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Sun S.R.,Hohai University | Lu Y.X.,Hohai University | Zhang S.H.,Jiangsu provincial communication planning and design institute Co. | Wu J.M.,Hohai University
Applied Mechanics and Materials | Year: 2013

The deformation mechanism of surrounding rock during excavation is difficult to stability evaluation for large-span shallow-buried double-arch tunnel. Take Fenghuang mountain tunnel in Suzhou city as an example, the main work and funding are as follow: The measured data in the middle of the tunnel, including settlement on the top of the tunnel and deformation between two lateral walls, were used to calculate mechanical parameters by back analysis method. The obtained parameters were used to calculate the deformation and stress of the main tunnel excavation in the different steps. The rules includes time-space effect during main tunnel excavation, force mechanism of the middle wall and settlement on the ground surface for the surrounding rock in the main tunnel. Finally, the calculated settlement and deformation were compared to the monitoring results. The safety coefficient of surrounding rock for double-arch tunnel was obtained by strength reduction theory. © (2013) Trans Tech Publications, Switzerland. Source

Chen S.,Nanjing Southeast University | Hu J.,Jiangsu provincial communication planning and design institute Co. | Ding J.,Nanjing Southeast University
Advanced Materials Research | Year: 2012

Traditionally, highway engineers use pencil and ruler to lay out lines and curves over contour maps for highway geometry design. Numerous calculations of stopping sight distance, minimum turning radius, and curve alignments are required during the design process to ensure safety, to minimize economic and environmental impact, and to reduce construction costs. Engineers usually perform iterative computations manually during the design process to meet design criteria and environmental constraints. The traditional process of highway geometry design is cumbersome and time consuming. The traditional approach limits engineers from taking a broader perspective in the overall highway geometry design process. Current method of three dimensional (3D) has nothing to do with highway design process. CARD/1 was developed to enhance the learning experience for highway engineers. This tool allows engineers to design the highway efficiently and to modify the design easily. A 3D highway geometry model can be generated by the software at final design to allow engineers to place themselves in the driver's seat and maneuver through the designed highway at maximum design speed. Some key technologies of highway design with 3D-animaion based on CARD/1 was discussed in this paper. © (2012) Trans Tech Publications, Switzerland. Source

Liu L.,Jiangsu provincial communication planning and design institute Co. | Zhang H.,Hohai University
Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology) | Year: 2012

Based on bent-type aqueduct structures, dynamic characteristics and isolation of aqueduct-water coupling systems were studied by using the Arbitrary Lagrangian-Eulerian (ALE) method. Three-dimensional model with fluid-structure interaction was established, and the plate rubber support was installed. Mooney-Rivlin strain energy density model simulated mechanical constitutive relations of rubber material. The natural vibration frequency, displacement, stress of aqueduct structure, and the water sloshing height were calculated in different water depth conditions under earthquake wave action. The results show that the transverse stiffness is less. The application of isolation technology can reduce stiffness of aqueduct structure and extend natural vibration period of aqueduct structure. The fluid-structure interaction increases stress of the internal wall under earthquake wave action. The seismic displacement response of aqueduct structure and the water sloshing height increase by applying the isolation technology, but the application of isolation technology remarkably reduces the seismic stress response and elevates earthquake resistance performance. Source

Yuan A.,Jiangsu University | Zhou Y.,Jiangsu University | Dai H.,Nanjing Southeast University | Sun D.,Jiangsu provincial communication planning and design institute Co.
Chongqing Daxue Xuebao/Journal of Chongqing University | Year: 2012

This paper proposes a new type of prestressed concrete hollow girder based on the summaries of the current studies on longitudinal cracks and hinge cracks. The match prefabricated method is used with shear key at interface to solve the problem of hingle cracks, and the two-way prestressing strand techniques are used to assure the longitudinal load-bearing capacity and to prevent the emergence of longitudinal cracks because of pressure existing at the match interface. In order to reduce the temperature difference between the internal and external of the prestressed concrete hollow girder, drilling holes are carried out at the bottom slab of girder every distance. To ensure the adhesive effect between the girder and deck pavement, we designed grooves at the top slab of girders. The finite element analysis results of a design example show that the pressure stress of bottom slab of girder is about 2.58 MPa and 0.16 MPa, which are effective to avoid the appearance of longitudinal cracks and hinge cracks. Source

Yuan A.,Hohai University | Dai H.,Southwest University | Sun D.,Jiangsu provincial communication planning and design institute Co. | Cai J.,Hohai University | And 2 more authors.
Engineering Structures | Year: 2013

Precst segmental prestressed concrete box beam bridges have become the preferred construction method for many elevated highway projects in recent years. These beams, which have internal and external tendons, are increasingly popular because the internal tendons can improve the ductility of the beam, and the external tendons are convenient for maintenance. This study experimentally investigates the behaviors of segmental concrete box beams with hybrid tendons. Three scaled specimens with different ratios of the number of internal tendons to the number of external tendons were tested in detail. The experimental results showed that the ratio had a significant effect on the load-carrying capacity, ductility and failure mode of the beams. The opening of gaps between the segments could not be avoided, and the joint nearest to the applied load was determined to be the critical joint. The assumption that a plane section remained planar under bending was suitable for a crack joint produced by the load. The stress increment rule of the external tendons and internal tendons, as well as the variation of the plain bar strain, were determined. © 2012 Elsevier Ltd. Source

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