In order to study the high temperature rheological properties of high modulus asphalt cement (HMAC) and clarify its definition criteria, firstly, three kinds of HMAC binders were prepared with high modulus modifiers and subjected to dynamic shear rheological test (DSR), zero shear viscosity test (ZSV) and multi-stress creep recovery test (MSCR). Based on the tests and analysis, the complex shear modulus (G*), rutting factor (G*/sin d), zero shear viscosity (ZSV) and unrecoverable creep compliance (Jnr) were taken as technical indexes for the performance evaluation of HMAC. Further, through analyzing the consistency of evaluation results of different evaluation indicators and the correlation between evaluation indicators of HMAC binders and HMAC mixtures, the definition criteria of HMAC binder are eventually given. The test results show that the three high modulus modifiers can improve the viscoelastic properties and high temperature properties of the matrix asphalt, but the modification effect is slightly different; the rheological properties index can basically make a consistent evaluation of the high temperature performance of three kinds of HMAC binders, but the correlation degree is different. The dynamic stability (DS) of the mixture is well correlated with G* (60 degrees C, 10 Hz, 0.1%) (refers to the complex shear modulus measured at 60 degrees C, loading frequency 10 Hz and strain level 0.1%), G*/sin delta (76 degrees C, 5 Hz, 0.1%) (refers to the rutting factor measured at 76 degrees C, loading frequency 5 Hz and strain level 0.1%), zero shear viscosity (60 degrees C) and Jnr. 3.2 (76 degrees C) (refers to the unrecoverable creep compliance measured at the stress level of 3.2kpa and the temperature of 76 degrees C), but the correlation of dynamic modulus (E*) with zero shear viscosity (60 degrees C) and Jnr. 3.2 (76 degrees C) is poor. In summary, it is recommended that HMAC binder should meet both G*(60 degrees C, 10 Hz, 0.1%) >= 60.0 kPa and G*/sin d (76 degrees C, 5 Hz, 0.1%) >= 5.0 kPa, and the definition criteria can be as a design basis for HMAC binder. At the same time, it is recommended to use J(nr 3.2) (76 degrees C) to evaluate the high temperature performance of HMAC. (C) 2019 Elsevier Ltd. All rights reserved.
With the establishment and improvement of highway video surveillance system, traffic target recognition has become a key concern technology in the field of transportation. Aiming at the problem that the existing traffic target recognition technology has poor tracking effect on obscured and blurred targets in continuous motion vehicles, an improved Camshift motion vehicle tracking algorithm is proposed, which predicts the possible position of the obscured target in the current frame by Kalman filtering algorithm, and searches for the target in the position neighborhood of the image frame by Camshift algorithm using color information, combining with the multi-vehicle Tracking chain principle to achieve multi-vehicle tracking. The experiments show that this method can track the moving vehicles effectively in real time, and even when the vehicles are obscured in large proportion, the vehicles can still be tracked correctly, which verifies the effectiveness of this method.
Taking the vegetation species diversity of expressways in Shanxi Province as the research object, this paper selects ten cutting slopes in six operational expressways to carry out the field investigation.Under different geographical locations, geological types of green land, green ecological restoration construction technologies, operation time, and other factors, the difference in Shanxi′s vegetation species richness is discussed. Through the investigation and analysis, it can be seen that the vegetation species diversity of expressway is greatly affected by three factors: geographical location, geological type of green land, and green ecological restoration construction technology, and less affected by the operation time. The vegetation species diversity of expressway is optimal in south Shanxi, the second in middle Shanxi, and the poorest in north Shanxi. The vegetation species diversity of the loess slope is better than that of other poor geological slopes. The diversity of slope vegetation species after applying the ecological restoration technology is significantly better than that of applying the traditional hole planting technology.
Various types of accidents occur frequently in the long-steep slope section of the expressway.Focusing on safe driving risks in the long-steep slope section of the expressway, to further strengthen risk control, this paper uses the analytic hierarchy process to sort the weight of the identified risks and determines the specific influencing degree of each kind of risk. According to the weight sorting result, a targeted precise risk control measure is proposed.
To study and evaluate the slow-released snow-melting property and frost resistance of the self-snow-melting asphalt mixture, the theoretical evaluation method was used to study the self-snow-melting pavement with the VPRSalt content of 3%, 5%, and 7%. Based on the snowfall grade model, it was calculated that the sodium chloride precipitation of VPRSalt self-snow-melting asphalt pavement after 12 h of the snowfall only accounted for 0.57%, 0.55%, and 0.50% of the original storage, indicating that the material has good slow release performance. Using the model to estimate the frost-resistance time and temperature showed that under the condition of light snow, increasing the content of the self-snow-melting material of the asphalt pavement from 3% to 7%, the frost-resistance temperature was lower, the frost-resistance time was longer, and the frost-resistance effect was better. Evaluating the road performance of the VPRSalt self-snow-melting asphalt mixture with the increase of the VPRSalt content from 3% to 7%, the dynamic stability, the low-temperature maximum bending strain, residual strength ratio of freeze-thaw splitting, and residual stability gradually decreased, however, they still met the requirements of Technical Specification for Construction of Highway Asphalt Pavements.
Taking the treatment project of a miscellaneous field with the high-energy dynamic compaction in Lixi Expressway as the research objection, this paper conducted the high-energy dynamic compaction tests for three different miscellaneous fill fields. Using the empirical statistical method, the data fitting of the accumulated settlement of each pit with different tamping times was carried out, and the settlement prediction model of every single tamping pit was established. The research results showed that for the relationship between the accumulated settlement and the number of tamping, the logarithmic formula can be used to express that of shallow tamping pits, which can be normalized to a linear formula, while the exponential formula can be used to express that of deep tamping pits, which can be normalized to a cubic polynomial formula. Relevant formulas can be used for the settlement prediction of similar sites.
Through the field investigation and the hydrogeological survey, this paper comprehensively analyzes the causes and stability of the fill subgrade landslide of the K26+687 — K26+910 section of the Yangquan city diversion project in 307 and 207 lines of the National Highway. It is considered that extremely heavy rainfall is the main external factor causing the landslide, human activity is one of the secondary external factors and the engineering geological condition is the internal basis forming the landslide. Combining the field survey with the stability calculation result of the landslide, the landslide is in an under-stable or unstable state, with an overall creep-compression deformation. The suggestion on landslide treatment was proposed.
The subsidence law of the widened expressway subgrade is analyzed by the simulation calculation of the P1AXIS software and field monitoring respectively. The position of the maximum subsidence of the subgrade determined by simulation analysis and field monitoring is the same, which is about 19 m from the center of the subgrade, and the subsidence meets the design requirements. The subsidence increases with the filling height of the subgrade. The subgrade subsidence rate decreases significantly with the increasing monitoring time and gradually reaches a stable state after monitoring for 135days. The maximum subgrade subsidence by the field monitoring is close to the simulation result, indicating the calculation result is accurate and can be used to guide the construction.
This paper used finite element simulation analysis and field monitoring to determine the influence of each construction factor in the differential settlement of a two-sided widened subgrade.According to the design data, the finite element model was established by the finite element analysis software. The analysis showed that the settlement amount and differential settlement of new and old subgrade increased with the increase of the filling height and the weight of the subgrade filler, but decreased with the increase of the compression modulus of the subgrade filler. From the comparative analysis, the numerical simulation calculation result of the subgrade settlement was basically the same as the field monitoring result,with the same change in the subgrade settlement.
Starting from the actual expressway pavement engineering in Shanxi Province, the CCR model of the data envelopment analysis shows that the effectiveness indexes of the SBS/rubber powder modified asphalt concrete are 0.90 and 0.94 respectively. The calculation results indicate that the rubber powder modifier has a more significant effect on the performance of asphalt concrete pavement. By analyzing the market price, the comprehensive cost per ton of SBS modified asphalt is 15.4% higher than that of rubber powder modified asphalt. In conclusion, the rubber powder modified asphalt concrete pavement is more applicable in the expressway pavement engineering in Shanxi Province and is recommended to be promoted and applied in combination with the actual project in engineering practice.
Through the investigation, this paper collected data on the current state of the comprehensive passenger and cargo transportation hubs of the central urban cluster in Shanxi. By collecting the economic development, population scale, traffic conditions, passenger transportation scale, and other situations of the central urban cluster in Shanxi, combined with the transportation network planning, this paper planned the future distribution of the comprehensive passenger and cargo transportation hubs of the central urban cluster in Shanxi, which can provide a certain reference for similar projects.
To analyze the application effect of CFG pile in soft soil foundation, focusing on a weak filling subgrade, this paper used Midas finite element software to analyze the change in the internal force of CFG pile of the reinforcement of soft soil foundation. The results showed that the pile′s axial force（bending moment） gradually decreased（increased） from the center to the side. At the pile diameter of 0.4 m and the pile spacing of 1.6 m, the minimum internal forces of the pile were 561 kN and 66 kN · m. At the same pile diameter（pile spacing）, the pile-soil stress ratio increased（decreased） with the increase of the pile spacing（pile diameter）. When the pile diameter was 0.4 m and the pile spacing was 2.4 m, The maximum pile-soil stress ratio was 51. When the pile diameter was 0.6 m and the pile spacing was 2.4 m, the maximum load-sharing ratio of the pile was 63.04%. The research results can provide a reference for engineering applications.
Recently, haze weather characterized by particulate matter pollution occurs frequently in Shanxi Province. Source analysis of atmospheric particulate matter shows that dust is one of the main sources of urban particulate matter pollution. Transportation with carrier vehicles increases the number of heavy-duty vehicles,leading to more traffic dust emissions. The pollution phenomenon of "large and pointed-shaped cargo, loose seal,and taking mud on the road" is common in transportation with bulk material carrier vehicles. Therefore, focusing on the spill pollution from operational bulk material carrier vehicles in Shanxi Province, this paper analyzes the pollution situation from the material transportation enterprise source, transportation process, and road environment.From the perspectives of source enterprise, vehicle seal, transportation process, and road environment, measures for reducing the spill and dust are proposed, providing technical support and control measures for the dust pollution caused by the spill in bulk material transportation.
To conduct the experimental analysis and study of the structural bearing capacity of the single-pylon double-plane cable-stayed bridge without the back stay, this paper used finite element software to model and analyze this cable-stayed bridge. The structural static load test was carried out according to Load Test Methods for Highway Bridge. The variations of the stain and deflection values of each section of the main bridge beam and cable pylon under different load conditions and the cable forces generated in the dead load and loading process of the stay cable were analyzed and compared with the theoretical calculation result and the value specified in the design specification. On this basis, the safety and reliability of the structure were tested and evaluated to determine whether the stress condition of the bridge structure meets the design requirements.
Based on the phyllite tunnel in an expressway, this paper studies the deformation law of the initial support and the stress state of the secondary lining during the construction process by two methods,numerical simulation and field monitoring, and the data were compared with the field-measured data. During the excavation, the deformation volume of the tunnel lining support structure was large and tended to be stable after the completion of the construction. The secondary lining mainly bore compressive stress and partial tensile stress, which were all less than the ultimate stress, indicating that the lining structure was stable. The relevant research conclusions have practical significance for guiding similar tunnel construction.
Focusing on the problem that the image process-based detection of road unevenness is easily affected by non-uniform illumination, a detection method for road unevenness with shadow generated by non-uniform illumination is proposed. This method uses the multi-scale Hessian transformation to filter road images, then obtain detailed information on the overall pavement surface contour and potholes under highand low-frequency scales. Hessian matrix eigenvalues and eigenmatrices are used to detect uneven potholes.The effectiveness of this method is verified by the actual road detection results.
This paper analyzes the current situation and development direction of electronic license plates, designs a set of ZigBee-based IoT license plate systems, solves the problem of the high rate of missed detection of ETC during the high-speed passing of vehicles, and realizes each expected function of electronic license plates. The system has a simple structure and low investment, and it is the preferred technical direction of electronic license plates and a vital part of intelligent transportation.
To study the reinforcement effect of the cement-soil mixing pile on the collapsible loess foundation, a model is established by the ABAQUS software according to the design parameter to carry out the numerical simulation and calculation, and the static load test is conducted in the testing section to evaluate the bearing capacity of the composite foundation. It can be seen that both the simulation result and the measured result of the bearing capacity are higher than 150 kPa, which meets the design requirement.The calculated result is slightly smaller than the measured result with a small difference, and it still has a high reference value.
The ventilation calculation of an extra-long tunnel is closely related to the control of the ventilation scale, directly affecting the number and section area of ventilation shafts, the number of jet fans,and then the project cost and operating expenses. In this paper, the optimization of the required airflow for ventilation starts from three aspects: annual decline rate of particulate matter（PM）, required airflow of heavy LNG trucks calculated according to gasoline cars, and proportion control of heavy LNG trucks. Focusing on the investigation of the proportion of heavy LNG trucks, the required airflow was controlled and reduced by nearly 57% after the optimization, which achieves the goals of shortening the construction period, reducing the construction difficulty, and reducing the overall investment.
Focusing on problems of low detection efficiency of pavement cracks, strong subjectivity of crack identification, and identification difficulty of low-contrast cracks, an automatic identification method of low-contrast pavement cracks based on morphological gradient segmentation is proposed. By analyzing the causes of the formation of pavement cracks, this paper studies the preprocessing of pavement images shot by the camera and the desired effect. The application of the Sobel operator method of morphological gradient detection in pavement cracks is studied. By testing the algorithm of the actual collected images of the low-contrast single pavement crack and multiple pavement cracks in complex background, the results verify the effectiveness of the proposed method.
