Applied Mechanics and Materials Vols. 178-181

Abstract: With the project of mining 701 Working Face of Baojianshan Coalmine of Jingyuan Coal Industry Group undermine special railway as a background, the authors predict ground subsidence law caused by routine comprehensive mechanized caving coal mining method and back filling method with elastic-plastic nonlinear FEM method. By different exploitation methods, development law of horizontal displacement, vertical displacement, shift angle of strata during mining is given. According to predication by FEM method, the maximum vertical settlement of subsidence area near railway subgrade is 7cm, which is caused by mining 701 Working Face. The in-situ monitoring results were essentially identical with the FEM predication value, this indicates that FEM predication is reliable. The rehabilitation technical measure of railway bed and deformation monitoring scheme of railway during long-term operation are advised.

Abstract: There are three soft ground types in the joint highway of Jiaozuo-Gongyi Yellow River bridge in Henan province: shallow, sandwich and deep layers. By analyzing the observation date, the horizontal displacement characteristics of alluvial flat soft ground under embankment are studied. The settlement is the dominant deformation in construction time, but the mainly factor that controls construction speed is horizontal displacement of the weakest layer. The failure mode of sandwich and shallow type grounds is different to the circular one in deep type ground, so the translation mode is put forward. Due to the uniform in thickness and spaces of alluvial flat soft ground, the horizontal displacements are quite different at both sides of subgrade.

Abstract: Crack resistance is an important indicator to evaluate asphalt mixture performance, so the critical fracture criterion of asphalt mixture was deeply studied based on semi-circular bending test under different temperature. The results show that Semi-circle bending test is suitable to evaluate the crack resistance of asphalt mixture; fracture toughness Jc is a more reasonable indicator of the fracture criterion for asphalt mixture than Kc; The fracture toughness calculation model of single specimen built in this paper can simplify the semi-circular bending test operation, and can reduce the number of test specimens.

Abstract: Load stress, which is caused by traffic loading, is important parameter used in the analysis of the new pavement design. In order to study the load stress of lean concrete base in the asphalt pavement, first of all, three–dimension finite element model of the asphalt pavement is established. The main objectives of the paper are investigated. One is calculation for load stress of lean concrete base, and the other is analysis for relationship between load stress of lean concrete base and parameters, such as thickness, modulus. The results show that load stress of lean concrete base decreases, decreases and increases with increase of base’s thickness, surface’s thickness and ratio of base’s modulus to foundation’s modulus respectively. So far as the traffic axle loading is concerned, it has a significant impact on load stress of lean concrete base, and it can be seen from results that when load is taken from 100kN to 220kN, load stress increases quickly with the increase of the traffic axle loading.

Abstract: The Hu-Yang expressway, the first one in mountainous area in Shannxi province, has two conflicts in construction. One is the tunnel abandoned dreg is difficult to place, and cause ecological environment damage; the other is the project needs so much filler and sand which is scarce along the line. The tunnel abandoned dreg for rock-fill embankment and manufactured sand is designed to solve the problems. Slope greening, crushed run rock in certain range of roadbed and back of the retain wall and compaction control method of rock-fill embankment are discussed. And in view of technical and economic aspects, the application of manufactured sand is also studied. It decided to adopt manufactured sand in the Hu-Yang expressway for the first time in highway construction in Shaanxi province.

Abstract: The research methods of Cohesive Zone Model (CZM) are introduced and the parameters of cohesive zone model in ABAQUS software are calibrated based on the cohesive constitutive model determined by the fracture energy. Besides adopting exponential cohesive zone model, this paper applies a bilinear one to simulate the crack propagation of a simply supported single-edge notched concrete beams SE(B) (Mode I) and make comparisons with experimental result. Finally, the results represent effectiveness of the effective modulus and the special advantage in term of failure of fracture based on the cohesive zone model, which is of directly guiding significance for achieving a deep going understanding of crack propagation.

Abstract: Premature rutting due to high temperatures and heavy loads has been a major distress on flexible pavements in Pakistan. One of the main causes of this early rutting is the available asphalt binders, which are still graded by using penetration grading system. The penetration grading system is based on empirical tests and does not link with performance. To improve the quality of the flexible pavement and to avoid the premature rutting the performance based testings were conducting in laboratory. This study evaluated performance graded (PG) binders for use in pavement construction in the country. Five different penetration graded asphalt binder, typically available in the country were graded according to PG system. The performance grades (PG) for all binders were determined based on DSR and BBR results. The two same penetration grades ARL60/70 and NRL 60/70 have different PG grades. The two different penetration grades ARL60/70 and NRL 80/100 have same PG grade. The results show that the local binders are very soft due to which they performed poorly at high temperatures and prone to severe rutting.

Abstract: The semi - rigid base pavement disease characteristics, the use of finite element model of comparative analysis of different diseases at the deflection basin, obtained disease and the shape of the deflection basin, and thus can be used (FWD) measurement deflection basin to determine the size and depth of repair.

Abstract: In the construction process of the port highway, riprap quantities are difficult to accurately predict which has bought great difficulties to the riprap vessel to organize construction. Besides, it results in a huge waste of riprap in the construction of the port highway, even leads to the riprap vessel aground during construction process. After predicting the undersea terrain model, we can propose plane model and the basic algorithm .By using the algorithm, it is easy to calculate the amount of engineering in the riprap and the undersea terrain changes after the riprap. So we can get a reasonable dumping location. Finally, compared the predicted results with measured results of the seabed elevation after the riprap, the outcome is basically the same. It provides an effective tool for the construction process of the port highway.

Abstract: The use of Reclaimed Asphalt Pavement (RAP) has been enormously increased from the last two decades. In fact using RAP in pavement construction has now become common practice in many countries. Using RAP not only economical and environmental friendly but also preserve the natural resources and similar or even better in structural performance than virgin asphalt mixtures. This paper presents an experimental study to evaluate the effect of various types and percentages of RAP on the properties of asphalt mixtures. Four mixtures, which were the combination of two different virgin aggregates and two different RAP sources were studied in this research. The mixtures were designed by Marshall method at a wide range of 0 to 100% RAP blends. RAP material was blended with virgin aggregate such that all specimens tested had approximately the same gradation. Mixtures containing RAP showed significant variability and the variability increased with the increase in RAP content.