Abstract:In order to explore the impact of culvert on the roadbed-culvert transition section in deep seasonally frozen region, a finite element model was established to simulate culvert’s temperature fields considering latent heat, and judged the reliability through comparing the simulation results with the existing monitoring data. Models of different parameters or different sizes were stimulated to investigate the influence on the maximum frozen depth. The results indicate that: 1) The measured temperatures and simulated temperatures agree well which demonstrated the accuracy of the numerical model. 2) In the design of culvert in seasonally frozen region, foundation convection under the culvert in cold season could not be ignored. Some active measures should be taken to protect the subsoil from the effect of convective heat transfer. 3) The culvert maximum frozen depth changing with the amount of water content is divided into three steps. At first, it decreased with increasing water content. And then, the reduction got slow, even the frozen depth increased slightly. At last, it decreased again; 4) The diameter of culvert greatly affected the maximum frozen depth, while the size of clear height had little effect on it. Diameter is priority for the requirements of strength, stability, functionality, etc. and the clear height could be considered at last.

Abstract:In conventional indirect evaporative cooler, the lack of uniformity and integrity of water film surface results in low thermal efficiency. To solve the problem,an indirect evaporative cooler with rotating water on both sides is put forward. The experiment was carried out to explore the heat transfer performance of heat exchanger under three types of arrangement and the factors influence the performance were studied by orthogonal experiment. The study results show that when the hole is on the direction of air flow, the thermal performance of heat exchanger is optimal and the recommended rate of rotating water distribution installation 76 r/min. Heat exchange increases with the increase of water spray quantity, air velocity, cooling water flow rate, cooling water inlet temperature and decrease with increase of water temperature, air temperature cooling water inlet temperature has the most significant effect on the performance of heat transfer. And when the temperature increases form 35 ℃ to 39 ℃, the heat transfer improved 37.62%, Heat transfer in per unit area is about 1.14 kW. The heat exchanger can be installed in exhaust tunnel of underground stations, which can effectively solve the subway station cooling tower installation location problem.

Abstract:A new ceiling radiant cooling panel(CRCP) with a uniform temperature distribution in the surface was introduced, by analyzing the physical structure and heat transfer mechanism of CRCP. A mathematical model of the radiant heat transfer process was established, through which the cooling capacity of CRCP was calculated using MATLAB. Compared with the results of thermal performance test, the mathematical model was reasonable with a maximum error less than 6%. According to the results of model and experiment, in the constant flow condition, due to the air in the sandwich structure, cooling capacity of CRCP decreases as the temperature drops. Limited by the chilled water temperature, the temperature of CRCP usually is in range of 18~20 ℃. Based on the experimental ，the distribution of relative humidity and the temperature in the room and cold load undertaken by convection and radiation respectively in the room were also studied, aiming at providing some relevant basis for the application of CRCP system.

Abstract:The natural ventilation in a novel built-in photovoltaic-Trombe wall (BiPV-TW) was numerically simulated by CFD method. The effect of solar radiation, channel width and height on the air flow pattern and ventilation rate was analyzed. Results show that the solar radiation, channel width and height influenced the ventilation rate remarkably. As the solar radiation and BiPV-TW height increased,the ventilation rate increased. As the channel width increasing from 0.1 m to 0.4 m, the ventilation rate monotonously increased. However, when the channel width exceeded 0.5 m, the reverse flow was formed in the top zone and the ventilation rate decreased. A maximum air volume flow rate was achieved when the channel width was approximately equal to 0.4 m in a 3 m height model. The channel width was the dominant factor that influenced the flow pattern in the channel. When the channel width was smaller than 0.4 m, the airflow was thermally stratified laminar flow. When the channel width exceeded 0.5 m, thermally stratified flow disappeared due to the reverse flow formed in the top zone and the laminar flow became turbulent.

Abstract:Thermal environment is analyzed based on the field measurements of indoor and outdoor temperature and humidity of a typical Tibetan traditional dwelling in a village of Gannan Tibetan Autonomous Prefecture, Gansu province in winter and summer. Results show that the combination of local factors such as history, geography, climate, unique local-style dwelling houses building structure and monomer structure. The structure (envelope)of traditional Tibetan dwelling has a good thermal performance. Passive methods should be used to build thermal environment constructions. Further improvement for indoor thermal comfort conditions through comprehensive and energy-saving heating are needed.

Abstract:The building embodied stage is the LCA research focus due to large and intensive CO2 emissions. In order to establish the CO2 emissions calculating model during the embodied stage, CO2 emissions load in the process of building materials, equipments manufacturing, transporting and construction should be included. CO2 emissions during building embodied stage of 78 office buildings were analyzed by this model. On average, the amount of carbon emission during embodied stage is 326.75 kg/m 2. The carbon emission in per unit area increase with the growth of building height and that of super high-rise buildings is 1.5 times as much as multi-story buildings. Carbon emission of civil work accounted for about 75% of the total amount during embodied stage, and the carbon emissions of rebar, concrete, mortar and wall materials accounted for over 80% of the carbon emission of civil work. According to the statistic of prediction model dependent on building story and amount of building materials,the CO2 emissions during building embodied stage could be precisely predicted on basis of the independent variablesincluding concrete and wall materials respectively.

Abstract:Isotropic and anisotropic porous medium with the same porosity, different pore size distributions and pore surface fractal dimensions were constructed by random growth method, and the impact of microscopic pore structure on moisture migration process in pores of porous medium was theoretically studied. The results show that the internal transport properties of porous medium are not only determinded by porosity, but also greatly influenced by pore size distribution and pore surface fractal dimension. The biggest water vapor diffusion concentration differences of three kinds of isotropic and three kinds of anisotropic porous medium with the same porosity, different pore size distributions and pore surface fractal dimensions are 30.6% and 23.3%, respectively. Better water vapor diffusion properties in pores of isotropic porous medium demands for bigger tiny pore size distribution rate and larger pore surface fractal dimension, which means the pore connectivity is better. While better water vapor diffusion properties in pores of anisotropic porous medium(water vapor diffusion direction is perpendicular to the direction of larger growth rate of anisotropic porous medium) demands for more big pore size distribution and smaller pore surface fractal dimension. The method lays a theoretical foundation for preparing indoor humidity control of building materials.

Abstract:Occupant’s thermal adaptation to free-running environment of apartments in summer was studied at an individual level.The relationship between indoor environmental parameters and occupant’s thermal sensation to indoor environment has been developed. Moreover, the effects of indoor temperature and relative humidity, as well as the interaction effects of the two parameters on occupant’s thermal sensation have been analyzed. On this basis, the characteristics of occupant’s adaptation to indoor temperature and relative humidity have be identified simultaneously. One particular individual dweller in Beijing has been selected to study the thermal adaptation by applying the method to practice.

Abstract:Thermal environment in urban public space is considered as an important factor affecting thermal comfort of human beings. In the whole year, thermal environment in public space of the city in hot-summer and cold-winter zone changes dramatically, which has an effect on human thermal comfort. In this study, three typical public spaces including street, park and square of Changsha were selected for a long-term experiment of thermal environment. Based on the analysis of four significant thermal environment parameters-air temperature, relative humidity, global temperature and wind speed, seasonal characteristics of thermal environment in urban public space were obtained. The results show that the characteristics of urban thermal environment are determined by natural climate, while the physical structure of a city has essential impact on the changes of local outdoor thermal environment. Affected by plants (trees) and water (Xiangjiang river) air temperature of the street along the street is much lower, relative humidity is higher and solar radiation is weaker in most of the year. Compared to the street along the river, air temperature of the square is higher and solar radiation is stronger.

Abstract:The acoustic environment of highway tunnel is complex and has influences on the driving safety and comfort. In case of emergency, evacuation information is difficult to transfer. Finite element method is used for calculating highway tunnel acoustic modal and attenuation characteristics. The results show that acoustic mode of highway tunnel has symmetry in the horizontal pressure amplitude of symmetry regional is equal and phase is the same or opposite. The higher modal frequency, the greater sound pressure amplitude is, and the effect of tunnel length on modal frequency is smaller. Decay curves of pressure level at each point in the highway tunnel over time are nonlinear. After the source excitation, in 1.5 s, attenuation rate is faster than that of few seconds later and the attenuation time of sound pressure level 30 dB is 5.5 to 7 s.

Abstract:energy saving potential of latent heat storage unit was studied(LHSU) by using neural network. Experiments were conducted in an enthalpy difference laboratory to simulate the performance of LHSU. Different neural network structures were built to predict the influence of nonlinear factors including air flow rate, air temperature. Coefficient of performance (COP), energy storage and discharge rates on the unit’s operation performance. Results showed that the predictions agreed well with the experimental data with correlation coefficients in the range of 0.99~1.00, mean relative errors below 2% and very low root mean square errors.

Abstract:Current mainstream lighting type from three aspects includingcomfort，energy efficiency and visibilitywas analyzed as well as the shortcomings of the lighting type. The LED fails to improve the current condition effectively and the replacement of HPS with LED is not advisable. To avoid glare, it is necessary to locate road lamp between driver and road surface. Light distribution should be redesigned and the increased proportion of effective lighting is required to improve the visibility level. A new method is proposed by employing separate, low-power and high efficacy LED and customized control system to satisfy the requirement of various functions including road surface lighting, space lighting and lighting in the fog condition

Abstract:Generally, lighting designs originated from designer’s experience, and the lack of understanding spectrum and landscape formation results in unexpected effect, like discrepancies of lighting and landscape, excessive lighting, light pollution, etc. Based on spectrum theory, relationship between illuminant color and object color had been discussed, and through taking an object color sample as a reference, lighting effect of traditional light sources, LED light source and a variety of monochromatic spectrum light sources had been studied. Effect of light sources’ spectrum on environment had been analyzedand, general rules of landscape lighting effect are achieved.The results make it possible to theoretically predict architectural lighting design effect in the design procedure and help to choose appropriate light spectrum. Based on spectrum theory, landscape lighting effects can be fully quantified.

Abstract:There exists imperfections of the methods for energy conservation verification of the energy efficiency retrofit projects. A new energy conservation verification method was developed by creating energy conversion correction model and four correction coefficients and three calculation formulas were involved, The four correction coefficients were outdoor weather correction coefficient, indoor environmental correction coefficient, internal load correction coefficient and performance period correction coefficient. The three calculation formulas were heating energy conversion calculation, air-conditioning energy conversion calculation and total energy conversion calculation. The energy conversion correction model was adopted to analysis the energy conservation of an office building located in Tianjin to demonstrate the reliability of the correction model and the feasibility of the verification method, and the corrected energy conversion based on consistent conditions before and after retrofit was obtained. 10.23% difference between the corrected energy conversion and the direct energy conversion exists indicating that the correction energy conversion is necessary. The energy conservation difference of 3.03% the calculation result of energy simulation software verified the accuracy of the new verification method.

Abstract:The hourly usage ratio is very important for lighting and equipment energy predicting of office buildings and energy saving calculation of energy efficient retrofit. 17 office buildings in Chongqing were selected to calculate daily usage ratio by using whole-year electrical consumption data of lighting and equipments energy system. According to the different hourly usage ratio, office buildings have been categorized into two main types by using cluster analysis method. Then, the typical hourly usage ratios of two types of office buildings were calculated.

Abstract:The relationship between urban form layout and Urban Heat Island (UHI) intensity response mechanism was quantified and the parameter curves was studied. Large-scale analysis and calculation software such as ArcGIS and MATLAB are used and extract Urban Form and inversed UHI, based on the seven times summer TM images of Tianjin between 1992 and 2013. The results show that: Firstly, the double indicators measure for the UHI intensity was proposed, that is, highest UHI temperature value and total UHI warming. Secondly, the UHI intensity increases with the expansion of urban form area; and in general, gross area of urban form is positively correlated with highest UHI temperature value and total UHI warming.Thirdly, dispersion of the urban form and contagion index are not apparently involved with highest UHI temperature, but correlated with total UHI warming.Fourthly, plague area has a positive relationship with UHI intensity; with a single plague over 50 km 2, highest UHI temperature value will grow rapidly by the linear along with the increase of plague and a quadric curve correlation between plague area and total UHI warming is obtained. Fifthly, there was a negative relationship between perimeter-to-area ratio of the plaque and UHI intensity and a S curve correlation between perimeter-to-area ratio of the plaque and highest UHI temperature value. When the ratio is between 0.005 to 0.04, a quadric curve correlation will be formed between perimeter-to-area ratio and highest UHI temperature value. Finally, urban form fractal dimension is positively relevant with UHI intensity and in a linear relationship with highest UHI temperature and a cubic curve relationship with Total UHI warming.

Abstract:Considering the piles-raft foundation as a composite system of piles and elastic plate, the interaction between piles-raft foundation and soil is translated into the compatible analysis of force and displacement among piles，elastic plate and ground. Based on different models of foundation subjected to centralized load，the settlement coefficient subjected to uniform load is obtained by means of integral, The flexibility coefficient of piles is calculated by considering the pile as elastic member, and with raft identified as four sides free rectangle plate on the ground, the displacement of raft suffering external loads, counter force of soil and generalized displacement on the boundary could be obtained. A semi-analytical and semi-numerical method， using compatible analysis of force and displacement between piles，elastic plate and ground，is developed to analyze the interaction between piles-raft and subsoil. Numerical analysis prove that the semi-analytical and semi-numerical method is provide an accurate and practical calculation tool to. and meet the needs of practical engineering.

Abstract:Traditional nonlinear analysis of RC structures usually adopts nonlinear FEM based on continuum mechanics, and it is hard to reflect macroscopic deformation characteristic, such as local rotation in crack sections and plastic hinge of failure stage. From the perspective of physical model, a new deformation condensation method is developed. The analysis of RC flexural members in the 1-D elastic problem involve three stages based on the concept of deformation condensation. RC flexural members were divided into several elements according to average crack spacing to get numerical model consistent with the physical model with higher computational efficiency tests of RC flexural members reinforced with high strength rebars conducted by Institute of Prestressed Structures in Tongji University, were simulated and the simulation results agreed well with the experimental data indicating that this novel method is applicable.

Abstract:Large particle size gravel strata layer is very difficult for TBM construction which brings about a series of problems for EPB TBM advancing in Beijing Metro. Cutting wheel is an important component of EPB TBM and cutting wheel with reasonable structure is essential for EPB TBM to advance steadily and effectively in large particle size gravel strata. In-situ EPB TBM advancing tests are carried out in large two adjacent shield interval where the strata conditions make it possible to find out the most efficient cutting wheel structure by monitoring key parameters through Real-time Information Management System. Based on the analysis and comparison of advancing efficiency, strata adaptability of key parameters and tools wearing, the following conclusions can be obtained: 1) Spoke cutting wheel has better strata adaptability and higher efficiency than panel cutting wheel as well as more advantages in controlling tools wearing. 2) open ratio ranging from 55% to 65% is the reasonable for cutting wheel. 3) Advancing speed and earth pressure are very important for EPB TBM construction. Compared with panel cutting wheel, spoke cutting wheel can obtained higher advancing speed and more stable earth pressure in tests. However the change of earth pressure should also be paid attention when EPB TBM advancing in fast speed. The advancing speed should be controlled in the range of 20 to 60 mm/min.

Abstract:The mechanical properties of slip soil play a key role in landslide stability. In order to study this control mechanism, multigroup experiments on the slip soil of a landslide were conducted in the Three Gorges reservoir in Zigui county involving consolidated quick direct shear test and consolidated drained direct shear test, through which the strain hardening property of this slip soil has been studiedas well as mechanism of landslide deformation resulting from the strain hardening slip soil. The results show that from plastic deformation to shear failure, the shear stress applied to this slip soil increases all the way. After repeated shearing, its shear strength increases, and the greater the normal stress, the more the shear strength increases, in which process the angle of internal friction contributes the most to its shear strength variation. Through the field investigation and numerical modeling, how the strain hardening slip soil affects the landslide stability was studied. In the process of sliding, the frictional strength of the strain hardening slip soil increases after being shearing, leading to the consumption of the landslide’s kinetic energy, following the phenomenon that a temporary steady state occurs after a short distance sliding.