Abstract:Some recent advances of engineering geological properties of lunar regolith are summarized in the aspect of the influence of specific environment on the lunar regolith properties. Firstly, the geochemical characteristics of the lunar regolith researches are outlined briefly, including mineral characteristics and chemical composition. The influences of lunar regolith size distribution, particle shape and porosity on lunar regolith properties are analyzed. Then, the mechanical properties of the lunar regolith are introduced, including the deformation characteristics and strength characteristics. The main types of lunar regolith simulation are presented, and so do mechanic parameters of the stimulation soil, such as the angle of internal friction and elastic parameters. Lastly the existing problems in the lunar regolith research are pointed out that the effects of environment variables (e.g. the weak gravity) and chemical composition for the engineering geological behavior should be taken into account in simulant test and the dynamic nature of lunar regolith also should be paid more attention.

Abstract:Abstract: Geological characters of dredger fill have been studied in recent years and the engineering geological properties of dredger fill is comprehensively affected by the material composition and microstructure. Because there’re many difficult factors such as sampling and sample preparation, microstructure is indispensable but seldom involved in the former research. Taking the dredger fill in Tianjin Binhai New Area as study object, the mineral composition is identified by X-ray diffraction approach, and the microstructure is studied by scanning electronic microscope (SEM), along with quantificational analysis of the microstructure using WD-5 picture processing system. And then the changing of evaluation indicators in two different reinforcement approaches, such as the size of structure element and pore, abundance, and directional frequency are discussed. The conclusion indicates that after water drainage treatment, the porosity becomes smaller, the dispersed structural elements of soil become agglomerated elements, displaying a variety of oblate. Simultaneously, the pores in the soil are diminished and lose balance, and directing property becomes indistinct. Consolidation degree of soil becomes higher.

Abstract:Sand drains foundation consolidation theory is modified based on the non-Darcy seepage model which considering the initial hydraulic gradient. The control equations are derived and then explicit solutions are obtained. The consolidation behavior of sand drains foundation considering initial hydraulic gradient has been researched. The results show that because of the existence of initial hydraulic gradient, the consolidation degree of stress finally reached a value less than 100%, and the final degree of consolidation decreases with the increase of initial hydraulic gradient. Meanwhile, the initial pore water pressure also influences the consolidation characters, higher initial pore water pressure lead to faster dissipating of pore water pressure and consequently higher degree of consolidation.However, the sensitivity of consolidation degree with initial pore water pressure will reduced as the initial pore water pressure increases to a certain value.

Abstract:A design information-based photogrammetric technique of identifying support positions of braced excavations is presented. Firstly, the acquired image is rectified based on laboratory camera calibration parameters. Then, the position and orientation of the camera in the real world are calculated using the control points method. Support regions designated in the design are projected to the image according to the pinhole camera model. Features of the support regions are extracted from the image and analyzed using a proposed color component relationship to determine whether the support is constructed or not. Finally, all support positions can be determined according to design information and their positions can be identified one by one. This technique can effectively avoid interference caused by complex construction environment. A case study of this technique in a braced excavation project is also presented. The application shows this technique is practicable and effective.

Abstract:Investigations on the residual fracture properties based on Double-K fracture model is implemented. The load-crack mouth opening displacement curves of ten groups specimens with maximum temperature of 600ºC are obtained to calculate the Double-K fracture parameters. Based on the Petersson tension softening curve, the cohesive fracture toughness is calculated both by weight function method and analytical integral method. The two calculating results demonstrate a good coincidence and the validity of Double-K fracture model to post-fire concrete is proved.

Abstract:A symplectic elasticity approach for the analysis of the free vibration problems of rectangular plates with in-plane variable stiffness is presented in this paper. Employing the Hamiltonian variational principle, the problem is formulated within the framework of state space and solved using the method of separation of variables along with the eigenfunction expansion technique based on the assumption that the flexural stiffness of plate varies exponentially with the length coordinate and the Poisson ratio is constant. Unlike the classi¬cal semi-inverse methods where a trial shape function is required to satisfy the geometric boundary conditions, this symplectic approach proceeds without any shape functions and it is a more rational and forward solution method. Exact frequency equations of a Kirchhoff rectangular plate with in-plane variable stiffness are derived. Numerical results are given and the effects of different boundary conditions, the gradient index, Poisson's ratio and aspect ratio on natural frequency are studied through numerical examples.

Abstract:Coupled shear wall structures are often employed as efficient lateral-force-resisting-systems in tall buildings，and the coupling beams are important members of dissipating seismic energy. The desirable energy dissipation mode of conventional reinforced concrete coupling beams is to produce flexural plastic hinge in the coupling beam end under earthquake. However, it is difficult to obtain desirable damage mode duo to smaller span to depth ratio of coupling beam. Moreover, the difficulties of postdamage repair or replacement are larger. Hence, over the past few years, the concept of providing a fuse in a coupling beam has been developed and investigated. The fuse is used to dissipate seismic energy and is easy to be replaced. Because the fuse plays an important role in energy dissipation, the writers develop three kinds of fuse. The seismic behavior of these fuses are investigated through low cyclic reversal tests in terms of the failure mechanism, hysteretic response, strength degradation, stiffness degradation, energy dissipation characteristics, and fatigue properties. Finally, the design recommendations of these fuses are also proposed.

Abstract:A seismic analysis method for cable-stayed bridges with pile foundation based on site-structure integrated model have been developed, incorporating the technique of finite element-infinite element boundary, surface to surface contact algorithm and time-domain explicit analysis. For a 202.5m+300m single tower cable-stayed bridge with group pile foundations, the longitudinal seismic response is analyzed based on the integrated model, focused on the effect of valley site and the characteristics of the ground motion under soil-structure interaction. The results indicate that the shape of the valley and the two-dimensional soil layer will affect short period components of the ground motion, and affect the seismic response of the structure accordingly. For the ground motion, the soil-structure interaction strengthens the components with period close to vibration period of the pile foundation, while has little effect on the components of larger period.

Abstract:The concept of structural damage control is that easily replaceable sacrificial elements deform plastically to dissipate seismic energy while primary components remain elastic or are subjected to minor damage. According that seismic performance of long-span cable-stayed bridges depends mainly on their structural systems, a new damage control strategy, namely reducing the damage of the towers by means of sacrificing the subsidiary piers, was proposed. Three large-scale RC models with rectangular hollow sections were tested under cyclic quasi-static loads to investigate seismic performance of the subsidiary piers. The first specimen is a single-column pier designed originally, while the others are twin-column piers. Shear links (SLs) and buckling restrained braces (BRBs) were installed between the two columns as a series of energy dissipation elements. Failure patterns, hysteretic curves, displacement ductility and energy dissipation capacity, skeleton curves and stiffness degradation of the specimens which were under cyclic loading, and deformation capacity of the energy dissipation elements, were investigated. The results showed that, compared with the single-column pier, the energy dissipation elements increased the stiffness and strength of the twin-column piers and improved their seismic performance.

Abstract:To analyze mechanical performance and failure modes of continuous beams strengthened with BFRP and CFRP, flexural tests were conducted on one comparative continuous beam and seven RC continuous beams strengthened with the two types of fiber. The method of externally bonding fiber sheets on slab along sides of column to avoid column in hogging moment area of beam was applied. The results show that bearing capacity of beams strengthened with BFRP is less than beams strengthened with CFRP, except for ductility，in same condition. Allowable tensile strain of domestic BFRP is suggested as a fixed value of 0.007 for general flexural members, 0.01 for important flexural members. BFRP is a suitable strengthening material for flexural members demanding comparatively low improvement of bearing capacity, better ductility and corrosion resistance in rehabilitation and retrofit projects.

Abstract:A method for structural paramters identification based on HDMR (High Dimentional Model Representation) response surface is proposed to improve the response surface method which applied in bridge structure parameters identification. Using the HDMR response surface method the implicit function relationships between structural parameters and responses are obtained which then applied to identify the structural parameters through a constrained least square optimization strategy. The construction process of HDMR response surface is researched and based on which the implementation program of structural parameters identification is presented in this paper. Numerical examples, which contain a continuous beam structure and a single pylon cable-stayed bridge, are given to investigate the computational accuracy and efficiency of the proposed mehod in structural parameters identification. The analysis results show that, compared to the traditional response surface method, the proposed method possesses a remarkable advantage in computational accuracy. And it is verified that the proposed method is reliable and applicable in the parameters identification of large bridge structures.

Abstract:An innovative joint for timber structures, named prestressed tube bolted joint with slotted-in steel plate, has been designed, to improve the low slip modulus of bolted joints. Different from bolted joints, the innovative joints resist the slip of steel plate by the friction between steel plate and tubes which are inserted into timber holes and prestressed by a pretensioned bolt. Loading tests of single innovative joints and single bolted joints in tension were conduct , which indicates that single innovative joints outshine single bolted joints in load-bearing capacity and slip modulus. If the load is controlled, the ductility of joints is also desirable. Considering the great minimum end distance for dowel-type joint specified by Code for design of timber structures GB5005-2003, anther group of single innovative joints with end distance smaller than that required by the code were tested in tension parallel to timber grain, which indicates that innovative joints with smaller end distance are still great in load-bearing capacity and slip modulus, compared with the performance of single bolted joints; if load is controlled, the ductility of joint is also desirable.

Abstract:This paper defines the elasticity of trip chains as the distribution of the probabilities of different alternatives. Three kinds of travel elasticity are proposed, which are elasticity of mode choice, elasticity of departure time choice, and comprehensive elasticity of mode and departure time. Then methods on how to determine elasticity of trip chains are provided. Based on a dataset of with-in day travel survey in Zhongshan, Guangdong province, two multinomial logit models on mode choice and departure time choice are established to calculate the elasticity of the above three elasticities. Finally comparisons of mode shift prediction considering mode choice elasticity or not under certain travel demand management measures are analyzed. It concludes that mode shift prediction model without considering travel flexibility would exaggerate the effect of TDM, showing that it is necessary to study travel elasticity in transportation management.

Abstract:Based on the new information which was detected through Automatic Vehicle Identification (AVI) technology, this paper proposed a new approach for dynamic OD estimation by using the AVI information. Partial trajectory information, dynamic travel time information and detector measurability were introduced into this approach which refer to the particle filter. First the selection scope and the selection probability were reduced and collected by Bayesian Estimation. Then the absented trajectory of any vehicles was determined by Monte Carlo stochastic simulation and the initial corrected OD matrix was obtained by correcting the individual vehicles trajectory. At last, the initial OD matrix was corrected by the path-link flow function based on the AVI volume information. Finally, the paper analyzed the accuracy of dynamic OD estimation on different coverage of AVI and different accuracy of prior information based on the Shanghai North-South expressway simulation model, the result showed that the accuracy of OD estimation was high when the coverage was more than 60% and relative error of dynamic OD estimation was 28.87% in 50% coverage and 60% accuracy of prior information. It also showed that this approach could be used with low accuracy prior information which can better meet the field need that the current OD information is low precision in China.

Abstract:The combined travel demand model (CTDM) was introduced and a combined destination-mode choice model was established. The model parameters were estimated by applying stepwise maximum likelihood estimation method. According to joint use requirement of stated preference (SP) data and revealed preference (RP) data, the SP-off-RP survey method was improved. A web-based survey software named "web-based survey design and data collection platform of individual behavior " was developed to collect data, which was used to calibrate the parameters of the combined destination-mode choice model. Taking film-watching behavior of students in Jiading campus of Tongji University as example, the parameters of model were calibrated with SP/RP data. The results show that parameters calibrated by SP/RP data have better accuracy.

Abstract:This study proposed a regional safety prediction model based on the data from Hillsborough County, Florida, USA. By regionalizing the county into 200, 500 and 700 traffic safety analysis zones, we developed a Bayesian spatial model with consideration of spatial autocorrelation to relate crash rate to zonal factors including road network, trip generation etc. By the model results, we investigated the relationships between traffic safety and zone-level factors, as well as the effects of varied zoning schemes on the estimation of factor effects. Results show that compared with the traditional Poisson model and Poisson-lognormal model, the Bayesian spatial model has a better model-fitting; the greater the total zone number, the higher the spatial effects; the factor estimates are robust given a specific zoning scheme; the most significant factor affecting zonal safety is the total road length with speed limit over 35 mph. The present research contributes to the regional safety modeling in context of traffic safety planning.

Abstract:As one important method of freight demand analysis, behavioral models allows researchers to describe the characteristics of shipper’s freight service choice behavior and forecast the market demand of different freight service, so they are widely applied to evaluate the expected effect of freight transportation infrastructures and policy actions. After reviewing 46 documents since 2000, this paper sorts out them based on the research theme of disaggregate behavioral freight model and analyzes their theory basis, modeling process and data sources. Then it elaborates the methods and results of these literatures from the perspective of identifying the factors influencing shipper’s choice behavior, forecasting the potential market share and estimating the quality attributes value of freight service. Finally, it discusses the shortcomings of exist literatures and puts forward some issues to be further studied.

Abstract:Two typical highway traffic data measured by WIM equipment in China and France are compared, some statistics and analysis works have been conducted. Traffic flow and load properties are compared in a detail way. The results show that: axle weight, gross vehicle weight and traffic volume of France’s are smaller than that of China’s which indicate an obvious increase comparing with the vehicle data that are used for The current bridge criterion (JTG D60-2004). The constitution of daily traffic show a timely change: trucks have a higher proportion during the low tide, but a lower proportion in peak time.Results can be conclude from those data, that a basic hypothesis of vehicle load model for China design code, which is all vehicle lanes are uncorrelated to each other, may not valid. Both China and France data show traffic flow and load properties in different lanes have obvious differences. Base on those research results, it is recommended at the final that site-specific vehicle model is very necessary for some design and assessment work, and also to improve current design load model, different lanes should be considered to have different model, and a loading length depended load-model should be adapt for diversity span bridge regarding the actual extrapolated effect far outweigh code value.

Abstract:Cement and emulsified asphalt within the cement asphalt emulsion mixture would experienced interactions，which created more complex air void microstructure compared with normal hot mix asphalt. The influence on air void distribution and air void features from emulsion and cement content were studied by computed tomography, air void structure of micro-scale were further researched by scanning electron microscope. The results of the study showed that the air void size, total air void area and average single air void area of cement asphalt emulsion mixture specimens section was decreased with the increase of emulsion content; CT visible air void of mixtures and the ratio of big air void was increased observably when the cement content was more than 3%. Internal air void structure of cement asphalt emulsion mixtures maybe looser than traditional hot mix asphalt for the interaction of cement and emulsion asphalt.

Abstract:The total concentrations and different forms of heavy metals were investigated and analyzed to evaluate pollution characteristics and potential release risk of heavy metals in sediment cores in an urban river of Chaohu City, Anhui province by using a modified BCR sequential extraction procedure. The result showed that the total concentrations of heavy metals ranged from 29.5 to 224.3 mg•kg-1 for Pb, from 21.3 to 78.1 mg•kg-1 for Ni, 67.5-126.3 mg•kg-1 for Cr, 50.7-217.4 mg•kg-1 for Cu, respectively. Sediments from the East Ring River (ERR) located in the old town showed significantly higher total concentrations of Pb, Ni, Cr, Cu than those from the West Ring River (WRR) in the new town. Especially, the differences in total Cr concentration between sampling sites were more significant, as compared to the other heavy metals. There were significant differences in vertical distributions of total concentrations of heavy metals in sediments cores from four sampling sites. In general, the two sediment cores from the WRR had significantly lower heavy metals and smaller variations with depths than those from the ERR. Due to historical heavy pollution, the ERR showed high concentrations of heavy metals not only in subsurface but also in deeper layers of the sediment cores and fluctuated dramatically with depths. The vertical distribution characteristics of heavy metals could well indicate the surrounding environment situation and heavy metal pollution dynamics. The ratios of exchangeable and carbonate-bound fractions in the total heavy metals were not more than 5%. Pb and Ni existed mainly in reducible and residual fractions, respectively. Cr existed mainly in oxidizable and residual fractions, and Cu existed mainly in reducible and residual fractions. Potential ecological risk assessment based on the ratio o f secondary phase to primary phase (RSP) for the four sediment cores showed that sediment cores from the ERR had significantly highest RSP than those from WRR. Especially, the sediments from the ERR was moderately or heavily polluted with Pb and Cr based on the RSP analysis and had a potential and high ecological risk.

Abstract:According to the base test requirements of ‘International Convention for the Control and Management of Ships in Ballast Water and Sediments’, the collimated light beam was employed to irradiate eight species of microalgae, and to investigate on the inactivation efficiencies of UV-C on them in a dark cutivation environment. The results showed that UV-C had some inactivation efficiencies on Cyclotella meneghiniana Kutz, Nitzschia palea., Chlamydomonas microsphaera and Microcystis sp., the inactivation rate increased with the increasing of UV-C doses. Low dose of UV-C could stimulate the growth of Ankistrodesmus falcatus and Scenedesmus obliquus. When the dose was improved to more than 300 mJ/cm2, algal cell numbers started to decrease. UV dosage less than 400 mJ/cm2 presented low inactivation efficiencies on Fragilaria capucina and Cryptomonas ovata Her. Therefore, the inactivation efficiencies by UV-C on microalga were relatively low. In addition, the algal cell size was found not one of the factors influencing on the UV-C inactivation efficiencies. The algal species, the existence and inexistence of the algal cell wall, and the difference components of algal wall might be the main factors influencing on the different inactivation efficiencies.

Abstract:Based on nonparametric identification technique and finite element method, a nonlinear dynamic parameter identification method for spindle-holder interface is presented, in which the double contact parts between spindle and holder is considered as a nonlinear element descripting by system state variables. A finite element model of spindle holder system is constructed by HyperMesh，and its nonlinear transient response analysis is conducted using Radioss solver. With Newton's second law of motion，the time history data of nonlinear contact force of the interface then be deduced. Least square estimates with the Chebyshev polynomial basis is employed to approximate the sample data, and an analytic model of the nonlinear contact force of the interface is obtained.

Abstract:Based on the PEMS on-board emission testing method, burning with the pure national Ⅳ diesel, 10% and 20% by volume butanol-diesel blends on a diesel PCV, the experiment equipped with an on-board gas emission testing system which made in Horiba of Japan. Comparing with the three different kinds of fuels’ emission in different kinds of roads type, referring to the different emission in different working conditions, the characteristic of the on-road gas emission from a diesel PCV with butanol-diesel blends have been analyzed. The result shows that, a diesel PCV burning with the butanol-diesel blends can reduce the CO emission obviously, especially on the medium-high-velocity working condition; the THC emission increases with the increasing of the butanol concentration; the CO2 emission basically unchanged,; the NOX emission changed a little because of the influence with the working condition and the engine parameters.

Abstract:The regularized methods are widely used in geophysical inversion to improve the ill-posedness of inverse problem. The selection of the regularization parameter is very important to the results of regularized inversion, most of the recent researches usually concern about a single way such as a fixed value of regularization parameter. The research on how to choose the optimal regularization parameter is uncertain. In this paper, by establishing layered magnetotelluric (MT) models, the conjugate gradient method is used in Occam’s inversion, we compare the inversion results of many ways to select the optimal regularization parameter with different initial model in order to analysis the characteristic and some conditions of each methods. The results show that the adaptive regularization algorithm can get a similar inversion result compared with some traditional ways such as L-curve method, and it’s faster and easier to use. Moreover, with the purpose to reduce the limit of inversion depending on the initial model and improve the stability of inversion, we put forward an improved adaptive regularization method which selects a large ratio of the misfit functional and stabilizing functional as the initial value of regularization parameter, takes an automatic decay coefficient scheme to reduce the regularization parameter when misfit functional decline slowly. Model test shows that the method is much lower depended on initial model than other adaptive algorithms, the inversion result is stable and it can be further improved the efficiency of regularization inversion.

Abstract:AAnalyses of the seismic data from the Baiyun Sag in the Pearl River Mouth Basin of Northern South China Sea indicate that fault systems mainly developed since the Eocene, showing tensional or transtensional features during various time intervals. Three fault groups are dominated: NWW, nearly EW and NE. Based on their lateral distribution and form, the faults could be divided into three combinations of parallel, echelon and dendritic types. These faults had played a critical role in the tectonic evolution and deposition process in the Baiyun Sag, and four stages of faulting activities can be identified: strongly active period (Tg-T8), reduced active period (T8-T6), stable period (T6-T2), and re-active period (T2-T1).

Abstract:The perishable products’ dynamic pricing with quantity discount was studied. Assuming that consumer’s reservation price draws from a uniform distribution. The seller used two-phase pricing, and introduced the all-quantity discount policy when the remaining inventory was bigger than zero in second phase. When the quantity discount was not considered, the basic model was given to present the optimal two-phase pricing strategy. Based on the basic model, the extension model gave the optimal quantity discount strategy. Finally, MATLAB was used to implement a numerical simulation and sensitive tests were provided based on the second phrase’s price discount is the linear function of the consumer’s proportion that purchased two units product. We conclude that the remaining inventory lowers and the seller’s profit increases obviously. The profit increment rate increases significantly when consumers’ reservation prices vary significantly.