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Discussion of “Systematic literature review and mapping of the prediction of pile capacities” 关于 "系统文献综述和桩基承载力预测绘图 "的讨论
IF 0.5 Q4 ENGINEERING, GEOLOGICAL Pub Date : 2024-01-09 DOI: 10.28927/sr.2024.011123
Katia Bicalho, Reno Castello, Nelson Aoki
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引用次数: 0
Primary consolidation settlement due to ramp loading: Terzaghi (1943) method revisited 坡道荷载引起的原生固结沉降:Terzaghi (1943) 方法再探讨
IF 0.5 Q4 ENGINEERING, GEOLOGICAL Pub Date : 2024-01-09 DOI: 10.28927/sr.2024.003522
Vitor Albuquerque, Celso Romanel, Raphael Carneiro
Terzaghi (1943) developed an empirical method for primary consolidation due to a load applied at constant rate (ramp load) until the end of construction at time tc. The method considers that the settlement at a time t during construction, can be evaluated admitting the load applied instantaneously at time t/2. In this research, two alternative modifications are proposed for this Terzaghi’s empirical recommendation. The first one is based on a variable fraction of time t and the second modification keeps Terzaghi’s suggestion (t/2) but makes reductions in the average degree of consolidation Uv. Computed results for different construction time factors Tv were compared to Olson (1977) analytical solution. The first approach yielded a maximum difference of approximately 2.40% while the second alternative gave results that are practically the same as those calculated by Olson’s solution. The validity of these new approaches was also proven by reproducing odometer test results with good agreement.
Terzaghi(1943 年)开发了一种经验方法,用于计算在施工结束 tc 时以恒定速率施加荷载(斜坡荷载)引起的一次固结。该方法认为,施工过程中某一时刻 t 的沉降量可通过在时刻 t/2 时瞬时施加的荷载进行评估。在这项研究中,对 Terzaghi 的经验建议提出了两种可供选择的修改方案。第一种修改基于时间 t 的可变分量,第二种修改保留了特尔扎吉的建议(t/2),但降低了平均固结度 Uv。不同施工时间系数 Tv 的计算结果与奥尔森(1977 年)的分析方案进行了比较。第一种方法得出的最大差异约为 2.40%,而第二种方法得出的结果实际上与奥尔森解决方案计算出的结果相同。这些新方法的有效性还通过重现里程表测试结果得到了证明,两者吻合度很高。
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引用次数: 0
Behavior of clayey soil treated with nano magnesium oxide material 用纳米氧化镁材料处理粘性土壤的行为
IF 0.5 Q4 ENGINEERING, GEOLOGICAL Pub Date : 2023-12-14 DOI: 10.28927/sr.2024.014822
Zeena Al-Khazzaz, A. Aldaood, Muwafaq Awad, Mohammed Faris
Clayey soils are spread in many countries and require significant improvement. Recently, nanomaterial have been entered to the geotechnical research as a treatment material. Current study utilized magnesium oxide (MgO) as an additive to enhance swelling potential, compressibility characteristics, and index properties of clayey soil from Mosul city using different content of nano-MgO and under varies curing periods. The results showed that the free swell and swell pressure of the soil specimens have been reduced by 25%, and 19%, respectively for 0.25, and 0.75% content of nano material under 3 days of curing time at 25C. Results also showed that the compressibility characteristic represented by the compression index parameter has been reduced by 20.3% for 0.75% of nano-MgO material. Moreover, the soil plasticity index exhibited a maximum increase at 0.75% of nano content. Moreover, results showed that the pH value increased while the electrical conductivity (EC) decreased with the nano-MgO content. To evaluate the curing time effect, specimens were cured for varies curing time under curing temperature of 25 ºC. Then, the free swell, swell pressure, compression index, and Atterberg limits were measured. The results revealed that the free swell and swell pressure for both untreated and treated specimens were reduced during different periods of curing time. Furthermore, the compression index of treated soil was reduced by approximately half for curing time of 28 days. In sum, the swelling and consolidation reduction with curing brought significant improvement and promising results for the treated samples.
粘土在许多国家都很普遍,需要大力改善。最近,纳米材料作为一种处理材料进入了岩土工程研究领域。目前的研究利用氧化镁(MgO)作为添加剂,使用不同含量的纳米氧化镁,在不同的固化期,提高摩苏尔市粘性土壤的膨胀潜力、压缩特性和指数特性。结果表明,在 25C 温度下固化 3 天后,纳米材料的含量分别为 0.25% 和 0.75% 时,土壤试样的自由膨胀率和膨胀压力分别降低了 25% 和 19%。结果还显示,0.75% 的纳米氧化镁材料的压缩指数参数所代表的压缩特性降低了 20.3%。此外,纳米含量为 0.75% 时,土壤塑性指数的增幅最大。此外,结果表明,随着纳米氧化镁含量的增加,pH 值上升,而导电率(EC)下降。为了评估固化时间的影响,试样在 25 ºC 的固化温度下固化了不同的固化时间。然后测量了自由膨胀率、膨胀压力、压缩指数和阿特伯格极限。结果表明,在不同的固化时间段内,未处理和处理过的试样的自由膨胀率和膨胀压力都有所降低。此外,在 28 天的固化时间内,经处理土壤的压缩指数降低了约一半。总之,固化过程中膨胀和固结的减少为处理过的样本带来了显著的改善和可喜的结果。
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引用次数: 0
Numerical modeling of the behavior of a surface foundation located in the proximity of a slope 斜坡附近地表地基行为的数值模拟
IF 0.5 Q4 ENGINEERING, GEOLOGICAL Pub Date : 2023-12-14 DOI: 10.28927/sr.2024.008722
Bencheikh Messaouda, Aidoud Assia, Boukour Salima, Khaldi Nacera, Belabed Lazhar
Some foundations are placed on or near slopes or excavations, such as roads in mountainous areas, tower footings for power lines, and bridge abutments. The design of foundation under these conditions is complex and the studies available in this regard are limited and concerned mostly about the determination of the reduction of the bearing capacity coefficients associated with the presence of the slope except for Meyerhof who was a pioneer in developing a theory in 1957 to determine the ultimate bearing capacity of a foundation near a slope. However, the theory was independent of the slope inclination. In this study, we attempted to numerical modeling of the behavior of a shallow foundation using the finite element technique together with Plaxis 8.2 software to simulate the case of a foundation near a slope, in terms of examining the bearing capacity of the foundation for given slope features, soil characteristics and geometry conditions located near a slope subjected to a centered and / or eccentric load. The results obtained confirm that the position of the eccentricity of the load relative to the head of the slope has a significant effect on the bearing capacity. Indeed, it becomes larger when the eccentricity is located far from the crest of the slope. Thus, the bearing capacity of a footing subjected to a centered load (e/B = 0) is greater than that of the same footing subjected to an eccentric load (e/B = 0.1). It is noted that the results obtained from the present study are in good agreement with those of the literature.
有些地基位于或靠近斜坡或挖方,例如山区道路、电线塔基和桥墩。这些条件下的地基设计非常复杂,这方面的研究也很有限,而且主要涉及确定与斜坡存在相关的承载力系数的降低,只有 Meyerhof 在 1957 年率先提出了确定斜坡附近地基极限承载力的理论。不过,该理论与斜坡倾斜度无关。在本研究中,我们尝试使用有限元技术和 Plaxis 8.2 软件对浅层地基的行为进行数值建模,模拟斜坡附近地基的情况,即在给定的斜坡特征、土壤特性和几何条件下,位于承受中心荷载和/或偏心荷载的斜坡附近的地基的承载能力。结果证实,相对于坡顶的偏心荷载位置对承载能力有显著影响。事实上,当偏心距坡顶较远时,承载力会变大。因此,承受中心荷载(e/B = 0)的基脚的承载能力大于承受偏心荷载(e/B = 0.1)的基脚的承载能力。可以看出,本研究得出的结果与文献中的结果十分吻合。
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引用次数: 0
Analysis of sorption/desorption of cadmium and lead in the legal amazon soils 亚马逊法定土壤中镉和铅的吸附/解吸分析
IF 0.5 Q4 ENGINEERING, GEOLOGICAL Pub Date : 2023-12-14 DOI: 10.28927/sr.2024.014022
Nicoly Rocha, Claudio Mahler
Sorption and desorption tests were carried out for competitive and non-competitive systems with isotherms to verify the presence of Cd and Pb in soils. The soils investigated were: (i) with natural content of organic matter and (ii) with residual content of organic matter. Hydrated nitrate salts of Cd and Pb diluted in 0.01 M calcium nitrate solution in six concentrations were used for the Cd solutions and, for the solutions of Pb, five concentrations. For multielement solutions, mixtures of the simple Cd and Pb solutions in a 1:1 ratio were used. The results of the first stage tests (i) showed good adjustments of the experimental data to the isotherms of Langmuir, Freundlich and Linear, which did not occur for the tests in stage (ii). According to the tests (i), the organic matter was the soil attribute of dominant influence in the sorting mechanisms. The parameters Qo and Kd were adequate to evaluate the adsorption of the studied metals, especially Cd. In step (ii), there was a significant increase in metal retention, especially for element Pb in the samples of Haplic Cambisol (AM) and Red-Yellow Latosol1 (RO), justified by the combined action of (1) increasing the surface area of the mineral fraction, previously covered by organic matter; and (2) increase in soil pH. The Cd element was more bioavailable in relation to the Pb. This was confirmed by the high desorption values observed for Cd. The samples of Haplic Cambisol and Red-Yellow Latosol demonstrated greater capacity to retain Cd and Pb.
对具有等温线的竞争性和非竞争性系统进行了吸附和解吸测试,以验证土壤中是否存在镉和铅。调查的土壤包括(i) 含有天然有机物的土壤;(ii) 含有残留有机物的土壤。镉溶液使用了在 0.01 M 硝酸钙溶液中稀释的六种浓度的镉和铅水合硝酸盐,铅溶液使用了五种浓度的硝酸盐。对于多元素溶液,则使用 1:1 比例的简单镉和铅溶液的混合物。第一阶段测试(i)的结果表明,实验数据与 Langmuir、Freundlich 和 Linear 等温线相吻合。根据试验(i),有机质是对分选机制有主要影响的土壤特性。Qo 和 Kd 参数足以评估所研究金属(尤其是镉)的吸附情况。在步骤(ii)中,金属保留率显著增加,特别是在 Haplic Cambisol (AM) 和 Red-Yellow Latosol1 (RO) 样品中的铅元素,这是由于(1)增加了之前被有机物覆盖的矿物部分的表面积;(2)土壤 pH 值增加的综合作用。与铅相比,镉元素的生物利用率更高。镉的高解吸值证实了这一点。Haplic Cambisol 和 Red-Yellow Latosol 样本对镉和铅的保留能力更强。
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引用次数: 0
Comparative evaluation of constitutive models for stress-strain analysis of an iron ore tailings from the Quadrilátero Ferrífero, Minas Gerais, Brazil 对巴西米纳斯吉拉斯州费里费罗四角铁矿尾矿应力应变分析构成模型的比较评估
IF 0.5 Q4 ENGINEERING, GEOLOGICAL Pub Date : 2023-12-12 DOI: 10.28927/sr.2024.011022
André Faria, B. Delgado, Lucas Ferreira, Mauro Santos Junior
The study and understanding of the concepts related to critical state soil mechanics is relatively recent in Brazil, especially among practicing geotechnical engineers in the mining industry, where simpler solutions were traditionally adopted. This raises the necessity to develop studies capable of promoting discussions about the benefits of the approaches from the critical state theory. In this context, this research aims to evaluate the behavior of an iron ore tailings from the Quadrilátero Ferrífero through critical state computational models, considering the Modified Cam-Clay and NorSand model. The numerical results from the use of the models simulated the ductile/brittle behavior of the material in drained shear and it was observed that for loose samples both models produced similar results. The simulations in undrained shear, on the other hand, highlighted the differences between the models, with the NorSand showing a strength loss in undrained shear (strain-softening) whereas the Modified Cam-Clay Model exhibited a ductile behavior. In general, the NorSand model was the one that presented the best numerical response in relation to the experimental behavior, which may be linked to the use of the largest number of parameters, to the concept that particulate materials exist in a set of states and the silty characteristic of the material. Additionally, it was observed the difficulty to simulate the dense behavior of materials with the model, which may be associated with the formation of ‘shear bands’ during the experimental test and the complexity of modeling the occurrence of this phenomenon in virtual tests using the NorSand model.
在巴西,对临界状态土壤力学相关概念的研究和理解相对较晚,特别是在采矿业的岩土工程师中,传统上采用的是较为简单的解决方案。因此,有必要开展研究,以促进对临界状态理论方法益处的讨论。在此背景下,本研究旨在通过临界状态计算模型,考虑修正的 Cam-Clay 和 NorSand 模型,评估来自 Quadrilátero Ferrífero 的铁矿石尾矿的行为。使用这些模型模拟了材料在排水剪切时的韧性/脆性行为,数值结果表明,对于松散样本,两种模型产生的结果相似。另一方面,在排水剪切模拟中,两种模型之间的差异凸显出来,NorSand 模型在排水剪切中表现出强度损失(应变软化),而修改后的 Cam-Clay 模型则表现出延展性。总体而言,NorSand 模型是与实验行为相关的数值响应最好的模型,这可能与使用了最多的参数、颗粒材料存在于一系列状态的概念以及材料的淤泥特性有关。此外,还观察到模型模拟材料致密行为的难度,这可能与实验测试中 "剪切带 "的形成以及使用 NorSand 模型在虚拟测试中模拟这种现象的复杂性有关。
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引用次数: 0
Experimental study on mechanical behavior deterioration of undisturbed loess considering freeze-thaw action 考虑冻融作用的未扰动黄土力学行为退化试验研究
IF 0.5 Q4 ENGINEERING, GEOLOGICAL Pub Date : 2023-12-12 DOI: 10.28927/sr.2024.005822
Shuangshuang Yang, Yaling Chou, Li-jie Wang, Peng Zhang
To solve the problem that the mechanical behavior of undisturbed loess in seasonally frozen soil area is affected by freeze-thaw action, triaxial shear tests of undisturbed loess under freeze-thaw condition were carried out. The results show that the mechanical properties of undisturbed loess are greatly affected by factors including freeze-thaw process, water content, natural density and confining pressure. Freeze-thaw action has a certain impact on the failure surface shape and stress-strain curve. Before and after freeze-thaw, the shape of the shear failure surface is complex, including single oblique failure surface, double oblique failure surface, vertical failure surface, X-shaped failure surface, bulging failure, etc. And under the conditions of low water content, low confining pressure and high dry density, the stress-strain curve tends to be softened. Conversely, the curve tends to harden. Freeze-thaw action can make the stress-strain curve transition from softening to hardening. In addition, the freeze-thaw action significantly weakens the failure strength, shear strength, cohesion, initial tangent modulus and failure ratio of undisturbed soil, but does not change the internal friction angle obviously. Also, the heterogeneity of natural soil is also an important factor affecting the mechanical parameters, failure surface shape and stress-strain curve of undisturbed loess.
为了解决季节性冻土区未扰动黄土的力学行为受冻融作用影响的问题,对冻融条件下未扰动黄土进行了三轴剪切试验。结果表明,未扰动黄土的力学性能受冻融过程、含水量、天然密度和约束压力等因素的影响很大。冻融作用对破坏面形状和应力应变曲线有一定影响。冻融前后,剪切破坏面形状复杂,包括单斜破坏面、双斜破坏面、垂直破坏面、X 形破坏面、隆起破坏等。在低含水率、低约束压力和高干密度条件下,应力-应变曲线趋于软化。反之,曲线则趋于硬化。冻融作用可使应力-应变曲线从软化过渡到硬化。此外,冻融作用会显著削弱未扰动土壤的破坏强度、抗剪强度、内聚力、初始切线模量和破坏比,但不会明显改变内摩擦角。此外,天然土壤的异质性也是影响未扰动黄土力学参数、破坏面形状和应力应变曲线的重要因素。
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引用次数: 0
Effects of wetting and drying cycles on the swelling pressure and free swelling of expansive soil 干湿循环对膨胀土膨胀压力和自由膨胀的影响
Q4 ENGINEERING, GEOLOGICAL Pub Date : 2023-11-03 DOI: 10.28927/sr.2024.011122
Larissa Oliveira, Erinaldo Cavalcante
The aim of the current study is to investigate the influence of consecutive wetting and drying cycles on the free swelling and swelling pressure properties of a potentially expansive soil. The investigated sample consisting of high-plasticity inorganic clay with high consistencylimit values and extremely high swelling potential. The adopted methodology comprised free swelling and swelling pressure tests – based on the post-swelling loading method, under 0.5 kPa overload. Both tests were conducted in a cyclic manner by implementing eight wetting and drying cycles. Results have shown that the wetting and drying cycles acted as agents influencing the swelling pressure and free swelling properties of the expansive soil. It was found that the expansive soil sample, when moistened and then dried to its initial moisture content, time and again, showed higher values of swelling pressure and free swelling at the first moistening cycle. It was also observed that the expansive soil sample decreases its expansive behavior as the number of wetting and drying cycles increases.
本研究的目的是研究连续干湿循环对潜在膨胀土自由膨胀和膨胀压力特性的影响。所研究的样品由高塑性无机粘土组成,具有高浓度限值和极高的膨胀势。采用的方法包括自由膨胀和膨胀压力试验-基于膨胀后加载法,在0.5 kPa过载下。这两项试验都以循环的方式进行,通过实施8个湿润和干燥循环。结果表明,干湿循环是影响膨胀土膨胀压力和自由膨胀特性的因素。研究发现,膨胀土试样经多次湿润、再干燥至初始含水率后,在第一次湿润循环中膨胀压力和自由膨胀值均较高。随着干湿循环次数的增加,膨胀土试样的膨胀性能降低。
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引用次数: 0
The use of a video and a small-scale model for rain-induced landslides in geotechnical engineering education 在岩土工程教育中使用录影带及小型模型模拟雨水引致的山崩
Q4 ENGINEERING, GEOLOGICAL Pub Date : 2023-10-19 DOI: 10.28927/sr.2024.006623
Marcos Mendonça
Small-scale physical models of geotechnical problems are thought-provoking didactic tools that motivate students by arousing their curiosity and facilitating the understanding of physical phenomena and theoretical concepts. This work presents the development of an educational video about slope stability failures and its contributing factors. It shows several small-scale models built in a glass wall tank measuring 150 x 50 x 10 cm. Layers of fine gravel were placed on a sloping surface of polystyrene to represent a slope with a layer of residual soil on rock. Toy houses and cars were used to represent anthropogenic agents, and water with dye represents the groundwater flow. Each model depicts a different scenario of shallow slope failure. The objective of the video is to show that most slope failures in urban areas result from natural and anthropogenic factors. Several influence factors are shown: porewater level rise, excavation, surcharge application, and solid urban waste deposition. The 6-minute video has had more than 130,000 views on YouTube. Thanks to its simple and concise language, the video is shown in basic education and science museum, as well as in graduate and undergraduate courses. A questionnaire survey was carried out with undergraduate students to assess how helpful the video was for the learning process. This article explains the construction of the model, the video script, and the strategies for its use, as well as its reception. It was found that the video promoted motivational and learning benefits of providing context, establishing relevance, and teaching inductively.
岩土工程问题的小尺度物理模型是发人深省的教学工具,通过激发学生的好奇心和促进对物理现象和理论概念的理解来激励学生。这项工作提出了一个关于斜坡稳定失效及其影响因素的教育视频的发展。它展示了在一个150 x 50 x 10厘米的玻璃墙水箱中建造的几个小型模型。细砾石层被放置在聚苯乙烯的倾斜表面上,以代表岩石上有一层残余土壤的斜坡。玩具房子和汽车被用来代表人为因素,带染料的水代表地下水流动。每个模型都描绘了不同的浅层边坡破坏情景。这段视频的目的是表明,城市地区的大多数边坡失效是由自然和人为因素造成的。主要影响因素有:孔隙水位上升、开挖、堆积物的施用和城市固体垃圾的沉降。这段6分钟的视频在YouTube上的点击量已经超过13万次。由于语言简洁明了,该视频在基础教育和科学博物馆以及研究生和本科生课程中都有播放。研究人员对本科生进行了问卷调查,以评估该视频对学习过程的帮助。本文阐述了该模型的构建、视频脚本、使用策略以及接受情况。研究发现,该视频在提供情境、建立关联和归纳式教学方面具有促进动机和学习的作用。
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引用次数: 0
Methodological teaching-learning experiments applied to Geotechnical Engineering 方法教学实验在岩土工程中的应用
Q4 ENGINEERING, GEOLOGICAL Pub Date : 2023-10-19 DOI: 10.28927/sr.2024.004523
Silvio Ferreira
The use of problem-based and project-based learning is beneficial. The teaching-learning process requires the development of a critical, objective, and rational mind. This paper analyzes methodological experiments from the teaching-learning process carried out in the geotechnical area of the civil engineering program at three universities in the state of Pernambuco, Brazil, for more than 40 years. Three integrated experiments are presented. In the first experiment, undergraduate students in geotechnical engineering courses interacted with companies operating in the area, conducting laboratory and field tests and geotechnical instrumentation. The second experiment integrated students and teachers from different areas of the civil engineering program around a multidisciplinary project, while the third brought together undergraduate and graduate (master and doctoral) student research activities into a single project that extends from the development and construction of geotechnical equipment and applications of new soil improvement techniques to land use planning and occupation. )This study demonstrated the use of positive teaching-learning experiences carried out in the teaching of geotechnical engineering in the development of civil engineers who have technical skills and professional competences. It contributed to the advancement of knowledge in the development of new equipment, soil improvement, testing techniques and in the use, planning and occupation of soils. The interaction between the university, society and government institutions in problem solving also contributed.
使用基于问题和基于项目的学习是有益的。教学过程需要培养批判、客观和理性的思维。本文分析了巴西伯南布哥州三所大学土木工程专业岩土工程领域40多年来的教学过程中的方法实验。提出了三个综合实验。在第一个实验中,岩土工程课程的本科生与在该地区运营的公司进行互动,进行实验室和现场测试以及岩土仪器。第二个实验将来自土木工程不同领域的学生和教师围绕一个多学科项目进行整合,而第三个实验将本科生和研究生(硕士和博士)学生的研究活动整合到一个单一的项目中,该项目从岩土设备的开发和建设以及新土壤改良技术的应用扩展到土地利用规划和占用。本研究展示了在岩土工程教学中运用积极的教与学经验来培养具有技术技能和专业能力的土木工程师。它促进了新设备开发、土壤改良、测试技术以及土壤的使用、规划和占用方面知识的进步。大学、社会和政府机构在解决问题方面的相互作用也有所贡献。
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引用次数: 0
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