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Zhang J.,Chinese Research Institute of Highway | Zhang J.,Key Laboratory of Transportation Tunnel Engineering | Liu S.-W.,Chinese Research Institute of Highway | Pu H.-F.,Missouri University of Science and Technology
Advances in Materials Science and Engineering | Year: 2015

With a large number of applications of conventional technique for geosynthetic-reinforced and pile-supported (GRPS) embankment (called CT embankment), many deficiencies have been exposed. In view of the deficiencies, an improved technique, fixed-geosynthetic-reinforced and pile-supported embankment (called FGT embankment), is developed. To investigate the performance of the FGT embankment, the comparison analyses and parametric studies are conducted by Finite Element Method (FEM). The influencing factors investigated include elastic modulus of soil, tensile stiffness of geosynthetics, pile length, pile spacing, and pile elastic modulus. In addition, the cost evaluation for the FGT embankment and CT embankment is also made. The results show that the FGT embankment can significantly reduce the settlement and differential settlement, enhance the stability, and provide an economical and effective measure for the construction of high embankment at the bridge approach. © 2015 Jun Zhang et al.

Yang H.,Chongqing University | Yang H.,Key Laboratory of Transportation Tunnel Engineering | Wang H.,Chongqing University | Zhou X.,Chongqing University
Rock Mechanics and Rock Engineering | Year: 2015

The accurate prediction of rock cutting forces of disc cutters is crucial for tunnel boring machine (TBM) design and construction. Disc cutter wear, which affects TBM penetration performance, has frequently been found at TBM sites. By considering the operating path and wear of the disc cutter, a new model is proposed for evaluating the cutting force and wear of the disc cutter in the tunneling process. The circular path adopted herein, which is the actual running path of the TBM disc cutter, shows that the lateral force of the disc cutter is asymmetric. The lateral forces on the sides of the disc cutter are clearly different. However, traditional solutions are obtained by assuming a linear path, where the later forces are viewed as equal. To simulate the interaction between the rock and disc cutter, a simple brittle damage model for rock mass is introduced here. Based on the explicit dynamic finite element method, the cutting force acting on the rock generated by a single disc cutter is simulated. It is shown that the lateral cutting force of the disc cutter strongly affects the wear extent of disc cutter. The wear mechanism is thus underestimated by the classical model, which was obtained by linear cutting tests. The simulation results are discussed and compared with other models, and these simulation results agree well with the results of present ones. © 2015 Springer-Verlag Wien

Wang B.,Southwest Jiaotong University | Wang B.,Key Laboratory of Transportation Tunnel Engineering | Wang B.,Hong Kong Polytechnic University | Xu Y.,Hong Kong Polytechnic University | Li Y.,Southwest Jiaotong University
Journal of Transportation Engineering | Year: 2016

Threats of wind gusts on the safety of road vehicles have been reported around the world, and extensive studies have been carried out to find the accident speeds of road vehicles under a sudden crosswind. However, most previous studies assume that the angular displacements of the vehicle are small and the mass moments of the vehicle remain unchanged during the overturning of the vehicle, yielding a quasi-linear safety analysis of a road-vehicle under a sudden crosswind. This study aims at a nonlinear safety analysis of a running road vehicle under a sudden crosswind by establishing nonlinear equations of motion of a wind-vehicle system. The assumptions adopted in the previous studies are no longer required, and tires can lose or resume contact with the ground. Wind loads on the vehicle are updated with the consideration of the time-varying attitude of the vehicle. The numerical example shows that the proposed nonlinear analysis procedure is more rational than the currently used approaches for progressive instability and the accident vehicle speed of road vehicles. © 2015 American Society of Civil Engineers.

Wang J.H.,Nippon Oil Corporation | Zhang W.J.,Tianjin University | Zhang W.J.,Key Laboratory of Transportation Tunnel Engineering | Guo X.,Tianjin University | And 2 more authors.
Tunnelling and Underground Space Technology | Year: 2015

In this paper, the effects of segmental joints, dimensions of segments, and ground conditions on buckling of the shield tunnel linings under hydrostatic pressure are studied by analytical and numerical analysis. The results show that radial joints have significant impacts on the buckling behavior: the shield tunnel linings with flexible joints buckles in a single wave mode in the vicinity of K joint, while those with rigid joints buckles in a multi-wave mode around the linings. Hydrostatic buckling strength is found to increase with the flexural rigidity of the radial joint and the thickness of segment increasing. This study shows that ground support increases the buckling strength dramatically, while earth pressure reduces the capacity to resist hydrostatic buckling. The tunnel linings during construction are found to be easier to buckle than that during operation. Meanwhile, the buckling of tunnel linings is studied by theoretical analysis of buried tube buckling. © 2015 .

Zhang J.,Key Laboratory of Transportation Tunnel Engineering | Zhang J.,Chinese Research Institute of Highway | Zheng J.,Huazhong University of Science and Technology | Zhao D.,Chinese Research Institute of Highway | Chen S.,Key Laboratory of Transportation Tunnel Engineering
Science China Technological Sciences | Year: 2015

Vehicle bumps at a bridge approach caused by the differential settlement between a bridge and an adjacent backfill embankment are one of the most difficult problems in geotechnical engineering. Large vehicle bumps make drivers uncomfortable and cause large impact loads on vehicles and the bridge abutment. A new ground-improvement technique called fixed-geosynthetic-reinforced and pile-supported embankment (FGT embankment) was developed and used to alleviate vehicle bumps at a trial bridge-approach site located in central China. To distribute the differential settlement between the bridge and adjacent backfill embankment over a long transition zone, the following three techniques were used at the trial bridge-approach site: (a) the FGT embankment, (b) conventional geosynthetic-reinforced and pile-supported embankment (CT embankment), and (c) geosynthetic-reinforced embankment without piles (GR embankment). The performance of all three techniques in the field trial was investigated by field measurements involving earth pressure cells, geosynthetic deformation sensors, and settlement gauges. The FGT and CT embankments exhibited better performance than the GR embankment. Compared with the CT embankment, the FGT embankment was more effective at ground improvement. At an elevation of 4.0 m from the base of the embankment, the pressures below the geosynthetic were smaller than those above the geosynthetic at the closest measurement point. The difference between the pressures between above and below the geosynthetic tended to increase with the embankment height. © 2015 Science China Press and Springer-Verlag Berlin Heidelberg

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