Abstract:In order to explore the piping mechanism and the mechanical properties after piping of soils with different fine particle content, three kinds of soils with different fine particle content were selected and piping up was simulated by self-developed piping triaxial apparatus. Through piping test and drainage shear test after piping, the effects of fine particle content on critical hydraulic gradient, cumulative sand inflow, peak strength and volume change were analyzed. The results show that the critical hydraulic gradient and critical flow velocity increase with the increase of fine particle content before piping. The growth rate of cumulative sand inflow decreases with time under the action of higher hydraulic gradient. The cumulative time of sand gushing decreases with the increase of fine particle content when the same fine particle content is lost. With the increase of fine particle content, the peak strength of soil changes irregularly after piping, the volume of soil first shears and then dilates, and the maximum volume shrinkage of sample increases with the increase of fine particle content.

Abstract:In order to study the shear strength characteristics of saturated soft clay under different degree of consolidation, the stress-strain controlled triaxial shear permeability tester was used to carry out triaxial shear tests of saturated soft clay under different degree of consolidation. The effects of different degree of consolidation under different confining pressures on pore pressure increment and shear strength of soil were analyzed. The results show that in partial undrained shear tests, the lower the pre-shear consolidation degree and the larger the pre-shear hole pressure, the smaller the pore pressure increment caused by shear, but the larger the total hole pressure and the lower the undrained strength. By normalization, the correlation between pore pressure increment and consolidation degree is obtained.

Abstract:A three-dimensional finite element analysis of the model of the Nuozhadu core wall rockfill dam is performed to make a comparison of the two loading-unloading criteria commonly used in the Duncan-Chang model. The influences of the value of the rebound modulus on stress and deformation of the dam are analyzed. The results demonstrate that in the process of construction and impounding, the loading and unloading criterion based on the loading function (law 1 for short) will lead to a bigger unloading fracture zone. The calculation of settlement in this law is nearly half of that in the loading and unloading criteria based on stress level s and deviatoric stress (σ₁-σ₃) (law 2 for short). The alternative of loading-unloading criteria has little influence on the stress of dam. Monitoring data of Nuozhadu rockfill dam demonstrates that the calculation of settlement is more accurate in law 2. In case of taking law 2 as the loading and unloading criteria, the influence of modulus of resilience mainly shows that the settlement of impounding dam is decreased when modulus of resilience increase.

Abstract:In order to study the mechanical properties of GFRP plate-concrete composite beams, the ABAQUS finite element software was used to establish the concrete beam model reinforced by glass fiber reinforced composites (GFRP). The load-span deflection curve and bearing capacity of composite beams were verified to show the rationality of establishing a model method. The component models of three different strength grades of C25, C30 and C40 were designed, and the conclusions about the mechanical properties of GFRP plate-concrete composite beams were analyzed. Conclusions:(1)The results show that under the same load, the ultimate bearing capacity of the composite beam increases with the increase of concrete strength grade, and the ductility decreases with the increase of concrete strength grade.(2) Increasing the concrete strength grade can effectively increase the ultimate bearing capacity of the composite beam.(3) GFRP panels can improve the flexural capacity of composite beams.(4) GFRP plateconcrete composite beam is mainly divided into two stages:elastic stage and working with crack.

Abstract:In order to study the effect of sand rate on the fracture properties of recycled concrete, recycled concrete was prepared based on RC25, and recycled concrete beam specimens with sand ratios of 25%, 30%, 35%, 40%, 45% and 50% were produced. Through the three-point bending test of the beam, the variation of the fracture performance of the brick-rich recycled concrete with the sand ratio was studied from the aspects of fracture toughness and fracture energy. The results show that the fracture toughness and fracture energy of the brick-recycled concrete increase first and then decrease with the increase of sand rate. When the sand rate increases from 25% to 35%, the fracture toughness increases. By 8.43%, the fracture energy increases by 10.73%, and when the sand ratio increases from 35% to 50%, the fracture toughness decreases by 3.81%, the fracture energy decreases by 11.29%. The fracture toughness at a sand ratio less than 35% is more susceptible to changes in sand rate compared with that at a sand ratio greater than 35%, which does not happen to the fracture energy.

Abstract:In order to investigate the compressive and shrinkage properties of fully reclaimed coarse aggregate recycled concrete under different curing conditions, three kinds of curing conditions were used in this experiment:film covering curing, dry and wet circulation curing and water immersion curing. Experimental study on compressive strength and shrinkage properties of recycled concrete with 1 d,3 d, 7 d, 14 d, 28 d, 45 d, 60 d, 90 d and 120 d was carried out under these three curing conditions. The results show that under these three different curing conditions, the compressive strength and shrinkage strain of recycled concrete increase with the increase of curing age. At 7 d, the compressive strength of recycled concrete was not significantly different under the three curing conditions. At 14 d, the film coverage and immersion maintenance were reduced by 8.7% and 14.2% respectively compared with the compressive strength of dry and wet circulation curing. Under the three curing conditions, the shrinkage strain of recycled concrete at 90d tends to be stable. At 120 d, the shrinkage strain of the film covering curing is 11.18% higher than that of the dry and wet cycle. The immersion curing shows swelling.

Abstract:In order to analyze the influence of foudation pit excavation on surrounding environment Based on the numerical simulation method of particle flow, the ideal particle system is constructed by boundary servo method, and the micro-mechanical parameters of rock and soil are calibrated by linear contact bond model. On this basis, the influence of foundation pit excavation on surrounding environment is analyzed. The results show that the ground deformation of 60-70m away from the foundation pit wall is about 5mm after excavation, the relative deformation of pipeline at 60-70m away from the foundation pit wall is less than 3mm, which will not cause uneven settlement of pipeline and damage; the plain filling and muddy clay around the failure foundation pit of pile wall will slide to the foundation pit, and the collapse range affects 10m approximately from the inner wall of the foundation pit, which is about 2~3 times the depth of the foundation pit. The research results can provide reference for the judgment of the stability of foundation pit wall and the deformation control of surrounding soil.

Abstract:The mechanical parameters of composite materials with inclusion particles are important in engineering. Based on the computational homogenization method and the random periodic composite material model generation algorithm, a method was proposed to calculate the elastic modulus of the composite material with inclusion particles from representative elementary volume, and the influence of the distribution, size and content of the inclusion particles on the mechanical parameters of the composite material was studied. The composites show isotropy when the particles are randomly distributed and anisotropy when the particles are distributed along a certain direction. The mechanical parameters of composites become stable with the increase of element size. The elastic modulus increases with the increase of particle content, and poisson's ratio decreases with the increase of particle content. The results show that the calculation of homogenization is an effective method to study the mechanical parameters of composite materials.

Abstract:In order to determine characteristics of deformation of the deep excavations in Xi'an subway station, the measured data of the deformation of the deep excavations of 18 subway stations were collected. According to the measured data, the characteristics of lateral displacement of the retaining structure and ground surface settlement caused by deep excavations are statistically studied, and the research results are compared with the deep excavations in other areas. The research shows that:The shape of the lateral displacement curve of the deep excavations' retaining structure is"bulging shape", and the maximum lateral displacement point depth is above the excavation surface; the maximum lateral displacement value ranges from 0.03%H to 0.12%H (H is excavation depth), and decreases with the increase of insertion ratio; the ground surface settlement curve is"groove shape", and the maximum surface settlement position appears at 0.51H; the maximum surface settlement is about 0.06%H, and increase of insertion ratio has no significant effect on the surface settlement; the maximum surface settlement increases with the increase of maximum lateral displacement, and its ratio is approximately equal to 1.10. The research results can provide reference for the deformation prediction, design and construction of similar deep excavations in Xi'an.

Abstract:In order to avoid the inconsiderateness of force and displacement of the structure in the process of secondary cable adjustment of the suspender force of long-span basket handle arch.Use a 450m long-span basket handle arch as engineering background, the process of the cable the influence matrix increase the weighting coefficient, using MATLAB to solve the weighted least-squares solution of equation, after a small amount of iterative computation, the cable force difference is stable.Research shows that:The relative error of the measured cable force with completion cable forces can be controlled within 5%, fully meet the specification limit requirements.The way of considering the geometric nonlinear effect during finite element calculation reduced the influence of the effect on structure.As a way of accelerate convergence, the weighted influence matrix has uniform convergence speed.

Abstract:Based on foundation pit project near high-speed railway bridge pier in China, a twodimensional finite- element model is established by numerical analysis method, and the influences of four factors on the deformation of high-speed railway bridge piers are discussed:the insertion ratio of envelope structure, inner supports, isolation pile and distance of foundation pit from pier. The results show that the insertion ratio has little effect on the maximum deformation of the horizontal displacement and the overall settlement of the pier; the inner supports can reduce the settlement and horizontal displacement of the pier, increasing the number of inner supports has little effect on deformation; the isolation pile cannot reduce the deformation; distance affects both horizontal displacement and overall settlement, but has little effect on the settlement difference.

Abstract:In order to improve the construction quality and management efficiency of prefabricated buildings, the BIM technology and its application in different stages, from architectural design, prefabricated production, engineering construction to the maintenance of the whole prefabricated building, was introduced. According to the construction requirements of each stage, different quality management systems have been formulated and developed from three aspects:before, during and after the event. According to the quality control requirements of different construction sites and different construction stages, BIM technology is adopted to formulate the corresponding quality control process and effective management measures. The quality problems in the construction of prefabricated buildings are effectively managed, and the structure, quality and management of prefabricated buildings are comprehensively improved.

Abstract:The mechanical analysis of guide card is missing. In order to fill this gap, the author uses the method of combining qualitative analysis with quantitative analysis to analyze the layout of drainage pipeline, the distribution and combination of pipeline load and the mechanical model of guide card in coal mine vertical shaft. Thus, a method of choosing guide card suitable for engineering design is sorted out.

Abstract:By introducing fractional calculus theory to the rock creep model, pronounced effect was obtained in describing the creep property of rock mass. However, the orders of the conventional fractional viscous body almost are almost constant, so a single element cannot be used to simulate the attenuation stage, steady stage or the accelerating stage of rock creep. According to the fractional calculus theory, a modified fractional viscous body with unsteady differential orders was developed. Then, through connecting it and the ideal viscoelastic body that introduced the fractional calculus with the traditional elastic body, a new nonlinear viscoelasto-plastic creep model for rocks was established. In this paper, the creep equation of the model was deduced, and the rationality of which was verified by using creep test data of rocks. What's more, the paper made a comparison between the proposed model and the Nishihara model, the HoHai model, respectively. The results indicate that the fitting curves and test curves conform very well to each other. The proposed model has high accuracy and rationality and can well reflect the whole stages of rock creep process.

Abstract:The petrology and origin of kaolinite rocks under coal No.9 of Taiyuan Formation in Datong coalfield were studied based on the polarized microscope. Four texture components, i.e. clast (including terrigenous clast,volcanic quartz crystal pyroclast,volcanic biotite crystal pyroclast,devitrified"flint-like" vitric clast), cryptocrystalline kaolinite graupe, kaolinite crystal clast and kaolinite matrix, were identified under polarized microscope. The research shows that the main rock types of this bed of kaolinite rock were tuffaceous graupe kaolinite rock with thin feldspar pseudomorphic crystal kaolinite rock on the top, and intercalated with tuffaceous sandstone bed at middle part. This bed of kaolinite rock was originated from the tuffaceous sediments reworked by water current at the basin bottom. Especially, the new formation mechanism of abundant graupe were firstly submitted:that is, the cryptocrystalline kaolinite graupe is the altered products of silica-alumna vitric clast, which was reworked by water current in the basin bottom and show no evidence of volcanic origin.

Abstract:The petrified wood from the No. 2 coal seam of Permian Shanxi Formation in Wutongzhuang Mine, Handan area, was studied by using optical microscope, X-ray fluorescence spectrum (XRF) and inductively coupled plasma mass spectrometry (ICP-MS) analyzers for its mineralogy, major and trace elements, respectively. The result shows that, (1) the petrified wood is mainly composed of telinite and chalcedony, with an amount of epigenetic calcite micro-vein; (2)Comparing to the upper continental crust, the fossil is relatively rich in Sr, Zr, Nb, Mo and Cd, and lack in Li、Rb、Cs、Co、La、Ce、Pr、Tl、Bi and Th, and its characteristic elemental pairs have an obvious differentiation; normalized to chondrite, the rare earth elements(REE)pattern is a convex curve without Ce anomaly and with a moderately negative Eu anomaly, which suggests that the REE is mainly determined by the silicification closely associated with the low-temperature hydrothermal activity during the Permian coalification.

Abstract:In order to study the creep characteristics of sandstone, the conventional triaxial and creep experiments of the sample under 10MPa confining pressures were carried out by using the full-automatic triaxial servo. On this basis, in order to simulate the whole creep process effectively, a nonlinear creep model with fractional derivatives is proposed and verified. The results show that the cyclic creep rate and axial creep rate of the specimens are close at the creep attenuation and stabilization stage. In the creep acceleration stage, the creep speed of the sample increases sharply. The accelerated creep occurs in the annular direction before in the axial direction, and the cyclic acceleration creep rate is higher. In addition, it was found that the steady-state creep speed increased with the increase of stress level, and the annular steady creep speed increased more quickly than the axial creep speed, suggesting that the annular creep speed was much more affected by stress level.The non-linear creep model with fractional derivative established in this paper can simulate the whole creep process well and has high accuracy.

Abstract:In order to reveal the trend of phenological period and the law of response to climatic factors in the grassland of Xilin Gol League, this paper extracted the phenological period of Xilin Gol League grassland by using the method of double logistic function fitting and dynamic threshold based on the MODIS-NDVI dataset from 2002 to 2014.This study investigated patterns of the spatiotemporal variations in phenology and its possible influence factors. The results show that:(1) During the research period, the grassland greenup of Xilin Gol League showed an early trend, the withering period showed a delayed trend, and the growth period showed an extended trend.(2)In the study area, 25.93% area of the Grassland greenup was negatively correlated with precipitation, 57.24% was negatively correlated with air temperature. Sunshine hours had no significant effect on the grassland greenup. 21.65% area of the Grassland withering period was negatively correlated with air temperature, 22.24% was negatively correlated with sunshine hours. Precipitation had no significant effect on the grassland withering period.

Abstract:Energy pile is a new building energy saving technology with both heat exchange and load bearing functions. However, there are few studies aimed at heat transfer performance of energy piles under thermal-cold cycling treatment. In this paper, a novel test system is proposed and fabricated to investigate the heat transfer performance of precast single U concrete energy pile in sand by model test method. The test results show that heat transfer from pile to soil is more easily in the process of energy piles and the difference of temperature along the pile is small and distributed evenly. In addition, the influence range of soil temperature field under cold cycles is greater than the heat cycles. With the decrease of temperature difference between pile and soil, the heat transfer efficiency also decreases.

Abstract:The traditional ceramic roller threading manual loading and unloading assembly method has high labor intensity and low production efficiency. In order to reduce the labor intensity of workers and improve the efficiency of threading assembly, ceramic roller is taken as the research object. Based on the analysis of the process of ceramic roller shaft assembly, the loading and unloading system for ceramic roller is developed by three-dimensional modeling. The paper focuses on the detailed design of the material storage device, the whole material feeding device and the feeding device of the ceramic roller automatic feeding machine. The developed automatic roller feeding machine and the blanking robot realize the simultaneous operation of the ceramic roller body and the rotating shaft. The storage and loading and unloading at the same time improve the efficiency of the loading and unloading system. The development of the special winding and assembly system for the ceramic roller provides a good foundation for the assembly automation of the roller in the future.

Abstract:In view of the dynamic characteristics of flexible job shop scheduling under machine fault disturbance and the ambiguity of job delivery time, this paper adopts a rolling window rescheduling strategy driven by event and cycle, and uses the method of linear weighted sum to establish a multiobjective flexible job shop dynamic scheduling model with the objective of minimizing the maximum completion time, minimizing energy consumption and maximizing customer satisfaction. A GASA algorithm combining genetic algorithm with simulated annealing algorithm is designed. The effectiveness of the algorithm is verified by comparing the simulation results with those obtained by genetic algorithm.

Abstract:As one of the key parts of the automobile, suspension can directly determine the ride comfort and driving safety. In order to establish the effective controller of the automobile suspension system, realize the effective control of the suspension system, and thereby improve the stability and safety of the car body, this paper takes the active suspension as the research object, establishes a two-degree of freedom one-fourth suspension model, and a suitable mathematical model is established by force analysis. In addition, based on MATLAB/Simulink, a simulation model was——is established. By selecting the most effective standard of vehicle body acceleration as the control target, a PID controller was built to carry out simulation regulation. Finally, the parameters are adjusted by trial and error method, and the optimal tuning results of PID controller parameters are obtained through multiple simulation.

Abstract:In this paper, a parallel algorithm combining MATLAB and OpenACC is proposed for the complex programming problems of current CUDA-based median filtering parallel acceleration algorithm and the cumbersome implementation of image data extraction and display. The algorithm uses MATLAB to extract the image and converts it into an array file. Then it uses the OpenACC language to convert the serial code to the parallel code and processes the array file converted by MATLAB. Finally, the filtered data is displayed as an image through MATLAB. The acceleration experiment of the median filtering algorithm is carried out by simulation experiments. The experimental results show that the proposed algorithm accelerates the algorithm faster than the serial program in the case of greatly reducing the amount of code conversion workload. And it is equivalent to the effect of CUDA acceleration.

Abstract:This paper applies the uncertainty theory to the time-cost trade-off problem due to various uncertain factors in real project. In practice, the overlapping relationships among some activities usually exist in the project. In order to simplify the calculation, the relationships are converted into the delay time and introduced to the formula of the project time. Then, the uncertain time-cost trade-off model with delay time is built. Meanwhile, the equivalent form of the uncertain programming model is given and proven to solve the proposed model. Finally, a project case is used to illustrate the effectiveness of the proposed model.

Abstract:In this paper, the combination of experimental and finite element software simulation is used to analyze the bending resistance of steel-concrete composite cross-section thin steel composite pipe beams with different interlayer concrete strength. The outer layer is made of thin-walled stainless steel pipe, the inner layer is steel pipe, and the three test pieces of concrete strength grades C20, C40 and C60 are respectively sprayed in the middle of the double-walled pipe, and the test pieces are loaded by the grading loading method, and the test results are limited. The results of the meta-software simulation are consistent. The results show that with the increase of concrete strength, the flexural capacity of the specimen and the ductility increase, and large plastic deformation can occur to absorb energy. The test results obtained can provide a basis for future research.