Abstract:For the foundation boundary approximation in the vibration analysis,dynamic responses of foundation treated by fixed boundary,equivalent viscoelastic boundary and infinite element boundary were obtained by using the finite element method. Operability and accuracy of various boundary methods were analyzed according to the measured data. The results show that both the equivalent viscoelastic boundary and the infinite element boundary can better reflect boundary vibration characteristics,but infinite element method has a better advantage in terms of accuracy.

Abstract:According to the analysis method by Lizheng software and actual pit control variables to analyze and calculate the optimal solution,the results of horizontal displacement of the scheme are obtained. By changing the diameter of the pile,we can analyze and calculate the detailed parameter scheme that can be more economical under the premise of safety requirements and specifications. Then,the optimal scheme is simulated by finite element method,and the displacement analysis and settlement analysis are carried out to verify the rationalization. Conclusion:with the increase of excavation depth,the settlement of pile increases at first and then decreases,while the settlement of soil decreases gradually. The horizontal displacement of the pile and soil is uniformly distributed from top to bottom,and then the maximum horizontal displacement occurs at the top of the pile.

Abstract:In order to study the microstructural mechanism of Shanghai soft soil under consolidation,the fourth layer of Shanghai soft soil under different consolidation pressures were tested by high resolution field emission scanning electron microscope. The results show that with the increase of consolidation pressure,void ratio decreases significantly during the initial period,and the soil density increases. Average form factor increases significantly,the smooth degree increases significantly. The probability entropy decreases gradually,the orientation and order of pore arrangement are enhanced. Consolidation pressure changes pore characteristics including scale,pattern and arrangement significantly,and the microstructure parameters can preferably reflect the macroscopic mechanical properties.

Abstract:With the expansion of the scale of underground engineering construction,it becomes an important issue about seepage failure hazard of fractured rock mass in engineering and theoretical circles. Developed with simulated rock rough single fracture specimens of different rock joint roughness,laboratory tests of non-Darcy seepage in rough single fracture with variable apertures and high hydraulic gradient are carried out. It is indicated that flow behavior in the rough fractures becomes nonlinear with the high seepage velocity,and the hydraulic gradient and volumetric flow rate data points are fitted very well by the Forchheimer equation. A semi empirical formula of the non-Darcy effect coefficient is presented,which provides an important reference for the prediction of water bursting in engineering practice.

Abstract:The shear strength of compacted loess is an important factor which seriously influencing the stabilization of the high loess-filled project. In order to study how the compaction degree and water content influence the shear strength,a series of direct shear tests with different initial compaction degrees and initial water contents are carried out for compacted Q₂ loess and Q₃ loess in Yan'an new district. Then,a preliminary discussion is conduct to find out the shear strength difference between compacted loess from backfill and samples prepared in laboratory. The results show that cohesion and internal friction angle increase with the increase of compaction degree, the clay content in compacted loess has a great influence on the cohesion and internal friction angle. Cohesion,internal friction angle and shear strength decrease with the increase of water content,and compacted Q₂ loess is more sensitive to water. The shear strength of compacted loess from backfill is much higher than samples prepared in laboratory.

Abstract:In order to discuss and investigate the influence of the angle of inclination on the crack initiation,propagation and damage,the extended finite element method in the ABAQUS platform is used to simulate the semi-circular surface cracked rock mass with different angles. The results show that with the increase of fracture inclination,the peak strength of crack increases. The angles of cracks have magnificent impact on the surface cracks. Moreover,theⅠ type stress intensify factor plays an important role in the process of crack propagation.

Abstract:Comprehensively considering the erosion of red soil slope with herbaceous vegetation,indoor simulated rainfall experiments are carried out to discuss the anti-erosion effect with different slopes and different vegetation coverages of red soil slope in heavy rainfall(2.0 mm/min)and short duration(30 min). The results show that with the increase of vegetation coverage,the erosion reduces rapidly within the vegetation coverage less than 40% while the erosion reduces gently as the vegetation coverage more than 60%,so the critical vegetation coverage is 40%-60%;The critical slope changes for different vegetation coverages,The critical slope reduces within the vegetation coverage less than 40% while The critical slope disappears as the vegetation coverage more than 60% because the erosion increases gently. The reason led to this phenomenon is that the critical slope can be effected by soil properties,vegetation coverage,rainfall and so on.

Abstract:In order to know the regulation of crack evolution,dry wet cycling test taking hefei expansive soil as the research object is carried out to study the expansive soil crack evolution under rainfall evaporation. The image recognition program is used to quantitatively analyze the crack rate of the area and observe the shape and depth of the lateral fissure. The results show that in the case of single dehumidification,the area crack rate,fracture fractal dimension and other morphological parameters and fissure depths gradually increase with dehumidification time,and the soil surface morphological parameters have the limit value. The wet cycle is characterized by repeated cracking and healing of fissures,which tend to loosen the soil structure,and the crack rate and fissure fractal dimension tend to be stable. The lateral slope instability is caused by lateral fracture development through lateral profile observation.

Abstract:In order to study the effect of limb length ratio on the mechanical properties of Reinforced Concrete L-shaped Columns Strengthened with CFRP cloth,numerical simulation of ABAQUS with different limb length ratio is carried out. The obtained test parameters are analyzed,and the result shows:with the increase of limb length ratio,the ultimate bearing capacity decreases;the reinforcing effect of CFRP cloth on L-shaped reinforced concrete columns with larger limbs is obvious. The larger the ratio of the limb length,the larger the bearing capacity is. The tensile properties of both CFRP cloth and steel bar in the tension zone also play a full role.

Abstract:In view of the deformation field measurement problem of steel truss node,in this paper,we carried out a certain coal conveying trestle steel truss node test and performed displacement measurement by using the digital close-range photogrammetric technology. Firstly,we took fixed-point shooting method to obtain the deformation image. Secondly,we conducted the image pre-processing and the pixel coordinate extraction. And finally,we analyzed the displacement change rule of the measurement point. The results show that the measurement accuracy from the close-range photogrammetric technology can meet the needs of the whole deformation test of steel truss node experiment,and the close-range photogrammetric technology has characteristic of simple operation and strong practicability.

Abstract:In this paper,the recycled coarse aggregate was prepared from waste concrete and brick,in which the waste concrete coarse aggregate was substitute for waste brick aggregate with 0%,10%,15% and 30%. The damage of recycled concrete was detected by ultrasonic wave,and it was measured by the decay of the ultrasonic wave velocity. The ultrasonic experiment was carried out on the recycled concrete specimen under uniaxial compression load condition. The effect of uniaxial compressive stress on the damage of recycled concrete under different replacement rates of waste bricks was obtained through experiments. The results present that the replacement rate of waste bricks has a great effect on the damage of recycled concrete under uniaxial compression. Finally,for the uniaxial compressive stress coefficient,which is the main factor affecting the damage of recycled concrete,the damage relation model of recycled coarse aggregate concrete containing brick is established.

Abstract:The granulated blast furnace slag can be used to replace partial sand(extra fine sand) to prepare concrete. The influence of different rates of slag replacing partial sand on the properties of concrete is studied. The results show that the fluidity of concrete containing granulated blast furnace slag decreases with the increase of slag replacement rates. With the increase of slag replacement rates,the compressive strength of concrete increases at first and then decreases,optimal levels of granulated blast furnace slag replacement rates is 60%. The granulated blast furnace as fine aggregate has positive effect on the later strength of concrete. Meanwhile,based on the test results,the formula to predict the compressive of granulated blast slag as fine aggregate concrete is proposed.

Abstract:In order to explore the vibration characteristics and vibration transmission characteristics when the train passing through the viaduct of urban rail transit,taking an urban rail transit viaduct as the research object,the vibration test is carried out at different distances from the pier. The test results are analyzed in frequency domain. Then,the 1/3 octave are analyzed by using linear weighting and Z weighting,and the transmission characteristics of vibration under characteristic frequency are analyzed when two weights are adopted respectively. Finally,the transmission characteristics of equivalent continuous Z vibration level are analyzed. The results show that when the train passes through the urban rail transit viaduct,the vibration acceleration of the ground is mainly distributed in the 0~200Hz frequency range,and the peak value of vibration acceleration is mainly distributed in the frequency range of 60~80Hz. Under the linear weighting,the global peak of the vibration acceleration level of the ground appears at the frequency of 63Hz,and the local peak appears at the frequency of 4Hz. Under the Z weighting,the global peak value of the vibration acceleration level of the ground appears in the range of 50~63Hz,and the local peak values appear at the frequency of 4Hz. With the increase of the distance from the center line of the track,the acceleration level of the ground vibration decreases with the increase of the distance from the center of the pier to the ground,and the attenuation rate decreases with the increase of the distance from the center line of the track.

Abstract:The prediction accuracy of subgrade settlement is not high and the applicability of prediction method is not strong. Based on the combination forecast theory,with the help of MATLAB software,GM(1,1)-Hoshino Nori combination forecasting model is proposed. This model is based on the grey theory GM(1,1) forecasting model linear combination model and Hoshino Nori settlement prediction,taking the combination forecasting error square as standard to determine the weight coefficients of two kinds of prediction methods and minimum standards. With the Guangdong highway construction period and operation period of subgrade settlement data,GM(1,1)-Hoshino Nori combination forecasting model prediction results are better than the two methods separately predicted results. The present method has higher prediction precision,stronger engineering application.

Abstract:In order to solve the problem of roadbed packing in Linzhi area of Tibet,the silt is improved by cement in the area. The maximum dry density,the optimum water cut rate,the CBR value and the physical properties of the modified soil under different freezing and thawing cycles are studied by the compaction test,the CBR test,the unconfined compressive strength test and the frost heave sedimentation test. The results show that:The optimum moisture content of cement with different content is almost constant,and the maximum dry density increases slowly with the increase of content;Under the action of freeze-thaw cycle,the cement improved silt is still brittle failure mode,and the uniaxial stress-strain curve of the cement-modified silt is almost coincident,so in the actual project the strength of the cement frozen after 5 times can be taken as a modified soil design reference strength;Considering the effect of freeze-thaw cycle,the optimal cement content of the silt filler on the secondary road of Linzhi deep silty area in Tibet is more than 4%.

Abstract:In order to study the steel bridge pavement shear failure behavior,the 3D discrete element model of steel deck pavement composite structure was established by using discrete element method. The meso parameters of asphalt mortar under 30℃ and 60℃ were calculated by using the Burgers model parameters obtained by DSR test. The interlaminar shear behavior of steel deck pavement under 30℃and 60℃ was simulated and compared with the results of laboratory shear tests. The bond failure between the steel deck pavement and the crack development is analyzed. The results show that the interlaminar shear behavior is simulated well by using the discrete element method. The cracks appear when the bonding between the aggregate unit and the steel plate unit begins to fail,and develop gradually along the interlayer with increasing shear displacement,and finally run through the interface between the steel plate and the pavement. The integrity of the pavement is basically maintained because the bonding failure mainly lies between the steel plate and the pavement layer and there is no bonding failure between the units in the pavement.

Abstract:In order to provide basis for seismic research of the tower of long-span suspension bridge,the longitudinal damage characteristics of the tower of long-span suspension bridge under earthquake action is explored. A finite element model is established used ADINA by taking a long-span suspension bridge as the example and the development characteristics of plastic damage of the tower is observed by 20 earthquake excitations with increasing intensity in the longitudinal direction. It is found that with the increase of earthquake intensity,the development of the plastic damage at the bottom of the tower and in the middle of the tower bottom is synergistic. However,the rate of development of the plastic damage at the bottom of the tower is far greater than that in the middle of the tower,which leads to the low level plastic damage degree in the middle of the tower when the final section fails at the bottom of the tower.

Abstract:In order to reduce the monitoring section settings without affecting the water pollution control,the SPSS clustering analysis is used in this paper. This paper is based on monitoring data of eight monitoring sections of Fuyang River and the spss cluster analysis is used to cluster five water quality indexes,such as COD,ammonia nitrogen and so on. This paper also makes a brief analysis of water quality variation on some monitoring sections. The results show that eight monitoring sections are divided into three categories. Thereby,this paper determines the affinities between the monitoring sections. It implied that clustering analysis can play a very good role in categorization analysis of multiple monitoring sections and water pollution control of Fuyang River.

Abstract:The previous batch experiments have verified that three kinds of aquatic plants(Myriophyllum,Ceratophyllum and Potamogeton pectinatus)can obviously absorb and decompose the nutrients and pollutants in water body. In order to further verify the treatment effect of the selected aquatic plants' combination on the actual polluted water,a plant fence was established to study the removal of the nutrients in polluted water under in-situ conditions. The results showed that the combination of aquatic plants in the fence could remove the pollutant in water under in-situ conditions. Compared to the control group,the combination of Myriophyllum and Ceratophyllum showed the best removal effect of nitrogen nutrients,the combination of Potamogeton pectinatus and Myriophyllum showed the best removal effect of dissolved phosphorus nutrients in the water,while the combination of grate tooth eye and the fox tail algae showed the best removal effect of the dissolved COD_Mn. In a comprehensive view,the combination of the Fox tail algae + Ceratophyllum is the best for the removal of nutrients.

Abstract:Aiming at the problem of heat transfer and mass transfer of wet air and spray water,hawse did some research on basic theory,phenomenological equation and experimental analysis. First of all,based on the irreversible thermodynamics theory,combining with the basic law,we established a system of phenomenological equations describing the heat and mass transfer. Secondly,the water and air influence law of inlet spraying water and air at different temperatures was analyzed by the phenomenological equations. It is found that under the condition of this experiment research,the theoretical model is basically reliable and the result is consistent with the change of the parameters of the actual project. It can be used to analyze the heat and mass transfer of wet air and spray water.

Abstract:Detailed analysis and research on the characteristics of Chaheji river catchment distributary channel sand body and its effect on development are carried out. According to statistics of sand bodies by drilling,the subaqueous distributary channel sand body of Chaheji oilfield has small vertical thickness and narrow width. The thickness of single sand body distributes between 1-5 meters,and the river width is generally less than 100 meters. Sand body and oil sand body can be added by infill drilling,and connectivity of sand body and oil sand body is also increased. However,even well spacing reduces to 100 meters,the degree of control pattern to the sand body is still low. Most of the oil sand bodies are difficult to form the injection production relation,appearing the phenomena like production and no injection or injection and no production. The injection-production relationships of oil sand body mainly are two point and three point of injection production system. It is difficult to form a perfect injection-production well pattern system. The multiple direction effect relationship between oil wells and water wells is illusion,mainly due to the development of composite layer. Affected by the sand body characteristics,the types of remaining oil include mainly lenticular oil sand body with no control of the existing well pattern,remaining oil of production with no injection by elastic development,remaining oil by one-way water flooding etc.

Abstract:Gear's grids are divided by using finite element pre-processing software Hypermesh,and ANSYSWorkbench is applied to analyze gear's meshing static contact mechanical features. Based on the tooth flank static contact mechanical analysis,we worked out cone gear's stress change and stress deformation finally. The contact performance of gear is analyzed by invented rolling test,which is consistent with flank static contact mechanical analysis,it's further verified the correctness of the static analysis.

Abstract:The maximum graphite size in cast irons with different volumes was predicted by the method of statistics of extreme value(SEV),and the fatigue strength was further predicted by utilizing the result of SEV. It is shown from this study that with increasing the predicted volume the sizes of the maximum graphite increase,while the fatigue strength decrease.

Abstract:In this paper,an accurate micromagnetic model is built for CoPt-TiO₂ (6 nm)/Co-TiO₂(δ=1~4 nm) exchange coupled bit pattern media,based on the polycrystalline microstructure,to investigate the effect of the magnetic parameters such as the thickness,the anisotropy,the saturation magnetization of the soft layers on the coercivity of the bit pattern media. It is found that:the coercivity decreases from 8.2 kOe to 5.8 kOe when the thickness δ of the soft layer increases from 1 nm to 4 nm,whereas the normalized Mr remains 0.99. Meanwhile,the coercivity decreases when the anisotropy is lower,the saturation magnetization is larger in the soft layer and the angle θ is larger in the hard layer.