Pub Date : 2024-11-21DOI: 10.1016/j.soildyn.2024.109100
Xianwei Liu , Su Chen , Lei Fu , Xiaojun Li , Fabrice Cotton
This study presents a novel framework for ground motion modelling utilizing Physics-Guided Symbolic Neural Networks (PGSNN). Symbolic neural networks offer a new method for knowledge discovery, providing a unique perspective for automatically uncovering predictive functional forms from data. This approach differs from traditional methods as it does not rely on predefined equations. Instead, it employs symbolic operators to freely combine input parameters in a high-dimensional space. This method addresses the problem of data imbalance by incorporating physical guidance to ensure that the model produces results that are consistent with established physical principles. The resulting equations align with the expectations of the engineering seismology community, particularly within the magnitude-distance ranges, where classical equations are well calibrated. The prediction performance of the PGSNN, evaluated across different intensity measures (PGA, PGV, and PSA), was assessed by calculating the residuals between measured and predicted values and their standard deviations. The predictive capability of this model was verified using new event records. The results indicate that the prediction performance of the PGSNN is comparable to those of traditional methods.
{"title":"Physics-guided symbolic neural network reveals optimal functional forms describing ground motions","authors":"Xianwei Liu , Su Chen , Lei Fu , Xiaojun Li , Fabrice Cotton","doi":"10.1016/j.soildyn.2024.109100","DOIUrl":"10.1016/j.soildyn.2024.109100","url":null,"abstract":"<div><div>This study presents a novel framework for ground motion modelling utilizing Physics-Guided Symbolic Neural Networks (PGSNN). Symbolic neural networks offer a new method for knowledge discovery, providing a unique perspective for automatically uncovering predictive functional forms from data. This approach differs from traditional methods as it does not rely on predefined equations. Instead, it employs symbolic operators to freely combine input parameters in a high-dimensional space. This method addresses the problem of data imbalance by incorporating physical guidance to ensure that the model produces results that are consistent with established physical principles. The resulting equations align with the expectations of the engineering seismology community, particularly within the magnitude-distance ranges, where classical equations are well calibrated. The prediction performance of the PGSNN, evaluated across different intensity measures (PGA, PGV, and PSA), was assessed by calculating the residuals between measured and predicted values and their standard deviations. The predictive capability of this model was verified using new event records. The results indicate that the prediction performance of the PGSNN is comparable to those of traditional methods.</div></div>","PeriodicalId":49502,"journal":{"name":"Soil Dynamics and Earthquake Engineering","volume":"188 ","pages":"Article 109100"},"PeriodicalIF":4.2,"publicationDate":"2024-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142702221","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-21DOI: 10.1016/j.soildyn.2024.109088
Weizheng Liu , Jiming Tan , Weihua Lv , Cheng Chen , Shuai Qu
To address the long-term settlement of embankments over structured soft soil during the in-service stage, artificial structured soils with different interparticle bonding strengths and initial void ratios were prepared, and repeated triaxial loading tests were conducted to investigate the effects of bonding strength, initial void ratio, stress amplitude and cycle number on the accumulative deformation characteristics. The results show that the relationship between the accumulative plastic strain and cycle number can be classified into stable, critical and destructive types, and an empirical relationship between the stress sensitivity and dynamic stress ratio is established. Furthermore, two different empirical models for accumulative plastic strain are presented that incorporate soil structure. Reasonable agreement between the model predictions and the experimental results for different natural soft soils demonstrate that the proposed models can accurately capture the accumulative deformation behaviour of structured soils. In addition, considering the accumulated plastic deformation of soil subjected to cyclic loading as static creep, a simplified method for calculating three-dimensional cyclic accumulative deformation is proposed by implementing the proposed model in a finite-element simulation utilizing an implicit stress integration algorithm. Finally, the effects of the dynamic stress level and structural strength on the accumulative deformation are analyzed. This has important implications in controlling the long-term settlement of embankment in soft soil area.
{"title":"Characteristics and predictions of accumulative deformation of structured soft soil under long-term cyclic loading","authors":"Weizheng Liu , Jiming Tan , Weihua Lv , Cheng Chen , Shuai Qu","doi":"10.1016/j.soildyn.2024.109088","DOIUrl":"10.1016/j.soildyn.2024.109088","url":null,"abstract":"<div><div>To address the long-term settlement of embankments over structured soft soil during the in-service stage, artificial structured soils with different interparticle bonding strengths and initial void ratios were prepared, and repeated triaxial loading tests were conducted to investigate the effects of bonding strength, initial void ratio, stress amplitude and cycle number on the accumulative deformation characteristics. The results show that the relationship between the accumulative plastic strain and cycle number can be classified into stable, critical and destructive types, and an empirical relationship between the stress sensitivity and dynamic stress ratio is established. Furthermore, two different empirical models for accumulative plastic strain are presented that incorporate soil structure. Reasonable agreement between the model predictions and the experimental results for different natural soft soils demonstrate that the proposed models can accurately capture the accumulative deformation behaviour of structured soils. In addition, considering the accumulated plastic deformation of soil subjected to cyclic loading as static creep, a simplified method for calculating three-dimensional cyclic accumulative deformation is proposed by implementing the proposed model in a finite-element simulation utilizing an implicit stress integration algorithm. Finally, the effects of the dynamic stress level and structural strength on the accumulative deformation are analyzed. This has important implications in controlling the long-term settlement of embankment in soft soil area.</div></div>","PeriodicalId":49502,"journal":{"name":"Soil Dynamics and Earthquake Engineering","volume":"189 ","pages":"Article 109088"},"PeriodicalIF":4.2,"publicationDate":"2024-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142720532","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-21DOI: 10.1016/j.soildyn.2024.109104
Zilan Zhong , Lingyue Xu , Chuntang Han , Junyan Han , M. Hesham El Naggar , Jinqiang Li , Xin Zhao , Huiquan Miao
Permanent ground deformation hazards, such as fault displacement, liquefaction-induced settlement, and landslides, pose a severe threat to the integrity of buried pipelines. In this study, three-dimensional numerical simulations are performed to investigate the horizontal lateral soil-pipeline interaction in medium-dense sand and to identify the failure mechanisms of the surrounding sand for different pipeline depth-diameter ratios. The ultimate bearing capacity of sand around the pipeline is evaluated for different soil failure mechanisms. Moreover, a simplified analytical model of the soil-pipeline under lateral movement is proposed based on the identified soil failure mechanisms. Consequently, an analytical solution for the ultimate bearing capacity of the soil under lateral motion of the buried pipeline is derived based on the limit-state equilibrium. The results obtained from the analytical solution indicate that at the limit state, the soil around a shallowly buried pipeline forms a ruptured surface extending to the ground surface with a logarithmic spiral failure surface. The lateral ultimate bearing capacity increases as the pipeline burial depth-diameter ratio increases until it reaches a constant value at a certain critical depth-diameter ratio. As the pipeline depth-diameter ratio increases, the pipeline displacement that causes shear failure of the soil also gradually increases. It is demonstrated that the proposed analytical solution well predicts the soil ultimate lateral bearing capacity for pipelines installed shallowly in medium and dense sand. Furthermore, the ultimate bearing capacity of pipelines in sand is evaluated by Chinese and some international codes. The disparity between results from different codes is attributed to the variation in empirical lateral bearing capacity coefficients used in the respective codes.
{"title":"Ultimate bearing capacity of sand under lateral movement of buried pipelines","authors":"Zilan Zhong , Lingyue Xu , Chuntang Han , Junyan Han , M. Hesham El Naggar , Jinqiang Li , Xin Zhao , Huiquan Miao","doi":"10.1016/j.soildyn.2024.109104","DOIUrl":"10.1016/j.soildyn.2024.109104","url":null,"abstract":"<div><div>Permanent ground deformation hazards, such as fault displacement, liquefaction-induced settlement, and landslides, pose a severe threat to the integrity of buried pipelines. In this study, three-dimensional numerical simulations are performed to investigate the horizontal lateral soil-pipeline interaction in medium-dense sand and to identify the failure mechanisms of the surrounding sand for different pipeline depth-diameter ratios. The ultimate bearing capacity of sand around the pipeline is evaluated for different soil failure mechanisms. Moreover, a simplified analytical model of the soil-pipeline under lateral movement is proposed based on the identified soil failure mechanisms. Consequently, an analytical solution for the ultimate bearing capacity of the soil under lateral motion of the buried pipeline is derived based on the limit-state equilibrium. The results obtained from the analytical solution indicate that at the limit state, the soil around a shallowly buried pipeline forms a ruptured surface extending to the ground surface with a logarithmic spiral failure surface. The lateral ultimate bearing capacity increases as the pipeline burial depth-diameter ratio increases until it reaches a constant value at a certain critical depth-diameter ratio. As the pipeline depth-diameter ratio increases, the pipeline displacement that causes shear failure of the soil also gradually increases. It is demonstrated that the proposed analytical solution well predicts the soil ultimate lateral bearing capacity for pipelines installed shallowly in medium and dense sand. Furthermore, the ultimate bearing capacity of pipelines in sand is evaluated by Chinese and some international codes. The disparity between results from different codes is attributed to the variation in empirical lateral bearing capacity coefficients used in the respective codes.</div></div>","PeriodicalId":49502,"journal":{"name":"Soil Dynamics and Earthquake Engineering","volume":"188 ","pages":"Article 109104"},"PeriodicalIF":4.2,"publicationDate":"2024-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142702220","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-20DOI: 10.1016/j.soildyn.2024.109091
Hongjun He , Xiaohua Ke , Yu Miao , Chenxi Miao
Previous research on site response has primarily focused on reproducing and predicting ground motions recorded by vertical seismic arrays. This study evaluated the ability to reproduce and predict small-strain site response at the Treasure Island Downhole Array and Delaney Park Downhole Array using inverse soil dynamic parameters. First, parameters such as seismic wave velocity profiles and Rayleigh damping ratios were obtained through seismic interferometry and spectral ratio methods based on the earthquake records. Subsequently, the validity and reliability of these inverse soil dynamic parameters were evaluated by comparing the simulated and observed ground responses. Finally, the inverse method was compared with other methods considering spatial variability in one-dimensional site response analysis. Quantitative comparisons show that the inverse method effectively predicts and reproduces site response and outperforms the traditional method relying on the single borehole shear wave velocity profile and damping ratio from empirical model. Moreover, the inverse method better captures spatial variability at the Delaney Park Downhole Array.
{"title":"Investigating small-strain site response using inverse soil dynamic parameters from downhole arrays","authors":"Hongjun He , Xiaohua Ke , Yu Miao , Chenxi Miao","doi":"10.1016/j.soildyn.2024.109091","DOIUrl":"10.1016/j.soildyn.2024.109091","url":null,"abstract":"<div><div>Previous research on site response has primarily focused on reproducing and predicting ground motions recorded by vertical seismic arrays. This study evaluated the ability to reproduce and predict small-strain site response at the Treasure Island Downhole Array and Delaney Park Downhole Array using inverse soil dynamic parameters. First, parameters such as seismic wave velocity profiles and Rayleigh damping ratios were obtained through seismic interferometry and spectral ratio methods based on the earthquake records. Subsequently, the validity and reliability of these inverse soil dynamic parameters were evaluated by comparing the simulated and observed ground responses. Finally, the inverse method was compared with other methods considering spatial variability in one-dimensional site response analysis. Quantitative comparisons show that the inverse method effectively predicts and reproduces site response and outperforms the traditional method relying on the single borehole shear wave velocity profile and damping ratio from empirical model. Moreover, the inverse method better captures spatial variability at the Delaney Park Downhole Array.</div></div>","PeriodicalId":49502,"journal":{"name":"Soil Dynamics and Earthquake Engineering","volume":"188 ","pages":"Article 109091"},"PeriodicalIF":4.2,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142702214","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-20DOI: 10.1016/j.soildyn.2024.109086
Wenhao Zhang , Rui Sun , Pinghe Ni , Mi Zhao , M. Hesham El Naggar , Xiuli Du
The seismic performance of underground structures is strongly influenced by the characteristics of both the surrounding soil and the earthquake. In contrast to traditional deterministic analysis methods, this study uses a stochastic analysis approach to investigate the effect of uncertainties in nonlinear soil characteristics, shear wave velocity, density, and earthquake randomness on the response of underground stations. The equivalent linearization method is employed to approximate the nonlinear behavior of the soil. The soil was modeled using a linear elastic constitutive model combined with Rayleigh damping in the finite element model. Inter-story displacements are used to determine structural damage. Probabilistic analysis methods are used to obtain their statistical characteristics, and the probability of failure is calculated. The results show that, according to single parameter analysis, random ground motion results in the greatest probability of exceeding the threshold (PET), while ground shear wave velocity significantly affects the coefficient of variation (COV), and the effect of density is the smallest. The study also found that when soil nonlinearity, shear wave velocity, and random ground motion are considered simultaneously, the range, mean, standard deviation, and COV of interstory displacement all increase significantly, but the PET slightly decreases. In summary, the analysis results indicate that random ground motion has the greatest impact on interstory displacement, followed by shear wave velocity, with nonlinear soil characteristics having a smaller effect, and density the least. Therefore, the impact of various uncertainties should be fully considered in the analysis of underground structures, especially random ground motion and shear wave velocity.
地下结构的抗震性能受周围土壤特性和地震的影响很大。与传统的确定性分析方法不同，本研究采用随机分析方法来研究非线性土壤特性、剪切波速度、密度和地震随机性等不确定性因素对地下车站响应的影响。采用等效线性化方法来近似分析土壤的非线性行为。在有限元模型中使用线性弹性构成模型结合瑞利阻尼对土壤进行建模。层间位移用于确定结构损伤。采用概率分析方法获得其统计特征，并计算出破坏概率。结果表明，根据单参数分析，随机地面运动导致超过临界值的概率（PET）最大，而地面剪切波速度对变异系数（COV）有显著影响，密度的影响最小。研究还发现，当同时考虑土壤非线性、剪切波速度和随机地面运动时，层间位移的范围、平均值、标准偏差和 COV 都会显著增加，但 PET 会略有下降。总之，分析结果表明，随机地面运动对层间位移的影响最大，其次是剪切波速，非线性土壤特性的影响较小，而密度的影响最小。因此，在地下结构分析中应充分考虑各种不确定因素的影响，尤其是随机地面运动和剪切波速。
{"title":"Quantitative analysis of subway station seismic deformation under random earthquakes and uncertain soil properties using the equivalent linearization method","authors":"Wenhao Zhang , Rui Sun , Pinghe Ni , Mi Zhao , M. Hesham El Naggar , Xiuli Du","doi":"10.1016/j.soildyn.2024.109086","DOIUrl":"10.1016/j.soildyn.2024.109086","url":null,"abstract":"<div><div>The seismic performance of underground structures is strongly influenced by the characteristics of both the surrounding soil and the earthquake. In contrast to traditional deterministic analysis methods, this study uses a stochastic analysis approach to investigate the effect of uncertainties in nonlinear soil characteristics, shear wave velocity, density, and earthquake randomness on the response of underground stations. The equivalent linearization method is employed to approximate the nonlinear behavior of the soil. The soil was modeled using a linear elastic constitutive model combined with Rayleigh damping in the finite element model. Inter-story displacements are used to determine structural damage. Probabilistic analysis methods are used to obtain their statistical characteristics, and the probability of failure is calculated. The results show that, according to single parameter analysis, random ground motion results in the greatest probability of exceeding the threshold (PET), while ground shear wave velocity significantly affects the coefficient of variation (COV), and the effect of density is the smallest. The study also found that when soil nonlinearity, shear wave velocity, and random ground motion are considered simultaneously, the range, mean, standard deviation, and COV of interstory displacement all increase significantly, but the PET slightly decreases. In summary, the analysis results indicate that random ground motion has the greatest impact on interstory displacement, followed by shear wave velocity, with nonlinear soil characteristics having a smaller effect, and density the least. Therefore, the impact of various uncertainties should be fully considered in the analysis of underground structures, especially random ground motion and shear wave velocity.</div></div>","PeriodicalId":49502,"journal":{"name":"Soil Dynamics and Earthquake Engineering","volume":"188 ","pages":"Article 109086"},"PeriodicalIF":4.2,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142702217","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-19DOI: 10.1016/j.soildyn.2024.109093
Ziqian Wang , Kenichi Nakano , Jikai Sun , Eri Ito , Hiroshi Kawase
A new methodology, including a mature algorithm with adjustments and a new target for the subsurface sedimentary inversion problem was introduced. This study adopted the particle swarm optimization (PSO) algorithm as a global optimization algorithm. PSO incorporates the patterns embedded in natural bird foraging behaviors to invert the subsurface S-wave velocity structure. Using the concept of particle velocity, PSO involves particle individual inertia, individual experience, and social experience of the swarm, pursuing the global optimum solution in a multidimensional abstract space. The inversion target was the horizontal site amplification factor (HSAF), which was extracted using the generalized inversion technique for the observed strong ground motions. HSAF is an appropriate target in the S-wave velocity structure inversion problem as it directly represents the site response to the incident S-wave at the seismological bedrock. We validated the convergence ability of the PSO and applied it to three field earthquake observation stations. From the perspective of the misfit between the target and estimation velocity profile, improvements exceeding 95 % and 70 % can be confirmed in the validation case and practical applications, respectively. The use of HSAF as the target and PSO as the algorithm is currently limited but is demonstrably effective. This study introduces a methodology that has significant potential for solving velocity structure inversion problems at subsurface levels.
针对地下沉积反演问题引入了一种新方法，包括对成熟算法进行调整和新目标。本研究采用粒子群优化算法（PSO）作为全局优化算法。PSO 结合了自然界鸟类觅食行为中蕴含的模式来反演地下 S 波速度结构。PSO 利用粒子速度的概念，将粒子群的个体惯性、个体经验和社会经验结合起来，在多维抽象空间中追求全局最优解。反演目标是水平场地放大系数（HSAF），它是利用观测到的强地面运动的广义反演技术提取的。在 S 波速度结构反演问题中，HSAF 是一个合适的目标，因为它直接代表了地震基岩对入射 S 波的场地响应。我们验证了 PSO 的收敛能力，并将其应用于三个现场地震观测站。从目标速度剖面与估计速度剖面之间的误差角度来看，验证案例和实际应用中的改进分别超过了 95% 和 70%。使用 HSAF 作为目标和 PSO 作为算法目前还很有限，但已证明是有效的。本研究介绍了一种在解决地下速度结构反演问题方面具有巨大潜力的方法。
{"title":"Subsurface S-wave velocity structure inversion using particle swarm optimization based on horizontal site response extracted using generalized inversion technique","authors":"Ziqian Wang , Kenichi Nakano , Jikai Sun , Eri Ito , Hiroshi Kawase","doi":"10.1016/j.soildyn.2024.109093","DOIUrl":"10.1016/j.soildyn.2024.109093","url":null,"abstract":"<div><div>A new methodology, including a mature algorithm with adjustments and a new target for the subsurface sedimentary inversion problem was introduced. This study adopted the particle swarm optimization (PSO) algorithm as a global optimization algorithm. PSO incorporates the patterns embedded in natural bird foraging behaviors to invert the subsurface S-wave velocity structure. Using the concept of particle velocity, PSO involves particle individual inertia, individual experience, and social experience of the swarm, pursuing the global optimum solution in a multidimensional abstract space. The inversion target was the horizontal site amplification factor (HSAF), which was extracted using the generalized inversion technique for the observed strong ground motions. HSAF is an appropriate target in the S-wave velocity structure inversion problem as it directly represents the site response to the incident S-wave at the seismological bedrock. We validated the convergence ability of the PSO and applied it to three field earthquake observation stations. From the perspective of the misfit between the target and estimation velocity profile, improvements exceeding 95 % and 70 % can be confirmed in the validation case and practical applications, respectively. The use of HSAF as the target and PSO as the algorithm is currently limited but is demonstrably effective. This study introduces a methodology that has significant potential for solving velocity structure inversion problems at subsurface levels.</div></div>","PeriodicalId":49502,"journal":{"name":"Soil Dynamics and Earthquake Engineering","volume":"188 ","pages":"Article 109093"},"PeriodicalIF":4.2,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142702215","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-19DOI: 10.1016/j.soildyn.2024.109089
Jun Shen , Xiaohua Bao , Junhong Li , Xiangsheng Chen , Hongzhi Cui
The segment joints of a shield tunnel are susceptible to deformation and leakage during seismic events. In liquefiable strata, opened joints can form seepage channels, which accelerate the dissipation of pore pressure. This study explores the interaction mechanism between tunnel structure with significant segment joints deformation and liquefiable strata under earthquakes, considering the multi-joint characteristics of a shield tunnel. First, shaking table tests were conducted to examine the dynamic characteristics of a tunnel structure with multiple joints in liquefiable strata. Based on the measured data from these tests, an optimal marginal distribution was selected from four different distribution types based on the measured values of the test results. Subsequently, a two-dimensional probability distribution model of dynamic response factors was established using Copula theory to analyse the relationship between excess pore water pressure (EPWP) dissipation and tunnel radial deformation. The correlation between EPWP dissipation and tunnel radial deformation with joints opening in the liquefiable strata was clarified. The results reveal significant differences in EPWP dissipation across different positions of the tunnel. The Gaussian Copula method effectively fits the EPWP distribution and tunnel radial deformation, indicating a positive correlation between EPWP dissipation and joints deformation. The formation of new seepage channels at the tunnel joints exacerbates EPWP dissipation. The developed probability distribution model provides a new approach for studying the dynamic response between tunnel and liquefiable soil.
{"title":"Study on the mechanism of EPWP dissipation at the joints of shield tunnel in liquefiable strata during seismic events","authors":"Jun Shen , Xiaohua Bao , Junhong Li , Xiangsheng Chen , Hongzhi Cui","doi":"10.1016/j.soildyn.2024.109089","DOIUrl":"10.1016/j.soildyn.2024.109089","url":null,"abstract":"<div><div>The segment joints of a shield tunnel are susceptible to deformation and leakage during seismic events. In liquefiable strata, opened joints can form seepage channels, which accelerate the dissipation of pore pressure. This study explores the interaction mechanism between tunnel structure with significant segment joints deformation and liquefiable strata under earthquakes, considering the multi-joint characteristics of a shield tunnel. First, shaking table tests were conducted to examine the dynamic characteristics of a tunnel structure with multiple joints in liquefiable strata. Based on the measured data from these tests, an optimal marginal distribution was selected from four different distribution types based on the measured values of the test results. Subsequently, a two-dimensional probability distribution model of dynamic response factors was established using Copula theory to analyse the relationship between excess pore water pressure (<em>EPWP</em>) dissipation and tunnel radial deformation. The correlation between <em>EPWP</em> dissipation and tunnel radial deformation with joints opening in the liquefiable strata was clarified. The results reveal significant differences in <em>EPWP</em> dissipation across different positions of the tunnel. The Gaussian Copula method effectively fits the <em>EPWP</em> distribution and tunnel radial deformation, indicating a positive correlation between <em>EPWP</em> dissipation and joints deformation. The formation of new seepage channels at the tunnel joints exacerbates EPWP dissipation. The developed probability distribution model provides a new approach for studying the dynamic response between tunnel and liquefiable soil.</div></div>","PeriodicalId":49502,"journal":{"name":"Soil Dynamics and Earthquake Engineering","volume":"188 ","pages":"Article 109089"},"PeriodicalIF":4.2,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142702218","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-19DOI: 10.1016/j.soildyn.2024.109098
Prerana Krishnaraj, Gali Madhavi Latha
Geocells have become an integral part of many geosystems like road and railway embankments, retaining walls and foundations, attributed to their multiple merits in terms of stability and strength, but their contributions towards liquefaction mitigation are unknown. The present study aims to understand the role of geocell reinforcement on the liquefaction and post-liquefaction shear response of saturated sands through monotonic and cyclic triaxial tests. Low-strength geocells of required physical and mechanical properties were fabricated through ultrasonic welding of 3D printed polypropylene (PP) sheets. The liquefaction benefits of including a single geocell in sand were quantified in terms of the reduction in pore water pressure, retardation in stiffness degradation and delay in the retardation of effective stress. In general, the inclusion of geocells delayed liquefaction, with higher beneficial effects at lower initial confining pressure, higher cyclic strain amplitude and higher cyclic loading frequency. The maximum benefit measured in terms of percentage rise in the number of cycles needed to liquefy was calculated to be about 230 %. Geocell reinforcement also helped in the quick regain of post-liquefaction shear strength and stiffness.
{"title":"Quantitative benefits of geocells in controlling liquefaction in sands","authors":"Prerana Krishnaraj, Gali Madhavi Latha","doi":"10.1016/j.soildyn.2024.109098","DOIUrl":"10.1016/j.soildyn.2024.109098","url":null,"abstract":"<div><div>Geocells have become an integral part of many geosystems like road and railway embankments, retaining walls and foundations, attributed to their multiple merits in terms of stability and strength, but their contributions towards liquefaction mitigation are unknown. The present study aims to understand the role of geocell reinforcement on the liquefaction and post-liquefaction shear response of saturated sands through monotonic and cyclic triaxial tests. Low-strength geocells of required physical and mechanical properties were fabricated through ultrasonic welding of 3D printed polypropylene (PP) sheets. The liquefaction benefits of including a single geocell in sand were quantified in terms of the reduction in pore water pressure, retardation in stiffness degradation and delay in the retardation of effective stress. In general, the inclusion of geocells delayed liquefaction, with higher beneficial effects at lower initial confining pressure, higher cyclic strain amplitude and higher cyclic loading frequency. The maximum benefit measured in terms of percentage rise in the number of cycles needed to liquefy was calculated to be about 230 %. Geocell reinforcement also helped in the quick regain of post-liquefaction shear strength and stiffness.</div></div>","PeriodicalId":49502,"journal":{"name":"Soil Dynamics and Earthquake Engineering","volume":"188 ","pages":"Article 109098"},"PeriodicalIF":4.2,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142702219","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-18DOI: 10.1016/j.soildyn.2024.109094
Qingfei Luo, Jingru An, Zhengzheng Wang
Near-fault fling-step ground motions (NFFS-GMs) are known to cause significant permanent ground displacements, resulting in greater structural damage for long-period flexible structures compared to far-field ground motions. Furthermore, even during the same seismic event, the pulse parameters—such as permanent ground displacements and pulse period —can vary considerably. Despite their importance, research on stochastic NFFS-GMs remains limited. To address this gap, this paper proposes a method for synthesizing the time-frequency non-stationary stochastic near-fault fling-step ground motion for a specific seismic scenario. Firstly, we employ the discrete wavelet transform (DWT) method, utilizing five mother wavelet functions (MWFs) to analyze 210 Chi-Chi ground motions. This analysis identifies 41 valid NFFS-GMs. The effectiveness of the identification method is validated by comparing the displacement time histories of the original ground motion. Pulse parameters are subsequently derived using the fling-step (FS) pulse model proposed by Abrahamson, in conjunction with the nonlinear least-squares method. A regression model correlating pulse parameters with the seismological parameter of the fault distance R is then developed through Pearson correlation analysis and the nonlinear least-squares method. The residuals of the regression model and are treated as random variables, and their probability distributions are determined. After that, a new stochastic pulse model is introduced to simulate low-frequency ground motions, while a time-frequency non-stationary model is used to simulate high-frequency ground motions. These components are synthesized in the frequency domain to obtain the time-frequency non-stationary stochastic near-fault fling-step ground motion (TFNS-SNFFS-GM) via inverse Fourier transform. Finally, the effectiveness of the proposed method is confirmed by comparing the response spectrum of the synthesized ground motion with that of actual NFFS-GMs.
{"title":"Synthesis of the time-frequency non-stationary stochastic near-fault fling-step ground motion based on time-frequency non-stationary ground motion model and stochastic pulse model","authors":"Qingfei Luo, Jingru An, Zhengzheng Wang","doi":"10.1016/j.soildyn.2024.109094","DOIUrl":"10.1016/j.soildyn.2024.109094","url":null,"abstract":"<div><div>Near-fault fling-step ground motions (NFFS-GMs) are known to cause significant permanent ground displacements, resulting in greater structural damage for long-period flexible structures compared to far-field ground motions. Furthermore, even during the same seismic event, the pulse parameters—such as permanent ground displacements <span><math><mrow><msub><mi>D</mi><mrow><mi>s</mi><mi>i</mi><mi>t</mi><mi>e</mi></mrow></msub></mrow></math></span> and pulse period <span><math><mrow><msub><mi>T</mi><mi>p</mi></msub></mrow></math></span>—can vary considerably. Despite their importance, research on stochastic NFFS-GMs remains limited. To address this gap, this paper proposes a method for synthesizing the time-frequency non-stationary stochastic near-fault fling-step ground motion for a specific seismic scenario. Firstly, we employ the discrete wavelet transform (DWT) method, utilizing five mother wavelet functions (MWFs) to analyze 210 Chi-Chi ground motions. This analysis identifies 41 valid NFFS-GMs. The effectiveness of the identification method is validated by comparing the displacement time histories of the original ground motion. Pulse parameters are subsequently derived using the fling-step (FS) pulse model proposed by Abrahamson, in conjunction with the nonlinear least-squares method. A regression model correlating pulse parameters with the seismological parameter of the fault distance <em>R</em> is then developed through Pearson correlation analysis and the nonlinear least-squares method. The residuals of the regression model <span><math><mrow><msub><mi>σ</mi><mrow><mi>ln</mi><mspace></mspace><msub><mi>D</mi><mrow><mi>s</mi><mi>i</mi><mi>t</mi><mi>e</mi></mrow></msub></mrow></msub></mrow></math></span> and <span><math><mrow><msub><mi>T</mi><mi>p</mi></msub></mrow></math></span> are treated as random variables, and their probability distributions are determined. After that, a new stochastic pulse model is introduced to simulate low-frequency ground motions, while a time-frequency non-stationary model is used to simulate high-frequency ground motions. These components are synthesized in the frequency domain to obtain the time-frequency non-stationary stochastic near-fault fling-step ground motion (TFNS-SNFFS-GM) via inverse Fourier transform. Finally, the effectiveness of the proposed method is confirmed by comparing the response spectrum of the synthesized ground motion with that of actual NFFS-GMs.</div></div>","PeriodicalId":49502,"journal":{"name":"Soil Dynamics and Earthquake Engineering","volume":"188 ","pages":"Article 109094"},"PeriodicalIF":4.2,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142700967","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-18DOI: 10.1016/j.soildyn.2024.109087
Zhongwei Gao , Xiaobing Yang , Jinfang Zhang , Hongyuan Tang , Yue Du , Shiyu Zhao
Based on detailed data collected on-site, including structural construction, cross-sectional dimensions, and material properties, this paper establishes a refined three-dimensional solid initial numerical model (INM) of the Jiufeng Temple Ancient Masonry Pagoda using the ABAQUS finite element software. On the basis of the measured modal characteristics (frequency, vibration mode, and damping ratio) of the ancient masonry pagoda, a modified numerical model (MNM) was obtained by adjusting the key parameters (damping ratio, Rayleigh damping coefficients, elastic modulus, and material density) of the initial numerical model. Based on the modified numerical model, five actual strong earthquake records were input to calculate the seismic response of the ancient masonry pagoda. The seismic failure mechanism of the ancient masonry pagoda, as well as the distribution characteristics of the principal tensile stress and seismic weak-layers were analyzed. The results indicate that the stiffness and mass distribution of the ancient masonry pagoda are consistent along its height, and the deformation at the top of the ancient masonry pagoda is significant under seismic action. The results obtained from the initial numerical model are more conservative, with the maximum storey drift being 19 %, 40 %, and 27 % larger than those of the modified numerical model under minor earthquakes (with a 63 % probability of exceedance in 50 years, also called frequently occurring earthquakes), moderate earthquakes (with a 10 % probability of exceedance in 50 years), and major earthquakes (with a 2 % probability of exceedance in 50 years, also called rarely occurring earthquakes), respectively. Under the action of major earthquakes, the upper portion of the Jiufeng Temple ancient masonry Pagoda, particularly above the 9th floor, may suffer severe damage. The 10th, 11th, and 12th floors are identified as the weak-layers of the ancient masonry pagoda, and the weak-layers determination from the modified numerical model are consistent with the results of standard calculations. The method proposed in this paper can provide technical support for the seismic protection of ancient masonry pagodas.
{"title":"Modal modification based analysis of seismic performance of the Jiufeng Temple Ancient Masonry Pagoda","authors":"Zhongwei Gao , Xiaobing Yang , Jinfang Zhang , Hongyuan Tang , Yue Du , Shiyu Zhao","doi":"10.1016/j.soildyn.2024.109087","DOIUrl":"10.1016/j.soildyn.2024.109087","url":null,"abstract":"<div><div>Based on detailed data collected on-site, including structural construction, cross-sectional dimensions, and material properties, this paper establishes a refined three-dimensional solid initial numerical model (INM) of the Jiufeng Temple Ancient Masonry Pagoda using the ABAQUS finite element software. On the basis of the measured modal characteristics (frequency, vibration mode, and damping ratio) of the ancient masonry pagoda, a modified numerical model (MNM) was obtained by adjusting the key parameters (damping ratio, Rayleigh damping coefficients, elastic modulus, and material density) of the initial numerical model. Based on the modified numerical model, five actual strong earthquake records were input to calculate the seismic response of the ancient masonry pagoda. The seismic failure mechanism of the ancient masonry pagoda, as well as the distribution characteristics of the principal tensile stress and seismic weak-layers were analyzed. The results indicate that the stiffness and mass distribution of the ancient masonry pagoda are consistent along its height, and the deformation at the top of the ancient masonry pagoda is significant under seismic action. The results obtained from the initial numerical model are more conservative, with the maximum storey drift being 19 %, 40 %, and 27 % larger than those of the modified numerical model under minor earthquakes (with a 63 % probability of exceedance in 50 years, also called frequently occurring earthquakes), moderate earthquakes (with a 10 % probability of exceedance in 50 years), and major earthquakes (with a 2 % probability of exceedance in 50 years, also called rarely occurring earthquakes), respectively. Under the action of major earthquakes, the upper portion of the Jiufeng Temple ancient masonry Pagoda, particularly above the 9th floor, may suffer severe damage. The 10th, 11th, and 12th floors are identified as the weak-layers of the ancient masonry pagoda, and the weak-layers determination from the modified numerical model are consistent with the results of standard calculations. The method proposed in this paper can provide technical support for the seismic protection of ancient masonry pagodas.</div></div>","PeriodicalId":49502,"journal":{"name":"Soil Dynamics and Earthquake Engineering","volume":"188 ","pages":"Article 109087"},"PeriodicalIF":4.2,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142700966","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
扫码关注我们
求助内容：
应助结果提醒方式：
京公网安备 11010802042870号