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沙尘暴 2

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风化砂 2

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三维过程；三元数；最小均方；卡尔曼滤波器 1

不毛之地 1

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人口、资源与环境 1

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低光增强；过滤—群聚注意力；密集连接金字塔；递归网络 1

保持边缘的自适应滤波器 1

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分布式卡尔曼一致性滤波；事件触发机制；信息年龄（AoI）；稳定性分析；能量优化 1

分布式融合滤波；多传感器非线性奇异系统；动态事件触发策略；抗野值滤波器；一致有界 1

分析滤波器；线性预测；窄带语音水印；通带激励替代；能量规范化；谱包络成形；合成滤波器 1

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Impacts of backwashing on micropollutant removal and associated microbial assembly processes in sand

《环境科学与工程前沿（英文）》 2023年 第17卷 第3期 doi: 10.1007/s11783-023-1634-z

摘要：

● Backwashing in sand filters with 2-h and 4-h EBCTs was simulated.

关键词： Sand filter     Backwashing     Recovery     Micropollutants     Community composition    

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Numerical simulation of compaction parameters for sand-filled embankment using large thickness sand filling

Wentao WANG, Chongzhi TU, Rong LUO

《结构与土木工程前沿（英文）》 2018年 第12卷 第4期   页码 568-576 doi: 10.1007/s11709-017-0444-4

摘要： The study uses the finite element method to simulate a new technique of highway sand embankment filling in Jianghan Plain district, which can raise the thickness of sand-filled layer from 30 cm to 70 cm and can significantly shorten the construction period based on the guarantee of sand embankment construction quality. After simulating the three compacting proposals carried out on the field test, the study uses COMSOL software to research on the compacting effects of sand-filled layers in larger thicknesses by 22 ton vibratory roller alone, and then to investigate the steady compacting effect of 12 ton vibratory roller. The simulation results indicate that the sand-filled layer thickness of 70 cm is suitable for the new sand filling technique, and the sand-filled embankment project with tight construction period is suggested to choose the 12 ton vibration roller for steady compaction.

关键词： sand embankment     compaction in large thickness     numerical simulation     small size vibratory roller     steady compaction    

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Unified description of sand behavior

Feng ZHANG, Bin YE, Guanlin YE

《结构与土木工程前沿（英文）》 2011年 第5卷 第2期   页码 121-150 doi: 10.1007/s11709-011-0104-z

摘要： In this paper, the mechanical behavior of sand, was systematically described and modeled with a elastoplastic model proposed by Zhang et al. [ ]. Without losing the generality of the sand, a specific sand called as Toyoura sand, a typical clean sand found in Japan, has been discussed in detail. In the model, the results of conventional triaxial tests of the sand under different loading and drainage conditions were simulated with a fixed set of material parameters. The model only employs eight parameters among which five parameters are the same as those used in Cam-clay model. Once the parameters are determined with the conventional drained triaxial compression tests and undrained triaxial cyclic loading tests, then they are fixed to uniquely describe the overall mechanical behaviors of the Toyoura sand, without changing the values of the eight parameters irrespective of what kind of the loadings or the drainage conditions may be. The capability of the model is discussed in a theoretical way.

关键词： constitutive model     sand     stress-induced anisotropy     density     structure    

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Research review of the cement sand and gravel (CSG) dam

Xin CAI, Yingli WU, Xingwen GUO, Yu MING

《结构与土木工程前沿（英文）》 2012年 第6卷 第1期   页码 19-24 doi: 10.1007/s11709-012-0145-y

摘要： The cement sand and gravel (CSG) dam is a new style of dam that owes the advantages both of the concrete faced rock-fill dam (CRFD) and roller compacted concrete (RCC) gravity dam, because of which it has attracted much attention of experts home and abroad. At present, some researches on physic-mechanical property of CSG material and work behavior of CSG dam have been done. This paper introduces the development and characteristics of CSG dam systematically, and summarizes the progress of the study on basic tests, constitutive relation of CSG material and numerical analysis of CSG dam, in addition, indicates research and application aspect of the dam.

关键词： cement sand and gravel (CSG) dam     cement sand and gravel (CSG) material     research review    

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Effects of microfine aggregate in manufactured sand on bleeding and plastic shrinkage cracking of concrete

Branavan ARULMOLY; Chaminda KONTHESINGHA; Anura NANAYAKKARA

《结构与土木工程前沿（英文）》 2022年 第16卷 第11期   页码 1453-1473 doi: 10.1007/s11709-022-0877-2

摘要： Construction industries have started to utilize manufactured sand (MS) as an effective alternative for river sand in concrete. High-grade parent rocks are crushed to obtain MS, which also produces a considerable amount of microfine aggregate (MFA). The higher percentage of MFA could lead to both positive and negative effects on the performance of cement-based mixes. This research was done to examine the influence of varying MFA levels, specifically 0%, 3%, 6%, 9%, and 12% (by weight) as the partial replacements of MS on bleeding and plastic shrinkage cracking of concrete. In addition to the varying MFA levels, some concrete mixes also included fly ash (FA) and superplasticizer to investigate the effect of free-water content in the mixes. The bleeding test data were taken as on-site measurements, while the cracks from the plastic shrinkage cracking test were evaluated using an image processing technique. The results concluded that the MFA replacements and the effective water-to-cement ratio have a significant effect on the selected concrete properties. With the increasing replacement levels, cumulative bleeding and crack initiation life gradually decreased, while a progressive increase was observed for crack width, crack length, and crack area.

关键词： manufactured sand     fresh concrete     microfines     admixtures     shrinkage     cracking    

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Destructive and non-destructive evaluation of concrete for optimum sand to aggregate volume ratio

《结构与土木工程前沿（英文）》 2021年 第15卷 第6期   页码 1400-1414 doi: 10.1007/s11709-021-0779-8

摘要： Aggregates are the biggest contributor to concrete volume and are a crucial parameter in dictating its mechanical properties. As such, a detailed experimental investigation was carried out to evaluate the effect of sand-to-aggregate volume ratio (s/a) on the mechanical properties of concrete utilizing both destructive and non-destructive testing (employing UPV (ultrasonic pulse velocity) measurements). For investigation, standard cylindrical concrete samples were made with different s/a (0.36, 0.40, 0.44, 0.48, 0.52, and 0.56), cement content (340 and 450 kg/m3), water-to-cement ratio (0.45 and 0.50), and maximum aggregate size (12 and 19 mm). The effect of these design parameters on the 7, 14, and 28 d compressive strength, tensile strength, elastic modulus, and UPV of concrete were assessed. The careful analysis demonstrates that aggregate proportions and size need to be optimized for formulating mix designs; optimum ratios of s/a were found to be 0.40 and 0.44 for the maximum aggregate size of 12 and 19 mm, respectively, irrespective of the W/C (water-to-cement) and cement content.

关键词： aggregates     non-destructive testing     sand-to-aggregate volume ratio (s/a)     maximum aggregate size (MAS)    

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Effects of coarse and fine aggregates on long-term mechanical properties of sea sand recycled aggregate

《结构与土木工程前沿（英文）》 2021年 第15卷 第3期   页码 754-772 doi: 10.1007/s11709-021-0711-2

摘要： Typical effects of coarse and fine aggregates on the long-term properties of sea sand recycled aggregate concrete (SSRAC) are analyzed by a series of axial compression tests. Two different types of fine (coarse) aggregates are considered: sea sand and river sand (natural and recycled coarse aggregates). Variations in SSRAC properties at different ages are investigated. A novel test system is developed via axial compression experiments and the digital image correlation method to obtain the deformation field and crack development of concrete. Supportive results show that the compressive strength of SSRAC increase with decreasing recycled coarse aggregate replacement percentage and increasing sea sand chloride ion content. The elastic modulus of SSRAC increases with age. However, the Poisson’s ratio reduces after 2 years. Typical axial stress–strain curves of SSRAC vary with age. Generally, the effect of coarse aggregates on the axial deformation of SSRAC is clear; however, the deformation differences between coarse aggregate and cement mortar reduce by adopting sea sand. The aggregate type changes the crack characteristics and propagation of SSRAC. Finally, an analytical expression is suggested to construct the long-term stress–strain curve of SSRAC.

关键词： sea sand recycled aggregate concrete     recycled coarse aggregate replacement percentage     sea sand chloride ion content     long-term mechanical properties     stress–strain curve    

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Performance of fiber reinforced clayey sand composite

Amin CHEGENIZADEH, Hamid NIKRAZ

《结构与土木工程前沿（英文）》 2012年 第6卷 第2期   页码 147-152 doi: 10.1007/s11709-012-0158-6

摘要： Soils and their related behavior have always been the subject of many studies. Recent researches show some interests in investigation of inclusion of randomly distributed fiber in soil. This study focuses on effect of fiber inclusion on the strength and other parameters of clayey sand composite material. First part of this study is related to effective parameters on strength of the clayey sand composite with using natural fiber and plastic fiber and different fiber contents and length. Triaxial consolidated undrained (CU) tests were carried out to investigate behavior of the composite under different condition. The fiber percentage varied from 0% (for unreinforced samples) to 4% and fiber length varied from 8 to 25 mm. The fiber length and fiber content found to play important rule on the strength of fiber reinforced composite.

关键词： triaxial     consolidated undrained (CU)     fiber     strength    

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The coupling of sand with ZVI/oxidants achieved proportional and highly efficient removal of arsenic

Sana Ullah, Xuejun Guo, Xiaoyan Luo, Xiangyuan Zhang, Yameng Li, Ziyu Liang

《环境科学与工程前沿（英文）》 2020年 第14卷 第6期 doi: 10.1007/s11783-020-1273-6

摘要： Abstract • Simply doping sands with ZVI achieved an even activation of ZVI by oxidants. • Sand doping facilitated proportional As trapping along the ZVI/oxidants column. • ZVI/sand/oxidants are highly efficient for arsenic removal. • ZVI/sand/oxidants reduced significantly the Fe2+ leaching and effluent turbidity. • More than 54% of arsenic was reduced to As(III) in ZVI/sand/oxidants system. The coupling of zero-valent iron (ZVI) with common oxidants has recently achieved very rapid and highly efficient removal of Heavy metals from wastewater. However, the uniform activation of ZVI throughout the column and the proportional removal of target contaminants are urgently required for the prevention of premature filter clogging and the extension of the effective column operational time. In this study, we successfully achieved this objective by simply doping granular sand with ZVI at appropriate weight ratios. When pure ZVI packed column was spiked with oxidants, the majority of As trapping occurred between the column inlet and the first sampling point. In a packed column with a 1:20 mixture of ZVI and sand, the average As removal efficiency was 36 (1st), 13.1 (2nd), 18.5 (3rd), 19.2 (4th) and 5.9% (5th outlet). The overall arsenic removal performance of the composite filling system of ZVI/sand was equally as efficient as that of the previous pure ZVI-packed system. Moreover, the leaching of Fe was significantly reduced with an increased sand ratio, resulting in clearer water with less turbidity. The results of X-ray photoelectron spectroscopy (XPS) demonstrated that more than 54% of the arsenic was reduced to As(III). X-ray diffraction (XRD) and scanning electron microscopy (SEM) confirmed the extensive corrosion of the ZVI surface, which resulted in various species of iron oxyhydroxides responsible for the highly efficient sequester of arsenic through reduction, adsorption, and coprecipitation.

关键词： Arsenic     ZVI     Sand     Oxidants     Fixed-bed Column     Removal    

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Effect of microlimestone on properties of self-consolidating concrete with manufactured sand and mineral

Fulin Qu, Wengui Li, Xiaohui Zeng, Zhiyu Luo, Kejin Wang, Daichao Sheng

《结构与土木工程前沿（英文）》 2020年 第14卷 第6期   页码 1545-1560 doi: 10.1007/s11709-020-0678-4

摘要： Self-consolidating concrete (SCC) with manufactured sand (MSCC) is crucial to guarantee the quality of concrete construction technology and the associated property. The properties of MSCC with different microlimestone powder (MLS) replacements of retreated manufactured sand (TMsand) are investigated in this study. The result indicates that high-performance SCC, made using TMsand (TMSCC), achieved high workability, good mechanical properties, and durability by optimizing MLS content and adding fly ash and silica fume. In particular, the TMSCC with 12% MLS content exhibits the best workability, and the TMSCC with 4% MLS content has the highest strength in the late age, which is even better than that of SCC made with the river sand (Rsand). Though MLS content slightly affects the hydration reaction of cement and mainly plays a role in the nucleation process in concrete structures compared to silica fume and fly ash, increasing MLS content can evidently have a significant impact on the early age hydration progress. TMsand with MLS content ranging from 8% to 12% may be a suitable alternative for the Rsand used in the SCC as fine aggregate. The obtained results can be used to promote the application of SCC made with manufactured sand and mineral admixtures for concrete-based infrastructure.

关键词： microlimestone powder     manufactured sand     retreated manufactured sand     self-consolidating concrete     mineral admixture    

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Utilization of MSWI fly ash as partial cement or sand substitute with focus on cementing efficiency and

Lei Zheng, Xingbao Gao, Wei Wang, Zifu Li, Lingling Zhang, Shikun Cheng

《环境科学与工程前沿（英文）》 2020年 第14卷 第1期 doi: 10.1007/s11783-019-1184-6

摘要： Washed MSWI fly ash was used as partial cement or sand substitute. Sand replacing is beneficial for strength, while cement replacement reduces strength. Cementing efficiency factor and mortar pore structure explain the strength results. Health risk assessment was conducted for MSWI fly ash blended cement mortar. CR and HI contributed by different exposures and heavy metals were analyzed. The strength of cement substituted mortar decreases with the increase in fly ash amount, whereas the strength increases when the fly ash is blended as sand substitute. A mortar with highest strength (compressive strength= 30.2 Mpa; flexural strength= 7.0 Mpa) was obtained when the sand replacement ratio was 0.75%. The k value (cementing efficiency) of fly ash varied between 0.36 and 0.15 for the fly ash fraction in binder between 5% and 25%. The k values of fly ash used for sand replacement were all significantly above that used for cement substitution. The macropores assigned to the gaps between particles decreased when the fly ash was used as sand replacement, providing an explanation for the strength enhancement. The waste-extraction procedure (toxicity-sulphuric acid and nitric acid method (HJ/T 299-2007)) was used to evaluate metal leaching, indicating the reuse possibility of fly ash blended mortar. For the mortar with the mass ratio of fly ash to binder of 0.5%, the carcinogenic risks (CR) and non-carcinogenic hazard quotient (HQ) in sensitive scenario for blended mortar utilization were 9.66 × 10-7 and 0.06, respectively; these results were both lower than the threshold values, showing an acceptable health risk. The CR (9.89 × 10-5) and HQ (3.89) of the non-sensitive scenario for fly ash treatment exceeded the acceptable threshold values, indicating health risks to onsite workers. The main contributor to the carcinogenic and non-carcinogenic risk is Cr and Cd, respectively. The CR and HQ from inhalation was the main route of heavy metal exposure.

关键词： MSWI fly ash     Cementing efficiency     Health risk assessment of heavy metal     Sand replacement     Cement replacement    

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掺砂率及初始干密度对改良膨胀土无荷膨胀率影响研究

杨俊,杨志,张国栋,唐云伟,陈红萍

《中国工程科学》 2014年 第16卷 第2期   页码 73-78

摘要：

本文通过室内无荷膨胀率试验，对宜昌市某一级公路改建工程项目路段的膨胀土进行了研究。重点分析了无荷膨胀率与时间、掺砂比例、初始干密度之间的关系，试验研究表明：无荷膨胀变形主要分为快速膨胀、减速膨胀和最终稳定3 个阶段；在初始干密度一定时，风化砂改性土的无荷膨胀率会随着掺砂比例的增大先迅速降低然后缓慢降低，风化砂改性土的无荷膨胀率对较大的掺砂量不敏感；在相同的掺砂比例下，风化砂改性土的无荷膨胀率随着初始干密度的增大会迅速增大，它们之间有很好的线性相关性，膨胀土在进行路基填筑时，控制初始干密度有助于减小其膨胀变形，保证路基填土的稳定性。

关键词： 膨胀土     风化砂     初始干密度     掺砂比例     无荷膨胀率    

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Evaluation of soil microbial toxicity of waste foundry sand for soil-related reuse

Haifeng ZHANG, Lu SU, Xiangyu LI, Jiane ZUO, Guangli LIU, Yujue WANG

《环境科学与工程前沿（英文）》 2014年 第8卷 第1期   页码 89-98 doi: 10.1007/s11783-013-0591-3

摘要： The relationship between the chemical contaminants and soil microbial toxicity of waste foundry sand (WFS) was investigated. Five different types of WFS from typical ferrous, aluminum, and steel foundries in China were examined for total metals, leachable metals, and organic contaminants. The soil microbial toxicity of each WFS was evaluated by measuring the dehydrogenase activity (DHA) of a blended soil and WFS mixture and then comparing it to that of unblended soil. The results show that the five WFSs had very different compositions of metal and organic contaminants and thus exhibited very different levels of soil microbial inhibition when blended with soil. For a given WFS blended with soil in the range of 10 wt.%–50 wt.% WFS, the DHA decreased almost linearly with increased blending ratio. Furthermore, for a given blending ratio, the WFSs with higher concentrations of metal and organic contaminants exhibited greater microbial toxicity. Correlation analysis shows that the relationship between ecotoxicity and metal and organic contaminants of WFSs can be described by an empirical logarithmic linear model. This model may be used to control WFS blending ratios in soil-related applications based on chemical analysis results to prevent significant inhibition of soil microbial activity.

关键词： waste foundry sand     toxicity     bioassay     soil microbial activity     waste reuse    

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Compressive behavior and microstructure of concrete mixed with natural seawater and sea sand

《结构与土木工程前沿（英文）》 2021年 第15卷 第6期   页码 1347-1357 doi: 10.1007/s11709-021-0780-2

摘要： Noncorrosive reinforcement materials facilitate producing structural concrete with seawater and sea sand. This study investigated the properties of seawater and sea sand concrete (SSC), considering the curing age (3, 7, 14, 21, 28, 60, and 150 d) and strength grade (C30, C40, and C60). The compressive behavior of SSC was obtained by compressive tests and digital image correction (DIC) technique. Scanning electron microscope (SEM) and X-ray powder diffraction (XRD) methods were applied to understand the microstructure and hydration products of cement in SSC. Results revealed a 30% decrease in compressive strength for C30 and C40 SSC from 60 to 150 d, and a less than 5% decrease for C60 from 28 to 150 d. DIC results revealed significant cracking and crushing from 80% to 100% of compressive strength. SEM images showed a more compact microstructure in higher strength SSC. XRD patterns identified Friedel’s salt phase due to the chlorides brought by seawater and sea sand. The findings in this study can provide more insights into the microstructure of SSC along with its short- and long-term compressive behavior.

关键词： seawater and sea sand concrete     compressive strength     strain field     microstructure     hydration products    

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Implicit Heaviside filter with high continuity based on suitably graded THB splines

《机械工程前沿（英文）》 2022年 第17卷 第1期   页码 14-14 doi: 10.1007/s11465-021-0670-2

摘要： The variable density topology optimization (TO) method has been applied to various engineering fields because it can effectively and efficiently generate the conceptual design for engineering structures. However, it suffers from the problem of low continuity resulting from the discreteness of both design variables and explicit Heaviside filter. In this paper, an implicit Heaviside filter with high continuity is introduced to generate black and white designs for TO where the design space is parameterized by suitably graded truncated hierarchical B-splines (THB). In this approach, the fixed analysis mesh of isogeometric analysis is decoupled from the design mesh, whose adaptivity is implemented by truncated hierarchical B-spline subjected to an admissible requirement. Through the intrinsic local support and high continuity of THB basis, an implicit adaptively adjusted Heaviside filter is obtained to remove the checkboard patterns and generate black and white designs. Threefold advantages are attained in the proposed filter: a) The connection between analysis mesh and adaptive design mesh is easily established compared with the traditional adaptive TO method using nodal density; b) the efficiency in updating design variables is remarkably improved than the traditional implicit sensitivity filter based on B-splines under successive global refinement; and c) the generated black and white designs are preliminarily compatible with current commercial computer aided design system. Several numerical examples are used to verify the effectiveness of the proposed implicit Heaviside filter in compliance and compliant mechanism as well as heat conduction TO problems.

关键词： topology optimization     truncated hierarchical B-spline     isogeometric analysis     black and white designs     Heaviside filter    

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标题 作者 时间 类型 操作

Impacts of backwashing on micropollutant removal and associated microbial assembly processes in sand

期刊论文

Numerical simulation of compaction parameters for sand-filled embankment using large thickness sand filling

Wentao WANG, Chongzhi TU, Rong LUO

期刊论文

Unified description of sand behavior

Feng ZHANG, Bin YE, Guanlin YE

期刊论文

Research review of the cement sand and gravel (CSG) dam

Xin CAI, Yingli WU, Xingwen GUO, Yu MING

期刊论文

Effects of microfine aggregate in manufactured sand on bleeding and plastic shrinkage cracking of concrete

Branavan ARULMOLY; Chaminda KONTHESINGHA; Anura NANAYAKKARA

期刊论文

Destructive and non-destructive evaluation of concrete for optimum sand to aggregate volume ratio

期刊论文

Effects of coarse and fine aggregates on long-term mechanical properties of sea sand recycled aggregate

期刊论文

Performance of fiber reinforced clayey sand composite

Amin CHEGENIZADEH, Hamid NIKRAZ

期刊论文

The coupling of sand with ZVI/oxidants achieved proportional and highly efficient removal of arsenic

Sana Ullah, Xuejun Guo, Xiaoyan Luo, Xiangyuan Zhang, Yameng Li, Ziyu Liang

期刊论文

Effect of microlimestone on properties of self-consolidating concrete with manufactured sand and mineral

Fulin Qu, Wengui Li, Xiaohui Zeng, Zhiyu Luo, Kejin Wang, Daichao Sheng

期刊论文

Utilization of MSWI fly ash as partial cement or sand substitute with focus on cementing efficiency and

Lei Zheng, Xingbao Gao, Wei Wang, Zifu Li, Lingling Zhang, Shikun Cheng

期刊论文

掺砂率及初始干密度对改良膨胀土无荷膨胀率影响研究

杨俊,杨志,张国栋,唐云伟,陈红萍

期刊论文

Evaluation of soil microbial toxicity of waste foundry sand for soil-related reuse

Haifeng ZHANG, Lu SU, Xiangyu LI, Jiane ZUO, Guangli LIU, Yujue WANG

期刊论文

Compressive behavior and microstructure of concrete mixed with natural seawater and sea sand

期刊论文

Implicit Heaviside filter with high continuity based on suitably graded THB splines

期刊论文