摘要：
To investigate crack propagation and the coalescence mechanism of a rock bridge under unloading condition induced by intensive excavation of rock mass, the direct shear test with unloading normal stress and corresponding particle flow code (PFC) simulation were conducted on the sandstone specimen containing a parallel fissure pair considering different fissure inclinations (varied from 0 degrees to 90 degrees) and initial shear stresses (varied from 4 to 7 MPa). Three failure patterns (i.e., shear failure, tensile failure, and tensile-shear mixed failure) are identified as experimental and numerical results. The failure pattern transforms in the order of a shear, tensile, and tensile-shear mixed failure pattern as the fissure inclination increases. Three displacement field types are summarized and correspond to different failure patterns. Comparing the shear strength, cracking process, and microscopic displacement field in the direct shear test with unloading normal stress and the conventional direct shear test, normal unloading weakens the shear strength of the specimen under the selected stress conditions (initial normal stress is 20 MPa, initial shear stress ranges from 4 to 7 MPa). Rebound deformation in the process of unloading promotes the high proportion of tensile cracks for the tested fissure inclinations.
摘要：
Hot stamping (or press hardening) is a new technology that is widely used in the production of advanced high-strength steel parts for automotive applications. Electrochemical measurements, including potentiodynamic polarization and electrochemical impedance spectroscopy (EIS), and accelerated corrosion tests (the neutral salt spray test and periodic immersion test) were conducted on press-hardened samples produced from uncoated (cold-rolled and cold strip production (CSP) hot-rolled) and Al-Si-coated press-hardened steels to elucidate their distinct anti-corrosion mechanisms. The cross-sectional micromorphology and element distribution of three types of press-hardened steels after a neutral salt spray test were observed using scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDAX). The corrosion resistance of Al-Si-coated press-hardened steel was found to be significantly diminished following the hot stamping process due to the presence of microcracks and elevated iron content in the coating subsequent to austenitizing heat treatment. On the other hand, the corrosion resistance of uncoated press-hardened sheets produced from cold-rolled and CSP hot-rolled press-hardened steel was found to be proximal due to their nearly identical composition and microstructure (fully martensite) after the hot stamping process. Considering the high efficiency and energy-saving properties of hot-rolled press-hardened steel, it holds the potential to replace cold-rolled and even aluminum-silicon-coated press-hardened steel in automobile manufacturing.
通讯机构：
[Huang, D ] C;Changan Univ, Coll Geol Engn & Geomat, Xian 710054, Peoples R China.
关键词：
Discontinuity;Shear behavior;Failure pattern;Unloading normal stress;Shear strength criteria
摘要：
The shear mechanical behavior of discontinuities under unloading conditions induced by intensive rock mass excavation differs from that under loading conditions. Therefore, the mechanical parameters obtained from the conventional direct shear test cannot effectively be used to assess the stability of excavated rock masses. To solve this problem, we conducted a series of experiments on saw-toothed discontinuities with different undulating angles and initial shear stresses under unloading normal stress with constant shear stress. The test results showed that the shear pattern transformed from climbing to climbing-gnawing and then to gnawing patterns as the undulating angle and initial shear stress increased. The shear stress remained stable with increasing shear displacement after instability in the climbing pattern, decreased with fluctuations in the climbing-gnawing pattern, and dropped steeply in the gnawing pattern. A negative linear correlation exists between the unloading magnitude and the initial shear stress. Unloading normal stress promoted deformation rebound and sawtooth damage, reducing the mobilizing shear strength. Modified Patton and Barton shear strength criteria considering the undulating angle, initial stress, and failure pattern under unloading normal stress were proposed. The shear mechanical behavior of saw-toothed discontinuities with different undulating angles and initial shear stresses under unloading normal stress with constant shear stress are investigated.The failure pattern changes from the climbing pattern to the climbing-gnawing pattern and then to the gnawing pattern as the undulating angle and the initial shear stress increase.Unloading promotes the increase in rebound deformation and the area of the damage zone, leading to the decrease in shear strength of saw-toothed discontinuities.The modified Patton criterion and the Barton criterion are proposed for unloading normal stress considering the undulating angle, initial stress state, and failure pattern.
关键词：
Disodium hydrogen phosphate dodecahydrate;Diatomite;Composite phase change material;Building energy conservation;Corrosion test of reinforcing steel bar
摘要：
By combining inorganic hydrated salt phase change materials (PCMs) with traditional building materials, new multifunctional building materials are prepared, which can achieve energy optimization of building envelope structures and improve indoor thermal comfort. This study chose disodium hydrogen phosphate dodecahydrate (DHPD) as PCM and 4 % Na2SiO3.9H(2)O as the nucleating agent to prepare a modified PCM with extremely low supercooling degree (0.3 C). Then, the modified PCM was introduced into 45 % diatomite to gain a composite PCM (CPCM) with a melting temperature of 30.4 C, a melting enthalpy of 130.1 J/g, and a thermal conductivity of 0.24 W m(-1) K-1 by melt mixing method, being suitable for building insulation. The corrosion test of steel bar showed the introduction of diatomite can solve the corrosion problem of reinforcing steel bar by DHPD. The results of SEM, pore structure analysis, FT-IR and XRD illustrated that the pores and disc surfaces of diatomite were almost covered by the modified PCM, and that were combination between the diatomite and PCM was a physical interaction. After 200 cold -heating cycles, the melting temperature change of the CPCM was less than 3 % with the loss of melting enthalpy of only 4.7 %, indicating its good thermal stability. In addition, the CPCM was filled into polycarbonate hollow panels to produce PCM board, and its temperature regulation performance was evaluated through two experimental rooms. The results showed that the thermal comfort time of the room equipped with PCM board accounted for 47.46 %, which was 40.09 % higher than that of (7.37 %) the one without PCM board, presenting a better building energy -saving effect. Therefore, the prepared CPCM has broad application prospect in the building energy conservation.
摘要：
This study proposed a new curing agent consisting of slag and desulfurization gypsum industrial waste to solidify Cr(VI)-contaminated soils and prevent its migration and bioaccumulation in the ecosphere. The curing agent dosage of 10-30% resulted in a Cr(VI) toxic leaching concentration, compressive strength, and hydraulic conductivity range of 0.118-5.824 mg/L, 2.70-10.22 MPa, and 1.70 x 10-9-1.37 x 10-6 cm/s, respectively. Following four dry and wet cycles, the dosage of the curing agent was found to be 20-30% to achieve minimum environmental safety requirements. Cr(VI) in the cured specimens mainly existed as CrO42-, or acid salt, in which a portion was changed to Cr(III) during precipitation or directly was encased in the silica-alumina mesh structure. The adsorption capacity of hexavalent chrome on the outer of the hydration product groups was insignificant owing to the electronegativity. Hence, the Cr(VI) was solidified by hydrides such as C-S(A)-H and calcium alumina inclusions. Calcite, quartz, and several zeolite-like substances were also found to be colloidal in the pores to block Cr(VI).
摘要：
In the practical operation of traditional landfills, compaction clay often experiences cracking, while the HDPE geomembrane may tear and bulge, resulting in a compromised performance of the landfill covering system. To address this issue, a capillary retarding covering material for landfill sites is proposed by utilizing municipal sludge and construction waste particles as substrates and incorporating a small quantity of calcium bentonite. The mechanical characteristics of the covering material were investigated using a standard consolidation test and a triaxial compression test. A permeability test and a soil water characteristic curve (SWCC) test were conducted to examine the permeability and capillary retarding effect of the covering material. Microscopic tests including SEM scanning, laser particle size analysis, and T2 NMR analysis were performed to investigate the connection mode, particle size composition, and pore structure characteristics of the covered particles. Based on the aforementioned research, the following conclusions can be drawn: The cohesion of the covering material ranged from 50 to 150 kPa, while the internal friction angle ranged from 24.23 degrees to 31 degrees. The cohesion was directly proportional to the content of construction waste, whereas the internal friction angle was inversely proportional to calcium bentonite content. The permeability coefficient ranged from 5.04 x 10-6 cm/s to 7.34 x 10-5 cm/s, indicating a certain level of impermeability. Both the sludge and the calcium bentonite contents jointly influenced the final permeability coefficient in a negative correlation manner, with a notable hydraulic hysteresis phenomenon observed. A higher content of construction waste leads to a more pronounced supporting force exerted by the formed skeleton structures within a load pressure range between 0 and 1600 kPa. When considering a mass ratio of municipal sludge: construction waste: calcium bentonite as 30:60:7, respectively, only a decrease in the pore ratio by approximately 13.20% was observed. This study provides valuable data support for designing and applying capillary retarding cover barrier systems in landfills.
摘要：
A green and sustainable approach was employed to synthesize N, O-codoped porous carbon nanorods with two-end-open characteristics. In this method, a crab shell was utilized as a template and activator, while egg white served as a carbon precursor. The resulting carbon nanorods sintered at 700 degrees C (CNRs-700), exhibited cross-linked pore channels, a high surface area, and abundant defects and active sites. These features imparted superior energy storage properties to the material, enabling its application as both an anode for lithium-ion batteries and a supercapacitor. The CNRs-700 demonstrated an exceptional lithium storage capacity of 530.6 mAh g(-1) at 2 A g(-1), corresponding to 90.1% of the capacity achieved at 100 mA g(-1), which is ascribed to the pseudocapacitive contribution. Furthermore, in an evaluation combining a three-electrode configuration in KOH electrolyte at a high current density of 50 A g(-1), the CNRs-700 retained a specific capacitance of 140 F g(-1). For symmetrical supercapacitors based on CNRs-700 in 1 M Na2SO4 electrolyte, the energy density reached 27.1 Wh kg(-1) at a 375 W kg(-1) power density, demonstrating remarkable cyclability over 10,000 consecutive cycles. The superior rate performance and cycling stability would accentuate the suitability of the biomass-derived carbon materials for such systems.
摘要：
Wet sewage sludge (WSS) self-moisture gasification is a promising route for H2-rich syngas production. This research investigated the co-gasification of WSS and corn stalks (CS), focusing on the effects of self-moisture content. Thermogravimetric analysis of the pyrolysis of the mixture (WSS:CS = 40:60 wt%) revealed that the reactions followed a three-parallel-reaction model. The co-gasification process was performed to compare the effects of self-moisture and external steam used as gasification agents, respectively. The results showed that the self-moisture gasification led to higher H2 yields (0.057–0.11 L/g), gas yields (0.19–0.21 L/g), and specific gas energy (2.62–2.72 MJ/kg) than those in external steam gasification (0.055–0.090 L/g, 0.16–0.18 L/g and 2.32–2.52 MJ/kg, respectively). Additionally, self-moisture gasification also resulted in lighter tar with primarily light organic acids (28.0%), and char with weaker aromatic structure features, attributed to longer reaction time during diffusion of pyrolysis products. Overall, this study provided theoretical foundations for the high-value exploitation of WSS.
期刊：
Journal of Hazardous Materials,2024年465:133198 ISSN：0304-3894
通讯作者：
Lan, JR
作者机构：
[Pan, Cong; Lan, Jirong; Hou, Haobo] Wuhan Univ, Sch Resource & Environm Sci, Wuhan 430072, Peoples R China.;[Lan, Jirong; Sun, Yan; Kai, Ming-Feng] Hong Kong Polytech Univ, Dept Civil & Environm Engn, Hong Kong, Peoples R China.;[Dong, Yiqie] Wuhan Polytech Univ, Sch Civil Engn & Architecture, Wuhan 430023, Peoples R China.
通讯机构：
[Lan, JR ] W;Wuhan Univ, Sch Resource & Environm Sci, Wuhan 430072, Peoples R China.
关键词：
Amorphous structure;CSWR/PMS system;Carbamazepine;Copper tailing;High value application
摘要：
It is a green and sustainable path to establish cheap solid waste-based catalyst to establish peroxymonosulfate (PMS) catalytic system for the degradation of carbamazepine (CBZ) in water. In this study, durable copper tailing waste residue-based catalyst (CSWR) was prepared, and efficient CSWR/PMS system was constructed for catalytic degradation of CBZ for first time. The morphology and structure of CSWR changed from clumps to porous and loose amorphous by alkali leaching and medium temperature calcination. The reconstructed surface of the CSWR exposes more active sites promotes the catalytic reaction and increases the degradation rate of CBZ by more than 39.8 times. And the CSWR/PMS achieved a CBZ removal of nearly 99.99 % in 20min. In particular, perovskite-type iron-calcium compounds were formed, which stimulated the production of more HO(•) and SO(4)(•-) in the system. DFT calculation shows that CSWR has stronger adsorption energy and electron transfer ability to PMS molecules, which improved the degradation efficiency of the system. In general, this study proposed a means of high-value waste utilization, which provided a new idea for the preparation of solid waste based environmental functional materials and is expected to be widely used in practical wastewater treatment.
期刊：
Construction and Building Materials,2024年411:134273 ISSN：0950-0618
通讯作者：
Zheng, ZS;Huang, YJ
作者机构：
[Zeng, Chen] Wuhan Polytech Univ, Sch Civil Engn & Architecture, Wuhan 430023, Peoples R China.;[Liu, Gang; Wang, Xiang; Zheng, ZS; Zheng, Zhi-shan] Wuhan Municipal Engn Design & Res Inst Co Ltd, Wuhan 430023, Peoples R China.;[Zhang, Hui; Huang, Yu-jie] North Univ China, Sch Environm & Safety Engn, Taiyuan 030051, Peoples R China.
通讯机构：
[Zheng, ZS ] W;[Huang, YJ ] N;Wuhan Municipal Engn Design & Res Inst Co Ltd, Wuhan 430023, Peoples R China.;North Univ China, Sch Environm & Safety Engn, Taiyuan 030051, Peoples R China.
关键词：
Non-uniform corrosion of steel;3D mesoscale model;Mass transfer;Electrochemical corrosion;Bi-directional erosion
摘要：
Chloride-induced corrosion of steel in reinforced concrete (RC) exhibits complicated mechanisms such as chlo-ride diffusion, oxygen diffusion, electrochemical polarization, dissolution and deposition of steel. This work investigates the 3D non-uniform corrosion behavior of steel in RC by integrating all the possible mechanisms and mesoscale heterogeneities, for the first time. The anodic Tafel slope is used to describe the depassivation of steel induced by chloride, while the dynamic process of oxygen supply and consumption is considered as well as the inhibition of the cathodic reaction caused by oxygen concentration. The coupling of mass transfer and electro-chemical corrosion in RC is developed and validated. Mesoscale RC models with realistic aggregate, mortar, steel and interface are generated through a physically-based approach similar to casting procedures. The simulation results show that the 3D mesoscale RC model can simultaneously capture the non-uniform corrosion patterns of steel along the circumferential and longitudinal directions, offering significant application value in accurately predicting steel corrosion morphology. The random distribution of aggregates affects the local non-uniform corrosion of steel, but has little influence on the overall cumulative corrosion level. The local non-uniform corrosion of steel gradually weakens with the increase in chloride erosion time. The non-uniform corrosion of side steel is enhanced with the increase of the steel diameter and the decrease of the protective layer thickness. Bi-directional erosion mainly enhances the uniform corrosion of corner steel.
摘要：
Quicklime (CaO) or reactive magnesia (MgO) could be utilized as a novel activator of ground granulated blast-furnace slag (GGBS) to produce the geopolymer. The geopolymer was used to solidify soft soil, showing a significant environmental benefit over conventional Portland cement. In this study, the geopolymers were made according to the weight ratio of CaO/MgO to GGBS of 1:9 and 2:8 and were further used to solidify silty clay. The engineering and microstructural characteristics of the solidified silty clay were investigated through various physicochemical, mechanical, and microscopic tests. The results indicated that the unconfined compressive strength of the solidified specimens increased with the increase of activator ratio and curing period. The CaO-GGBS (CG)-solidified soil had a higher unconfined compressive strength than the MgO-GGBS (MG)-solidified soil after 7-day curing, while the MG-solidified soil showed good mechanical properties in the long run. The pH and electrical conductivity of the solidified soils gradually decreased with the decreasing binder dosage and the increasing curing period, and these values of MG-solidified soils were lower than those of CG-solidified soils. Based on XRD analysis, the CSH and hydrotalcite were confirmed to be the main hydration product of both CG/MG-solidified soils in filling the large pores, and the reinforcement mechanism model for the soil treated with CG/MG geopolymers was also proposed. The research results demonstrated that CG/MG geopolymers can be used as a binder to solidify soft soils.
关键词：
train operation;vibration;construction stage;transfer function;finite element model
摘要：
In response to land use challenges, major urban centers have started implementing over-track building constructions above metro lines as a means of accommodating residents and workers. However, the continuous operation of trains can generate excessive vibrations that may negatively impact the overall living conditions for occupants residing in these structures. In this paper, vibration measurements were conducted on the soil and within a three-story frame structure building. Additionally, a three-dimensional finite element model of the track-soil-building was established. The wheel-rail contact force was incorporated as a dynamic load that varies with time to accurately simulate the vibration response induced by trains. According to the construction process of the over-track building, four construction stages were set up using the finite element model to study the impact of the construction stages on the vibration propagation from the soil to building structure. The results indicate that the presence of existing structures exerts a mitigating influence on soil vibrations. Pile foundation construction can effectively mitigate soil vibration to a significant extent. The findings provide references for the future development and design of over-track buildings.
摘要：
Surface wave dispersion curves are widely used to constrain earth velocity structures and are important to compute theoretical synthetic seismograms with a mode-summation approach. While the computation of dispersion curves requires searching roots of nonlinear functions, some high-mode may be missed with improper choice of searching steps. The asymptotic distribution of eigenvalues of the elastic wave equation can be used as auxiliary information to design a sophisticated scheme to compute the surface wave dispersion curves. In this study, we show the Weyl’s law, combined with the Liouville transformation, can be exploited to derive asymptotic eigenvalue counting functions of elastic surface waves in a horizontally stratified or radially heterogeneous medium. We also show the derived formulation according to the Weyl’s law, in its simple case, agrees with previous studies. The derived asymptotic eigenvalue counting functions are validated by comparison with numerical results. This study demonstrates the Weyl’s law can be used to derive eigenvalue counting functions of surface waves in elastic media, and it is also possible to be applied to more complex media.
摘要：
In this study, Enzyme-Induced Carbonate Precipitation (EICP) combined with polypropylene fiber technology was used to solidify desert sand, the orthogonal theory was used to design the different levels of the five test variables of cementation solution concentration, urease concentration, enzyme gel ratio, fiber length and fiber content, and the curing effect of EICP combined with polypropylene fiber was studied by macroscopic test of unconfined compressive strength and calcium carbonate content and microscopic test of scanning electron microscope (SEM) and nuclear magnetic resonance (NMR). The results show that the primary and secondary order of the influence of the five test variables on the unconfined compressive strength and calcium carbonate content is: fiber content >fiber length >urease concentration >enzyme gel ratio >cementation solution concentration, in which the fiber length and fiber content had a significant effect on it, and the urease concentration had a little significant effect on it. The incorporation of polypropylene fiber promotes the deposition of calcium carbonate, restricts the displacement and deformation of sand particles, effectively fills the pores between particles, significantly reduces the pore size, and improves the pore structure, which provides a reference for subsequent research and practical geotechnical applications.
期刊：
Journal of Marine Science and Engineering,2024年12(3):522- ISSN：2077-1312
通讯作者：
Xu, H
作者机构：
[Peng, Daicheng] Yangtze Univ, Key Lab Explorat Technol Oil & Gas Resource, Minist Educ, Wuhan 430100, Peoples R China.;[Cheng, Fei] China Univ Geosci, Hubei Key Lab Marine Geol Resources, Wuhan 430074, Peoples R China.;[Xu, Hao; Xu, H] Wuhan Polytech Univ, Sch Civil Engn & Architecture, 68 Xuefu South Rd, Wuhan 430023, Peoples R China.;[Zong, Yuquan] Cent Southern China Elect Power Design Inst Co Ltd, China Power Engn Consulting Grp, Wuhan 430071, Peoples R China.
通讯机构：
[Xu, H ] W;Wuhan Polytech Univ, Sch Civil Engn & Architecture, 68 Xuefu South Rd, Wuhan 430023, Peoples R China.
关键词：
coastal engineering exploration;multi-wave and multi-component;cross-well seismic exploration;3D reverse time migration imaging;elastic wave decomposition
摘要：
Precise surveys are indispensable in coastal engineering projects. The extensive presence of sand in the coastal area leads to significant attenuation of seismic waves within unsaturated loose sediments. As a result, it becomes challenging for seismic waves to penetrate the weathered zone and reach the desired depth with significant amount of energy. In this study, the application of three-dimensional (3D) cross-well elastic reverse time migration (RTM) imaging based on multi-wave and multi-component techniques in coastal engineering exploration is explored. Accurate decomposition of vector compressional (P) and shear (S) waves is achieved through two wavefield decoupling algorithms without any amplitude and phase distortion. Additionally, compressional wave pressure components are obtained, which facilitates subsequent independent imaging. This study discusses and analyzes the imaging results of four imaging strategies under cross-correlation imaging conditions in RTM imaging. The analysis leads to the conclusion that scalarizing vector wavefields imaging yields superior imaging of P- and S-waves. Furthermore, the imaging results obtained through this approach are of great physical significance. In order to validate the efficacy of this method in 3D geological structure imaging in coastal areas, RTM imaging experiments were performed on two representative models. The results indicate that the proposed 3D elastic wave imaging method effectively generates accurate 3D cross-well imaging of P- and S-waves. This method utilizes the multi-wave and multi-component elastic wave RTM imaging technique to effectively leverage the Earth’s elastic medium without increasing costs. It provides valuable information about the distribution of subsurface rock layers, interfaces, and other structures in coastal engineering projects. Importantly, this can be achieved without resorting to extensive excavation or drilling operations. This method addresses the limitations of current cross-well imaging techniques, thereby providing abundant and accurate geological and geophysical information for the analysis and interpretation of 3D geological structures in coastal engineering projects. It has important theoretical and practical significance in real-world production, as well as for the study of geological structures in coastal engineering.
摘要：
Purpose
The purpose of this paper is to develop a high-performance composite emulsion cement waterproof coating. The coating has excellent durability and is effective in protecting cement mortar substrates from harmful ions.
Design/methodology/approach
The polymer cement waterproof coatings with different emulsion compounding ratios were tested for mechanical properties and water resistance after alkali immersion, water immersion, thermal aging and UV aging, and the coatings were analyzed by infrared spectroscopy after aging to evaluate its durability. Meanwhile, the coating that presents favorable durability was applied to cement mortar test blocks. The protective effect of the coating on the test blocks was tested by immersion method, and X-ray diffraction analysis was performed on the eroded test blocks.
Findings
The coating with neoprene latex/acrylate latex weight ratio of 90/10 presents favorable durability and has superior overall performance. Besides, when it is applied to cement mortar blocks, the coatings effectively reduced the erosive effect of harmful ions on cement mortar blocks, resulting in much lower mass change ratios and less internal structural damage of the blocks significantly.
Originality/value
The obtained coating will be of great application potential for use in building waterproofing construction. Moreover, the coating can practically prevent chloride ions and sulfate ions from penetrating cement-based materials.
摘要：
Elemental doping has been widely employed to manipulate the electrical and thermal transport properties of thermoelectric materials, without considering the influence to mechanical properties. In skutterudites, electronegative S-dopants have been found to reduce the lattice thermal conductivity. However, the effect of the covalent S-Sb bond on the mechanical properties of CoSb3 skutterudites remains unexplored. Compressive strength, in particular, exhibits a significant reduction in S-doped skutterudites, measuring only 249 MPa, representing a nearly 50% decrease compared to binary skutterudites. Additionally, there is a noticeable drop in the elastic, bulk and shear modulus. With molecular dynamics calculations, the shear strength of S-doped skutterudites also follows a sharp drop at a small ultimate strain. The evolutions of atomic configurations reveal that the lattice strain induced by S-dopants softens the Sb-Sb bond, ultimately leading to structure collapse under low shear stress conditions. These findings underscore the necessity for a comprehensive approach to elemental doping in thermoelectric community.
期刊：
Computer Methods in Applied Mechanics and Engineering,2024年424:116899 ISSN：0045-7825
通讯作者：
Zhang, H;Natarajan, S
作者机构：
[Zhang, Hui; Zhang, H; Huang, Yu-jie] North Univ China, Sch Environm & Safety Engn, Taiyuan 030051, Peoples R China.;[Zheng, Zhi-shan] Wuhan Municipal Engn Design & Res Inst Co Ltd, Wuhan 430023, Peoples R China.;[Yao, Feng] PowerChina Huadong Engn Corp Ltd, Hangzhou 311122, Peoples R China.;[Zeng, Chen] Wuhan Polytech Univ, Sch Civil Engn & Architecture, Wuhan 430023, Peoples R China.;[Natarajan, S; Natarajan, Sundararajan] Indian Inst Technol Madras, Dept Mech Engn, Chennai 600036, India.
通讯机构：
[Natarajan, S ] I;[Zhang, H ] N;North Univ China, Sch Environm & Safety Engn, Taiyuan 030051, Peoples R China.;Indian Inst Technol Madras, Dept Mech Engn, Chennai 600036, India.
关键词：
Quasi-brittle fracture;Cell-based smoothed finite element method;Phase field cohesive zone model;Polygon discretization;Mesoscale concrete
摘要：
In recent years, engineering and research communities have shown a growing interest in polygon elements due to their adaptability to complex geometries. However, their applicability for investigating the quasi-brittle damage and fracture of concrete structures is still an open question. This work thus develops a numerical framework to integrate the phase-field regularized cohesive zone model (PFCZM) with the cell-based smoothed finite element method (CSFEM) using arbitrary polygon elements. The techniques of centroidal Voronoi tessellation and polytree decomposition are adopted to discretize the computational domains and efficiently refine the potential cracking areas in a multi-level manner. This allows fast transition of the mesh density and direct elimination of the hanging-node issue using the CSFEM. To calculate the displacements and the damage variables, only Wachspress shape functions and boundary geometries are needed, eliminating the need for coordinate mapping and Jacobian inversion. For each CSFEM subcell, crack-driving forces are determined at the integration point and stored as history variables. Typical concrete structures under different loading conditions are validated with respect to the crack path and load-carrying capacity, exhibiting good coarse-mesh accuracy. A mesoscale test-piece under uniaxial tension is also modelled using the developed framework, showing significant computational efficiency when compared to the conventional FEM.
期刊：
Chemical Engineering Journal,2024年482 ISSN：1385-8947
通讯作者：
Hou, HB;Lan, JR
作者机构：
[Cai, Yungao; Hou, Haobo; Xiang, Yuwei] Wuhan Univ, Sch Resource & Environm Sci, Wuhan, Peoples R China.;[Lan, Jirong] Hong Kong Polytech Univ, Dept Civil & Environm Engn, Hong Kong, Peoples R China.;[Dong, Yiqie] Wuhan Polytech Univ, Sch Civil Engn & Architecture, Wuhan, Peoples R China.
通讯机构：
[Lan, JR ] H;[Hou, HB ] W;Wuhan Univ, Sch Resource & Environm Sci, Wuhan, Peoples R China.;Hong Kong Polytech Univ, Dept Civil & Environm Engn, Hong Kong, Peoples R China.
关键词：
Nickel tailings;PMS-AOPs;Active radicals;Crystallographic plane;Density functional theory
摘要：
The use of nickel-cobalt tailings rich in nickel, cobalt, and iron to produce catalytic materials that drive advanced oxidation systems for PMS is a sustainable strategy. This study uses a combination of alkali modification and calcination to prepare a novel waste-based PMS-AOPs catalytic material (NCT-beta), and its catalytic activity against organic pollutants (RB-19, BPA, RhB, SMX, CBZ, and BA) was investigated under the activation of PMS, for first time. The characterization results showed that NCT-beta was modified into a multi-layer honeycomb with irregular surface, which can provide abundant active sites for chemical reactions, and expose metal elements on the surface of the material, promoting the electron transfer efficiency of organic pollutant degradation. The degradation rate of NCT-beta to RB-19 was 98.26 % within 30 min, and the catalytic efficiency was still more than 80 % when repeated use. Free radical pathway dominates the degradation process of organic pollutants, 1O2, & sdot;O2, and & sdot;OH are the main active radicals. Density functional theory (DFT) results indicate that the (020) crystal plane exposed by NCT-beta is the strongest site of action for pollutants and PMS. This study provides a solution for developing green environmental functional materials based on solid waste and treating waste with waste.
