when the adjacent areas have failed previously, indicating that preconditioning of the slope to failure is a key factor driving subsequent rockfalls. Key Points: We quantify rock slope changes during and after a major earthquake sequence through repeat high‐resolution terrestrial laser scan surveysWe analyze landslide rates over 5 years, during and after the earthquakes at the regional‐ and site‐specific scalesNon seismic landslide rates are heightened immediately after the initial earthquake and decayed with time (1–5 years) following a power‐law trend [ABSTRACT FROM AUTHOR]

Clay minerals dominate the soil colloidal fraction and its specific surface area. Differences among clay mineral types significantly influence their effects on soil hydrological and mechanical behavior. Presently, the soil clay content is used to parameterize soil hydraulic and mechanical properties (SHMP) for land surface models while disregarding the type of clay mineral. This undifferentiated use of clay leads to inconsistent parameterization, particularly between tropical and temperate soils, as shown herein. We capitalize on recent global maps of clay minerals that exhibit strong climatic and spatial segregation of active and inactive clays to consider spatially resolved clay mineral types in SHMP estimation. Clay mineral‐informed pedotransfer functions and machine learning algorithms trained with datasets including different clay types and soil structure formation processes improve SHMP representation regionally with broad implications for hydrological and geomechanical Earth surface processes. Plain Language Summary: Understanding and predicting Earth's surface water and energy movement rely on accurate representation of soil properties, which are often estimated using simple‐to‐measure information such as soil particle sizes (soil texture) and other attributes, such as vegetation. Soil clay content is an important trait that affects the rate by which rainwater infiltrates the soil and potentially the stability of soil on steep hillslopes. Most models make no distinction between clay minerals despite large differences in clay mineral and soil properties between tropical and temperate regions. New global maps of clay minerals show strong climatic and spatial segregation of clay minerals that allow better estimates of fundamental soil properties. We developed models that use these clay mineral maps for estimating hydrological and mechanical properties for most soil types. These new equations will help to improve global predictions of water availability, erosion, and natural hazards. Key Points: Variations in clay mineral type significantly affect soil hydro‐mechanical properties for soils with similar clay fractionsRecent global maps of clay mineral type permit spatially resolved and physically based corrections of pedotransfer functionsThe new clay mineral‐informed soil properties are in agreement with measurements and resolve biases of undifferentiated use of clay faction [ABSTRACT FROM AUTHOR]

Expanded polystyrene (EPS) geofoam is commonly used as lightweight fill materials in wide range of geotechnical engineering applications including protection of buried utilities and pipelines. EPS blocks are usually placed next to buried pipelines to reduce the overburden and traffic-induced pressure on them. In this paper, a new configuration of EPS blocks around the buried utility is defined and its performance under traffic loading examined. The proposed configuration consists of three buried EPS blocks. Two blocks (posts) are vertically oriented, while a capping EPS block (beam) is placed atop, leaving a void to protect the buried utility. Finally, soil cover is placed and compacted above the beam. By considering sufficient void space, the protection system will carry all the imposed load, and no stress will be incurred to the protected utility. The effects of beam thickness, soil cover thickness, EPS density, free span length between the posts, and soil cover reinforcement on the system's behavior under cyclic loading were explored through large-scale laboratory model tests. System performance enhanced when high-density EPS blocks, thicker beam and soil cover were used. The results also showed that reinforcing the soil cover with a single layer of geogrid could significantly lower the blocks' deformations and control their dynamic strain rate under cyclic loading. Finally, a three-dimensional finite-element model was developed, validated against experimental results, and used to gain more comprehensive insight into the protection system's performance under loading. [ABSTRACT FROM AUTHOR]

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This study presents a series of numerical analyses investigating the impact of rainfall on the performance and design of geosynthetic-reinforced soil slopes (RSSs). The importance of considering regional hydrological conditions for designs of RSSs, particularly when marginal soil is used as backfill, is demonstrated and highlighted. RSSs with backfills containing five different fines contents subjected to various combinations of initial hydraulic conditions and major rainfall events were modeled. The input rainfall was determined from the rainfall intensity–duration–frequency (I–D–F) curves to realistically account for the impact of regional hydrological conditions. The hydraulic responses and stability of the RSSs including their porewater pressure development and factor of safety were then evaluated and compared. The results revealed that the applied rainfall scenarios had little influence on the performance of RSSs with high-quality backfills (i.e. backfill with low fines content), whereas those with prolonged rainfall duration substantially affected the performance of RSSs with high fines content backfills. Rainfall thresholds were established for the RSSs with various backfills and initial conditions and compared with the regional I–D–F curves to provide a simplified and robust method for facilitating backfill selection and assessing the failure risk of RSSs. [ABSTRACT FROM AUTHOR]

Expanded polystyrene (EPS) is a lightweight material commonly used in sensitive geotechnical applications, particularly in transportation applications that often see a confluence of buried utilities and traffic loading. This study investigates the behavior and efficacy of EPS geofoam post-beam (PB) systems as a means of protecting underground utilities. The PB system consists of two EPS geofoam 'post' blocks that both protect buried utilities and support a capping EPS beam and soil overburden. Two series of laboratory large-scale model tests of the EPS PB system under both unreinforced and geogrid-reinforced soil cover were conducted to explore the effect of beam thickness, soil cover thickness and density of geofoam blocks on system deformations and stress distributions. Experimental results showed that the EPS PB system was effective in bearing the applied load without transferring it to the utilities below. The improvement in system performance was most pronounced when higher geofoam density, thicker EPS beams, geogrid reinforcement and increased soil cover were used. Three-dimensional finite element (FE) numerical models were developed and validated based on test results, and leveraged to provide insight into internal system behavior and design parameter selection. [ABSTRACT FROM AUTHOR]

Use of geosynthetic reinforcement may improve the performance of many geotechnical systems, including anchors. In this study, the uplift capacity of geocell-reinforced sand is studied based on a series of near large-scale experiments and calibrated three-dimensional Finite Element (FE) models. Using the verified FE models, a comprehensive parametric study of over 270 models was performed to assess the influence of friction angle, geocell stiffness, embedment depth, anchor size, and geocell-anchor width ratios on uplift capacity. Uplift capacity increases with embedment depth and friction angle, but the relative increase is more pronounced for loose sand. The observed shape effects are amplified in reinforced installation. The increase in uplift capacity observed decays for geocell-anchor width ratios greater than 3, but an increase in geocell stiffness demonstrates increased uplift capacity through the increased mobilization of geocell resisting uplift. Finally, based on the verified numerical models, a semi-empirical equation is proposed to enable estimation of uplift capacity in geocell-reinforced sand, demonstrating good agreement with results from numerical simulations. [ABSTRACT FROM AUTHOR]

Lateral spreading is a prevalent geotechnical problem associated with earthquake-induced liquefaction, often occurring at gentle slopes of loose, saturated sand near bodies of water and causing significant damage to buried utilities. This study presents a deterministic approach to analyse lateral spreading behaviour using a modified Newmark analysis applied to a column of sliding blocks with degrading yield accelerations. The proposed sliding column approach exhibits reasonable agreement with a well-instrumented centrifuge test evaluating free-field lateral spreading. The analysis captures lateral spreading displacement throughout a soil profile, as well as shear strains and simplified earth pressures. The effect of light cementation is investigated, demonstrating notable arrest of lateral spreading displacements and pressures. Free-face effects are also evaluated for a liquefying layer of soil beneath a gentle, competent crustal slope, demonstrating notable lateral spreading behaviour with larger inclinations of liquefying soil. However, lateral spreading still occurred when considering a horizontal liquefying layer, realised due to inertial loading and differences between confining boundary forces. The approach can be utilised to efficiently analyse lateral spreading across a large spatial extent. [ABSTRACT FROM AUTHOR]

Reinforced soil has become a common means of retaining soil and supporting spread footings due to ease of construction and cost-efficiency. However, the behavior of these structures under service state conditions is inherently complex and dependent on the selection of design factors. Factors that govern design include earth pressures, settlements and reinforcement strains, but are not easily attained from closed form solutions. This study aims to provide insight into the complex behavior of reinforced soil walls surcharged by a discrete footing in context of these design factors, facilitating the development of a numerical model. A nonlinear elastic-plastic constitutive soil material model was calibrated to experimental plane strain test data, while the performance of a wall model was compared against full-scale laboratory testing of an identical geosynthetic-reinforced wall from prior literature, demonstrating satisfactory agreement. This agreement enabled a parametric study of the same wall model with a discrete spread footing evaluating the effects of reinforcement type and vertical spacing, footing location, footing dimensions, and toe restraint on lateral earth pressure distributions, wall deformations and reinforcement strains. The results of the study demonstrated that simplified consideration of only reinforcement type on service-state performance of reinforced walls neglects the effects of closely spaced reinforcements on behavior. Use of closely spaced reinforcements created increased earth pressures, but also reduced lateral displacement, footing settlements and reinforcement strains. Furthermore, it enabled achievement of equivalent service state criteria for footings located closer to the wall facing, potentially enabling increased right-of-way or reduced deck length when supporting a bridge superstructure. [ABSTRACT FROM AUTHOR]

Distributions of landslide size are hypothesized to reflect hillslope strength, and consequently weathering patterns. However, the association of weathering and critical zone architecture with mechanical strength properties of parent rock and soil are poorly-constrained. Here we use three-dimensional stability to analyze 7330 landslides in western Oregon to infer combinations of strength - friction angles and cohesion - through analysis of both failed and reconstructed landslide terrain. Under a range of conditions, our results demonstrate that the failure envelope that relates shear strength and normal stress in landslide terrain is nonlinear owing to an exchange in strength with landslide thickness. Despite the variability in material strength at large scales, the observed gradient in proportional cohesive strength with landslide thickness may serve as a proxy for subsurface weathering. We posit that the observed relationships between strength and landslide thickness are associated with the coalescence of zones of low shear strength driven by fractures and weathering, which constitutes a first-order control on the mechanical behavior of underlying soil and rock mass., (© 2022. The Author(s).)

Partial results of a NIOSH-funded study for "Protecting the Logging Workforce: Development of Innovative Logging Techniques for a Safer Work Environment" by a team of researchers at Oregon State University are presented that review safety in steep slope logging. Comparisons are made for hazards and exposures of "conventional" and new technologies for steep slopes. Hazards of new technologies are identified. Safety assessments are addressed for forestry sectors internationally, for the firm and for workers. Important questions of technical feasibility, economic viability and environmental performance are raised. Ongoing research on operators using tethered and untethered systems are described. Results will help inform training and selecting operators. New Best Operating Practices and safety code regulations will result from the research. New technologies will reduce worker hazards and exposures for steep slope logging.