Abstract:To derive a rigorous solution for undrained expansion of cylindrical cavity， the modified Cam-clay model of structured loess was employed to describe the mechanical properties of loess. The small deformation assumption was used to solve the soil stress and deformation in the elastic zone around the cavity. Besides， the boundary value problem of cylindrical cavity expansion can be transformed into three first-order nonlinear ordinary differential equations with the stress component as the basic unknown quantity in the plastic region. The governing equation was solved by using the stress component on the elasto-plastic interface as the initial condition to obtain the stress distribution in the plastic zone around the cavity， then the pore water pressure was derived by integrating the radial equilibrium equation. The correctness of the method in this paper is verified by parameter analysis. The results show that the degenerate solution is completely consistent with the existing numerical solution， and the soil structure has a significant effect on the stress component， the specific volume， the excess pore water pressure， and elastic-plastic radius.

Abstract:Based on the singularity and non-convergence characteristics of the Jacobian matrix， the composition and the algorithm of the elasto-plastic constitutive model were comprehensively analyzed. The problem of solving the highly nonlinear equations in Newton-closest point projection method（Newton-CPPM） implicit algorithm was transformed into a seeking minimum value problem by the conjugate gradient method， and the improvement of traditional implicit method was eventually accomplished. Finally， according to the calculations of single unit， the Saniclay model considering the structural properties of soft soils was set as an example， which is involved in different strain paths and initial stress states. In this process， the calculation convergence， the accuracy and the efficiency between traditional implicit algorithm and improved implicit algorithm were separately compared. In addition， the differences between traditional and improved implicit algorithm were examined by engineering example. Results show that， compared with the traditional implicit algorithm， the improved implicit algorithm can effectively improve the computational efficiency and convergence.

Abstract:Based on the Badaling Great Wall Station of Beijing-Zhangjiakou High-speed Railway， the dynamic and static stresses of variable-section lining trolley of super-large section tunnel were studied， and the effect of cross-sectional changes on the trolley structure was analyzed. Numerical simulation was used to analyze the static stress characteristics of the trolley structure， and the field monitoring was used to analyze the dynamic stress characteristics of the trolley structure and the influence law of cross-sectional changes on the stress of the trolley structure. The results show that： the static stress and the displacement of the trolley structure are unevenly distributed， and each structure is variable， with some structures showing obvious stress concentration. During the pouring process， the stress is larger on the outside and smaller on the inside； the stress value is the largest when the trolley pouring area is located above the supporting structure， and the stress of the trolley structure is basically constant during the concrete solidification process. As the cross section of the trolley becomes larger， the stress of each trolley structure increases. The arch shoulder screw is the member with the greatest change in stress.

Abstract:In view of the effect of random pitting corrosion on axial bearing capacity of circular steel pipes， the changing rule of bearing capacity was revealed along with the mass loss ratio. A reduction factor was introduced to investigate the effect of corrosion thickness， pitting size， steel grade and wall thickness of steel pipes. The analytical formula for predicting the reduction factor was proposed. This formula can exactly predict the reduction factor of corroded steel pipes which is affected by random pitting corrosion.

Abstract:A parametric data-exchange method for solid model is described based on industry foundation class （IFC） standard aiming at the defects of previous technique such as lack of parameterization level and severe information losses. A basic framework of IFC formate file is put forward， and specific data-exchange methods for all kinds of information of solid model are respectively studied and successfully applied by programming. The software test results show that the parametric data-exchange method could correctly describe the complex solid model and the output IFC formate files can be correctly opened and edited in main building information modeling （BIM） platforms.

Abstract:An intelligent decision-making system for the environment in road tunnel was established based on virtual reality （VR） technology. Driving simulation experiments were carried out at different color temperatures to establish a measurement model between the growth rate of attention and the color temperature of light source， and the distribution of reaction time was given. The results show that at the entrance and exit of the tunnel， drivers’ attention growth rate is higher and drivers’ attention reaches the lowest level after driving about 1 200 m. The color temperature of different light sources has a significant difference in the effect on drivers’ attention. The color temperature of 6 300 K is the best for the concentration of attention resources. Under low color temperature （2 000?4 000 K）， the driver’s reaction time to the accident is about 0.78 s， while under medium and high color temperature （5 000?8 000 K）， the driver’s reaction time to the accident is about 0.58 s.

Abstract:According to the contrast principle of ambient light intensity for disability glare， a process of disability glare analysis based on three-dimensional spatial relationship model is proposed. Taking same-layer arranged highway and railway on the lower deck of a cable-stayed truss bridge as the engineering background， a case study is carried out. When no glare-resistance measures are taken for parallelly arranged highway and railway in close range， the glare effect produced by headlamps of railway train is serious， which is far beyond the threshold requirements of the relevant codes. Finally， an assemblable and three-dimensional glare-resistance strategy is proposed， and a detailed glare-resistance scheme is given in the case study. The results show that the glare-resistance strategy proposed can effectively reduce the glare effect of railway train headlamps to the drivers on highway.

Abstract:Based on the portal landscape design scheme of Ban-lun Tunnel in Yunnan Province， we selected four primary influencing factors including portal linetype， portal color， portal greening， and portal texture. An orthogonal experimental design was adopted， and nine model schemes were established. A driving simulation test was conducted using a driving simulation test system and eye tracker， meanwhile， the pupil diameter and the sight deviation time were selected as evaluation indexes. The results show that in terms of portal landscape driving comfort， the order of importance of the four factors is as follows： portal texture， portal greening， portal color， and portal linetype. The distractions of drivers appear in the fifth model （green end wall， mural， city wall type， and natural greening）， and the ninth model （grey end wall， mural， arc line type， elaborate greening）， leading to the potential safety hazard of driving. Based on the experimental results， some optimization suggestions were put forward for the tunnel portal landscape design from the aesthetic aspect.

Abstract:Based on driving simulation experiments， the speed and lateral offset data of 15 drivers in 72 curve sections with the radius of 100?500 m were collected， and the effects of spiral length on vehicle speed and trajectory on two-lane highway were analyzed. The results show that under the condition of a certain radius， with the increase of spiral length， the speed difference is on the rise， while the speed gradient is on the decline. With the increase of spiral length， the fluctuation amplitude of vehicle trajectory increases， while the fluctuation frequency of vehicle trajectory decreases. When the radius is 100 m， the local curvature of vehicle trajectory will increase if the spiral is too short. For the curves with the radius of 200 m， the local curvature of vehicle trajectory will increase if the spiral is too long or too short. For the curves with the radius of 300 m or more， the length of spiral is positively related to the maximum local curvature of driving trajectory.

Abstract:The traffic capacity model based on expected headway time was established. According to the characteristics of urban underground interchange， the traffic capacity of main road， ramp section， merge area and diverge area in urban underground interchange was calculated， and the recommended values were given. Finally， the accuracy of the model was verified by the measured data. Study results show that， the traffic capacity of each underground interchange is reduced compared with that of ground interchange. The main road is reduced by 8%?11% （near 10% on high-speed section）， the ramp section is reduced by 14%， the ramp merge area is reduced by 10%， and the ramp diverge area is reduced by 11%.

Abstract:By using an array of spring elements to simulate the support condition under airport concrete pavement slab， a numerical simulation model was developed to study the variation of aircraft-induced strain under poor support conditions. The different aircraft loads and load transfer states at joints were considered. A full-scale experiment was conducted for model verification. As indicated in the results， the spring-based method that simulates the support condition performs well on solving the mechanical responses. Support-loss would increase the tensile strains at the edge of support-loss region， and the location where critical tensile strain occurs would be transferred from the bottom to the top of the pavement. When the critical tensile strain under poor support condition exceeds the maximum tensile strain under intact condition， the support condition was determined as the critical support condition. Compared with the conventional evaluation methods of support condition （e.g. deflection-based methods）， the critical support condition can reflect the effect of support-loss more accurately.

Abstract:Lincomycin and three macrolide antibiotics （erythromycin， spiramycin， azithromycin） are widely used in medical， livestock and poultry industries， and distributed to the environment through the discharge， treatment and disposal of pharmaceutical wastewater， livestock wastewater and municipal sludge. Anaerobic digestion is a common method to effectively treat antibiotic wastewater. In view of the concentration distribution of these antibiotics in typical wastewater and their effects on anaerobic digestion and metabolism， the response characteristics of anaerobic digestion to these four antibiotics were summarized. The results show that lincomycin and three macrolide antibiotics can promote the anaerobic digestion of methane at low concentrations but inhibit the methane production at high concentrations. The inhibition effect is mainly caused by the accumulation of volatile fatty acids（VFAs） and the decreased activities of some VFA-oxidizing bacteria and methanogens. Finally， the anaerobic metabolic biodegradation pathway of the antibiotics and the method of relieving the antibiotics caused inhibition were discussed.

Abstract:Twenty-five popular landscape trees in Shanghai were selected and seven indicators of victimization， chlorophyll， electrical conductivity， specific leaf mass， net photosynthetic rate， malondialdehyde and proline content were measured in the flood simulation experiments. Then， the resistance spectrums of the 25 landscape trees were scheduled. Finally， a method for predicting the resistance of landscape trees via the level of photosynthesis was put forward， giving priority to chlorophyll， specific leaf mass and net photosynthetic rate indicators. According to the level of waterlogging resistance， 25 tree species were divided into four types： strong waterlogging resistance， relatively waterlogging resistance， general waterlogging resistance and weak-waterlogging resistance.

Abstract:Aiming at the limitations of model-based and rule-based fault diagnosis methods， a data-driven fault diagnosis method for transmission sensors was proposed. First， a residual sequence was obtained between the output of actual sensor and the output of sensor model established by step-wise regression. Then， the residual sequence was decomposed by wavelet packet transform（WPT）， and the Shannon entropy of each node was calculated as the feature values. Finally， a probabilistic neural network（PNN） was adopted to identify the feature values of different sensor faults. This method is verified by transmission signals from hardware-in-the-loop platform. Results indicate that the method has a diagnostic accuracy of 98.50%， and the diagnostic accuracy varies little under different sample divisions. In addition， the fault diagnoses of two speed sensors were also performed， and the diagnostic accuracy is at a relatively high value， which proves the applicability of the method.

Abstract:In view of the acoustic coupling between rubber thin layers and a cavity， an analytical model for structural-acoustic coupling was proposed， and the material and geometric parameters of sealing strip were optimized based on the model. The acoustic modal shape function of the cavity was obtained by adding an auxiliary cosine function. By employing the Rayleigh-Ritz method， the analytical model was established for the structural-acoustic coupling between the vibrations of simply-supported layers and the coupled cavity. The analytical model was used to calculate the mean square responses of a double-wall model under single-point force and the sound transmission loss under a diffuse acoustic field， respectively. The accuracy of the model was verified by comparing with the results of the impedance-mobility method and the numerical method of hybrid finite element-statistical energy analysis （FE-SEA）. The results show that： the proposed method has higher computational efficiency than the FE-SEA method； the analytical model and particle swarm algorithm can optimize the material and geometric parameters so that the sound insulation can be improved by more than 10 dB； the optimized sealing strip tends to have a flat and wide cross-section.

Abstract:Hospitals are the core department in the fight against the covid-19 pandemic. The effective management of hospital user activities and the increasing space utilization have become urgent problems. The concept of flexible space was employed to analyze the characteristics of hospital user activities and space use in the method of space use analysis. By constructing a hospital user activity-space mapping process， the hospital spaces that initially designed for meeting a single activity of one type of user can be transferred to the hospital spaces for meeting the activities of multiple types of users. Finally， the conformity and the acceptability of the method are verified in case study.

Abstract:Social income distribution and inequality problems have received widespread attention from society and scholars. But very few studies have analyzed how the distribution of social income affects the market penetration process of new technologies or new products. By a dynamic theoretical model and an empirical analysis， it is found that although the large gap between the rich and the poor is conducive to the introduction of new technologies at the beginning， but because the wealth is highly concentrated in the high-income class， the other classes cannot pay the high prices of new technologies， which inhibits the application of new technology or new products. When formulating relevant policies to support new technologies， the government should give some consideration to the current income distribution of the society， so as to maximize the effect of policies.