Seismic Fragility Assessment of a Novel Suction Bucket Foundation for Offshore Wind Turbine under Scour Condition

This study proposed a new suction bucket (SB) foundation model for offshore wind turbines (OWT) suitable for a shallow muddy seabed, using more than three single buckets through kinetic derivation. The performance of new optimal foundation was evaluated by its horizontal displacement capacity and compared with a conventional SB composed of three buckets. Under external loads such as earthquakes, wind, and the combination of the both, the stability of this novel SB foundation was verified. The seismic fragility curve was also evaluated at some scour depths. These results were compared with the response of a tripod suction bucket (TSB) foundation, which was also designed for a shallow muddy seabed. The results indicated that scour significantly changed the dynamic response of this novel SB foundation but it had a better bearing capacity than the TSB foundation, despite its smaller size and weight. The fragility of TSB is always higher than the developed foundation in the same environmental condition. With reasonable volume and size, this novel SB foundation has great potential for future industrialization and commercialization.

The Impact of Using Different Types of Soft Soils Treated by Stone Columns on Creep Behavior

The stone column technique is an effective method to increase the strength of soft cohesive soil, which results in a reduction in foundation settlement and an increase in bearing capacity. The topic of restraining creep settlement through the use of stone columns techniques has gained increasing attention and consideration; because stone columns are widely used to treat soft soil deposits, caution should be applied in estimating creep settlement. We discovered a reversible relation between shear parameters and the creep settlement in floating stone columns; while, in case of end-bearing stone columns shows a direct positive relation between shear parameters and the creep settlement, and the creep settlement began at the primary settlement. The shear parameters affected the improvement factor (n) of creep settlement in both floating and end-bearing stone columns. The standard creep coefficient’s n values in floating and end-bearing conditions were more significant than the low creep coefficient’s n values in forwarded geometric conditions. The stress in both floating and end-bearing stone columns was increasing and uniformly distributed along the length of the floating stone column and in the case of end-bearing stone column was limited to the stiffness layer; the maximum vertical stress was in the central point of the embankment. The embankment’s maximum horizontal displacement occurred on the edge.

The effect of score types on total score in trampoline gymnastics: Example of the European Championship in Sochi 2021

Background and Study Aim. Trampoline gymnastics has a versatile scoring system that has evolved and become more complex over the years. This study aimed to find the effect of the difficulty (D), execution (E), time of flight (TOF), and horizontal displacement (HD) scores on the total score in male and female trampoline gymnasts. Material and Methods. The results of the first round in the qualification round in the individual senior category of the 27th European Championships in Trampoline Gymnastics were used for evaluation. Multiple regression analysis (the enter method) was performed to build a model between the total score and D, E, TOF, and HD scores. Results. According to multiple regression analyses, respectively E, TOF, D, and HD scores were predictors of the total score in the men’s first routine, and D, E, TOF, and HD in the men’s second routine (p<0.05). Although women have the same ranking as the men of the second routines, respectively E, D, TOF, and HD scores were predictors of the first routine (p<0.05). Conclusions. The results show that the E score is critical for the first routines and the D score is critical for the second routines. The fact that the first and second routines were constructed with different strategies as per the competition rules may have caused this result. By reminding coaches and athletes of the fact that the types of scores can affect each other, it can be suggested that they adjust their target scores according to the type of routine and the stage and type of competition.

Full-Scale Field Test On Retaining Structure Enhanced With Soil Nails And Prestressed Anchors

Retaining structure enhanced with soil nails and prestressed anchors is found good at constraining the horizontal displacement and therefore ensuring the stability of the foundation pit during excavation. Based on these advantages, such retaining structure is widely used in foundation excavation practice. This paper presents results of a series of in-situ tests conducted to investigate the mechanical behaviors of retaining structure enhanced with soil nails and prestressed anchors. Behaviors of three different retaining structures enhanced with i) soil-nails; ii) soil-nails and prestressed anchors without unbonded part; iii) soil-nails and prestressed anchors with a 2.5m unbonded length, were monitored during staged excavation to investigate the influences of i) the prestressing force and ii) unbonded length of the prestressed anchors on the performance of the entire retaining system. It was found that the affecting the stress and deformation of composite retaining system, which is in agreement with the other published results in the literature. The variation of the magnitude and distribution of soil nail force responding to the anchor prestressing force however showed no systematic trend. The unbonded length of anchors, which is suggested to be the main factor affecting the structural stability in dense materials in the literature, is found to have little influence in loose fill materials used in this study. Studies presented in this paper are useful for the rational design and serviceability analysis of the composite soil-nailed retaining structure enhanced with prestressed anchors.

Reinforced concrete beams on yielding supports with thrust under dynamic load

Reinforced concrete beam with limited horizontal displacement on yielding supports under dynamic loading require considering the thrust response. The thrust presence significantly increases the beam strength and crack resistance. The use of yielding supports increases their energy intensity. The purpose of the paper is the experimental study of using yielding supports under the dynamic load conditions. The experimental results concern the reinforced concrete beam with yielding supports with a thrust under the dynamic load. The paper shows the effect from yielding supports on the strength, deformability, and crack resistance of reinforced concrete beams. The obtained results indicate to a positive effect form the use of yielding supports of the beam under the dynamic load.

Comment on ‘Unveiling ductile deformation during fast exhumation of a granitic pluton in a transfer zone’ by Richard Spiess, Antonio Langone, Alfredo Caggianelli, Finlay M. Stuart, Martina Zucchi, Caterina Bianco, Andrea Brogi, & Domenico Liotta

In their paper, Spiess et al. (2021) published structural, geochronological, and EBSD data on one of the monzogranite apophyses (Capo Bianco) of the buried Porto Azzurro Pluton (island of Elba, Northern Apennines, Italy), a pluton emplaced in the upper crust (P < 0.2 GPa; e.g. Papeschi et al., 2019). The authors publish a new U/Pb age of 6.4 ± 0.4 Ma, associated to the thermal peak, and a U-Th/He apatite age of 5.0 ± 0.6 Ma, related to a T of 60 °C. Spiess et al. (2021) use these ages to model the exhumation of the pluton controlled by the sub-horizontal Zuccale Fault, a fault with 6 km of horizontal displacement (ZF; Keller & Coward, 1996). Their structural dataset from the macro to the microscale and EBSD analyses relies on a small section (about 100 m wide) in the NE part of the Calamita Peninsula. Based on their documentation of (1) vertical dykes in the monzogranite, (2) vertical to low-angle top-to-the-E extensional faults, and (3) later NW-striking oblique faults, they interpret the Porto Azzurro Pluton as emplaced in an extensional to transcurrent tectonic setting, extrapolating their findings to the entire Eastern Elba.

Deformation Characteristic of a Supported Deep Excavation System: A Case Study in Red Sandstone Stratum

A complete case record of a deep foundation pit with pile-anchor retaining structure excavated in red sandstone stratum is presented in this study. The horizontal displacement of pile top, the horizontal displacement at various depths, the axial force of anchor cable, and ground settlement during construction are measured. A three-dimensional numerical model is established to analyze the additional stress and deformation induced by the excavation and the accuracy of the FEM model is verified by comparing with field measured results. Both the measured and numerical simulation results show that the deformation of the pile-anchor supported deep excavation is significantly affected by the spatial effect. The results show that the deformation in the middle of the foundation pit is greater than the pit angle and that the deformation of the long side is greater than that of the short side and gradually decreases from the middle to the pit angle. The deformation and stress in the middle of the long side of the foundation pit are the largest, which is the most unfavorable part. With the increase of vertical excavation depth, the spatial effects tend to increase, and the influence scope of spatial effects is about five times the vertical excavation depth in the red sandstone stratum. The ground settlement outside the pit is mainly distributed in a groove shape, and the maximum settlement occurs about 8.5 m away from the pit edge. Finally, parametric studies of reinforcement parameters indicated that 1.5–2.0 times the initial elastic modulus and cohesive force of soil should be used for reinforcement. It is recommended that the ranges for pile diameter, pile spacing, anchor cable prestressing and inclination angle should be selected as 0.8–1.2 m, 1.4–2.0 m, 100–150 kN, and 10°–20°, respectively.

Numerical Simulation of Ultra-Shallow Buried Large-Span Double-Arch Tunnel Excavated under an Expressway

The temporal and spatial effects of a complicated excavation process are vital for an ultra-shallow buried large-span double-arch tunnel excavated under an expressway in service. Numerical simulations are urgent and necessary to understand the effect of the total construction process. Taking Xiamen Haicang tunnel as a research object, the total excavation process of three pilot tunnels and the three-bench reserved core soil method of an ultra-shallow buried large-span double-arch tunnel with a fault fracture zone under an expressway was simulated using software FLAC3D. The deformation of the surface, surrounding rock, underground pipelines, tunnel support structure and partition wall of the three pilot tunnels and the main tunnel was analyzed, and the dangerous areas and time nodes were obtained. When the tunnel was excavated to the fault fracture zone, the deformation of the surface and surrounding rock increased significantly. The rock and soil within 20 m behind the excavation surface of the pilot tunnel were greatly disturbed by the excavation. During the excavation of the main tunnel, the horizontal displacement of the middle partition wall moved slightly towards the main tunnel excavated first. The research results can provide a reference for the construction design of double-arch tunnels.

Experimental Study and Numerical Analysis on Impact Resistance of Civil Air Defense Engineering Shear Wall

In order to study the impact resistance of civil air defense engineering shear wall, the impact resistance of civil air defense engineering shear wall was studied by combining finite element numerical simulation with pendulum impact test. The effects of impact height, pendulum mass, and impact times on the impact resistance of civil air defense engineering shear walls were analyzed. It was shown that when the impact height increased from 0.4 m to 2.5 m, the failure mode of civil air defense engineering shear wall tended to be local impact failure, and the horizontal displacement in the middle of the wall span increased. The concrete crushing occurred in the impact area of the back of the civil air defense engineering shear wall. The increase in the impact height is a negative factor for the impact resistance of the civil air defense engineering shear wall. With the increase of pendulum weight, the number of concrete horizontal cracks in the back of the civil air defense engineering shear wall increased, while the number of vertical cracks decreased, but the impact surface was destroyed. Through multiple impact tests on the civil air defense engineering shear wall, the civil air defense engineering shear wall had accumulated damage. The longitudinally loaded steel on the back reached the ultimate strength, and there are large cracks at the bottom and even collapses. The increase of impact times has a great influence on the impact resistance of the civil air defense engineering shear wall. Through the analysis of the factors affecting the impact resistance of civil air defense engineering shear wall, it provides guidance for civil air defense engineering shear wall to resist impact load.

The video feedback viewing in novice weightlifters: Total control strategy improves snatch technique during learning

This study aimed at comparing the efficiency of two viewing control strategies, total control versus partial control, in correcting the snatch technique in school-aged boys (10–12 years old). Thirty-nine participants, with 2 months of weightlifting training experience, were divided into three groups: total control, partial control, or a control group. The Kinovea version 0.8.15 software was used to measure the kinematic parameters of the snatch technique before (T0) and after six learning sessions (T1). Following the learning sessions, total control group showed greater improvements for all kinematic parameters compared with the partial control and control group (e.g., the horizontal displacement (i) in the first pull (Δ Dx2: 18.17 ± 26.75%, p < 0.01, d = 0.83), (ii) between the first and the second pulls (Δ DxV: 25.97 ± 18.02%, p < 0.001, d = 1.52) and from the most forward position to the catch position (Δ DxL: 19.98 ± 21.60%, p < 0.01, d = 1.36), while the partial group improved only on the Dx2 (Δ Dx2 = 21.53 ± 20.40%, p < 0.01, d = 0.86). The present results indicate that the intensive use of the interactive features (e.g. pause, play, forward, and backward) and the asked questions during the first learning phase were essential for the improvement of the snatch technique. These findings have potential practical implications for coaching and physical education teaching.