• Title/Summary/Keyword: Characteristics of ground behavior

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A Comparative Study of Structural Analysis on DCM Improved by Pile and Block Type (말뚝식과 블록식이 혼합된 시멘트혼합처리공법(DCM)의 구조체 해석 비교 연구)

  • Shin, Hyun Young;Kim, Byung Il;Kim, Kyoung O;Han, Sang Jae
    • Journal of the Korean Geotechnical Society
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    • v.30 no.4
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    • pp.5-19
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    • 2014
  • In this study, the structural analysis is performed on the method of shallow block and deep cement mixing pile, and then their characteristics and associated behaviors were analyzed. In the case of continuous beam analysis, the predicted settlement was very small, and shear force and bending stress are somewhat overestimated. The frame method is similar to numerical analysis in the internal force shallow block and long pile, but because the settlement of pile is underestimated, the additional calculation using the reaction of the long pile is necessary. For soil arching method and piled raft foundation method, the excessive axial force of long pile was predicted because the load sharing of pile is very large compared to the other methods. In the behavior of the shallow block and deep pile method, the settlement of shallow block and contact pressure are much in the center than the edge. In the estimating method considering the interaction between improved material and ground, the load sharing of the soil-cement pile ranges from 20% to 45%, and the stress ratio is 2.0~5.0 less than piled DCM. The maximum member forces at the boundary conditions of pile head are similar, but in fixed head the axial force and vertical displacement are different in accordance with pile arrangement.

Numerical Analysis for Dynamic Behavioral Characteristics of Submerged Floating Tunnel according to Shore Connection Designs (지반 접속부 설계에 따른 수중터널의 동적 거동 특성에 대한 수치해석적 연구)

  • Seok-Jun, Kang;Joohyun, Park;Gye-Chun, Cho
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.25 no.1
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    • pp.27-41
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    • 2023
  • Submerged floating tunnels must be connected to the ground to connect continents. The displacement imbalance at the shore connection between the underground bored tunnel and submerged floating tunnel can cause stress concentration, accompanying a fracture at the shore connection. The elastic joint has been proposed as a method to relive the stress concentration, however, the effect of the elastic joints on the dynamic behavior should be evaluated. In this study, the submerged floating tunnel and shore connection under dynamic load conditions were simulated through numerical analysis using a numerical model verified through a small-scaled physical model test. The resonant frequency was considered as a dynamic behavioral characteristic of the tunnel under the impact load, and it was confirmed that the stiffness of the elastic joint and the resonant frequency exhibit a power function relationship. When the shore connection is designed with a soft joint, the resonant frequency of the tunnel is reduced, which not only increases the risk of resonance in the marine environment where a dynamic load of low frequency is applied, but also greatly increases the maximum velocity of tunnel when resonance occurs.

An Experimental Study on Pullout Behavior of Shallow Bearing Plate Anchor (얕은 지압형 앵커의 인발거동특성에 관한 실험적 연구)

  • Hong, Seok-Woo;Kim, Hyung-Kong
    • Journal of the Korean Geotechnical Society
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    • v.30 no.2
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    • pp.5-18
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    • 2014
  • Depending on the underground load support mechanism, anchors are classified as friction anchors, bearing plate anchors and the recently developed combined friction-bearing plate anchors which combine the characteristics of both the friction and bearing plate type anchors. Even though numerous studies have been performed on bearing plate anchors, there were only few studies performed to observe the failure surface of bearing plate anchors. Furthermore most of the soil materials used on these tests were not real sand but carbon rods. In this study, sand was placed in the soil tank and laboratory tests were performed with bearing plate anchors installed with an embedment depth (H/h) ranging from 1~6. The variation in the pullout capacity and the behaviour of soil with the embedment depth (H/h) were observed. Ground deformation analysis program was also used to analyze soil displacement, zero extension direction, maximum shear strain contours. It was determined from the analysis of the results that at ultimate pullout resistance the deformation was 5 mm and the failure surface occurred in a narrower area when compared with results of the previous researches. It was also observed that the width of the fracture surface gradually becomes wider and expands up to the surface as the deformation increases from 10 mm to 15 mm.

The Effect of Cement Milk Grouting on the Deformation Behavior of Artifcial Rock Joints (시멘트현탁액 주입에 의한 신선한 암석절리의 역학적 특성 변화)

  • 김태혁;이정인
    • Tunnel and Underground Space
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    • v.10 no.2
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    • pp.180-195
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    • 2000
  • Grouting has been practiced as a reliable technique to improve the mechanical properties of rock mass. But, the study of ground improvement by greeting is rare especially in jointed rock mass. In this study, joint compression test and direct shear test were performed on pure rock joint and cement milk grouted rock joint to examine the grouting effect on the property of rock joint. In the pure rock joint compression test, joint closure varied non-linearly with normal stress. But after cement milk grouting, the normal deformation characteristics of the joint was linear at the low normal stress level. As normal stress increased. deformation of the sample rapidly increased due to the stress concentration at the joint asperities. Peak shear strength of the grouted joint in low normal stress was higher than that of non-grouted joint due to the cohesion, decreased exponetially as the grout thickness increased. Thus after cement milk grouting, the failure envelope modified to a curve that has cohesion due to grout material hydration with decreased friction angle. Shear stiffness and peak dilation angle of the grouted joint decreased as the grout thickness increased. The peak shear strength from the direct shear test on grouted rock joint was represented by an empirical equation as a fuction of grout thickness and roughness mean amplitude.

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An Evaluation of Allowable Bearing Capacity of Weathered Rock by Large-Scale Plate-Bearing Test and Numerical Analysis (대형평판재하시험 및 수치해석에 의한 풍화암 허용지지력 평가)

  • Hong, Seung-Hyeun
    • Journal of the Korean Geotechnical Society
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    • v.38 no.10
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    • pp.61-74
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    • 2022
  • Considering that the number of cases in which a structure foundation is located on weathered rock has been increasing recently, for adequate design bearing capacity of a foundation on weathered rock, allowable bearing capacities of such foundations in geotechnical investigation reports were studied. With reference to the study results, the allowable bearing capacity of a foundation on weathered rock was approximately 400-700 kN/m2, with a large variation, and was considered a conservative value. Because the allowable bearing capacity of the foundation ground is an important index in determining the foundation type in the early design stage, it can have a significant influence on the construction cost and period according to the initial decision. Thus, in this study, six large-scale plate-bearing tests were conducted on weathered rock, and the bearing capacity and settlement characteristics were analyzed. According to the test results, the bearing capacities from the six tests exceeded 1,500 kN/m2, and it shows that the results are similar with the one of bearing capacity formula by Pressuremeter tests when compared with the various bearing capacity formula. In addition, the elastic modulus determined by the inverse calculation of the load-settlement behavior from the large-scale plate-bearing tests was appropriate for applying the elastic modulus of the Pressuremeter tests. With consideration of the large-scale plate-bearing tests in this study and other results of plate-bearing tests on weathered rock in Korea, the allowable bearing capacity of weathered rock is evaluated to be over 1,000 kN/m2. However, because the settlement of the foundation increases as the foundation size increases, the allowable bearing capacity should be restrained by the allowable settlement criteria of an upper structure. Therefore, in this study, the anticipated foundation settlements along the foundation size and the thickness of weathered rocks have been evaluated by numerical analysis, and the foundation size and ground conditions, with an allowable bearing capacity of over 1,000 kN/m2, have been proposed as a table. These findings are considered useful in determining the foundation type in the early foundation design.

Sustainable Development and Sustainability Marketing - Integration of customer and socio-ecological aspect in Marketing concept - (글로벌 기업 환경 변화의 새로운 패러다임으로서 지속가능한 발전과 마케팅 - 지속가능마케팅의 의사결정 지향적 컨셉 -)

  • Nam, Sang-Min;Kim, Jong-Ho;Noh, Jung-Koo
    • Journal of Global Scholars of Marketing Science
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    • v.17 no.3
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    • pp.83-108
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    • 2007
  • Since the 1992 UN Conference for Environment and Development held in Rio de Jaineiro, Sustainable Development has become the global thesis. More than 170 countries signed the Agenda 21 for the sustainable action plan, and adopted the sustainability concept as the key concept of dealing with the environmental, social, ethical, and economic problem. Sustainability is one of the main marketing challenges in the 21st century. By integrating social and ecological criteria, marketing may can make valuable contributions to sustainable development. Regarding the sustainability marketing, it is difficult to find the domestic marketing research on the thesis of sustainable development, and this is the definite evidence that the Korean marketing researchers do not realize the importance of the thesis of sustainable development which is internationally suggested as the new paradigm of change. The purpose of this study is to build the conceptual background and explore the research direction in order to introduce and adopt the concept of sustainable development in the domestic marketing research field. The present paper proposes a comprehensive conception of sustainability marketing, defined by six step: analysis of social-ecological problems; analysis of consumer behavior; normative sustainability marketing; strategic sustainability marketing; instrumental sustainability marketing; and transformative sustainability marketing. The aim of the paper are to clarify the concept of sustainability marketing. To accomplish this research purpose we discuss the sustainable development which is the conceptual background of sustainability marketing, analyze the characteristics of the sustainability marketing, and finally summarize the research results and present the suggestions for further research. Sustainability marketing embraces the idea of sustainable development, a development that meets the needs of the present without compromising the ability of future generation to meet their own needs. Sustainability Marketing goes beyond conventional marketing thinking. If marketing is about satisfying customer needs and building profitable relationships with customers, sustainability marketing may be defined as building and maintaining sustainable relationships with customers, the social environment and natural environment. By creating social and environmental value, sustainability marketing tries to deliver and increase customer value. Sustainability Marketing aims at creating customer value, social value and environmental value. Sustainability marketing integrates social and ecological criteria into the whole process of marketing, and can be differentiated in six steps: (1) Analysis of the social and ecological problems, generally and specifically with respect to products which satisfy customer needs and wants; (2) Analysis of customer behavior with special aspect to social and ecological concerns; (3) Corporate commitments to sustainable development in the mission statement, development of sustainability visions, formulation of sustainable principles and guideline, setting of socio-ecological marketing objectives and goals (normative aspects of sustainability marketing); (4) Sustainability segmentation, targeting and positioning, and timing of market entry(strategic aspects of sustainability marketing); (5)Integration of social and ecological criteria into the marketing-mix, i.e. products, services and brands, pricing, distribution and communication(instrumental aspects of sustainability marketing); (6) Participation in public and political change processes, which transform existing institutions towards sustainability(transformative aspects of sustainability marketing). The first two steps begin with an analysis of the company situation. In sustainability marketing it is crucial not just to know consumer needs and wants, but also to find out about the ecological and social problems of products along their whole life cycle. The intersection of socio-ecological problems and consumer wants sets the ground for sustainability marketing. Step three to five describe the implementation of sustainability marketing. Social and ecological criteria are fully integrated into the mission statement, strategies and marketing-mix. Step six is one of the specifics of sustainability marketing. It is about the commitment of company to sustainable development and their active participation in public and political processes in order to change the existing framework in favor of sustainability.

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Research on Visitor Behavior and Satisfaction with the Nature Trail in Hallasan National Park (한라산국립공원 자연학습탐방로의 이용행태와 이용객만족에 관한 연구)

  • Kim, Jeong-Min
    • Korean Journal of Environment and Ecology
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    • v.21 no.3
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    • pp.223-234
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    • 2007
  • The study, executed with Hallasan National Park, which deserves to be a typical ecotourism destination, aims to provide basic information on park management for early establishment of ecotourism in a national park by assessing its visitors' behavior and satisfaction with a nature trail established as a series of an environmental interpretation program. The questionnaire survey was conducted at Eorimok Square in the weekday and on the weekend for two months of August and September in 2006, and finally 144 valid samples were used for the analysis. As a result of the research, it revealed that the demographic characteristics of the visitors to Hallasan National Park tended to coincide with those of the visitors to other national parks In Korea. On the whole, it showed their low recognition level of nature trails built up in national parks and less experience in using them. However, the visitors' satisfaction level and intention of re-visit, and recommendation to others were comparatively higher after actually using the nature trail at the site of Hallasan National Park, which hints at the possibility of national parks' much weightier role as the ground for ecology education and the functional expansion of the environmental interpretation-related facilities and programs. As for the attributes having effects on users' satisfaction with a nature trail, substantial aspects such as accessibility, safety, uniqueness and interest in environmental interpretation, and educational quality as well as physical facility management were revealed to have equal effects on users' satisfaction level, so there still remain a lot of pending issues over the reality of national parks in the initial stage of ecotourism staying at the level of the introduction and establishment of the facilities for environmental interpretation. This research had surveyed visitors to Hallasan National Park and limited to the nature trail only. For more systematic and practical ecological management of a national park, the in-depth understanding of the attributes affecting satisfaction of ecotourists, including nature trails and other environmental interpretation programs, and more sophisticated measuring tools are needed.

A Study on Teaching-Learning and Evaluation Methods of Environmental Studies in the Middle School (중학교 "환경" 교과의 교수.학습 및 평가 방법 연구)

  • 남상준
    • Hwankyungkyoyuk
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    • v.7 no.1
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    • pp.1-17
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    • 1994
  • This study was performed to determine appropriate teaching-learning and evaluation methods for Environmental Studies. To promote the relevance of our study to the needs of the schools and concerned educational communities of environmental education, we reviewed related literature, conducted questionnaire surveys, interviewed related teachers and administrator, held meetings with experts, and field-tested our findings. For selecting and developing teaching-learning methods of Environmental Studies, findings of educational research in general are considered. moreover, principles of environmental education, general aim of environmental education, orientations of environmental education, and developmental stages of middle school students in educational psychology were attended. In addition, relevance to the purpose of the Environmental Studies curriculum, appropriateness for value inquiry as well as knowledge inquiry, small group centered class organization, social interaction centered teaching-learning process, regional environmental situation, significance of personal environment, evaluation methods of Environmental Studies, multi- and inter-disciplinary contents of the Environmental Studies textbook, suitability to the evaluation methods of Environmental Studies, and emphasis on the social interaction in teaching-learning process were regarded. It was learned the Environmental Studies can be taught most effectively in via of holding discussion sessions, conducting actual investigation, doing experiment-practice, doing games and plate, role-playing and carrying out simulation activities, and doing inquiry. These teaching-learning methods were field-tested and proved appropriate methods for the subject. For selecting and developing evaluation method of Environmental Studies, such principles and characteristics of Environmental Studies as objective domains stated in the Environmental Studies curriculum, diversity of teaching-learning organization, were appreciated. We categorized nine evaluation methods: the teacher may conduct questionnaire surveys, testings, interviews, non-participatory observations; they may evaluate student's experiment-practice performances, reports preparation ability, ability to establish a research project, the teacher may ask the students to conduct a self-evaluation, or reciprocal evaluation. To maximize the effect of these methods, we further developed an application system. It considered three variables, that is, evaluates, evaluation objectives domains, and evaluation agent, and showed how to choose the most appropriate methods and, when necessary, how to combine uses of different methods depending on these variables. A sample evaluation instrument made on the basis of this application system was developed and tested in the classes. The system proved effective. Pilot applications of the teaching-learning methods and evaluation method were made simultaneously; and the results and their implications are as follows. Discussion program was applied in a lesson dealing with the problems of waste disposal, in which students showed active participation and creative thinking. The evaluation method used in this lesson was a multiple-choice written test for knowledge and skills. It was shown that this evaluation method and device are effective in helping students' revision of the lesson and in stimulating their creative interpretations and responces. Pupils showed great interests in the actual investigation program, and this programme was proved to be effective in enhancing students' participation. However, it was also turned out that there must be pre-arranged plans for the objects, contents and procedures of survey if this program is to effective. In this lesson, non-participatory observation methods were used with a focus on the attitudes of students. A scaled reported in general description rather than in grade. Experiment-practice programme was adopted in a lesson for purifying contaminated water and in this lesson, instruction objectives were properly established, the teaching-learning process was clearly specified and students were highly motivated. On the other hand, however, it was difficult to control the class when some groups of students require more times to complete their experiment, and sometimes different results. As regards to evaluation, performance observation test were used for assessing skills and attitudes. If teachers use well-prepared Likert scale, evaluation of all groups within a reasonablely short period of time will be possible. The most effective and successful programme in therms of students' participation and enjoyment, was the 'ah-nah-bah-dah-market' program, which is kind of game of the flea market. For better organized program of this kind, however, are essential, In this program, students appraise their own attitudes and behavior by responding to a written questionnaire. In addition, students were asked to record any anecdotes relating to self-appraisal of changes on one's own attitudes and behaviours. Even after the lesson, students keep recording those changes on letters to herself. Role-playing and simulation game programme was applied to a case of 'NIMBY', in which students should decide where to located a refuse dumping ground. For this kind of programme to e successful, concepts and words used in the script should be appropriate for students' intellectual levels, and students should by adequately introduced into the objective and the procedures of the lessons. Written questionnaire was used to assess individual students' attitudes after the lesson, but in order to acquire information on the changes of students' attitudes and skills, pre-test may have to be made. Doing inquiry programme, in which advantages in which students actually investigated the environmental influence of the areas where school os located, had advantages in developing students' ability to study the environmental problems and to present the results of their studies. For this programme to be more efficient, areas of investigation should be clearly divided and alloted to each group so that repetition or overlap in areas of study and presentation be avoided, and complementary wok between groups bee enhanced. In this programme, teacher assessed students' knowledge and attitudes on the basis of reports prepared by each group. However, there were found some difficults in assessing students' attitudes and behaviours solely on the grounds of written report. Perhaps, using a scaled checklist assessing students' attitudes while their presentation could help to relieve the difficulties.

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Change of Hydraulic Properties of Sand due to Fine Diatom Particle Migration (미세 Diatom 입자 이동에 의한 모래지반의 투수 특성 변화)

  • Pyo, Won-Mi;Lee, Jong-Sub;Lee, Joo Yong;Hong, Won-Taek
    • Journal of the Korean Geotechnical Society
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    • v.34 no.2
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    • pp.19-32
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    • 2018
  • During the process of gas hydrate extraction in the deep seabed, fine diatom particle migration occurs, which causes the seabed slope failure and the productivity deterioration of the gas hydrate. Therefore, a study related with the changes of the ground characteristics due to the fine particle migration is required. The objective of this study is to investigate the change of hydraulic properties of sand due to the migration of fine diatom particle in sandy soils. In order to simulate the sediments of the Ulleung basin gas hydrate in the East Sea, fifteen sand-diatom mixtures that have different diatom volume fractions (DVF) are prepared. During the falling head permeability tests, the coefficients of permeability are measured according to the DVF. In addition, for the simulation of the fine diatom particle migration, constant head permeability tests are conducted by applying the hydraulic pressures of 3 kPa, 6kPa, and 9 kPa on a specimen composed of two layers: a specimen with 50% DVF in upper layer and a specimen with 0% DVF in lower layer. Furthermore, the coefficient of permeability and the electrical resistivity of the migration zone are measured during the constant head permeability test. The falling head permeability tests show that the coefficient of permeability decreases as the DVF of the specimen increases. In addition, the gradient of the coefficient of permeability curve decreases in the DVF range of 10%~50% compared with that of 0%~10%, and increases above 50% in DVF. The result of constant head permeability tests shows that the coefficient of permeability decreases and electrical resistivity increases in the migration zone due to the fine diatom particle migration. This study demonstrates that fine diatom particle migration reduces the permeability of the soils and the behavior of the migration zone due to the fine diatom particle migration may be estimated based on the reversal relationship between the coefficient of permeability and the electrical resistivity.

Influence of the Existing Cavern on the Stability of Adjacent Tunnel Excavation by Small-Scale Model Tests (축소모형시험을 통한 공동이 근접터널 굴착에 미치는 영향평가)

  • Jung, Minchul;Hwang, Jungsoon;Kim, Jongseob;Kim, Seungwook;Baek, Seungcheol
    • Journal of the Korean GEO-environmental Society
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    • v.15 no.12
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    • pp.117-128
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    • 2014
  • Generally, when constructing a tunnel close to existing structures, the tunnel must be built at a constant distance from the structures that is more than width of tunnel to minimize the impact of interference between an existing structures and new tunnel. Spacing of these closed tunnels should be designed considering soil state, size of tunnel and reinforcement method. Particularly when the ground is soft, a care should be taken with the tunnel plans because the closer the tunnel is to the existing structures, the greater the deformation becomes. As methods of reviewing the effect of cavities on the stability of a tunnel, field measurement, numerical analysis and scaled model test can be considered. In the methods, the scaled model test can reproduce the engineering characteristics of a rock in a field condition and the shape of structures using the scale factor even not all conditions cannot be considered. In this study, when construction of a tunnel close to existing structures, the method and considering factors of the scaled model test were studied to predict the actual tunnel behavior in planning stage. Furthermore, model test results were compared with the numerical analysis results for verifying the proposed model test procedure. Also, practical results were derived to verify the stability of a tunnel vis-a-vis cavities through the scaled model test, which assumed spacing distances of 0.25 D, 0.50 D, and 1.00 D between the cavities and tunnel as well as the network state distribution. The spacing distances of 1.0 D is evaluated as the critical distance by the results of model test and numerical analysis.