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• This paper presents a drained expansion solution of a cylindrical cavity with fabric change effect in the sand. • The problem is formulated as a system of first-order differential equations with the known variables. • A user-defined SANISAND model is implemented as a subroutine, which is applied to FEM simulation. Sandy soil exhibits inherently anisotropy due to its microstructure, also known as 'fabric'. However, the drastic change in fabric observed during the dilatant phase is often overlooked in current cavity expansion research. This paper presents a drained expansion solution of a cylindrical cavity with fabric change effect in the sand using a simple non-associated and anisotropic model, SANISAND. The problem is formulated as a set of first-order differential equations with the unknown variables as functions of an auxiliary coordinate, which can be solved as an initial value problem. A subroutine is implemented into the FEM simulation to verify the proposed method. Additionally, cavity expansion solutions in sand are compared with those based on state-dependent dilatancy. The anisotropic fabric of the sand is studied to investigate the impact of the initial void ratio, initial mean stress, and at-rest coefficient on the void ratio path, stress distributions and paths, and bounding surfaces. The proposed solution provides a framework for the potential use of cavity expansion in sand, considering the fabric change effect, and a benchmark for further developments and numerical calculations by using the SANISAND model. [ABSTRACT FROM AUTHOR]

A modified strain wedge model for analyzing the lateral response of reinforced concrete piles in sand is proposed in this paper. To address the limitations of the strain wedge model, the relationship between the lateral displacement of the pile and the soil strain is modified. This modification comprehensively considers the effects of the global compression of the soil and the local angle of the pile on the soil strain. The validity and accuracy of the proposed model are verified by published centrifuge test results and field test results. Finally, the effects of pile materials, pile geometry, and pile head boundary conditions on the lateral response of reinforced concrete piles in sand are discussed. • A modified SW model is proposed to analyze the plasticity development of RC piles subjected to lateral load in sand. • The model modifies the relationship between pile displacement and soil strain using layer-by-layer area equivalence. • The effects of material, geometry and boundary of piles on the plastic behavior of RC piles are discussed using this model. [ABSTRACT FROM AUTHOR]

Revealing lateral soil bearing mechanism around an offshore monopile is critical for understanding and solving soil-pile interactions. In this paper, the lateral bearing mechanism around an offshore monopile in sand is analyzed and a corresponding analytical method is established. Three soil bearing mechanisms, including wedge-type flow, triaxial extension and volume compression, near mudline under working load level are proposed by analyzing the distribution of the Lode's angle (θ L) and soil displacement vectors. A corresponding analytical method to calculate the lateral response of the monopile is developed based on the strain wedge (SW) model. The proposed model is verified through three pile tests. Finally, the effect of the parameters of Duncan-Chang model on the monopiles in dry and saturated sand is discussed. • Wedge-type flow, triaxial extension, and volume compression around a laterally loaded monopole are clarified. • The reasons for the formation of the three soil bearing mechanisms are explained. • A simplified analytical method considering the three soil bearing mechanisms is established to calculate monopile behaviors. • The clarification of the soil bearing mechanisms is useful for understanding and solving soil-pile interactions. [ABSTRACT FROM AUTHOR]

The reliability of monopiles is paramount for the uninterrupted operation of offshore wind turbines. However, this reliability is often challenged by environmental factors, such as scour and corrosion, as well as the inherent uncertainty in loads, soil properties, and environmental variables. Therefore, this study proposes a time-variant non-probabilistic reliability assessment strategy for laterally loaded offshore monopiles under scour and corrosion. This strategy is grounded in non-probabilistic interval and interval process models, along with a lateral response analysis of soil-pile system that accounts for the effects of scour and corrosion. The time-variant reliability index is determined using an enhanced HL-RF algorithm. The application of this method to specific cases of laterally loaded monopiles under scour and corrosion demonstrates its remarkable feasibility and adaptability, even for high-dimensional uncertainty scenarios. Furthermore, a sensitivity analysis, based on the proposed strategy, enables the identification of uncertain parameters that significantly impact monopile reliability, providing valuable insights for practical engineering applications. Additionally, this framework has the potential to be extended for a more comprehensive evaluation of the fatigue characteristics of offshore monopiles, an area that merits further exploration. • The study gives a time-variant non-probabilistic reliability assessment strategy for laterally loaded offshore monopiles. • The time-variant reliability index is determined using an enhanced HL-RF algorithm. • The proposed strategy enables the identification of uncertain parameters that significantly impact monopile reliability. [ABSTRACT FROM AUTHOR]

The paper introduces a semi-analytical approach for predicting the pile-soil response under cyclic lateral loads in sands, incorporating the cavity expansion/contraction theory with an anisotropy and non-associated constitutive model, Simple ANIsotropic SAND (SANISAND). The pile hole is regarded as a cylindrical cavity, and the cyclic loading process is reasonably treated as a cavity expansion/contraction problem. A superposition principle is introduced to determine the superimposed stress states around the cavity. The geometric relationship, quasi-static equation, and boundary conditions are integrated into a standardized solving procedure to obtain the stress-strain distribution surrounding the pile. Subsequently, the derived cyclic p-y curve is used in conjunction with the deflection equilibrium differential equation and finite-difference method to determine the pile-soil response under lateral cyclic load. The method's validity and capacity are further demonstrated through two well-examined centrifuge tests, which shows a good agreement with the experimental data. The cumulative deformation, hardening and ratcheting behaviors of pile-soil system can be captured in this study, which provides a novel approach to figure out the pile-soil response in sands under cyclic lateral loads. • This paper presents a semi-analytical approach for predicting cyclic laterally loaded pile-soil interaction in sands. • The soil deformation mechanism around the pile is determined using the constitutive model, SANISAND. • The hardening and ratcheting behaviors of pile-soil system during cyclic lateral loading process can be captured. [ABSTRACT FROM AUTHOR]

Afforestation is an important aspect of ecosystem restoration (ER) and poverty alleviation (PA) through direct and indirect social, economic, and environmental effects. However, the existing afforestation projects worldwide have mainly viewed economic benefits through the narrow lens of subsistence and livelihood, thereby underestimating both indirect PA and the associated negative effects on agricultural production when formulating long-term solutions to global poverty. This study aimed to systematically examine the ecological, agricultural, and economic effects of ecosystem restoration in southeastern China over four decades based on biophysical models and statistical records, and further proposed an upgraded strategy for sustainable PA through ER that addresses conservation objectives and resource needs. We found that ER promoted vegetation growth and enhanced carbon sequestration and soil retention. Meanwhile, industrial transformation improved the economic scale and livelihood diversity (i.e., disposable income), which alleviated poverty and improved social services and infrastructure conditions. Nevertheless, the secondary and tertiary industries gradually replaced the primary industry in terms of output, and increased animal husbandry and forestry development weakened crop planting. Planting structure adjustments further threatened the stability of the grain supply, particularly after 1999, which could potentially lead to a grain crisis. Therefore, we propose upgraded forest management and coordinated development policies to avoid a grain crisis, improve livelihood diversity, balance multidimensional benefits, and facilitate sustainable development. Study results serve as a valuable reference for policy formulation and ER measures for more inclusive, resilient, and sustainable PA. [Display omitted] • Ecosystem restoration promoted vegetation growth and enhanced carbon sequestration and soil retention. • Industrial transformation alleviated poverty and improved social services and infrastructure conditions. • Increased animal husbandry and forestry development weakened crop planting. • Planting structure adjustments threatened the stability of grain supply. • Upgraded forest management and coordinated policies were proposed for sustainable development. [ABSTRACT FROM AUTHOR]

The scour has a great influence on the stability of pile. Most of the current research only focuses on the lateral behavior of pile under lateral load, rarely on that under combined lateral and vertical loads under scour. In this paper, an analytical model is proposed to study the effect of scour on lateral response and pile-soil interaction mechanisms of pile in sand under combined lateral and vertical loads. This model considers the intercoupling effect between lateral load and vertical load, which is mainly embodied in: (1) the pile-soil separation effect, the enhancement effect of soil stress level in front of pile and friction effect caused by lateral load; (2) P-Δ effect and friction effect caused by vertical load. The comprehensive influence of additional stress caused by the remaining soil above post-scour ground and stress history on the soil properties is analyzed, thus, the ultimate soil resistance and the lateral subgrade modulus after scour are accurately evaluated. Finally, the accuracy of the analysis model is verified by comparing it with the results of existing cases, and the influence of vertical load, scour depth, additional stress and stress history on the lateral response of pile is analyzed. [ABSTRACT FROM AUTHOR]

Rigid piles are prevalent in offshore engineering, and the utilization of the failure envelope approach in foundation design is a burgeoning trend. Nevertheless, in contrast to shallow and skirted foundations, the exploration on the failure envelope for deep-embedded foundations remains comparatively scant. Notably, among the existing failure envelopes for rigid piles, scant attention is paid to the soil strength gradient, which is a pervasive aspect of self-weight consolidated seabed. Therefore, this study endeavors to develop a failure envelope for offshore rigid piles under combined horizontal-moment loading in clay with linearly increasing undrained shear strength. This endeavor is achieved by employing an inclined ellipse framework and separately deriving the characteristic parameters against corresponding failure mechanisms. Subsequently, validation against FELA cases and tests reveals that the proposed equations effectively capture the essential characteristics of the failure envelope and offer fair predictions in terms of bearing capacity. Furthermore, comparative analyses with previous solutions underscores the superiority of the proposed method in scenarios involving rigid piles and linearly increasing soil strength profiles. Additionally, a parametric analysis demonstrates that as the soil strength gradient intensifies, the long axis of the failure envelope presents a notable expansion, emphasizing the imperative of incorporating the soil strength gradient in practical design considerations. • A failure envelope for offshore rigid piles under combined horizontal-moment loading in clay is developed. • The proposed equations can generally capture the main features of the failure envelope. • The proposed method possesses superiority in cases of rigid piles and linearly increasing soil strength profiles. [ABSTRACT FROM AUTHOR]

Since 2007, persistent green tides in the Yellow Sea of China (YSC) have inflicted substantial economic and social losses. In response, the Chinese government has enacted various policies to mitigate these impacts. This study introduced an evolutionary-multiple streams framework and employed Social Network Analysis (SNA) and Text Analysis from 2007 to 2023, tracing three phases of policy development: growth (2007–2012), stability (2013–2017), and explosion (2018–2023). Findings indicated that during the growth phase, the most of the policy themes were "monitoring" and "emergency"; in the stability phase, policy issuance by provincial and municipal agencies began to increase; in the explosion phase, a basic consensus was reached on source control and intergovernmental cooperation in the management of green tides. Themes such as "ecology", "extreme weather", and "green tide exploitation" have been emphasized. This analysis provides insights for future policy formulation in green tide control and broader marine environmental governance. • An evolutionary-multiple streams framework is applied to analyze green tide policies. • Policymakers are increasingly valuing ecological protection and resource utilization. • The study serves as a crucial reference for advancing green tide control measures. [ABSTRACT FROM AUTHOR]

Piles are inevitably installed on sloping coastlines or inclined seabeds to support offshore wind turbines, offshore bridges, and other structures. The objective of this paper is to develop an analytical method for investigating the lateral response of short piles near clay slopes. The soil-pile interaction is modelled by a two-spring model which is used to describe the soil resistance around the pile and the horizontal shear force at the pile base. Considering the combined effect of slope angle and near-slope distance, the ultimate soil resistance along the pile is divided into three cases based on the nearby soil flow mechanism. The soil-pile-slope surface deformation mechanism is established according to the rotational deformation characteristics of short piles. In contrast to the modification of the initial stiffness, the p-y curve around the pile is constructed by considering the deformation mechanism. The accuracy of the analytical method is verified by comparing its results with two piles on level ground and five piles near slopes. Considering the soil-pile-slope deformation mechanism, the secant stiffness of the p-y curve is automatically adjusted and reduced without the need for additional numerical simulations or pile tests to determine the reduction factor of the initial stiffness. • A method is proposed for the analysis of laterally loaded short piles near clay slopes. • The method considers both the soil flow mechanism and the slope surface deformation mechanism. • The slope surface deformation mechanism is introduced into the framework of the p-y curve. • The framework automatically adjusts and reduces the secant stiffness of the p-y curve. [ABSTRACT FROM AUTHOR]

[Display omitted] • Anisotropic FCG of SLM AISI 420 in two build directions was studied. • FCG resistance is greater for loading direction parallel to the build direction. • FCGR difference between two build directions decreased after post-tempering. • Elongated cellular structure dominated anisotropy of FCG behavior. • Tempered martensite had greater effects on FCGR of perpendicular direction. This study investigated the fatigue crack growth (FCG) behavior of selectively laser-melted AISI 420 martensitic stainless steel built in two directions. The effect of tempering treatment at 400 °C was considered. In both as-built and tempered conditions, the parallel orientation exhibited lower fatigue crack growth rates (FCGRs) than the perpendicular orientation, indicating an anisotropic FCG behavior. Tempering treatment moderately reduced the anisotropy of FCG behavior, as the difference in FCGR between the two build orientations decreased in the tempered state. The anisotropic FCG behavior was attributed to the interaction between the crack path and the elongated cellular structure. Tempered martensite had a greater influence on the FCGR of the perpendicular group over the parallel group in tempered state. [ABSTRACT FROM AUTHOR]

This study proposes a nonlinear analytical method to predict the response of combined loaded offshore rigid monopiles near sandy slopes. Considering the slope effect, the method discusses the ultimate soil resistance before and behind the pile separately. The method assumes that the subgrade reaction modulus varies nonlinearly with relative density but linearly with depth. The equilibrium equation for the pile-soil system is obtained from the balance of forces and moments. By analyzing four mechanical models of rigid monopiles under combined loading and selecting three of them as the basis, a failure mode determination method is provided. The accuracy of this method is verified by comparing with indoor model test, 3D FEA model test and centrifugal test. [ABSTRACT FROM AUTHOR]

In this paper, a systematic study of the soil – pile interaction of a laterally loaded pile in proximity to undrained clay slope is conducted. The emphasis is on a modified actual displacement of the induced soil resistance in the p – y curve criterion by considering the displacement of the slope surface. On the above basic, the effect of slope on the ultimate soil resistance is also considered. A new p – y curve criterion, which divides the p – y curves in front of the pile into three cases, is proposed. Finally, the accuracy of the new model is verified through a pile test and two hyperbolic p - y curve criterions. The new criterion not only automatically reduces the stiffness of the p - y curve, but also reasonably reveals the effect of slope on the soil-pile interaction. [ABSTRACT FROM AUTHOR]

• This paper presents an analytical approach for predicting laterally loaded pile-soil interaction in saturated soils. • The soil deformation mechanism around the pile is determined using the constitutive model, MCC. • The p-y curve is derived by considering axisymmetric condition, equilibrium equation, and boundary conditions. This paper proposes an application of the cavity expansion theory to predict the load-displacement response of monotonically laterally loaded piles and the effective stress distribution of saturated modified Cam-clay (MCC) soil surrounding the pile. This approach incorporates geometric relationship, equilibrium equation, and boundary conditions to derive governing equations. These equations are subsequently solved to obtain monotonic p-y curves, which encompass the elastic, elastoplastic, and critical processes. To determine the load-displacement behavior and effective stress distribution of the soil, the proposed approach combines the deflection equilibrium differential equation with the finite-difference method. The accuracy and effectiveness of the approach are validated through a comparison with a Finite Element Method (FEM) simulation. Parametric studies are also presented to investigate the effects of overconsolidation ratio, in-situ coefficient, and mean effective stress. The validity and capacity of the proposed model are further demonstrated using model pile tests. The results affirm that this approach can well predict the monotonic load-displacement response of the pile and effectively captures important phenomena observed in pile tests. [ABSTRACT FROM AUTHOR]

In actual pile engineering, the laterally loaded offshore pile built near slope is not embedded in uniform clay or sand seabed, but layered soil seabed of different types and properties. For this purpose, a method is proposed to solve the lateral characteristics of offshore pile installed near layered slope in this paper. Based on the interaction force between layered interfaces and the concept of equivalent depth, an equivalent failure wedge model is constructed to evaluate the ultimate soil resistance of each layer of soil. It is assumed that the horizontal subgrade reaction modulus of sand in each layer changes nonlinearly with depth, while the horizontal subgrade reaction modulus of clay in each layer remains unchanged. And the influence of pile diameter and slope effect on the horizontal subgrade reaction modulus is considered. The results obtained in this paper are compared with the field test results and FE results, and the accuracy of the proposed method is verified. The analysis shows that the smaller diameter has the greater impact on the lateral deflection of pile head under the same growth range of diameter. When the pile diameter changes from 1 D to 1.5 D , the lateral deflection of pile head decreases by 42%. • A method is provided to solve the lateral behavior of offshore pile installed near layered slope with different soil properties. • Based on the concept of equivalent wedge, the failure wedge model is improved and extended to the layered soil to calculate the ultimate soil resistance by considering the layered characteristics of soil, the interaction force of the layered interface and the continuity of soil reaction. • The influence of pile diameter and slope effect on the horizontal subgrade reaction modulus is considered. [ABSTRACT FROM AUTHOR]

A cyclic p − y curve model is proposed to study the lateral response of piles in sand under two-way cyclic loads such as wind and wave. The collapse and densification of the soil around the pile caused by the repeated formation of the gap between the pile and soil during the cyclic loading are considered in the proposed model. Based on the nonlinear strain wedge model, the cyclic p − y curve is preliminarily constructed considering the friction characteristics. A collapse and recompression model of sand is established to account for the variation of the relative density of the caved soil and the characteristics of the pile-soil gap. The densification of sand caused by recompression is evaluated using the stiffness hardening index model. The cyclic p − y curve is modified by considering the collapse and densification of sand and its rationality is verified by comparing the results of calculation and centrifugal model test. Furthermore, the strengthening by the caved soil, the characteristics of the cyclic p − y curve, and the soil resistance are analyzed. • A cyclic p-y model considering the collapse and densification of sand is proposed to study the two-way response of piles. • A collapse and recompression model of sand is constructed to describe the influence of the caved soil. • The cyclic p-y curve model is modified by combining the collapse model and the densification model. [ABSTRACT FROM AUTHOR]

• The paper presents an analytical method for predicting the soil-structure interaction of axially loaded piles in sands incorporating the two-surface plasticity model. • 2-D stress–strain state of the soil-structure interface and the shear band is figured out, and 3-D elastoplastic behavior of soil around the shear band is determined. • A FEM simulation is performed with a user-defined subroutine and parametric study of the initial void ratio is conducted. The paper proposed a novel and practical analytical method for predicting the soil-structure interaction in sands. To well capture the stress softening and soil dilatancy behaviors during loading, a developed two-surface plasticity model for interface shearing is adopted to determine the 2-D stress–strain state of the soil-structure interface and the shear band, while the 3-D elastoplastic behavior of soil around the shear band is determined by another developed two-surface plasticity model for triaxial compression. Following a standardized solving procedure, the rigorous derivation for the stress–strain relationship in plastic zone is formulated as a system of first-order differential equations, which are solved as an initial value problem. Combined with the finite difference method (FDM), the load–displacement response of the axially loaded pile and the stress–strain state around the pile are presented. To verify the proposed analytical approach, a FEM simulation is performed using a user-defined subroutine. The soil with different initial void ratios ranging from very dense to loose is also modeled to demonstrate the effect of the initial void ratio on soil-structure response. The proposed analytical approach is also validated against centrifuge tests and field tests, manifesting the validity and capability of the proposed method. [ABSTRACT FROM AUTHOR]

The paper proposes a rigorous analytical approach to predict interaction between torsionally loaded piles and saturated clay soils. The soil deformation mechanism around the pile is determined using the non-associated and anisotropic constitutive model, SANICLAY, along with the axisymmetric condition, equilibrium equation, and boundary conditions. By solving the derived governing equations, the hoop shear stress against rotation curve is obtained, including elastic, elastoplastic, and critical state processes. Taking advantage of the finite-difference method, the torque-rotation behavior of the pile and the stress-strain state of the soil around the pile are figured out. The proposed approach is compared with a FEM simulation and a parametric analysis is conducted to investigate the effect of overconsolidation ratio and in-situ coefficient. Model pile tests and field tests are used to manifest the validity and capacity of the model. The results demonstrate that the present approach can well predict the torque-rotation response of the pile and can reflect some important phenomena observed in pile tests. • This paper presents an approach for predicting soil-pile interaction of torsionally loaded piles in saturated soils. • The soil mechanism around the pile is determined using the non-associated and anisotropic constitutive model, SANICLAY. • The stress-rotation curve is derived by considering axisymmetric condition, equilibrium equation, and boundary conditions. [ABSTRACT FROM AUTHOR]

This paper proposes an analytical model for calculating the lateral response of piles in homogeneous sand by considering inhomogeneous disturbance characteristics distribution. The disturbed soil in front of the pile is separated into strain wedge (SW) model elements, with the characteristics of each element calculated through coordinated pile-soil deformation. The limit of the stress level of the SW model element is also considered, and two geometric characteristic distributions are provided. A hyperbolic model is used to calculate the shear stress on the pile side. The proposed model is verified through four pile tests, and the accuracy of the new model is demonstrated by comparison. Additionally, the distributions of soil strain, stress level, fan angle and three critical depths are discussed. The results demonstrate that the model can realistically reveal the inhomogeneous stress–strain status distribution and geometric characteristics of the disturbed soil. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A significant decrease in sediment yield during the past six decades was detected. • The contribution of anthropogenic activities to sediment yield was quantified. • The multi-temporal scale flow–sediment relationship was evaluated. • Dam construction played an important role in sediment yield reduction. Abstract The water and sediment yields of rivers are changing substantially under the impacts of climate variability and anthropogenic activities, which are increasingly becoming an important research topic in the field of hydro-environmental science. This study presents a comprehensive investigation of the changes in runoff depth (h), specific sediment yield (SSY), and flow-sediment relationship at multi-temporal scales in the Han River Basin (HRB). The effects of climate variability and anthropogenic activities on SSY were quantified by employing double cumulative curve analysis. The results are as follows: (1) The annual and flood season h and SSY in the midstream (Huangzhuang Station) during the past six decades presented declining trends. The detected change points (i.e., 1968 and 1984) in SSY were linked to the reservoir and dam construction and soil and water conservation programs. The Danjiangkou (DJK) Reservoir impounded water in the flood season and supplied water in the non-flood season, which made the intra-annual distributions of h and SSY more even and the intra-annual variations more moderate in the comparisons between the pre- and post-change periods. (2) The annual and flood-season flow-sediment relationships were fitted with the power function and the sediment productive ability of runoff in the flood season was much greater than that in the non-flood season. The construction and operation of the DJK Reservoir intercepted a significant quantity of sediment; thus, the sediment transported by unit runoff largely declined. (3) The estimated relative contributions of climate variability and anthropogenic activities to the changes in SSY suggested that the anthropogenic activities played a more substantial role in the SSY decline after the transition years. Sustainable development of the HRB will face many challenges as the water and sediment discharges decrease further from the Han River into the Yangtze River. These results will provide a reference for better soil and water resource conservation and draw more attention to strengthen the river basin management. [ABSTRACT FROM AUTHOR]

Highlights • We quantified the soil erosion change in a spatially explicit manner. • We investigated the driving forces of soil erosion change. • The hydrological effects of soil and water conservation were assessed. • The limitations and sustainability of soil and water conservation were discussed. Abstract Land degradation is a global environmental problem that threatens human safety and socioeconomic development. In order to alleviate severe soil erosion, China has implemented historically unprecedented large-scale afforestation. In this study, we selected the most severely eroded Loess Plateau as a case, to assess the effectiveness of soil and water conservation (SWC) efforts based on the Revised Universal Soil Loss Equation. In addition, the underlying drivers for soil erosion changes and hydrological effects of SWC were investigated, and finally the potential policy implications of our findings were discussed. The soil erosion intensity from 2000 to 2015 was weakened largely due to favorable climate conditions and SWC efforts, which promoted vegetation restoration and enhanced soil retention. However, there was a significant trade-off between water provision and soil retention functions. The excessively artificial afforestation reduced sediment yield but depleted surface runoff. Furthermore, artificial afforestation and increasing irrigation water consumption overused groundwater resources and finally lowered groundwater table. The SWC efforts characterized by artificial afforestation induced soil moisture declining, particularly for the conversion type of farmland to forest/shrub. Our results suggested that afforestation might be a poor choice in arid and semiarid regions, because it did not consider local precipitation conditions, and have exacerbated water shortages and offset SWC efforts. Therefore, the future ecological restoration efforts should be transformed from simple species-based measures to optimal plant species combinations to minimize the tradeoff between water yield and soil retention. The strategies for ecological restoration of drylands should also account for water balance to ensure effectiveness and sustainability. [ABSTRACT FROM AUTHOR]

Highlights • Wind erosion status was assessed in the most seriously eroded area of China. • The constraint effects among climate, vegetation, and soil erosion were revealed. • The underlying drivers for wind erosion were investigated. • The implications of constraint effects on land degradation control were discussed. Abstract Soil erosion is a widespread environmental problem, which threatens the environmental sustainability. The northwest arid region (NAR) in China is known as one of the most severe soil loss in the world that suffering from wind erosion. Based on the Revised Wind Erosion Equation (RWEQ), the spatio-temporal change of wind erosion was identified, and the underlying drivers and influencing factors of soil erosion process were investigated. In addition, the implications of constraint effects in soil erosion control were discussed. The results showed that the wind erosion from 1990 to 2013 was substantially lessened, and the government-aided desertification prevention and control programs, as well as increasing precipitation and decreasing wind speed might have contributed to these trends. The constraint line analyses indicated that the vegetation cover had nonlinear and threshold effects on soil erosion through constraining the water condition (precipitation). Specifically, when the precipitation is below the threshold (approximately 50–100 mm yr−1 in the NAR), the precipitation (water condition) is not sufficient to maintain a good vegetation cover (about 20–40%), therefore the vegetation cannot efficiently prevent wind erosion. However, once the precipitation exceeds this threshold, the vegetation's sand retention function will enhance and thereby reducing soil loss substantially. Vegetation cover has a lower and an upper threshold for controlling wind erosion. A plant cover lower than 10% does little to reduce wind velocity at the soil surface. The effect of vegetation on reducing wind erosion basically reaches the maximum when plant cover is 40% or above. The constraint effects of precipitation on vegetation cover in the arid region should be considered to improve the efficiency of afforestation and reforestation efforts aiming at mitigating and preventing soil loss. [ABSTRACT FROM AUTHOR]

Bored piles constructed in permafrost regions often need to be socketed into weak and weathered rock strata, such as marl stratum. When these strata are ice-rich, the meltwater caused by construction will form an ice film at the pile-rock interface during refreezing, leading to a reduction in pile bearing capacity. By analyzing the shear mechanism of pile-rock interface with ice film, an interface shear model was proposed in this paper. Based on this model, the load transfer analytical method of rock-socketed bored piles was improved. Finally, the effects of pile-rock interface roughness, ice filling degree, and residual friction angle on skin friction were analyzed. The results show that the shear stress-displacement curve of the ice-containing interface unit exhibits two peaks and can be divided into four stages: ice film shear stage, ice film extrusion stage, concrete-rock relative sliding stage, and interface residual sliding stage. Increasing either the dilation angle or half-wavelength can improve the interface's shear resistance when only one variable is altered. Furthermore, the peak shear strength of the interface decreases as the filling degree increases. The interface residual shear stress is positively correlated with both the residual friction angle of weak rock (ϕ u − r) and ice (ϕ i − r), and increasing the proportion of ice in the residual sliding surface will lead to the reduction of residual shear stress. • In the presence of ice interlayer at pile-rock interface, the shear process can be divided into four stages. • The calculation model of skin friction for rock-socketed piles in ice-rich permafrost regions was improved. • The effects of interface roughness, ice filling degree, and residual friction angle on skin friction were analyzed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Anisotropic fracture toughness of AISI 420 built by selective laser melting is found. • Effects of tempering treatment and microstructure on the anisotropy are studied. • Fracture toughness is greater for loading direction parallel to the build direction. • Elongated cells are mainly responsible for the anisotropic behavior. • Fracture toughness is enhanced by a tempering treatment at 400 °C. Anisotropic fracture toughness of selective laser melted AISI 420 built in two build directions was investigated. Post-process heat treatments were performed at 200 °C and 400 °C to study the tempering effect. The parallel group exhibited better fracture toughness than the perpendicular group in both as-built and tempered states. K IC value of the 400 °C tempered state was superior to that of other states due to a coarser martensite phase. Elongated cellular structure was responsible for the anisotropic behavior because of a build direction effect, while the anisotropy was barely changed by the tempering treatments. [ABSTRACT FROM AUTHOR]

Large-scale plantations of Moringa oleifera Lam. are carrying out in the dry-hot valley of Red River in Yunnan Province to make it the core cultivation area in China. Nevertheless, there is a deficient understanding of detailed pollen flow patterns, which leads to uncertainty in designing and managing seed orchards of M. oleifera to fit the breeding demand. In order to facilitate the design of breeding strategies for inbreeding lines, paternity analysis by SSR (Simple Sequence Repeat) was used to estimate the outcrossing rate and pollen mediated gene flow of M. oleifera . The analysis was carried out in an experimental population domesticated in the dry-hot valley area of Red River with two germplasms (India and Myanmar) of 60 trees, including 12 maternal trees and 60 pollen donors (bisexual flowers, maternal trees were also possible paternal trees in case of selfing). One hundred fifteen seeds out of 288 were confirmed pollen donors by 8 microsatellite loci at 95% strict confidence level. The multilocus outcrossing rate is t m  = 0.797 ± 0.096, and single-locus outcrossing rate is t s  = 0.742 ± 0.058. Pollen dispersal distance varied from 0 m (self-pollination) to 24.7 m, with an average of 11.9 m, and 95% of effective pollen was dispersed within 20 m, indicating that the effective pollen mediated gene flow is restricted to a limited distance. 50.3% of effective pollen was donated by 9 trees. Moreover, there was no apparent correlation between pollen dispersal distance and pollen contribution rate, as well as between germplasm and reproducibility. The maximum pollen dispersal distance between two trees estimated in this experimental stand is highly localized at current 3 × 3 m planting density, indicating that M. oleifera seed orchards and clones could be planted nearer to each other than previously thought (as far as kilometers). [ABSTRACT FROM AUTHOR]

The Beijing–Tianjin Sandstorm Source Region (BTSSR) is the main sandstorm source area in northern China, which plays a crucial role in ecological safety and sustainable development of Beijing and the neighbouring areas. As a result of climate change, ecological restoration and anthropogenic activities, the ecosystem in the BTSSR has experienced substantial changes over the recent decades. The main objective of this study is to quantify the dominant ecosystem services from 2000 to 2010, based upon observations and biophysical models. Furthermore, we investigated the role of climatic variability and ecological restoration program in vegetation activity and ecosystem services. Although the slight increase, both in precipitation and temperature during 2000–2010 and despite the implemented ecological rehabilitation, several drought events offset the ecological rehabilitation program. During 2000–2010, both the overall soil conservation and hydrological regulation functions were slightly enhanced. The carbon sequestration remained stable and food production has sharply increased. The increasing rainfall erosivity has intensified water erosion, whereas the reduction in wind speed weakened wind erosion and thereby reduced the sandstorm events. Vegetation restoration induced by the climatic variability and ecological program has also played a positive role in soil conservation and hydrological regulation enhancement. The spatial correlation analysis indicated the synergies between multiple regulating ecosystem services. Moreover, a synergy between food yield and vegetation carbon sequestration (biomass production) has been identified as well. The experience of ecological rehabilitation and ecosystem change in the BTSSR has exemplified the ecological conservation should take climatic variability into account, and facilitate the synergies on multiple ecosystem services in order to maximize the ecosystem's benefits to human well-being. [ABSTRACT FROM AUTHOR]

Human demands for natural resources have significantly changed the natural landscape and induced ecological degradation and associated ecosystem services. An understanding of the patterns, interactions, and drivers of ecosystem services is essential for the ecosystem management and guiding targeted land use policy-making. The Losses Plateau (LP) provides ecosystem services including the carbon sequestration and soil retention, and exerts tremendous impacts on the midstream and downstream of the Yellow River. Three dominant ecosystem services between 2000 and 2012 within the LP were presented based on multiple source datasets and biophysical models. In addition, paired ecosystem services interactions were quantified using the correlation analysis and constraint line approach. The main conclusions are as follows. It was observed that the warming and wetting climate and ecological program jointly promoted the vegetation growth and carbon sequestration. The increasing precipitation throughout 2000–2012 was related to the soil retention and hydrological regulation fluctuations. The vegetation restoration played a positive role in the soil retention enhancement, thus substantially reduced water and sediment yields. The relationships between ecosystem services were not only correlations (tradeoffs or synergies), but rather constraint effects. The constraint effects between the three paired ecosystem services could be classified as the negative convex (carbon sequestration vs. hydrological regulation) and hump-shaped (soil retention vs. carbon sequestration and soil retention vs. hydrological regulation), and the coefficients of determination for the entire LP were 0.78, 0.84, and 0.65, respectively. In the LP, the rainfall (water availability) was the key constraint factor that affected the relationships between the paired ecosystem services. The spatially explicit mapping of ecosystem services and interaction analyses utilizing constraint line approach enriched the understanding of connections between ecosystem services and the potential drivers, which had important implications for the land use planning and landscapes services optimizing. [ABSTRACT FROM AUTHOR]

Restoring disturbed and over-exploited ecosystems is an important part of mitigating human pressures on natural ecosystems. An ambitious ecological restoration program, the Grain for Green Program (GFGP), was launched in 1999 in China. We selected the Loess Plateau (LP) as a case study, and evaluated ecosystem changes between 2000 and 2012 using biophysical models, observation records, and literature data. It was observed that both the warming and wetting of climate and the ecological program promoted vegetation growth and biomass production (i.e., carbon sequestration). Overall ecosystem patterns were relatively stable; grassland, residential land, and forest increased in area, while farmland area decreased slightly. Increasing precipitation throughout the study period was related to fluctuations in soil retention and hydrological regulation. Vegetation restoration induced by climate variability and the ecological program played a significant role in soil retention enhancement, which also substantially reduced sediment load. The land-use conversion in ecological restoration program promoted soil carbon sequestration, but featured differences in conversion types and rainfall zones. The ecosystem changes recorded in the LP, which resulted from both the ecological program and climate variability, might be temporary improvements rather than fundamental ecosystem shifts. The success of this ecological restoration in the LP exemplifies the positive effects of environmental policies and the necessity of adopting an adaptive management approach. However, the current assessment was not comprehensive, as it involved only three dominant regulating services, and there were still trade-offs among multiple ecosystem services. Therefore, a deeper understanding of the interactions and trade-offs among ecosystem services is required to explore in the context of emerging climate change, so as to support environmental management that maximizes ecosystem benefits to human well-being. [ABSTRACT FROM AUTHOR]

The temperature distribution and vanadium flow rate distribution in the vanadium redox flow battery are the key to its performance. The reaction process in the vanadium redox flow battery is very complex, in the course of power generation, the uniformity and expendability of vanadium liquid distribution will result in nonuniform temperature distribution. Local high temperature will accelerate the ions through the membrane material, the vanadium electrolyte concentration decreases obviously, so that the overall generating efficiency of vanadium redox flow battery is influenced. On the other hand, under the limitation of low flow rate, the waste heat generated by vanadium redox flow battery is unlikely to be carried away by the flow field, so that the internal temperature of vanadium redox flow battery rises. On the contrary, in the condition of high flow rate, the waste heat in the vanadium redox flow battery dissipates rapidly, the temperature is low, the vanadium redox flow battery efficiency is increased slightly, proving that the flow control is also important to the vanadium redox flow battery performance. However, the authentic information inside the vanadium redox flow battery cannot be obtained accurately and instantly by outside, theory and simulation at the present stage. Therefore, according to the requirement for technical application of internal real-time microscopic diagnosis to vanadium redox flow battery, this study proposes using micro-electro-mechanical systems technology to develop a flexible integrated (temperature and flow) microsensor embedded in the vanadium redox flow battery for real-time measurement. The advantages of this technology include: (1) compactness; (2) flexible measurement position and accurate embedding and (3) accurate measurement, high sensitivity and quick response. [ABSTRACT FROM AUTHOR]

Pile foundations are always subjected to cyclic loads due to the action of wind and waves. A cyclic p-y curve model considering the characteristic of friction force is proposed to study the lateral response of pile foundations under unidirectional cyclic loads in sand. The soil resistance calculated by the improved nonlinear strain wedge model (SWM) is divided into friction resistance and compression resistance according to the different characteristics of soil resistance. The friction resistance depends on the relative displacement between pile and soil, whose direction and magnitude will constantly change in the process of cyclic load, while the compression resistance is analyzed by combining the extended Masing rule and soil degradation model. The validity of the model proposed in saturated sand is verified by centrifuge test results. Furthermore, the influence of cyclic loads on pile deflection, bending moment and soil resistance is analyzed through the results calculated by the cyclic p-y curve model. • A cyclic p-y curve model considering the characteristic of friction is proposed to study the cyclic lateral response of pile. • The friction is related to the relative displacement between pile and soil, whose direction reverses periodically. • The soil resistance is divided into compression resistance and friction resistance to established the cyclic p-y curve model. [ABSTRACT FROM AUTHOR]

A load transfer model for vertically loaded bored piles in sea reclamation areas with gravel is proposed in this paper. The focus is on quantifying the mobilization of pile-side friction, which is closely related to the shear behaviors of the pile-gravel interface. The surface profile of the gravel particles and the concrete piles are assumed to be circle and wave curves, respectively. The shear displacement and dilatancy calculation are based on the macro and micro geometry relationship between gravel particles and pile surface. The shear stress calculation of the pile-gravel interface is dealt with by empirical elastoplastic equations. A simple slip-line field is also built to identify the critical shear displacement. The finite difference equations are used to derive the load-displacement curves for vertically loaded bored piles in sea reclamation areas with gravel. The model predictions are compared with field observations and particle flow numerical simulation to validate the performance of the proposed method, and the results prove to be reasonable. Moreover, parameter studies are conducted and the results prove that the pile can bear more load when the particle diameter is similar to the pile's rough surface, and both the increases of wave angle and the relative friction coefficient can promote the bearing capacity. • A load transfer model for vertical loaded bored piles in sea reclamation areas with gravel is proposed in this paper, which is closely related to shear behaviors of the pile-gravel interface. • The shear displacement and dilatancy calculation are based on the macro and micro geometry relationship between gravel particles and pile surface. The shear stress calculation is dealt with empirical elasto-plastic equations. • A simple slip-line field is built to identify the critical shear displacement. The finite difference equations are used to derive the load-displacement curves for vertical loaded bored piles in sea reclamation areas with gravel. [ABSTRACT FROM AUTHOR]

The changes of water and sediment discharges in the headwaters of large Asian rivers have increasingly become a hot issue. This study investigated the streamflow and sediment discharge changes in the headwaters of Yellow River Basin (YRB) and Yangtze River Basin (YARB) by using long-term hydro-meteorological data from 1956 to 2012. The nonparametric Mann–Kendall test, Pettitt test, cumulative anomaly curve (CAC), and double cumulative curve (DCC) were used to identify trends and change points of the hydro-meteorological variables and quantify the response of streamflow and sediment discharge to climate change and anthropogenic activities. The results are as follows. (1) Slightly decreasing trend in streamflow and increasing trend in sediment discharge were detected from 1956 to 2012 in the headwater of YRB. Meanwhile, both streamflow and sediment discharge in the headwater of YARB showed increasing trend. Change-point analyses further revealed that turning (transition) years existed and the abrupt decline in streamflow and sediment discharge began in 1989. (2) The specific sediment yield–runoff depth and sediment concentration–streamflow relationships in the two basins could be well fitted by the power function on the annual, flood season, and monthly scales. Sediment productive ability of runoff during the flood season was much greater than that over the full year. (3) The headwater of YRB contributed huge amount of water resources and very little sediment to the downstream, however, the headwater of YARB had little influence on downstream. (4) Compared with the baseline period (1956–1989), precipitation reduction played a major role in the streamflow and sediment discharge reductions in the post-baseline period (1990–2012). Given the scarcity of soil and water resources, anthropogenic and climatic impacts on streamflow and sediment discharge must be given more attention in the future. [ABSTRACT FROM AUTHOR]

This paper proposes an analytical method for laterally loaded piles in sand, in which the strain wedge model and failure wedge model are used together. To determine the process that develops from the strain wedge model to the failure wedge model, a 3D finite element analysis is carried out. Considering the continuity of the soil resistance, the relationship between the strain wedge model and failure wedge model is established. Two failure patterns in which the soil develops from the strain wedge model to the failure wedge model are discussed. The lateral response of the pile and soil is obtained by an iterative calculation. Two centrifuge tests are used to evaluate the accuracy of the new method, showing remarkable agreement. [ABSTRACT FROM AUTHOR]

The Loess Plateau (LP) is one of the most fragile eco-regions in China, and is characterized by severe soil erosion and water shortage. The fragile environment poses a threat to ecological safety and sustainable development on the LP and neighboring areas. The ecosystem on the LP has undergone great changes in recent decades owing to dramatic climate change, ecological rehabilitation, and tremendous human pressure. This study was focused on quantifying and assessing the multiple ecosystem services from 2000 to 2012, based on actual observation records and widely used biophysical models. These included Universal Soil Loss Equation (USLE), Revised Wind Erosion Equation (RWSQ), Carnegie-Ames-Stanford Approach (CASA), and rainfall storage method. Furthermore, in this study, the roles of climate variability and an ecological restoration program on vegetation activity and ecosystem services were investigated, as well as the synergies between multiple ecosystem services. The slight increase in both precipitation and temperature during 2000–2012, in conjunction with ecological rehabilitation, induced a trend of increasing in vegetation cover and productivity. During 2000–2012, the overall soil retention function was slightly enhanced while the amount of hydrological regulation decreased. The biomass production (vegetation carbon sequestration) and food production increased sharply. The increasing precipitation intensified water erosion by enhancing rainfall erosivity, whereas the reduction in wind speed lessened wind erosion and thereby reduced the frequency and duration of sandstorm events. Vegetation restoration supported by climate variability and resulting from ecological projects also played positive roles in soil retention enhancement. The spatial correlation analyses indicated synergies between multiple regulating ecosystem services. There was also a synergy between food production and carbon sequestration in vegetation. The performance of ecological rehabilitation and changes in ecosystem services on the LP exemplified the need for ecological conservation to take climate variability into account, and to facilitate synergies involving multiple ecosystem services, to maximize human well-being and preserve natural ecosystems. [ABSTRACT FROM AUTHOR]

Under the impacts of climate change and human activities, violent fluctuations of streamflow are observed in large river basins in China. Therefore, comparative assessment of the climatic and anthropogenic influence is crucial for better water resources planning and management. This study investigates the streamflow change in the Liao River Basin (LRB), one of the largest basins in northeast China, using long-term hydrological and meteorological data for the period of 1953–2011. The nonparametric Mann–Kendall test, Pettitt test, and cumulative anomaly curve are used to identify trends and change points of the hydro-meteorological variables. In the past 59 years, the annual and seasonal mean streamflow exhibited significant downward trend. The monthly mean streamflow presented upward trends in January, February, and May, while a downward trend was observed in other seasons. Turning points in the streamflow occurred in the years 1964, 1984, and 1998, which divide the long-term runoff series into a natural (baseline) and three human-induced periods. The high ( Q 5 ), low ( Q 95 ), and median ( Q 50 ) flow during the natural period (1953–1964) was higher than that in two human-induced periods (1965–1984 and 1999–2011). The hydrologic sensitivity method was employed to evaluate the effects of climate change and human activities on the annual runoff during the human-induced periods. The results revealed that anthropogenic influence had a far greater contribution (> 56.6%) to the streamflow variability than that by climate change (< 43.4%). Thus, human activities are considered as the most important factor controlling streamflow changes in the LRB. [ABSTRACT FROM AUTHOR]

The nonlinear response of horizontally loaded piles located at the crest of offshore cohesionless soil slope is analyzed, based on the failure wedge model (FW) with variational base angle, in this study. The pile deflection differential equation considering the three-dimensional friction effect is derived; the failure wedge model with the variational base angle on slope crest is proposed; the three-dimensional friction effect along the pile on the failure wedge is considered; the calculation formula for ultimate soil resistance around pile on cohesionless soil slope crest is derived. The feasibility of the proposed method is proved by comparing the theoretical results with the test results. Finally, the slope effect and friction effect along the pile on laterally loaded pile behavior and the influence of pile diameter on the friction effect are analyzed and discussed based on the proposed method. Slope can weaken the soil resistance around the pile, while friction can strengthen that around the pile. The friction effect gets more significant with the increase of pile diameter. • The pile deflection differential equation considering three-dimensional friction effect is derived; the failure wedge model with variational base angle on slope crest is proposed; the three-dimensional friction effect along the pile on the failure wedge is considered. • The nonlinear response of horizontally loaded piles located at the crest of offshore cohesionless soil slope is analyzed with the proposed method. • The slope effect and friction effect along the pile on laterally loaded pile behavior and the influence of pile diameter on the friction effect are analyzed. [ABSTRACT FROM AUTHOR]

A new p–y curve of the lateral static loading of large diameter piles in cohesive slopes is proposed in this paper, which considers both the size effect and slope inclination. A series of pile size and slope inclination varied three–dimensional finite difference analyses are used to study the behavior of large–diameter pile foundations under lateral loading on cohesive sloping ground. Based on the results of numerical calculations, the pile–soil failure mechanism is discussed for large–diameter piles. Combined with the failure mechanism, nonlinear analytical formulations are derived for the ultimate lateral load and initial stiffness of hyperbolic p–y curves at different depths, which considers both the size effect and slope inclination. The proposed p–y curve is compiled into a program for parametric analysis of pile displacement and bending moment. To verify the proposed p–y curve, it is compared with large–scale foundation lateral loading field test and centrifuge test data to obtain a remarkable result. [ABSTRACT FROM AUTHOR]