Table of Content

25 April 2023, Volume 51 Issue 4

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2023, 51(4):  0. 

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Architecture & Civil Engineering

Wind Tunnel Test Research on the Effect of Rough Strips on Wind Loads of A Super High-Rise Building



YANG Yi, WANG Xin, JI Changhui

2023, 51(4):  1-8.  doi:10.12141/j.issn.1000-565X.220290

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Rough strips such as curtain wall skeletons affiliated with the outer curtain wall envelopes of super high-rise buildings will change the flow pattern around the building, thereby affecting the wind loading characteristics of the buildings. However, the current Chinese building structural load code lacks relevant regulations in this regard. Given this, a systematic comparative study on a typical super high-rise building was performed under the two conditions of with and without the rough strips on the building surface by means of the HFPI (High Frequency Pressure Integration) test. By analyzing the changes of the wind loading characteristics such as wind pressure coefficient, base overturning moment and structural shape factor of wind load, the effect of rough strips on the wind load of the super high-rise building structure was studied. The results show that: setting of rough strips has little effect on the positive pressure on the building surface, but it will significantly reduce the absolute value of the peak negative pressure, with a maximum decline of about 39.8%; it will significantly affect the wind pressure distribution in the building corner area and lateral sides, leading to the significant reduction of the mean wind pressure coefficient and fluctuating wind pressure coefficient in the lateral sides, and the maximum decline is 24% and 30%, respectively. Overall, setting rough strips is beneficial to the wind-resist design of the building claddings. Setting of rough strips will affect the overall wind load of the structure. At a positive blowing angle of 0°, the rough strips will slightly increase the structural shape factor of the wind load in sections along the height of the building, with a maximum increase of about 8%, and the base overturning shear force and base overturning bending moment of the X-axis will slightly increase by 4.9% and 6.0%, respectively. Setting the rough strips has an impact on the wind angle of the peak acceleration at the top of the building, and can reduce the peak acceleration by about 7.91%.

Seismic Performance of Hoop Head Tenon Frame Structure Reinforced by Sparrow Brace Type Damper



CHEN Qingjun, LI Bingzhou, CHEN Yinian, et al

2023, 51(4):  9-20.  doi:10.12141/j.issn.1000-565X.220160

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In order to study the seismic performance and reinforcement method of the wooden structure of Guangfu ancient building, two typical hoop tenon frames of Guangfu wooden ancestral halls with different structural forms were designed and manufactured by using merbau wood. A sparrow brace type damper for strengthening the tenon and mortise joints of the wooden structure was proposed and manufactured. Cyclic loading tests were carried out on the wooden frames before and after strengthening using the sparrow damper and the seismic performance of the structure and the reinforcement effect of dampers were studied. The results show that the damper can repair the damage caused by the cyclic loads, and provide higher initial stiffness in small rotation angle for the damaged mortise joint. It cooperates with the mortise joints well, so as to improve the joint stiffness, ultimate bearing capacity and energy consumption capacity, so that the ultimate bearing capacity of the reinforced specimens is higher than that of the unreinforced specimens. The unreinforced specimen show the phenomena of mortise and tenon separation and local compression buckling of mortise and tenon joints after loading, while the failure modes of the reinforced specimen are mainly mortise and tenon separation, local compression buckling of mortise and tenon joints, and vertical splitting cracks along the grain. The hysteresis curves of each joint show obvious "pinching" phenomenon. The strength degradation coefficients of all tenon joints are greater than 0.83, which shows stable bearing capacity under cyclic load. The ring stiffness and the equivalent viscous damping coefficient of each joint gradually decrease and tend to be stable with the increase of rotation angle. Equivalent viscous damping coefficients of the side-span frame specimen joints gradually stabilize from 0.1 to 0.2, while those of the mid-span frame specimen joints gradually stabilize from 0.05 to 0.1. With the reinforcement of damper, the total energy consumption of the mid-span frame specimen and the side-span frame specimen increases by 67% and 19%, respectively.

Study on the Improvement Effect of Rocking Wall Internal Force in Multiple Rocking Sections System and Analysis of Influencing Parameters



WANG Suguo, ZHONG Xupan

2023, 51(4):  21-30.  doi:10.12141/j.issn.1000-565X.220481

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Using multiple rocking sections system can effectively reduce the internal force demand of the rocking wall itself while ensuring the improvement of structural deformation and seismic performance. This form also has the advantages of being easier to manufacture, transport, and install. In order to analyze the improvement effect of multiple rocking sections system on the internal force of the rocking wall, the paper derived a simplified calculation formula for the displacement of frame structure in multiple pinned rocking wall system and internal force of multiple pinned rocking wall by combining the characteristics of segmented rocking walls and different boundary conditions from rocking at base only system. And it further analyzed the influence of the rocking wall stiffness ratio and the number of rocking sections on the internal force of the rocking wall, which was compared with the corresponding situation of rocking at base only system. The research shows that the peak value and variation range of internal forces can be significantly reduced when setting multiple rocking sections over the height of rocking system in comparison to full slice rocking system. Under uniform distributed load, the distribution regularities of bending moment and shear force of each section of rocking wall in multiple rocking sections system is similar. Furthermore, the peak bending moment of the rocking wall in rocking at base only system is m² times that of the rocking wall section in multiple rocking sections system, and the peak shear force of the rocking wall in rocking at base only system is m times that of the rocking wall section in multiple rocking sections system. However, when subjected to inverted triangle load, the bending moment and shear force of the upper rocking wall section are larger than those of the lower rocking wall section in multiple rocking sections system. The influence of stiffness ratio on rocking wall internal forces is obvious when the ratio varies in an appropriate scope of 1.0~5.0. When the stiffness ratio increases in this scope, the influence extent increases first and then decreases. When the stiffness ratio is not in this scope, whether too large or too small, the internal force of rocking wall is not sensitive to this parameter. At this point, the improvement effect of the rocking wall internal force by the stiffness ratio is not significant. The decreasing amplitude of rocking wall internal force decreases with the increase of the number of rocking sections, so when using multiple rocking sections system, the number of rocking sections should not be too large. In addition, the analysis also shows that the influence of the stiffness ratio and the number of rocking sections on the internal force of the rocking wall is relatively independent, and the influence effects are not coupled.

Dynamic Characteristics of RC Rigid Frame Arch Bridge Strengthened by Plate-Truss Combination



XIE Xiaoli, GOU Wenxin, PANG Mulin, et al

2023, 51(4):  31-43.  doi:10.12141/j.issn.1000-565X.220152

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The common strengthening methods of reinforced concrete (RC) rigid frame arch bridges mostly belong to local strengthening rather than overall reconstruction. Therefore, the improvement of structural mechanical properties is extremely limited, making it difficult to meet the increasing demands of highway traffic loads in China’s current stage. In view of the above problems, this paper firstly proposed a new strengthening method, the Method of Plate-truss Combination Strengthening. This strengthening method involves erecting steel trusses on both sides of the main beam, and uses measures such as planting rebars, welding, laying steel mesh, and pouring concrete to firmly connect the steel trusses with the main beam, forming a composite structure of a plate and truss. This transforms the structural load-bearing system from the main beam to the plate-truss composite system, achieving optimization of the structural load-bearing. Then, the above method was used to reinforce a rigid frame arch bridge. Through finite element simulation and bridge dynamic load test, the effectiveness and practicability of the new strengthening method were verified. The results show that after strengthening, the natural frequency of the structure is effectively improved, and the vertical stiffness, the bearing capacity is significantly increased. The theoretical value of vertical bending frequency in the first-order of the structure is increased by 80.5% compared to before reinforcement, and the deflection value of the structure under Highway Class-I load is reduced by 56.8% after reinforcement compared to before. The stress level of the concrete components is reduced by 10.9% to 69.8% compared to before reinforcement. The strengthening method can improve the dynamic characteristics of the structure. The vertical vibration effect of the structure after reinforcement is less than that before reinforcement. The measured impact coefficient is much smaller than the current normative value, and the dynamic performance of the structure is good.

Research on Numerical Simulation of Rail Non-contact Nondestructive Testing Technology



DAI Gonglian, CHEN Kun, GE Hao, et al

2023, 51(4):  44-52.  doi:10.12141/j.issn.1000-565X.220018

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Focusing on the shortage of existing rail inspection technology, the paper proposed a non-contact nondestructive inspection method based on air coupled guided wave. An acoustic-solid coupling simulation model was established to simulate the whole process of air coupled guided wave excitation and reception, and verified based on acoustic theory. Firstly, the influence of different damage severity of rail bottom on the received guided wave signal was simulated and analyzed through the numerical model. Then, a damage assessment method based on wavelet coefficients of the center frequency of the excitation signal was proposed, considering the influence of high intensity random white noise on air coupled guided waves. The results show that, based on the Snell's law and acoustic theory, the optimal excitation angle and reception angle of rail air-coupled guided wave detection is 6.6°; the air coupled guided wave still has the advantage of waveform stabilization, energy concentration and high interference resistance; regardless of the size and the spatial location of the damage, the arrival time of the wave packet center of the received sound pressure time domain signal is almost the same. The range of damage index will be different with the change of damage severity. The wavelet coefficient method based on the center frequency of the excitation signal is simple, feasible, and accurate, and it is suitable for the damage detection of known narrowband guided wave signals, and it can effectively identify rail damage when the received signal is seriously polluted by noise. It is feasible to detect steel rail damage based on air-coupled guided wave.

Influence of Electroosmosis-Calcium Chloride Treatment on the Deformation of Sodium Sulfate Saline Soil



ZHANG Heng, HUANG Junguang, LI Weike, et al

2023, 51(4):  53-60.  doi:10.12141/j.issn.1000-565X.220359

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The essential cause of the deformation of saline soil in seasonal frozen region is the excess water and salt. Electroosmotic treatment can accelerate the dewatering of soil by driving the salt ions, the excessive water content of anodic soil is also induced subsequently, which will cause seriously freezing deformation. In this work, a set of comparison laboratory tests were performed in customized apparatus to investigate the influence of electroosmosis and calcium sodium application (0, 5%, 10%, 15%) on the deformation of sodium sulfate saline soil. The testing results indicate that electroosmosis incorporated with calcium chloride can dramatically improve the soil’s conductivity and drainage rate. Compared with sole electroosmotic treatment, the accumulative drainage of soil treated with electroosmosis-calcium chloride increases by more than 35%. Moreover, the surplus Na⁺ and SO₄^2- ions migrate to cathode and anode respectively, and exit with water flow, resulting in the significant decrease of frost heave and salt expansion. The free Ca²⁺ ions involved in anodic electrolyte migrate to cathode under the external electric field and react with OH^- ions. The obtained Ca(OH)₂ serves as cementing agents and improves the integrity of soil matrix. Also, the residual Ca²⁺ ions deported to cathodic area react with some soluble silicate, forming the calcium silicate hydrate (C-S-H) which coate on soil particle surface and increases the internal friction angel of soil. After electroosmosis-calcium chloride treatment, the microstructure and resistance to deformation of sodium sulfate saline soil were obviously improved. And the mass concentration of 10% calcium chloride solution achieves the best reinforcement. By comparison with sole electroosmosis treatment, the drainage volume increases by 70%, and the shear strength of cathodic soil increases 27.1 kPa, the freezing deformation decreases by 65.1%. While, once the mass concentration of calcium chloride exceeds 10%, the soil shear strength and drainage decrease because of the blockage of electroosmotic channel and corrosion of electrodes, resulting in the increment of soil deformation.

Study on Simulation and Design of Natural Ventilation for Patio Space of Multi Corridor Inpatient Building in Humid and Hot Areas



ZHANG Wenyu, ZHANG Chunyang, WANG Yicheng

2023, 51(4):  61-70.  doi:10.12141/j.issn.1000-565X.220361

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Due to the special climate in the humid and hot areas of China, the ventilation of hospitals through air-conditioning system leads to huge energy consumption. Most public spaces in the inpatient department of a hospital can and should be naturally ventilated to meet the thermal comfort needs of users, improve indoor air quality, and effectively save energy and reduce consumption, given proper categorization and layout. Patio is a common climate adaptive space for buildings in humid and hot areas. The article took Guangzhou, a representative city in the hot and humid region of China (23.1°N, 113.3°E), as the research location and the corridor-type inpatient building as the research object. Through the CFD simulation experiment of designing a hospital inpatient building model and analyzing the suitable periods for natural ventilation in the hot and humid region throughout the year, the study explored the influence of design elements of courtyard space on the natural ventilation performance of the public space in the nursing unit of the multi-corridor inpatient building. The results show that compared with the building without patio, the multi corridor inpatient building with the patio space can effectively improve the natural ventilation performance of the nursing unit public space of the multi corridor inpatient building; By setting a reasonable plan form, position, and height for the courtyard, the public space of each nursing unit on all levels of the multi-corridor inpatient building can achieve natural ventilation that meets human comfort. By setting the position of the air inlet on the ground floor of the inpatient building reasonably, the potential for natural ventilation throughout the year can be increased. For example, in the Guangzhou area, besides the south-facing direction, there is a higher frequency of natural wind in the southeast, northeast, and north directions. Therefore, in addition to the south-facing direction on the ground floor of the building, it is also appropriate to set some air inlets in the southeast, northeast, and north directions to increase the potential for natural ventilation throughout the year.

Research on Audio-Visual Integration Based on Architectural Acoustic Simulation



SUN Haitao, YANG Yu

2023, 51(4):  71-79.  doi:10.12141/j.issn.1000-565X.220209

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In the article, the multi-channel recording signal of Mozart's Symphony No. 40 was selected as the source dry signal, and the Tianjin Cultural Center concert hall was used as an example to simulate the sound field using the architectural acoustics simulation software ODEON. The symphony orchestra was divided into 49 point sound sources according to musical instrument, corresponding to the directivity of each musical instrument respectively. Five typical receiving point positions were set in the audience seat area, and the binaural impulse response from each sound source point to the receiving point was calculated respectively, then use binaural impulse response to convolve with the instrument signal corresponding to each sound source point, and finally the 49 resulting audio signals were synchronized and played together to synthesize the multi-source audible signal of the orchestra. At the same time, according to the traditional audibility method, set a point sound source in the center of the symphony orchestra, calculate the binaural impulse response from the point sound source to the receiving point, and then use binaural impulse response to convolve with the signal of the symphony composed of 49 dry signals and mix it into a single sound source audible signal. In terms of vision, firstly, the 3D model of the concert hall was established in sketch up and the real materials were given to each surface. The model of sketch up was output to the VR virtual reality simulation software SIMLAB composer, in which the parameters such as light, material and environment were adjusted. The virtual model was rendered and baked with adjusted information parameters to obtain a better sense of immersion. HTC VIVE Cosmos glasses were used to output VR virtual scenes and to simulate the three-dimensional vision of the hall. During the architectural acoustics audio-visual experiment, the subjective evaluation differences of Reverberance and ASW (Apparent Source Width) of audible signals convoluted by multiple sound sources and single sound source were compared under the condition of with or without VR visual signal. The experimental results show that the audible signal convoluted by multiple sound sources can significantly improve the Reverberance and ASW, and the improvement degree of different receiving points is different. Due to the significant difference in sound quality between the single-source and multi-source audible signals, the listening test participants in the architectural acoustics and audiovisual experiment focused more on the improvement of spatial sound quality. The addition of VR visual signals did not significantly improve the subjective evaluation results of the audible signals.

Traffic & Transportation Engineering

Analysis and Prediction of Rear-End Conflicts on Road Sharp Curves



WANG Yonggang, CHEN Junxian, ZHENG Shaoya, et al

2023, 51(4):  80-87.  doi:10.12141/j.issn.1000-565X.220430

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In order to realize the active prevention and control of rear-end collision on sharp curves, a dynamic prediction method of rear-end conflicts was proposed based on converged multi-source data. In this study, firstly, a model for distinguishing rear-end conflicts on sharp curves and a classification criteria of conflict level threshold were proposed by using the vehicle traveling data collected by drones and millimeter wave radar. The spatial distribution characteristics of such conflicts on sharp curves was subsequently analyzed. Then, 13 variables related to traffic flow characteristic such as vehicle type, ratio of large vehicle, and speed difference between sections were selected as input variables, and dynamic combined prediction models of rear-end conflicts on sharp curves with BP neural network, random forest and support vector machine algorithms were constructed based on particle swarm algorithm, respectively. The prediction performance of each prediction model was evaluated based on confusion matrix and area under curve, and the black box interpretation method was used to analyze the significant influence variables and the probabilities of rear-end conflicts occurrence. The results show that the TTC values of rear-end conflicts on sharp curves are smaller than those on flat or normal curved sections, and such conflicts are more serious on the gentle curve exit sections, and the conflicts risk on the inner side of the curves is the highest; the particle swarm algorithm- random forest model has the best performance in predicting the rear-end conflicts, with a sensitivity of 90.70%; the impact of average vehicle headway on rear-end conflict in sharp curve sections is the most significant. When the average vehicle headway is around 25 meters, the probability of conflict is the lowest. Factors such as mean centripetal acceleration and mean velocity also have a significant influence on it.

Influence Characteristics and Action Mechanism of Tunnel Traffic Signs Based on Driving Behavior



ZHAO Xiaohua, DONG Wenhui, LI Jia, et al

2023, 51(4):  88-100.  doi:10.12141/j.issn.1000-565X.220251

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Reasonable setting of tunnel traffic signs can alleviate the “spatial-temporal tunnel effect” caused by the special environment of tunnels to a certain extent. This paper studied the influence of traffic signs (speed limit signs and exit warning signs) on driving behavior in highway tunnels. Firstly, it selected long tunnels as experimental sections, obtained fine-grained microscopic behavioral data of drivers through driving simulator, and constructed a linear mixed effect model considering the influence of random effects to reveal the influence characteristics and mechanism of traffic signs on driving behavior in tunnels. The results show that: there are differences in the effects of traffic signs on driving behavior in different influence zones; installation of speed limit signs inside the tunnel can reduce the probability of accident risk to a certain extent and the repeated setting of speed limit signs can improve drivers’ maneuvering ability to a certain extent; the setting of speed limit signs and exit distance warning signs inside the tunnel can help improve drivers’ spatial control ability and driving comfort. Among them, the installation of tunnel exit distance warning signs in the impact zone of less than 1km from the tunnel exit helps to improve the driving comfort of drivers; the installation of tunnel exit distance warning signs in the impact zone of 2 km and 1.5 km from the tunnel exit can improve the vehicle control ability and at the same time make drivers have a higher driving speed. In addition, driving behavior under the effect of tunnel traffic signs is influenced by driver’s gender, age, driving experience and other characteristic attributes, with male drivers having a lower driving risk.

Traffic Data Imputation Based on Self-Supervised Learning



ZHOU Chuhao, LIN Peiqun, YAN Mingyue

2023, 51(4):  101-114.  doi:10.12141/j.issn.1000-565X.220237

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In the regional highway network, there are numerous toll stations generating massive amounts of data on a daily basis. However, due to equipment and network issues, there may be delays in data transmission for some stations. In such cases, the transmitted data may not be sufficient to meet the requirements for real-time traffic flow prediction. To achieve real-time traffic data imputation and dynamic traffic flow prediction, this paper firstly proposed a method for data imputation of highway traffic flow data based on self-supervised learning, which adopts time series model based on attention mechanism (Seq2Seq-Att). Then the self-supervised learning method was used to train the model. Finally, the reliability of the method was verified by taking 80 toll stations in the highway network of Guangdong province as an example. The results show that the method in this paper can flexibly capture the missing pattern in traffic data and give a reasonable value according to the internal correlation of the data. This method is generally superior to other methods and has good performance under different missing rates. The overall MAPE is about 17.7% and the WMAPE is 12.8%. In the case of high missing rate, this method has obvious advantages over other methods. The results of traffic volume prediction indicate that the prediction accuracy of traffic flow prediction using the data completed by this method is close to the situation of using complete data.

Comprehensive Optimization of Track Scale Configuration of Intermediate Station and Train Timetable of High-Speed Railway



ZHENG Yajing, MA Zihan, CHANG Xiaoting, et al

2023, 51(4):  115-123.  doi:10.12141/j.issn.1000-565X.220329

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The track scale of high-speed railway intermediate station is an important factor affecting the line carrying capacity and transportation efficiency. In the planning stage of the high-speed railway line, it is difficult to predict the long-term passenger flow. Therefore, after a period of operation, it is often necessary to update the track scale of intermediate stations along the line by building side tracks or platforms. For high-speed railways, the trains running on their lines are all electric multiple unit trains, with short track intervals, high departure densities and no long dwell time at intermediate stations. Therefore, high-speed railways generally operate in fast-in and fast-out operation mode. At the same time, the construction and operation of high-speed railways have a high cost attribute. The article constructed a comprehensive optimization model with the renovation construction cost and total travel time as the evaluation objectives and the coupling relationship between the train timetable and the number of intermediate station tracks as constraints. On the basis of linearizing the constraints, the model was solved with the help of commercial optimization software GAMS with CPLEX solver. The results of the calculation example show that the comprehensive optimization of the track configuration of the intermediate stations and train timetable can not only determine the stations for train overtaking and turning back in the timetable but also meet the future passenger demand to the greatest extent at the lowest construction cost.

Dynamic Damage Characteristics of Large Section Tunnel Lining Under Seismic Load



HUANG Juan, LONG Haofeng, ZHOU Shijie, et al

2023, 51(4):  124-134.  doi:10.12141/j.issn.1000-565X.220391

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Based on the dynamic damage characteristics of concrete material, this paper established an elastoplastic damage constitutive model, which was applied to a tunnel project with large section in a strong earthquake area. It analyzed the seismic response and dynamic damage law of tunnel structure under different incident directions of seismic waves, seismic wave intensity and surrounding rock conditions, and discussed the seismic damage characteristics and failure mechanism of large section tunnel structure. The results show that the principal stress and acceleration responses of the lining are similar under vertical and horizontal incidence conditions, but the stress and acceleration responses of the lining structure under horizontal incidence conditions are more intense than that under vertical incidence conditions. The dynamic damage of the lining at horizontal incidence is much greater than that at vertical incidence, and the dynamic damage is mainly concentrated at the arch waist and the foot of the wall. The surrounding rock conditions have significant influence on the tensile principal stress response and dynamic damage of the tunnel lining structure. The maximum tensile stress of the lining structure under V-level surrounding rock is 5.7 times of that under IV level surrounding rock. The seismic response and dynamic damage characteristics of tunnel structure are also affected by the intensity of seismic waves. With the increase of seismic wave intensity, the peak value of stress, acceleration response and the maximum amount of dynamic damage show a nonlinear increase trend, and the dynamic damage intensifies and gradually expands outward from the waist and the foot of the wall. In the seismic design of soft rock tunnel in strong earthquake area and the post-earthquake reinforcement and repair during operation, attention should be paid to the parts where the dynamic damage is concentrated.

High-Throughput Calculation for Meso-Contact of Asphalt Mixture Skeleton



TANG Cheng, WANG Duanyi, YUN Di, et al

2023, 51(4):  135-144.  doi:10.12141/j.issn.1000-565X.220514

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In order to realize the high-throughput calculation of meso-contact for asphalt mixture skeleton, this paper firstly put forward two contact calculation methods, the neighbor list method and the improved window search method, and then four asphalt mixtures AC13, AC16, OGFC13 and SMA13 were used to compare the difference in calculation accuracy and efficiency among two new methods and exhaustive method, window search method and iPas software, and the range of image resolution that can achieve the balance of calculation speed and accuracy was investigated using virtual specimens. Finally, the applicability of the high throughput calculation method was verified. The results show that neighbor list method can avoid the redundant contact calculation of contact aggregate pairs with the exhaustive method, and the improved window search method can accomplish the purpose of a one loop sweep of the traditional window search method by morphological expansion processing. Neighbor list method, exhaustive method, window search method, improved window search method and iPas software have the same accuracy although there are differences in calculation principles. The order of computational efficiency of different calculation methods is: neighbor list method > exhaustive method > Improved window search method >iPas software > window search method. The decrease of image resolution will improve the speed of contact calculation but reduce the accuracy of contact point calculation results. Considering the requirements of both accuracy and efficiency, a balance of calculation speed and accuracy can be realized when the image resolution range is 0.05~0.075 mm/pixel. The neighbor list method can effectively realize the high throughput characterization of meso-contact of asphalt mixture skeleton.