Applied Mechanics and Materials Vols. 580-583

Abstract: The mechanics characteristics of the rock are mainly subjected by the joint and the fractures of the rock mass. For the joint, the surface morphology is especially the dominant influence factor. In order to describe the nature physics of rock surface, the surface morphology embarked on a fractured granite rock is described. And use the fractal dimension to calculate the volume of covering rock fracture surface, the relationship between fractal dimension and physical characteristics of rock surface.

Abstract: Deformation process of slope has been controlled by a variety of factors due to the unique geological, hydrological and meteorological conditions. And southwest mountain areas of China has been become high incidence areas of slope diseases during highway construction and operation. According to Wendu Road K55+590 ~ K55+670 left slope engineering geological environment, the deformation process and mechanism analysis, The key factor of the slope deforming destruction is proposed. the appropriate engineering treatments and the construction control measures are also proposed based on analysis.

Abstract: This paper presents an improved anisotropic bounding surface model which is based on Wheeler’s elastoplastic model (S-CLAY1). The developed model is programmed in ABAQUS software by writing UMAT subroutine, which is integrated in Return Mapping Algorithm. The parameters sensitivity analysis is implemented on plastic modulus. The study shows that the developed anisotropic bounding surface model is capable of describing the dynamic properties of soft clay.

Abstract: Long-span and bifurcation tunnel engineering is not very common in underground engineering field. It is difficult to construct this complicated structure because of the numerous influencing factors. In order to find out the optimum construction method for long-span and bifurcation tunnel to guarantee construction security and stabilization of this project, six construction methods were compared and analyzed by using numerical simulation. The results show that: (1) The excavation of confluence segment and small interval tunnel can affect each other but the confluence segment is the crucial part of the whole project. (2) The vertical brace determines surrounding rock and preliminary support stabilization in confluence segment. (3) The central concrete between main tunnel and ramp tunnel is the key point to guarantee the construction security and stabilization of small interval tunnel. The above results certainly contribute to research and develop new types of construction methods for long-span and bifurcation tunnel engineering.

Abstract: In order to survey the time-varying effect on shield tunnel lining structure, rigidity reduce in the Homogeneous Ring Design Theory is introduced. There are three methods to evaluate the rigidity reduction caused by the aging effect. The first is the bending rigidity analysis method, which considers that the bending rigidity changes with the time-dependent stress and strain. The second is the method named the equivalent moment of inertia; the last is aging coefficient method. With the Homogeneous Ring Design Theory, the internal forces and displacement of the shield tunnel segment lining can be calculated. Based on the preliminary results, using the 1^st method, the reduced rigidity and the long-time displacement at different instants of time can be calculated. It is found that the concrete shrinkage and creep effect can’t be ignored in the segment design. The survey is beneficial to monitor the deformation of tunnel lining, and the maintenance of the segments. It will make the tunnel work steadily and safely during the using period.

Abstract: In order to evaluate the health condition of the tunnel in South China and give advices on reinforcement and maintenance scheme, a post-earthquake health diagnosis method is presented. After a comprehensive investigation on failure modes of tunnel, a four-level ranking method and a index system for post-earthquake health diagnosis of highway tunnel are proposed. Besides, analytical hierarchy process (AHP) is introduced into for determining the post-earthquake health diagnosis mode. Case study manifests the validity of the proposed method, which can provide valuable guide to the post-earthquake health diagnosis and relief work.

Abstract: To research the deformation regularity of large section loess tunnel in construction procession with different construction methods, 3D Numerical Simulation is applied and the large-section loess tunnel of highway is taken as an example. Comparing deformation regularity of surrounding rock in three types of construction method conditions, the research results show that:The CRD method takes precedence in the condition of the convergence of surrounding rock is large. The both sides heading method takes precedence in the condition of ground surface settlement is large.

Abstract: In the background of a foundation pit excavation project on Yanan Road in Hangzhou City, this study simulated the excavation of foundation pit above an underground tunnel using 3D MIDAS/GTS software. The combined action of foundation pit, ground and tunnel were considered. The influence of foundation pit excavation on the deformation of underlain shield tunnel was evaluated and simulations were carried out on the effectiveness of different strengthening and control approaches. Results from the research showed that during the stages of piling and ground strengthening, settlement occurred at the tunnel; with the excavation of foundation pit, uplift deformation at the bottom of the foundation pit and the tunnel increased; with stricter strengthening and control techniques employed, the magnitude of uplift at the tunnel and bottom of the foundation pit reduced, suggesting that various control procedures were effective to some extent.

Abstract: According to Pingyang tunnel karst complex groundwater environment ,This paper carried out thorough theoretical analysis and field observation from Pingyang tunnel stratum rock properties, engineering geology, hydrogeology, the surrounding patch, runoff and drainage and the changes of surface water environment, as well as tunnel excavating. The complex formation mechanism has given in the Pingyang tunnel karst water . Some effective references had put forward for the engineering treatment, provided some valuable references for other similar underground engineering construction.

Abstract: Confronting with the difficulties of the construction metro station in the Northeast of China, a new idea of shield method combined prefabricated method is put forward. In the paper the research status of the underground engineering precast assembly technology was analyzed and classified firstly. The method of single round interval shield combined with open-cut (or covered excavation) prefabricated sections and on the basis of shield tunnel to build single arch station is especially worth studying and promotion. Then the key prefabricate theory needing to deal with such as how to calculating the spring stiffness and so forth of the calculating model. The key technology such as joint formation, waterproof and the other of shield method combined with prefabricated method was discussed.