Applied Mechanics and Materials Vols. 178-181

Abstract: A method for modulus back analysis of pavement structure based on particle swarm optimization (PSO) is presented. The principle and implementation process of the method is detailed. Some theoretical and experimental data of pavement deflection are selected to test its performance. The contrastive analysis of the modulus inversion results of the proposed method and some representative pavement modulus back calculation softwares using the same deflection data is also performed. The results show that the presented method has relatively high identification accuracy and notably computational stability, which can effectively reduces the influence of initial tentative value on inversion results of pevement modulus.

Abstract: In view to the gangue characteristic and the roadbed padding's essential requirements, the improving experiments for gangues mix the clay in four coal mines along the route to the Jidong highway Huojia section were carried out. It has been studied that the compaction test, the oedometric test, the California bearing test and the direct shear test for coal gangues mixed with clay and them in proportion of 2:1, 3:1, 4:1 respectively. The result indicated the compression modulus, the CBR values and the shearing strength of the coal gangue have been increased in varied degree. It was found that its intensity satisfies the design requirement of roadbed by application of the coal gangue mixed with clay as road filling

Abstract: The joint road of Jiaozuo-Gongyi Yellow River bridge in Henan province is built on the Yiluo River alluvial flat soft ground. The total length treated with packed drain well is 1384 meters. To guarantee project quality and summarize the deformation rules of the alluvial flat soft clay, 15 representative sections are selected and 38 settlement plats are set. The observation has been lasting more than two years from construction to precompression term. By analyzing the characteristic of the soft clay, the settlement type of precompression, the settlement standard of post-construction and the settlement rate of precompression, that the precompression term is not needed is put forward on the alluvial flat soft ground treated with packed drain well.

Abstract: Based on natural climate characteristics, road building conditions and traffic situations in African desert district, the problem of typical structure of asphalt pavement was studied by data investigation. Considering the principle of road structure and design, the optimal values of thickness and materials of structural layers were recommended. The research results establish a guideline for the design of asphalt pavement structures and provide a sufficient technology support to develop pavement infrastructures in African desert districts.

Abstract: A finite element model considering the high-speed train excitation loads, track structure, vibration reduction measures, station structure, characteristics of foundation soils was established to study the problem of vibration in the underground Futian hub of Guangzhou-Shenzhen- Hong Kong high-speed rail. The first 200 natural frequencies of the station are all within 40Hz, the vibration energy concentrates mainly in the second and third floors, in the form of bending vibration mode; the modes of local orbital plate mainly accounts for vertical vibration, and the lowest frequency is near 26Hz.The additional displacement and stress induced by vibration is not great in general, vibration energy of the structure is mainly concentrated in the band of 15~20Hz. When the train passes by at a speed of 200km/h, without damping rubber pads, the maximum vibration level at upper floors is 57.9 dB, while with damping pads under the orbits the vibration level decreases by 5~6dB,which is a significant effect.

Abstract: It researches ulter-thin overlays and bonding characteristics of the original road with a large number of laboratory test simulation tools in the thesis. From different spread quantities and different temperature of the adhesive layer shear strength test, you can get the layers of oil content should not be less than 2.5% of SBS modifier, the emulsified asphalt solid content should not be less than 60%. Through factor analysis of sticky layer of oil spread quantities, you can get the ultra-thin overlay layer with voids in asphalt mixtures VV and significant influence of the original pavement structure depth TD on interlayer bonding properties, the design range of appropriate void UTFC10 ultra-thin overlay is 8 ~ 12 %, the range of oil spread quantities of sticky layer is 0.8 ~ 1.2 L/m².

Abstract: When we make design of mixture ratio, we always use normal equation method (NEM), but the solution value of that method may doesn’t meet our demand. When we use the new method that proposed in this paper, we can solve the problem. The new method makes an improvement for NEM. By iterative algorithm, the new method uses the gradation data calculated by NEM as initial target value, canceling the relevant aggregate if the result of proportion is negative, and setting the gradation to the boundary value if the target value goes beyond limits. According to the adjusted object value, using NEM again, the new aggregate proportion can be solved. Then the new gradation of mixture will come into being the next target value. Finally, the accurate result will meet our need. The new improved method has good engineering applicability and high accuracy

Abstract: Based on the multi-layer elastic system theory , it was elicited that the top basic-layer rigidity was a main determinate factor for the surface-layer bottom maximal equivalent stress. And the more basic-layer rigidity, the less surface-layer bottom maximal equivalent stress, showing the more the partake action of basic-layer to the surface-layer bearing axis load. On the side, bearing the same axis load, the stress passed to groundwork from the inverse structure was most compared with the other structures. So the inverse structure has no predominance in the road structure design.

Abstract: Through surveyed engineering geologiy and hydrogeology in-situ,summed up the forms of expression of the freeze-thaw slumping of the soil road cutting slope in seasonal frozen region.By way of combined field tests and lab tests, and studied the influence of the stability of side slopes with seasonal temperature,precipitation,varieties of plants on the slope surface,and locations of the slope during sping-thawing period.This study can provide basis for prevention and treatment of freeze-thaw destabilization of soil road cutting slopes in seasonal frozen region.

Abstract: The corresponding matching relation between the trunk road network distribution and urban layout system development is disclosed through analysis of the correlation between road network structure and urban distribution system development. The fractal theory is introduced for respective introduction to the calculation methods of urban system spatial structure fractal dimension and road network spatial structure fractal dimension, and based on which, the model and the evaluation standard for the matching degree between spatial structure fractal dimensions of the road network and urban network, are established. The researches show that the different calculation methods have their respective advantages and disadvantages and different evaluation results correspondingly, so the discussion from multiple angles and determination of the relatively appropriate fractal dimension matching degree and further evaluation according to the research emphasis become the best way to solve such kind of problems.