Advanced Materials Research Vols. 243-249

Abstract: In order to obtain blasting vibration attenuation rule of a soil-rock blasting, the basis theory may provide for later blasting construction, after the blasting vibration monitoring of blasting construction ,the correlation coefficient K and α can be obtained by sodev’s empirical formula and its linear correlation coefficient is significant,the result has guiding significance in blasting construction. Regression formula error is between 6% to 23% in vertical, between 17% to 25% in horizontal radial and between 4% to 25%. If inflection point is eliminated, and the blasting is safety to the nearby buildings. The analysis results has its guiding significance.

Abstract: The reason influence blasting is consist of the quality of mixed ANFO explosion and management etc. Mixed ANFO explosion get the optimum proportion of diesel, field experiment is done, the biggest detonation velocity,smallest detonation velocity and average detonation velocity , detonation change along with the diesel allocated proportion increasing. Optimum proportion of diesel is 5.0%, it has important significance for blasting construction.

Abstract: This paper selects three different fibers: short-cut mineral fiber, mineral cotton fiber and lignin fiber, through the laboratory test to analysis the homogeneity and way-use performance of fiber SMA. Contrast test results show that the homogeneity of adding mineral cotton fiber and lignin fiber of SMA mixture is nearly at the same degree, which are all better than adding short-cut mineral fiber. Adding short-cut mineral fiber with SMA has poor water stability, but the high temperature stability is the best; At the same time, the homogeneity of the fiber asphalt mixture in this paper has a certain effect with the road performance, but impacts little with the absolute value of it.

Abstract: In the paper, the method of prolong aging time in oven was adopted to get different aging degree asphalt, such as base asphalt and modified asphalt. Firstly, the mass loss percent during water cooking and adhesion grade were tested to evaluate the adhesion property. Then, the influence regularities of adhesion property were analyzed due to asphalt aging. Finally, the relativity between mass loss percent and adhesion grade was carried out. It is found that adhesion grade is falling, and mass loss percent is increasing with the adding of asphalt aging degree. And the study result also proves that modified asphalt has better adhesion performance than base asphalt. The two evaluation parameters have stabilization relativity. The mass loss percent is advised to use to evaluate adhesion performance for better objectivity.

Abstract: Generally speaking, the asphalt concrete pavement will be affected by the temperature and aging when it is in the use, which makes the modulus of asphalt mixtures change as non-uniformity gradient. This paper assumes the different changes on the modulus of surface layer with different gradient and then researched the mechanical characteristics of asphalt concrete pavements with cracks and no cracks by the finite-element method . Moreover, the research focused on the stress and K I & K II of the asphalt concrete pavements affected by the modulus of surface layer changed as non-uniformity gradient. The results demonstrated that the larger the gradient on the modulus of the surface layer,the bigger the tensile stress and K I and K II of the asphalt concrete pavements, and K II is even much bigger than K I. Consequently, it is of great importance to take into account the effect of the modulus of surface layer changed as non-uniformity gradient. It also makes a great significance for the revision of pavement design and the analysis of pavement damage mechanism.

Abstract: The research on planning method of the frontier regional road network can be a good method to solve the pressure of border highway network, which comes from the transportation demand of combat readiness. Based on the traditional traffic demand forecasting method of "the four stages", combined with the characteristics of the frontier regional traffic demand, this paper establishes the forecasting models for tactical and strategic traffic demand. According to the militarization of the frontier regional road network, the concept of military importance degree is proposed, and the node importance degree model of highway network is improved. Moreover, the best-scale method and gradual-adjustment method are selected as the optimization of the frontier regional road network planning. Finally, the traffic demand forecast, the node important degree calculation and the optimization of road network layout are studied, which are based on the simulation of the frontier regional road network, and the planning model’s validity of the frontier regional road network is examined.

Abstract: Deflection is the important index of asphalt pavement design and the final acceptance. Using double circular load of Design Specification and four circular load of Benkelman test vehicle, the deflection was analyzed with four kinds of common pavement structures, the results show that the deflection of theoretical calculation was the Benkelman beam test 55%-75%, but Design Specification uses the F coefficient which less than 1 to correct the difference, the two have had the contradiction. The deflection of two and three axles load mode were analyzed, and compared with the axle load conversion coefficient C₁. The result could provide the reference of axle load conversion and the correction coefficient for the pavement design.

Abstract: Stable structure of subgrade of railway is an important foundation for safety of train. Rising of speed and heavy transport tasks accelerate deterioration of ballast and increase disease of subgrade. It is more important how to detect and maintain the condition of ballast and subgrade highly effective, faster and without any destruct. In recent years, the ground penetrating radar has been an effective method for detecting and evaluation ballast and subgrade. This paper present application of detecting and evaluation ballast and subgrade by using the train-mounted-multicenter ground penetrating radar(GPR), data processing and interpretation, acknowledge and some problem.

Abstract: Though there have been some experimental studies to discuss laws of grounding shape and grounding pressure, the acknowledged mathematics model has not established. In order to discuss the law of tire ground pressure distribution, pressure distribution models of round rectangles grounding shape and ellipse grounding shape are advanced differently. Parameters setting method and 3-D graph of different ground pressure distribution are presented, and expressions of ground area, mean ground pressure, most ground pressure and the normal stress on the ground are deduced. Results show that the grounding shape of tire is close to ellipse or rectangle as load varying, and the distribution of grounding pressure express convex or concave under different tire pressure and loading.

Abstract: The water content in the subgrade changes easily as the variation of the environment water, which causes the strength attenuation of the subgrade. It is harmful to the stability of subgrade slope. Strength decay pattern of silt soil in yellow river alluvial plain is studied through the laboratory test. And then the finite element software GEO-SLOPE is used to calculate coefficient of stability under different conditions. Results show strength indexes of silt soil are maximum in the optimal water content, and the change of the water content would cause strength attenuation. The stability of subgrade slope decreases as the strength degradation, while the evolution is different, which is semi-parabolic in the lower subgrade but rectilinear in the higher subgrade. Seismic load leads to stress concentrate at the slope, combined with the strength attenuation the landslide is easily to take place.