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Experimental and Theoretical Study on the Self-Weight Penetration Velocity of Suction Anchor Foundations in Sand

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China Ocean Engineering 2023年第5期37卷 863-875页

作者： SUN Kai MA Hui-huan wang fu-ming School of Civil Engineering Sun Yat-Sen University&Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)Zhuhai 519082China Guangdong Key Laboratory of Oceanic Civil Engineering Guangzhou 510275China

The application of the wellhead suction anchor in the second production test of natural gas hydrates(NGHs)in the South China Sea(SCS)was met with success.This design incorporates a central conductor guide pipe,which distinguishes it from traditional suction foundations.However,this addition resulted in a relatively high penetration resistance and a shallower penetration depth at the self-weight penetration stage.To mitigate this issue,the current study proposes an optimized design where the end of the suction foundation is sharpened.The installation characteristics of the traditional suction foundation and new suction foundation during self-weight penetration into sand are studied through laboratory tests and theoretical analysis.The flat and sharpened bottom shapes are considered in the traditional and new suction models.The effects of the initial penetration velocity on the initial penetration depth and soil plug and impact cavity characteristics are systematically studied.The results show that the self-weight penetration depth of the foundation with a sharpened bottom is 44.5%deeper than that of the foundation with a flat bottom.There are cavities around the foundation at the self-weight penetration stage,and the penetration depth is overestimated by 15%-30%.Finally,a model for predicting the penetration depth of the new suction foundation is proposed.

关键词： suction foundation self-weight penetration penetration velocity soil plug sharpened bottom

Self-Weight Penetration Characteristics of the Suction Foundation with Different Diameters in Sand

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China Ocean Engineering 2022年第5期36卷 743-754页

作者： SUN Kai MA Hui-huan GUO Cheng-chao LI Tao CAO Ding-feng XIE Peng wang fu-ming School of Civil Engineering Sun Yat-sen University&Southern Marine Science and Engineering Guangdong Lab-oratory(Zhuhai)Zhuhai 519082China Guangdong Key Laboratory of Oceanic Civil Engineering Guangzhou 510275China Guangdong Research Center for Underground Space Exploitation Technology Guangzhou 510275China Advanced Energy Science and Technology Guangdong Laboratory(Yangjiang offshore Wind Energy Laboratory) Yangjiang 529500China School of Marine Engineering and Technology Sun Yat-sen UniversityZhuhai 519082China

During the self-weight penetration process of the suction foundation on the dense sand seabed,due to the shallow penetration depth,the excess seepage seawater from the outside to the inside of the foundation may cause the negative pressure penetration process failure.Increasing the self-weight penetration depth has become an important problem for the safe construction of the suction foundation.The new suction anchor foundation has been proposed,and the self-weight penetration characteristics of the traditional suction foundation and the new suction anchor foundation are studied and compared through laboratory experiments and analysis.For the above two foundation types,by considering five foundation diameters and two bottom shapes,20 models are tested with the same penetration energy.The effects of different foundation diameters on the penetration depth,the soil plug characteristics,and the surrounding sand layer are studied.The results show that the penetration depth of the new suction foundation is smaller than that of the traditional suction foundation.With the same penetration energy,the penetration depth of the suction foundation becomes shallower as the diameter increases.The smaller the diameter of the suction foundation,the more likely it is to be fully plugged,and the smaller the height of the soil plug will be.In the stage of self-weight penetration,the impact cavity appears around the foundation,which may affect the stability of the suction foundation.

关键词： suction foundation foundation diameter self-weight penetration soil plugging sand

Constitutive model for Ya'an mudstone based on mesoscopic breakage mechanism

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Journal of Mountain Science 2023年第4期20卷 1159-1169页

作者： HE Yun-yong CHEN Cong wang fu-ming GUO Cheng-chao XIANG Bo YU Di LIU En-long DING Chun School of Civil Engineering Southwest Jiaotong UniversityChengdu610031China Sichuan Highway Planning SurveyDesign and Research Institute LtdChengdu610041China State Key Laboratory of Hydraulics and Mountain River Engineering College of Water Resources and HydropowerSichuan UniversityChengdu610065China School of Civil Engineering Sun Yat-sen UniversityGuangzhou510275China Ya’an Transportation Construction Group Co. Ltd.Ya’an625000China

The slope stability of Ya’an expressway in Sichuan dominated by mudstone strata,is influenced greatly by both the mechanical properties and stressstrain relationship of mudstone.In this paper,the mechanical properties of the Ya’an mudstone samples under triaxial compression conditions were studied,based on an established constitutive model under the framework of breakage mechanics to simulate the mechanical properties of mudstone.Firstly,triaxial compression tests and SEM tests at the confining pressures of 0.5 MPa,1.0 MPa,and 2.0 MPa were carried out on the mudstone samples,and it was found that the mudstone sample undergoes strain softening and dilatancy followed by the volumetric compaction.Then,based on analysis on the breakage mechanism of the above test results,we idealized the mudstone sample as a binary medium material consisting of the bonded elements and frictional elements,of which the bonded elements are composed of solid matrix and pores,and the frictional elements are composed of broken aggregates.During the loading process,the cementation between clay minerals and non-clay minerals in the mudstone sample is first destroyed,leading to the formation of micro-cracks within the particle aggregate,that is,the bonded elements are gradually damaged during the loading process and gradually turned into the frictional elements,and the two jointly bear the external load.The bonded elements are composed of mudstone matrix and pores,which have the cementitious characteristics of mudstone,and the frictional elements are composed of the broken aggregate with the frictional characteristics of the broken particles.Based on the homogenization theory,the constitutive model for the mudstone is established,and the determining method for model parameters is also given.Finally,the results of the triaxial compression tests of the mudstone samples are predicted by the constitutive model proposed here,which can reflect the main mechanical properties of the mudstone samples.

关键词： Mudstone Breakage mechanism Constitutive model Strain softening Binary medium model

Corrosion Products and Formation Mechanism During Initial Stage of Atmospheric Corrosion of Carbon Steel

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Journal of Iron and Steel Research(International) 2008年第5期15卷 42-48页

作者： XIAO Kui DONG Chao-fang LI Xiao-gang wang fu-ming Beijing Key Laboratory for Corrosion Erosion and Surface Technology University of Science and Technology Beijing Beijing 100083 China School of Metallurgical and Ecological Engineering University of Science and Technology Beijing Beijing 100083 China

The formation and development of corrosion products on carbon steel surface during the initial stage of atmospheric corrosion in a laboratory simulated environment have been studied by scanning electron microscopy （SEM） and Raman spectroscopy. The results showed that two different shapes of corrosion products, that is, ring and chain, were formed in the initial stage of corrosion. MnS clusters were found in the nuclei of corrosion products at the active local corrosion sites. The ring-shaped products were composed of lepidocrocite （γ-FeOOH） and maghemite （γ-Fe2O2 ） transformed from lepidocrocite. The chain-type products were goethite （α-FeOOH）. A formation mechanism of the corrosion products is proposed.

关键词： atmospheric corrosion corrosion product carbon steel

Structure and Texture Formation During Single and Double Cold Rolling and Annealing Processes for Nb+Ti Added Interstitial-Free Steels

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Journal of Iron and Steel Research(International) 2013年第5期20卷 42-49页

作者： FENG Yan-qing wang fu-ming TAO Su-fen ZHAO Dian-qing ZHANG Xiao-yan State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing School of Metallurgical and Ecological Engineering University of Science and Technology Beijing Baotou Iron and Steel (Group) Co. Ltd.

The structure and texture formation for single cold rolling （SCR） with annealing and double cold rolling （DCR） with annealing were investigated based on optical microscope and X-ray diffraction （XRD） with a Nb＋Ti bearing interstitial free （IF） steel. The results indicated that DCR recrystallization grain was smaller than that of SCR sample and double cold rolling process resulted in better mechanical properties than those resulted from single cold rolling process with the same total reduction conducted. The plastic strain ratio increases from 2.23 for single cold rolling process to 3.2 for double rolling process. The fish-bone structure was observed in all SCR and DCR samples. DCR annealed sample is made up of equiaxed grains of almost uniform size, whereas SCR annealed sample shows a duplex grain structure, consisting of both large and small-sized grains. （Ti＋Nb）C and Fe（Ti＋Nb）P type precipitates were very rarely observed in SCR annealed and DCR annealed steels. The intensity of {111}∥ND for the DCR annealing was higher than that for SCR annealing.

关键词： single cold rolling double cold rolling Nb Ti IF steel structure texture

Stability analysis of free surface of soil between piles in fabricated recyclable foundation pit supporting structure

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Yantu Lixue/Rock and Soil Mechanics 2020年 41卷 299-305页

作者： Chen, Li-Chao Lin, Pei-Yuan Guo, Cheng-Chao wang, fu-ming School of Civil Engineering Sun Yat-sen University Guangzhou 510275 China Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai) Zhuhai 519080 China Guangdong Provincial Key Laboratory of Oceanic Civil Engineering Sun Yat-sen University Guangzhou 510275 China Guangdong Provincial Research Center for Underground Space Exploitation Technology Guangzhou 510275 China

The stability of the free surface of the soil between the piles is of great significance for the engineering application of the assembled recyclable foundation pit support structure. In this paper, based on the calculation model of wedge-shaped body and the Terzaghi's theory on loosening earth pressure, considering the interaction between the soil and the pile-slab, the calculation formula of the ultimate supporting pressure of the free surface of the soil between the piles is derived from the limit equilibrium condition of the sliding mass. The calculated ultimate supporting pressure is compared with the numerical simulation results of three-dimensional finite element limit analysis to verify the rationality of the calculation method. The simple variable method was used to analyze the effects of soil internal friction angle φ, interface friction angle between soil and plates/piles δ, ground overload P0, spacing between piles B, relative excavation depth H/D, and unloading arch angle β on the ultimate support pressure. The research results can provide a theoretical basis for the soil support between the piles in the pile-slab support structure. © 2020, Science Press. All right reserved.

关键词： Piles

Grain size effect on the assembly quality of micro-scaled barrel formed by microforming

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Advances in Manufacturing 2024年第1期12卷 19-32页

作者： Dien Hu Jieyichen Fang Feng Zeng ming-wang fu Department of Mechanical Engineering Research Institute of Advanced ManufacturingThe Hong Kong Polytechnic UniversityHung HomKowloonHong KongPeople’s Republic of China Xiamen Yulong Machinery Co.Ltd. Xiamen361023FujianPeople’s Republic of China

In this research,a method employing micro-extrusion was designed to produce the micro-scaled barrel-shaped parts with complex geometrical features to study the feasibility of the proposed microforming method and its grain size effect on the formability of the complicated internal features in terms of deformation behavior,material evolution,accuracy of dimensions and final components quality.The results reveal that the deformation behavior is highly affected by grain size and becomes unpredictable with increased grain size.In addition,assembly parameters including feature dimension,tolerance and coaxiality also vary with grain size,and the variation of grain size needs to be accommodated by different assembly types,viz.,clearance fit or transition fit.From the microstructural evolution aspect,it was identified there were two dead zones and four shear bands,and the formation of these deformation zones was barely affected by the variation in grain size.Though bulges,cracks,and fracture induced voids were observed on the surface of the final components,tailoring the microstructure of the working material with finer grains could significantly avoid these defects.This study advances the understanding of forming microparts by extrusion processes and provides guidance for microforming of similar microparts.

关键词： Microformed part Size effect Extrusion Microstructural evolution Dimensions Assembly accuracy

Effect of Al content in molten steel on interaction between MgO-C refractory and SPHC steel

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Journal of Iron and Steel Research(International) 2024年第4期31卷 838-848页

作者： fu-bin Gao fu-ming wang Xiang Zhang Tian-yu Du Xin-hua wangg School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing 100083China Handan Iron and Steel Company Hegang GroupHandan 056015HebeiChina The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan 430081HubeiChina

The effect of Al content in molten steel on the interaction between SPHC steel(0.005-0.068 wt.%Al,and 19×10^(-4)-58×10^(-4)wt.%O)and MgO-C refractory(11.63 wt.%C)was investigated.Non-metallic inclusions in the steel were examined at various periods(0,5,15,30,45,and 60 min)as well as the MgO-C interface after 60 min of corrosion at 1600℃.The results show that when MgO-C refractory comes into contact with SPHC steel,the refractory interface consists of three layers arranged from the innermost to the outermost,including the original refractory layer,the dense MgO layer,and the iron infiltration layer.The carbon in the MgO-C refractories and the Al content in the molten steel undergo a reaction with the MgO in the refractories,resulting in an increase in Mg concentration in the steel.Increasing Al content in the molten steel from 0.005 to 0.068 wt.%causes a spinel layer to appear at the interface,and the disappearance time of Al_(2)O_(3) inclusions in the steel decreases from 60 to 30 min,while the average MgO content in inclusions increases.Therefore,controlling the Al content in the molten steel and the smelting duration can help regulate the formation of spinel inclusionsinthe steel.

关键词： MgO-C refractory SPHC steel Inclusion-Spinel Al-killed steel Interfacial reaction

A multifunctional electrolyte additive for zinc-ion capacitors with low temperature resistant and long lifespan

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Journal of Energy Chemistry 2024年第7期94卷 477-485页

作者： ming Sun Zekai Zhang Shuqing fu Yifan Zhang Ruoyu wang Hongchun Mu Cheng Lian Wenqiang wang Gengchao wang Shanghai Engineering Research Center of Hierarchical Nanomaterials Shanghai Key Laboratory of Advanced Polymeric MaterialsSchool of Materials Science and EngineeringEast China University of Science and TechnologyShanghai 200237China State Key Laboratory of Chemical Engineering Shanghai Engineering Research Center of Hierarchical NanomaterialsFrontiers Science Center for Materiobiology and Dynamic Chemistryand School of Chemistry and Molecular EngineeringEast China University of Science and TechnologyShanghai 200237China State Key Laboratory of Molecular Engineering of Polymers Department of Macromolecular ScienceFudan UniversityShanghai 200438China

Aqueous zinc-ion capacitors(ziCs)are considered as potential candidates for next generation electro-chemical energy storage devices due to their high safety and low cost.However,the existing aqueous ZiCs usually have the problems of zinc dendrite growth and unsatisfactory performance at low temper-ature.Herein,an erythritol(Eryt)additive with inhibition of zinc dendrites and anti-freezing capability was introduced into the ZnSO_(4) electrolyte.The experimental characterization and theoretical calculation confirm that the Eryt adsorbed on the surface of zinc anodes regulates the deposition orientation of Zn^(2+)and inhibits the formation of dendrites.It also reconstructs the solvation structure in the electrolyte to reduce water activity,enabling the electrolyte to have a lower freezing point for operation at low tem-perature.With the assistance of Eryt,the ZnZn symmetric cell exhibits a long cycle life of 2000 h,while the ZIC assembled with activated carbon(AC)cathode and zinc anode(ZnllAC)maintains a capacity retention of 98.2%after 30,000 cycles at a current density of 10 A g^(-1)(even after 10,000 cycles at-20°C,the capacity retention rate reached 94.8%.).This work provides a highly scalable,low-cost and effective strategy for the protection of the anodes of low-temperature aqueous ZiCs.

关键词： Zinc-ioncapacitors Electrolyte additive Dendrite-free Freeze-resistant electrolyte