Soft soils require particular consideration when designing civil engineering structures due to their high compressibility, low shear strength, and permeability. Using chemical additives and geopolymers to stabilize soft soils is a practical approach to improve their engineering properties. The objective of the study was to explore the use of conventional stabilizers alongside metakaolin-based geopolymers. This study also aimed to investigate the compaction characteristics, mechanical strength, shear behavior, and microstructure of stabilized soft soil. The compaction test was carried out using various amounts of cement (6%, 8%, and 10%) and metakaolin (3%, 5%, and 7%) based on the dry weight of the soil. Cement, lime, and geopolymer were added to the soft soil at 15% of the dry weight of the soil for triaxial shear tests. The compaction test results indicated that the stabilized soil exhibited the highest maximum dry density at 8% cement content. Adding metakaolin (MK) to the cement-modified soil decreased the maximum dry density, smoothed the compaction curve, and increased the optimum moisture content. The unconfined compressive strength (UCS) test revealed that cement-stabilized soil had the highest yield stress, while adding MK to the cement-modified soil reduced the yield stress after 7 days of curing. Compared to untreated soft soil, there was a significant increase in shear strength parameters for cement-, metakaolin-, and lime-stabilized soil. This study demonstrates that adding chemical additives and geopolymers can improve the soft soil’s compaction characteristics, mechanical strength, and shear strength parameters.
{"title":"Mechanical Strength and Microstructure of Soft Soil Stabilized with Cement, Lime, and Metakaolin-Based Geopolymer Stabilizers","authors":"Tadesse Abebe Wassie, Gökhan Demir","doi":"10.1155/2024/6613742","DOIUrl":"https://doi.org/10.1155/2024/6613742","url":null,"abstract":"Soft soils require particular consideration when designing civil engineering structures due to their high compressibility, low shear strength, and permeability. Using chemical additives and geopolymers to stabilize soft soils is a practical approach to improve their engineering properties. The objective of the study was to explore the use of conventional stabilizers alongside metakaolin-based geopolymers. This study also aimed to investigate the compaction characteristics, mechanical strength, shear behavior, and microstructure of stabilized soft soil. The compaction test was carried out using various amounts of cement (6%, 8%, and 10%) and metakaolin (3%, 5%, and 7%) based on the dry weight of the soil. Cement, lime, and geopolymer were added to the soft soil at 15% of the dry weight of the soil for triaxial shear tests. The compaction test results indicated that the stabilized soil exhibited the highest maximum dry density at 8% cement content. Adding metakaolin (MK) to the cement-modified soil decreased the maximum dry density, smoothed the compaction curve, and increased the optimum moisture content. The unconfined compressive strength (UCS) test revealed that cement-stabilized soil had the highest yield stress, while adding MK to the cement-modified soil reduced the yield stress after 7 days of curing. Compared to untreated soft soil, there was a significant increase in shear strength parameters for cement-, metakaolin-, and lime-stabilized soil. This study demonstrates that adding chemical additives and geopolymers can improve the soft soil’s compaction characteristics, mechanical strength, and shear strength parameters.","PeriodicalId":7242,"journal":{"name":"Advances in Civil Engineering","volume":"176 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139752023","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Researchers have recently discovered that eggshell contains a significant amount of calcium carbonate through the characteristics of both fresh and hardened concrete by partially substituting cement with eggshell powder (ESP) at room temperature. The objective of this experimental investigation was to examine the microstructural and durability characteristics of high-strength concrete exposed to elevated temperatures using ESP as partial cement replacement. The impact of elevated temperature intensity (200, 400, 600, and 800°C) for one hour of exposure on the specimens and natural air-cooling method was studied. Various ESP cement blending percentages (0%, 5%, 10%, and 15%) were examined through different microstructural and durability tests such as workability, fire resistance, scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy, and 3D optical surface profiler, air content tests, ultrasonic pulse velocity, weight loss, spalling and color changes, water absorption, and acid attack experimental tests. According to the findings, the amount of ESP exceed 5% replacement reduces the workability of fresh concrete mixtures. The best performance was reached by a mixture comprising 5%ESP specimens, with values of 63.41 and 64.07 MPa at ambient and 200°C, respectively. SEM results of 5%ESP at 200°C illustrate a decrease in the occurrence of pores and act as a bridge to form crystals between CH and C─S─H. The XRD result also indicates a high amount of jennite (C─S─H gel) was formed at 200°C due to the melting of ESP, which densifies the crystal of C─S─H. Regression analysis provided a more reliable expression for the relationship between the residual compressive strength and UPV with R2 values of 0.9833 and 0.9966 for control and 5%ESP mixes, respectively. As a result, it was determined that concrete with 5%ESP as a partial cement replacement performs better over time than control concrete and has the potential to be used in construction.
{"title":"Effect of Elevated Temperature on Microstructural and Durability Properties of High-Strength Concrete-Containing Eggshell","authors":"Samuel Sisay Asgedom, Bahiru Bewket Mitikie","doi":"10.1155/2024/1177939","DOIUrl":"https://doi.org/10.1155/2024/1177939","url":null,"abstract":"Researchers have recently discovered that eggshell contains a significant amount of calcium carbonate through the characteristics of both fresh and hardened concrete by partially substituting cement with eggshell powder (ESP) at room temperature. The objective of this experimental investigation was to examine the microstructural and durability characteristics of high-strength concrete exposed to elevated temperatures using ESP as partial cement replacement. The impact of elevated temperature intensity (200, 400, 600, and 800°C) for one hour of exposure on the specimens and natural air-cooling method was studied. Various ESP cement blending percentages (0%, 5%, 10%, and 15%) were examined through different microstructural and durability tests such as workability, fire resistance, scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy, and 3D optical surface profiler, air content tests, ultrasonic pulse velocity, weight loss, spalling and color changes, water absorption, and acid attack experimental tests. According to the findings, the amount of ESP exceed 5% replacement reduces the workability of fresh concrete mixtures. The best performance was reached by a mixture comprising 5%ESP specimens, with values of 63.41 and 64.07 MPa at ambient and 200°C, respectively. SEM results of 5%ESP at 200°C illustrate a decrease in the occurrence of pores and act as a bridge to form crystals between CH and C─S─H. The XRD result also indicates a high amount of jennite (C─S─H gel) was formed at 200°C due to the melting of ESP, which densifies the crystal of C─S─H. Regression analysis provided a more reliable expression for the relationship between the residual compressive strength and UPV with <i>R</i><sup>2</sup> values of 0.9833 and 0.9966 for control and 5%ESP mixes, respectively. As a result, it was determined that concrete with 5%ESP as a partial cement replacement performs better over time than control concrete and has the potential to be used in construction.","PeriodicalId":7242,"journal":{"name":"Advances in Civil Engineering","volume":"155 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139752147","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Tsion Amsalu Fode, Yusufu Abeid Chande Jande, Thomas Kivevele
Construction industries are rapidly growing, sacking high amounts of concrete which has a highly dense microstructure with excellent mechanical properties, more durable, and highly eco-friendly materials. Hence, many of the researchers are interested in solving this problem with replacing concrete by natural pozzolana (NP) which is a supplementary cementitious material mostly from volcanic sources having much active silica content that can improve the durability and mechanical properties of concrete. However, it is not well-known which common optimum replacement range can give the most desirable concrete properties. So, the present study sought to review the effects of replacing NP from volcanic sources on the durability, physical, mechanical, and microstructural properties of concrete, also, to identify the most common dose of a positive effect as a replacement in concrete. The review shows that many of NP used by different literature from different places satisfy ASTM replacement standard in concrete, especially, based on its chemical compositions. Also, the review observed that employing NP in concrete significantly improves concrete workability, lengthens setting time, and reduces bulk density, porosity, water absorption, and chloride ion migration by making denser concrete microstructure. In general, adding 5%–20% of NP in concrete significantly improves compressive strength, split tensile strength, and flexural strength. Specifically, most of the studies found 15% replacement of NP having volcanic sources can give optimum strength. Besides these, most of the studies indicated that the improvement of the strength was more visible at the concrete age of 7–28 days.
{"title":"Effect of Natural Pozzolana on Physical and Mechanical Properties of Concrete","authors":"Tsion Amsalu Fode, Yusufu Abeid Chande Jande, Thomas Kivevele","doi":"10.1155/2024/3356641","DOIUrl":"https://doi.org/10.1155/2024/3356641","url":null,"abstract":"Construction industries are rapidly growing, sacking high amounts of concrete which has a highly dense microstructure with excellent mechanical properties, more durable, and highly eco-friendly materials. Hence, many of the researchers are interested in solving this problem with replacing concrete by natural pozzolana (NP) which is a supplementary cementitious material mostly from volcanic sources having much active silica content that can improve the durability and mechanical properties of concrete. However, it is not well-known which common optimum replacement range can give the most desirable concrete properties. So, the present study sought to review the effects of replacing NP from volcanic sources on the durability, physical, mechanical, and microstructural properties of concrete, also, to identify the most common dose of a positive effect as a replacement in concrete. The review shows that many of NP used by different literature from different places satisfy ASTM replacement standard in concrete, especially, based on its chemical compositions. Also, the review observed that employing NP in concrete significantly improves concrete workability, lengthens setting time, and reduces bulk density, porosity, water absorption, and chloride ion migration by making denser concrete microstructure. In general, adding 5%–20% of NP in concrete significantly improves compressive strength, split tensile strength, and flexural strength. Specifically, most of the studies found 15% replacement of NP having volcanic sources can give optimum strength. Besides these, most of the studies indicated that the improvement of the strength was more visible at the concrete age of 7–28 days.","PeriodicalId":7242,"journal":{"name":"Advances in Civil Engineering","volume":"7 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139752021","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mounded storage tank is to cover the storage tank with compacted soil on the ground to avoid steam cloud explosion, ensuring the stability and safety of the storage tank. In view of the influence of large diameter and surface radian of the tank, slope stability of mounded storage tank under different compaction coefficients has become the focus of research. In this paper, a series of laboratory tests were carried out to obtain the physical and mechanical parameters of the soil samples collected from the overburden of one specific engineering project. On this basis, Plaxis2D finite element software was used to establish a numerical model of the horizontal tank with a diameter of 7.6 m and a length of 76 m and the mounded slope with a height of 16.25 m as the research object. The effects of different compaction coefficients, slope angles, and overburden thicknesses on the slope stability of the mounded storage tank are investigated. Results indicate that the slope stability coefficients increase with the increase of compaction coefficient but decrease with the increase of slope angle and overburden thickness. Under the condition of the compaction coefficient 0.75–0.95, slope angle 30°–60°, and overburden thickness 0.5–1.3 m, the sensitivity ranking on the slope stability of mounded storage tank is: compaction coefficient, slope angle, and overburden thickness. The analysis results can provide an important theoretical basis and technical support for the safety and stability evaluation of mounded horizontal tank project.
{"title":"Slope Stability Analysis of Mounded Storage Tank under Different Compaction Coefficients","authors":"Yunsheng Ma, Zizhuo Tao, Yu Zhang, Zhenxue Liu, Shengke Wei, Fenghao Qing","doi":"10.1155/2024/6682882","DOIUrl":"https://doi.org/10.1155/2024/6682882","url":null,"abstract":"Mounded storage tank is to cover the storage tank with compacted soil on the ground to avoid steam cloud explosion, ensuring the stability and safety of the storage tank. In view of the influence of large diameter and surface radian of the tank, slope stability of mounded storage tank under different compaction coefficients has become the focus of research. In this paper, a series of laboratory tests were carried out to obtain the physical and mechanical parameters of the soil samples collected from the overburden of one specific engineering project. On this basis, Plaxis2D finite element software was used to establish a numerical model of the horizontal tank with a diameter of 7.6 m and a length of 76 m and the mounded slope with a height of 16.25 m as the research object. The effects of different compaction coefficients, slope angles, and overburden thicknesses on the slope stability of the mounded storage tank are investigated. Results indicate that the slope stability coefficients increase with the increase of compaction coefficient but decrease with the increase of slope angle and overburden thickness. Under the condition of the compaction coefficient 0.75–0.95, slope angle 30°–60°, and overburden thickness 0.5–1.3 m, the sensitivity ranking on the slope stability of mounded storage tank is: compaction coefficient, slope angle, and overburden thickness. The analysis results can provide an important theoretical basis and technical support for the safety and stability evaluation of mounded horizontal tank project.","PeriodicalId":7242,"journal":{"name":"Advances in Civil Engineering","volume":"1 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139752272","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Investigating the correlation between acoustic emission (AE) parameters and damage mechanisms in rock mechanics can help understand rock damage evolution under loading and provide a theoretical basis for engineering support and safety detection. Therefore, this paper presents experimental works on the correlation between AE and failure mechanisms of rock mass under uniaxial compression stress, with the aim of capturing the damage evolution leading to a new damage constitutive model. The experimental results indicate that the uniaxial compression process of shale can be divided into four stages according to AE characteristics. AE signals are minimal during the crack compaction and elastic stages. The crack initiation strength σci, which is approximately 55% of the uniaxial compressive strength, is identified when the cumulative AE counts and damage factor begin to increase slowly. When axial stress reaches the damage strength σcd, which is approximately 80% of the uniaxial compressive strength, a significant number of AE signals are generated. AE phenomena can be observed during the unstable crack development and post-crack stages. Considering the initial damage to the rock, the damage factor D initially decreases and then increases with increasing cumulative ring-down counts rather than exhibiting a monotonic increase. The damage factor D is proportional to the cumulative AE counts N in the stage before rock failure.
研究声发射（AE）参数与岩石力学中破坏机制之间的相关性，有助于理解加载条件下岩石破坏的演变过程，并为工程支持和安全检测提供理论依据。因此，本文介绍了单轴压缩应力下岩体声发射与破坏机理相关性的实验工作，旨在捕捉破坏演化过程，从而建立新的破坏构成模型。实验结果表明，根据 AE 特性，页岩的单轴压缩过程可分为四个阶段。在裂纹压实和弹性阶段，AE 信号最小。当累积 AE 计数和损伤因子开始缓慢增加时，可确定裂纹起始强度 σci，该强度约为单轴压缩强度的 55%。当轴向应力达到损伤强度 σcd（约为单轴抗压强度的 80%）时，会产生大量的 AE 信号。在不稳定的裂缝发展阶段和裂缝后阶段都能观察到 AE 现象。考虑到岩石的初始损伤，损伤因子 D 最初会降低，然后随着累计降环次数的增加而升高，而不是呈现单调的增长。破坏系数 D 与岩石破坏前阶段的累计 AE 计数 N 成正比。
{"title":"Study on Acoustic Emission Characteristics and Damage Evolution Law of Shale under Uniaxial Compression","authors":"Wenjie Wu, Chee-Ming Chan, Yilei Gu, Xiaopeng Su","doi":"10.1155/2024/3076780","DOIUrl":"https://doi.org/10.1155/2024/3076780","url":null,"abstract":"Investigating the correlation between acoustic emission (AE) parameters and damage mechanisms in rock mechanics can help understand rock damage evolution under loading and provide a theoretical basis for engineering support and safety detection. Therefore, this paper presents experimental works on the correlation between AE and failure mechanisms of rock mass under uniaxial compression stress, with the aim of capturing the damage evolution leading to a new damage constitutive model. The experimental results indicate that the uniaxial compression process of shale can be divided into four stages according to AE characteristics. AE signals are minimal during the crack compaction and elastic stages. The crack initiation strength <i>σ</i><sub>ci</sub>, which is approximately 55% of the uniaxial compressive strength, is identified when the cumulative AE counts and damage factor begin to increase slowly. When axial stress reaches the damage strength <i>σ</i><sub>cd</sub>, which is approximately 80% of the uniaxial compressive strength, a significant number of AE signals are generated. AE phenomena can be observed during the unstable crack development and post-crack stages. Considering the initial damage to the rock, the damage factor <i>D</i> initially decreases and then increases with increasing cumulative ring-down counts rather than exhibiting a monotonic increase. The damage factor <i>D</i> is proportional to the cumulative AE counts <i>N</i> in the stage before rock failure.","PeriodicalId":7242,"journal":{"name":"Advances in Civil Engineering","volume":"98 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139752111","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ce Gao, Zhibin Li, Hazem Elzarka, Hongyan Yan, Peijin Li
For managers of road infrastructure, culvert deterioration is a major concern since culvert failures can cause serious risks to the traveling public. The efficiency of the cost- and labor-intensive culvert inspection and maintenance process can be improved by properly identifying the key impact factors on culvert condition deterioration. Although the use of machine learning (ML) techniques to predict culvert conditions has been proven to be a promising tool for enhancing culvert management and enabling proactive scheduling of maintenance tasks, the information provided by the developed ML models has been given little attention for further use and analysis. By utilizing the predictor importance results of an evaluated decision tree (DT) culvert condition prediction model and the Mann–Whitney U test, this study provided insights to the identification of the key variables influencing culvert deterioration. According to the findings, five impact factors, including culvert span, pH, age, rise, and cover height, often have significant impact on the condition ratings of culverts made of various materials. In addition, such a statistical test-assisted factor identification process offered a way of identifying and enhancing the input variable selection for predictive ML model development.
对于道路基础设施的管理者来说，涵洞老化是一个主要问题，因为涵洞故障可能会对公众出行造成严重威胁。通过正确识别涵洞状况恶化的关键影响因素，可以提高成本和人力密集型涵洞检查和维护流程的效率。尽管使用机器学习（ML）技术来预测涵洞状况已被证明是一种很有前途的工具，可用于加强涵洞管理并实现维护任务的主动调度，但已开发的 ML 模型所提供的信息却很少得到进一步使用和分析的重视。通过利用已评估的决策树（DT）涵洞状况预测模型的预测因子重要性结果和曼-惠特尼 U 检验，本研究为确定影响涵洞劣化的关键变量提供了见解。研究结果表明，涵洞跨度、pH 值、使用年限、升高和覆盖层高度这五个影响因素往往对不同材料制成的涵洞的状况评级有重大影响。此外，这种统计测试辅助的因素识别过程还为开发预测性 ML 模型提供了一种识别和改进输入变量选择的方法。
{"title":"Machine Learning and Statistical Test–Based Culvert Condition Impact Factor Analysis","authors":"Ce Gao, Zhibin Li, Hazem Elzarka, Hongyan Yan, Peijin Li","doi":"10.1155/2024/9574203","DOIUrl":"https://doi.org/10.1155/2024/9574203","url":null,"abstract":"For managers of road infrastructure, culvert deterioration is a major concern since culvert failures can cause serious risks to the traveling public. The efficiency of the cost- and labor-intensive culvert inspection and maintenance process can be improved by properly identifying the key impact factors on culvert condition deterioration. Although the use of machine learning (ML) techniques to predict culvert conditions has been proven to be a promising tool for enhancing culvert management and enabling proactive scheduling of maintenance tasks, the information provided by the developed ML models has been given little attention for further use and analysis. By utilizing the predictor importance results of an evaluated decision tree (DT) culvert condition prediction model and the Mann–Whitney <i>U</i> test, this study provided insights to the identification of the key variables influencing culvert deterioration. According to the findings, five impact factors, including culvert span, pH, age, rise, and cover height, often have significant impact on the condition ratings of culverts made of various materials. In addition, such a statistical test-assisted factor identification process offered a way of identifying and enhancing the input variable selection for predictive ML model development.","PeriodicalId":7242,"journal":{"name":"Advances in Civil Engineering","volume":"57 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139752109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Under the action of extreme wind load, the overhead transmission line will generate a wind deflection flashover phenomenon, which seriously affects the normal operation of the transmission system and causes significant losses. Y-type insulator string (hereinafter referred to as Y-string) is an optimized structural form to reduce the wind deflection flashover in windy areas, and the dynamic mechanical characteristics of Y-string under the action of pulsating wind is an important factor that influences the design of the overhead transmission line. The calculation method of pulsating wind load and the static calculation method of wind deflection displacement of Y-string are obtained through theoretical derivation. The mathematical software is used to simulate the time course of pulsating wind speed and convert it into the time course of wind load, establish the finite element model of insulator string, simulate and analyze the wind deflection process of Y-string under the action of pulsating wind by using the finite element method, and calculate the horizontal displacement of Y-string under the excitation of pulsating wind and make a comparative analysis with the results of the static calculations. The results show that the wind deflection displacement of the Y-string under pulsating wind is 1.12–1.28 times that under steady-state wind, which reveals the reason for the wind deflection flashover phenomenon and provides theoretical references for the design and improvement of overhead transmission lines.
在极端风荷载作用下，架空输电线路会产生风偏闪络现象，严重影响输电系统的正常运行，造成重大损失。Y型绝缘子串（以下简称Y串）是减少大风地区风偏闪络的优化结构形式，Y串在脉动风作用下的动态力学特性是影响架空输电线路设计的重要因素。通过理论推导得到了脉动风荷载的计算方法和 Y 型绳风挠度位移的静力计算方法。利用数学软件模拟脉动风速的时间过程并转换为风荷载的时间过程，建立绝缘子串的有限元模型，利用有限元法模拟分析 Y 型绳在脉动风作用下的风偏过程，计算 Y 型绳在脉动风激励下的水平位移，并与静力计算结果进行对比分析。结果表明，脉动风作用下 Y 型绳的风挠位移是稳态风作用下的 1.12-1.28 倍，揭示了风挠闪络现象产生的原因，为架空输电线路的设计和改进提供了理论参考。
{"title":"Study on the Wind Deviation Characteristics of Y-Type Insulator String under the Action of Strong Wind","authors":"Xianren Wang, Chuiwei Yang, Jiaqian Zhang, Junyu Zhou, Hangzhang Liang, Jing Jiang, Yonghui Cai, Mojia Huang, Zhiwen Lan","doi":"10.1155/2024/5542173","DOIUrl":"https://doi.org/10.1155/2024/5542173","url":null,"abstract":"Under the action of extreme wind load, the overhead transmission line will generate a wind deflection flashover phenomenon, which seriously affects the normal operation of the transmission system and causes significant losses. Y-type insulator string (hereinafter referred to as Y-string) is an optimized structural form to reduce the wind deflection flashover in windy areas, and the dynamic mechanical characteristics of Y-string under the action of pulsating wind is an important factor that influences the design of the overhead transmission line. The calculation method of pulsating wind load and the static calculation method of wind deflection displacement of Y-string are obtained through theoretical derivation. The mathematical software is used to simulate the time course of pulsating wind speed and convert it into the time course of wind load, establish the finite element model of insulator string, simulate and analyze the wind deflection process of Y-string under the action of pulsating wind by using the finite element method, and calculate the horizontal displacement of Y-string under the excitation of pulsating wind and make a comparative analysis with the results of the static calculations. The results show that the wind deflection displacement of the Y-string under pulsating wind is 1.12–1.28 times that under steady-state wind, which reveals the reason for the wind deflection flashover phenomenon and provides theoretical references for the design and improvement of overhead transmission lines.","PeriodicalId":7242,"journal":{"name":"Advances in Civil Engineering","volume":"5 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139752113","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yi Zhang, Fan Zhang, Qingbo Yi, Guanzhu Jiang, Juncheng Xie
Surcharge loading on slopes is a prevalent engineering practice that can precipitate landslides, posing significant risks to construction integrity and safety. This study elucidates the impact of surcharge loading on mixed soil–rock slopes and benchmarks their response against that of pure soil slopes under analogous loading conditions. Investigating damage manifestations, this research quantifies the distribution of plastic zones, the morphological alterations of slopes at characteristic stages, the dynamics of slip velocity at monitoring points, and the extent of landslide run-out. The material point method is adopted for its proficiency in simulating large deformation scenarios. Two-dimensional models of a representative soil–rock mixed slope and a pure soil slope are meticulously crafted using digital image processing techniques. The distinct damage profiles exhibited by the mixed and pure soil slopes are compared. The comparative assessment elucidates the distinct damage patterns of different slopes, enhancing the understanding of their behavior under variable surcharge intensities and contributing to the discourse on slope stability assessments.
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Mohamed H. Abu-Ali, Basuony El-Garhy, Ahmed Boraey, Wael S. Al-Rashed, Hassan Abdel-Daiem
A stiffened raft is considered one of the efficient foundation systems for lightweight structures resting on expansive soils. Most existing design methods of stiffened rafts require an analysis of the interaction between the raft and the distorted mound shape of the expansive soil. In most design methods, the distorted mound shape is represented in 2D by the edge distance and the maximum differential movement through a nonlinear equation. This study presents a rational method for estimating the climate-controlled soil parameters that are used for estimating the 3D distorted mound shape of the expansive soil from the routine geotechnical tests’ results. These parameters include the equilibrium soil suction, the amplitude of surface suction change, the diffusion coefficient of the soil, the suction compression index, and the active zone depth. The proposed method is explained through its application to calculate the climate-controlled parameters for expansive soils in different locations throughout Saudi Arabia. A parametric study is carried out using a suction diffusion and soil movements program called SUCH to investigate the effect of the climate-controlled soil parameters and raft dimensions on the shape of the distorted mound, maximum differential movement, and edge moisture variation distance. The results of the parametric study are used in a regression analysis to develop an equation for estimating the edge moisture variation distance, which is considered a major barrier to using existing design methods of stiffened rafts as a function of the climate-controlled soil parameters and the aspect ratio of the raft. The findings indicate that the aspect ratio of the raft and the climate-controlled soil parameters have a significant effect on the shape of the distorted mound, its maximum differential movement, and its edge moisture variation distance. Additionally, the proposed equation of the edge moisture variation distance predicts comparable values to that estimated by the program SUCH.
加劲筏被认为是在膨胀土上建造轻型结构的有效地基系统之一。加劲筏的现有设计方法大多需要分析筏与膨胀土的变形土墩之间的相互作用。在大多数设计方法中，扭曲的土墩形状是通过非线性方程用边缘距离和最大差动来表示的。本研究提出了一种估算气候控制土参数的合理方法，这些参数用于从常规土工试验结果中估算膨胀土的三维扭曲土堆形状。这些参数包括平衡土壤吸力、表面吸力变化幅度、土壤扩散系数、吸力压缩指数和活动区深度。通过应用该方法计算沙特阿拉伯不同地区膨胀性土壤的气候控制参数，对所提出的方法进行了解释。使用名为 SUCH 的吸力扩散和土壤运动程序进行了参数研究，以调查气候控制土壤参数和筏尺寸对变形土丘形状、最大差动和边缘湿度变化距离的影响。参数研究的结果被用于回归分析，以建立一个估算边缘湿度变化距离的方程，而边缘湿度变化距离被认为是使用现有加劲筏设计方法的主要障碍，是气候控制土壤参数和筏的长宽比的函数。研究结果表明，筏的长宽比和气候控制土壤参数对变形土丘的形状、最大位移差和边缘湿度变化距离有显著影响。此外，所提出的边缘湿度变化距离方程预测值与 SUCH 程序估计值相当。
{"title":"Estimating the Climate-Controlled Soil Parameters and the Distorted Mound Shape for Analysis of Stiffened Rafts on Expansive Soils","authors":"Mohamed H. Abu-Ali, Basuony El-Garhy, Ahmed Boraey, Wael S. Al-Rashed, Hassan Abdel-Daiem","doi":"10.1155/2024/5599356","DOIUrl":"https://doi.org/10.1155/2024/5599356","url":null,"abstract":"A stiffened raft is considered one of the efficient foundation systems for lightweight structures resting on expansive soils. Most existing design methods of stiffened rafts require an analysis of the interaction between the raft and the distorted mound shape of the expansive soil. In most design methods, the distorted mound shape is represented in 2D by the edge distance and the maximum differential movement through a nonlinear equation. This study presents a rational method for estimating the climate-controlled soil parameters that are used for estimating the 3D distorted mound shape of the expansive soil from the routine geotechnical tests’ results. These parameters include the equilibrium soil suction, the amplitude of surface suction change, the diffusion coefficient of the soil, the suction compression index, and the active zone depth. The proposed method is explained through its application to calculate the climate-controlled parameters for expansive soils in different locations throughout Saudi Arabia. A parametric study is carried out using a suction diffusion and soil movements program called SUCH to investigate the effect of the climate-controlled soil parameters and raft dimensions on the shape of the distorted mound, maximum differential movement, and edge moisture variation distance. The results of the parametric study are used in a regression analysis to develop an equation for estimating the edge moisture variation distance, which is considered a major barrier to using existing design methods of stiffened rafts as a function of the climate-controlled soil parameters and the aspect ratio of the raft. The findings indicate that the aspect ratio of the raft and the climate-controlled soil parameters have a significant effect on the shape of the distorted mound, its maximum differential movement, and its edge moisture variation distance. Additionally, the proposed equation of the edge moisture variation distance predicts comparable values to that estimated by the program SUCH.","PeriodicalId":7242,"journal":{"name":"Advances in Civil Engineering","volume":"24 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139752110","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The present study investigates the dynamic properties of granite samples with varying degrees of defects through triaxial cyclic loading experiments conducted under different conditions, including varied confining pressures, loading frequencies, dynamic stress amplitudes, and number of cycles, and the dynamic response model of granite samples influenced by the confining pressure and frequency are constructed. The results show that the dynamic elastic modulus of granite increases, but its dynamic damping ratio decreases as the confining pressure increases. The dynamic elastic modulus and dynamic damping ratio of the granite increase as increasing frequency. The dynamic elastic modulus of granite increases with the increasing dynamic stress amplitude while its dynamic damping ratio decreases. The dynamic elastic modulus and dynamic damping ratio of granite decreases with an increasing number of cycles. The modified Duncan–Chang model can well describe the dynamical behavior of granite influenced by the confining pressure and frequency. The correlation coefficients of the modified model reached 0.98. It is worth saying that the correlation coefficient of the model is low at 20 Hz frequency. It indicates that frequency has a strong effect on the dynamic response of granite compared with the confining pressure. These data and models will be applied to the next step of detection and prediction of the tunnel rock stress state.
{"title":"Dynamic Properties and Dynamic Response Model of Jointed Granites by Cyclic Loading","authors":"Xiaobin Ding, Junxing Zhao, Yaojun Dong","doi":"10.1155/2024/7258680","DOIUrl":"https://doi.org/10.1155/2024/7258680","url":null,"abstract":"The present study investigates the dynamic properties of granite samples with varying degrees of defects through triaxial cyclic loading experiments conducted under different conditions, including varied confining pressures, loading frequencies, dynamic stress amplitudes, and number of cycles, and the dynamic response model of granite samples influenced by the confining pressure and frequency are constructed. The results show that the dynamic elastic modulus of granite increases, but its dynamic damping ratio decreases as the confining pressure increases. The dynamic elastic modulus and dynamic damping ratio of the granite increase as increasing frequency. The dynamic elastic modulus of granite increases with the increasing dynamic stress amplitude while its dynamic damping ratio decreases. The dynamic elastic modulus and dynamic damping ratio of granite decreases with an increasing number of cycles. The modified Duncan–Chang model can well describe the dynamical behavior of granite influenced by the confining pressure and frequency. The correlation coefficients of the modified model reached 0.98. It is worth saying that the correlation coefficient of the model is low at 20 Hz frequency. It indicates that frequency has a strong effect on the dynamic response of granite compared with the confining pressure. These data and models will be applied to the next step of detection and prediction of the tunnel rock stress state.","PeriodicalId":7242,"journal":{"name":"Advances in Civil Engineering","volume":"5 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139752149","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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