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Seismic response of precast reinforced concrete wall subjected to cyclic in-plane and constant out-of-plane loading

《结构与土木工程前沿（英文）》 2021年 第15卷 第5期   页码 1128-1143 doi: 10.1007/s11709-021-0753-5

摘要： This paper provides insight into the seismic behavior of a full-scale precast reinforced concrete wall under in-plane cyclic loading combined with out-of-plane loading replicated by sand backfill to simulate the actual condition of basement walls. The tested wall exhibited flexural cracks, owing to the high aspect ratio and considerable out-of-plane movement due to lateral pressure from the backfill. The wall performed satisfactorily by exhibiting competent seismic parameters and deformation characteristics governed by its ductile response in the nonlinear phase during the test with smaller residual drift. Numerical analysis was conducted to validate experimental findings, which complied with each other. The numerical model was used to conduct parametric studies to study the effect of backfill density and aspect ratio on seismic response of the proposed precast wall system. The in-plane capacity of walls reduced, while deformation characteristics were unaffected by the increase in backfill density. An increase in aspect ratio leads to a reduction in in-plane capacity and an increase in drift. Curves between the ratio of in-plane yield capacity and design shear load of walls are proposed for the backfill density, which may be adopted to determine the in-plane yield capacity of the basement walls based on their design shear.

关键词： precast wall     basement wall     out-of-plane response     quasi-static test     sand backfill     seismic parameters    

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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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Upper bound solution to seismic active earth pressure of submerged backfill subjected to partial drainage

《结构与土木工程前沿（英文）》 2021年 第15卷 第6期   页码 1480-1493 doi: 10.1007/s11709-021-0776-y

摘要： In waterfront geotechnical engineering, seismic and drainage conditions must be considered in the design of retaining structures. This paper proposes a general analytical method to evaluate the seismic active earth pressure on a retaining wall with backfill subjected to partial steady seepage flow under seismic conditions. The method comprises the following steps: i) determination of the total head, ii) upper bound solution of seismic active earth thrust, and iii) deduction for the earth pressure distribution. The determination of total head h(x,z) relies on the Fourier series expansions, and the expressions of the seismic active earth thrust and pressure are derived by using the upper bound theorem. Parametric studies reveal that insufficient drainage and earthquakes are crucial factors that cause unfavorable earth pressure. The numerical results confirm the validity of the total head distribution. Comparisons indicate that the proposed method is consistent with other relevant existing methods in terms of predicting seismic active earth pressure. The method can be applied to the seismic design of waterfront retaining walls.

关键词： seismic active earth pressure     partial seepage flow     pore pressure     anisotropy     upper bound theorem    

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temperature-dependence of compressive and tensile behaviors of polypropylene fiber-reinforced cemented paste backfill

《结构与土木工程前沿（英文）》 2021年 第15卷 第4期   页码 1025-1037 doi: 10.1007/s11709-021-0741-9

摘要： The understanding of compressive and tensile behaviors of polypropylene fiber-reinforced cemented paste backfill (FR-CPB) play crucial roles in the successful implementation of reinforcement technique in underground mine backfilling operations. However, very limited studies have been performed to gain insight into the evolution of compressive and tensile behaviors and associated mechanical properties of FR-CPB under various curing temperatures from early to advanced ages. Thus, this study aims to investigate the time (7, 28, and 90 d)- and temperature (20°C, 35°C, and 45°C)-dependence of constitutive behavior and mechanical properties of FR-CPB. The obtained results show that pre- and post-failure behaviors of FR-CPB demonstrate strongly curing temperature-dependence from early to advanced ages. Moreover, the pseudo-hardening behavior is sensitive to curing temperature, especially at early ages. Furthermore, the mechanical properties including elastic modulus, material stiffness, strengths, brittleness, cohesion, and internal friction angle of FR-CPB show increasing trends with curing temperature as curing time elapses. Additionally, a predictive model is developed to capture the strong correlation between compressive and tensile strength of FR-CPB. The findings of this study will contribute to the successful implementation of FR-CPB technology.

关键词： cemented paste backfill     fiber reinforcement     constitutive behavior     temperature     tailings    

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investigation of evolutive mode-I and mode-II fracture behavior of fiber-reinforced cemented paste backfill

《结构与土木工程前沿（英文）》 2023年 第17卷 第2期   页码 256-270 doi: 10.1007/s11709-022-0924-z

摘要： The curing temperature-dependent cement hydration causes the nonlinear evolution of fracture behavior and properties of fiber-reinforced cemented paste backfill (CPB) and thus influences the stability of mine backfill materials in deep mines. Therefore, the coupled effect of curing temperature (20, 35, and 45 °C) and cement hydration at different curing times (3, 7, and 28 d) on the mode-I and mode-II fracture behavior and properties of fiber-reinforced CPB is investigated. A comprehensive experimental testing program consisting of semicircular bend tests, direct shear tests, measurement of volumetric water content and matric suction, TG/DTG tests, and SEM observation is carried out. The results show that the coupled thermochemical effect results in strongly nonlinear development of pre- and post-peak behavior of fiber-reinforced CPB. Moreover, the results discover a positive linear correlation between fracture toughness and shear strength parameters and also reveal the vital role played by matric suction in the formation of fracture toughness. Furthermore, predictive functions are developed to estimate the coupled thermochemical effect on the development of KIc and KIIc. Therefore, the findings and the developed mathematical tools have the potential to promote the successful application of fiber-reinforced CPB technology in deep underground mines.

关键词： fiber reinforcement     cemented paste backfill     fracture behavior     underground mine     cement hydration    

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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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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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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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标题 作者 时间 类型 操作

Seismic response of precast reinforced concrete wall subjected to cyclic in-plane and constant out-of-plane loading

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

Upper bound solution to seismic active earth pressure of submerged backfill subjected to partial drainage

期刊论文

temperature-dependence of compressive and tensile behaviors of polypropylene fiber-reinforced cemented paste backfill

期刊论文

investigation of evolutive mode-I and mode-II fracture behavior of fiber-reinforced cemented paste backfill

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

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

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