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physical and mechanical properties of Coral Sand in the Nansha Islands

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Marine Science Bulletin 2006年第2期8卷 31-39页

作者：于红兵孙宗勋唐诚中国科学院南海海洋研究所广东广州510301

Coral sand is a unique material developed in the tropical ocean environment, which is mainly composed of coral and other marine organism debris, with the CaCO3 content up to 96 %. It has special physical and mechanical properties due to its composition, structure and sedimentary environment. In this contribution, we discuss its specific gravity, porosity ratio compressibility, crushing, shearing and intensity for coral sand samples from the Nansha islands based on laboratory mechanical tests. Our results show distinct high porosity ratio, high friction angle and low intensity as compared with the quartz sand. We believe that grain crushing is the main factor that influences the deformation and strength of coral sand. Comprehensive study on the physical and mechanical properties of coral sands is significant in providing reliable scientific parameters to construction on coral islet, and thus avoids accidents in construction.

关键词： Nansha Islands coral sand physical and mechanical properties

physical and mechanical properties OF WOOD/MMT INTERCALATION NANOCOMPOSITES

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PHYSICAL AND MECHANICAL PROPERTIES OF WOOD/MMT INTERCALATION...

Influence of cooling speed on the physical and mechanical properties of granite in geothermal-related engineering

作者： Zhao Guangjie, Lu Wenhua College of Material Science and Technology, Beijing Forestry University, Beijing 100083, China Research Institute of Wood Industry, Chinese Academy of Forestry, Beijing 100091 , China Faculty of Wood Science and Decoration Engineering, Southwest Forestry College, Kunming 650224, China

In order to make clear the modifying effect of MMT on wood, the nanocomposites of Chinese fir(Cunninghamia lanceolata) wood and montmorillonite ( MMT) i. e. WMNC was prepared through impregnating with water-soluble PF resin as intermediate, and the hygroscopicity, dimensional stability, longitudinal compressive strength, abrasion resistance, water-leaching resistance and fire resistance of Chinese fir wood, its PF-impreg and its WMNC were measured and compared. Results show that the properties of WMNC were greatly improved. MMT’ s silicate nanolayers can effectively enhance wood physical and mechanical properties.

关键词： Chinese fir wood MMT PF Nano intercalation compounding physical and mechanical properties

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Deep Underground Science and Engineering 2022年第1期1卷 40-57页

作者： Longchuan Deng Xiaozhao Li Yun Wu Fuqing Li Zhen Huang Yukun Ji Chunjiang Zou Zuxi Liu School of Earth Sciences and Engineering Nanjing UniversityNanjingJiangsuChina State Key Laboratory for Geomechanics and Deep Underground Engineering China University of Mining and TechnologyXuzhouJiangsuChina School of Resources and Environment Engineering Jiangxi University of Science and TechnologyGanzhouJiangxiChina Department of Civil Engineering Monash UniversityMelbourneAustralia

In deep-earth engineering,the high earth temperature can significantly affect the rock's mechanical properties,especially when the rock is cooled during the construction ***,whether the cooling speed affects the mechanical and physical properties of rocks is worth to be *** present study explored the influence of the cooling rate on the physical and chemical properties of granite heated at 25–800°*** mechanical and physical properties involved in this study included uniaxial compression strength,peak strain,modulus,P-wave velocity,mass and volume,the change of which could reflect the sensitivity of granite to the cooling *** emission(AE)monitoring,microscopic observation,and X-ray diffraction(XRD)are used to analyze the underlying damage *** is found that more AE signals and large-scale cracks are accounted for based on the b-value method when the specimens are cooled by ***,the microscopic observation by polarized light microscopy indicates that the density,opening degree,and connectivity of the cracks under water cooling mode are higher than that under natural cooling *** addition,the XRD illustrates that there is no obvious change in mineral content and diffraction angle at different temperatures,which confirms that the change of mechanical properties is not related to the chemical *** present conclusion can provide a perspective to assess the damage caused by different cooling methods to hot rocks.

关键词： cooling methods granite high temperature physical and mechanical properties thermal damage

Construction of virtual mulch film model based on discrete element method and simulation of its physical mechanical properties

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International Journal of Agricultural and Biological Engineering 2020年第4期13卷 211-218页

作者： Wensong Guo Can Hu Xiaowei He Long Wang Shulin Hou Xufeng Wang College of mechanical and Electrical Engineering Tarim UniversityAlar 843300XinjiangChina College of Engineering China Agricultural UniversityBeijing 100083China

In China,especially in Xinjiang Region,mulch film remaining in the soil has severely jeopardized the safety of soil *** numerically simulate the residual film-soil-recovery implementation system,a virtual mulch film model with consistent physical and mechanical properties with real mulch film needs to be *** this study,a flexible deformable virtual mulch film model was constructed using YADE software based on the Minkowski Sum principle and the ball-ball force-displacement constitutive rule,as well as the contact failure rule were *** deformation behaviors of cylinders and PFacet elements,such as stretching,bending,and torsion,were *** splicing the basic PFacet elements,a virtual mulch model was *** mechanical model of a virtual mulch film under tension was established and the axial tensile stiffness coefficient kn was determined to be 43.30 N·*** verify the physical and mechanical properties of this virtual mulch film,both real and virtual stretching and tearing tests were *** experimental results showed that:in the process of stretching and tearing of real and virtual films,the properties of morphological features of both are basically identical;however,they clearly differ in *** viscoelastic constitutive model between balls and yield judgment conditions requires further study.

关键词： discrete element method mulching film physical and mechanical properties virtual test

Research on thermal insulation materials properties under HTHP conditions for deep oil and gas reservoir rock ITP-Coring

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Petroleum Science 2024年第4期21卷 2625-2637页

作者： Zhi-Qiang He He-Ping Xie Ling Chen Jian-Ping Yang Bo Yu Zi-Jie Wei Ming-Zhong Gao State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering College of Water Resource and Hydropower Sichuan University Guangdong Provincial Key Laboratory of Deep Earth Sciences and Geothermal Energy Exploitation and Utilization Institute of Deep Earth Sciences and Green Energy College of Civil and Transportation Engineering Shenzhen University School of mechanical Engineering Sichuan University College of Polymer Science and Engineering Sichuan University

Deep oil and gas reservoirs are under high-temperature conditions, but traditional coring methods do not consider temperature-preserved measures and ignore the influence of temperature on rock porosity and permeability, resulting in distorted resource assessments. The development of in situ temperaturepreserved coring(ITP-Coring) technology for deep reservoir rock is urgent, and thermal insulation materials are key. Therefore, hollow glass microsphere/epoxy resin thermal insulation materials(HGM/EP materials) were proposed as thermal insulation materials. The materials properties under coupled hightemperature and high-pressure(HTHP) conditions were tested. The results indicated that high pressures led to HGM destruction and that the materials water absorption significantly increased; additionally,increasing temperature accelerated the process. High temperatures directly caused the thermal conductivity of the materials to increase; additionally, the thermal conduction and convection of water caused by high pressures led to an exponential increase in the thermal conductivity. High temperatures weakened the matrix, and high pressures destroyed the HGM, which resulted in a decrease in the tensile mechanical properties of the materials. The materials entered the high elastic state at 150.C, and the mechanical properties were weakened more obviously, while the pressure led to a significant effect when the water absorption was above 10%. Meanwhile, the tensile strength/strain were 13.62 MPa/1.3%and 6.09 MPa/0.86% at 100.C and 100 MPa, respectively, which meet the application requirements of the self-designed coring device. Finally, K46-f40 and K46-f50 HGM/EP materials were proven to be suitable for ITP-Coring under coupled conditions below 100.C and 100 MPa. To further improve the materials properties, the interface layer and EP matrix should be optimized. The results can provide references for the optimization and engineering application of materials and thus technical su

关键词： Deep oil and gas reservoir rock In situ temperature-preserved coring (ITP-Coring) Hollow glass microsphere/epoxy resin thermal insulation materials (HGM/EP materials) High-temperature and high-pressure (HTHP) physical and mechanical properties

mechanical Behavior of Bamboo,and Its Biomimetic Composites and Structural Members:A Systematic Review

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Journal of Bionic Engineering 2024年第1期21卷 56-73页

作者： Shanyu Han Yuyuan He Hanzhou Ye Xueyong Ren Fuming Chen Kewei Liu Sheldon Q.Shi Ge Wang Institute of Biomaterials for Bamboo and Rattan Resources International Centre for Bamboo and RattanBeijing 100102China Key Laboratory of National Forestry and Grassland Administration/Beijing for Bamboo&Rattan Science and Technology Beijing 100102China National Forestry and Grassland Engineering Technology Center for Wood Resources Recycling College of Materials Science and TechnologyBeijing Forestry UniversityBeijing 100083China International Bamboo and Rattan Organization Beijing 100102China School of Civil Engineering Tsinghua UniversityBeijing 100084China mechanical Engineering Department University of North TexasDentonTX 762077102USA

Bamboo is a typical biological material widely growing in nature with excellent physical and mechanical *** is lightweight with high strength and *** naturally optimized bamboo structure,which has inspired global material scientists and engineers for decades,is significantly important for the bionic design of novel structural materials with ultra-light,ultra-strong,or ultra-tough and comprehensive *** literature on innovative composite materials and structural members inspired by bamboo are reviewed in this paper,and the research progress and prospects in this field are expounded in three ***,the structural characteristics of the bamboo wall layer along the thickness and height directions are described in terms of chemical composition,gradient structure,pore structure,and hollow structure with variable ***,this paper summarizes the research progress on new composite materials and structural components by applying bamboo’s structural features from the perspective of sustainability,designability,and ***,given the limitations of current research,the biomimetic scientific research on bamboo’s structural characteristics is prospected from the interpretation of bamboo structure,new bamboo-like materials,and structural design optimization perspectives,providing a reference for future research on biomimetic aspects of biomass.

关键词： Bamboo Structural characteristics-Bamboo-like material physical and mechanical properties

Critical review of recent development in fiber reinforced adobe bricks for sustainable construction

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Frontiers of Structural and Civil Engineering 2020年第4期14卷 839-854页

作者： Mahgoub MSALIH Adelaja IOSOFERO Mohammed SIMBABI School of Engineering University of AberdeenAberdeen AB243FXUK

This paper presents a state-of-the-art review of research on the utilization of fibers(predominantly derived from waste materials)as reinforcement in adobe brick *** of these wastes provides sustainable construction materials and helps to protect the *** preparation and test procedures are *** effects of addition of these wastes on the physical and mechanical properties of adobe bricks as presented in the literature,are *** main results for each additive are presented and *** is concluded that improved adobe brick properties can be expected with the addition of combination of waste *** use of waste materials in the construction industry is generally of interest and useful for engineers and designers seeking sustainable solutions in *** is also of interest to researchers actively seeking to develop methodical approaches to quantifying,optimising and testing the performance in use of such waste material additives.

关键词： adobe bricks fibre reinforced bricks green sustainable building material physical and mechanical properties

mechanical and acoustic emission characteristics of anhydrite rock under freeze-thaw cycles

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Journal of Mountain Science 2023年第1期20卷 227-241页

作者： ZHANG Chi JIN Xiao-guang HOU Chao HE Jie School of Civil Engineering Chongqing UniversityChongqing400045China China Railway 14TH Bureau Group Fourth Engineering Corporation Limited Jinan250101China Key Laboratory of New Technology for Construction of Cities in Mountain Area of the Ministry of Education Chongqing UniversityChongqing400045China State Key Laboratory of Coal Mine Disaster Dynamics and Control Chongqing UniversityChongqing400045China

To study the damage mechanisms of anhydrite rock under freeze-thaw cycles, the physicalmechanical properties and the microcracking activities of anhydrite rock were investigated through mass variation, nuclear magnetic resonance, scanning electron microscope tests, and uniaxial compression combined with acoustic emission(AE) tests. Results show that with the increase of freeze-thaw processes,the mass, uniaxial compression strength, and elastic modulus of the anhydrite specimens decrease while the porosity and plasticity characteristics *** example, after 120 cycles, the uniaxial compression strength and elastic modulus decrease by 46.54% and 60.16%, and the porosity increase by 75%. Combined with the evolution trend of stressstrain curves and the detected events, three stages were labeled to investigate the AE characteristics in freeze-thaw weathered anhydrite rock. It is found that with the increase of freeze-thaw cycles, the proportions of AE counts in stage Ⅰ and stage Ⅱ show a decaying exponential trend. Contrarily, the proportion of AE counts in stage Ⅲ displays an exponential ascending trend. Meanwhile, as the freeze-thaw cycles increase, the low-frequency AE signals increase while the intermediate-frequency AE signals decrease. After 120 cycles, the proportion of low-frequency AE signals increases by 168.95%, and the proportion of intermediate-frequency AE signals reduces by 81.14%. It is concluded that the microtensile cracking events occupy a dominant position during the loading process. With the increase of freeze-thaw cycles, the b value of samples *** 120 cycles, b value decreases by 27.2%, which means that the proportion of cracking events in rocks with small amplitude decreases. Finally, it is proposed that the freeze-thaw damage mechanism of anhydrite is also characterized by the water chemical softening effect.

关键词： Freeze-thaw cycles Anhydrite rock physical and mechanical properties AE characteristics Damage mechanism

Cement-bonded particleboard with a mixture of wheat straw and poplar wood

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Journal of Forestry Research 2013年第2期24卷 381-390页

作者： Morteza Nazerian Vajiihe Sadeghiipanah Department of Wood and Paper Science and Technology University of Zabol

We investigated the hydration behavior and some physical/mechanical properties of cement-bonded particleboard （CBPB） containing particles of wheat straw and poplar wood at various usage ratios and bonded with Portland cement mixed with different levels of inorganic additives. We determined the setting time and compression strength of cement pastes containing different additives and particles, and studied the effects of these additives and particles on thickness swelling, internal bond strength and modulus of rupture of CBPB by using RSM （Response Surface Methodology）. The mathematical model equations （second-order response functions） were derived to optimize properties of CBPB by computer simulation programming. Predicted values were in agreement with experimental values （R2 values of 0.93, 0.96 and 0.96 for TS, IB and MOR, respectively）. RSM can be efficiently applied to model panel properties. The variables can affect the properties of panels. The cement composites with bending strength 〉 12.5 MPa and internal bond strength 〉 0.28 MPa can be made by using wheat straw as a reinforcing material. Straw particle usage up to 11.5% in the mixture satisfies the minimum requirements of International Standard, EN 312 （2003） for IB and MOR. The dose of 4.95% calcium chloride, by weight of cement, can improve mechanical properties of the panels at the minimum requirement of EN 312. By increasing straw content from 0 to 30%, TS was reduced by increasing straw particle usage up to 1.5% and with 5.54% calcium chloride in the mixture, TS satisfied the EN 312 standard.

关键词： cement-bonded particleboard wheat straw poplar additives setting time physical and mechanical properties