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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 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 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 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 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
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
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
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
What kinds of educational material are useful for and desired by university instructors? The case of Geotechnical Engineering 什么样的教育材料对大学教师来说是有用的,也是他们想要的?岩土工程的案例
Pub Date : 2023-10-19 DOI: 10.28927/sr.2024.003623
Marina Pantazidou, Michele Calvello
Αn online questionnaire was developed to find out (i) whether geotechnical engineering instructors have available a variety of satisfactory educational material and (ii) the types of educational material they desire. The title of the questionnaire was phrased as “What Geotechnical Engineering Educational Material can we dream of?”, in order to convey that the main purpose of the survey project reported herein is to learn about these desired educational materials. In doing so, the survey also aims to assemble information on related issues, such as: existing educational materials, where do instructors search for them and how satisfied they are with available material. The questionnaire has 12 close-ended (four yes/no and eight multiple choice) and four open-ended questions. From the 94 completed questionnaires received, 63 were deemed to be conscientious attempts to answer its questions and were analyzed in detail. The most revealing findings from the close-ended questions include the following. The majority of the instructors (52%) are not adequately satisfied with the material they use. Likewise, whereas a significant percentage has searched for additional material, a little less than half of them (45%) are not satisfied with material found. Respondents need materials for their lectures, materials to engage students outside lecture time and, to a lesser extent, materials to assess students. In terms of topics of interest, case studies and laboratory-related educational materials are the most popular. The online supplement of the paper includes broad-stroke and fine-stroke descriptions of desirable educational materials that provide directions for developing them.
我们编制了一份网上问卷(Αn),以了解岩土工程导师是否有各种令人满意的教育资料,以及(ii)他们想要的教育资料类型。问卷的题目是“我们能想到什么样的岩土工程教材?”,以表达本文报告的调查项目的主要目的是了解这些所需的教育材料。在这样做的过程中,调查还旨在收集有关问题的信息,例如:现有的教育材料,教师在哪里寻找这些材料,以及他们对现有材料的满意程度。问卷有12个封闭式问题(4个是/否,8个选择题)和4个开放式问题。在收到的94份完成的问卷中,63份被认为是认真回答问题的尝试,并被详细分析。从封闭式问题中得出的最具启发性的发现包括以下几点。大多数教师(52%)对他们使用的材料不够满意。同样,尽管有相当大比例的人搜索了额外的材料,但其中不到一半(45%)的人对找到的材料不满意。受访者需要材料为他们的讲座,材料吸引学生讲课时间以外,在较小程度上,材料评估学生。就感兴趣的主题而言,案例研究和与实验室相关的教育材料是最受欢迎的。论文的在线补充包括对理想教材的粗线条和精细描述,为开发这些教材提供指导。
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引用次数: 0
An international initiative on geosynthetic education 关于土工合成教育的国际倡议
Pub Date : 2023-10-19 DOI: 10.28927/sr.2024.003823
Maria Almeida, Jorge Zornberg, Ennio Palmeira, Nathalie Touze
An international educational initiative to facilitate the exposure of geosynthetics to undergraduate civil engineering students has been conducted by the International Geosynthetics Society (IGS) for over a decade. Geosynthetics is a comparatively new topic within geotechnical engineering and, consequently, has only been sporadically introduced into undergraduate Civil Engineering curricula. In particular, geotechnical engineering professors themselves may have not been exposed to the basics of geosynthetics to be able to comfortably transfer such knowledge to their students. As part of this educational program, civil engineering professors are invited to take a course on geosynthetics, for which they receive fellowships covering their expenses. The course also includes complementary components such as a workshop consisting of practical demonstrations, pedagogical material, and technical documents. Implementation of the program involves multiple parties, including the IGS, its national chapters, and geosynthetics industry, who are allotted the responsibilities of supporting the program instructors, offering practical project-oriented input. This paper describes the course structure, the educational tools employed, the impact on the program caused by the pandemic, and results from feedback surveys that assessed how the knowledge on geosynthetics acquired by the participants was transferred to their students in terms of new courses on geosynthetics, inclusion of geosynthetics topics in existing undergraduate disciplines, etc. Emphasis is given on the experience of the Brazilian Chapter of IGS, which has already conducted programs. The educational outcomes of the programs currently offered are being evaluated and they suggest excellent acceptance of the course by participants and undergraduate students at the universities.
十多年来,国际土工合成学会(IGS)一直在开展一项国际教育倡议,以促进土工合成材料对土木工程本科学生的接触。土工合成材料是岩土工程中一个相对较新的课题,因此,只偶尔被引入土木工程本科课程。特别是,岩土工程教授自己可能没有接触到土工合成材料的基础知识,无法轻松地将这些知识传授给他们的学生。作为这个教育计划的一部分,土木工程教授被邀请参加一门关于土工合成材料的课程,为此他们获得了奖学金,以支付他们的费用。本课程还包括补充部分,如由实践演示、教学材料和技术文档组成的研讨会。该计划的实施涉及多方,包括IGS、其国家分会和土工合成材料行业,他们被分配了支持计划讲师的责任,提供实用的项目导向的投入。本文描述了课程结构、采用的教学工具、疫情对项目的影响,以及反馈调查的结果,这些调查评估了参与者获得的土工合成材料知识如何通过土工合成材料新课程、在现有本科学科中纳入土工合成材料主题等方式转移给学生。重点介绍了IGS巴西分会的经验,该分会已经开展了一些方案。目前提供的课程的教育成果正在进行评估,他们表明参与者和大学本科生对课程的接受程度很高。
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引用次数: 0
Interaction of geotechnics with society through education 土工技术与社会的互动教育
Pub Date : 2023-10-19 DOI: 10.28927/sr.2024.004023
Márcia Mascarenha, José Camapum de Carvalho, Andrelisa Jesus, Lilian Rezende, Mauricio Sales, Marta Luz
The Federal University of Goiás (UFG) and the University of Brasília (UnB), in partnership with the company Eletrobras Furnas, have developed research and, based on this, extension projects aimed at education in a broad sense, in which they seek to disseminate and popularise technical-scientific knowledge. This paper aims to present and evaluate educational actions carried out in the area of soil science and geotechnics applied to engineering, geography, and the environment. To do so, the educational experiences developed within the scope of two extension projects are shared. Beside that, the relevance of publishing books and primer, with language adapted to lay society, within the scope of research projects, is analyzed. The results collected regarding the effectiveness of the extension actions as a tool for learning point to a positive evaluation by the students. Furthermore, social networks are an important tool for scientific dissemination and have the potential to disseminate knowledge more widely than in a classroom course. By comparing the number of citations in Google Scholar of the books and booklets with the papers arising from these projects, one can observe the reach of this type of publication, although its purpose is the popularisation of science, with reach in places not considered in the technical-scientific publication metrics. Finally, for effective scientific development, it is necessary to have public policies, effective interaction between universities, research centres and schools, and the participation of professional associations, funding and evaluation agencies, Education Departments and the Ministry of Education, Science, Technology and Innovation.
Goiás联邦大学(UFG)和Brasília大学(UnB)同巴西电力公司合作进行了研究,并在此基础上开展了旨在广泛教育的推广项目,力求传播和普及技术科学知识。本文旨在介绍和评价在土壤科学和岩土技术应用于工程、地理和环境领域的教育行动。为此,我们分享了在两个扩展项目范围内发展起来的教育经验。此外,还分析了在研究项目范围内,以适应社会的语言出版书籍和读本的相关性。关于扩展行动作为学习工具的有效性,收集的结果指向学生的积极评价。此外,社会网络是科学传播的重要工具,具有比课堂课程更广泛传播知识的潜力。通过比较谷歌学者对这些书籍和小册子的引用次数与这些项目产生的论文的引用次数,人们可以观察到这类出版物的影响范围,尽管其目的是普及科学,其影响范围在技术-科学出版物指标中没有考虑到。最后,为了有效的科学发展,必须有公共政策,大学、研究中心和学校之间的有效互动,以及专业协会、资助和评估机构、教育部门和教育、科学、技术和创新部的参与。
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引用次数: 0
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Soils and Rocks
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