Pub Date : 2023-09-28DOI: 10.13052/ejcm2642-2085.3234
Li Peijun, Lu Hao, Li Qing
As the construction of mountainous highways continues to heat up, the stability analysis of road graben slopes becomes one of the current research hotspots. In this paper, based on the saturated-unsaturated seepage theory, the force analysis of the road graben slope under rainfall conditions and its laws are studied. Firstly, the damage mode of the road graben slope and its three damage stages of creeping deformation, sliding damage and tendency to stability are summarized according to the engineering practice and literature survey, and the right side of the road graben slope from K316+439 to K316+859 of Longlian Expressway is monitored, so as to amend the next theoretical analysis. The three stages of rainfall infiltration were analyzed, the state variables and material variables of soil water were selected according to the continuous medium theory and the soil water suction analysis was carried out. Based on the saturated-unsaturated seepage theory, the fluid-structure interaction mathematical model and soil moisture characteristic curve (SWCC) model under rainfall infiltration conditions were established, and the stress of the cutting slope under saturation conditions was analyzed. The experimental results show that for the soil at the foot of the slope, the infiltration depth of rainfall is limited due to the low permeability coefficient, and the change of seepage field is not obvious; the longer the rainfall is held, the deeper the infiltration depth is, and the rainfall will continuously replenish the groundwater, so the force on the slope of the road graben will increase continuously and finally reach the limit of damage. When the rainfall intensity is 5mm-h-1, the decline of stability coefficient for 48 h is 0.121; the initial stability coefficient of the slope is the largest when the dip angle of the weak interlayer is equal to 25∘, and the stability coefficient decreases rapidly with the rainfall time, and when the rainfall reaches 60 h, the stability coefficient tends to be stable and the equilibrium of the slope force no longer changes.
{"title":"Mechanical Analysis of Road Graben Slopes Based on Saturated-Unsaturated Seepage Theory","authors":"Li Peijun, Lu Hao, Li Qing","doi":"10.13052/ejcm2642-2085.3234","DOIUrl":"https://doi.org/10.13052/ejcm2642-2085.3234","url":null,"abstract":"As the construction of mountainous highways continues to heat up, the stability analysis of road graben slopes becomes one of the current research hotspots. In this paper, based on the saturated-unsaturated seepage theory, the force analysis of the road graben slope under rainfall conditions and its laws are studied. Firstly, the damage mode of the road graben slope and its three damage stages of creeping deformation, sliding damage and tendency to stability are summarized according to the engineering practice and literature survey, and the right side of the road graben slope from K316+439 to K316+859 of Longlian Expressway is monitored, so as to amend the next theoretical analysis. The three stages of rainfall infiltration were analyzed, the state variables and material variables of soil water were selected according to the continuous medium theory and the soil water suction analysis was carried out. Based on the saturated-unsaturated seepage theory, the fluid-structure interaction mathematical model and soil moisture characteristic curve (SWCC) model under rainfall infiltration conditions were established, and the stress of the cutting slope under saturation conditions was analyzed. The experimental results show that for the soil at the foot of the slope, the infiltration depth of rainfall is limited due to the low permeability coefficient, and the change of seepage field is not obvious; the longer the rainfall is held, the deeper the infiltration depth is, and the rainfall will continuously replenish the groundwater, so the force on the slope of the road graben will increase continuously and finally reach the limit of damage. When the rainfall intensity is 5mm-h-1, the decline of stability coefficient for 48 h is 0.121; the initial stability coefficient of the slope is the largest when the dip angle of the weak interlayer is equal to 25∘, and the stability coefficient decreases rapidly with the rainfall time, and when the rainfall reaches 60 h, the stability coefficient tends to be stable and the equilibrium of the slope force no longer changes.","PeriodicalId":45463,"journal":{"name":"European Journal of Computational Mechanics","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135344671","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-11DOI: 10.13052/ejcm2642-2085.3222
Yin Zhenyu
With the rapid development in the field of road traffic, the problems of slip cracking and U-shaped cracks on the surface of asphalt pavement are becoming more and more prominent, which seriously affect the safety and service life of roads. In order to solve this problem, a reliable asphalt pavement model is established in this study by combining the joint simulation and secondary development of experimental test parameters. The model can accurately simulate the slip cracking of asphalt pavements under different conditions and provide detailed parametric analysis of the factors affecting crack development. The results show that the inter-ply bond damage no longer deteriorates when the inter-ply strength is 0.3 MPa, indicating that the form of inter-ply contact plays a role in controlling the development of slip cracks. In addition, the maximum interlayer shear stress increased by 21.1% during the increase of vehicle axle load from 100 kN to 200 kN on the asphalt pavement, which led to an increase in the length of slip cracks. Meanwhile, the maximum longitudinal tensile stress in the asphalt pavement surface layer increased by 10.2% and the maximum shear stress increased by 18.3% when the elastic modulus of the asphalt pavement surface layer was increased from 7500 MPa to 14500 MPa.
{"title":"Mechanical Characteristics and Correlation Analysis of Crack Propagation and Slip Cracking in Asphalt Pavement Surface Layer","authors":"Yin Zhenyu","doi":"10.13052/ejcm2642-2085.3222","DOIUrl":"https://doi.org/10.13052/ejcm2642-2085.3222","url":null,"abstract":"With the rapid development in the field of road traffic, the problems of slip cracking and U-shaped cracks on the surface of asphalt pavement are becoming more and more prominent, which seriously affect the safety and service life of roads. In order to solve this problem, a reliable asphalt pavement model is established in this study by combining the joint simulation and secondary development of experimental test parameters. The model can accurately simulate the slip cracking of asphalt pavements under different conditions and provide detailed parametric analysis of the factors affecting crack development. The results show that the inter-ply bond damage no longer deteriorates when the inter-ply strength is 0.3 MPa, indicating that the form of inter-ply contact plays a role in controlling the development of slip cracks. In addition, the maximum interlayer shear stress increased by 21.1% during the increase of vehicle axle load from 100 kN to 200 kN on the asphalt pavement, which led to an increase in the length of slip cracks. Meanwhile, the maximum longitudinal tensile stress in the asphalt pavement surface layer increased by 10.2% and the maximum shear stress increased by 18.3% when the elastic modulus of the asphalt pavement surface layer was increased from 7500 MPa to 14500 MPa.","PeriodicalId":45463,"journal":{"name":"European Journal of Computational Mechanics","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48630479","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-11DOI: 10.13052/ejcm2642-2085.3223
R. Selvamani, S. Mahesh, F. Ebrahimi
In this study, the effect of nonlocal scale value and two phases lags on the free vibration of generalized magneto thermoelastic multilayered LEMV (Linear Elastic Material with Voids)/CFRP (Carbon Fiber Reinforced Polymer) composite cylinder is studied using nonlocal form of linear theory of elasticity. The governing equation of motion is established in longitudinal axis and variable separation model is used to transform the governing equations into a system of differential equations. To investigate vibration analysis from frequency equations, the stress free boundary conditions are adopted at the inner, outer and interface boundaries. The graphical representation of the numerically calculated results for frequency shift, natural frequency, and thermoelastic damping is presented. A special care has been taken to inspect the effect of nonlocal parameter on the aforementioned quantities. The results suggest that the nonlocal scale and the phase lag parameters alter the vibration characteristics of composite cylinders significantly.
{"title":"Effect of Nonlocal Elasticity and Phase Lags on the Magneto Thermoelastic Waves in a Composite Cylinder with Hall Current","authors":"R. Selvamani, S. Mahesh, F. Ebrahimi","doi":"10.13052/ejcm2642-2085.3223","DOIUrl":"https://doi.org/10.13052/ejcm2642-2085.3223","url":null,"abstract":"In this study, the effect of nonlocal scale value and two phases lags on the free vibration of generalized magneto thermoelastic multilayered LEMV (Linear Elastic Material with Voids)/CFRP (Carbon Fiber Reinforced Polymer) composite cylinder is studied using nonlocal form of linear theory of elasticity. The governing equation of motion is established in longitudinal axis and variable separation model is used to transform the governing equations into a system of differential equations. To investigate vibration analysis from frequency equations, the stress free boundary conditions are adopted at the inner, outer and interface boundaries. The graphical representation of the numerically calculated results for frequency shift, natural frequency, and thermoelastic damping is presented. A special care has been taken to inspect the effect of nonlocal parameter on the aforementioned quantities. The results suggest that the nonlocal scale and the phase lag parameters alter the vibration characteristics of composite cylinders significantly.","PeriodicalId":45463,"journal":{"name":"European Journal of Computational Mechanics","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43485051","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-11DOI: 10.13052/ejcm2642-2085.3224
Zhang Shihao, Han Lingjie, Tang Huarui
With the widespread use of deep foundation pit engineering in engineering construction, the force calculation problem about deep foundation pit support engineering has become a common problem in today’s engineering construction process. In this paper, based on the elastic foundation beam method, a simplified mechanical model of pile-anchored structure is proposed, and a systematic and practical calculation method is proposed for the force and deformation calculation of deep foundation pit support structure. The method simplifies the support structure as a vertically placed elastic foundation beam, the support, anchor and geotechnical body are replaced by a spring system, the spring stiffness of geotechnical soil can be calculated by the deformation modulus of geotechnical soil, and a systematic calculation method is proposed for the dynamic characteristics of the construction and structure of the foundation pit project; Based on the monitoring data of a deep foundation pit project, the calculation method of the simplified mechanical model proposed in this paper is verified, and the theoretical calculation value is compared with the field monitoring results; Single factor analysis is carried out on the detailed parameters of pile-anchor supporting structure to study the influence of cable prestress, cable dip Angle, pile diameter, pile length and other related parameters on the deformation and stress characteristics of supporting structure. Then the orthogonal combination of all factors is carried out to propose the optimization design. The results show that the maximum settlement deformation of the calculated value is 23.437 mm, and the maximum settlement deformation of the monitored value is 26.517 mm, and the difference between them is small. The maximum bending moment is 1210 kN⋅m after 150 kN and 250 kN horizontal prestressing is added to the second- and third-layer anchors respectively. After optimization, the maximum bending moment of pile row is 336.87 kN⋅m, and the maximum horizontal displacement of pile body is 16.505 mm, which is reduced by 11.97% compared with the original design.
{"title":"Force Calculation of Mechanical Model of Pile-anchored Support Structure Based on Elastic Foundation Beam Method","authors":"Zhang Shihao, Han Lingjie, Tang Huarui","doi":"10.13052/ejcm2642-2085.3224","DOIUrl":"https://doi.org/10.13052/ejcm2642-2085.3224","url":null,"abstract":"With the widespread use of deep foundation pit engineering in engineering construction, the force calculation problem about deep foundation pit support engineering has become a common problem in today’s engineering construction process. In this paper, based on the elastic foundation beam method, a simplified mechanical model of pile-anchored structure is proposed, and a systematic and practical calculation method is proposed for the force and deformation calculation of deep foundation pit support structure. The method simplifies the support structure as a vertically placed elastic foundation beam, the support, anchor and geotechnical body are replaced by a spring system, the spring stiffness of geotechnical soil can be calculated by the deformation modulus of geotechnical soil, and a systematic calculation method is proposed for the dynamic characteristics of the construction and structure of the foundation pit project; Based on the monitoring data of a deep foundation pit project, the calculation method of the simplified mechanical model proposed in this paper is verified, and the theoretical calculation value is compared with the field monitoring results; Single factor analysis is carried out on the detailed parameters of pile-anchor supporting structure to study the influence of cable prestress, cable dip Angle, pile diameter, pile length and other related parameters on the deformation and stress characteristics of supporting structure. Then the orthogonal combination of all factors is carried out to propose the optimization design. The results show that the maximum settlement deformation of the calculated value is 23.437 mm, and the maximum settlement deformation of the monitored value is 26.517 mm, and the difference between them is small. The maximum bending moment is 1210 kN⋅m after 150 kN and 250 kN horizontal prestressing is added to the second- and third-layer anchors respectively. After optimization, the maximum bending moment of pile row is 336.87 kN⋅m, and the maximum horizontal displacement of pile body is 16.505 mm, which is reduced by 11.97% compared with the original design.","PeriodicalId":45463,"journal":{"name":"European Journal of Computational Mechanics","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44798439","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-11DOI: 10.13052/ejcm2642-2085.3221
Guo Yunhong, Zhao Liang
The limit equilibrium strip method of slope has become mature, but because of the complexity of slope instability with many degrees of freedom and high nonlinear, a more three-dimensional and mature method is needed for slope problems. Based on the overall force balance and moment balance of slope, a unified model of three dimensional limit balance methods is established in this paper. Given different assumptions, the analytical expressions of each traditional model are obtained to avoid the problem of difficult boundary treatment when the original method is divided into bars and columns. The influence of the trailing edge point B and shear outlet A on the central axis of the sliding body, and the control arc radius variable t on the calculated value of the three-dimensional slope stability coefficient is discussed in detail. Then, based on the simulated annealing algorithm, the state generating function, state accepting function and temperature updating function are constructed, and the calculation method of optimizing the sliding surface search of the slope by using the simulated annealing algorithm is proposed, and the stability analysis of the slope of a hydropower reservoir dam area in Guangxi is carried out. The results show that the position of the sliding surface obtained by searching around the design value K = 1.10 is basically consistent with the actual one, which proves that the mechanical analysis method of coupling SA and limit equilibrium is convenient and efficient in the slope stability analysis.
{"title":"Slope Stability Analysis Based on the Coupling of SA and Limit Equilibrium Mechanics","authors":"Guo Yunhong, Zhao Liang","doi":"10.13052/ejcm2642-2085.3221","DOIUrl":"https://doi.org/10.13052/ejcm2642-2085.3221","url":null,"abstract":"The limit equilibrium strip method of slope has become mature, but because of the complexity of slope instability with many degrees of freedom and high nonlinear, a more three-dimensional and mature method is needed for slope problems. Based on the overall force balance and moment balance of slope, a unified model of three dimensional limit balance methods is established in this paper. Given different assumptions, the analytical expressions of each traditional model are obtained to avoid the problem of difficult boundary treatment when the original method is divided into bars and columns. The influence of the trailing edge point B and shear outlet A on the central axis of the sliding body, and the control arc radius variable t on the calculated value of the three-dimensional slope stability coefficient is discussed in detail. Then, based on the simulated annealing algorithm, the state generating function, state accepting function and temperature updating function are constructed, and the calculation method of optimizing the sliding surface search of the slope by using the simulated annealing algorithm is proposed, and the stability analysis of the slope of a hydropower reservoir dam area in Guangxi is carried out. The results show that the position of the sliding surface obtained by searching around the design value K = 1.10 is basically consistent with the actual one, which proves that the mechanical analysis method of coupling SA and limit equilibrium is convenient and efficient in the slope stability analysis.","PeriodicalId":45463,"journal":{"name":"European Journal of Computational Mechanics","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46180915","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-30DOI: 10.13052/ejcm2642-2085.3211
Cheng Danjiang, Hua Junfeng, Zhu Jianguo, Ji Yang, Hu Zhaoguang
The research on the calculation method of tunnel envelope pressure is a key issue in the design of tunnel engineering support structure. Based on the limit equilibrium theory, this paper proposes a method to calculate the surrounding rock pressure in shallow buried loess tunnels. Firstly, based on the investigation of the damage mode of the loess tunnel surrounding rock and the field measurement results of the surrounding rock pressure, the damage mode of the loess tunnel is proposed, and then a method of calculating the surrounding rock pressure applicable to the shallow buried loess tunnel is derived according to the limit equilibrium condition of the tunnel square soil body and the side wedge; the basic mechanical parameters are known in this method, so only the rupture angle β needs to be determined, and the rupture angle calculation model in the shallow buried loess tunnel is proposed Three assumptions are made in the rupture angle calculation model, and the rupture angle calculation formula is derived according to the stress state on the slip surface of the surrounding rock; the pressure of the surrounding rock in the loess tunnel obtained by this method is compared with four methods, namely, the pressure theory of the surrounding rock in the existing loose body of Taishaki, the pressure formula of the deeply buried surrounding rock in the railroad tunnel design code, the Beer Baumann method, and the Xie Jiayi method, in order to verify the correctness and validity of the calculation method used, and to analyze the influence of different parameters on the surrounding rock pressure. The innovation of this paper lies in the derivation of a method for calculating the pressure in the surrounding rock of a shallow buried loess tunnel using the limit equilibrium theory, and also further proposes a formula for calculating the rupture angle. The pressure of surrounding rock decreases with the increase of static earth pressure coefficient, lateral pressure coefficient, friction angle and cohesion in soil, but the static earth pressure coefficient has a greater influence on the surrounding rock pressure. With the increase of sagittal span ratio, tunnel burial depth and soil weight, the surrounding rock pressure peaked with the increase of tunnel burial depth, and the surrounding rock pressure curve increased first and then decreased.
{"title":"Calculation of Rock Pressure in Loess Tunnels Based on Limit Equilibrium Theory and Analysis of Influencing Factors","authors":"Cheng Danjiang, Hua Junfeng, Zhu Jianguo, Ji Yang, Hu Zhaoguang","doi":"10.13052/ejcm2642-2085.3211","DOIUrl":"https://doi.org/10.13052/ejcm2642-2085.3211","url":null,"abstract":"The research on the calculation method of tunnel envelope pressure is a key issue in the design of tunnel engineering support structure. Based on the limit equilibrium theory, this paper proposes a method to calculate the surrounding rock pressure in shallow buried loess tunnels. Firstly, based on the investigation of the damage mode of the loess tunnel surrounding rock and the field measurement results of the surrounding rock pressure, the damage mode of the loess tunnel is proposed, and then a method of calculating the surrounding rock pressure applicable to the shallow buried loess tunnel is derived according to the limit equilibrium condition of the tunnel square soil body and the side wedge; the basic mechanical parameters are known in this method, so only the rupture angle β needs to be determined, and the rupture angle calculation model in the shallow buried loess tunnel is proposed Three assumptions are made in the rupture angle calculation model, and the rupture angle calculation formula is derived according to the stress state on the slip surface of the surrounding rock; the pressure of the surrounding rock in the loess tunnel obtained by this method is compared with four methods, namely, the pressure theory of the surrounding rock in the existing loose body of Taishaki, the pressure formula of the deeply buried surrounding rock in the railroad tunnel design code, the Beer Baumann method, and the Xie Jiayi method, in order to verify the correctness and validity of the calculation method used, and to analyze the influence of different parameters on the surrounding rock pressure. The innovation of this paper lies in the derivation of a method for calculating the pressure in the surrounding rock of a shallow buried loess tunnel using the limit equilibrium theory, and also further proposes a formula for calculating the rupture angle. The pressure of surrounding rock decreases with the increase of static earth pressure coefficient, lateral pressure coefficient, friction angle and cohesion in soil, but the static earth pressure coefficient has a greater influence on the surrounding rock pressure. With the increase of sagittal span ratio, tunnel burial depth and soil weight, the surrounding rock pressure peaked with the increase of tunnel burial depth, and the surrounding rock pressure curve increased first and then decreased.","PeriodicalId":45463,"journal":{"name":"European Journal of Computational Mechanics","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44792881","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-30DOI: 10.13052/ejcm2642-2085.3214
Teng Xiaolei
In this paper, the design requirements of the hydraulic testing machine are based on the actual force conditions. Static and dynamic performance analyses of the stressed components of the hydraulic machine are carried out and the mechanical topology is optimized. Combining the static and dynamic objective functions of the structure, a fast variable density topology method is proposed, thus improving the optimization efficiency. After setting the positions of the optimized and non-optimized regions. It can be found that the optimized mechanical performance is more superior as the number of iterations increases. The results show that the stress in the strut is 175.75 MPa and the maximum stress in the upper beam structure is 43.708 MPa. The first sixth order frequency is much higher than the operating frequency of 3 Hz. The final results of the mechanical topology optimization analysis show. The optimized structure of the upper, middle and lower crossbeams resulted in a mass reduction of 38%, 36% and 5.57%. The maximum stresses in the upper and middle crossbeams were reduced by 10.33%, 8.3% and 51.8%, respectively. The deformation was reduced by 6.14% at the fastest time; the inherent frequency of the first 3 orders was increased to achieve light weight. The overall mechanical properties became better after optimization, and the dynamic and static stability of the frame was improved. Translated with www.DeepL.com/Translator (free version)
{"title":"Force Characteristics and Mechanical Topology Optimization of Hydraulic Machine Structures: Statics and Dynamics","authors":"Teng Xiaolei","doi":"10.13052/ejcm2642-2085.3214","DOIUrl":"https://doi.org/10.13052/ejcm2642-2085.3214","url":null,"abstract":"In this paper, the design requirements of the hydraulic testing machine are based on the actual force conditions. Static and dynamic performance analyses of the stressed components of the hydraulic machine are carried out and the mechanical topology is optimized. Combining the static and dynamic objective functions of the structure, a fast variable density topology method is proposed, thus improving the optimization efficiency. After setting the positions of the optimized and non-optimized regions. It can be found that the optimized mechanical performance is more superior as the number of iterations increases. The results show that the stress in the strut is 175.75 MPa and the maximum stress in the upper beam structure is 43.708 MPa. The first sixth order frequency is much higher than the operating frequency of 3 Hz. The final results of the mechanical topology optimization analysis show. The optimized structure of the upper, middle and lower crossbeams resulted in a mass reduction of 38%, 36% and 5.57%. The maximum stresses in the upper and middle crossbeams were reduced by 10.33%, 8.3% and 51.8%, respectively. The deformation was reduced by 6.14% at the fastest time; the inherent frequency of the first 3 orders was increased to achieve light weight. The overall mechanical properties became better after optimization, and the dynamic and static stability of the frame was improved.\u0000Translated with www.DeepL.com/Translator (free version)","PeriodicalId":45463,"journal":{"name":"European Journal of Computational Mechanics","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49051783","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-30DOI: 10.13052/ejcm2642-2085.3213
Guo Yunhong, Zhang Shihao
Aiming at the defects of various existing displacement inverse analysis methods, using the nonlinear mapping ability of neural network and the global random search ability of genetic algorithm, this paper proposes a displacement inverse analysis method based on optimized Genetic Algorithm- Back Propagation (GA-BP) for deep foundation pit support. The method changes the method that BP algorithm relies on the guidance of gradient information to adjust the network weights, but uses the characteristics of global search of genetic algorithm to find the most suitable network connection rights and network structure, etc. to achieve the purpose of optimization. Firstly, the deformation mechanism of deep foundation pit is analyzed, its failure mode is summarized, and the calculation method of lateral rock and soil pressure is sorted out according to the code. The theory and characteristics of BP neural network and genetic algorithm are discussed, and the method of using genetic algorithm to optimize BP neural network is proposed to improve the prediction accuracy. In view of the shortcomings of GA-BP neural network prediction model in training sample pretreatment and hidden layer structure design, the optimal normalization interval was determined by correlation coefficient regression analysis, and the analytical expression of the number of neurons in hidden layer was derived by statistical principle, and the value range of the optimal number of neurons in single hidden layer was proposed. Combined with the actual engineering, the mechanical parameters inversion and displacement force inverse analysis are performed using this method, and the results show that the optimized GA-BP has higher prediction accuracy compared with BP neural network and GA-BP, and the deviation of the displacement prediction value at each depth is kept within 0.2 mm, the absolute error interval width is 0.07 mm, and the maximum relative error is 1.35% at 4.0 m depth.
针对现有各种位移逆分析方法的缺陷，利用神经网络的非线性映射能力和遗传算法的全局随机搜索能力，提出了一种基于优化遗传算法-反向传播(GA-BP)的深基坑支护位移逆分析方法。该方法改变了BP算法依赖梯度信息引导调整网络权值的方法，而是利用遗传算法全局搜索的特点，寻找最合适的网络连接权和网络结构等，达到优化的目的。首先，分析了深基坑的变形机理，总结了深基坑的破坏模式，并根据规范整理了深基坑侧向岩土压力的计算方法。讨论了BP神经网络和遗传算法的原理和特点，提出了利用遗传算法对BP神经网络进行优化以提高预测精度的方法。针对GA-BP神经网络预测模型在训练样本预处理和隐层结构设计方面的不足，通过相关系数回归分析确定最优归一化区间，利用统计原理推导出隐层神经元数的解析表达式，提出了单隐层最优神经元数的取值范围。结合工程实际，利用该方法进行了力学参数反演和位移力逆分析，结果表明:优化后的GA-BP与BP神经网络和GA-BP相比具有更高的预测精度，各深度位移预测值偏差控制在0.2 mm以内，绝对误差区间宽度为0.07 mm, 4.0 m深度最大相对误差为1.35%。
{"title":"Application of GA-BP in Displacement Force Inverse Analysis and Mechanical Parameter Inversion of Deep Foundation Pits","authors":"Guo Yunhong, Zhang Shihao","doi":"10.13052/ejcm2642-2085.3213","DOIUrl":"https://doi.org/10.13052/ejcm2642-2085.3213","url":null,"abstract":"Aiming at the defects of various existing displacement inverse analysis methods, using the nonlinear mapping ability of neural network and the global random search ability of genetic algorithm, this paper proposes a displacement inverse analysis method based on optimized Genetic Algorithm- Back Propagation (GA-BP) for deep foundation pit support. The method changes the method that BP algorithm relies on the guidance of gradient information to adjust the network weights, but uses the characteristics of global search of genetic algorithm to find the most suitable network connection rights and network structure, etc. to achieve the purpose of optimization. Firstly, the deformation mechanism of deep foundation pit is analyzed, its failure mode is summarized, and the calculation method of lateral rock and soil pressure is sorted out according to the code. The theory and characteristics of BP neural network and genetic algorithm are discussed, and the method of using genetic algorithm to optimize BP neural network is proposed to improve the prediction accuracy. In view of the shortcomings of GA-BP neural network prediction model in training sample pretreatment and hidden layer structure design, the optimal normalization interval was determined by correlation coefficient regression analysis, and the analytical expression of the number of neurons in hidden layer was derived by statistical principle, and the value range of the optimal number of neurons in single hidden layer was proposed. Combined with the actual engineering, the mechanical parameters inversion and displacement force inverse analysis are performed using this method, and the results show that the optimized GA-BP has higher prediction accuracy compared with BP neural network and GA-BP, and the deviation of the displacement prediction value at each depth is kept within 0.2 mm, the absolute error interval width is 0.07 mm, and the maximum relative error is 1.35% at 4.0 m depth.","PeriodicalId":45463,"journal":{"name":"European Journal of Computational Mechanics","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47893448","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
To analyze the rheological and mechanical properties as well as the vibration-mechanical forbidden zone effect of row pile foundations, this paper employs time-dependent modulus to examine the rheological mechanics of soil. Drawing from viscoelastic theory, we derive the expression of deformation modulus in the frequency domain to analyze the frequency dependence of the shear modulus of rheological soils. We construct a continuous medium dynamics model of the pile-soil periodic structure, taking into account soil rheology, and derive the dispersion equation of shear waves in the periodic structure using the multiple scattering method. The band gap characteristics and parameters that influence the law of shear waves in rheological soil-row pile foundations are studied through the analysis of arithmetic cases. The results show that under the loading condition, the zero-frequency shear modulus of soil is larger than the initial modulus value, and the real part of the shear modulus decreases monotonically with the increase of frequency and finally converges to the initial modulus value; under the unloading condition, the zero-frequency shear modulus of soil is smaller than the initial modulus value, and the real part of the shear modulus increases monotonically with the increase of frequency and finally converges to the initial modulus value; the larger the relaxation time of soil, the faster the convergence rate; the imaginary part of the shear modulus of soil The imaginary part of the soil shear modulus is positive under loading condition and negative under unloading condition, the value of the imaginary part increases and then decreases with increasing frequency and finally converges to 0. The imaginary part reaches the peak at the critical frequency, the larger the relaxation time the smaller the critical frequency, and the peak of the imaginary part is independent of the relaxation time. This study analyzed the dispersion curve of shear waves in a pile-soil periodic structure and found that increasing low-frequency shear wave velocity in rheological soil pile foundation shifts the band gap position to a higher frequency band, resulting in a smaller band gap width than in linear elastic soil. The relaxation time of soil affects the frequency position and width of the band gap, with larger relaxation times resulting in higher frequency positions and smaller widths. Additionally, soil rheology widens the forbidden vibration band gap of the pile periodic structure when the filling rate of the pile foundation is larger.
{"title":"Study of Rheological-Mechanical Properties and Vibration Mechanics Bandgap of Row Pile Foundation","authors":"Qiunan Chen, Zhixin Li, Xiaocheng Huang, Chen Zhang","doi":"10.13052/ejcm2642-2085.3212","DOIUrl":"https://doi.org/10.13052/ejcm2642-2085.3212","url":null,"abstract":"To analyze the rheological and mechanical properties as well as the vibration-mechanical forbidden zone effect of row pile foundations, this paper employs time-dependent modulus to examine the rheological mechanics of soil. Drawing from viscoelastic theory, we derive the expression of deformation modulus in the frequency domain to analyze the frequency dependence of the shear modulus of rheological soils. We construct a continuous medium dynamics model of the pile-soil periodic structure, taking into account soil rheology, and derive the dispersion equation of shear waves in the periodic structure using the multiple scattering method. The band gap characteristics and parameters that influence the law of shear waves in rheological soil-row pile foundations are studied through the analysis of arithmetic cases. The results show that under the loading condition, the zero-frequency shear modulus of soil is larger than the initial modulus value, and the real part of the shear modulus decreases monotonically with the increase of frequency and finally converges to the initial modulus value; under the unloading condition, the zero-frequency shear modulus of soil is smaller than the initial modulus value, and the real part of the shear modulus increases monotonically with the increase of frequency and finally converges to the initial modulus value; the larger the relaxation time of soil, the faster the convergence rate; the imaginary part of the shear modulus of soil The imaginary part of the soil shear modulus is positive under loading condition and negative under unloading condition, the value of the imaginary part increases and then decreases with increasing frequency and finally converges to 0. The imaginary part reaches the peak at the critical frequency, the larger the relaxation time the smaller the critical frequency, and the peak of the imaginary part is independent of the relaxation time. This study analyzed the dispersion curve of shear waves in a pile-soil periodic structure and found that increasing low-frequency shear wave velocity in rheological soil pile foundation shifts the band gap position to a higher frequency band, resulting in a smaller band gap width than in linear elastic soil. The relaxation time of soil affects the frequency position and width of the band gap, with larger relaxation times resulting in higher frequency positions and smaller widths. Additionally, soil rheology widens the forbidden vibration band gap of the pile periodic structure when the filling rate of the pile foundation is larger.","PeriodicalId":45463,"journal":{"name":"European Journal of Computational Mechanics","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47216537","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-05-03DOI: 10.13052/ejcm2642-2085.31563
Guoqing Huang, Na Ren, Hengbin Zheng
To analyze the coupled dynamics effects of existing railroad frame bridge structures under the action of traffic, a coupled train-ballast track-suspension bridge girder-soil dynamics model is established based on railroad large system dynamics and finite element theory. The joint ABAQUS-MATLAB simulation, time-varying coupling, and multi-step dynamic iterative solution strategies are introduced to numerically simulate the mechanical properties of existing railroad structures under the coupled effects of wind loads and traffic action. Specifically, (1) a dichotomous method is proposed to investigate the static behavior of the bridge in the bridge-forming state, and the maximum upper arch of the stiffened girder is 3.67 cm, which occurs at about 1/4 and 3/4 positions of the main span, and the lower deflection of the side span is larger, and the maximum lower deflection occurs at 11.04 cm in the span of the 110 m side span. The vertical acceleration in the span increases immediately with the maximum peak of 30 cm/s2, while the lateral acceleration is maintained within 20 cm/s22. (2) The effects of the stiffness of the rail fasteners and the bridge plate support stiffness on the dynamics were studied. (3) The results of the time-domain analysis are in general agreement with the simulation data, except for the error of the ambient vibration background existing at the peak. The correctness of the simulation model is verified.
{"title":"Structural Dynamics of Bridges Under the Coupling Effect of Windmills and Bridges","authors":"Guoqing Huang, Na Ren, Hengbin Zheng","doi":"10.13052/ejcm2642-2085.31563","DOIUrl":"https://doi.org/10.13052/ejcm2642-2085.31563","url":null,"abstract":"To analyze the coupled dynamics effects of existing railroad frame bridge structures under the action of traffic, a coupled train-ballast track-suspension bridge girder-soil dynamics model is established based on railroad large system dynamics and finite element theory. The joint ABAQUS-MATLAB simulation, time-varying coupling, and multi-step dynamic iterative solution strategies are introduced to numerically simulate the mechanical properties of existing railroad structures under the coupled effects of wind loads and traffic action. Specifically, (1) a dichotomous method is proposed to investigate the static behavior of the bridge in the bridge-forming state, and the maximum upper arch of the stiffened girder is 3.67 cm, which occurs at about 1/4 and 3/4 positions of the main span, and the lower deflection of the side span is larger, and the maximum lower deflection occurs at 11.04 cm in the span of the 110 m side span. The vertical acceleration in the span increases immediately with the maximum peak of 30 cm/s2, while the lateral acceleration is maintained within 20 cm/s22. (2) The effects of the stiffness of the rail fasteners and the bridge plate support stiffness on the dynamics were studied. (3) The results of the time-domain analysis are in general agreement with the simulation data, except for the error of the ambient vibration background existing at the peak. The correctness of the simulation model is verified.","PeriodicalId":45463,"journal":{"name":"European Journal of Computational Mechanics","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48070756","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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