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Graph Choking Flow Characteristics of the Rectangular Slot-Type Flip Bucket by S. Li, J. Wu, F. Ma Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. [Extracted from the article]

This paper reports the lateral – moment bearing capacity of bucket foundations under lateral loading in sand. The Modified Mohr-Coulomb (MMC) model is adopted to capture the hardening – softening behaviour in medium dense and dense sands within a finite element (FE) modelling framework. The FE model performance is assessed against available field test data as well as analytical solutions showing a relatively good agreement. A series of parametric study is conducted to investigate the effects of bucket aspect ratio, bucket diameter, load eccentricity, vertical load and relative density of sand on the lateral - moment bearing capacity of the bucket. Comparisons are drawn between the conventional Mohr-Coulomb (MC) model and the stress dependent MMC model highlighting the role of sand dilatancy in mobilising the lateral moment capacity. Based on the FE results, a simple stepwise calculation framework is proposed for two scenarios: (i) to predict the lateral - moment bearing capacity of the bucket if the bucket dimensions are known, and (ii) to design the bucket dimensions for a known required bucket capacity. • The modified Mohr-Coulomb (MMC) model is adopted to capture the behaviour of medium dense and dense sands. • The effects of bucket dimension, load eccentricity, vertical load and relative density of sand are investigated. • Based on the FE results, simple stepwise calculation frameworks are proposed for two scenarios. [ABSTRACT FROM AUTHOR]

The drained tension capacity of suction buckets under vertical uplift loading is calculated as the sum of friction on the inside and outside bucket wall without considering the submerged self-weight of suction buckets. When using existing methods to predict the drained tension capacity, it may be convenient to assume that the vertical effective stress along bucket walls at ultimate loading keeps the same as the initial static vertical effective stress. However, during uplift loading, the vertical effective stress was found to be reducing due to the gradually mobilized friction. This paper presents the results of finite element analyses on suction buckets in sand. The analyses focus on the distribution of vertical effective stress in the direction of bucket diameter and along the bucket wall. Compared with the initial vertical effective stress, a pronounced decrease in the vertical effective stress along the inside bucket wall is observed, but the vertical effective stress along the outside bucket wall has a minor change. The interface factor (ratio between friction stress and vertical effective stress) increases with the depth rather than a constant. Based on the numerical results, equations to predict the drained tension capacity are proposed for suction buckets in sand. • The distribution of vertical stress in the direction of bucket diameter and along the bucket wall are investigated. • The interface factor (ratio between friction stress and vertical stress) along the bucket wall is analyzed. • Equations to predict the drained tension capacity are proposed for suction buckets in sand. [ABSTRACT FROM AUTHOR]

The article discusses that KCF Church in Kensington, Johannesburg, runs a hamper project every month, where church distributed 400 buckets of food to people in need.

It imagines that the total quantity could be contained in 100 buckets, and states that (i) about 95 of those buckets contain sea water, and (ii) about two buckets are filled from ice from glaciers and polar regions. ( I This topic was kindly suggested by Professors Andreas Muller and Cedric Loretan. i ) Question 1: Estimate by how much the sea level will rise from the melting of glaciers and polar regions. Graph: f1 The following information is taken from a science literacy test[1] concerning the distribution of water in different places (e.g., glaciers and oceans). [Extracted from the article]

Tripod suction bucket foundations are increasingly used to support offshore wind turbines (OWTs) due to their economic advantages and high overturning resistance. In the harsh marine environment, OWT tripod bucket foundations are subjected to long-term lateral cyclic loads from wind, waves and current. However, the response of tripod bucket foundations in clay to cyclic lateral loads is not well covered in the literature. Therefore, a three-dimensional (3D) numerical method is developed for analyzing their lateral cyclic response based on a simplified bounding surface model of clay. The numerical model is validated by comparing its results with scaled model test results available in the literature. The validated model is then used to investigate the rotation mechanism of tripod suction bucket under lateral monotonic and cyclic loading. The 'bonded contact' and 'separable contact' were set between the soil plug and the inner wall to simulate the upper limit and the lower limit cases of the tensile capacity of the suction bucket. The influences of the bucket-soil contact condition, loading direction and cyclic loading mode (one-way and two-way) on the cyclic behavior were analyzed. It was found that these factors have a significant impact on the cyclic responses, permanent rotation angle and failure mechanism of the tripod bucket foundation. The findings from this study can provide guidance for the design of OWT tripod bucket foundations. • A numerical method is developed to simulate lateral cyclic response of tripod suction bucket in clays. • Rotation mechanism of tripod suction bucket in clays subjected to lateral monotonic and cyclic loads is investigated. • The influence of bucket-soil contact condition on monotonic and cyclic behaviors of tripod suction bucket is investigated. • The influence of the loading direction and loading modes on the cyclic behavior of tripod suction bucket is investigated. [ABSTRACT FROM AUTHOR]

The tripod bucket foundation that combines three single buckets within a triangular shape, is an emerging alternative foundation solution to support offshore wind turbine in deep water. Its performance of geotechnical capacity, especially under overturning loading, is increasingly concerned by offshore engineering. This paper reports an investigation to anti-overturning capacity of tripod bucket foundations in clay, with focus on the relatively larger foundation embedment. The kinematic mechanisms of the whole foundation system are systematically examined against increasing foundation spacing, considering the influence of foundation embedment. Based on these, an efficient method to predict the anti-overturning capacity is proposed, covering a wide range of embedment, spacing and soil strength heterogeneity. Finally, some recommendations of optimization for sizing foundation are offered, with the example application demonstrated. 1. The evolution of failure mechanisms of tripod bucket foundations in clay against foundation spacing at different embedment is investigated under overturning loading, with global failure, transient failure and separate local failure modes identified. 2. The pull-push combined with rotational failure mechanism can be mobilised under high spacing ratio, with the contribution from rotational failure mechanism to anti-overturning capacity occupying around 12.6%–30%. 3. A method is developed to estimate the anti-overturning capacity of tripod bucket foundation in clay, with some practical considerations and recommendations of optimizing foundation design provided. [ABSTRACT FROM AUTHOR]

Wave run-up around foundations is a hot research topic in offshore wind engineering, particularly for novel composite bucket foundations (CBFs). This study investigates wave run-up on a CBF due to random waves via physical model experiments. The variation in wave run-up around a CBF and the influence of relative wave height on the maximum relative wave run-up is analysed. The experimental results show that the maximum relative wave run-up is found at the 0° marking, and the lowest wave run-up heights occur between the 108° and 144° markings. Moreover, the velocity stagnation head theory (VSH theory) and M5ʹ model tree are employed to predict the wave run-up and obtain an optimum prediction model. Statistical indicators, including the coefficient of determination, agreement index, scatter index, and bias, were used to evaluate the performance of the generated formulae. The prediction formula developed by the VSH theory combined with the second-order Stokes wave theory based on the particle velocity at the mean free surface has good performance in the prediction of wave run-up on the CBF due to random waves. The performance of the formula for relative wave run-up was developed using the M5ʹ model tree based on the scatter parameter, relative wave height, and wave steepness and was optimal according to statistical indicators. The relative wave height plays a crucial role in wave run-up prediction. The relative wave run-up height increases with an increase in the scatter parameter, relative wave height, and decrease in wave steepness. These two methods are recommended for predicting wave run-up on CBF owing to random waves. • Small-scale model tests were performed to investigate wave run-up on the composite bucket foundation (CBF) in the wave flume. • The variation of wave run-up around a CBF and the influence of wave parameters on maximum relative wave run-up was analysed. • The velocity stagnation head theory (VSH theory) and M5ʹ model tree algorithm are applied to predict wave run-up on a CBF. [ABSTRACT FROM AUTHOR]

• Based on the suction penetration test of bucket foundation, the distribution regularity of the excess porewater pressure of soil and soil pressure on both sides of bucket wall and bucket end are revealed. • Based on finite element method, the seepage characteristics of the bucket foundation during the penetration process are analyzed, and the change regularity of the effective stress and resistance of soil during the penetration process of bucket foundation is obtained. • Considering the effect of effective stress on seepage, a calculation method for required suction of bucket foundation with few easy-obtained parameters is established. The accurate estimation of penetration resistance of the bucket foundation is the key step for its installation, and the core part of the estimation of the penetration resistance is the exact prediction of the drag reduction effect due to suction. Therefore, in the present paper, the change regularity of the excess porewater pressure along the bucket wall and at the tip is analyzed by combining the model test and finite element analysis method, along with the soil pressure of the bucket foundation during the suction penetration process in sand. The results showed that, during the suction penetration process of the bucket foundation, the soil pressure and excess porewater pressure change approximately linearly with the depth of the bucket wall, and the reduction degree of lateral resistance due to seepage increases in a power function growth trend. Based on the effective stress principle of soil and basic theory of seepage and considering the effect of seepage on penetration resistance, the change regularity of the effective stress of soil along the bucket wall during the penetration process is obtained. Besides, the calculation method for penetration resistance and required suction of bucket foundation in sand soil is established, and the effectiveness of the present method is verified by comparing with the model test and engineering case, which can provide theoretical basis for engineering design and construction of bucket foundation. [ABSTRACT FROM AUTHOR]

A series of 1 g experimental tests was conducted to investigate the effect of drainage condition on the pullout characteristics of bucket foundations in sand. Model buckets with a constant diameter of 150 mm and length-to-diameter ratios of 1.5, 1.0 and 0.5 were employed with pullout rates ranging from 0.05 mm/s to 20 mm/s. The phenomena of heaving, gapping below the lid, and suction pressure have been investigated and discussed. The peak pullout load, peak suction pressure and heave increased with the increase in the pullout rate and L/D. The drainage factor was proposed to classify the drainage conditions during bucket pullout. The drainage factor is a function of the pullout rate and the inflow velocity. The inflow velocity converged to a nearly constant value defined as the critical inflow velocity. The pullout rates beyond the critical inflow velocity induced undrained conditions. The drainage conditions were classified as drained, partially drained, and undrained based on the proposed drainage factor. The drainage factor criterion reasonably classified the drainage conditions induced at peak pullout load. • 1 g experimental tests were conducted on polycarbonate model buckets varying the pullout rates. • The effect of drainage conditions on the pullout characteristics of bucket foundations was investigated. • The peak pullout load, suction pressure and the heave increased as the pullout rate and L/D increased. • Undrained conditions were induced when pullout rates were higher than the critical inflow velocity. • The drainage factor criterion has been proposed to classify the drainage conditions during pullout. [ABSTRACT FROM AUTHOR]

In this study, a series of three-dimensional small-strain analyses are carried out to explore the combined capacity of bucket foundations in soft-over-stiff clay under general loading. It aims to provide a supplement to existing design codes. Numerical models are generated and validated with existing data in open literature, where good agreements are obtained. The effects of the layered deposit are explored, including the thickness of the upper soft clay, the length of skirt, the magnitude of the vertical load, and soil properties. Due to the presence of soft clay, the uniaxial bearing capacities reduce significantly, reaching as low as 25% reduction compared to the caisson in uniform stiff clay. In the V - H, V - M and V - H - M spaces, the failure envelopes are normalized in unique shapes according to the geometry of the bucket. Based on the numerical results, an empirical design procedure is proposed to evaluate the failure envelopes of bucket foundations subjected to complex loading conditions in soft-over-stiff clay. [ABSTRACT FROM AUTHOR]