摘要：
The energy consumption of buildings in China's hot-summer and cold-winter regions is high, and building envelope structures urgently require further optimization. Research on optimizing building envelope structures with phase-change material (PCM) typically assumes a continuous air-conditioning operation mode, however, in China, air conditioning often operates intermittently. Considering the changes in the specific heat capacity and thermal conductivity during the PCM phase transformation, this study compares the thermal performance and energy consumption of phase-change concrete wall (PCCW) and ordinary concrete wall (OCW) under different air-conditioning modes. The findings reveal that, under intermittent air-conditioning operations 1) PCCW reduces the maximum internal surface temperature by 0.40 degrees C, delays the peak temperature by 15 min and 2) the indoor temperature distribution in PCCW is more uniform than in OCW, and after turning on the air conditioning, the time required for the indoor temperature to drop to the set temperature decreases by 31.50%. Moreover, buildings with a PCCW as the external wall exhibits an annual energy consumption reduction of 20.32%. This study analyzes the heat-transfer characteristics of PCCW in hot-summer and cold-winter regions and their impact on energy consumption, offering a reference for the promotion and application of phase-change walls.
摘要：
The reasonable determination of correlation distances serves as the prerequisite for ensuring the accuracy of random field simulation results for geotechnical parameters, and also constitutes a critical challenge in random field simulations that remains difficult to resolve. The Bootstrap method was employed to perform resampling on correlation distances. Utilizing the sampling results, a weighted prior probability density function for correlation distances was constructed. By applying Bayesian principles in conjunction with Hoffman's conditional random field simulation method, the decoupling and simultaneous updating of correlation distance determinations and geotechnical parameter estimations in random field simulations were achieved. Taking a seabed site as an example, this study simulated the spatial variability of marine soil SPT- N values and their influence on seabed liquefaction probability. The research revealed the impacts of correlation distances, constraints from measured borehole data, and heterogeneity of original site stratigraphy on random field simulation outcomes and seabed liquefaction probability. The validity of the proposed methodology was confirmed through verification against reserved measurement results at actual borehole locations.
The reasonable determination of correlation distances serves as the prerequisite for ensuring the accuracy of random field simulation results for geotechnical parameters, and also constitutes a critical challenge in random field simulations that remains difficult to resolve. The Bootstrap method was employed to perform resampling on correlation distances. Utilizing the sampling results, a weighted prior probability density function for correlation distances was constructed. By applying Bayesian principles in conjunction with Hoffman's conditional random field simulation method, the decoupling and simultaneous updating of correlation distance determinations and geotechnical parameter estimations in random field simulations were achieved. Taking a seabed site as an example, this study simulated the spatial variability of marine soil SPT- N values and their influence on seabed liquefaction probability. The research revealed the impacts of correlation distances, constraints from measured borehole data, and heterogeneity of original site stratigraphy on random field simulation outcomes and seabed liquefaction probability. The validity of the proposed methodology was confirmed through verification against reserved measurement results at actual borehole locations.
期刊：
Process Safety and Environmental Protection,2025年201:107526 ISSN：0957-5820
通讯作者：
Xu, P
作者机构：
[Liu, Xin] Univ South China, Hunan Prov Key Lab Pollut Control & Resources Reus, Hengyang 421001, Peoples R China.;[Xu, Peng; He, Qiulai; Ma, Jingwei; Liu, Xin; Xu, P] Hunan Univ, Coll Civil Engn, Hunan Engn Res Ctr Water Secur Technol & Applicat, Changsha 410082, Peoples R China.;[Yu, Quan] Hunan Univ Sci & Technol, Sch Civil Engn, Hunan Prov Key Lab Shale Gas Resource Utilizat, Xiangtan 411201, Peoples R China.;[Zheng, Mengqi] Hefei Univ Technol, Sch Civil Engn, Dept Municipal Engn, Hefei 230009, Peoples R China.
通讯机构：
[Xu, P ] H;Hunan Univ, Coll Civil Engn, Hunan Engn Res Ctr Water Secur Technol & Applicat, Changsha 410082, Peoples R China.
关键词：
Tetracycline degradation;HA/Cl-/Cu 0 /H 2 O 2 system;Cu 2+/Cu + cycle;Hydroxyl radical and reactive chlorine species;CuClx1-x
摘要：
The process of hydrogen peroxide triggered by zero-valent copper (Cu 0 /H 2 O 2 ) was usually used to decompose organic pollutants . Nevertheless, its oxidation efficacy was restricted by the disproportionation of Cu⁺ along with the interaction between Cu⁺ and O₂. The research found that the combination of chloride ion (Cl − ) and hydroxylamine (HA) obviously enhanced the Cu 0 /H 2 O 2 process, and 87.1 % of tetracycline was degraded in 15 min. In the HA/Cl − /Cu 0 /H 2 O 2 process, on the one hand, the cycle of Cu 2+ /Cu + was persistently motivated by HA; On the other hand, Cl − reinforced the stability of Cu + by forming CuCl x 1-x complexants and promoted the synproportionation of Cu 0 and Cu 2+ with generating CuCl. The experiments of identifying reactive oxygen species found that hydroxyl radical and reactive chlorine species played a main role in decomposing tetracycline with its contribution ratios respectively being 83.8 % and 17.2 %. The final emission concentration of total dissolve copper was 11.1 μmol/L and met the national emission requirements after the conventional treatment, and the product of HA was ultimately discharged in the form of N 2 . These results revealed that the HA/Cl − /Cu 0 /H 2 O 2 system was an effective and eco-friendly.
The process of hydrogen peroxide triggered by zero-valent copper (Cu 0 /H 2 O 2 ) was usually used to decompose organic pollutants . Nevertheless, its oxidation efficacy was restricted by the disproportionation of Cu⁺ along with the interaction between Cu⁺ and O₂. The research found that the combination of chloride ion (Cl − ) and hydroxylamine (HA) obviously enhanced the Cu 0 /H 2 O 2 process, and 87.1 % of tetracycline was degraded in 15 min. In the HA/Cl − /Cu 0 /H 2 O 2 process, on the one hand, the cycle of Cu 2+ /Cu + was persistently motivated by HA; On the other hand, Cl − reinforced the stability of Cu + by forming CuCl x 1-x complexants and promoted the synproportionation of Cu 0 and Cu 2+ with generating CuCl. The experiments of identifying reactive oxygen species found that hydroxyl radical and reactive chlorine species played a main role in decomposing tetracycline with its contribution ratios respectively being 83.8 % and 17.2 %. The final emission concentration of total dissolve copper was 11.1 μmol/L and met the national emission requirements after the conventional treatment, and the product of HA was ultimately discharged in the form of N 2 . These results revealed that the HA/Cl − /Cu 0 /H 2 O 2 system was an effective and eco-friendly.
摘要：
Deep rock engineering (such as geothermal exploration, underground energy storage, radioactive waste storage) is often affected by external disturbances and high temperatures. Through characteristic stress identification, acoustic emission (AE) monitoring and numerical simulation, the deformation and fracture processes and degree of thermal-mechanical damaged sandstone are studied, and a simulation method considering thermal strengthening is proposed based on the two-dimensional particle flow code (PFC 2D ). The results show that: The axial peak strain of the sample shows fluctuations below 450 °C as temperature increases, and is followed by a rapid rise, whereas Poisson’s ratio, after reaching its maximum at 150 °C, gradually decreases. With the increase of damage degree, the mean values of σ cc / σ f and σ ci / σ f first decrease and then increase, while the mean values of σ cd / σ f have the opposite trend. With the increase of temperature, σ ci / σ f of sandstone increases, while σ cd / σ f remains at a certain level and fluctuates or decreases. Although the frequency band distribution and quantities of different rock samples are different, the frequency band number and the density within the frequency band have sudden changes before the samples are destroyed. The simulation results indicate that the porosity shows stress sensitivity and intergranular cracking dominates the failure process. The experimental and PFC simulation results agree well in terms of peak stress, failure mode and crack distribution, which verifies the applicability of the proposed thermal strengthening model.
Deep rock engineering (such as geothermal exploration, underground energy storage, radioactive waste storage) is often affected by external disturbances and high temperatures. Through characteristic stress identification, acoustic emission (AE) monitoring and numerical simulation, the deformation and fracture processes and degree of thermal-mechanical damaged sandstone are studied, and a simulation method considering thermal strengthening is proposed based on the two-dimensional particle flow code (PFC 2D ). The results show that: The axial peak strain of the sample shows fluctuations below 450 °C as temperature increases, and is followed by a rapid rise, whereas Poisson’s ratio, after reaching its maximum at 150 °C, gradually decreases. With the increase of damage degree, the mean values of σ cc / σ f and σ ci / σ f first decrease and then increase, while the mean values of σ cd / σ f have the opposite trend. With the increase of temperature, σ ci / σ f of sandstone increases, while σ cd / σ f remains at a certain level and fluctuates or decreases. Although the frequency band distribution and quantities of different rock samples are different, the frequency band number and the density within the frequency band have sudden changes before the samples are destroyed. The simulation results indicate that the porosity shows stress sensitivity and intergranular cracking dominates the failure process. The experimental and PFC simulation results agree well in terms of peak stress, failure mode and crack distribution, which verifies the applicability of the proposed thermal strengthening model.
摘要：
Most existing passive earth pressure theories are not completely suitable for the calculation of unsaturated backfill in practical engineering, especially for narrow backfill cases. In view of this, this study establishes a modified analytical model for the passive earth pressure of narrow backfill behind a retaining wall under unsaturated steady-state seepage conditions, based on the log-spiral failure mechanism and the arched differential element method. The distribution, total force magnitude, and the height of the application point of passive earth pressure for narrow backfill under the rotation about the wall toe (RB) mode are calculated by the fourth order Runge-Kutta method within the framework of the generalized effective stress principle. To validate the proposed method, a comparative analysis is conducted by integrating experimental, theoretical, and OptumG2 simulation results. Moreover, the effect of main parameters on passive earth pressures is investigated through a parametric analysis. The results show that as the wall-soil interface friction angle increases gradually, the passive earth pressure distribution curve transitions from convex towards the wall back to concave towards the wall back; with the increase of aspect ratio, the passive earth pressure curve gradually shifts from curved to nearly straight; with a small air entry pressure parameter, the total passive earth pressure force increases as the air entry pressure parameter increases, while the height of the application point of total force initially decreases and then increases; the hysteresis effect reduces the total passive earth pressure force and decreases the height of the application point of the total force.
摘要：
This study was conducted to investigate whether selected microbes with specific functions are comparable or even superior to indigenous consortium (IC) in the microbial uranium reduction process and to detect the immobilization mechanisms of U(VI) with different microbial consortia. Fe(III)-reducing bacteria (FeRB), sulfate-reducing bacteria (SRB) and nitrate-reducing bacteria (NRB) were employed to construct a designed consortium (DC), and the IC was obtained from natural samples. The results showed that the uranium-reducing ratio of the DC was higher (52.69 %) than that of the IC (35.65 %) after 34 days, although the uranium removal ratio with IC (98.75 %) was slightly higher than that of the DC (95.75 %). In both the DC and IC groups, uranium was first adsorbed onto the cell surface in the first few days, then sulfate and uranium were reduced simultaneously after depletion of nitrate, and finally labile U species transformed into stable form (e.g UO 2 ) over time. This work refined our understanding of the construction of highly efficient uranium-reducing microbes and provided insight into strengthening strategies for treating uranium-contaminated groundwater in situ .
This study was conducted to investigate whether selected microbes with specific functions are comparable or even superior to indigenous consortium (IC) in the microbial uranium reduction process and to detect the immobilization mechanisms of U(VI) with different microbial consortia. Fe(III)-reducing bacteria (FeRB), sulfate-reducing bacteria (SRB) and nitrate-reducing bacteria (NRB) were employed to construct a designed consortium (DC), and the IC was obtained from natural samples. The results showed that the uranium-reducing ratio of the DC was higher (52.69 %) than that of the IC (35.65 %) after 34 days, although the uranium removal ratio with IC (98.75 %) was slightly higher than that of the DC (95.75 %). In both the DC and IC groups, uranium was first adsorbed onto the cell surface in the first few days, then sulfate and uranium were reduced simultaneously after depletion of nitrate, and finally labile U species transformed into stable form (e.g UO 2 ) over time. This work refined our understanding of the construction of highly efficient uranium-reducing microbes and provided insight into strengthening strategies for treating uranium-contaminated groundwater in situ .
摘要：
Uranium-containing wastewater poses severe threats to ecological safety and human health, yet the development of adsorbents with both high adsorption capacity and strong selectivity remains a critical challenge in environmental remediation. In this study, a novel composite material (MX/PAN-AO-PA) was constructed by combining amidoxime and polyamine bifunctionalized PAN (PAN-AO-PA) with MXene via solution-phase synthesis for efficient uranium wastewater treatment. This design integrates the 2D layered structure of MXene with the selective uranium-binding groups of PAN-AO-PA, which synergistically enhances the surface area and uranium affinity. At 313 K, pH = 6 and C 0 = 80 mg·L −1 , MX/PAN-AO-PA exhibited a maximum adsorption capacity of 609.49 mg·g −1 for U(VI), approximately 250 % higher than that of pristine MXene (171.6 mg·g −1 ) with excellent selectivity. The adsorption behavior follows the pseudo-second-order kinetic model and Langmuir isotherm model. After 5 adsorption-desorption cycles, the uranium removal rate remained over 80 %, demonstrating good cyclic stability. FTIR and XPS analyses confirm that the efficient adsorption of U(VI) stems from the synergistic coordination of amidoxime groups (C(=NOH)NH 2 ) and polyamine groups (−NH 2 ), as well as the chelating effect of oxygen-containing functional groups (-OH, O ) on the MXene surface. This composite holds significant application value in radioactive wastewater treatment.
Uranium-containing wastewater poses severe threats to ecological safety and human health, yet the development of adsorbents with both high adsorption capacity and strong selectivity remains a critical challenge in environmental remediation. In this study, a novel composite material (MX/PAN-AO-PA) was constructed by combining amidoxime and polyamine bifunctionalized PAN (PAN-AO-PA) with MXene via solution-phase synthesis for efficient uranium wastewater treatment. This design integrates the 2D layered structure of MXene with the selective uranium-binding groups of PAN-AO-PA, which synergistically enhances the surface area and uranium affinity. At 313 K, pH = 6 and C 0 = 80 mg·L −1 , MX/PAN-AO-PA exhibited a maximum adsorption capacity of 609.49 mg·g −1 for U(VI), approximately 250 % higher than that of pristine MXene (171.6 mg·g −1 ) with excellent selectivity. The adsorption behavior follows the pseudo-second-order kinetic model and Langmuir isotherm model. After 5 adsorption-desorption cycles, the uranium removal rate remained over 80 %, demonstrating good cyclic stability. FTIR and XPS analyses confirm that the efficient adsorption of U(VI) stems from the synergistic coordination of amidoxime groups (C(=NOH)NH 2 ) and polyamine groups (−NH 2 ), as well as the chelating effect of oxygen-containing functional groups (-OH, O ) on the MXene surface. This composite holds significant application value in radioactive wastewater treatment.
摘要：
To enhance the engineering properties of granite residual soil for subgrade filling, cement is incorporated to improve the soil. Through compaction tests, direct shear tests, and scanning electron microscope (SEM) tests, the influence of adding different doses of cement on the shear strength, residual strength, and microstructure of granite residual soil is investigated. The experimental results show that the maximum dry density increases and the optimal moisture content decreases with increasing cement content up to 7%. The shear strength is significantly enhanced with the increase in cement content. This effect is mainly attributed to the significant improvement in soil cohesion due to the addition of cement. When the cement content exceeds 7%, the shear strength index still increases with the cement content, but the rate of change slows down significantly. The failure mode of improved soil exhibits brittle failure, with residual strength remaining unchanged after cement content reaches 3%. At lower stress levels, the residual strength of the improved soil is similar to the shear strength of the undisturbed granite residual soil; while at higher stress levels, the residual strength of the improved soil is inferior to the shear strength of the undisturbed granite residual soil. SEM images reveal that cement hydration products gradually fill pores, forming a continuous spatial network structure. Considering both effectiveness and economic factors, the optimal cement content is approximately 5%. These findings contribute to a deeper understanding of the engineering properties of cement-improved granite residual soil and provide guidance for related engineering construction.
摘要：
Given the fact that retaining structures in seismically active areas are key barriers for geotechnical engineering disaster prevention and mitigation, accurately assessing their seismic stability throughout their life cycle is an extremely important and urgent task. However, the traditional stability analysis method ignores the effect of suction stress, which results in a large discrepancy between the calculated results and the engineering practice. In view of this, this study derives the work-energy balance equation that is applicable to unsaturated soils within the framework of the generalized effective stress principle, and on this basis, proposes a method for calculating the coefficient of antislip stability of unsaturated retaining walls under seismic excitations by using the energy method and incorporating the pre-existing or formation cracks into the calculation procedure. The reasonableness of the proposed method of this study was verified by comparing the calculation results with those of OptumG2 (academic version) and existing theoretical methods. Finally, a detailed parametric study was carried out to investigate the effect of main parameters on antislip stability under unsaturated steady seepage conditions.
作者机构：
[He, Qi; Li, Ming; Yang, Yifan; Liao, Chongjie] Univ South China, Sch Civil Engn, Hengyang 421001, Peoples R China.
通讯机构：
[He, Q ] U;Univ South China, Sch Civil Engn, Hengyang 421001, Peoples R China.
关键词：
lead and zinc tailings;geopolymer foam concrete;pore structure;compressive strength;thermal conductivity;microstructure
摘要：
Geopolymer foam concrete (GFC) is a green, lightweight material produced by introducing bubbles into the geopolymer slurry. The raw materials for GFC are primarily silicon-aluminum-rich minerals or solid waste. Lead-zinc tailings (LZTs), as an industrial solid waste with high silicon-aluminum content, hold significant potential as raw materials for building materials. This study innovatively utilized LZTs to prepare GFC, incorporating MK, GGBS, and alkali activators as silicon-aluminum-rich supplementary materials and using H2O2 as a foaming agent, successfully producing GFC with excellent properties. The effects of different LZT content on the pore structure and various macroscopic properties of GFC were comprehensively evaluated. The results indicate that an appropriate addition of LZT effectively optimizes the pore structure, resulting in uniform pore distribution and pore shapes that are more spherical. Spherical pores exhibit better geometric compactness. The optimal LZT content was determined to be 40%, at which the GFC exhibits the best compressive strength, thermal conductivity, and water resistance. At this content, the dry density of GFC is 641.95 kg/m3, the compressive strength reaches 6.50 MPa after 28 days, and the thermal conductivity is 0.176 (W/(m<middle dot>K)). XRD and SEM analyses indicate that under the combined effects of geopolymerization and hydration reactions, N-A-S-H gel and C-S-H gel were formed. The preparation of GFC using LZTs shows significant potential and research value. This study also provides a feasible scheme for the recycling and utilization of LZTs.
期刊：
Mechanics of Solids,2025年60(3):2085-2099 ISSN：0025-6544
通讯作者：
Yan, XJ;Xu, Feng;Guo, CQ
作者机构：
[Yan, Xuejin; Yan, XJ] Univ South China, Sch Civil Engn, Hengyang 421001, Hunan, Peoples R China.;[Xu, Feng; Xu, F; Guo, Changqing] Univ South China, Sch Math & Phys, Hengyang 421001, Hunan, Peoples R China.
通讯机构：
[Yan, XJ ; Xu, F; Guo, CQ ] U;Univ South China, Sch Civil Engn, Hengyang 421001, Hunan, Peoples R China.;Univ South China, Sch Math & Phys, Hengyang 421001, Hunan, Peoples R China.
关键词：
fluid-conveying pipe;base excitation;impact vibration response;Pasternak base
摘要：
When the fluid-conveying pipe is buried on the surface of the base, it will not only suffer from rigid impact damage caused by base excitation and surrounding gravel, but also be affected by the characteristics of the base, which makes safety accidents extremely likely to occur during the operation of the fluid-conveying pipe. Based on the Hamilton principle, a mathematical model of simply supported fluid-conveying pipe structures with a rigid constraint on the Pasternak base under base excitation is established. The Galerkin method is used to discretize the equation of motion, and the NDFS algorithm is employed to solve the system of equations. The influence is discussed in terms of the base excitation frequency, internal flow rate, and the viscoelastic coefficient of the pipe on the model. Bifurcation diagrams, phase diagrams, Poincaré maps, and time-history curves under various parameters are used to analyze the impact vibration response of the fluid-conveying pipe system. The research shows that: grazing impact usually occurs when the system’s motion state changes under impact vibration, and at a lower base excitation frequency, grazing impact will induce incomplete chatter-impact vibration in the system; there is a particular dynamic law in the evolution between quasi-periodic motion and single-period non-impact vibration on the Poincaré map; the increase in the equivalent linear spring stiffness K and shear stiffness KG of the Pasternak base is beneficial for resisting the unstable factors caused by base excitation. The findings of this study provide theoretical support for the optimal design, operation maintenance, and safety assurance of fluid-conveying pipes on the Pasternak base.
摘要：
In practical engineering, the unilateral gap constraint impact vibration in fluid-conveying pipes is a critical concern, often arising from constraint loosening or the presence of barriers around the pipe. These factors can significantly affect the service life and safety reliability of the pipes. A tension and compression anisotropy spring with rapidly increasing restoring force in compression but almost zero restoring force in tension is proposed to simulate the unilateral gap constraint, model a fluid-conveying pipe with a Pfluger column. Its reliability is also verified based on the bifurcation phase diagram comparison between the small and large stiffness conditions. Subsequently, we establish a vibration mechanics analysis model for the cantilever fluid-conveying pipe under foundation excitation to assess the effects of basic excitation frequency, fluid velocity, distributed follower force, position coordinate of unilateral gap constraint, and the viscoelastic coefficient on the impact vibration stability of the fluid-conveying pipe. Our findings reveal that when the period-doubling bifurcation sequence is interrupted by Bare-grazing bifurcation, the system directly transitions into chaotic vibration or induces a new period-doubling bifurcation sequence, followed by re-entry into chaotic vibration. These results provide valuable insights into the intricate dynamics of fluid-conveying pipes under foundation excitation, offering a deeper understanding of the impact of various parameters on the pipe's vibration.
In practical engineering, the unilateral gap constraint impact vibration in fluid-conveying pipes is a critical concern, often arising from constraint loosening or the presence of barriers around the pipe. These factors can significantly affect the service life and safety reliability of the pipes. A tension and compression anisotropy spring with rapidly increasing restoring force in compression but almost zero restoring force in tension is proposed to simulate the unilateral gap constraint, model a fluid-conveying pipe with a Pfluger column. Its reliability is also verified based on the bifurcation phase diagram comparison between the small and large stiffness conditions. Subsequently, we establish a vibration mechanics analysis model for the cantilever fluid-conveying pipe under foundation excitation to assess the effects of basic excitation frequency, fluid velocity, distributed follower force, position coordinate of unilateral gap constraint, and the viscoelastic coefficient on the impact vibration stability of the fluid-conveying pipe. Our findings reveal that when the period-doubling bifurcation sequence is interrupted by Bare-grazing bifurcation, the system directly transitions into chaotic vibration or induces a new period-doubling bifurcation sequence, followed by re-entry into chaotic vibration. These results provide valuable insights into the intricate dynamics of fluid-conveying pipes under foundation excitation, offering a deeper understanding of the impact of various parameters on the pipe's vibration.
摘要：
Seismic events and wave action can induce volumetric strain ( ε v ) accumulation in saturated sandy soils, leading to damage to the ground surface and structures. A quantifiable relationship exists between the generation of ε v in sandy soils under drained conditions and the development of pore water pressures under undrained conditions. In this study, the impact of relative density ( D r ), cyclic stress path, and stress level on the characteristics of volumetric strain ( ε v ) generation in saturated coral sands (SCS) was evaluated through drained tests employing various cyclic stress paths. The test findings demonstrate that the rate of ε v accumulation in SCS is notably affected by the cyclic stress path. The rise in peak volumetric strain ( ε vp ) in SCS, as a function of the number of cycles, conforms to the arctangent function model. The unit cyclic stress ratio (USR) was employed as an indicator of complex cyclic loading levels. It was determined that coefficient ( ε vp ) u is positively correlated with USR at a specific D r . At the same D r , coefficient C N 1 exhibits a positive correlation with USR, while coefficient C N 2 displays a negative correlation with USR, following a power-law relationship. Irrespective of cyclic loading conditions, ε vp rises with an increase in generalized shear strain amplitude ( γ ga ). A power function model was established to represent the relationship between ε vp and γ ga . The coefficient ζ 1 decreases as D r increases. Comparisons were drawn between ε vp and γ ga for Ottawa sand and SCS. The results indicate that, as D r of Ottawa sand increases from 30 % to 70 %, the coefficient ζ 1 decreases from 1.54 to 0.73, representing a reduction of approximately 53 %. In contrast, under identical conditions, the coefficient ζ 1 of SCS exhibits a less pronounced decrease, from 1.16 to 0.79, corresponding to a reduction of roughly 32 %. These observations suggest that variations in D r have a more substantial impact on generating ε vp in Ottawa sand compared to SCS.
Seismic events and wave action can induce volumetric strain ( ε v ) accumulation in saturated sandy soils, leading to damage to the ground surface and structures. A quantifiable relationship exists between the generation of ε v in sandy soils under drained conditions and the development of pore water pressures under undrained conditions. In this study, the impact of relative density ( D r ), cyclic stress path, and stress level on the characteristics of volumetric strain ( ε v ) generation in saturated coral sands (SCS) was evaluated through drained tests employing various cyclic stress paths. The test findings demonstrate that the rate of ε v accumulation in SCS is notably affected by the cyclic stress path. The rise in peak volumetric strain ( ε vp ) in SCS, as a function of the number of cycles, conforms to the arctangent function model. The unit cyclic stress ratio (USR) was employed as an indicator of complex cyclic loading levels. It was determined that coefficient ( ε vp ) u is positively correlated with USR at a specific D r . At the same D r , coefficient C N 1 exhibits a positive correlation with USR, while coefficient C N 2 displays a negative correlation with USR, following a power-law relationship. Irrespective of cyclic loading conditions, ε vp rises with an increase in generalized shear strain amplitude ( γ ga ). A power function model was established to represent the relationship between ε vp and γ ga . The coefficient ζ 1 decreases as D r increases. Comparisons were drawn between ε vp and γ ga for Ottawa sand and SCS. The results indicate that, as D r of Ottawa sand increases from 30 % to 70 %, the coefficient ζ 1 decreases from 1.54 to 0.73, representing a reduction of approximately 53 %. In contrast, under identical conditions, the coefficient ζ 1 of SCS exhibits a less pronounced decrease, from 1.16 to 0.79, corresponding to a reduction of roughly 32 %. These observations suggest that variations in D r have a more substantial impact on generating ε vp in Ottawa sand compared to SCS.
摘要：
This study conducts the numerical implementation and solver development of four sub-models based on the Eulerian method with OpenFOAM software, which have been used in prior numerical simulations of wind-induced snow drifting. Verification studies are conducted on the sub-models to assess their applicability and limitations in the field of snow protection engineering. Wind tunnel experiments conducted on a snow fence in Hokkaido serve as a benchmark for these evaluations. A comparative analysis indicates that the mixture multiphase flow model, incorporating two-way coupling between phases, adeptly reproduces snow distribution around snow fences. In contrast, scalar transport models, which consider one-way coupling, are suitable only for studying snowdrifts in the early stage of protection engineering with relatively low snow concentrations. Efforts to integrate phase coupling effects by introducing source terms into the turbulence model are found to be unsatisfactory. By employing a mixture multiphase flow model, this study explores the effects of six typical collector fences on wind-induced snow drifting in road cuttings. Comparative analyses are performed on several aspects, including the morphology of the cutting flow field, snow distribution, snow concentration, and the protective efficacy of the fences, with the aim to evaluate the effectiveness and applicability of snow fences. The results show that collector fences exhibit effective snow protection capabilities for road cuttings. The snow fence in Hokkaido, wind fence, and the snow fence in Wyoming demonstrate the highest protection efficiency among the analyzed collector fences, indicating superior snowdrift control effectiveness within the cuttings. The protective mechanism of collector fences is to decrease the snow transport rate within the saltation layer at the entrance of the protected area, leading to a notable decrease in snow concentration within the saltation layer in the cuttings. This study offers valuable insights and suggestions for snow protection engineering in road cuttings.
This study conducts the numerical implementation and solver development of four sub-models based on the Eulerian method with OpenFOAM software, which have been used in prior numerical simulations of wind-induced snow drifting. Verification studies are conducted on the sub-models to assess their applicability and limitations in the field of snow protection engineering. Wind tunnel experiments conducted on a snow fence in Hokkaido serve as a benchmark for these evaluations. A comparative analysis indicates that the mixture multiphase flow model, incorporating two-way coupling between phases, adeptly reproduces snow distribution around snow fences. In contrast, scalar transport models, which consider one-way coupling, are suitable only for studying snowdrifts in the early stage of protection engineering with relatively low snow concentrations. Efforts to integrate phase coupling effects by introducing source terms into the turbulence model are found to be unsatisfactory. By employing a mixture multiphase flow model, this study explores the effects of six typical collector fences on wind-induced snow drifting in road cuttings. Comparative analyses are performed on several aspects, including the morphology of the cutting flow field, snow distribution, snow concentration, and the protective efficacy of the fences, with the aim to evaluate the effectiveness and applicability of snow fences. The results show that collector fences exhibit effective snow protection capabilities for road cuttings. The snow fence in Hokkaido, wind fence, and the snow fence in Wyoming demonstrate the highest protection efficiency among the analyzed collector fences, indicating superior snowdrift control effectiveness within the cuttings. The protective mechanism of collector fences is to decrease the snow transport rate within the saltation layer at the entrance of the protected area, leading to a notable decrease in snow concentration within the saltation layer in the cuttings. This study offers valuable insights and suggestions for snow protection engineering in road cuttings.
摘要：
The decommissioning of nuclear facilities and nuclear accidents may release a various amount of radioactive aerosols, which could pose a serious threat to the natural environment and human health. Therefore, there is a need to develop an eco-friendly aerosol suppressant to control the radioactive aerosol. In this paper, carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), rhamnolipid and sophorajaponica glycolipid were selected as the raw material, and the aerosol suppressant was prepared by solution polymerization. The sample was characterized by FTIR, TGA, viscosity, surface tension and contact angle analysis. The results indicated that the grafted reaction was successful. Rhamnolipid and sophorajaponica glycolipid effectively reduced the surface tension of the copolymer solution to 27.7 mN/m, and the contact angle between the polymer solution and experimental dust was decreased to 27.36°. The aerosol sedimentation experiment showed that the suppressant had a significant effect on aerosol. The sedimentation efficiency of concrete aerosols was 87.7%, and the sedimentation efficiency of radioactive aerosols reached 90.8%. It provided an eco-friendly and effective method to quickly and easily control and remove high-concentration radioactive aerosol.
作者机构：
[Chen, Guohao; Wang, Zhiqiao] Univ South China, Sch Civil Engn, Hengyang 421001, Peoples R China.;[Zhang, XY; Zhang, Xiaoyang] Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.
通讯机构：
[Zhang, XY ] U;Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.
关键词：
thermal effect;locally resonant;finite element method;tunable bandgap;defect states;waveguide
摘要：
Based on the finite element method, the modulation of the bending wave bandgap and bending waveguide of locally resonant phononic crystal (PnC) plates via a thermal environment is investigated. First, the finite element model of the PnC subjected to a thermal field is introduced; then, the modulation behavior of the bending wave bandgap of the PnC under thermal flux is illustrated; finally, the tunable waveguide of the bending waveguide of the PnC supercell is proposed to be realized by setting up a local heat source. The results show that the injected heat flux causes the PnC unit cell band structure to move toward the low-frequency region while the relative bandgap width increases. The linear defect state of the PnC supercell structure is realized by introducing a local heat source, and a new band is added to the bending wave bandgap of the original supercell. The transmission loss of the bending wave is significantly higher than that of the bending wave bandgap of the supercell in the frequency interval of the linear defect of the supercell, and the frequency response vibrational modes of the supercell structure validate the feasibility of the thermally controlled bending waveguide. This method provides a flexible and efficient control strategy for the frequency tuning of the bending wave bandgap and waveguide.
期刊：
Indoor and Built Environment,2025年34(1):251 - 263 ISSN：1420-326X
通讯作者：
Xie, D
作者机构：
[Luo, Xiao; Zhou, Zheng] Hubei Branch China Tobacco Ind Co Ltd, Enshi Cigarette Factory, Enshi, Peoples R China.;[Xie, D; Zhang, Yu-gui; Xie, Dong; Yao, Meng-yu] Univ South China, Sch Civil Engn, Changsheng West Rd, Hengyang 421001, Peoples R China.;[Zhang, Yu-gui; Xie, Dong; Yao, Meng-yu] Natl & Local Joint Engn Res Ctr Airborne Pollutant, Hengyang, Peoples R China.
通讯机构：
[Xie, D ] U;Univ South China, Sch Civil Engn, Changsheng West Rd, Hengyang 421001, Peoples R China.
关键词：
Indoor environment;temperature and humidity uniformity;air distribution;energy-saving
摘要：
Air-conditioning energy consumption accounts for a significant proportion of the total energy usage in large commercial buildings. This study utilizes computational fluid dynamics (CFD) to examine the airflow distribution in a cigarette factory with a high ceiling. Numerical simulations were performed to assess the effectiveness of various air supply methods. Using FLUENT, the researchers analyzed the uniformity of airflow, temperature and humidity fields under summer conditions. The findings indicate that employing an upper supply and lower return air method can decrease air-conditioning energy consumption by 7.25%. Field measurements were carried out to validate the numerical simulations, with the measured values used as initial parameters. The average deviation between the measured and simulated temperature and humidity in critical work areas was within 2%. The comparative analysis of the simulation and measurement results confirms the reliability and effectiveness of airflow organization simulations in large commercial buildings. These results offer a scientific foundation and computational guidance for designing and implementing energy-efficient upgrades to air-conditioning systems in similar industrial facilities.
作者机构：
[Zeng, Wengao] Natl & Local Joint Engn Res Ctr Airborne Pollutant, Hengyang 421001, Peoples R China.;[Zeng, Wengao] Univ South China, Sch Civil Engn, Hengyang 421001, Peoples R China.;[Chen, Jie] Xi An Jiao Tong Univ, Sch Environm & Chem Engn, Xian 710049, Peoples R China.;[Zhang, Ziying; Ye, Xiaoyuan; Zhang, Tuo; Zeng, Wengao; Dong, Yuchen; Zhao, Yi; Zhang, Lei; Guan, Xiangjiu] Xian Jiaotong Univ XJTU, Int Res Ctr Renewable Energy IRCRE, State Key Lab Multiphase Flow Power Engn MFPE, 28 West Xianning Rd, Xian 710049, Peoples R China.
通讯机构：
[Guan, XJ ] X;Xian Jiaotong Univ XJTU, Int Res Ctr Renewable Energy IRCRE, State Key Lab Multiphase Flow Power Engn MFPE, 28 West Xianning Rd, Xian 710049, Peoples R China.
摘要：
Thermal and mechanical damage tests and uniaxial cyclic loading–unloading tests are conducted to investigate the effect of damage degree and temperature on the mechanical behaviour of sandstone under cyclic loading. The failure characteristics are analysed via acoustic emission (AE) monitoring and particle-flow code (PFC) simulations. The results indicate that the rock mass strength first increases and then decreases. The peak strain of samples increases with temperature, thus enhancing their ductility. The residual strain decreases gradually as the number of cycles increases. Additionally, the AE signal becomes more active with increasing temperature. The peak-frequency density ranges primarily between 100 and 200 kHz and shows a distinct discontinuity during cyclic loading. Shear failure predominantly occurs during the cyclic stage, whereas tensile failure is more common during the fracturing stage. The proportion of shear cracks increases with the damage degree. The simulation results show that stress reduction is typically accompanied by a rapid increase in the number of cracks. The failure process is dominated by tensile cracks, and the crack distribution angle is approximately 90°. AE events are concentrated near the sample boundary, and the frequency distribution is approximately normal as the magnitude changes. The change trend of the b-value is consistent with that of the peak strength.
Thermal and mechanical damage tests and uniaxial cyclic loading–unloading tests are conducted to investigate the effect of damage degree and temperature on the mechanical behaviour of sandstone under cyclic loading. The failure characteristics are analysed via acoustic emission (AE) monitoring and particle-flow code (PFC) simulations. The results indicate that the rock mass strength first increases and then decreases. The peak strain of samples increases with temperature, thus enhancing their ductility. The residual strain decreases gradually as the number of cycles increases. Additionally, the AE signal becomes more active with increasing temperature. The peak-frequency density ranges primarily between 100 and 200 kHz and shows a distinct discontinuity during cyclic loading. Shear failure predominantly occurs during the cyclic stage, whereas tensile failure is more common during the fracturing stage. The proportion of shear cracks increases with the damage degree. The simulation results show that stress reduction is typically accompanied by a rapid increase in the number of cracks. The failure process is dominated by tensile cracks, and the crack distribution angle is approximately 90°. AE events are concentrated near the sample boundary, and the frequency distribution is approximately normal as the magnitude changes. The change trend of the b-value is consistent with that of the peak strength.
摘要：
Stability analysis of a fluid-conveying pipe under coaction of distributed follower force and elastic supports is conducted to work out problems like fluid-conveying pipe instability induced by pipe-flow coupling vibration in the petrochemical, aerospace, deep sea and other important engineering fields. The elastic support and the differential equation of fluid-conveying pipe motion under the coaction of flowing ore-water mixture and distributed follower force are established based on the Dirac function and Bernoulli-Euler beam model. The Galerkin method is used to discretize the differential equation by taking the mode shape function of the beam as the trail function. The results show that only flutter vibration instability occurs in the system when the elasticity coefficient is smaller than a critical value, while both divergence instability and flutter vibration instability occur in the system when the elasticity coefficient is larger than the critical value. With the increase of the distributed follower force, the critical velocity of instability decreases; the critical velocity of divergence instability is independent of the mass ratio, but the critical velocity of flutter vibration instability increases with the increase of the mass ratio. The research results provide a theoretical basis for the determination of critical flow velocity and cross-sectional dimensions within the fluid-conveying pipe, as well as the treatment of constraints at both ends.
