Cyclic Behavior of Calcareous Sand from the South China Sea

Liu, Lu; Yao, Xiaofei; Ji, Zhanpeng; Gao, Hongmei; Wang, Zhihua; Shen, Zhifu

doi:10.3390/jmse9091014

Cited by 14 publications

(3 citation statements)

References 27 publications

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“…Calcareous sand, abundant in the South China Sea and originating from marine organisms like corals and shells, mainly consists of insoluble carbonates, particularly calcium carbonate [1][2][3]. Its extensive utilization as a construction filler in island development encompasses a variety of applications, including foundations [4], roadbeds [5], and airport runways [6].…”

Section: Introductionmentioning

confidence: 99%

Investigation on the Confined Breakage Characteristics of Calcareous Sand in the South China Sea Integrated Using Relative Breakage Ratio and Fractal Dimension

Zhu,

Zheng,

Yang

2024

Sustainability

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Calcareous sand, ubiquitous in the geotechnical makeup of the South China Sea, exhibits both compressibility and vulnerability to fragmentation when subjected to external loading, spanning a spectrum from typical to extreme conditions. This investigation aims to quantitatively assess the compression and particle breakage characteristics of calcareous sand under varied parameters, including relative density, saturation, applied loads, and loading paths, specifically focusing on sustainable geotechnical methodologies. Through a series of confined compression tests, this evaluation employed the relative breakage ratio and fractal dimension as key evaluative metrics. The results indicated that employing this integrated approach offered a more comprehensive understanding of calcareous sand breakdown mechanisms than relying on a singular particle breakage index. Furthermore, an increase in relative density can induce a transition in particle contact behavior, shifting from point-to-point interactions to face-to-face contact, thereby reducing inter-particle stress and minimizing grain breakage, particularly under loads below 200 kPa. Increasing loads exacerbated particle breakage, with finer particles predominantly initiating this process. During reloading, pore ratios across various load levels surpass those observed during initial loading, except at 1600 kPa, where a decline in pore ratio was noted, coinciding with pore water extrusion and the onset of new particle fracturing. The lubricating effect of water reduces inter-particle friction, enhancing stress concentration at particle edges and localized particle breakage, thereby increasing the presence of finer particles without significantly altering the overall structure. Notably, the influence of pore water pressure is evident during the reloading phase. These findings contribute to a refined theoretical framework for predicting coastal erosion risks and devising effective environmental protection strategies for sustainable coastal engineering practices.

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Section: Introductionmentioning

confidence: 99%

Investigation on the Confined Breakage Characteristics of Calcareous Sand in the South China Sea Integrated Using Relative Breakage Ratio and Fractal Dimension

Zhu,

Zheng,

Yang

2024

Sustainability

View full text Add to dashboard Cite

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“…He et al [9] investigated the resilient modulus response of coral sand from the South China Sea under cyclic loading and established a new prediction model to predict the resilient modulus of coral sand in the whole stress interval. Liu et al [10] investigated the cyclic behavior of calcareous sand from the South China Sea through a series of undrained cyclic triaxial tests and found that cyclic stress ratios and relative density had a notable effect on the cyclic behavior of calcareous sand, which had higher liquefaction resistance than silica sand due to its angular nature. Ma et al [11] presented the results of a multi-stage strain-controlled undrained cyclic shear test on saturated coral sand and proposed a new index to modify the prediction model of the maximum shear modulus and reference shear strain under different consolidation conditions, which shows an excellent prediction of shear modulus with a deviation within ±10%.…”

Section: Introductionmentioning

confidence: 99%

Influence of Topographic and Geological Features on the Seismic Response of the Reef Site in the South China Sea

Bao

Liu

Wang

2023

JMSE

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Insufficient comprehension of the seismic impact of the reef terrain, geology, and material properties of the reefs in the South China Sea still presents considerable impediments in studying the seismic response of reef engineering sites and assessing their seismic safety. To surmount this challenge, a seismic response analysis model of the reef-seawater system is established. This model takes into account the fluid-solid interaction effect, the wave radiation effect of the infinite seawater layer and the semi-infinite seabed, as well as the seismic wave input process of the reef-seawater system. Through targeted parameter analyses, the impact of various factors, including the shear wave velocity, thickness, and slope of distinct reef layers, the width of the reef flat, and the dynamic coupling effect of seawater on the seismic response of reef sites, is thoroughly examined. It has been determined that the seismic response of the reef site is markedly amplified as the shear wave velocity decreases and the thickness of the uppermost reef layer increases. While the effects of the slope gradient of the topmost reef layer and the width of the reef flat on the seismic response of the reef site are chiefly observed in the edge area and the central area, respectively. The layer of seawater plays a crucial role in radiation damping, serving as a medium for the dissipation of seismic energy and thereby weakening the overall seismic response of the reef site.

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“…The promotion of the Hainan free trade port policy has attracted the attention of the state toward the construction and development of the South China Sea islands and reefs. Calcareous sand, which is widely distributed in the South China Sea, is mainly composed of coral debris, submarine limestone, and marine biological debris with a CaCO 3 content of more than 50% [1,2]. Calcareous sand is not conducive to direct application in engineering because of the irregular shape, large porosity, low bearing capacity, and fragile engineering characteristics of the sand particles [3,4].…”

Section: Introductionmentioning

confidence: 99%

Experimental Study of MICP-Solidified Calcareous Sand Based on Ambient Temperature Variation in the South China Sea

Yang

Zhou

et al. 2023

Sustainability

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With the continuous advancement of the construction of the Hainan Free Trade Port and Island Reef Project, deploying Microbial Induced Calcium Carbonate Precipitation (MICP technology) for related research on the temperature range in this area would be of great significance. MICP technology is an innovative and sustainable new soil reinforcement technology that uses the metabolic activity of specific bacteria to produce calcium carbonate precipitation (CaCO3) to connect loose soil. A few previous studies reporting on the applications of MICP technology in different temperature environments drew different conclusions. Therefore, this study involved MICP sand column reinforcement tests at ambient temperatures of 20 °C, room temperature, 30 °C, and 40 °C. The reinforcement effect was evaluated using indicators such as CaCO3 generation rate, Ca2+ conversion rate, bacterial adhesion rate, water absorption rate, and unconfined compressive strength, providing a reference basis for the future applications of MICP technology to island and reef engineering construction. The results showed that, with an increase of temperature from 20 °C to 40 °C, the CaCO3 production rate, Ca2+ conversion rate, and unconfined compressive strength showed a trend of first increasing and then decreasing; the UCS was 548 KPa at 20 °C and 2276.67 KPa at 30 °C; the water absorption rate at 20 °C was 25.32, which decreased continuously with increasing temperature, and reached 21.49 at 40 °C; and the bacterial adhesion rate also continued to rise in the range of 20 °C to 40 °C, from 10.91 to 28.44. The increase in temperature had an impact on the physiological state of bacterial cells. A scanning electron microscope test shows that CaCO3 crystal forms generated under different temperature environments were different, and the CaCO3 mineral deposits generated during MICP reinforcement at 30 °C were denser. Fewer gaps were present between adjacent sand particles, and the bond was tight, which served better as a bridge. The strength of the solidified sample was also higher. The annual average temperature of the South China Sea is about 30 °C. The findings of this experiment provide feasibility and sustainable development for MICP project reinforcement in the South China Sea.

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Cyclic Behavior of Calcareous Sand from the South China Sea

Cited by 14 publications

References 27 publications

Investigation on the Confined Breakage Characteristics of Calcareous Sand in the South China Sea Integrated Using Relative Breakage Ratio and Fractal Dimension

Investigation on the Confined Breakage Characteristics of Calcareous Sand in the South China Sea Integrated Using Relative Breakage Ratio and Fractal Dimension

Influence of Topographic and Geological Features on the Seismic Response of the Reef Site in the South China Sea

Experimental Study of MICP-Solidified Calcareous Sand Based on Ambient Temperature Variation in the South China Sea

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