Abstract:According to the geometry characteristics of tapered pile cap, differential deformation of pile-soil and soil arching effect in embankment, the pile-soil stress ratio calculation formula for the composite foundation with tapered pile cap was deduced, taking into account the behavior of pile top piercing the embankment and pile end punching the soft substratum. Numerical model was established by using finite difference software（FLAC3D）. The numerical results of the pile-soil stress ratio decrease from 3.06 to 2.08 as the taper angle increases from 5.7° to 14°, and the calculated results decrease from 3.13 to 2.19 accordingly. The relative error falls within the range of 2.01%~6.44%，which indicates that the calculated value of pile-soil stress ratio is consistent with the simulation value. Furthermore，the effects of equal section piles，conventional pile with cap and taper-capped pile on the settlement of embankment were compared. With the same size of the top section of the pile，the composite foundation with tapered pile cap exhibits a smaller settlement value.

Abstract:To discuss the dynamic response of buried harmonic torsional load in vertically non-homogeneous saturated soil，the soil shear modulus was assumed as a nonlinear distribution with the depth defined as an exponential function，and the dynamic differential equations of half space were established by using the Biot's consolidation theory and elastic-dynamic theory. The expressions of stress and tangential displacement in the Hankel transform domain were then acquired by solving the dynamic differential equations using the method of Hankel transform，and the true stress and tangential displacement can be obtained by Hankel inverse transformation as well. The corresponding calculation program by Mathematica was compiled based on the obtained solutions. A detailed parameter analysis completed by the program indicates that，the stress and tangential displacement of the soil show obvious fluctuations with the change of radius，and the frequency of fluctuant curves increases with the loading frequency. In addition，the maximum tangential displacement of soil occurs and there is a sharp change of stress on the loading surface. The influence range of the buried harmonic torsional load is about two times the action radius to the loading surface. Furthermore，the largest tangential displacement of the soil is negatively correlated with the depth of buried load，and it is reduced by 90% when the depth of buried load is 2 times the action radius. When the depth of buried load is greater than 4 times the action radius，the largest tangential displacement is approximately equal to zero.

Abstract:The formation mechanism of soil arching effect behind the retaining wall was significantly analyzed in the case of limited backfill width. It is assumed that the small principal stress arch is circular arc. Considering the limit equilibrium condition of the friction point between the retaining wall and the soil，the expression of the deflection angle of the large and small principal stress was derived. On this basis，considering the translational displacement mode of rigid retaining wall and the horizontal differential element method，the theoretical expressions of active earth pressure resultant force and intensity distribution of finite width soil behind the wall were established. Comparison with laboratory test data and previous methods indicates that the earth pressure value obtained by this method has preferably rationality. Finally，the distribution of the active earth pressure was analyzed under different ratios n of the width to height of the backfill. The results show that the active earth pressure increases with the increasing n，but approaches to a constant value as n reaches a threshold of limited width of 0.5.

Abstract:The stability of slopes under intermittent heavy rainfall is studied. The soil above the wetting front is subjected to dry-wet cycles under intermittent heavy rainfall. Considering the influence of dry-wet cycles on the soil permeability and soil-water characteristics of slope，the traditional Green-Ampt infiltration (GA) model is improved. The expression of slope stability coefficient under intermittent heavy rainfall is established considering the deterioration of dry-wet cycles on soil strength. For slopes without considering intermittent heavy rainfall，the improved GA model can be simplified to the traditional GA model，which indicates that the traditional GA model is a special case of the improved GA model. The results obtained by using the improved GA model and the stability evaluation method are basically consistent with the actual engineering situation，which proves the reliability of the method. According to the variation characteristics of rainfall infiltration rate，the rainfall process can be divided into three stages: stable stage，continuous reduction stage and mutation stage. The slope infiltration depth and instability time of traditional GA are obviously behind that of the improved GA model. Compared with the improved GA model，the traditional GA model which only improves the stability evaluation method is consistent in the instability depth and delayed in the instability time.

Abstract:Based on the research of prediction methods for foundation or subgrade settlement by existing combination model，firstly，an analytical model of freshness function is proposed to measure the newness-oldness degree of measured settlement data，considering the features of newness-oldness degree and its influence boundedness of measured settlement data. The proposed method can also reflect the effect of time distance between the measured and predicted point，measured error and boundedness of newness-oldness as well as its influence degree of the measured data on the settlement prediction. Secondly，based on statistical theory，a disposal method of measured data sample is developed which can exclude the unreasonable settlement prediction caused by some abnormal measured data. Then，using the above-mentioned model and method，a new method for combined prediction of foundation or subgrade settlement is put forward，which can reflect the influence of abnormality of measured settlement data，their oldness and newness degree and boundedness of its influence degree on settlement prediction of foundation or subgrade. Finally，it shows the rationality and superiority of the proposed model and method by calculation of actual engineering examples and comparison and analysis among the prediction results by the proposed and the existing similar methods as well as the measured results.

Abstract:To investigate the settlement control measurement on the retaining wall embankment under the dual slurry shield tunnels underneath traversing construction，taking the retaining wall embankment in Beijing Capital Airport Express Line at Wangjing on Beijing-Shenyang passenger high-speed railway line as engineering background， in-situ settlement monitoring data and shield construction parameters were analyzed. Settlement regulations of the embankment were narrated. Experiences on real-time adjustment of shield construction parameters，comprehensive use of pre-grouting，supplementary grouting and secondary grouting were summarized. The measurement results show that the relationship among tunneling parameters，as well as slurry parameters，is close. A relatively high thrust force，slurry pressure，slurry unit weight and slurry viscosity are the key parameters that ensure the shield to traverse quickly and safely with small disturbance to the embankment. Synchronous grouting at a pressure is 0.15~0.2 MPa greater than the slurry pressure and with a volume about 2.5 times the theoretical value can fully fill the shield tail void. Ground pre-grouting effectively improves the soil and moderately raises the embankment. Ground supplementary grouting at a pressure of 1.2 MPa can timely restrain and even compensate the settlement of the embankment. Secondary grouting in tunnels at a pressure of 1.2 MPa and a speed of 100 L/min reduces the post-construction settlement of the embankment.

Abstract:To truely reflect the variation law of settlement characteristics of Super High Rise-Steel Reinforced Concrete (SHR-SRC) structure with the upper load during the construction process in the ultra-thick collapsible loess area and guide the safe construction，a complete set of monitoring system was established to dynamically track testing settlement and deformation of SHR structure in the whole construction period (2.5 a) by the original data in the test area. The settlement characteristics of a SRC structure were analyzed systematically by actual monitoring results and ABAQUS finite element analysis. The results showed that the overall settlement of the SHR-SRC structure was relatively uniform，and the maximum settlement rate was 0.28 mm / d in the construction process. The positive and negative strain values of the underground test pile near the core tube were small，but far away the core they went by contrary. Under the condition of gentle construction intensity，local "rebound" phenomenon occurred briefly. The simulation showed that the largest displacement occurred at the top of the center pile at the bottom of raft，followed by the side pile，and the smallest displacement occurred at the angle pile. The settlement difference of the same pile indicated that the pile itself had axial compression. However，due to the complex mechanism of the loess and the structure，the related law is still needed to be further investigated and discussed.

Abstract:An unrestrained timber beam and a dovetail joint timber beam are placed in Lasa，and non-load test and step loading test are carried out，respectively，to study the strain parallel to grain of the timber beam under environmental temperature effect. According to the test data，the elasticity modulus parallel to grain of the wood，the tension and compression stiffness and rotation stiffness of the dovetail joints are identified. Considering the environmental temperature effect，the parameters are determined as variables related to the temperature variations. According to the construction features of the dovetail joint，the tension and compression stiffness in the temperature increasing stage and temperature decreasing stage are different. The influences of upper load and boundary conditions on the strain parallel to grain are analyzed. The results show that the strain variations of unrestrained beam under environmental temperature effect is unconcerned with the top load，and the strain variations of restrained beam increase along with the environmental temperature. The extra strain is induced by the second order moment of the counterforce at the beam end，which increases along with the temperature and the upper load. Finally，according to the theoretical formula of extra strain，the measured value and calculated value matched well，which indicates that the theoretical formula of the extra strain is rational.

Abstract:In order to study the thickness evaluation of zero-strength layer in the calculation of fire resistance for Cross-Laminated Timber (CLT) floor，the ultimate load-carrying capacity test and fire test of the CLT floors with three and five layers were carried out，respectively. Based on the domestic and foreign wood structure design codes，combined with the simplified design method that ignores the elastic modulus of laminated laminates and only considers the thickness contribution to the moment of inertia of composite sections as well as the reduced cross-section method，a suitable method for the CLT floor was obtained. The variation law of zero-strength layer thickness of CLT floor with charring depth was analyzed. The flexural capacity of CLT floor under high temperature based on the thickness of zero-strength layer in this paper and the results based on EN1995-1-2 were compared. The results showed that the values by the calculation method agreed well with the experimental values. When the charred layer of the CLT floor reached the glue line between cross and longitudinal-layer，the thickness of the zero-strength layer changed continuously；and when the charring depth reached the glue line between longitudinal and cross-layers，the thickness of the zero-strength layer changed sharply. The bending capacity of CLT floor under high temperature obtained by the calculation method in this paper was more reasonable than the prediction of EN1995-1-2，which had better reference value for the fire resistance design of CLT floor in practice.

Abstract:To investigate the fire development，smoke movement，and temperature development within the whole building and steel members，a 1 ∶ 4 scaled portal frame building was designed and built for a medium fire test. The temperatures of the hot gas and steel members were measured in the test. The formulation recommended by《Code for fire safety of steel structure in buildings》(GB51249-2017) was used to predict the temperature-time curves of steel members. The test results indicate that the maximum temperature of hot smoke decreases from the fire origin to the surrounding zone and distributes symmetrically on either side of the roof ridge. In the case of localized fire，the space in the building can be divided into high temperature zone of hot smoke layer，sub-high temperature zone and zone below the hot smoke layer. The temperature distributions within the steel sections are approximately uniform. The temperature variation of steel members lags behind that of the surrounding hot gas during the growth and decline stage. Meanwhile，the effect of flame radiation on the temperature elevation of steel members under the hot smoke zone needs to be considered in addition.

Abstract:In order to accurately understand the applicability of Bridge Weigh-In-Motion (BWIM) technologies in different types of bridges，and therefore to provide a theoretical basis for the selection of BWIM technology，the accuracy and stability of BWIM systems were studied by adopting the most widely used short- to medium-span concrete girder bridges in China. Firstly，beam bridge models with typical cross sections and span lengths were established based on the standard highway bridge drawings，and the dynamic responses of vehicles and bridges under different loading conditions were obtained by means of numerical simulation. Then，the gross vehicle weight and axle weight were calculated by classical BWIM methods and the identification errors were obtained. Finally，the influence of some important factors such as bridge span length，section type，vehicle type，vehicle speed，sensor installation position，road roughness and measurement noise on the identification accuracy was studied based on parametric studies. The research results show that，for gross weight identification，satisfactory accuracy can be achieved by the BWIM technologies investigated under various complex working conditions with different types of bridges and different bridge span lengths and cross sections；for axle weight identification，better identification accuracy is achieved on shorter bridge span lengths and the best accuracy is achieved on hollow slab bridges，followed by T-beam bridges and small box girder bridges. In addition，the deterioration of road roughness and input signal noise may adversely affect the axle weight identification accuracy of the BWIM systems. Therefore，it is of significant importance to maintain the road surface condition and control the input noise in order to obtain the reliable weighing results.

Abstract:Single Shot Multibox detector based video surveillance system for active anti-collision between vessel and bridge is proposed aiming at the limitations of the existing systems in accuracy，robustness and efficiency. A vessel-exclusive dataset with tons of image samples is established for neural network training，and an SSD (Single Shot MultiBox Detector) based object detection model with both universality and pertinence is generated with tactics of sample filtering，data augmentation and large-scale optimization，which can realize the stable and intelligent vessel detection. Comparison results with conventional methods indicate that the proposed navigational object detection method shows remarkable advantage in robustness，accuracy，efficiency and intelligence. In-situ test is carried out at Songpu Bridge in Shanghai，and the results illustrate that the method is qualified for long-term monitoring and provides information support for further analysis and decision making.

Abstract:The classical system reliability theory only involves random static load with constant value，which cannot provide reasonable estimation for the structure under random static load with variable value，and underestimates the risk of the structure. In view of this，a global reliability evaluation method for framed structures under static load with variable value is proposed，which is based on the shakedown theory with the shakedown state defined as the limit state. Firstly，a single performance function is proposed，and two implementations for calculating the performance function are introduced；Secondly，based on the probability density evolution method (PDEM)，a generalized density evolution equation of the performance function is derived，and its approximate solution is obtained by introducing Dirac δ sequence algorithm，and then the global reliability of the structure can be obtained by the one-dimensional integral of the probability density of performance function. Finally，several examples are investigated to verify the proposed method. The results show that: 1) the proposed method is of high accuracy and efficiency；2) The global reliability obtained by the proposed method can evaluate the safety of the structure under static load with variable value more rationally.

Abstract:Overhead transmission lines are lifeline projects，and ice load is one of the greatest threat to transmission lines safety. On the basis of the project of Chinese Grid Xinjiang Electric Power Research Institute，the finite element numerical simulation models of overhead transmission lines were established by means of ANSYS software. Using the technique of birth and death of the element for ices，the finite element analyses of zippered and simultaneous ice-shedding vibrations were carried out. By analyzing the modeling parameters of the overhead transmission lines，the influence of altitude difference on the vibration response of single-span ice overhead transmission lines was studied，and compared with the results of the experiment of the scaled model. The results show that the simulations of the zippered and simultaneous ice-shedding are well matched with the experimental results and the discrepancies are less than 5%，which proves the accuracy of the simulation method. If the altitude of two suspension points is the same，the maximum jumping height first increases with the deicing speed and then is maintained at a constant value，while the maximum force is not affected by the deicing speed. If the altitude of the two suspension points is different，the maximum jumping height increases exponentially with the increase of altitude，and the jumping height of the zippered ice-shedding gradually approaches the value of simultaneous ice-shedding when the initial stress is constant. The existence of altitude aggravates the upturn of lines，and the maximum jumping height is greater than the sag of iced line. Meanwhile，the occurrence of upturn can be reduced by decreasing the initial stress and icing thickness of transmission lines.

Abstract:Pullout tests were conducted to investigate the influences of different embedded depths，temperatures and textile modification on the interfacial bonding properties between alkali-resistant（AR） glass textile and cementitious matrix by using a MTS load frame. The experimental data indicated that the bond properties between the glass textile and cement matrix were related to the embedded depth，textile modification and temperature. At the room temperature（25 ℃），the pullout stiffness，ultimate pullout force and pullout work increased，and the equivalent bond strength decreased with the increase of the embedded depth（15~25 mm）. When the embedded depths were constant （15 mm），the pullout stiffness and ultimate pullout force of bundles decreased with the increase of the temperature. Impregnating epoxy resin and sticking sand on the surface of AR-glass textile can increase the ultimate pullout force，and sticking sand on the glass textile can increase the ultimate pullout force when the temperature varied from 25 ℃ to 300 ℃. However，impregnating epoxy resin and sticking sand on AR-glass textile do not significantly influence on the ultimate pullout force at the temperatures between 400 ℃ and 500 ℃，and can slightly reduce the ultimate pullout force.

Abstract:The volcanic cinder has the characteristics of irregular shape and sharper angles，and its shape characteristics affect the material engineering properties. In order to explore the shape of volcanic cinder particles，the image and shape index of volcanic cinder were obtained by AIMS aggregate image measurement system. The fractal dimension and normal distribution method were used to discuss the influence of fractal dimension and shape as the particle size change on the particle shape and fractural dimension. The differences in shape between the volcanic cinder and general rock mass were also investigated. The results show that as the particle size decreases，the elongation and texture decrease，the angularity，sphericity and fractal dimension increase，the volcanic cinder approaches spherical and massive，and the surface angularity is reduced. All the shape indicators have a good correlation，and the angularity is the most sensitive to the change of the particle size. Thus，it can be preferentially selected to describe the shape of the volcanic cinder. In addition，comparison with pebbles and crushed stone shows that the change of volcanic cinder elongation and texture is not as significant as that of the pebbles and crushed stone under different particle size. Moreover，the texture and angularity of volcanic cinder are larger than those of pebbles and crushed stone，indicating that the volcanic cinder has more angular edges and a rougher surface.

Abstract:This paper studies the thermal responses of human subjects with different local cooling methods (radiation，conduction and convection) in hot-humid environments. Through experiments in the hot-humid environments in the experimental room，the data of subjective feelings were collected and the different effects generated by different local cooling methods on the local and overall thermal comfort were then analyzed. The obtained results showed that the time before subjects reached static-state condition differed with different local cooling: the time was less than 5 minutes with local convective cooling; the time was 10 minutes with conductive cooling and 20 minutes with local radiant cooling. In the reference condition，necks，legs and backs exerted large effects on overall subjective responses. When local cooling was applied，the local body parts which exerted large effects were those which were locally cooled directly，like upper-arms (local radiation)，lower-arms (local conduction) and heads (local convection). Moreover，according to the regression results of the thermal comfort vote at 26/28/30 ℃，it is the best to choose local radiant cooling when the ambient temperature is lower than 27.55 ℃，local convective cooling with the ambient temperature at 27.55-28.96 ℃，and local conductive cooling with the ambient temperature higher than 28.96 ℃，respectively.