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Coupling effect of cement-stabilization and biopolymer-modification on the mechanical behavior of dredged sediment

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第8期16卷 3284-3298页

作者： lei lang Jiangshan Li Xiao Huang Ping Wang Wei Zhang State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China Hubei Provincial Key Laboratory of Contaminated Sludge and Soil Science and Engineering Wuhan430071China University of Chinese Academy of Sciences Beijing100049China

Nowadays,biopolymer stabilization as a promising eco-friendly approach in soft ground improvement has attracted wide ***,the feasibility of using biopolymer as a green additive of cementstabilized dredged sediment(CDS)with high water content is still *** this study,guar gum(GG)and xanthan gum(XG)were adopted as typical biopolymers,and a series of unconfined compressive strength(UCS),splitting tensile strength(STS)and scanning electron microscopy(SEM)tests were performed to evaluate the mechanical and microstructural properties of XG-and GG-modified CDSs considering several factors including biopolymer modification,binderesoil ratio and wateresolid ***,the micro-mechanisms revealing the evolutions of mechanical properties of biopolymermodified CDS were *** results indicate that the addition of XG can effectively improve the strength of CDS,while the GG has a side *** XG content of 9%was recommended,which can improve the 7 d-and 28 d-UCSs by 196%and 51.8%,together with the 7 d-and 28 d-STSs by 118.3%and 42.2%,*** the binderesoil ratio or decreasing the wateresolid ratio significantly improved the strength gaining but aggravated the brittleness characteristics of *** XG to CDS contributed to the formation of microstructure with more compactness and higher cementation degrees of ordinary Portland cement(OPC)-XG-stabilized DS(CXDS).The micro-mechanism models revealing the interactions of multiple media including OPC cementation,biopolymer film bonding and bridging effects inside CXDS were *** key findings confirm the feasibility of XG modification as a green and high-efficiency mean for improving the mechanical properties of CDS.

关键词： Dredged sediment(DS) Stabilization Biopolymer modification Mechanical properties Micro-mechanism

乡村振兴视域下农村集体经济组织有限破产制度探讨

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法学（汉斯） 2024年第5期12卷 3440-3444页

作者：雷浪江南大学法学院江苏无锡

农村集体经济组织特别法人地位的确立,对其参与市场活动,发展新型农村集体经济具有重大意义,但是对于能否适用破产制度成为农村集体经济组织立法的重要问题,目前学界主要有肯定说与否定说两种截然不同的观点。对此,本文拟从农村集体经... 详细信息

农村集体经济组织特别法人地位的确立,对其参与市场活动,发展新型农村集体经济具有重大意义,但是对于能否适用破产制度成为农村集体经济组织立法的重要问题,目前学界主要有肯定说与否定说两种截然不同的观点。对此,本文拟从农村集体经济组织是否适用破产制度的观点出发,以“政经分离”是农村改革发展的方向以及农村集体经济组织财产处置的特殊性为基础,从而承认农村集体经济组织具有破产能力,同时应对其责任财产的范围予以限定,使之适用有限破产制度时能够更加协调。

关键词：乡村振兴农村集体经济组织破产能力责任财产

High-efficiency stabilization of dredged sediment using nano-modified and chemical-activated binary cement

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第8期15卷 2117-2131页

作者： lei lang Bing Chen Jiangshan Li State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China Department of Civil Engineering Shanghai Jiao Tong UniversityShanghai200240China

High-efficiency disposal of dredged sediment(DS)has become an imperative geo-environmental engineering issue due to the limited landfilling space and severe environmental *** study firstly developed a novel high-efficiency nano-modified and chemical-activated binary cement(NBC),which was composed of binary cement(BC)consisting ordinary Portland cement(OPC)and ground granulated blast-furnace slag(GGBS),chemical-activator and *** effects of chemical-activation and nano-modification on the strength development of BC-stabilized DS(BCDS),and the optimum mix of NBC were respectively achieved via a series of unconfined compressive strength and orthogonal ***,the high-efficiency and economic applicability of NBC in DS stabilization were evaluated by comparing with ***,the microstructure and mineral composition evolutions inside NBCstabilized DS(NDS)were explored by conducting X-ray diffraction(XRD)and scanning electron microscopy(SEM)*** results show that both chemical-activation and nano-modification could effectively improve the strength gain of BCDS,and compared with single chemical-activator and nanomodifier,the composite chemical-activators and nano-modifiers exhibited better *** on BC with OPC/GGBS mass ratio of 1:1,both anhydrous sodium metasilicate/anhydrous sodium sulfate(SM/SS)and nano-SiO_(2)/nano-MgO(NS/NM)with mass ratio of 1:9 were respectively determined to be optimum chemical-activator and *** optimum mass ratio of BC,SM/SS and NS/NM was 20:2:1,*** optimum mix of *** with OPC,NBC exhibited higher stabilization efficiency and better economic *** generation of calcium silicate hydrate(CSH),calcium aluminate hydrate(CAH)and ettringite contributed to the formation of dense cemented soil matrix inside NDS,and a conceptual micro-mechanism model characterizing the strength development under the coupling action of chemical-activation and nano-modification was prop

关键词： Dredged sediment(DS) Stabilization Chemical-activation Nano-modification Microstructure

Modification of nanoparticles for the strength enhancing of cementstabilized dredged sludge

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Journal of Rock Mechanics and Geotechnical Engineering 2021年第3期13卷 694-704页

作者： lei lang Bing Chen Haijuan Duan State Key Laboratory of Ocean Engineering Shanghai Jiao Tong UniversityShanghaiChina Shanghai Key Laboratory for Digital Maintenance of Buildings and Infrastructure Department of Civil EngineeringShanghai Jiao Tong UniversityShanghaiChina

This paper investigates the effectiveness of nano-modification on the strength enhancement of cementstabilized dredged sludge(CDS).Three types of nanoparticles including nano-SiO2(NS),nano-Al2O3(NA)and nano-MgO(NM)were used as cement admixtures for dredged sludge *** of single nanoparticle content,mass ratio of composite nanoparticles and curing time on the strength development of CDS were evaluated via a series of unconfined compressive strength(UCS)*** pH evolutions of CDS caused by nanoparticles were also examined by a range of pH ***,micromechanisms reflecting the strength evolutions were analyzed by performing scanning electron microscopy(SEM)and X-ray diffraction(XRD)*** results indicated that adding nanoparticles can significantly improve the UCS of *** single nano-modification,the optimum contents of NS,NA and NM were 4%e6%,6%and 8%,which can increase the 7-and 28-d UCSs of CDS by 38%and 50%,17%and 35%,65%and 67%,*** with single nano-modification,composite nano-modifications were more effective in improving the strength gain of *** optimum mass ratios of composite nanoparticles,namely NS/NA,NS/NM and NA/NM,were 9/1,3/7 and 3/7,*** on the strength growth rate,the composite nanoparticles with NS/NM of 3/7 were highly *** addition of nanoparticles obviously affected the pH evolution of CDS,which was mainly determined by the difference of OHproduction and consumption inside nano-modified *** microstructural analysis revealed that C-S-H and C-A-H gels are the main cementitious products,and the addition of nanoparticles can obviously contribute to a denser and more homogenous microstructure of CDS.

关键词： Cement-stabilized dredged sludge(CDS) Nano-modification Strength development pH level Microstructure

中国国债收益率曲线的混频周期机制研究——基于区制转移混频期限结构模型

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兰州财经大学学报 2024年第3期40卷 1-17页

作者：尚玉皇季朗磊西南财经大学中国金融研究院四川成都611130 浙江浙商金控有限公司浙江杭州200433

文章在混频数据信息的现实条件下,为充分揭示我国国债收益率曲线的混频周期(非线性)特征及其与宏观经济的作用机制,提出了一种新的区制转移混频Nelson-Siegel期限结构(MS-MF-NS)模型。研究结果表明:与传统混频模型相比,MS-MF-NS模型因... 详细信息

文章在混频数据信息的现实条件下,为充分揭示我国国债收益率曲线的混频周期(非线性)特征及其与宏观经济的作用机制,提出了一种新的区制转移混频Nelson-Siegel期限结构(MS-MF-NS)模型。研究结果表明:与传统混频模型相比,MS-MF-NS模型因恰当引入经济周期行为而进一步提高了国债收益率的拟合效果;利率期限结构具有显著的周期行为特征,该特征受到期限结构斜率因子的逆经济周期行为的影响;在考虑经济周期因素后,斜率因子对宏观经济预测提供更多的前瞻性信息,基于通胀预期机制斜率因子对通货膨胀的预测作用也会显著增强;在非线性模型框架下,因合理刻画宏观经济对国债收益率作用机制的周期性差异,使得宏观基本面对收益率曲线及期限结构因子的贡献更加显著。货币政策调控需要考虑期限结构的非线性作用机制,基于统筹发展与安全的思想理念适度微调,同时需要关注货币政策跨周期和逆周期调节对期限结构的反馈效应。

关键词：期限结构区制转移混频数据经济周期

内镜辅助下无切口不翻瓣再生技术治疗牙槽骨角型吸收的效果评价

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上海口腔医学 2024年第1期33卷 80-84页

作者：史佳虹李静雯蒋立姗雷浪李厚轩南京大学医学院附属口腔医院南京市口腔医院南京大学口腔医学研究所牙周病科江苏南京210008 南京大学医学院附属口腔医院南京市口腔医院南京大学口腔医学研究所正畸科江苏南京210008

目的:探讨内镜辅助下无切口不翻瓣再生技术(non-incisional technique,NIT)治疗牙槽骨角型吸收的效果。方法:选择13例重度牙周炎患者的13颗患牙,均存在邻面牙槽骨角型吸收,在经过牙周基础治疗后6周接受NIT治疗。NIT治疗过程为在内镜下... 详细信息

目的:探讨内镜辅助下无切口不翻瓣再生技术(non-incisional technique,NIT)治疗牙槽骨角型吸收的效果。方法:选择13例重度牙周炎患者的13颗患牙,均存在邻面牙槽骨角型吸收,在经过牙周基础治疗后6周接受NIT治疗。NIT治疗过程为在内镜下完成清创后填入骨再生材料,记录NIT治疗前及术后2年术区探诊深度(probing depth,PD)、临床附着水平(clinical attachment level,CAL)、牙龈退缩(gingival recession,GR)及影像学指标变化。采用SPSS22.0软件包对数据进行统计学分析。结果:NIT术后2年随访结果与术前相比,CAL降低(3.65±2.10) mm(P<0.001),PD降低(4.42±1.66) mm(P<0.001),GR为(0.38±0.87)mm (P=0.25),影像学骨下袋深度降低显著(P<0.001)。结论 :对于牙槽骨角型吸收位点,NIT治疗可以在不翻瓣情况下获得良好的牙周再生效果。

关键词：牙周炎内镜牙周再生微创治疗

Autogenous healing mechanism of cement-based materials

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结构与土木工程前沿:英文版 2023年第6期17卷 948-963页

作者： Desheng LI Hao ZHENG Kang GU lei lang Shang SHI Bing CHEN Department of Civil Engineering School of ScienceNanjing University of Science and TechnologyNanjing210094China School of Transportation Science and Engineering Harbin Institute of TechnologyHarbin150090China State Key Laboratory of Ocean Engineering Shanghai Jiao Tong UniversityShanghai200240China State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsWuhan430071China

Autogenous self-healing is the innate and fundamental repair capability of cement-based materials for healing *** researchers have investigated factors that influence autogenous ***,systematic research on the autogenous healing mechanism of cement-based materials is *** healing process mainly involves a chemical process,including further hydration of unhydrated cement and carbonation of calcium oxide and calcium ***,the autogenous healing process is influenced by the material constituents of the cement composite and the ambient *** this study,different factors influencing the healing process of cement-based materials were *** electron microscopy and optical microscopy were used to examine the autogenous healing mechanism,and the maximum healing capacity was ***,detailed theoretical analysis and quantitative detection of autogenous healing were *** study provides a valuable reference for developing an improved healing technique for cement-based composites.

关键词： autogenous healing cement-based materials healing mechanism aggregation effect

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多跨矮塔斜拉桥超高墩合理形式比选

交通科技与经济 2024年第1期26卷 57-63页

作者：苗建宝刘亚文张小亮雷浪西安公路研究院有限公司西安710065 湖南大学长沙410082

为研究多跨矮塔斜拉桥超高墩合理形式,以多跨矮塔斜拉桥超高墩为对象,综合对比分析超高墩结构布置形式和受力特点,按截面特性相似的原则提出双薄壁墩、单薄壁墩、组合式墩、叠合式墩四种适用于依托工程的超高墩形式。采用全桥有限元和... 详细信息

为研究多跨矮塔斜拉桥超高墩合理形式,以多跨矮塔斜拉桥超高墩为对象,综合对比分析超高墩结构布置形式和受力特点,按截面特性相似的原则提出双薄壁墩、单薄壁墩、组合式墩、叠合式墩四种适用于依托工程的超高墩形式。采用全桥有限元和理论方法,分析不同工况下主梁和桥墩关键截面的内力和墩顶位移、施工和成桥运营阶段的稳定性、E1地震作用下的动力及抗震性能。结果表明:四种方案均满足施工阶段和成桥运营阶段下的稳定性要求,双薄壁墩前三阶均为纵向失稳且稳定安全系数变化较小;在E1地震荷载作用下,双薄壁墩内力响应最小,但位移响应较大,单薄壁墩和叠合式墩与之相反,组合式墩则较均衡。考虑结构整体受力性能,建议多跨矮塔斜拉桥超高墩桥梁选用双薄壁墩或组合式墩。

关键词：桥梁工程超高墩有限元分析稳定性抗震性能

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基于模型试验的体外预应力加固梁应力增量分析

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水利与建筑工程学报 2024年第2期22卷 94-101页

作者：杨永恒原淼淼刘喆雷浪陕西交通控股集团有限公司陕西西安710065 内蒙古科技大学内蒙古包头014010 西安公路研究院有限公司陕西西安710065

为研究不同体外预应力加固方式对预应力混凝土(PC)梁受力性能的影响,对三根T形简支梁进行静载试验,观察PC梁的裂缝开展以及破坏情况,分析荷载、挠度、应变等的变化趋势,并提出预应力筋的极限应力计算公式,探讨体外加固预应力筋的有效高... 详细信息

为研究不同体外预应力加固方式对预应力混凝土(PC)梁受力性能的影响,对三根T形简支梁进行静载试验,观察PC梁的裂缝开展以及破坏情况,分析荷载、挠度、应变等的变化趋势,并提出预应力筋的极限应力计算公式,探讨体外加固预应力筋的有效高度、面积以及有效应力对体内外预应力筋应力增量的影响。结果表明:与未加固梁A1梁相比,A2梁的承载力提高了57.5%,A3梁的承载力提高了52.7%,可见不同的体外预应力加固方式对PC梁的承载力均有不同程度的提高;体外加固T梁的荷载-挠度曲线基本呈三折线,且预应力筋应力增量与跨中挠度基本呈线性关系;通过对比发现,体外筋有效高度增加时,体内外筋的应力增量分别随之减小、增加,而在其他因素影响下,体内外筋的应力增量均逐渐减小。

关键词：体外预应力加固预应力混凝土梁极限应力应力增量