• 제목/요약/키워드: Time of Collapse

검색결과 583건 처리시간 0.025초

Study on failure and subsidence law of frozen soil layer in coal mine influenced by physical conditions

  • Zhang, Yaning;Cheng, Zhanbo;Lv, Huayong
    • Geomechanics and Engineering
    • /
    • 제18권1호
    • /
    • pp.97-109
    • /
    • 2019
  • Physical conditions play vital role on the mechanical properties of frozen soil, especially for the temperature and moisture content of frozen soil. Subsequently, they influence the subsidence and stress law of permafrost layer. Taking Jiangcang No. 1 Coal Mine as engineering background, combined with laboratory experiment, field measurements and empirical formula to obtain the mechanical parameters of frozen soil, the thick plate mechanical model of permafrost was established to evaluate the safety of permafrost roof. At the same time, $FLAC^{3D}$ was used to study the influence of temperature and moisture content on the deformation and stress law of frozen soil layer. The results show that the failure tensile stress of frozen soil is larger than the maximum tensile stress of permafrost roof occurring in the process of mining. It indicates that the permafrost roof cannot collapse under the conditions of moisture content in the range from 20% to 27% as well as temperature in the range from $-35^{\circ}C$ to $-15^{\circ}C$. Moreover, the maximum subsidence of the upper and lower boundary of the overlying permafrost layer decreases with the increase of moisture content in the range of 15% to 27% or the decrease of temperature in the range of $-35^{\circ}C$ to $-15^{\circ}C$ if the temperature or moisture content keeps consistent with $-25^{\circ}C$ or 20%, respectively.

Guyed Tower의 신뢰성 해석 (A Reliability Analysis of a Guyed Tower)

  • 하태범;최항순
    • 대한조선학회지
    • /
    • 제24권2호
    • /
    • pp.29-35
    • /
    • 1987
  • As offshore activities move into deeper ocean, conventional fixed-base platforms drastically increase in size and cost, One of alternatives available is a guyed tower, in which environmental loads are supported by guylines instead of structural members. The guying system of the guyed tower is designed on one hand to be stiff enough to limit the structural displacement in normal operations, but on the other hand to be soft enough to permit large slow sways during the presence of design-level storms. This compliancy provides an efficient means of withstanding harsh environment so that the disproportionate increase in size of deep water platforms can be kept to a rational limit. Novel configurations contain always some degrees of potential risks mainly due to the lack of experience. The most critical hazard inherent to a guyed tower may be the pullout of anchor piles. Once it happens, the guyline fails to function and it may eventually lead to the total collapse of the system. It is the aim of this paper to discuss and quantify the anchor-pullout risk of a guyed tower. A stochastic analysis is made for evaluating the first-upcrossing probability of the tension acting on anchor piles over the uplift capacity. Nonlinearities involved in the mooring stiffness and hydrodynamics are taken into account by using time-domain analysis. A simplified two dimensional dynamic model is developed to exemplify the underlying concept. Real hurricane data in the Gulf of Mexico spanning over 70 years are incorporated in a numerical example of which result clearly indicates highly potential risk of anchor pullout.

  • PDF

Effect of Neem (Azadirachta indica) oil on the progressive growth of a spontaneous T cell lymphoma

  • Mallick, Sanjaya Kumar;Gupta, Vivekanand;Singh, Mahendra Pal;Vishvakarma, Naveen Kumar;Singh, Nisha;Singh, Sukh Mahendra
    • Advances in Traditional Medicine
    • /
    • 제7권5호
    • /
    • pp.459-465
    • /
    • 2008
  • The present study was undertaken to investigate the effect of in vivo administration of neem oil intra-peritoneally (i.p.) to mice bearing a progressively growing transplantable T cell lymphoma of spontaneous origin, designated as Daltons lymphoma (DL), on the tumor growth. Mice were administered various doses of neem oil mixed in groundnut oil, which was used as a diluting vehicle or for administration to control DL-bearing mice. Administration of neem oil resulted in an acceleration of tumor growth along with a reduction in the survival time of the tumor-bearing host. Neem oil administered DL-bearing mice showed an augmented apoptosis in splenocytes, bone marrow cells and thymocytes along with an inhibition in the anti-tumor functions of tumor-associated macrophages. Thus this study gives an altogether a novel information that neem oil instead of the popular belief of being anti-tumor and immunoaugmentary may in some tumor-bearing conditions, behave in an opposite way leading to an accelarated tumor progression along with a collapse of the host's anti-tumor machinery. These observations will thus have long lasting clinical significance, suggesting caution in use of neem oil for treatment of cancer.

Practical relations to quantify the amount of damage of SWRCFs using pushover analysis

  • Habibi, Ali Reza;Samadi, Mohammad;Izadpanah, Mehdi
    • Advances in concrete construction
    • /
    • 제10권3호
    • /
    • pp.271-278
    • /
    • 2020
  • Quantifying the amount of damage of structures under earthquakes is an interesting issue that researchers have attended on and have presented some damage indices. Whereas a lot of damage indices have been introduced based on nonlinear dynamic analysis, computational effort, the calculus complicacy and time-consuming of this analysis are the main drawbacks to widespread use of these indices. The objective of this study is to quantify the damage of Shear Wall Reinforced Concrete Frames (SWRCFs) based on pushover analysis as a procedure that can reflect the behavior of structures from elastic to collapse. For this purpose, firstly, several SWRCFs are designed and the capacity spectrum of each one is achieved via pushover analysis. After that, the static damage indices of the designed frames are obtained. Then, nonlinear dynamic analyses are performed on these frames and the Park and Ang damage index as the basis damage criterion is achieved. Afterward, some relations are presented to predict the dynamic damage of these frames via pushover analysis. Eventually, to confirm the validity of the proposed relations, the values of Park and Ang damage index of three new SWRCFs are acquired once utilizing nonlinear dynamic analysis and again applying the introduced relations. Outcomes prove the validity of some presented damage indices.

북한의 동.서의 결합 (The combination of the traditional and the modern medicine in North Korea)

  • 김창엽;이상구;임병묵
    • 대한예방한의학회지
    • /
    • 제4권2호
    • /
    • pp.108-118
    • /
    • 2000
  • According to the North Korean documents , North Korean government have emphasized the development of the Koryo medicine (traditional korean medicine) and encouraged the combination of the Koryo and the modern medicine. It is regarded that this attitude arose from the ruler's will toward independency in the medical field and at the same time the lack of modern medical resources . Combinations of the Koryo medicine and the modern medicine in the clinical textbooks are classified as follows: first, mixed medication of the Koryo and the modern medicine. Second, combination of the traditional acupuncture(or moxibustion) and the medication of modern medicines. Third, injection of modern medicines at acupoints. Forth, an intramuscular or an intravenous injection of the Koryo medicine. Fifth, anesthesia using Koryo medicine. Sixth, simple surgery at the acupoints. Lastly, combination of injection and the traditional therapy(eg. acupuncture, moxibustion and cupping) Despite of many achievements in the field of combined medical treatment, recent economic failure and severe famine for several years caused collapse of the health care delivery system in North Korea, and it is hard to find combined practices actually.

  • PDF

Dent 손상을 갖는 원통부재의 최종강도에 관한 연구(제2보) -굽힘 하중을 받는 경우- (Ultimate Strength of Dented Tubular Members(2nd report) -under Bending Loads-)

  • 노인식;전태병;조병삼
    • 대한조선학회논문집
    • /
    • 제41권6호
    • /
    • pp.56-64
    • /
    • 2004
  • Several types of steel structures which are employed in offshore petroleum activities are constructed with tubular members. These structures are usually subjected to various types of loads such as normal functional loads and environmental loads. Furthermore, accidental loads may also act on the leg or bracing members due to supply boat collisions and objects droppings from platform decks. The extent of damage caused by these loads ranges from total collapse of the structure to small damage which may not have serious consequence at the time of accident. To make optimal design decisions regarding structural safety and economical efficiency, it is very important to be able to assess the influence of damages on the performance of damaged structural members. In the End report, a series of calculations is performed to study the effects of different parameters on the load carrying capacity of such damaged members under pure bending. And the results of analysis are compared with experiment results.

Improving Durability Performance of Reinforced Concrete Structures with Probabilistic Analysis

  • Ferreira, Rui Miguel
    • International Journal of Concrete Structures and Materials
    • /
    • 제2권2호
    • /
    • pp.137-143
    • /
    • 2008
  • In recent years, much research work has been performed on durability design and long-term performance of concrete structures in marine environments. In particular, the development of new procedures for probability-based durability design has been shown to provide a more realistic basis for the analysis. This approach has been successfully applied to several new concrete structures, where requirements for a more controlled durability and service life have been specified. For reinforced concrete structures in a marine environment, it is commonly assumed that the dominant degradation mechanism is the corrosion of the reinforcement due to the presence of chlorides. The design approach is based on the verification of durability limit states, examples of which are: depassivation of reinforcement, cracking and spalling due to corrosion, and collapse due to cross section loss of reinforcement. With this design approach the probability of failure can be determined as a function of time. In the present paper, a probability-based durability performance analysis is used in order to demonstrate the importance of the durability design approach of concrete structures in marine environments. In addition, the sensitivity of the various durability parameters affecting and controlling the durability of concrete structures in a marine environment is studied. Results show that the potential of this approach to assist durability design decisions making process is great. Based the crucial information generated, it is possible to prolong the service life of structures while simultaneously optimizing the final design solution.

Transient rheological probing of PIB/hectorite-nanocomposites

  • Sung, Jun-Hee;Mewis, Jan;Moldenaers, Paula
    • Korea-Australia Rheology Journal
    • /
    • 제20권1호
    • /
    • pp.27-34
    • /
    • 2008
  • Clay suspensions in liquid polymers exhibit a time-dependent behaviour that includes viscoelastic as well as thixotropic features. Because of the presence of interacting clay platelets, particulate networks can develop, which are broken down during flow and rebuild upon cessation of the flow. Here, the use of thixotropic techniques in probing flow-induced structures in nanocomposites is explored with data on a hectorite-poly(isobutylene) model system. By means of fast stress jump measurements the hydrodynamic contributions to the steady state stresses are determined as well as those caused by the stretching of the clay floes. Flow reversal measurements do not provide a clear indication of flow-induced anisotropy in the present case. The recovery of the clay microstructure upon cessation of flow is followed by means of overshoot and dynamic measurements. The development of a particulate network is detected by the appearance and growth of a low frequency plateau of the storage moduli. The modulus-frequency curves after various rest times collapse onto universal master curves, regardless of the pre-shear history or temperature. The scaling factors for this master curve are the crossover parameters. The crossover moduli are nearly a linear function of the crossover frequency, the relation being identical for recovery after shearing at different shear rates. This function depends, however, on temperature.

후기자본주의 사회의 패션에 나타난 혼성모방 (Pastiche in the late Capitalism Fashion)

  • 김민자
    • 복식
    • /
    • 제50권
    • /
    • pp.69-84
    • /
    • 2000
  • Th purpose of this study is three folds: to analyze postmodern fashion through the notion of pastiche to enhance an understanding of uncertain and confused situation in the late 1990s and to suggest a way of approach to creativity and originality in recent fashion design. The results can be summarized as follows: 1. Pastiche is an art work that borrows some parts of other artists authentic works and recombines them thus imitating their style technique or motifs selfconciously. 2. Pastiche is based onthe Deconstruction theory: the end of art as a result of deconstruction of the subject the collapse of the meaning the loss of history: the late Capitalism in which reality becomes chage into images or simulacre. 3. Pastiche represented by the death of author which means the exhaustion of creativity is shown in the fashion borrowing subculture styles and art works or religious images. Pastiche fashion which is equal to the play of signifiers floated as image is shown as graffiti and objects Time and space pastiche fashion can be explained by historical eclectism and ethnic looks, Finally pastiche means not the fixed aspect but the open concept of indeterminate condition which includes " anything goes" through the coesistence of various style in pastiche fashion.

  • PDF

혁명적 변화에 나타난 NEW FASHION의 발생 및 특징에 관한 연구 - CHRISTIAN DIOR의 THE NEW LOOK을 중심으로 - (A Study on the Generation and Characteristic of New Fashion Found in Changes in Revolutionary Fashion - Focused on the New Look of Christian Dior -)

  • 곽태기
    • 복식
    • /
    • 제51권1호
    • /
    • pp.129-143
    • /
    • 2001
  • Particular historic events such as revolution and wars have given rise to fashion. Luxurious costume representative of the aristocratic culture since the French Revolution was changed into popular look with the collapse of the royal regime. With the restoration of the royal regime by Napoleon, rapid changes associated with the reemergence of the costume of aristocratic brought an opportunity for the revolutionary fashion of bringing about new fashion in the fashion field. Especially, the New Look Presented by Christian Dior in 1947 shortly after the Second World War would be the typical style of revolutionary fashion. Accordingly, this study attempted to analyse the characteristics of new fashion regarding how new fashion occurred and developed in changes in revolutionary fashion after the Revolution and the War, in conjunction with the zeitgeist(time split) of rapid social changes. The ultimate purpose of this study was find out the significance of fashion as to how and why fashion changed in relation to the factors of changes in fashion in the history and create new future fashion by reinterpreting new aesthetic consciousness about the characteristic of new fashion found in changes in revolutionary fashion.

  • PDF