Phuc Hong Pham, Phuc Truong Duc, Kien Trung Hoang, Ngoc-Tam Bui
This paper presents a thermal transfer model and optimization of a V-beam dimension to improve the critical frequency fC (i.e., expanding the effective working frequency range) of an electrothermal V-shaped actuator (EVA). The obtained results are based on applying the finite difference model, a method for calculating the critical frequency, as well as conditions to ensure the mechanical stability and thermal safety of EVA. The influence of beam dimensions (i.e., length L, width , and incline angle θ of the beam) on the variation of critical frequency fC is investigated and evaluated. Moreover, the particle swarm optimization (PSO) algorithm is used to figure out the optimal beam dimensions aiming to increase the critical frequency while satisfying conditions such as mechanical stability, thermal safety, and suitable displacement of EVA. With the optimal dimensions of V-beam (L = 679 µm, = 4 µm, and θ = 1.8°), the critical frequency of the V-shaped actuator can be achieved up to 136.22 Hz at a voltage of 32 V (average increment of fC is 33.1% with the driving voltage changing from 16 V to 32 V) in comparison with the nonoptimal structure (fC is only 102.34 Hz at 32 V).
{"title":"Improving Critical Frequency of the Electrothermal V-Shaped Actuator Using the Particle Swarm Optimization Algorithm","authors":"Phuc Hong Pham, Phuc Truong Duc, Kien Trung Hoang, Ngoc-Tam Bui","doi":"10.1155/2023/2698650","DOIUrl":"https://doi.org/10.1155/2023/2698650","url":null,"abstract":"This paper presents a thermal transfer model and optimization of a V-beam dimension to improve the critical frequency <i>f</i><sub><i>C</i></sub> (i.e., expanding the effective working frequency range) of an electrothermal V-shaped actuator (EVA). The obtained results are based on applying the finite difference model, a method for calculating the critical frequency, as well as conditions to ensure the mechanical stability and thermal safety of EVA. The influence of beam dimensions (i.e., length <i>L</i>, width <span><svg height=\"6.1673pt\" style=\"vertical-align:-0.2063904pt\" version=\"1.1\" viewbox=\"-0.0498162 -5.96091 9.39034 6.1673\" width=\"9.39034pt\" xmlns=\"http://www.w3.org/2000/svg\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"><g transform=\"matrix(.013,0,0,-0.013,0,0)\"></path></g></svg>,</span> and incline angle <i>θ</i> of the beam) on the variation of critical frequency <i>f</i><sub><i>C</i></sub> is investigated and evaluated. Moreover, the particle swarm optimization (PSO) algorithm is used to figure out the optimal beam dimensions aiming to increase the critical frequency while satisfying conditions such as mechanical stability, thermal safety, and suitable displacement of EVA. With the optimal dimensions of V-beam (<i>L</i> = 679 <i>µ</i>m, <svg height=\"6.1673pt\" style=\"vertical-align:-0.2063904pt\" version=\"1.1\" viewbox=\"-0.0498162 -5.96091 9.39034 6.1673\" width=\"9.39034pt\" xmlns=\"http://www.w3.org/2000/svg\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"><g transform=\"matrix(.013,0,0,-0.013,0,0)\"><use xlink:href=\"#g113-120\"></use></g></svg> = 4 <i>µ</i>m, and <i>θ</i> = 1.8°), the critical frequency of the V-shaped actuator can be achieved up to 136.22 Hz at a voltage of 32 V (average increment of <i>f</i><sub><i>C</i></sub> is 33.1% with the driving voltage changing from 16 V to 32 V) in comparison with the nonoptimal structure (<i>f</i><sub><i>C</i></sub> is only 102.34 Hz at 32 V).","PeriodicalId":21915,"journal":{"name":"Shock and Vibration","volume":"5 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138542930","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Blasting vibration generated from blasting excavation of subway tunnel may endanger the adjacent structures buried in strata. To guarantee their safety and stability, it is crucial to understand the spatial variation law of blasting vibration in strata. In this paper, the blasting excavation of the large cross-sectional tunnel of Wuhan Metro Line 8 is studied. Three-dimensional finite element simulation is performed using the dynamic finite element program LS-DYNA, and its validity is verified by the field monitoring data. The spatial variation law of blasting vibration in layered strata is investigated through analyzed the distribution characteristic of blasting vibration in three directions, including the direction along the axis of the large cross-sectional tunnel, the direction perpendicular to the axis of the large cross-sectional tunnel, and the direction along the depth. A prediction model for blasting vibration velocity, which considers the impact of elevation differences, is established through dimensional analysis, enabling the prediction of blasting-induced vibrations at various depths in the layered strata.
{"title":"Spatial Variation Law of Blasting Vibration in Layered Strata under Blasting Excavation of Subway Tunnel","authors":"Zhen Zhang, Chuanbo Zhou, Nan Jiang, Yingkang Yao","doi":"10.1155/2023/8080987","DOIUrl":"https://doi.org/10.1155/2023/8080987","url":null,"abstract":"Blasting vibration generated from blasting excavation of subway tunnel may endanger the adjacent structures buried in strata. To guarantee their safety and stability, it is crucial to understand the spatial variation law of blasting vibration in strata. In this paper, the blasting excavation of the large cross-sectional tunnel of Wuhan Metro Line 8 is studied. Three-dimensional finite element simulation is performed using the dynamic finite element program LS-DYNA, and its validity is verified by the field monitoring data. The spatial variation law of blasting vibration in layered strata is investigated through analyzed the distribution characteristic of blasting vibration in three directions, including the direction along the axis of the large cross-sectional tunnel, the direction perpendicular to the axis of the large cross-sectional tunnel, and the direction along the depth. A prediction model for blasting vibration velocity, which considers the impact of elevation differences, is established through dimensional analysis, enabling the prediction of blasting-induced vibrations at various depths in the layered strata.","PeriodicalId":21915,"journal":{"name":"Shock and Vibration","volume":"16 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138525836","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
P. Mohanasundaram, K. Shimoyama, F. Gillot, S. Besset
Flutter-type dynamic instability induced by friction is a highly nonlinear phenomenon and computationally expensive to model through transient analysis. An efficient way to make inference of such instabilities in a dynamical system is through analyzing the first-order effect of a perturbation at one of its equilibrium with eigenvalue analysis. The contact characteristics of such dynamical systems are typically modelled through the normal compliance approach with inference from experiments. In this case, the dynamical response of the system is implied to be sensitive to the contact stiffness modelled through the normal compliance approach. Typically, with the normal compliance approach, the continuum of the contact interface is approximated through a set of nonlinear springs which can be interpreted as a collocation method. Such approximations or the numerical implication of contact formulations in general for such problems is not largely studied. We focus on a variational formulation-based contact formulation without domain decomposition which is computationally efficient with small sacrifice in accuracy, where we imply that the dynamical response can be robustly modelled with the given accuracy. Further, we expose the inadequacy of the collocation method for such problems, where the dynamical system is observed to be sensitive to the extent of inaccuracy as a result of collocation for low values of contact stiffness. The inferences numerically imply the characteristics of the dynamical system for variation in contact stiffness.
{"title":"Modelling Friction-Induced Dynamic Instability Dedicated for Isogeometric Formulation","authors":"P. Mohanasundaram, K. Shimoyama, F. Gillot, S. Besset","doi":"10.1155/2023/8669237","DOIUrl":"https://doi.org/10.1155/2023/8669237","url":null,"abstract":"Flutter-type dynamic instability induced by friction is a highly nonlinear phenomenon and computationally expensive to model through transient analysis. An efficient way to make inference of such instabilities in a dynamical system is through analyzing the first-order effect of a perturbation at one of its equilibrium with eigenvalue analysis. The contact characteristics of such dynamical systems are typically modelled through the normal compliance approach with inference from experiments. In this case, the dynamical response of the system is implied to be sensitive to the contact stiffness modelled through the normal compliance approach. Typically, with the normal compliance approach, the continuum of the contact interface is approximated through a set of nonlinear springs which can be interpreted as a collocation method. Such approximations or the numerical implication of contact formulations in general for such problems is not largely studied. We focus on a variational formulation-based contact formulation without domain decomposition which is computationally efficient with small sacrifice in accuracy, where we imply that the dynamical response can be robustly modelled with the given accuracy. Further, we expose the inadequacy of the collocation method for such problems, where the dynamical system is observed to be sensitive to the extent of inaccuracy as a result of collocation for low values of contact stiffness. The inferences numerically imply the characteristics of the dynamical system for variation in contact stiffness.","PeriodicalId":21915,"journal":{"name":"Shock and Vibration","volume":"14 3","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138525843","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ma Xingen, Pan Jun, Zou Qinghai, Li Yongyuan, Feng Fan, Wang Huifeng, Ye Xiangping, Gong Yongchun, Mou Biao
Xinzhuang Coal Mine is a typical kilometer-deep rockburst mine in the Ningzheng mining area of China Huaneng Group, which is still in the capital construction period. At present, there are a few studies on the rockburst mechanism and prevention of this mine. In order to explore the occurrence mechanism and main influencing factors of rockburst under the complex geological conditions of large buried depth, thick topsoil, and hard overburden in Xinzhuang Coal Mine, this paper, based on the analysis of the basic geological data of the mine, deeply explores the comprehensive disaster factors of Xinzhuang Coal Mine; then, uses the analytic hierarchy process to carry out quantitative analysis of each disaster factor, and finally, it obtains the impact type and occurrence mechanism of the mine. Through research, it is found that the main disaster factors of Xinzhuang Coal Mine are mining depth, coal seam thickness, coal seam thickness change, tectonic stress field, hard overburden, roadway layout, bottom coal reservation, and tunneling activities. The key to the process of the rockburst disaster in Xinzhuang Coal Mine is the superimposed effect of static and dynamic loads on the roadway surrounding the rock system. The potential rockburst type during excavation and mining is the “high static and dynamic load disturbance” type.
{"title":"Study on Mechanism and Main Influencing Factors of Rockburst under Complex Conditions of Hard and Deep Overburden","authors":"Ma Xingen, Pan Jun, Zou Qinghai, Li Yongyuan, Feng Fan, Wang Huifeng, Ye Xiangping, Gong Yongchun, Mou Biao","doi":"10.1155/2023/5582345","DOIUrl":"https://doi.org/10.1155/2023/5582345","url":null,"abstract":"Xinzhuang Coal Mine is a typical kilometer-deep rockburst mine in the Ningzheng mining area of China Huaneng Group, which is still in the capital construction period. At present, there are a few studies on the rockburst mechanism and prevention of this mine. In order to explore the occurrence mechanism and main influencing factors of rockburst under the complex geological conditions of large buried depth, thick topsoil, and hard overburden in Xinzhuang Coal Mine, this paper, based on the analysis of the basic geological data of the mine, deeply explores the comprehensive disaster factors of Xinzhuang Coal Mine; then, uses the analytic hierarchy process to carry out quantitative analysis of each disaster factor, and finally, it obtains the impact type and occurrence mechanism of the mine. Through research, it is found that the main disaster factors of Xinzhuang Coal Mine are mining depth, coal seam thickness, coal seam thickness change, tectonic stress field, hard overburden, roadway layout, bottom coal reservation, and tunneling activities. The key to the process of the rockburst disaster in Xinzhuang Coal Mine is the superimposed effect of static and dynamic loads on the roadway surrounding the rock system. The potential rockburst type during excavation and mining is the “high static and dynamic load disturbance” type.","PeriodicalId":21915,"journal":{"name":"Shock and Vibration","volume":"50 9","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136281647","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
To alleviate the problem of unsatisfactory target strength and scattering stability of an underwater corner reflector, a method to enhance the acoustic scattering characteristics using a vacuum cavity as an acoustic reflecting layer is proposed. According to the principle of acoustic impedance mismatch of a water-reflecting layer, a vacuum cavity corner reflector is designed to take advantage of the property that sound waves cannot propagate under vacuum conditions. The acoustic vacuum reflecting layer has a theoretical acoustic reflecting coefficient of one. Comparative analyses are carried out with the single-layer metal corner reflector in terms of frequency and angle of incidence. For the concave structure of the underwater corner reflector, the structural finite element software ANSYS combined with the acoustic analysis software SYSNOISE is used to simulate and analyse the acoustic scattering characteristics, and the consistency of the simulation calculations and experimental data is verified through the pool experiments for typical cases. The results show that under the same reflection area, the vacuum cavity underwater corner reflector has large scattering intensity, good antiacoustic performance, no obvious frequency characteristics, and good decoupling effects. The target echo intensity value can be increased by 2 dB for better scattering stability. The overall weight is reduced by about 20 kg, with considerable engineering practicality, proving that the true cavity corner reflector is an ideal underwater acoustic counter-acoustic device.
{"title":"A Method for Enhancing the Acoustic Scattering Characteristics of Underwater Acoustic Corner Reflectors in Vacuum Cavities","authors":"Jingzhuo Zhang, Dawei Xiao, Taotao Xie","doi":"10.1155/2023/4508247","DOIUrl":"https://doi.org/10.1155/2023/4508247","url":null,"abstract":"To alleviate the problem of unsatisfactory target strength and scattering stability of an underwater corner reflector, a method to enhance the acoustic scattering characteristics using a vacuum cavity as an acoustic reflecting layer is proposed. According to the principle of acoustic impedance mismatch of a water-reflecting layer, a vacuum cavity corner reflector is designed to take advantage of the property that sound waves cannot propagate under vacuum conditions. The acoustic vacuum reflecting layer has a theoretical acoustic reflecting coefficient of one. Comparative analyses are carried out with the single-layer metal corner reflector in terms of frequency and angle of incidence. For the concave structure of the underwater corner reflector, the structural finite element software ANSYS combined with the acoustic analysis software SYSNOISE is used to simulate and analyse the acoustic scattering characteristics, and the consistency of the simulation calculations and experimental data is verified through the pool experiments for typical cases. The results show that under the same reflection area, the vacuum cavity underwater corner reflector has large scattering intensity, good antiacoustic performance, no obvious frequency characteristics, and good decoupling effects. The target echo intensity value can be increased by 2 dB for better scattering stability. The overall weight is reduced by about 20 kg, with considerable engineering practicality, proving that the true cavity corner reflector is an ideal underwater acoustic counter-acoustic device.","PeriodicalId":21915,"journal":{"name":"Shock and Vibration","volume":"3 5","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135584779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The elastic material properties which change momentarily and locally under the high deformation rate due to the movement of a wavefront are presented. The work contains mathematical formulation, semianalytical results, numerical formulations, and simulation results demonstrating the effectiveness of modifying the rheological properties of the elastic material upon shock load or contact with a rigid obstacle. While the semianalytical solutions can be obtained in a narrow time interval, numerical solutions allow us to track the process of wavefront reflections from edges. The effectiveness of reducing the physical quantities significant for impact in the presented examples reaches 30–70% of forces or accelerations, depending on the adopted criteria.
{"title":"Smart Elastic Material with a Moving Local Stiffness Zone for Reducing the Effects of Impact Loading","authors":"Dai Zhao, Bartłomiej Dyniewicz, Czesław I. Bajer","doi":"10.1155/2023/6698248","DOIUrl":"https://doi.org/10.1155/2023/6698248","url":null,"abstract":"The elastic material properties which change momentarily and locally under the high deformation rate due to the movement of a wavefront are presented. The work contains mathematical formulation, semianalytical results, numerical formulations, and simulation results demonstrating the effectiveness of modifying the rheological properties of the elastic material upon shock load or contact with a rigid obstacle. While the semianalytical solutions can be obtained in a narrow time interval, numerical solutions allow us to track the process of wavefront reflections from edges. The effectiveness of reducing the physical quantities significant for impact in the presented examples reaches 30–70% of forces or accelerations, depending on the adopted criteria.","PeriodicalId":21915,"journal":{"name":"Shock and Vibration","volume":"41 19","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135774464","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mohammad Hossein Razmkhah, Mohsen Ghaderi, Mohsen Gerami
The test results on hourglass specimens of steel under repetitive sine loads provide graphs that indicate the stress range in terms of the number of cycles to failure and are known as S-N curves. Using this curve, it is determined that if the applied stress is less than a certain level, failure will not occur as the number of load cycles increases. The S-N curve can be affected by several factors such as yield stress, temperature, surface properties, and corrosion. In this research, the S-N curve has been investigated for two types of high-strength steels, S690 and S460, as well as two types of mild-strength steels, S235 and S355, at 25°C, and S355 with corrosion. The numbers of samples used for S235 and S460 steels were 45 each while S355 and S690 steels were 36 each and for S355 with corrosion was 15 with the high cycle fatigue curve obtained for them. To investigate the effect of plate thickness on the high cycle fatigue of the samples, four sets of 24-piece S235 steel samples, being 96 samples in total, were made of plates with different thicknesses of 8, 12, 15, and 20 mm and tested. Finally, a four-story three-span steel moment frame was designed, and under the Northridge earthquake record, the high cycle fatigue was investigated. It was observed that the high cycle fatigue was not effective for the mentioned structure under the Northridge earthquake record, but in the corroded structure, damage from high cycle fatigue occurs under this record.
{"title":"Experimental Study on Seismic Fatigue Capacity of High- and Mild-Strength Structural Steels with and without Corrosion","authors":"Mohammad Hossein Razmkhah, Mohsen Ghaderi, Mohsen Gerami","doi":"10.1155/2023/9107240","DOIUrl":"https://doi.org/10.1155/2023/9107240","url":null,"abstract":"The test results on hourglass specimens of steel under repetitive sine loads provide graphs that indicate the stress range in terms of the number of cycles to failure and are known as S-N curves. Using this curve, it is determined that if the applied stress is less than a certain level, failure will not occur as the number of load cycles increases. The S-N curve can be affected by several factors such as yield stress, temperature, surface properties, and corrosion. In this research, the S-N curve has been investigated for two types of high-strength steels, S690 and S460, as well as two types of mild-strength steels, S235 and S355, at 25°C, and S355 with corrosion. The numbers of samples used for S235 and S460 steels were 45 each while S355 and S690 steels were 36 each and for S355 with corrosion was 15 with the high cycle fatigue curve obtained for them. To investigate the effect of plate thickness on the high cycle fatigue of the samples, four sets of 24-piece S235 steel samples, being 96 samples in total, were made of plates with different thicknesses of 8, 12, 15, and 20 mm and tested. Finally, a four-story three-span steel moment frame was designed, and under the Northridge earthquake record, the high cycle fatigue was investigated. It was observed that the high cycle fatigue was not effective for the mentioned structure under the Northridge earthquake record, but in the corroded structure, damage from high cycle fatigue occurs under this record.","PeriodicalId":21915,"journal":{"name":"Shock and Vibration","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135773306","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Juan Du, Xiao-Peng Lei, Di-Fan Ren, Zai-Cheng Wang, Yang Zhang
This study aimed to examine the aseismic performance of the pile-raft systems with various connection forms. The related shaking table test and numerical simulation were performed for in-depth investigation. The acceleration response spectra on the top of the soil layer and raft were obtained and plotted for contrastive analysis based on the model test at a reduced scale of 1 : 30 and finite element numerical simulation. Accordingly, the working mechanisms of the pile-raft systems in conventional connections with the embedment of the compressible blocks and cushion layers under cyclic loading were explored. The results showed that the embedment of the cushion layer on the pile top could most significantly mobilize the potential of the foundation soil, effectively reduce the bending moment peak of the pile, and reduce the acceleration amplification effect on the top of the soil layer and raft. The embedment of the compressible block on the pile top most markedly reduced the bending moment peak of the pile and effectively mobilized the potential of the foundation soil, which was most favorable for lowering the amplification effect of acceleration on the top of the soil layer and raft.
{"title":"Dynamic Response of Pile-Raft Systems with Various Forms of Connection under Cyclic Condition","authors":"Juan Du, Xiao-Peng Lei, Di-Fan Ren, Zai-Cheng Wang, Yang Zhang","doi":"10.1155/2023/3775654","DOIUrl":"https://doi.org/10.1155/2023/3775654","url":null,"abstract":"This study aimed to examine the aseismic performance of the pile-raft systems with various connection forms. The related shaking table test and numerical simulation were performed for in-depth investigation. The acceleration response spectra on the top of the soil layer and raft were obtained and plotted for contrastive analysis based on the model test at a reduced scale of 1 : 30 and finite element numerical simulation. Accordingly, the working mechanisms of the pile-raft systems in conventional connections with the embedment of the compressible blocks and cushion layers under cyclic loading were explored. The results showed that the embedment of the cushion layer on the pile top could most significantly mobilize the potential of the foundation soil, effectively reduce the bending moment peak of the pile, and reduce the acceleration amplification effect on the top of the soil layer and raft. The embedment of the compressible block on the pile top most markedly reduced the bending moment peak of the pile and effectively mobilized the potential of the foundation soil, which was most favorable for lowering the amplification effect of acceleration on the top of the soil layer and raft.","PeriodicalId":21915,"journal":{"name":"Shock and Vibration","volume":"112 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135818391","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The aim of this study is to investigate damage processes and fracture mechanisms in the rock surrounding a roadway under blasting-induced disturbance in a high-stress environment. A disturbance test involving blasting of the rock surrounding a roadway under different lateral pressure coefficients was conducted using high-precision acoustic emission (AE) monitoring. Based thereon, the spatiotemporal evolution and cluster characteristics of microcracks in the surrounding rock of the roadway under dynamic disturbance induced by explosive blasting were obtained, and stress transfer, adjustment, and redistribution in the rock mass were revealed. Moreover, a method for describing the progressive damage to the rock mass was established. The conclusions were as follows: the high-stress environment was conducive to microcrack initiation and propagation in the specimens, and the failure patterns of the surrounding rock of the roadway under different lateral pressure coefficients differed. The direction of crack propagation in the rock surrounding the roadway is opposite to that of the maximum principal stress applied to the rock mass. Blasting-induced disturbance intensifies crack initiation and accelerates damage accumulation and macrofracture formation in the rock mass. The macroscopic failure zone in a model is correlated with the ultimate distribution of apparent stress, and the apparent stress can reflect the adjustment of the stress field therein. The damage variable, characterized by the ratio of the number of AE events, can reveal the evolution of damage in the rock surrounding a roadway.
{"title":"Damage Process and Fracture Mechanisms in the Rock Surrounding a Roadway Caused by Blasting-Induced Disturbance under High Stress","authors":"Gang Lei, Dawei Wu, Xiaozhang Shi","doi":"10.1155/2023/3548281","DOIUrl":"https://doi.org/10.1155/2023/3548281","url":null,"abstract":"The aim of this study is to investigate damage processes and fracture mechanisms in the rock surrounding a roadway under blasting-induced disturbance in a high-stress environment. A disturbance test involving blasting of the rock surrounding a roadway under different lateral pressure coefficients was conducted using high-precision acoustic emission (AE) monitoring. Based thereon, the spatiotemporal evolution and cluster characteristics of microcracks in the surrounding rock of the roadway under dynamic disturbance induced by explosive blasting were obtained, and stress transfer, adjustment, and redistribution in the rock mass were revealed. Moreover, a method for describing the progressive damage to the rock mass was established. The conclusions were as follows: the high-stress environment was conducive to microcrack initiation and propagation in the specimens, and the failure patterns of the surrounding rock of the roadway under different lateral pressure coefficients differed. The direction of crack propagation in the rock surrounding the roadway is opposite to that of the maximum principal stress applied to the rock mass. Blasting-induced disturbance intensifies crack initiation and accelerates damage accumulation and macrofracture formation in the rock mass. The macroscopic failure zone in a model is correlated with the ultimate distribution of apparent stress, and the apparent stress can reflect the adjustment of the stress field therein. The damage variable, characterized by the ratio of the number of AE events, can reveal the evolution of damage in the rock surrounding a roadway.","PeriodicalId":21915,"journal":{"name":"Shock and Vibration","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135222501","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Large temperature differences exist between the winter and summer seasons in different regions of China. Such temperature differences, caused by seasonal changes, may affect the life cycles of piles. Under natural conditions, such as long-term operation under the ambient environment and loads, piles and the surrounding soil undergo peel damage. To study such peel damage between the pile and soil at different temperatures, we installed concrete test piles in soil and subjected them to different temperatures. A crack with a width of 2 cm, depth of 10 cm, and damage range of 90° was applied at the side of the piles. Furthermore, a horizontal impact load was applied near the top of the pile and a piezoelectric ceramic sensor was used to obtain the stress wave response signals. The experimental results reveal that with a decrease in the soil temperature, the amplitude and fluctuation range of the signals received by the piezoelectric sensor decreased. According to the experimental results, in the group with the greatest influence of temperature, keeping other conditions unchanged and setting different crack depths, the horizontal impact load can also be introduced to observe the frequency change. It can be observed that the larger the crack depth, the smaller the frequency. Finally, ABAQUS was used for simulations, whose results were found to be consistent with those of the experiments. This paper describes a method for determining the safety of soil and piles with peel damage at different temperatures, and it also provides a validation of the necessity of holding the rest constant.
{"title":"Monitoring Soil-Pile Stripping Damage at Different Temperatures via Piezoelectric Ceramic Sensors","authors":"Daopei Zhu, Xu Liu, Zhangli Wang, Xiaoli Cai","doi":"10.1155/2023/4051413","DOIUrl":"https://doi.org/10.1155/2023/4051413","url":null,"abstract":"Large temperature differences exist between the winter and summer seasons in different regions of China. Such temperature differences, caused by seasonal changes, may affect the life cycles of piles. Under natural conditions, such as long-term operation under the ambient environment and loads, piles and the surrounding soil undergo peel damage. To study such peel damage between the pile and soil at different temperatures, we installed concrete test piles in soil and subjected them to different temperatures. A crack with a width of 2 cm, depth of 10 cm, and damage range of 90° was applied at the side of the piles. Furthermore, a horizontal impact load was applied near the top of the pile and a piezoelectric ceramic sensor was used to obtain the stress wave response signals. The experimental results reveal that with a decrease in the soil temperature, the amplitude and fluctuation range of the signals received by the piezoelectric sensor decreased. According to the experimental results, in the group with the greatest influence of temperature, keeping other conditions unchanged and setting different crack depths, the horizontal impact load can also be introduced to observe the frequency change. It can be observed that the larger the crack depth, the smaller the frequency. Finally, ABAQUS was used for simulations, whose results were found to be consistent with those of the experiments. This paper describes a method for determining the safety of soil and piles with peel damage at different temperatures, and it also provides a validation of the necessity of holding the rest constant.","PeriodicalId":21915,"journal":{"name":"Shock and Vibration","volume":"33 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136104097","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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