Pub Date : 2024-11-12DOI: 10.1016/j.soildyn.2024.109066
Shaoyuan Zhang , Hetao Hou , Yi Liu , Junjie Wang , Chunxue Dai , Bing Qu , Xinrui Fu
This paper aims to propose a novel self-centering beam-to-brace link with examined Shape Memory Alloy (SMA) based apparatuses to improve the seismic resilience of steel frames. Based on the past experimental data, a three-dimensional computer model of the proposed link was established to simulate the nonlinear hysteretic behavior. The results showed that the proposed link could realize the perceived advantages. A simplified Finite Element (FE) model was developed and validated via the comparison with the computer model. A 3-story and a 9-story representative building were rehabilitated with the proposed link. The Nonlinear Response History Analyses (NRHAs) were conducted on the original and rehabilitated systems to evaluate their seismic performance comparatively. To achieve a fair comparison, the original and rehabilitated systems had the proximate vibration periods and the same flexural strength under a roof drift ratio of 2 %. Compared with the original systems, the corresponding rehabilitated systems exhibited equivalent performance of transient inter-story displacement, significant advantages in eliminating residual deformation, and slight disadvantages in limiting floor acceleration. A comprehensive measure was developed and revealed the rehabilitated systems achieved superior seismic overall performance compared to the original systems.
{"title":"Seismic performance enhancement for low-rise and mid-rise steel frames using novel self-centering beam-to-brace links","authors":"Shaoyuan Zhang , Hetao Hou , Yi Liu , Junjie Wang , Chunxue Dai , Bing Qu , Xinrui Fu","doi":"10.1016/j.soildyn.2024.109066","DOIUrl":"10.1016/j.soildyn.2024.109066","url":null,"abstract":"<div><div>This paper aims to propose a novel self-centering beam-to-brace link with examined Shape Memory Alloy (SMA) based apparatuses to improve the seismic resilience of steel frames. Based on the past experimental data, a three-dimensional computer model of the proposed link was established to simulate the nonlinear hysteretic behavior. The results showed that the proposed link could realize the perceived advantages. A simplified Finite Element (FE) model was developed and validated via the comparison with the computer model. A 3-story and a 9-story representative building were rehabilitated with the proposed link. The Nonlinear Response History Analyses (NRHAs) were conducted on the original and rehabilitated systems to evaluate their seismic performance comparatively. To achieve a fair comparison, the original and rehabilitated systems had the proximate vibration periods and the same flexural strength under a roof drift ratio of 2 %. Compared with the original systems, the corresponding rehabilitated systems exhibited equivalent performance of transient inter-story displacement, significant advantages in eliminating residual deformation, and slight disadvantages in limiting floor acceleration. A comprehensive measure was developed and revealed the rehabilitated systems achieved superior seismic overall performance compared to the original systems.</div></div>","PeriodicalId":49502,"journal":{"name":"Soil Dynamics and Earthquake Engineering","volume":"188 ","pages":"Article 109066"},"PeriodicalIF":4.2,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659648","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 : 2024-11-12DOI: 10.1016/j.soildyn.2024.109073
Bo He , Yuanming Lai , Lizhou Wu , Shuairun Zhu , Xu Li
The interaction between surface irregularities and underground tunnels has notable effect on seismic waves, resulting in amplification or attenuation of ground motions. However, previous studies for scattering issue induced by the interaction between irregular topographies and understructures were only based on the assumption of plane shear horizontal (SH) waves. Actually, the significance of source effects on topographic amplification cannot be underestimated. Meanwhile, the thickness and material damping of local alluvium can exert momentous influence on ground motions. In this study, a series solution is proposed to tackle the scattering phenomenon caused by a partially filled semi-circular alluvial valley with a lined tunnel under cylindrical SH waves, and the impact of source distance on the ground motions of the irregular topography with a tunnel is revealed for the first time. Firstly, the wave-function expansion approach and classical mirror image method are developed to constructive wave-function expressions in different polar coordinate systems. Then, applying the appropriate Graf's addition formula, it becomes possible to unify the coordinate systems for different subregions. Furthermore, according to continuity conditions of stress and displacement, the region-matching technique is adopted to determine the unknown coefficients of the algebraic equations. Finally, to illustrate the interaction between a partially filled alluvial valley and a lined tunnel on ground motions, a comprehensive parametric analysis is performed in both the frequency and time domains. A significant finding is that ground motions of combined topography is affected by the source location, and the source distance cannot be disregarded unless the source distance surpasses 100-time valley width. This indicates the need to closely examine how the source location influences the amplification effect due to combined topography, particularly when the source is near the terrain.
地表不规则地形与地下隧道之间的相互作用会对地震波产生显著影响，导致地面运动的放大或衰减。然而，以往对不规则地形与地下结构相互作用引起的散射问题的研究仅基于平面剪切水平（SH）波的假设。实际上，震源效应对地形放大的影响不容低估。同时，当地冲积层的厚度和材料阻尼也会对地面运动产生巨大影响。本研究针对带衬砌隧道的部分充填半圆形冲积谷地在圆柱 SH 波作用下产生的散射现象，提出了一种系列解法，首次揭示了源距对带隧道不规则地形地面运动的影响。首先，建立了波函数展开方法和经典镜像法，以构造不同极坐标系下的波函数表达式。然后，应用适当的格拉夫加法公式，可以统一不同子区域的坐标系。此外，根据应力和位移的连续性条件，采用区域匹配技术确定代数方程的未知系数。最后，为了说明部分充填的冲积河谷和衬砌隧道之间的相互作用对地面运动的影响，在频域和时域进行了全面的参数分析。一个重要的发现是，组合地形的地面运动受到震源位置的影响，除非震源距离超过 100 倍的谷宽，否则不能忽略震源距离。这表明有必要仔细研究震源位置如何影响组合地形引起的放大效应，特别是当震源靠近地形时。
{"title":"Ground motions around a partially filled semi-circular alluvial valley with a lined tunnel under cylindrical SH waves","authors":"Bo He , Yuanming Lai , Lizhou Wu , Shuairun Zhu , Xu Li","doi":"10.1016/j.soildyn.2024.109073","DOIUrl":"10.1016/j.soildyn.2024.109073","url":null,"abstract":"<div><div>The interaction between surface irregularities and underground tunnels has notable effect on seismic waves, resulting in amplification or attenuation of ground motions. However, previous studies for scattering issue induced by the interaction between irregular topographies and understructures were only based on the assumption of plane shear horizontal (SH) waves. Actually, the significance of source effects on topographic amplification cannot be underestimated. Meanwhile, the thickness and material damping of local alluvium can exert momentous influence on ground motions. In this study, a series solution is proposed to tackle the scattering phenomenon caused by a partially filled semi-circular alluvial valley with a lined tunnel under cylindrical SH waves, and the impact of source distance on the ground motions of the irregular topography with a tunnel is revealed for the first time. Firstly, the wave-function expansion approach and classical mirror image method are developed to constructive wave-function expressions in different polar coordinate systems. Then, applying the appropriate Graf's addition formula, it becomes possible to unify the coordinate systems for different subregions. Furthermore, according to continuity conditions of stress and displacement, the region-matching technique is adopted to determine the unknown coefficients of the algebraic equations. Finally, to illustrate the interaction between a partially filled alluvial valley and a lined tunnel on ground motions, a comprehensive parametric analysis is performed in both the frequency and time domains. A significant finding is that ground motions of combined topography is affected by the source location, and the source distance cannot be disregarded unless the source distance surpasses 100-time valley width. This indicates the need to closely examine how the source location influences the amplification effect due to combined topography, particularly when the source is near the terrain.</div></div>","PeriodicalId":49502,"journal":{"name":"Soil Dynamics and Earthquake Engineering","volume":"188 ","pages":"Article 109073"},"PeriodicalIF":4.2,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659712","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 : 2024-11-12DOI: 10.1016/j.soildyn.2024.109081
Lei Fu , Su Chen , Zhinan Xie , Suyang Wang , Junlei Chen , Xiaojun Li
Despite their crucial importance for marine engineering, the nonlinear seismic response characteristics of offshore sites remain poorly understood. Consequently, simulating ground-motion at offshore sites poses a significant challenge. To address this, this study begins with a dataset comprising stress drops of 70 earthquakes, region-specific quality factors, and linear site amplification factors (AFs) of six offshore stations in Sagami Bay, Japan, obtained using the generalized inversion technique (GIT). Then, by incorporating additional offshore accelerograms with focal depths up to 333 km and peak ground accelerations (PGAs) ranging from 0.2 to 4.2 m/s2, we delve deeper into the effects of nonlinear site behaviors on the high-frequency attenuation parameter (κ0) and AFs, respectively. A counterintuitive decrease in κ0 was observed as the peak ground acceleration (PGA) reached 0.5–0.8 m/s2, echoing similar observations from previous studies on KiK-net stations. Our results indicate that the high-frequency attenuation characteristics of offshore sites vary under strong motions, potentially attributable to the nonlinear evolution of the frequency-independent quality factor and S-wave velocity within near-surface sediments. Additionally, the degree of nonlinearity (DNL) at these offshore stations exceeded 4 when PGA reached 0.2–0.3 m/s2, a threshold significantly lower than the previously reported range of 0.5–1.0 m/s2. Furthermore, we observed systematic variations in nonlinear behaviors between flat and steep offshore stations, particularly with peak frequencies shifting towards lower and higher frequencies, respectively. These new findings may be mainly attributed to the intricate interaction of topography and marine sediments. Finally, simulations of two subduction earthquakes (MW6.2 and 5.9) using the stochastic finite-fault simulation method (SFFSM) showed good agreement with observations at frequencies above 0.1 Hz. Notably, nonlinear AFs outperformed linear ones across a wide PGA range of 0.2–1.2 m/s2, highlighting the significance of nonlinear site behaviors in characterizing offshore ground-motions. This finding reinforces the potential of the simulation framework (integrating GIT and SFFSM) for effectively and accurately simulating offshore ground-motion.
{"title":"Seismic response characteristics of offshore sites in the Sagami Bay, Japan—Part II: Nonlinear behaviors and stochastic simulation of subduction zone earthquakes","authors":"Lei Fu , Su Chen , Zhinan Xie , Suyang Wang , Junlei Chen , Xiaojun Li","doi":"10.1016/j.soildyn.2024.109081","DOIUrl":"10.1016/j.soildyn.2024.109081","url":null,"abstract":"<div><div>Despite their crucial importance for marine engineering, the nonlinear seismic response characteristics of offshore sites remain poorly understood. Consequently, simulating ground-motion at offshore sites poses a significant challenge. To address this, this study begins with a dataset comprising stress drops of 70 earthquakes, region-specific quality factors, and linear site amplification factors (AFs) of six offshore stations in Sagami Bay, Japan, obtained using the generalized inversion technique (GIT). Then, by incorporating additional offshore accelerograms with focal depths up to 333 km and peak ground accelerations (PGAs) ranging from 0.2 to 4.2 m/s<sup>2</sup>, we delve deeper into the effects of nonlinear site behaviors on the high-frequency attenuation parameter (<em>κ</em><sub>0</sub>) and AFs, respectively. A counterintuitive decrease in <em>κ</em><sub>0</sub> was observed as the peak ground acceleration (PGA) reached 0.5–0.8 m/s<sup>2</sup>, echoing similar observations from previous studies on KiK-net stations. Our results indicate that the high-frequency attenuation characteristics of offshore sites vary under strong motions, potentially attributable to the nonlinear evolution of the frequency-independent quality factor and S-wave velocity within near-surface sediments. Additionally, the degree of nonlinearity (DNL) at these offshore stations exceeded 4 when PGA reached 0.2–0.3 m/s<sup>2</sup>, a threshold significantly lower than the previously reported range of 0.5–1.0 m/s<sup>2</sup>. Furthermore, we observed systematic variations in nonlinear behaviors between flat and steep offshore stations, particularly with peak frequencies shifting towards lower and higher frequencies, respectively. These new findings may be mainly attributed to the intricate interaction of topography and marine sediments. Finally, simulations of two subduction earthquakes (<em>M</em><sub>W</sub>6.2 and 5.9) using the stochastic finite-fault simulation method (SFFSM) showed good agreement with observations at frequencies above 0.1 Hz. Notably, nonlinear AFs outperformed linear ones across a wide PGA range of 0.2–1.2 m/s<sup>2</sup>, highlighting the significance of nonlinear site behaviors in characterizing offshore ground-motions. This finding reinforces the potential of the simulation framework (integrating GIT and SFFSM) for effectively and accurately simulating offshore ground-motion.</div></div>","PeriodicalId":49502,"journal":{"name":"Soil Dynamics and Earthquake Engineering","volume":"188 ","pages":"Article 109081"},"PeriodicalIF":4.2,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659713","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 : 2024-11-12DOI: 10.1016/j.soildyn.2024.109069
Yrene Santiago, Christian Ledezma, Juan Carlos Tiznado
Infrastructure failure due to soil liquefaction has been repeatedly observed in past megathrust earthquakes, causing significant material and structural functionality losses. In most seismic regions, soil liquefaction potential is assessed using updated versions of the cyclic-stress-based simplified procedure initially proposed by Seed and Idriss in 1971. However, the application of these procedures to large-magnitude (Mw > 7.5) subduction earthquakes has shown discrepancies between forward predictions and field observations, particularly regarding liquefaction triggering and manifestation. This paper proposes an alternative model to assess soil liquefaction due to large-magnitude subduction earthquakes based on excess pore water pressure ratios and shear deformations. The triggering criteria are based on the peak values of excess pore pressure ratio and shear strain anticipated within the critical, potentially liquefiable soil layer. The model considers liquefiable layer thickness and relative density, along with input motion's Cumulative Absolute Velocity (CAV), as the main predictors of soil liquefaction. To this end, a numerical model was first developed and validated against results from a dynamic centrifuge test simulating free-field conditions. The calibrated numerical model was then used to perform a numerical parametric study to identify the trends and key predictors of liquefaction in layered soil deposits subjected to large-magnitude subduction earthquakes. Finally, a simplified probabilistic procedure, validated against available case histories, was developed to estimate the probabilities of full, marginal, and no liquefaction occurrence within each critical layer.
{"title":"Assessing soil liquefaction due to large-magnitude subduction earthquakes","authors":"Yrene Santiago, Christian Ledezma, Juan Carlos Tiznado","doi":"10.1016/j.soildyn.2024.109069","DOIUrl":"10.1016/j.soildyn.2024.109069","url":null,"abstract":"<div><div>Infrastructure failure due to soil liquefaction has been repeatedly observed in past megathrust earthquakes, causing significant material and structural functionality losses. In most seismic regions, soil liquefaction potential is assessed using updated versions of the cyclic-stress-based simplified procedure initially proposed by Seed and Idriss in 1971. However, the application of these procedures to large-magnitude (M<sub>w</sub> > 7.5) subduction earthquakes has shown discrepancies between forward predictions and field observations, particularly regarding liquefaction triggering and manifestation. This paper proposes an alternative model to assess soil liquefaction due to large-magnitude subduction earthquakes based on excess pore water pressure ratios and shear deformations. The triggering criteria are based on the peak values of excess pore pressure ratio and shear strain anticipated within the critical, potentially liquefiable soil layer. The model considers liquefiable layer thickness and relative density, along with input motion's Cumulative Absolute Velocity (CAV), as the main predictors of soil liquefaction. To this end, a numerical model was first developed and validated against results from a dynamic centrifuge test simulating free-field conditions. The calibrated numerical model was then used to perform a numerical parametric study to identify the trends and key predictors of liquefaction in layered soil deposits subjected to large-magnitude subduction earthquakes. Finally, a simplified probabilistic procedure, validated against available case histories, was developed to estimate the probabilities of full, marginal, and no liquefaction occurrence within each critical layer.</div></div>","PeriodicalId":49502,"journal":{"name":"Soil Dynamics and Earthquake Engineering","volume":"188 ","pages":"Article 109069"},"PeriodicalIF":4.2,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659711","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 : 2024-11-12DOI: 10.1016/j.soildyn.2024.109076
Boyuan Cai , Xiaoguang Cai , Sihan Li , Xin Huang , Yan Zhang , Chengzhi Xiao
Deciding on the inclusion of tiers and determining the optimal number of tiers are critical considerations in the design of reinforced soil retaining walls (RSRWs). In this study, the mechanical properties of RSRWs under seismic loading are discussed in depth, with special attention paid to the influence of tiered configuration effects on the seismic performance of RSRWs. The response characteristics of these structures under seismic loading were comparatively analyzed by conducting shaking table tests of single-tiered, two-tiered, and three-tiered modular geogrid RSRWs. The results show that localized modular misalignment mainly occurs at the top of the retaining walls of all tiers, and reasonable tiered design can enhance the stability, but too many tiers may instead reduce the structural stability. The tiered reinforced soil retaining walls (TRSRWs) exhibit higher natural frequencies and damping ratios, which increase with more tiers, and the natural frequencies and damping ratios of the upper-tiered walls are always higher than those of the lower-tiered walls. The acceleration amplification effect is more significant in the upper part of the retaining wall structure, and the tiered design can reduce the acceleration amplification effect to a certain extent, but the increase in the number of tiers does not have much effect on this. The horizontal displacement of the TRSRWs shows the distribution of “upper large and lower small”, and the two-tiered retaining wall effectively reduces the horizontal displacement of the wall facing, whereas the three-tiered retaining wall does not have a significant improvement effect. The tiered design significantly optimizes the settlement of the retaining walls, and the number of tiers has little effect on the settlement improvement. The seismic active soil pressure increased with the peak ground acceleration and loading frequency, and the tiered design changed its distribution, and the increase in the number of tiers helped to further reduce the soil pressure. The increment of reinforcement strain in TRSRWs was lower than that in single-tiered retaining walls, and the tiered design effectively reduced the reinforcement stress, but the number of tiers had a limited effect on the improvement of this effect. The upper part of the wall in the un-tiered design is prone to overall tilt and horizontal expansion, and the deformation of the upper-tiered walls of the TRSRWs is all in a composite deformation mode, while the lowest-tiered walls are in a single deformation mode. The tiered design has a positive effect in limiting the development of potential failure surfaces in the substructure, resulting in improved stability of the substructure. The results of the study can provide a reference for the design selection of RSRWs.
{"title":"Experimental study of shaking table for reinforced soil retaining walls: Analysis of tiered configuration effects","authors":"Boyuan Cai , Xiaoguang Cai , Sihan Li , Xin Huang , Yan Zhang , Chengzhi Xiao","doi":"10.1016/j.soildyn.2024.109076","DOIUrl":"10.1016/j.soildyn.2024.109076","url":null,"abstract":"<div><div>Deciding on the inclusion of tiers and determining the optimal number of tiers are critical considerations in the design of reinforced soil retaining walls (RSRWs). In this study, the mechanical properties of RSRWs under seismic loading are discussed in depth, with special attention paid to the influence of tiered configuration effects on the seismic performance of RSRWs. The response characteristics of these structures under seismic loading were comparatively analyzed by conducting shaking table tests of single-tiered, two-tiered, and three-tiered modular geogrid RSRWs. The results show that localized modular misalignment mainly occurs at the top of the retaining walls of all tiers, and reasonable tiered design can enhance the stability, but too many tiers may instead reduce the structural stability. The tiered reinforced soil retaining walls (TRSRWs) exhibit higher natural frequencies and damping ratios, which increase with more tiers, and the natural frequencies and damping ratios of the upper-tiered walls are always higher than those of the lower-tiered walls. The acceleration amplification effect is more significant in the upper part of the retaining wall structure, and the tiered design can reduce the acceleration amplification effect to a certain extent, but the increase in the number of tiers does not have much effect on this. The horizontal displacement of the TRSRWs shows the distribution of “upper large and lower small”, and the two-tiered retaining wall effectively reduces the horizontal displacement of the wall facing, whereas the three-tiered retaining wall does not have a significant improvement effect. The tiered design significantly optimizes the settlement of the retaining walls, and the number of tiers has little effect on the settlement improvement. The seismic active soil pressure increased with the peak ground acceleration and loading frequency, and the tiered design changed its distribution, and the increase in the number of tiers helped to further reduce the soil pressure. The increment of reinforcement strain in TRSRWs was lower than that in single-tiered retaining walls, and the tiered design effectively reduced the reinforcement stress, but the number of tiers had a limited effect on the improvement of this effect. The upper part of the wall in the un-tiered design is prone to overall tilt and horizontal expansion, and the deformation of the upper-tiered walls of the TRSRWs is all in a composite deformation mode, while the lowest-tiered walls are in a single deformation mode. The tiered design has a positive effect in limiting the development of potential failure surfaces in the substructure, resulting in improved stability of the substructure. The results of the study can provide a reference for the design selection of RSRWs.</div></div>","PeriodicalId":49502,"journal":{"name":"Soil Dynamics and Earthquake Engineering","volume":"188 ","pages":"Article 109076"},"PeriodicalIF":4.2,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659650","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 : 2024-11-11DOI: 10.1016/j.soildyn.2024.109072
Martin Labuta , Ivo Oprsal , Daniel-Aaron Landa , Jan Burjánek
We introduce non-invasive seismic methods for identifying and characterizing maar sedimentary infills. We conducted a dense ambient vibration survey and employed state-of-the-art 3D resonance analysis techniques to map the lateral extent and depths of the sedimentary layers, a challenge with traditional geophysical methods due to unfavorable aspect ratios (depth > lateral dimension). The ambient vibrations of maars are predominantly driven by normal mode motions due to 3D resonance of crater infills. Dense station coverage enabled detailed images of the normal mode shapes revealing infill symmetries. The resonance results in extreme ground motion amplification, with factors reaching up to 30 on the vertical component, challenging conventional beliefs about site effects and methodologies based on widely used horizontal-to-vertical spectral ratios. These results are supported by numerical simulations of the maar's seismic response. The observed response is so specific that it can be used to identify partly eroded maar structures in the field.
我们介绍了用于识别和描述玛珥沉积填充物的非侵入式地震方法。我们进行了密集的环境振动勘测，并采用了最先进的三维共振分析技术来绘制沉积层的横向范围和深度，由于不利的纵横比（深度>；横向维度），这是传统地球物理方法所面临的挑战。由于火山口填充物的三维共振，火山口的环境振动主要由正常模式运动驱动。通过密集的站点覆盖，可以获得法向模态形状的详细图像，从而揭示填充物的对称性。共振导致了地面运动的极度放大，垂直分量的放大系数高达 30，这对传统的场地效应观念和基于广泛使用的水平与垂直频谱比的方法提出了挑战。这些结果得到了玛珥地震响应数值模拟的支持。观测到的反应非常具体，可用来在现场识别部分被侵蚀的 maar 结构。
{"title":"Ambient vibrations of a deep maar resonator","authors":"Martin Labuta , Ivo Oprsal , Daniel-Aaron Landa , Jan Burjánek","doi":"10.1016/j.soildyn.2024.109072","DOIUrl":"10.1016/j.soildyn.2024.109072","url":null,"abstract":"<div><div>We introduce non-invasive seismic methods for identifying and characterizing maar sedimentary infills. We conducted a dense ambient vibration survey and employed state-of-the-art 3D resonance analysis techniques to map the lateral extent and depths of the sedimentary layers, a challenge with traditional geophysical methods due to unfavorable aspect ratios (depth > lateral dimension). The ambient vibrations of maars are predominantly driven by normal mode motions due to 3D resonance of crater infills. Dense station coverage enabled detailed images of the normal mode shapes revealing infill symmetries. The resonance results in extreme ground motion amplification, with factors reaching up to 30 on the vertical component, challenging conventional beliefs about site effects and methodologies based on widely used horizontal-to-vertical spectral ratios. These results are supported by numerical simulations of the maar's seismic response. The observed response is so specific that it can be used to identify partly eroded maar structures in the field.</div></div>","PeriodicalId":49502,"journal":{"name":"Soil Dynamics and Earthquake Engineering","volume":"188 ","pages":"Article 109072"},"PeriodicalIF":4.2,"publicationDate":"2024-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659710","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 : 2024-11-11DOI: 10.1016/j.soildyn.2024.109067
Zexu Fan , Yong Yuan , Roberto Cudmani , Jinghua Zhang , Mingqing Sun , Stylianos Chrisopoulos
Earthquake-induced liquefaction poses grave safety risks to the underground structures. In this study, 1-g shaking table tests were conducted to investigate the uplift behaviors and soil-structure interaction (SSI) of a two-part tunnel located in liquefiable soils, with special attention paid to the influence of structural surface roughness. Two parallel tests, including a free-field test and a soil-tunnel test, were carried out to investigate the field responses and the effect of SSI during liquefaction induced by various input motions. The test results indicate that the ground partially liquefied during the first shaking event, and then experienced full liquefaction in the subsequent events with higher loading amplitude and longer loading duration. The excess pore pressure and horizontal acceleration responses around the tunnel were significantly altered due to the presence of the tunnel, which also led to different patterns of acceleration amplification and strain development in its vicinity. While structural surface roughness influenced the aforementioned responses to some extent, it played a more dominant role in the uplift behavior of the tunnel. The segment with lower surface roughness experienced significantly greater uplift compared to the rougher counterpart. Furthermore, it was found that the structural uplift behavior can be divided into distinct stages that feature different patterns of pore pressure development, and such behavior was notably different under varied loading conditions. The findings in this research emphasize the importance of incorporating the considerations of surface roughness in future numerical or experimental studies so that the structural uplift can be better captured.
{"title":"Experimental study on the seismic behavior of tunnels with distinct surface roughness in liquefiable soils","authors":"Zexu Fan , Yong Yuan , Roberto Cudmani , Jinghua Zhang , Mingqing Sun , Stylianos Chrisopoulos","doi":"10.1016/j.soildyn.2024.109067","DOIUrl":"10.1016/j.soildyn.2024.109067","url":null,"abstract":"<div><div>Earthquake-induced liquefaction poses grave safety risks to the underground structures. In this study, 1-g shaking table tests were conducted to investigate the uplift behaviors and soil-structure interaction (SSI) of a two-part tunnel located in liquefiable soils, with special attention paid to the influence of structural surface roughness. Two parallel tests, including a free-field test and a soil-tunnel test, were carried out to investigate the field responses and the effect of SSI during liquefaction induced by various input motions. The test results indicate that the ground partially liquefied during the first shaking event, and then experienced full liquefaction in the subsequent events with higher loading amplitude and longer loading duration. The excess pore pressure and horizontal acceleration responses around the tunnel were significantly altered due to the presence of the tunnel, which also led to different patterns of acceleration amplification and strain development in its vicinity. While structural surface roughness influenced the aforementioned responses to some extent, it played a more dominant role in the uplift behavior of the tunnel. The segment with lower surface roughness experienced significantly greater uplift compared to the rougher counterpart. Furthermore, it was found that the structural uplift behavior can be divided into distinct stages that feature different patterns of pore pressure development, and such behavior was notably different under varied loading conditions. The findings in this research emphasize the importance of incorporating the considerations of surface roughness in future numerical or experimental studies so that the structural uplift can be better captured.</div></div>","PeriodicalId":49502,"journal":{"name":"Soil Dynamics and Earthquake Engineering","volume":"188 ","pages":"Article 109067"},"PeriodicalIF":4.2,"publicationDate":"2024-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659708","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 : 2024-11-11DOI: 10.1016/j.soildyn.2024.109079
Qiang Lian , Libo Chen , Xinzhi Dang , Weidong Zhuo , Changchun Li
Earthquake-induced debris flow landslides pose a serious threat to bridge structures. However, current research on the dynamic response and damage mechanisms of bridges due to debris flow landslides is still insufficient; the fragility analysis of bridges under the combined effects of earthquakes and related geological hazards needs further improvement. In this paper, a bridge dynamic response simulation method is proposed for the coupled effects of transverse earthquakes and debris flow landslides. The method first establishes an integrated model of the mountain and bridge piers, using the discrete element method to calculate the dynamic impact of the landslide on the piers. Subsequently, a nonlinear dynamic model of the bridge is established using the finite element method. By inputting the time histories of transverse seismic motion and landslide impact, the coupled effects of transverse earthquakes and landslides are analyzed. The paper analyzes the influence of sliding distance, landslide length, and slope gradient on the dynamic response and fragility of bridges through case studies. Research reveals that the shear capacity of the pier under the coupled effects of earthquakes and landslides should be considered. The combined effects also increase the displacement response of the piers, with the maximum pier top drift ratio of the case bridge increasing by 334 % at a 35° slope compared to the earthquake-only condition. Under the coupled effects of earthquakes and landslides, the piers will experience significant residual deformation in the direction of the landslide. Increases in sliding distance, landslide length, and slope gradient all increase the fragility of bridges under various damage states, with the complete damage probability of the case bridge rising from 5 % under earthquake-only conditions to 47 % at a 35° slope. The slope gradient has the greatest sensitivity to the fragility of bridges, followed by the sliding distance, and finally the landslide length.
{"title":"Dynamic response and fragility of mountain bridges under the coupled effects of transverse earthquakes and landslides","authors":"Qiang Lian , Libo Chen , Xinzhi Dang , Weidong Zhuo , Changchun Li","doi":"10.1016/j.soildyn.2024.109079","DOIUrl":"10.1016/j.soildyn.2024.109079","url":null,"abstract":"<div><div>Earthquake-induced debris flow landslides pose a serious threat to bridge structures. However, current research on the dynamic response and damage mechanisms of bridges due to debris flow landslides is still insufficient; the fragility analysis of bridges under the combined effects of earthquakes and related geological hazards needs further improvement. In this paper, a bridge dynamic response simulation method is proposed for the coupled effects of transverse earthquakes and debris flow landslides. The method first establishes an integrated model of the mountain and bridge piers, using the discrete element method to calculate the dynamic impact of the landslide on the piers. Subsequently, a nonlinear dynamic model of the bridge is established using the finite element method. By inputting the time histories of transverse seismic motion and landslide impact, the coupled effects of transverse earthquakes and landslides are analyzed. The paper analyzes the influence of sliding distance, landslide length, and slope gradient on the dynamic response and fragility of bridges through case studies. Research reveals that the shear capacity of the pier under the coupled effects of earthquakes and landslides should be considered. The combined effects also increase the displacement response of the piers, with the maximum pier top drift ratio of the case bridge increasing by 334 % at a 35° slope compared to the earthquake-only condition. Under the coupled effects of earthquakes and landslides, the piers will experience significant residual deformation in the direction of the landslide. Increases in sliding distance, landslide length, and slope gradient all increase the fragility of bridges under various damage states, with the complete damage probability of the case bridge rising from 5 % under earthquake-only conditions to 47 % at a 35° slope. The slope gradient has the greatest sensitivity to the fragility of bridges, followed by the sliding distance, and finally the landslide length.</div></div>","PeriodicalId":49502,"journal":{"name":"Soil Dynamics and Earthquake Engineering","volume":"188 ","pages":"Article 109079"},"PeriodicalIF":4.2,"publicationDate":"2024-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659709","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 : 2024-11-08DOI: 10.1016/j.soildyn.2024.109063
N. Ravi Kiran , Ravi S. Jakka , Yogendra Singh
Despite being seismically vulnerable, foundations on slopes continue to be designed using the bearing capacity equation meant for shallow foundations resting on flat ground. While some bridge design specifications specify reduction factors for the estimation of bearing capacity of shallow foundations on slopes, the loading condition assumed in arriving at these reduction factors is not consistent with the actual field conditions. The present study highlights the limitations of the current code-based approaches for the seismic design of shallow foundations resting on slopes. Triaxial (V-Hx-Hy) seismic capacity surfaces are developed by performing three-dimensional finite element limit analyses, using pseudo-static approach, on surface and embedded square footings resting on dry and homogeneous sandy slopes, using Optum G3. The relationship between the horizontal force and the moment acting on a foundation, governed by the effective height of the supported column, is considered in developing the capacity surfaces. The vertical load capacity of a foundation on a slope is significantly lower than that of a similar foundation on flat ground. Additionally, the difference in horizontal capacities in the down-slope and up-slope directions increases with the axial load level. Foundation embedment significantly enhances both vertical and horizontal load capacities. A foundation located at the minimum edge distance from the slope face has a much higher vertical load capacity than a surface foundation placed at the crest. Failure mechanisms governed by horizontal load result in lower foundation capacity compared to those governed by moment. The seismic coefficient in the down-slope direction negatively affects foundation capacity.
{"title":"Effective height based interaction surface approach for the seismic design of shallow foundations resting on homogeneous slopes","authors":"N. Ravi Kiran , Ravi S. Jakka , Yogendra Singh","doi":"10.1016/j.soildyn.2024.109063","DOIUrl":"10.1016/j.soildyn.2024.109063","url":null,"abstract":"<div><div>Despite being seismically vulnerable, foundations on slopes continue to be designed using the bearing capacity equation meant for shallow foundations resting on flat ground. While some bridge design specifications specify reduction factors for the estimation of bearing capacity of shallow foundations on slopes, the loading condition assumed in arriving at these reduction factors is not consistent with the actual field conditions. The present study highlights the limitations of the current code-based approaches for the seismic design of shallow foundations resting on slopes. Triaxial (<em>V-H</em><sub><em>x</em></sub><em>-H</em><sub><em>y</em></sub>) seismic capacity surfaces are developed by performing three-dimensional finite element limit analyses, using pseudo-static approach, on surface and embedded square footings resting on dry and homogeneous sandy slopes, using Optum G3. The relationship between the horizontal force and the moment acting on a foundation, governed by the effective height of the supported column, is considered in developing the capacity surfaces. The vertical load capacity of a foundation on a slope is significantly lower than that of a similar foundation on flat ground. Additionally, the difference in horizontal capacities in the down-slope and up-slope directions increases with the axial load level. Foundation embedment significantly enhances both vertical and horizontal load capacities. A foundation located at the minimum edge distance from the slope face has a much higher vertical load capacity than a surface foundation placed at the crest. Failure mechanisms governed by horizontal load result in lower foundation capacity compared to those governed by moment. The seismic coefficient in the down-slope direction negatively affects foundation capacity.</div></div>","PeriodicalId":49502,"journal":{"name":"Soil Dynamics and Earthquake Engineering","volume":"188 ","pages":"Article 109063"},"PeriodicalIF":4.2,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659699","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 : 2024-11-08DOI: 10.1016/j.soildyn.2024.109078
Jie Fan , Changwei Yang , Mao Yue , Jia Luo , Jing Lian , Peiyong Wei
Flexible barrier structures are commonly installed in mountainous regions to resist the impact effects of rock avalanches. Without reliable physical data, the study of rock landslide initiation and the impact mechanism of avalanche debris flow under seismic excitation remains poorly understood. In this study, a model of rock slope-flexible barrier system was developed to simulate seismic slope failure behavior and debris flow impact on flexible barriers. Seismic waves in shaking table tests were triaxially loaded to effectively simulate actual seismic responses. The results indicate that the response of the Acceleration Amplification Factor (AAF) is closely associated with seismic damage and deformation within the overlying rock layers and differential propagation of seismic energy on either side of the shear band triggers rockslide initiation. Furthermore, the progressive failure mode of modeled slopes under multiple seismic events is slip-compression cracking failure. Crushing spreading at the intersection of the cracking and slip surfaces is the source of the loose fractured rock mass. Finally, this paper examines the impact patterns and dynamic responses of large individual blocks and loose fractured deposits on flexible barriers. Large blocks cause localized strong acceleration in the steel wire nets, increasing the risk of local damage, whereas loose deposits tend to induce overall seismic deformation and instability of the supporting structure. The natural seismic damage mechanisms of the barrier structure are revealed. It is recommended that flexible barrier structures in earthquake-prone mountainous areas incorporate a reasonable footing design to ensure the columns can deflect out-of-plane in response to seismic activity.
{"title":"Dynamic response of rock landslides and avalanche debris flows impacting flexible barriers based on shaking table tests","authors":"Jie Fan , Changwei Yang , Mao Yue , Jia Luo , Jing Lian , Peiyong Wei","doi":"10.1016/j.soildyn.2024.109078","DOIUrl":"10.1016/j.soildyn.2024.109078","url":null,"abstract":"<div><div>Flexible barrier structures are commonly installed in mountainous regions to resist the impact effects of rock avalanches. Without reliable physical data, the study of rock landslide initiation and the impact mechanism of avalanche debris flow under seismic excitation remains poorly understood. In this study, a model of rock slope-flexible barrier system was developed to simulate seismic slope failure behavior and debris flow impact on flexible barriers. Seismic waves in shaking table tests were triaxially loaded to effectively simulate actual seismic responses. The results indicate that the response of the Acceleration Amplification Factor (AAF) is closely associated with seismic damage and deformation within the overlying rock layers and differential propagation of seismic energy on either side of the shear band triggers rockslide initiation. Furthermore, the progressive failure mode of modeled slopes under multiple seismic events is slip-compression cracking failure. Crushing spreading at the intersection of the cracking and slip surfaces is the source of the loose fractured rock mass. Finally, this paper examines the impact patterns and dynamic responses of large individual blocks and loose fractured deposits on flexible barriers. Large blocks cause localized strong acceleration in the steel wire nets, increasing the risk of local damage, whereas loose deposits tend to induce overall seismic deformation and instability of the supporting structure. The natural seismic damage mechanisms of the barrier structure are revealed. It is recommended that flexible barrier structures in earthquake-prone mountainous areas incorporate a reasonable footing design to ensure the columns can deflect out-of-plane in response to seismic activity.</div></div>","PeriodicalId":49502,"journal":{"name":"Soil Dynamics and Earthquake Engineering","volume":"188 ","pages":"Article 109078"},"PeriodicalIF":4.2,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659698","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}
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