Abstract:The prefabricated external prestressed concrete wind tower with split and variable diameters keeps its integrity by its own gravity and friction before the steel strand is stretched. There is no previous research about the influence of the stressing order on the stress state of the tower. A layered-shell element model is built to simulate the unstressed state and the stressing process. Construction procedure is developed according to those results. Vibrational chord strain gauges are adopted for monitoring the strain of key positions during the stressing process. It is found that the results produced by layered-shell element model arecompatible with those from the field test and it is suitable for construction process analysis of the prefabricated tower. The stability of the structure during the stressing process proves the validity of the construction procedure,which can provide a reference for similar projects.

Abstract:Based on the double-K model,the effect of seawater curing and seawater agitation on the fracture properties of concrete was studied by three-point bending test in this paper. The test results show that:Seawater mixing reduces significantly the initiation load and peak load of concrete,and also reduces the initiation fracture toughness and instability fracture toughness of concrete. The maxima of decreasingare 52.6% and 25.6% respectively. The effect of seawater maintenance on the fracture parameters of double-K is relatively small,and the ranges of fracture toughness and instability toughness are 3.2%~23.4% and 12.7%~20.8%,respectively. In addition,under the influence of seawater,the calculated fracture energy is obviously reduced,and the range of decrease is 14.5%~28.1%.The effect of seawater on the compressive strength of concrete cubes is fairly minor.

Abstract:In order to analyze the effect of prestressed cable on the excavation stability of super-span underground engineering, taking a large span underground engineering as the example, the prestress value and space of prestressed cable were analyzed by numerical simulation. The principle of vault displacement and liner maximum principal stress under different prestress value and space of prestressed cable were obtained. The results show that with the increase of the anchor cable prestress the vault displacement and liner maximum principal stress decrease gradually, however, the maximum stress of the anchor cable shows a trend of increasing at first and then decreasing. With the increase of the space of anchor cable, the vault displacement and liner maximum principal stress increase gradually, the maximum stress of the anchor cable shows a trend of increasing at first and then decreasing. It is recommended that the prestress value of the anchor cable should be 200 tons and the space should be 5 m.

Abstract:The study on the effect of drainage conditions on clay strength was carried out with double fold linear strain path triaxial test controlled by maximum drainage volumetric strain. The results show that under the condition of double fold linear strain path,the peak shear strength is merely linear to the maximum drainage volumetric strain of soil. In the whole test the sample does not reach the critical state. The effect of volumetric strain and shear strain on shear characteristic are related to shear strength level.

Abstract:Taking a proposed residential building in Ansai District,Yanan as an example,a program of variable stiffness composite foundation is proposed. The variable stiffness composite foundation of half-hard and half-soft rock geological conditions is carried out by numerical simulation with the finite element analysis software MIDAS GTS NX. The settlement characteristics of foundation are studied by changing the design parameters of soil modulus,pile modulus,pile spacing,pile length and so on. The suitability of variable stiffness composite foundation is based on the study of differential settlement. The results show that differential settlement of half-hard and half-soft rock foundation can be solved by the variable stiffness composite foundation. The differential settlement can be controlled within a reasonable range by adjusting the design parameters of variable stiffn ess composite foundation.

Abstract:Experiments with different strain rate on granite and marble under impact compressive loading are conducted with the modified split Hopkinson pressure bar. Through verifying the validity of the test,the reliability of the data is proved. The experimental results show that the strain rate obviously affects the dynamic mechanical properties of these two kinds of rock materials,the dynamic compressive strength,peak stress and elastic modulus with different impact velocities show significant strain rate correlation,peak strain changes little,the relationship between the peak stress-impact velocity and the elastic modulus-impact velocity of granite and marble is analyzed,and both of them show weak power function;In the process of loading,granite showed more obvious dynamic brittleness,from destruction form,most of the granite present axial splitting mode,the fragment degree of marble is higher and the marble present crushing mode,conducting the comparison and analysis from the perspective of microstructure.

Abstract:This paper discussed the transversely isotropy and heterogeneity of the slope and analyzed the calculation method considering transverse isotropy and heterogeneity. The anti-skid moment calculation formula of the soil and the anti-slide pile was developed by the limit equilibrium method. Calculation method of slope reinforced by anti-slide piles considering soil strength transversely isotropic and heterogeneous was developed by modifying the safety factor calculation for the anti-skid moment calculation formula of the soil and the anti-slide pile. The situ case showed that when the horizontal cohesion was assumed to be a constant,the relative error of the safety factor of the transversely isotropic slope was less than that without considering the transversely isotropic nature of the soil strength,which meant that it is necessary to consider the transversely isotropic nature of the soil strength in the anti-slide pile reinforced slope engineering.

Abstract:In this paper,a large deformation finite element analysis based on the CEL technique is conducted to simulate the keying process of plate anchors. Prior to parametric study,the large deformation finite element analysis results are validated against with centrifuge model test data,with good agreement obtained. From local soil flow mechanism,it can be found that the keying process of plate anchors is changed. For different chain-sea level angle,the vertical load is the maximum value when the plate anchors are pulling at 90 degrees. At the same time,loss of embedment of plate anchors is also the largest. When the anchor eye eccentricity ratio is relatively small,the loss of embedment of plate anchors is very large,and which is mainly concentrated in the plate anchors rotated to 45 degrees. When the soil-anchors friction coefficient large than 0.5,the loss of embedment of the plate anchors varies little.

Abstract:Taking the top bar loads of clayey soil slope as the research object, the mathematic expression of the safe distance is deduced by using the Swedish article points method and limit equilibrium theory. Then the finite element numerical simulation on a practical engineering case is calculated,and the reliability of the mathematical expression is verified.

Abstract:In shield tunneling approaching projects,the construction activities are of large risks for shield tunneling with an underground road overlapped on it. Considering the coupling deformation of tunnel and underground road,the analysis-calculation model of shield tunneling below an underground road is established with Finite-Difference-Method. Thus,soil movement and underground structure deformation can be acquired. The results show that soil movement appears mainly in three enveloped area. For underground road,the additional deformation is much heavier on the top plate and bottom plate above the tunnel crown. Moreover,the "horizontal egg" deformation of shield lining for three enveloped situation decreases compared with semi-infinite situation.

Abstract:Based on Biot consolidation theory,fluid flow through fractures and fluid-solid coupling theories,a three-dimension model of concrete pavement is established in COMSOL Mutiphysics software to study variation of the pore water pressure through fractures and whether it can exert bad effects on the pavement under the vehicle loads condition. The displacement of pavement,variation trend and dissipating regular of pore water pressure are compared while vehicle passed the reference line of the road under four different pavement conditions,including non-crack,horizonal crack,perpendicular crack and cross crack. The results of numerical analysis show that perpendicular crack has a positive effect on the dissipation of pore water pressure compared to the horizonal one. Pore water pressure reaches peak on the pavement full of horizonal and cross cracks,which damage the road itself to some extent. Fractures have no significant effects on the displacement of the pavement.

Abstract:On the basis of DSR test,the influence of diatomite quality and difference in base asphalt on the rheological property of modified asphalt was analyzed by choosing diatomite from different phase of mineral refining and base asphalt with different oil source and grade to modify asphalt separately. The results indicate that purified diatomite obtained after mineral refining can improve the anti-deformation property of asphalt effectively,but the modification effect of original diatomite and tailing diatomite is no good;the anti-deformation property of modified asphalt is also affected by base asphalt with different oil source,and it will make a different modification effect;at the same time,the higher grade of base asphalt,the lower anti-deformation property of asphalt after modification.

Abstract:In order to reduce and prevent the accidents of the formwork support frame from falling,the management level of safety warning should be improved. On the basis of the identification and analysis of the hazard source of the accident caused by the falling of the frame body,the dangerous area and the warning grade are divided according to the different falling objects of the frame body. At the same time,based on the requirement analysis of early warning management information,the system framework including information collection layer,network layer,interaction layer and application layer is constructed. Finally,the flow chart of early warning and management system of formwork support system is constructed based on building information model and radio frequency identification technology. The results show that the system can collect,locate and track hazard information. The automatic identification and warning of the dangerous area can realize the visual analysis and intelligent early warning of the fall accident of the person who put up the frame and the construction personnel on the frame.

Abstract:The claystone from Permian Shihezi Formation in Sanling area,Handan,was analyzed for minerals by using optical microscope and electronic microprobe analyzer (EMPA),for major elements by using X-ray fluorescence spectrum (XRF) analyzer,and for trace elements by using inductively coupled plasma mass spectrometry (ICP-MS) analyzer. The result shows that,(1) the claystone is composed of illite,quartz,pyrophyllite,chamosite and albite,with a trace amount of chalcopyrite,monazite and zircon,and such a mineral assemablage is similar to propylite;(2) the claystone is abnormally enriched in rare earth elements (REE),especially in light ones and some middle ones,which is probably the result from a hydrothermal action;and (3) it is valuable as a potential resource.

Abstract:In order to study the characteristics and sources of heavy metals in aerosol in the coal mine area of eastern foot of Taihang Mountain,PM_2.5 and PM₁₀ samples were collected in Fengfeng mining area of Handan,China in 2017. The heavy metal contents in the sample were measured by Inductively Coupled Plasma Mass Spectrometry. The mean mass concentration of PM_2.5 in spring,summer,autumn and winter in Fengfeng mining area were 84、108、107 and174 μg/m³ respectively. The PM₁₀ mean mass concentration in spring,summer and autumn were 204,177 and 179 μg/m³ respectively. PM_2.5 and PM₁₀ mass concentration exceeded Chinese National Ambient Air Quality Standards (grade-Ⅱ),it indicated that air pollution in coal mining area was more serious. The ratio of PM_2.5/PM₁₀ in summer and autumn was obviously higher than that in spring,which may be related to the strong photochemical reaction in summer and autumn. The metal contents of Zn in PM_2.5 in Fengfeng mining area were the highest,and the contents of other elements from high to low are Pb,Mn,Cr,Cu,As,Mo,V,Sn,Ni,Cd,Co,etc. The content of Zn in PM₁₀ was the highest,followed by Mn,the contents of other elements ranged from high to low in order of Pb,Cr,Cu,V,As,Mo,Ni,Sn,Cd,Co,and so on. The enrichment coefficient of Cd elements in PM_2.5 and PM₁₀ in Fengfeng mining area was more than 100,which is seriously enriched and influenced by human activities. The enrichment coefficient of Mo,Pb,Sn and Zn elements were more than 10,which indicated that Mo,Pb,Sn and Zn were slightly enriched in Fengfeng mining area and were affected by human activities. The enrichment factors of As,Cr,Ni,V,Mn and Co were less than 10,which indicated that the seven elements of Cu,As,Cr,Ni,V,Mn and Co mainly come from the crust.

Abstract:In order to investigate the effect of soft rock softening behavior on uniaxial compressive properties,the limestone of Taiyuan formation of No. 1 coal floor in Chensilou Coal Mine,Henan Province is selected as experimental materials. Under three different loading rates,uniaxial compression tests were carried out on the samples under different soaking times,and the soaking effects on the compressive properties of limestone were obtained. The results of the study are as follows:at a certain loading rate,the compressive strength and elastic modulus decrease gradually with the increase of soaking time,and the decreasing extent e is smaller and smaller. With the increase of soaking time,the specimen changes gradually from elastic deformation to plastic deformation,but the limit strain is basically unchanged. The total strain energy and elastic energy are exponentially reduced,and the variation of dissipation energy with immersion time can be fitted by linear relation.

Abstract:Taking Jingbian gas field A area as an example,this paper analyzes the interlayer production difference and main control factors of commingling production gas reservoir by using drilling and production dynamic data and through calculation and analysis of geological reserves,dynamic reserves,discharge radius and dynamic-static reserves ratio. The results show that the dynamic and static reserve ratio of the small layer is 6.8% minimum and 79.8% maximum in Jingbian gas field. The utilization of gas reservoir shows a pattern of one high and the rest low,the utilization of Ma 513 is prominent,and the utilization of other layers is generally low;The correlation analysis shows that the interlayer production difference is controlled by reservoir physical properties,especially permeability,which shows that the ratio of static and dynamic reserves of small layer increases exponentially with permeability.

Abstract:The microstructures and mechanical properties of an ultrahigh-carbon steel with 1.37 wt.%C subjected to austenitization at single γ phase region and austempering at low temperatures have been studied. The results show that a superbainite comprising lamar bainite ferrite and film-type retained austenite is generated. An impact absorbed energy of 12.7 J,a fraction strength of 1 622 MPa and an elongation of 5.5% are obtained for UHCS-1.37C austempered at 310℃ for 8 h. The combination of excellent strength and toughness is attributed to the superbainite.

Abstract:The corrosion resistance of Al-Cu-Mg-Ag alloy was studied by intergranular corrosion test and exfoliation corrosion test. The mechanism was discussed by metallographic analysis and transmission electron microscopy. The results show that,the corrosion resistance of the alloy can be enhanced by appropriate rolling deformation. With increasing the deformation amount,the strengthening phases deform and move to the grain boundaries,which leads to a narrower precipitation free zone (PFZ). The corrosion channel narrows and the corrosion resistance of the alloy increase. On the other hand,the elongaged grains along the rolling direction can decrease the exfoliation resistance of the alloy. As a result,the corrosion resistance of the alloy with a relative smaller deformation amount (10~50%) is increased,and that of the alloy with a larger deformation amount (80%) is decreased.

Abstract:Considering the influence of random uncertain factors,the reliability analysis for the working cylinder body of the 50MN three-beam and four-post forging hydraulic press is carried out. Using parametric design language ANSYS (APDL),the three-dimensional parametric model of cylinder body is established. According to the stress-strength interference principle,the reliability model of cylinder is constructed. Setting the geometry size,load and material strength of the working cylinder body as random variables obeying a certain distribution,using the ANSYS/PDS module and Monte-Carlo simulation technology,the paper analyzes the reliability of the cylinder body. Through the sensitivity analysis,the influence of the uncertainty variables on the cylinder body reliability is discussed. This study can provide a theoretical basis for the design of the working cylinder body of the forging hydraulic press,and it has important significance for the reliability research of the cylinder block.

Abstract:This paper aims to explore the major factors influencing teaching quality of BIM in this mode. Firstly,The BIM competition-related data is obtained by questionnaire. Secondly,the major factors influencing teaching quality of BIM in this mode is given based on decision tree. Thirdly,an experiment based on support vector machine is carried out to verify that the above factors is indeed the major factors influencing teaching quality of BIM. Finally,the above major factors are analyzed combined with the students surveyed.. The major factors influencing teaching quality of BIM include students' participation in other affairs,students' understanding of software before training,students' attention to the competition,the conflict between training and daily courses,computer equipment during the training,etc.

Abstract:In this paper,we investigate the pricing problem of stock loan with periodic dividends in the framework of uncertainty theory. Based on the stock model with periodic dividends,the uncertain differential equation governing the value of stock loan is derived. Therefore,the formulas of price of stock loan can be obtained to provide support to decision-making for investors with large equity positions. In order to validate the effectiveness of the proposed method,the experimental datasets extracted from stock market are used as the testing target. The experimental results show that the stockholders should borrow through the stock market.