Abstract:A new type of damper fastener is tested by using the hammer excitation method,and the damping performance is analyzed from four aspects(transmission rate; transmission loss rate;transmission loss and Z vibration level).The results show that in the range of 4~200 Hz,the transmission rate is mainly below 2.5%;the transmission loss rate is mainly above 97.5%;the transmission loss is mainly above 32 dB;and after calculating the track vertical vibration acceleration,Z vibration level is 86.15 dB;compared with the ordinary damper fastener,the vibration attenuation performance of the new type damper fastener has been significantly improved.The test shows that the hammer excitation method is effective,convenient operation,which is an excellent test method for the vibration attenuation performance of damper fasteners.

Abstract:In order to research the mechanical properties of 600 MPa grade high-strength steel bar after high temperature, the tensile strength test on HTRB600 high-strength steel bar after high temperature is conducted. The specimens are heated up to 20, 200, 300, 400, 500, 600, 700 and 800℃ using a electric furnace respectively, then the tensile test is carried out after the specimens are cooled in air and the yield strength, ultimate strenth, elastic modulus and stress-strain curve of the specimens are also measured and recorded simultaneously. The experimental results show that when the temperature is lower than 600℃, the stress-strain curve of the HTRB600 steel bar after high temperature has no obvious difference compared with that of the unheated specimens; When the temperature reaches 700℃, the yield strength and ultimate strength of the steel bar after high temperature reduce to 80% of those of the unheated specimens; When the temperature reaches 800℃, the yield strength of the steel bar after high temperature reduces to 60% of that of the unheated specimens whereas the ultimate strength s still maintaines at the same level to that of the 700℃ heated specimens. The influence of temperature on the elastic modulus of the HTRB600 steel bar after high temperature is also not ovbious. At last, the simplified calculation method for the stress-strain curve of HTRB600 steel bar after high temperature is proposed.

Abstract:In order to get the similar material rock model with high gravity, low strength and low modulus, the method of orthogonal experimental is used to analyze the material parameters sensitivity of rock-like sample with iron crystal sand. The percentage of aggregate content, the weight ratio of iron powder to barite powder, the weight ratio of iron powder plus barite powder to quartz sand with coarse particle and fine particle and the weight ratio of cement to plaster are selected as four-factor, three-level. Nine sets of material proportion plans are designed. Through weight, measure and uniaxial compression test, the parameters of density, compressive strength, elastic modulus and peak strain are obtained.. The range analysis is used to analyze the sensitivity of various factors. The results show that:the weight ratio of iron powder plus barite powder to quartz sand with coarse particle and fine particle mainly influences density and elastic modulus; the percentage of aggregate content mainly influences compressive strength; the weight ratio of iron to barite powder mainly influences peak strain; The influence of other factors is not obvious.

Abstract:Using the rock failure process analysis software-RFPA2D, we selected brittle granite as the object and carried out numerical crushing experiment under different loading rates, got the RFPA2D stress diagram and the acoustic emission diagram corresponding to the same loading. The results show that, compared to a single drill bit, the rock will form stress superposition inside when it is under dual drill bits, and the crack under the superposition of stress will impact on adjacent cracks, the crack tip can produce stress concentration, the crushing rock will release more energy and the counts of acoustic emission; with the increasing of loading rate, the total energy of acoustic emission and the vertical load released by the crushing rock will increase.

Abstract:In order to investigate the influence of recycled asphalt content on high and low temperature properties of foamed warm-mix asphalt, the softening point test, dynamic shear rheological test and BBR test are conducted with 0%, 20%, 40%, 60%, 80% recycled asphalt. The results indicate that, with the increase of recycled asphalt content, the softening point, rutting factor and fail temperature of the foam warm-mix asphalt increase gradually, and the high temperature performance of the asphalt binder is obviously improved. The low temperature crack resistance of foamed asphalt decreases with the increase of the proportion of recycled asphalt content. When the recycled asphalt content is more than 40%, the creep stiffness and creep strain rate of the foamed asphalt cannot meet the requirements of the specification, and the low temperature cracking performance is poor. So the proper amount of recycled asphalt is less than 60%.

Abstract:The reason of the failure of foundation treatment in a certain slope and deep artificial fill area is investigated by analyzing the site investigation and the settlement observation. The useful conclusions can be drawn:(1) the settlement in collapsible loess zone can be divided into 4 stages:the growth period, the stable period, the acceleration period and the last stable period. The increase of the rate of the ground subsidence is caused by the collapse of loess soil. The settlement observation time is suggested to be longer to assure the settlement of the construction in the last stable period.(2)the collapse of loess soil not only cause the differential ground subsidence, but also change the mechanical characteristics of pile foundation. Only relying on the stiffness of pile foundation to control the displacements of structure is dangerous, but the deformation of soil near the pile foundation should be considered as well. (3)When the foundation of the construction is in a certain slope, the cementation of soil grains in a low height is weaker than those in a high height, which causes the low area deforming largely.

Abstract:The influences of different water cement ratios (0.40~0.50)and different replacement rates (0%~30%)of recycled brick grain on the workability and elastic modulus of the recycled concrete are investigated based on the slumps experiment and elastic modulus experiment of those concrete mixtures. The test results indicated that with the increase of content of recycled brick grain, the workability and the elastic modulus become bad under the condition of the same water cement ratio. And when the replacement rate of recycled brick grain is 30% and water cement ratio is 0.50, the descend range is equal to 17.62% for its elastic modulus. Based on the test results, the prediction model of the elastic modulus is proposed for the recycled concrete with brick grain.

Abstract:The small deflection of the two dimensional functionally graded material (2D-FGM) thin plate (Ti-6Al-4V, Al 1100 and ZrO₂) is analyzed by the finite element method(FEM).The deflection value of 2D-FGM thin plate subjected to uniform distributed load with four edges simply-supported or clampedsupported is calculated under different temperatures. At the same time, the accuracy of this method is examined. The deflection distribution diagrams are obtained. Effects of temperature and porosity on the deflection of 2D-FGM thin plate are discussed. The results show that the influence of temperature and porosity on the load 2D-FGM thin plate is obvious. In the case of constant ambient temperature, the deflection of 2D-FGM thin plate with four edges clamped-supported and four edges simply-supported increases with the increasing of porosity. Under the condition of constant porosity, the deflection of 2D-FGM thin plate with four edges clamped-supported and four edges simply-supported increases with the increasing of temperature.

Abstract:This article takes the six story frame structure adding different stiffness wall as the analysis object. The effects of adding the rocking wall and the wall stiffness variation on the structure internal force distribution and the changing rule are studied. From the analysis results it is concluded that:when the interlayer stiffness of the framework is uneven, it has great influence on the internal force distribution of rocking wall and the force of the structure. The shear force and the bending moment of the rocking wall increase with the increasing of earthquake intensity and stiffness ratio. With the addition of the rocking wall, the seismic effect of the frame part decreases, and the emergence of the weak layer is prevented.

Abstract:The recycled concrete is made of recycled coarse aggregates rich in 40%~50% brick aggregates. And the water penetration height method and electric flux method are used in the test to investigate the effects of the replacement rate of brick coarse aggregate and fly ash on the water permeability and chloride ion penetration and further to find out the best replacement rate. Then, the rapid frozen thaw method is used to investigate the effects of the replacement rate. The results show that the impermeability of recycled concrete is lower than that of ordinary concrete. With the increase of the replacement rate, the impermeability of recycled concrete becomes lower. The fly ash has the modification effects on recycled concrete. The penetration resistance and freeze-thaw resistance performance of recycled concrete are the best when the replacement of cement with fly ash is 20%. Under the appropriate replacement ratio, the frost resistant grade of recycled concrete can reach the D100.

Abstract:Based on the high loess-filled project in Yan'an new district, a series of moistening deformation tests with different initial compaction degrees and initial water contents in high pressure are carried out for compacted Q₂ loess to study how the coefficient of moistening deformation change with the increasing of the vertical pressure, and the main factors influencing the moistening deformation characteristics. The results show that the-p curve greatly is different from different initial compaction degrees and initial moisture contents; Compaction degree and moisture content have a great influence on the moistening deformation characteristics of compacted Q₂ loess, the amount of moistening deformation saturated can decrease greatly by increasing them. Moreover, compacted Q₂ loess will lose collapsibility when its compaction degree is higher than 90% or moisture content is higher than 16.8%.

Abstract:Groundwater hydrochemical type is the characterization of water chemical composition and environment, as well as an important part of groundwater quality assessment. The monitoring data of groundwater quality in handan city are analyzed and classified according to O.A.Arliekin classification method. On the basis of groundwater hydrochemical type, the pollution reasons are analyzed. The results show that total dissolved solids, total hardness, chloride, sulfate, ammonia nitrogen and fluoride, etc. are the main causes of pollution.

Abstract:In the experimental study on vertical distribution of flow velocity in double layer vegetated channel, PVC cylindrical rods are simulated as a rigid vegetation. Three-dimensional ultrasonic Doppler speedometer ADV is used to measure velocities in different locations of the rectangular flume. The results show that:(1) the velocity profile behind tall rods exists four inflection points that divide the velocity profile curve into five parts. And the flow characteristics of each part are not identical. (2) the velocity profile behind short rods existes three inflection points that divide the velocity profile curve into four parts. The shapes of velocity profile between the height of tall rods and short rods are different and other parts are generally similar.(3) the velocities under the height of short rods are different, but velocity profile at all locations above the tall rods can appear to converge onto a single logarithmic profile with a slip velocity, which is consistent with the velocity distribution near the water surface of the non-vegetated layer.

Abstract:The early warning of water source pollution with biological monitoring method is studied. The zebrafish is used as the experimental object. And the SPSS according to behavioral difference of fish in different toxicity environment. The study shows that the dose effect relationship was exists between heavy metals, organic compounds and zebrafish mortality. As a result, toxicity testing methods on zebrafish can be used to carry on biological pre-alarm for water pollution.

Abstract:Shallow geothermal energy is defined in The Standard for Evaluation of Shallow Geothermal Energy as the heat energy which is "contained in the surface depth no more than 200 meters and not exceeds 25℃". In addition, there is no specific rule on the Borehole Heat Exchanger(BHE) depth in Technical Code for Ground-Source Heat Pump System. Generally take 100-120 meters, according to the actual engineering experience and calculation. A three-dimensional numerical heat transfer model is proposed in this paper,which calculates the heat transfer in different depths and analyzes the influence of various factors on the depth of BHE. Conclused that the flow rate in the pipe is the most important factor. Geothermal gradient, thermal physical properties of backfill material and the spacing between pipes also have influence on the heat transfer of the BHE in different depths.So in actual project,if we want increase BHE depth, we should increase the flow rate in the pipe and reasonablely increase BHE size.

Abstract:In order to study the solute transport in fissured clay, experimental apparatus for solute transport in fissured clay are developed based on previous saturated seepage experiments. The solute transport is monitored by measuring the conductivity of the tracer solution in the experimental setup law. The results show that the concentration of exudate in the bottom of the model tends to be stable in a short time, which indicates that the existence of cracks in the clay will cause the solute to pass through the clay layer rapidly and form preferential flow phenomena. The upper head of the clay layer has little effect on the solute concentration in the clay, and the effect of the water head is similar in the different soils.

Abstract:To study the adsorption effect of zeolite powder on heavy metal copper, the indoor test is carried out. And the natural zeolite powder, 4-A zeolite powder and modified zeolite powder based on the natural zeolite powder made by the high temperature roasting with fly ash as adsorbent are selected for static adsorption of heavy metal Cu²⁺. In order to verify the ability of adsorption removal of Cu²⁺, cement is added as adsorbent. The static adsorption experiment shows that the adsorption capability for the Cu²⁺ is as follows:4-A zeolite powder ≈ modified zeolite powder > natural zeolite powder > > cement. Considering the economic factors and preparation technology, the modified zeolite powder is the best choice to removing Cu²⁺. The optimum content of modified zeolite powder removal Cu²⁺ is:2 g:100 mg/L. The pH between 5-8 is better for the adsorption.

Abstract:This paper samples PM_2.5 and analyzes its components in January, April, July, and October of 2013 and 2014. The results showed that the annual concentrations of PM_2.5 are 170.4 μg·m^-3 and 144.0 μg·m^-3. The annual concentration of PM_2.5 decreases 15.5%, compared to 2013. The orders of OC are winter(31.7 μg·m^-3)>autumn(24.4 μg·m^-3)>spring(9.1 μg·m^-3)>spring(5.6 μg·m^-3). And the orders of SOC are autumn (13.1 μg·m^-3)>winter(8.8 μg·m^-3)>spring(2.4 μg·m^-3)>summer(2.0 μg·m^-3), which account for 24.6%、34.6%、43.9%, and 27.7% of OC, respectively. The annual scatter coefficient is 524.9 Mm^-1 by using the IMPROVE equation. The scatter coefficient of winter is 872.6 Mm^-1, which is notable higher than 564.8 Mm^-1 of autumn, 333.9 Mm^-1 of summer and 328.4 Mm^-1 of spring. Ammonium sulfate is the largest contributor, which contributed to 33.9% of scatter coefficient, followed by 25.3% of ammonium nitrate, 20.2% of organic matter, 15.4% of PM_2.5-10, and 5.7% of dust.

Abstract:The modified kaolin clay/SBRnanocomposite prepared through the latex compounding method has excellent dispersibility, which doesn't exist reunion phenomenon even if 50Phr kaolin wasadded. The problems arethe delay of curing starting pointandsignificantly prolonged of curing time. Through infrared (FTIR) analysis, it was found that the hydroxyl on the surface of the kaolinite has strong adsorption ability, which can absorb the moisture in the air andparticleswith unpaired electron.It can effectively shorten the curing time of the composite material by using the chelating agent TEA and alcohols PEG600 to coat the kaolin surface.

Abstract:The Hunan Chenzhou and Xinhua graphite with different graphitization degree were oxidized by the modified Hummers method usingdifferent amounts of oxidizingagent(KMnO₄),X-ray diffraction (XRD),Scanning electron microscope(SEM), Fourier transform infrared (FT-IR) spectroscopy,Raman spectroscopy(Raman),Transmission electron microscopy (TEM),X-ray photoelectron spectroscopy(XPS),The testing methods were used to study the structure of graphite samples and their oxidation products.The results showed that the hydroxyl group (C-OH), ethylene (C-O-C) and carboxyl group (COOH) were connected to the graphite layersduring the course of oxidation, but the graphite with lower graphitization degree was easier to be oxidized when the amount of usedKMnO₄ is lower;While the graphite with higher graphitization degree was easier to be oxidized when using more oxidizing agent.With the increase of the amount of KMnO₄, the structure disorder degree of the two kinds of graphite increased gradually.But under the same amount of KMnO₄, the oxidation productof graphitewith low graphitization degree had higher degree of disorder.It can be speculated that:On the one hand,the contact area ofgraphite with potassium permanganate and solution is larger due to the particle size of graphite with low-degree of metamorphismis smaller;On the other hand, the graphite with low degree of graphitization has more C -C and easily oxidizeddue to its high chemical activity.

Abstract:The cast thin section analysis, high-pressure mercury, constant-speed mercury porosimetry, steady seepage, X-ray diffraction and acoustic emission of rocks under triaxial compression methods are used to experimentally investigate the reservoir space and physical property parameters of the Chang 81 tight sandstone reservoir in the Zhenbei Area. The results show that the reservoir space is dominated by intergranular pore and intergranular dissolution pore, followed by intragranular dissolution pore (feldspar dissolved pore and lithic dissolved pore), and only few areas exhibit intercrystalline pore. Three types of pore structures are observed, namely less wide form, rather narrow form and narrow form. The quality of tight sandstone reservoir is mainly controlled by throat. The results show that the research area has characteristics of the low stress sensitivity, high brittleness index and small horizontal principal stress difference. It's suitable for SRV fracturing.

Abstract:Aiming at the characteristics of easy deformation and vibration of ball screw under the action of external force, the three-dimensional assembly model of ball screw is established by using SolidWorks software, and then it is simplified into ANSYS Workbench software. After setting the constraint conditions and meshing the model, the modal analysis is carried out to obtain the first six natural frequencies and vibration modes of ball screw. The results show that the first six vibration modes of ball screw are bending deformation, and the middle position's vibration amplitude of the screw is the largest in the natural frequency of the sixth order, which is the weak link of ball screw.

Abstract:The heat treatment technology of P92 steel is studied by comparison of the tension properties, observation of the metallurgical structures and the fracture topographies analysis. It is shown that the ultimate tensile strength decreases and the ductility increases with the tempering temperature increasing in the range of 200℃~700℃, and the change reverses when the tempering temperature is in the range of 700℃~900℃. The optimal tempering temperature for P92 steel is 700℃ in consideration of the static toughness when it is tempered below A_C1.