Advanced Materials Research Vols. 446-449

Abstract: The bending stiffness of segmental joints is the key factor which affects the mechanical characteristics of shield tunnel. In this paper, full-scale tests and numerical analysis were carried out to study the bending stiffness, joint opening variation and failure characteristics of segmental joint structure for under-river shield tunnel. The results showed the bending stiffness and joint opening behaving non-linear significantly. And the concrete cracking and bolt breaking were detected in the tests.

Abstract: The tunnel - subgrade - adjacent buildings interaction model was established by ANSYS to simulate the soil displacement by Running Subway to adjacent buildings. According to D'Alembert principle, we got the dynamic load produced by train acceleration. Multi-point load was applied to simulate the movement of train. Based on ANSYS simulation results, the surrounding soil displacement of the tunnel was analyzed when in different train speed. On the other hand, the soil displacement in different depths is analyzed when in the same train speed.

Abstract: This work used FDS to simulate tunnel fires occur in a semi-circular longitudinally ventilated tunnel. By varying the parameters such as the tunnel gradient, the fire size, and the ventilation velocity, their influence on the backlayering effect and downstream propagation rate can be recognized. Under weak ventilation, the backlayering effect either advances or vanishes depending on the slope of the tunnel. Under stronger ventilation, the backlayering effect would break up. The temperature distributions may become less and less dependent on the tunnel gradient when the ventilation velocity is increased. Although the hot gases and smoke in uphill tunnels propagate faster than those in downhill tunnels, their difference reduces with ventilation velocity.

Abstract: Abstract: Owing to several construction procedures of bidirectional 6 lane multi-arch tunnel, with the characteristics of large dig span and flat cross section, the wall rock and support structure of which will be repeatedly disturbed by multiple excavations, so their mechanical and deformational features are remarkably complicated. Combined with the design and construction practice of Sha Tangkeng bidirectional 6 lane multi-arch tunnel of Guang-He highway, taking the V grade surrounding rock for case, with the help of 3-dimension finite element numerical simulation method and 3-dimension physical similar model test, the paper studied the entire dynamic construction process of bidirectional 6 lane multi-arch tunnel, analyzed the chang characteristics of displacement and stress of wall rock and stress of supporting structure, and revealed the time-space effect laws of construction of bidirectional 6 lane multi-arch tunnel.

Abstract: This paper， based on the distortion and failure character of soft rock Roadway in Bide coal mine, analyzed deformation and failure mechanisms of soft rock roadway that all are effected by factors of ground stress, lithology, mining influence, unreasonable support parameters and water. The new supporting scheme and parameters optimization of roadway were presented by means of ground stress measurement, mechanics parameters determination of roof and floor rock, monitoring of anchor-hold and result of surrounding rock classification. Then, through numerical simulation, this paper analyzed how the new supporting scheme could control the deformation of surrounding rock effectively, reduce tress in periphery area of surrounding rock, and decrease the stress concentration region of roadway, and prevent the base angle rock mass from macro shear slipping. The field examination results showed that the new supporting scheme was feasible, which can ensure the stability of roadway, with no consequences like roof falls, rib spalling and floor heave.The research results can be used as reference to design supporting structure in high ground stress soft rock roadway .

Abstract: The safety management of tower cranes is a systematic engineering. Focused on the complexity and uncertainty of the safety evaluation of tower cranes, D-S evidence theory is applied to evaluate the the safety conditions of tower cranes in service, the safety risk assessment index system of tower cranes is built and the specific and improved algorithm of the evidence theory is given. through example calculation, this method is proved is feasible, effective and applicable in the safety evaluation of tower cranes.

Abstract: The probability distribution of buoyancy amplitude of vortex-induced vibration for a submerged floating tunnel with single span under steady flow is studied by means of Monte-Calor method in this paper. The probability response of bending moment and displacement in the central span of submersed floating tunnel, including shear response at its buttress are also analyzed. Meanwhile, the reliability of a submerged floating tunnel with single span is also calculated in terms of the structural limit state equation under vortex-induced vibration.

Abstract: The stiffening girder of suspension bridge is usually erected by a deck unit erection gantry because of low cost and short construction period. Mechanical behaviors of deck unit erection gantry for suspension bridge were investigated with an example for Aizhai Bridge located in Hunan province. The beam elements and shell elements were used for the analyses of steel truss and moveable supports of the gantry respectively.

Abstract: Based on the Shuangbei tunnel, this paper studied influences on the deformation and stress of surrounding rock, regarding different Karst sizes and locations in such a neighborhood tunnel. The study indicates that variations of size and distance of the karst have prominent influence on the vertical displacements of vault and right side-wall in the tunnel near the karst, but have no influence on the horizontal displacement; while variation of karst size has prominent influence not only on the horizontal displacement, but also on the vertical displacement at the bottom of the tunnel far away from the karst; variations of size and distance of the karst have the prominent influence on the vault stress of the two tunnels. The results offer the reference to the tunnel construction and the selection of support type.

Abstract: Considering the effect on surrounding rock exerted by TBM construction and its corresponding support measures are quite different from those of drilling and blasting construction, this study attempts to investigate the disturbance of TBM construction and its countermeasures. The investigation specifies the size of the drop pieces, position and cause and provides support measures for different stability condition of surrounding rock.