Applied Mechanics and Materials Vols. 90-93

Abstract: The influence of shield tunneling on a nearby buried pipeline is studied by using the analytical method. Equations of displacements, rotations, bending moments, and shearing forces of a buried pipeline are set up respectively on the base of the theory of Winkler’s beam on elastic foundation. It shows the maximum settlement of the buried pipeline occurs in its middle span. Both the maximum bending moment and the shearing force of a buried pipeline take place at its two ends. The diffusion angle of the subgrade and the buried depth of the buried pipeline play an important role in the behavior of the buried pipeline.

Abstract: Ground settlement due to construction of underground crossing railway bed is an important issue. In this paper, the influence of the tunnels depths, the elasticity modulus, Poisson’s ratio, and internal friction angle of the sub grade soil property to the ground settlement during construction is simulated by the numerical simulation method. Some conclusions are drawn. Firstly, the tunnels depth doesn’t only influence the growth of the ground settlements, but also the shape of traverse settler. Secondly, the sub grade soil properties mainly affect the larger settlement; the shape of the settlement trough was relatively small.

Abstract: Abstract: Taking a High-speed railway tunnel as the background, This paper analyses not only the stress and displacement of surrounding rock , the plastic area distribution and size, but also the size and distribution of initial support internal force in two excavation schemes, based on the criterion of underground engineering structure design theory and rock elastic-plastic succumb Drucker-Prager, Under the guidance of New Austria Tunneling Method, this paper makes numerical simulation of soft rock tunnel excavation in large sections and initial support with the finite software ANSYS11.0. The stress and displacement of surrounding rock and the plastic area distribution and size under two excavation schemes are analyzed, the size and distribution of initial support internal force under two excavation schemes are also investigated .By comprehensive comparing advantages and disadvantages of two schemes, this paper makes some significant conclusions and gives reference for the similar tunnel design and construction.

Abstract: The development and evolution regularity of the interface shear stress for the inner bond section of geotechnical prestressed anchorage structure is directly related to the ultimate bearing capacity and its long-term durability. By adopting the similar model test and embedding the strain brick at each interfaces of inner bond section, the interface mechanical properties under step loading were systematically studied. Conclusions can be drawn as follows: the interface shear stress along the axial direction of rod is not evenly distributed, and the interface distribution shape at different radial distance from the rod axis also varies. With the gradual increase of external load, the shear stress peak point continues to move into the deep areas, and resulting in the occurrence of gradual damage mode. In the process, the peak value of shear stress also augment gradually. Along radial direction of the rod, the shear stress concentration phenomenon just distributes within a small radius around the rod body. Adopting the two stage linear function to describe the relationship of shear stress and shear displacement at contact surface is suitable.

Abstract: In seismic response analysis, total stress method is adopted mostly, but variation of the pore water pressure and the development process of the liquefaction are not considered in this method. Based on the dynamic analysis of two-dimensional effective stress proposed by Zhu-jiang Shen, combined with dynamic consolidation theory of Biot, the foundation liquefaction analysis of the diversion dike for nuclear power plant is performed by using effective stress dynamic analysis program, the liquefied range is given, as well as the permanent deformation. The obtained law can provide theoretical guidance for the similar project.

Abstract: The blasting method is regarded as a simple, convenient and economical method for constructing the underground structure, so it is advisable method for many underground structures to construct. But the investigation of the effect of the blasting dynamic load on the vicinal tunnel structure is rare, and the effect of blasting on the vicinal structures cannot be ignored either; sometimes, the effect will cause crack and even collapse in the tunnel liner and surrounding rock. So this paper presented the effect of blasting on the vicinal underground structure in differential cases using the finite element software Midas GTS. The investigation in this paper indicated which case will suffer the more severe effect caused by blast and let us know the vibration principle of the underground structure in differential case, and that will provide the knowledge about the vibration caused by blasting to the design and construction by numerical simulation; additionally, this paper has presented the reinforcement method about inserting the bolt into the surrounding rock to analyze how to resist the effect of the blast load. So from this analysis, it can be noted that the blasting method or the explosive energy will be chosen on the basis of different construction shape, and the reasonable location of the bolt will be adopted in order to reduce the effect of the dynamic on the vicinal tunnel structure.

Abstract: With the conduction of west development in China, the constructions of airports in the southwest mountainous areas are being carried out rapidly. Due to the various exteriors limitations, the embankment engineering in airports often exist some problems such as large height and slope ratio. So the stability of high embankment engineering is very essential to the construction and operation of airport. The cost of geo-grid material is very low and the construction is convenient. The embedding and occlusion of soil mass can be realized through its unique grid structure. The practical engineering shows that the stability of high embankment engineering can be solved through laying geo-grid in the filling soil. At the same time, FEM strength reduction can take the interaction between the components of geo-grid and soil into full consideration. As a strict mechanic method, FEM strength reduction can be reasonably and reliably adopted in the stability analysis, design and calculation of reinforced body with geo-grid.

Abstract: When it was leading prospecting in tunnel by TEM, the induced eddy current field would be produced on both side faces of a tunnel at the instant of disconnection of the excitation current. The receiver coil received the superposition of the eddy current field in the entire surrounding space, which was different from the superposition of eddy current field only with ground half-space. Using ANSYS computer program numerical simulated the propagation characteristic of transient electromagnetic fields in tunnel and compared the results on ground half-space with that in tunnel whole-space. The response curves were drawn by changing the depth of an abnormal body and the eigenfunction was obtained by fitting the curves. The results showed that the propagation in tunnel indicated “water wave effect” other than “smoking ring effect” on ground and the low conductivity body in tunnel changed the time-domain property of eddy current and displayed different curves.

Abstract: Abstract: the extent of roads damage and road safety are closely related. This article analyzes the advantages and disadvantages of Bayesian networks and it proposes that using matter-element Bayesian network model , the extent of road damage can be evaluated . The model is more scientific, more accurate and effectively ensures the unified state between subjective probability information with the objective state information . It provides accurate information for the investment decision of project maintenance .

Abstract: Taking Chaijiazhuang Tunnel of Lingnan Expressway as project background, the stability analysis of surrounding rock was performed based on the coupled fluid-solid theory. The distributions of stress field, displacement field and plastic zone of rock mass after excavation of tunnel were discussed considering coupled effect between flow and stress under the condition of different rock level and tunnel depth. Compared with the calculation results of not considering coupling effect, the maximum deformation, maximum principle stress and plastic zone size of wall rock were obviously increased when considering coupling effect, which showed a remarkable influence of coupled fluid-solid effect on the stability of tunnel surrounding rock. Some conclusions were drawn and may provide some guidance to the design and construction of tunnels in water-rich strata.