28 July 2013, Volume 31 Issue 21

    

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  Design Method of Ventilation and Smoke Exhaustion Against Urban Traffic Link Tunnel Fire

  JIANG Xuepeng;FU Weigang;YUAN Yueming;LI Xu;WANG Wei

  . 2013, 31(21): 15-20. https://doi.org/10.3981/j.issn.1000-7857.2013.21.001

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  The Urban Traffic Link Tunnel (UTLT) is a new type of underground transportation, with quite a few entrances to underground garages. It is more complicated to design the ventilation and smoke exhaustion for the UTLT than for a general urban straight tunnel. According to the structural features of the UTLT, the design method of ventilation and smoke exhaustion against UTLT fire is presented. The UTLT is regarded as an independent structure apart from adjacent underground garages in cases of fire. According to the layout of the ventilation shafts and the ground access, the UTLT is divided into multiple smoke control sections by the fire roller shutters. The fire smoke flows out of the ground following the travel direction in the limited smoke control zones. An UTLT is taken as an example, with eight sections and three smoke exhaust patterns. The smoke control effect of typical fire scenarios is simulated by FLUENT. The results show that the smoke is limited to the flow in the setting smoke control sections and can be exhausted out of the tunnel. And there is no back-layering flow of hot smoke, which can satisfy UTLT ventilation requirements and ensure the safe escape for people in the upstream of the fire and the vehicles in the downstream. So the design method of ventilation and smoke exhaustion against the UTLT fire is reasonable. The research results can be applied directly to the design of ventilation and smoke exhaustion for UTLTs.
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  Dynamic Analysis of Rigid Pavement Under Variable Velocity Moving Loads

  YANG Lifeng

  . 2013, 31(21): 21-25. https://doi.org/10.3981/j.issn.1000-7857.2013.21.002

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  In this paper, the rigid roadway pavement under dynamic traffic loads with variable velocity is studied. The rigid roadway pavement is modeled as a rectangular damped orthotropic plate supported by elastic Pasternak foundation. The boundaries of the plate are the steel dowels and tie bars which provide the elastic vertical support and the rotational restraint. The natural frequencies and the modal shapes of the system are obtained through solving two transcendental equations, derived from the solution of two auxiliary Levy's type problems, known as the Modified Bolotin Method. The dynamic moving traffic load is expressed as a concentrated load of harmonically varying magnitude, moving straight along the plate with a variable velocity. The dynamic response of the plate is obtained by using the characteristic equation with orthogonal properties. The results of a numerical example show that the velocity and the angular frequency of the loads affect the maximum dynamic deflection of the rigid roadway pavement. It is also shown that a critical speed of the load exists. If the moving traffic load travels at the critical speed, the rectangular plate will suffer from a deflection of infinite amplitude. The present mathematical solution should be verified further with the results of experimental researches, especially, with respect to the determination of the forces in the steel connecting devices (dowels and tie bars) along the joints.
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  Reliability Analysis of Civil Systems Engineering Based on Mixed Logit Model

  CAO Yi;WEI Lianyu;MA Shibin;YU Huan

  . 2013, 31(21): 26-29. https://doi.org/10.3981/j.issn.1000-7857.2013.21.003

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  The mixed Logit model is used to study the reliability of the civil systems engineering in combination with the civil engineering and the systems engineering. The SPSS software is used to make the statistical and reliability analyses of the survey data, and the key indicators that affect the reliability of the civil systems engineering are obtained. In the meanwhile, an appropriate mixed Logit model is established, and the multivariate statistical analysis software SAS is used for simulation and reliability analyses with respect to the three typical modes of civil systems engineering-DBB, PMC, and EPC. It is shown that the reliability index of DBB mode is 83.69%, while those of the PMC model and the EPC mode are 76.03% and 71.39%, which indicates that that DBB mode has the highest reliability. The results and the method provide a theoretical basis for the applications of the civil systems engineering modes.
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  DEM Contrastive Analysis of Spherical Motion in Inclined Plane

  YAN Min;QI Chao

  . 2013, 31(21): 30-33. https://doi.org/10.3981/j.issn.1000-7857.2013.21.004

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  Based on previous research, an innovative method to investigate object dynamics is suggested. Concerning DEM itself, it can precisely simulate the interaction among discrete spheres. DEM is a powerful tool in simulation and calculation. One sphere is kinetic in an inclined plane with 45°. After reasoning theoretical formula and establishing theoretical model by which theoretical relations between velocity-time and displacement-time are acquired respectively, DEM is employed and visual sphere-inclined plane is archived in the platform of Borland C++ 6.0, then, the theoretical formula is deduced. and the theoretical curves are drawn. Also, critical coefficient of friction will be determined when sphere is purely rolling in an inclined plane. The relationship of velocity-time and displacement-time will be achieved respectively when sphere moves on pure displacement condition, sliding and rolling condition, and purely rolling condition, then their relational curves are drawn. These curves are compared to theoretical curves of the relationship between velocity-time, and the relationship between displacement-time. It is concluded that computed results and theoretical results are consistent. Therefore, it is verified that theory of DEM is available.
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  Chain Model and Engineering Application of Water Disaster in Underground Mining

  HU Jianhua;HE Chuan;DENG Hongwei;LIN Yangfan

  . 2013, 31(21): 34-38. https://doi.org/10.3981/j.issn.1000-7857.2013.21.005

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  Chain effect of water disaster has been found during the mining process in the underground mining. Taken disaster chain theory and characteristics of the mine into account, the chain-cutting disaster mitigation model and engineering measures are great significant to the underground mine. According to the theory model of disaster chain, the water disaster chain model of a mine in Hunan was built. Elements in water disaster chain model was divided into three collections. The relations among elements in water disaster chain were built as equations. The characteristics of elements changing over times were analyzed. Three approaches of disaster mitigations were proposed for each period of water disaster chain. The 610 level's mine water trouble of the mine in Hunan was taken as an engineer example, the results showed that, the built mine water disaster chain model could effectively describe the characters of mine water disasters. This mine water disaster chain source was mainly formed by the surface water seep and the water storage in goaf. The disaster output was transformed from the chain source through water-conducting induce under the response of mining. The 610 level's water trouble was in the period of disaster burst. Engineering measures were raised to deal with chain-cutting disaster mitigation, control of water disaster and water resources utilization coordinately, such as filling mined-out area, underground drainage and circulation utilization of water resources.
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  Evaluation of Coal Seam Stability Based on Fuzzy Pattern Recognition

  HUO Bingjie;ZHANG Hongwei;GUO Sicong

  . 2013, 31(21): 39-43. https://doi.org/10.3981/j.issn.1000-7857.2013.21.006

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  The comprehensive quantitative evaluation methods for different kinds of coal seam stability based on the fuzzy pattern recognition theory are studied in this paper. The coal seam stability evaluation using the fuzzy pattern recognition method is proposed, with an analysis of the key factors affecting the coal seam stability, to determine the characteristics of the coal seam stability evaluation factors, and to build the fuzzy evaluation for different types of coal seam in language patterns and their membership functions. To verify the feasibility of the method, an example is taken for the evaluation. The results show that the method can realize the quantitative partition for the stability of the coal seam type and belonging, can provide the basis for the coal seam mineable analysis, the mining safety evaluation, and the mining method choice.
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  Numerical Simulation of Flow Field for Organ-pipe Cavitation Jet Nozzle

  HU Kun;AI Zhijiu;FU Biwei;JIA Lin;PENG Xu

  . 2013, 31(21): 44-47. https://doi.org/10.3981/j.issn.1000-7857.2013.21.007

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  Organ-pipe cavitation jet nozzle is a common nozzle for cavitation jet, by using its internal special structure; the nozzle generates the cavitation effect in order to improve the percussion effect of jet. Therefore, the research on the structure inside of cavitation nozzle is able improve the nozzle performance. By using multi-phase flow model to study organ-pipe cavitation nozzle, on the conditions of the outlet pressure of 2MPa, for the different inlet pressure, nozzle inner flow field is numerically calculated. The results indicate that with the normal working pressure of 8MPa, nozzle throat position locates at local low speed zone and low pressure area, and cavitation position appears at the position of throat section mutation. At the same time, in the case of the nozzle throat long diameter ratio and existing corner, the internal cavitation is studied; the following conclusions are drawn: The increase of nozzle throat long diameter larger than it is actually is equivalent to increase the low pressure area, and is helpful for the generation of cavitation; that nozzle throat reducer area exists corner would seriously affect the cavitation performance of cavitation nozzle, and the larger radius is, the bigger the critical cavitation pressure is.
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  Quantitative Analysis of Oil Coring Project Risk

  CHENG Yuanfang;WU Lingyan;CUI Qing;XU Junliang;DONG Bingxiang

  . 2013, 31(21): 48-52. https://doi.org/10.3981/j.issn.1000-7857.2013.21.008

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  Risk prediction and analysis is essential for risk control because of the uncertainty of coring project. Combined with the characteristics of coring project, the risk factors and events were recognized and analyzed effectively; the risk assessment system and mathematic model were established. Using Monte Carlo simulation method as well as AHP, the risk of coring project could be analyzed and calculated. With the consideration of various uncertainly risk factors, combination sampling method was applied to get a quantized risk probability distribution. Meanwhile, according to the simulation results, the risk index of each factor was available which quantized its corresponding contribution to the risk of the project. Then, the risk factors or events with high index could be found based on the analysis of probability, which is helpful in risk management of coring project and promoted the success ratio and recovered the rate of coring. This risk analysis method covered a variety of possibilities and delivered the uncertainties of parameters; its counting process reduced the loss of information, then the result is more accurate. Meanwhile, the sensitivity analysis could be carried on the base of data samples for deeper insight. On one hand, this study established a new evaluation methodology and supplied decision basis for the risk analysis and management of hydrate coring project; on the other hand, it made the foundational research work for subsequent more perfect hydrate coring project evaluation. Research showed that this method can achieve a good evaluation effectiveness and its prediction results are reasonable and practicable.
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  Transient Pressure Analysis of Partial Open Fractured Wells in Shale Gas Reservoirs

  REN Junjie;GUO Ping;HU Yongqiang;WANG Delong

  . 2013, 31(21): 53-57. https://doi.org/10.3981/j.issn.1000-7857.2013.21.009

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  Fractured wells find widespread applications in the development process of shale gas reservoirs because of the enhancement of the per well production and the reduction of the cost. However, the reservoir is difficult to be completely opened in practice because of the large thickness of the shale gas reservoir. In this paper, according to the characteristics of desorption, diffusion and seepage, a seepage model of partial open fractured wells in shale gas reservoirs is established. The Laplace transform, the Fourier transform and the principle of Duhamel in combination with the Stehfest numerical inversion algorithm are used to obtain solutions based on the model. The pressure characteristic curves are obtained. The flowing phases are divided in the pressure characteristic curves. The influence of the relevant parameters on the pressure dynamic characteristics is analyzed. It is shown that there are seven main flow stages in the pressure characteristic curves for partial open fractured wells in shale gas reservoirs. The open degree has a main effect on the appearance of the spherical flow period and the position of the pressure derivative curve in the early time. The desorption coefficient has a primary effect on the depth of the dip in the pressure derivative curve. The dimensionless storativity ratio has a major effect on the depth and width of the dip in the pressure derivative curve. The dimensionless transmissivity ratio has a primary effect on the starting time of the desorption and the diffusion in shale reservoirs. The results can provide a theoretical support for the high-efficiency development of shale gas reservoirs using fractured wells.
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  Seismic Random Noise Suppression by Using Frequency-domain Singular Value Decomposition

  BAO Wei;MA Jitao

  . 2013, 31(21): 58-63. https://doi.org/10.3981/j.issn.1000-7857.2013.21.010

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  Singular Value Decomposition (SVD) is a new and effective method for random noise suppression. The principle of the SVD filtering technique, which enhances the signal to noise ratio of seismic data, is illustrated. Then, by applying time-domain and frequency- domain SVD techniques to suppress random noise generated from a variety of seismic model data, their processing results are compared with each other. The results indicate that the time-domain SVD technique is only able to enhance flat or near flat events. Whenencountering dip events, it is less effective. However, the frequency-domain SVD technique is able to enhance both flat and dip events, and improve the signal to noise ratio of seismic profile. Three simple synthetic seismograms and one real seismic data are used, and the practical effects of these two SVD methods are verified. The results show that the frequency-domain SVD is effective for suppressing the random noise.
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  Measurement of the Convergence of Science and Its Policy Implication

  SUN Mengxin;LUAN Chunjuan

  . 2013, 31(21): 64-68. https://doi.org/10.3981/j.issn.1000-7857.2013.21.011

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  The convergence of science is a natural tendency and a sure choice for the development of science worldwide in the 21st century. Taking as examples the climate-related literature in the data banks of both SCI and SSCI, and applying the newly-emerged visualized information software and technical means, the paper obtains visualized subject-specific maps of knowledge domains, which may be used to analyze the development trend of disciplines in the evolution of the converging science. As indicated by the analysis, the subject distribution of global climate researches covers many disciplines including the natural sciences, the social sciences, the humanities, and other cross-cutting subjects. The number of climate-related papers increases sharply, and the number of subjects is also in gradual increase. The research results would be remarkably indicative to the allocation of S&T human resources and the fostering of talents in higher-learning institutions in China. Some further and in-depth studies are required in the micro level.
Reviews
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  Progresses of the Application of Talcum Powder in Water Treatment

  LI Ping;LI Sifan;YANG Shuangchun;MA Biao

  . 2013, 31(21): 69-73. https://doi.org/10.3981/j.issn.1000-7857.2013.21.012

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  Talc is a kind of magnesium silicate, which have stable chemical property, a large surface area with special layered structure, and unique pore-structure. It has been wildly used in various fields including papermaking, coating, automotive industry and so on. In recent years, talcum powder has been successfully applied to sewage treatment because of its lipophilic-hydrophobic property, excellent adsorption property, rich reserves and low cost. There are relevant researches that the talcum powder has been used as a coagulant, coagulant aid, filter aid, adsorbent or oil absorbent. The physical and chemical properties of talc were introduced in this paper. Then the newest research on talcum powder used in papermaking wastewater, oily wastewater, dye wastewater, aromatic organic wastewater and heavy metal ions wastewater were reviewed. Meanwhile the modification methods of talcum powder in water treatment were summarized. And the advantages and disadvantages on the talcum powder used in treatment of various wastewaters were evaluated. Finally, some suggestions are provided for the relevant research and the developments, which are expected in the future.
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  Progress in Fracture Characterization and Prediction

  TANG Cheng

  . 2013, 31(21): 74-79. https://doi.org/10.3981/j.issn.1000-7857.2013.21.013

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  It is very important for exploration and development of oil and gas to comprehensively and accurately and quantitatively describe and predict fracture. Base on the basis of the literature investigation of fractures research findings around the world, from geological analysis, log fracture identification, curvature method, tectonic stress simulation, seismic fracture prediction and so on, the progress of fracture characterization and prediction are summarized. It is shown that the reservoir fractures can be classified into two types, including structural and non-structural fracture according to their origin. The structural fracture includes regional fracture, local fracture and complex structural fracture, in which the local structural fracture is related to fracture of fault and fold. The non-structural fracture can be classified into contraction fracture and related fracture of surface, which have 12 sub-types. Every type of fractures has different characteristics and origin. The main identification of fracture is combination of geological analysis and log interpretation, and then pattern recognition of outcrop, core and well logging will be established. Also quantitative calculation method for fracture is proposed using geological, logging and tectonic stress data. With the aid of those bases, the advantage and disadvantage of methods for detection and prediction of the fracture distribution are discussed. Finally the shortcoming and development of fracture research are pointed out.