In-service hydrocarbons must be transported at high temperature and high pressure to ease the flow and prevent the solidification of the wax fraction. The pipeline containing hot oil will expand longitudinally due to ...In-service hydrocarbons must be transported at high temperature and high pressure to ease the flow and prevent the solidification of the wax fraction. The pipeline containing hot oil will expand longitudinally due to the rise in temperature. If such expansion is resisted, for example by frictional effects over a kilometer or so of pipeline, compressive axial stress will be built up in the pipe-wall. The compressive forces are often so large that they induce vertical buckling of buffed pipelines, which can jeopardize the structural integrity of the pipeline. A typical initial imperfection named continuous support mode of submarine pipeline was studied. Based on this type of initial imperfection, the analytical solution of vertical thermal buckling was introduced and an elastic-plasticity finite element analysis （FEA） was developed. Both the analytical and the finite element methodology were applied to analyze a practice in Bohai Gulf, China. The analyzing results show that upheaval buckling is most likely to build up from the initial imperfection of the pipeline and the buckling temperature depends on the amplitude of initial imperfection. With the same amplitude of initial imperfection, the triggering temperature difference of upheaval buckling increases with covered depth of the pipeline, the soil strength and the friction between the pipeline and subsoil.展开更多
In this paper,a theoretical solution of vertical buckling is proposed with regard to the typical initial imperfection cases of submarine pipelines.Analytical tools are applied to predicting the occurrence and conseque...In this paper,a theoretical solution of vertical buckling is proposed with regard to the typical initial imperfection cases of submarine pipelines.Analytical tools are applied to predicting the occurrence and consequence of inservice buckling of a buried heated pipeline in Bohai Gulf.An evaluation is performed to ensure the pipeline structural integrity during operation under loading conditions.Different protection measures are proposed and their validities are analyzed.Analyses show that for the same magnitude of initial imperfection,the upheaval buckling of pipeline with isolated prop model is the most likely to occur.The empathetic model represents a special sub-case of continuous prop model,and the calculated buckle temperature is between the first stage and the second stage of post-upheaval buckling of continuous prop model.And the larger the initial imperfection,the less the axial force required for the upheaval buckling.Meanwhile,it can be seen that a peak point appears on the curves of temperature difference against buckling amplitude for small initial imperfection.Besides,trenching-burial is one kind of protection measures preventing the pipeline from thermal upheaval.The covered depth-to-diameter ratio depends on the design conditions and subsoil properties.For the given pipeline in this paper,the covered depth-to-diameter ratio is recommended to be 5.展开更多
In-service hydrocarbons must be transported at high temperature and high pressure to ease the flow and to prevent the solidification of the wax fraction. The high temperature and high pressure will induce the addition...In-service hydrocarbons must be transported at high temperature and high pressure to ease the flow and to prevent the solidification of the wax fraction. The high temperature and high pressure will induce the additional stress in the pipeline, which results in the upheaval buckling of the pipeline. If such expansion is resisted, e.g., by the frictional effects of the foundation soil over a kilometer or of a pipeline, the compressive axial stress will be set up in the pipe-wall. When the stress exceeds the constraint of the foundation soil on the pipeline, suddenly-deforming will occur to release the internal stress, similar to the sudden deformation of the strut due to stability problems. The upheaval buckling may jeopardize the structural integrity of the pipeline. Therefore, effective engineering measures against this phenomenon play an important role in the submarine pipeline design. In terms of the pipeline installation and protection measures commonly used in Bohai Gulf, three engineering measures are investigated in great details. An analytical method is introduced and developed to consider the protection effect of the anti-upheaval buckling of the pipeline. The analysis results show that the amplitude of the initial imperfection has a great effect on the pipeline thermal upheaval buckling. Both trenching and burial and discrete dumping are effective techniques in preventing the pipeline from buckling. The initial imperfection and operation conditions of the pipelines determine the covered depth and the number of layers of the protection measures.展开更多
Damming landslides are very common in China, they ever blocked the rivers and streams completely or partly, and form natural lakes. Now more than 150 damming landslides in China are recognized through field investigat...Damming landslides are very common in China, they ever blocked the rivers and streams completely or partly, and form natural lakes. Now more than 150 damming landslides in China are recognized through field investigation and data collection indoors. These Landslides distribute in steep mountainous counties around the Qinghai—Tibet Plateau, and mainly of which in southwest China and northwest China.. Studies show that the distribution of damming landslides has a close relation with the event of the Tibet plateau upheaval. The thermodynamic effect on the free atmosphere results from rapid upheaval of Qinghai\|Tibet plateau is more and more intensive, it causes air to circulate from east to west. In winter, the high Tibet Plateau leads the cool air gather quickly and high cool potential to be stronger. On one side, an anticyclone cool high pressure forms near the ground surface at the altitude of 4000～5000m, and produces winter monsoon wind. On the other side, the shielding effect of the plateau impedes the air from Siberia touching with the air from south Indian Ocean, which causes the cool air from Siberia enters China frequently and strengthens the cool and drought in northwest China. In summer, the monsoon wind is impeded by the plateau and cannot enter into north China, where it is dry, it can only moves around the plateau and at the edge enters into southwest, south, middle and east China, where the rainfall process is strong. Thus south and east of the plateau become the areas with many damming landslides resulted from heavy rain.展开更多
Upheaval buckling of pipelines can occur under thermal expansion and differential ground settlement.Research on this phenomenon has usually assumed the pipes are buried in horizontal ground.For long-distance transmiss...Upheaval buckling of pipelines can occur under thermal expansion and differential ground settlement.Research on this phenomenon has usually assumed the pipes are buried in horizontal ground.For long-distance transmission pipelines across mountainous areas,the ground surface is commonly inclined.Based on the Rankine earth pressure theory and Mohr-Coulomb failure criterion,analytical formulae for calculating the peak uplift resistance and the slip surface angles for a buried pipe in inclined ground are presented in this paper.Analyses indicate that the slip surfaces in inclined ground are asymmetric and rotate towards the downhill side.Under a shallow burial depth,the failure plane angle is highly impacted by the ground inclination.When the embedment ratio(H/D)is more than 4,the influence of the ground slope on the failure plane angle is negligible.The peak uplift resistance reduces in inclined ground,especially when H/D is less than 1.Finally,a simple equation considering the impact of ground inclination is proposed to predict the peak uplift resistance.展开更多
From April 14 to 18,Chinese President Xi Jinping made state visits to Vietnam,Malaysia,and Cambodia.This tour coincided with global upheaval caused by“reciprocal tariffs”imposed by U.S.President Donald Trump,which t...From April 14 to 18,Chinese President Xi Jinping made state visits to Vietnam,Malaysia,and Cambodia.This tour coincided with global upheaval caused by“reciprocal tariffs”imposed by U.S.President Donald Trump,which turned global eyes towards China and Southeast Asian nations to see how they would strengthen cooperation and respond to the“Trump effect.”展开更多
This paper presents a dynamic modeling method to test and examine the minimum mass of pressurized pore-gas for triggering landslides in stable gentle soil slopes.A stable gentle soil slope model is constructed with a ...This paper presents a dynamic modeling method to test and examine the minimum mass of pressurized pore-gas for triggering landslides in stable gentle soil slopes.A stable gentle soil slope model is constructed with a dry cement powder core,a saturated clay middle layer,and a dry sand upper layer.The test injects H_(2)O_(2)solution into the cement core to produce new pore-gas.The model test includes three identical H_(2)O_(2)injections.The small mass of generated oxygen gas(0.07%of slope soil mass and landslide body)from the first injection can build sufficient pore-gas pressure to cause soil upheaval and slide.Meanwhile,despite the first injection causing leak paths in the clay layer,the generated small mass of gas from the second and third injections can further trigger the landslide.A dynamic theoretical analysis of the slope failure is carried out and the required minimum pore-gas pressure for the landslide is calculated.The mass and pressure of generated gas in the model test are also estimated based on the calibration test for oxygen generation from H_(2)O_(2)solution in cement powder.The results indicate that the minimum mass of the generated gas for triggering the landslide is 2 ppm to 0.07%of the landslide body.Furthermore,the small mass of gas can provide sufficient pressure to cause soil upheaval and soil sliding in dynamic analysis.展开更多
Fission-track, (U-Th)/He thermochronology, and cooling properties indicate that the southern Daba arcuate zone (SDBAZ) underwent a distinctive phase of rapid cooling in 153-100 Ma at a rate of 1.44-1.90°C/Ma. Thi...Fission-track, (U-Th)/He thermochronology, and cooling properties indicate that the southern Daba arcuate zone (SDBAZ) underwent a distinctive phase of rapid cooling in 153-100 Ma at a rate of 1.44-1.90°C/Ma. This rapid uplifting strongly contrasts with (1) the previous, rapid foreland subsidence during Early to Middle Jurassic in response to late-orogenic compression from the Qinling belt, (2) the succeeding long, slow cooling phase and relative thermal stability that occurred during the 100-45 Ma period. This rapid cooling event in the SDBAZ parallels those experienced by two adjacent upheavals of Huangling (HLUZ) and Hannan-Micang (HMUZ), with cooling rates of 2.22-3.17°C/Ma for the HLUZ in 160-126 Ma, 4.91°C/Ma for the southern HMUZ in 150-125 Ma, as well as 2.11°C/Ma for the northern HMUZ in 150-105 Ma. Comparing thermal histories among the SDBAZ, the HLUZ, the HMUZ, and the Wudang metamorphic zone (WDMZ), we infer that the Daba arcuate structural belt formed in 153-100 Ma. The combined dating data support a correlation with a low-angle arcuate south-thrusting of the Qinling orogen triggered by northward convergence of the Yangtze Craton, contemporaneously encountering rigid basement obstructions from the HLUZ and the HMUZ, respectively. Both the SDBAZ and neighboring domains additionally underwent a comparatively fast cooling and uplift since about 45 Ma.展开更多
The fundamental motivation leading to the Middle East Upheaval is an urgent need for the internal political and social transformation in Middle East countries.International public opinion,particularly the Western disc...The fundamental motivation leading to the Middle East Upheaval is an urgent need for the internal political and social transformation in Middle East countries.International public opinion,particularly the Western discourse that occupies a stronger position has had a profound impact on the development of the whole situation.With China’s continued rise,there is an increase in its competitions and frictions with the United States and other Western powers in global political,economic and other areas.The West uses its advantages in controlling international public opinion,and continues to manufacture discourse and set agendas and even slander regarding Chinese policies.This is not only to guide the situation,but more to maintain its dominant position in international affairs and to contain China’s rising influence.In recent years,China has taken a more aggressive Middle East policy.However,its ability to construct discourse and set agendas is relatively lacking.Therefore,China often remains passive and reactive when responding to the traps set in the Western discourse and agendas.This article focuses on the international competition for discourse power in the Middle East upheaval and the implications for china.展开更多
Arab countries have been faced with a large scale Middle Eastern upheaval,which has attracted the attention of all the Middle Eastern countries and international community.The current situation is primarily related to...Arab countries have been faced with a large scale Middle Eastern upheaval,which has attracted the attention of all the Middle Eastern countries and international community.The current situation is primarily related to the important location of the Middle East.Nearly all the Arab countries are involved in the upheaval.Omnifarious appeals are claimed by the people,including political,economic and social aspects.The problems have been accumulating for years,and the Middle East upheaval in 2011 was an overall outburst of people’s dissatisfaction.The cost of the unrest is high despite the social progress it may promote.At present,a fragile peace is realized in Syria though the prospect of future development is unclear.Since the outbreak of the Middle East upheaval,China has adopted a principle of“non-intervention in other’s internal affairs”and“mediating for peace while promoting talks”policy,which is appropriate and proactive.China should adhere to this practice in the future despite the voices of opposition and temporary misunderstanding.展开更多
Due to more than one-year’s upheaval,many Middle Eastern countries experienced regime change,and Syria is the next target and center of this political swirl.The rise of Islamic force is a serious problem for these co...Due to more than one-year’s upheaval,many Middle Eastern countries experienced regime change,and Syria is the next target and center of this political swirl.The rise of Islamic force is a serious problem for these countries in transition to deal with.Because of this upheaval,the Middle Eastern configuration is facing challenges;the contradiction within regional powers is experiencing growth and decline.The adjustment of America’s Middle East policy has affected the trend of Middle East situation.China’s“non-interference in others’internal affairs”principle gains international society’s interpretation,and China’s diplomacy towards the Middle East is facing important opportunity and enormous challenges.China should seize the opportunity and seek the new development of China-Middle East relations.展开更多
Prior to the Middle East upheavals,democratic transitions in Arab countries could be roughly divided into three stages,namely,the early constitutional reform,the third wave of democratization and democratic reforms un...Prior to the Middle East upheavals,democratic transitions in Arab countries could be roughly divided into three stages,namely,the early constitutional reform,the third wave of democratization and democratic reforms under the impact of the end of the Cold War,and during the democratization process under pressure from the US“Greater Middle East”initiative in the new century.The Middle East upheavals are part of political and social movements that involve the whole Arab world.They have not only some common features,but also huge differences;the long-standing problems in Arab countries in the political,economic and social areas are the fundamental causes of Middle East upheavals.However,in addition to this,they are also affected by the US“Greater Middle East”initiative and other external factors.Democratic reforms and transitions undoubtedly constitute an important part of the Middle East upheavals.Arab countries are currently carrying out democratic reforms,but meanwhile they are also facing many challenges.The core elements that affect the progress of democratic transitions include three factors:Islam,military intervention and geopolitical factors.With respect to the relationship between Islam and democratic transition,the conflicts between religious and secular forces will continue to have an impact on the democratic transition of the Arab countries.0n the other hand,moderate Islamic forces will explore democratization with Islamic characteristics.The relationship between Islam and democracy will be developing in diversified ways,and consecutively adjusting and remodeling.In terms of relationship between military intervention and the democratic transition,there will be a long way to eliminate the impact of military intervention in Arab countries,and a long process from the starting of democracy to democratic consolidation,and eventually to democratic functioning.This also depends on the normalization of relations between religious and secular forces after a long period of interaction and accommodation.On the relationship between geopolitics and democratic transition,complicated internal religious,sectarian and ethnic conflicts,contradictions among Arab countries,ideological competition and regional leadership competition,as well as the military intervention and exports of democracy from Western powers,have exacerbated the turbulence in the Arab democratic transition.展开更多
Reliable assessment of uplift capacity of buried pipelines against upheaval buckling requires a valid failure mechanism and a reliable real-time monitoring technique.This paper presents a sensing solution for evaluati...Reliable assessment of uplift capacity of buried pipelines against upheaval buckling requires a valid failure mechanism and a reliable real-time monitoring technique.This paper presents a sensing solution for evaluating uplift capacity of pipelines buried in sand using fiber optic strain sensing(FOSS)nerves.Upward pipe-soil interaction(PSI)was investigated through a series of scaled tests,in which the FOSS and image analysis techniques were used to capture the failure patterns.The published prediction models were evaluated and modified according to observations in the present study as well as a database of 41 pipe loading tests assembled from the literature.Axial strain measurements of FOSS nerves horizontally installed above the pipeline were correlated with the failure behavior of the overlying soil.The test results indicate that the previous analytical models could be further improved regarding their estimations in the failure geometry and mobilization distance at the peak uplift resistance.For typical slip plane failure forms,inclined shear bands star from the pipe shoulder,instead of the springline,and have not yet reached the ground surface at the peak resistance.The vertical inclination of curved shear bands decreases with increasing uplift displacements at the post-peak periods.At large displacements,the upward movement is confined to the deeper ground,and the slip plane failure progressively changes to the flow-around.The feasibility of FOSS in pipe uplift resistance prediction was validated through the comparison with image analyses.In addition,the shear band locations can be identified using fiber optic strain measurements.Finally,the advantages and limits of the FOSS system are discussed in terms of different levels in upward PSI assessment,including failure identification,location,and quantification.展开更多
The buckling of submarine pipelines may occur due to the action of axial soil frictional force caused by relative movement of soil and pipeline, which is induced by the thermal and internal pressure. The likelihood of...The buckling of submarine pipelines may occur due to the action of axial soil frictional force caused by relative movement of soil and pipeline, which is induced by the thermal and internal pressure. The likelihood of occurrence of this buckling phenomenon is largely determined by soil resistance. A series of large-scale model tests were carried out to facilitate the establishment of substantial data base for a variety of burial pipeline relationships. Based on the test data, nonlinear soil spring can be adopted to simulate the soil behavior during the pipeline movement. For uplift resistance, an ideal elasticity plasticity model is recommended in the case of H/D （depth-to-diameter ratio）〉5 and an elasticity softened model is recommended in the case of H/D≤5. The soil resistance along the pipeline axial direction can be simulated by an ideal elasticity plasticity model. The numerical analyzing results show that the capacity of pipeline against thermal buckling decreases with its initial imperfection enlargement and increases with the burial depth enhancement.展开更多
Predicting and estimating the response of sub- way tunnel to adjacent excavation of foundation pit is a research focus in the field of underground engineering. Based on the principle of two-stage method and incre- men...Predicting and estimating the response of sub- way tunnel to adjacent excavation of foundation pit is a research focus in the field of underground engineering. Based on the principle of two-stage method and incre- mental method, an analytic approach is suggested in this paper to solve this problem in an accurate and rapid way, and the upheavals of tunnel due to adjacent excavation are solved by analytic method. Besides, the presented method is used in the practical engineering case of Shenzhen Metro Line 11 and verified by numerical simulation and in situ measurement. Finally, a parametric analysis is performed to investigate the influence of different factors on tunnel＇s deflection. Some useful conclusions have been drawn from the research as below： The deflection results of tunnel obtained from analytic method are nearly consistent with the results getting from numerical analysis and measured data, which verified the accuracy and rationality of pre- sented method. The excavation size has a significant impact on both the displacement values and influenced range of tunnel. However, the relative distance only impacts the displacement values of tunnel, but not the influenced range of tunnel. It may provide certain reference to analyze the deflection of subway tunnel influenced by adjacent excavation.展开更多
Middle East and North Africa （MENA） has been experiencing a unique demographic transition in the world especially after September 11, whilst, its social, political and economic structures have considerably remained ...Middle East and North Africa （MENA） has been experiencing a unique demographic transition in the world especially after September 11, whilst, its social, political and economic structures have considerably remained inflexible and can hardly meet the increasing demands of employment among the youth whose expectations are raised through expansion in education. In spite of various common causes for the Arab uprisings, the paper spotlights the ＂Youth role＂ and its regarded issues of ＂Youth Bulge＂, ＂Education＂ and ＂Unemployment＂ with a glimpse to the overturned regimes of ＂Tunisia, Egypt, Libya, and Yemen＂. According to published statistics these countries are among the countries with the highest rate of youth as working age population in MENA. Therefore, the paper is to present the importance and impact of youth as a social parameter in challenging political structure of the countries in the MENA and leading to topple their political systems. Thus, the paper reasons the MENA political upheavals, in general, and the mentioned countries＇ uprisings, in particular, can not be well understood disregarding to natural tensions between economic, population structures, and political demographic challenges. This is to be done drawing on data from different international institutions. The intervened variables such as ＂ethnicity, race, religion and sexuality＂ and international parameters have not been considered.展开更多
Introduction,A better understanding the functioning of Earth System in the context of past climatic upheavals is essential for predictions about the fate of the diversity of life and the future of our society.The Inte...Introduction,A better understanding the functioning of Earth System in the context of past climatic upheavals is essential for predictions about the fate of the diversity of life and the future of our society.The International Geoscience Program(IGCP),a joint initiative of UNESCO and IUGS,serves as a knowledge hub to facilitate international scientific cooperation in the geosciences.One of the strategical themes of the IGCP is Global Change:evidence from the geological record,which perfectly applies to the project IGCP-655,Toarcian Oceanic Anoxic Event:Impact on marine carbon cycle and ecosystems.展开更多
The political upheavals in the Arab world during 2011 challenged the political status quo and have irrevocably paved the way toward transformation in the Middle East and North Africa （MENA）, The longstanding structu...The political upheavals in the Arab world during 2011 challenged the political status quo and have irrevocably paved the way toward transformation in the Middle East and North Africa （MENA）, The longstanding structural impediments to equitable growth and social justice afflicting the Arab world came to a head through a combination of persistently poverty, high unemployment, particularly among educated youth, rampant corruption, deficit of democratic governance, and essential freedoms. Yemen is the third country of the Middle Eastern countries which turmoil sparked in. All the uprisings connote of social, political and economic discontent and frustration. The main question and issue of this paper is to answer： What conditions breed change to Yemen？ The paper spotlights ＂relative deprivation＂ of Ted Robert Gurr as the most relevant theory to illustrate roots of the Yemen uprising. Relative deprivation theory holds that instead of an absolute standard deprivation, a gap between expectations and reality leads men to political violence. Therefore, this study is to utilize relative deprivation theory to explain how socio-economic shortages （such as high unemployment and education, along with poverty） and political inefficiencies of the Yemen＇s authoritarian regime led to public and collective discontent and upheaval. The intervened variables such as ＂ethnicity, race, religion, and sexuality＂ and international parameters have not been considered,展开更多
King Lear, as one of Shakespeare's the most critical tragedies has long been discussed since it was published, because of the ethnic and social moral problems that King Lear has revealed. And these problems that S...King Lear, as one of Shakespeare's the most critical tragedies has long been discussed since it was published, because of the ethnic and social moral problems that King Lear has revealed. And these problems that Shakespeare has given to us through the play King Learare never limited by the ages and nations, they are general social problems. This paper aims at analyzing the major character and the reason that causes this tragic ending. King Lear can be regarded as the mirror to the society by describing the tragedy of the two families in the play, the King Lear's family and the Glouster's family. Shakespeare has also denounced the social phenomenon that some children are not moral to their parents under the attraction of power and wealth by depicting the ideal and perfect figure Cordelia, it invokes us that it is necessary to build a society which is filled with love and happiness.展开更多
Many marine ecosystems are under threat at the present day.The geological record provides numerous analogues of environmental upheavals and major biocrises,the most disruptive of which occurred during the Permian-Tria...Many marine ecosystems are under threat at the present day.The geological record provides numerous analogues of environmental upheavals and major biocrises,the most disruptive of which occurred during the Permian-Triassic(P-Tr)transition at~252 million years ago.Many of the factors that contributed to the P-Tr biotic crisis,e.g.,increased atmospheric carbon dioxide concentrations,rapid global warming,oceanic anoxia,and hypercapnia(CO_(2) poisoning)are also observed in the present day or are anticipated to develop in the near future.The Permian-Triassic transition may thus record a natural experiment in globalscale ecosystem collapse that,if properly deciphered,could provide important insights into possible responses of modern marine ecosystems to present day climate and environmental change.展开更多
基金Project(51021004) supported by Innovative Research Groups of the National Natural Science Foundation of ChinaProject(40776055) supported by the National Natural Science Foundation of china+1 种基金Project(1002) supported by State Key Laboratory of Ocean Engineering Foundation, ChinaProject(NCET 11 0370) supported by the Program for New Century Excellent Talents in Universities of China
文摘In-service hydrocarbons must be transported at high temperature and high pressure to ease the flow and prevent the solidification of the wax fraction. The pipeline containing hot oil will expand longitudinally due to the rise in temperature. If such expansion is resisted, for example by frictional effects over a kilometer or so of pipeline, compressive axial stress will be built up in the pipe-wall. The compressive forces are often so large that they induce vertical buckling of buffed pipelines, which can jeopardize the structural integrity of the pipeline. A typical initial imperfection named continuous support mode of submarine pipeline was studied. Based on this type of initial imperfection, the analytical solution of vertical thermal buckling was introduced and an elastic-plasticity finite element analysis （FEA） was developed. Both the analytical and the finite element methodology were applied to analyze a practice in Bohai Gulf, China. The analyzing results show that upheaval buckling is most likely to build up from the initial imperfection of the pipeline and the buckling temperature depends on the amplitude of initial imperfection. With the same amplitude of initial imperfection, the triggering temperature difference of upheaval buckling increases with covered depth of the pipeline, the soil strength and the friction between the pipeline and subsoil.
基金Supported by National Natural Science Foundation of China (No.40776055)
文摘In this paper,a theoretical solution of vertical buckling is proposed with regard to the typical initial imperfection cases of submarine pipelines.Analytical tools are applied to predicting the occurrence and consequence of inservice buckling of a buried heated pipeline in Bohai Gulf.An evaluation is performed to ensure the pipeline structural integrity during operation under loading conditions.Different protection measures are proposed and their validities are analyzed.Analyses show that for the same magnitude of initial imperfection,the upheaval buckling of pipeline with isolated prop model is the most likely to occur.The empathetic model represents a special sub-case of continuous prop model,and the calculated buckle temperature is between the first stage and the second stage of post-upheaval buckling of continuous prop model.And the larger the initial imperfection,the less the axial force required for the upheaval buckling.Meanwhile,it can be seen that a peak point appears on the curves of temperature difference against buckling amplitude for small initial imperfection.Besides,trenching-burial is one kind of protection measures preventing the pipeline from thermal upheaval.The covered depth-to-diameter ratio depends on the design conditions and subsoil properties.For the given pipeline in this paper,the covered depth-to-diameter ratio is recommended to be 5.
基金Project supported by the Foundation for Innovative Research Groups of the National Natural Science Foundation of China (No.51021004)the National Natural Science Foundation of China(No.40776055)the Foundation of the State Key Laborary of Ocean Engineering (No.1002)
文摘In-service hydrocarbons must be transported at high temperature and high pressure to ease the flow and to prevent the solidification of the wax fraction. The high temperature and high pressure will induce the additional stress in the pipeline, which results in the upheaval buckling of the pipeline. If such expansion is resisted, e.g., by the frictional effects of the foundation soil over a kilometer or of a pipeline, the compressive axial stress will be set up in the pipe-wall. When the stress exceeds the constraint of the foundation soil on the pipeline, suddenly-deforming will occur to release the internal stress, similar to the sudden deformation of the strut due to stability problems. The upheaval buckling may jeopardize the structural integrity of the pipeline. Therefore, effective engineering measures against this phenomenon play an important role in the submarine pipeline design. In terms of the pipeline installation and protection measures commonly used in Bohai Gulf, three engineering measures are investigated in great details. An analytical method is introduced and developed to consider the protection effect of the anti-upheaval buckling of the pipeline. The analysis results show that the amplitude of the initial imperfection has a great effect on the pipeline thermal upheaval buckling. Both trenching and burial and discrete dumping are effective techniques in preventing the pipeline from buckling. The initial imperfection and operation conditions of the pipelines determine the covered depth and the number of layers of the protection measures.
文摘Damming landslides are very common in China, they ever blocked the rivers and streams completely or partly, and form natural lakes. Now more than 150 damming landslides in China are recognized through field investigation and data collection indoors. These Landslides distribute in steep mountainous counties around the Qinghai—Tibet Plateau, and mainly of which in southwest China and northwest China.. Studies show that the distribution of damming landslides has a close relation with the event of the Tibet plateau upheaval. The thermodynamic effect on the free atmosphere results from rapid upheaval of Qinghai\|Tibet plateau is more and more intensive, it causes air to circulate from east to west. In winter, the high Tibet Plateau leads the cool air gather quickly and high cool potential to be stronger. On one side, an anticyclone cool high pressure forms near the ground surface at the altitude of 4000～5000m, and produces winter monsoon wind. On the other side, the shielding effect of the plateau impedes the air from Siberia touching with the air from south Indian Ocean, which causes the cool air from Siberia enters China frequently and strengthens the cool and drought in northwest China. In summer, the monsoon wind is impeded by the plateau and cannot enter into north China, where it is dry, it can only moves around the plateau and at the edge enters into southwest, south, middle and east China, where the rainfall process is strong. Thus south and east of the plateau become the areas with many damming landslides resulted from heavy rain.
基金Project supported by the National Natural Science Foundation of China(Nos.51988101 and 51178427)the Natural Science Foundation of Zhejiang Province(No.LCZ19E080002)the Fundamental Research Funds for the Central Universities(No.2019FZA4016),China。
文摘Upheaval buckling of pipelines can occur under thermal expansion and differential ground settlement.Research on this phenomenon has usually assumed the pipes are buried in horizontal ground.For long-distance transmission pipelines across mountainous areas,the ground surface is commonly inclined.Based on the Rankine earth pressure theory and Mohr-Coulomb failure criterion,analytical formulae for calculating the peak uplift resistance and the slip surface angles for a buried pipe in inclined ground are presented in this paper.Analyses indicate that the slip surfaces in inclined ground are asymmetric and rotate towards the downhill side.Under a shallow burial depth,the failure plane angle is highly impacted by the ground inclination.When the embedment ratio(H/D)is more than 4,the influence of the ground slope on the failure plane angle is negligible.The peak uplift resistance reduces in inclined ground,especially when H/D is less than 1.Finally,a simple equation considering the impact of ground inclination is proposed to predict the peak uplift resistance.
文摘From April 14 to 18,Chinese President Xi Jinping made state visits to Vietnam,Malaysia,and Cambodia.This tour coincided with global upheaval caused by“reciprocal tariffs”imposed by U.S.President Donald Trump,which turned global eyes towards China and Southeast Asian nations to see how they would strengthen cooperation and respond to the“Trump effect.”
基金supported by grants from the Research Grant Council of the Hong Kong Special Administrative Region,China(Project No.HKU 17207518).
文摘This paper presents a dynamic modeling method to test and examine the minimum mass of pressurized pore-gas for triggering landslides in stable gentle soil slopes.A stable gentle soil slope model is constructed with a dry cement powder core,a saturated clay middle layer,and a dry sand upper layer.The test injects H_(2)O_(2)solution into the cement core to produce new pore-gas.The model test includes three identical H_(2)O_(2)injections.The small mass of generated oxygen gas(0.07%of slope soil mass and landslide body)from the first injection can build sufficient pore-gas pressure to cause soil upheaval and slide.Meanwhile,despite the first injection causing leak paths in the clay layer,the generated small mass of gas from the second and third injections can further trigger the landslide.A dynamic theoretical analysis of the slope failure is carried out and the required minimum pore-gas pressure for the landslide is calculated.The mass and pressure of generated gas in the model test are also estimated based on the calibration test for oxygen generation from H_(2)O_(2)solution in cement powder.The results indicate that the minimum mass of the generated gas for triggering the landslide is 2 ppm to 0.07%of the landslide body.Furthermore,the small mass of gas can provide sufficient pressure to cause soil upheaval and soil sliding in dynamic analysis.
基金supported by National Natural Science Foundation of China (Grant No.40872138)Science and Technology Research Key Project of Ministry of Education (Grant No.107042)Excellent Academic Leaders Program of Shanghai (Grant No.08XD14042)
文摘Fission-track, (U-Th)/He thermochronology, and cooling properties indicate that the southern Daba arcuate zone (SDBAZ) underwent a distinctive phase of rapid cooling in 153-100 Ma at a rate of 1.44-1.90°C/Ma. This rapid uplifting strongly contrasts with (1) the previous, rapid foreland subsidence during Early to Middle Jurassic in response to late-orogenic compression from the Qinling belt, (2) the succeeding long, slow cooling phase and relative thermal stability that occurred during the 100-45 Ma period. This rapid cooling event in the SDBAZ parallels those experienced by two adjacent upheavals of Huangling (HLUZ) and Hannan-Micang (HMUZ), with cooling rates of 2.22-3.17°C/Ma for the HLUZ in 160-126 Ma, 4.91°C/Ma for the southern HMUZ in 150-125 Ma, as well as 2.11°C/Ma for the northern HMUZ in 150-105 Ma. Comparing thermal histories among the SDBAZ, the HLUZ, the HMUZ, and the Wudang metamorphic zone (WDMZ), we infer that the Daba arcuate structural belt formed in 153-100 Ma. The combined dating data support a correlation with a low-angle arcuate south-thrusting of the Qinling orogen triggered by northward convergence of the Yangtze Craton, contemporaneously encountering rigid basement obstructions from the HLUZ and the HMUZ, respectively. Both the SDBAZ and neighboring domains additionally underwent a comparatively fast cooling and uplift since about 45 Ma.
文摘The fundamental motivation leading to the Middle East Upheaval is an urgent need for the internal political and social transformation in Middle East countries.International public opinion,particularly the Western discourse that occupies a stronger position has had a profound impact on the development of the whole situation.With China’s continued rise,there is an increase in its competitions and frictions with the United States and other Western powers in global political,economic and other areas.The West uses its advantages in controlling international public opinion,and continues to manufacture discourse and set agendas and even slander regarding Chinese policies.This is not only to guide the situation,but more to maintain its dominant position in international affairs and to contain China’s rising influence.In recent years,China has taken a more aggressive Middle East policy.However,its ability to construct discourse and set agendas is relatively lacking.Therefore,China often remains passive and reactive when responding to the traps set in the Western discourse and agendas.This article focuses on the international competition for discourse power in the Middle East upheaval and the implications for china.
文摘Arab countries have been faced with a large scale Middle Eastern upheaval,which has attracted the attention of all the Middle Eastern countries and international community.The current situation is primarily related to the important location of the Middle East.Nearly all the Arab countries are involved in the upheaval.Omnifarious appeals are claimed by the people,including political,economic and social aspects.The problems have been accumulating for years,and the Middle East upheaval in 2011 was an overall outburst of people’s dissatisfaction.The cost of the unrest is high despite the social progress it may promote.At present,a fragile peace is realized in Syria though the prospect of future development is unclear.Since the outbreak of the Middle East upheaval,China has adopted a principle of“non-intervention in other’s internal affairs”and“mediating for peace while promoting talks”policy,which is appropriate and proactive.China should adhere to this practice in the future despite the voices of opposition and temporary misunderstanding.
文摘Due to more than one-year’s upheaval,many Middle Eastern countries experienced regime change,and Syria is the next target and center of this political swirl.The rise of Islamic force is a serious problem for these countries in transition to deal with.Because of this upheaval,the Middle Eastern configuration is facing challenges;the contradiction within regional powers is experiencing growth and decline.The adjustment of America’s Middle East policy has affected the trend of Middle East situation.China’s“non-interference in others’internal affairs”principle gains international society’s interpretation,and China’s diplomacy towards the Middle East is facing important opportunity and enormous challenges.China should seize the opportunity and seek the new development of China-Middle East relations.
基金the“Islamic Factors in Contemporary International Relations of the Middle East Studies”project in 2008 supported by the MOE Project of Key Research Institute of Humanities and Social Sciences in Universities(08JJDGJW256)Shanghai Philosophy and Social Science project“Theory and Case Study of Chinese Diplomacy”(2010BGJ002)in 2010It is also supported by the Shanghai Project of First Class Disciplines:Political Science.
文摘Prior to the Middle East upheavals,democratic transitions in Arab countries could be roughly divided into three stages,namely,the early constitutional reform,the third wave of democratization and democratic reforms under the impact of the end of the Cold War,and during the democratization process under pressure from the US“Greater Middle East”initiative in the new century.The Middle East upheavals are part of political and social movements that involve the whole Arab world.They have not only some common features,but also huge differences;the long-standing problems in Arab countries in the political,economic and social areas are the fundamental causes of Middle East upheavals.However,in addition to this,they are also affected by the US“Greater Middle East”initiative and other external factors.Democratic reforms and transitions undoubtedly constitute an important part of the Middle East upheavals.Arab countries are currently carrying out democratic reforms,but meanwhile they are also facing many challenges.The core elements that affect the progress of democratic transitions include three factors:Islam,military intervention and geopolitical factors.With respect to the relationship between Islam and democratic transition,the conflicts between religious and secular forces will continue to have an impact on the democratic transition of the Arab countries.0n the other hand,moderate Islamic forces will explore democratization with Islamic characteristics.The relationship between Islam and democracy will be developing in diversified ways,and consecutively adjusting and remodeling.In terms of relationship between military intervention and the democratic transition,there will be a long way to eliminate the impact of military intervention in Arab countries,and a long process from the starting of democracy to democratic consolidation,and eventually to democratic functioning.This also depends on the normalization of relations between religious and secular forces after a long period of interaction and accommodation.On the relationship between geopolitics and democratic transition,complicated internal religious,sectarian and ethnic conflicts,contradictions among Arab countries,ideological competition and regional leadership competition,as well as the military intervention and exports of democracy from Western powers,have exacerbated the turbulence in the Arab democratic transition.
基金support provided by the National Natural Science Foundation of China(Grant No.42077235)the Science and Technology Plan Project of Xuzhou,China(Grant No.KC21310)the Open Fund of the State Key Laboratory for Geomechanics and Deep Underground Engineering(Grant No.SKLGDUEK 1902).
文摘Reliable assessment of uplift capacity of buried pipelines against upheaval buckling requires a valid failure mechanism and a reliable real-time monitoring technique.This paper presents a sensing solution for evaluating uplift capacity of pipelines buried in sand using fiber optic strain sensing(FOSS)nerves.Upward pipe-soil interaction(PSI)was investigated through a series of scaled tests,in which the FOSS and image analysis techniques were used to capture the failure patterns.The published prediction models were evaluated and modified according to observations in the present study as well as a database of 41 pipe loading tests assembled from the literature.Axial strain measurements of FOSS nerves horizontally installed above the pipeline were correlated with the failure behavior of the overlying soil.The test results indicate that the previous analytical models could be further improved regarding their estimations in the failure geometry and mobilization distance at the peak uplift resistance.For typical slip plane failure forms,inclined shear bands star from the pipe shoulder,instead of the springline,and have not yet reached the ground surface at the peak resistance.The vertical inclination of curved shear bands decreases with increasing uplift displacements at the post-peak periods.At large displacements,the upward movement is confined to the deeper ground,and the slip plane failure progressively changes to the flow-around.The feasibility of FOSS in pipe uplift resistance prediction was validated through the comparison with image analyses.In addition,the shear band locations can be identified using fiber optic strain measurements.Finally,the advantages and limits of the FOSS system are discussed in terms of different levels in upward PSI assessment,including failure identification,location,and quantification.
基金supported by the Innovative Research Groups of the National Natural Science Foundation of China (GrantNo. 51021004)the National Natural Science Foundation of China (Grant No. 40776055)the State Key Laboratory of OceanEngineering Foundation (Grant No. 1002)
文摘The buckling of submarine pipelines may occur due to the action of axial soil frictional force caused by relative movement of soil and pipeline, which is induced by the thermal and internal pressure. The likelihood of occurrence of this buckling phenomenon is largely determined by soil resistance. A series of large-scale model tests were carried out to facilitate the establishment of substantial data base for a variety of burial pipeline relationships. Based on the test data, nonlinear soil spring can be adopted to simulate the soil behavior during the pipeline movement. For uplift resistance, an ideal elasticity plasticity model is recommended in the case of H/D （depth-to-diameter ratio）〉5 and an elasticity softened model is recommended in the case of H/D≤5. The soil resistance along the pipeline axial direction can be simulated by an ideal elasticity plasticity model. The numerical analyzing results show that the capacity of pipeline against thermal buckling decreases with its initial imperfection enlargement and increases with the burial depth enhancement.
基金supported by the Fundamental Research for the Central Universities (SWJTU11ZT33)the Funds for the development of Innovation team of Ministry of Education (IRT0955)
文摘Predicting and estimating the response of sub- way tunnel to adjacent excavation of foundation pit is a research focus in the field of underground engineering. Based on the principle of two-stage method and incre- mental method, an analytic approach is suggested in this paper to solve this problem in an accurate and rapid way, and the upheavals of tunnel due to adjacent excavation are solved by analytic method. Besides, the presented method is used in the practical engineering case of Shenzhen Metro Line 11 and verified by numerical simulation and in situ measurement. Finally, a parametric analysis is performed to investigate the influence of different factors on tunnel＇s deflection. Some useful conclusions have been drawn from the research as below： The deflection results of tunnel obtained from analytic method are nearly consistent with the results getting from numerical analysis and measured data, which verified the accuracy and rationality of pre- sented method. The excavation size has a significant impact on both the displacement values and influenced range of tunnel. However, the relative distance only impacts the displacement values of tunnel, but not the influenced range of tunnel. It may provide certain reference to analyze the deflection of subway tunnel influenced by adjacent excavation.
文摘Middle East and North Africa （MENA） has been experiencing a unique demographic transition in the world especially after September 11, whilst, its social, political and economic structures have considerably remained inflexible and can hardly meet the increasing demands of employment among the youth whose expectations are raised through expansion in education. In spite of various common causes for the Arab uprisings, the paper spotlights the ＂Youth role＂ and its regarded issues of ＂Youth Bulge＂, ＂Education＂ and ＂Unemployment＂ with a glimpse to the overturned regimes of ＂Tunisia, Egypt, Libya, and Yemen＂. According to published statistics these countries are among the countries with the highest rate of youth as working age population in MENA. Therefore, the paper is to present the importance and impact of youth as a social parameter in challenging political structure of the countries in the MENA and leading to topple their political systems. Thus, the paper reasons the MENA political upheavals, in general, and the mentioned countries＇ uprisings, in particular, can not be well understood disregarding to natural tensions between economic, population structures, and political demographic challenges. This is to be done drawing on data from different international institutions. The intervened variables such as ＂ethnicity, race, religion and sexuality＂ and international parameters have not been considered.
文摘Introduction,A better understanding the functioning of Earth System in the context of past climatic upheavals is essential for predictions about the fate of the diversity of life and the future of our society.The International Geoscience Program(IGCP),a joint initiative of UNESCO and IUGS,serves as a knowledge hub to facilitate international scientific cooperation in the geosciences.One of the strategical themes of the IGCP is Global Change:evidence from the geological record,which perfectly applies to the project IGCP-655,Toarcian Oceanic Anoxic Event:Impact on marine carbon cycle and ecosystems.
文摘The political upheavals in the Arab world during 2011 challenged the political status quo and have irrevocably paved the way toward transformation in the Middle East and North Africa （MENA）, The longstanding structural impediments to equitable growth and social justice afflicting the Arab world came to a head through a combination of persistently poverty, high unemployment, particularly among educated youth, rampant corruption, deficit of democratic governance, and essential freedoms. Yemen is the third country of the Middle Eastern countries which turmoil sparked in. All the uprisings connote of social, political and economic discontent and frustration. The main question and issue of this paper is to answer： What conditions breed change to Yemen？ The paper spotlights ＂relative deprivation＂ of Ted Robert Gurr as the most relevant theory to illustrate roots of the Yemen uprising. Relative deprivation theory holds that instead of an absolute standard deprivation, a gap between expectations and reality leads men to political violence. Therefore, this study is to utilize relative deprivation theory to explain how socio-economic shortages （such as high unemployment and education, along with poverty） and political inefficiencies of the Yemen＇s authoritarian regime led to public and collective discontent and upheaval. The intervened variables such as ＂ethnicity, race, religion, and sexuality＂ and international parameters have not been considered,
文摘King Lear, as one of Shakespeare's the most critical tragedies has long been discussed since it was published, because of the ethnic and social moral problems that King Lear has revealed. And these problems that Shakespeare has given to us through the play King Learare never limited by the ages and nations, they are general social problems. This paper aims at analyzing the major character and the reason that causes this tragic ending. King Lear can be regarded as the mirror to the society by describing the tragedy of the two families in the play, the King Lear's family and the Glouster's family. Shakespeare has also denounced the social phenomenon that some children are not moral to their parents under the attraction of power and wealth by depicting the ideal and perfect figure Cordelia, it invokes us that it is necessary to build a society which is filled with love and happiness.
文摘Many marine ecosystems are under threat at the present day.The geological record provides numerous analogues of environmental upheavals and major biocrises,the most disruptive of which occurred during the Permian-Triassic(P-Tr)transition at~252 million years ago.Many of the factors that contributed to the P-Tr biotic crisis,e.g.,increased atmospheric carbon dioxide concentrations,rapid global warming,oceanic anoxia,and hypercapnia(CO_(2) poisoning)are also observed in the present day or are anticipated to develop in the near future.The Permian-Triassic transition may thus record a natural experiment in globalscale ecosystem collapse that,if properly deciphered,could provide important insights into possible responses of modern marine ecosystems to present day climate and environmental change.
