Applied Mechanics and Materials Vols. 90-93

Abstract: In accordance with characteristics of super-small-distance tunnels in Nanjing metro, the peak value distribution of vibration velocity for existing tunnel was investigated when cut-hole blasted under the conditions of different surrounding rock Grades, followed by dynamic response rule of super-small-distance tunnels blasting. In addition, monitoring emphasis should be placed on upper bench for right tunnel blasting. Therefore, controlled measures of the small-distance tunnels were obtained during construction. Not only is the result fit for the metro tunnel, but it can be as reference for similar engineering.

Abstract: The stability judgement of surrounding rock is one of the key jobs in tunnel engineering. Taking the Erlongdong fault bundle section of Guanjiao Tunnel as the background, the stability of surrounding rock during construction of soft rock tunnel was discussed preliminarily. Based on plastic strain catastrophe theory, and combining numerical results and in-situ data, the limit displacements for stability of surrounding rock were analyzed and obtained corresponding to the in-situ monitoring technology. It shows that the limit displacements obtained corresponds to engineering practice primarily. The plastic strain catastrophe theory under unloading condition provides new thought for ground stability of deep soft rock tunnel and can be good guidance and valuable reference to construction decision making and deformation managing of similar tunnels.

Abstract: The mechanism of the anchorage effect of the anchorage cable is very complicated. There are many factors which affect the anchoring effect. The loss of anchorage force concerns with the qualities of rock and soil masses, materials, anchor clamping, the construction technology and operation and management level and so on. Taking the Pre-stressed anchorage projects as examples, with the method of geological survey, experimental study, numerical simulation, theoretical analysis, the paper makes study on the loss of anchorage force caused by the qualities of hard rock, weak rock, and broken rock and soil masses. This template explains and demonstrates how to prepare your camera-ready paper for Trans Tech Publications. The best is to read these instructions and follow the outline of this text.

Abstract: The type B section of Hongqihegou station is cross section and its excavation section area is about 730 m2. This section is located in rail transit line 3 at the center of Chongqing. For this reason, the heavy traffic, large amount buildings and pipelines surrounding, super-shallow-buried depth and small cross-cover ratio (only 0.4) become the determinant factor in tunnel construction. By using a new method—the up-down sidewall drift method combined with first-wall-and-then-arch method, the Hongqihegou station was successfully completed. Through the analysis of the monitoring measurement data, the discipline of surrounding rock deformation during construction is revealed.

Abstract: Yixing Jingyi bridge was a cable stayed bridge with double layer arch tower—the main tower and the vice tower. When the main tower was lifting the pile in the post anchorage foundation only bear compression rather than tension. In this paper, the special design of pile cap was introduced, then the lower pile cap was analyzed by software ABAUQS. Finally, the displacement of the foundation was calculated by considering the effect of pile-soil-cap interaction.

Abstract: Deformation memory effect (DME) is one of the rock memory effects. One important application of the DME is to determine the in situ stress. The in situ stress measurement methods based on the DME are commercial and permit large number of measurements. Application of DME needs the reliable and effective identification methods to detect the DME. However, the existing identification methods are insufficient and not distinct. In this paper, a new method based on fractal dimension was proposed. It takes advantage of the increase of the irregularity of the stress-strain curve after the previous maximum stress attained. Numerical models for the sandstone and granite were developed based on the contact bond model in PFC^2D. Fractal dimension method was employed to detect the DME for two types of the rock. The results demonstrate that the fractal dimension method is effective and reliable in the identification of DME in rock.

Abstract: Discontinuous Deformation Analysis (DDA) method is used to analyze the stability, deformation and splitting failure of underground powerhouse excavation process with different lateral initial stress levels. Coefficient of lateral initial stress, reinforcement effect and joint structure pattern affecting on the surrounding rock are studied. The criterion for splitting failure in surrounding of underground is implemented to predict the depth of fracture area. It is shown that reinforcement with rockbolts will bring effects on rock surroundings in controlling deformation, stress distribution and stability.

Abstract: The field tests of interaction between structure and foundation were carried out in the present work which was quite different from the traditional divided method. The field experiments were done by using 20 pressure box and 3 inductance magnet rings in each survey hole. Through the tests data the mechanism of the foundation pressure and the distribution of layer settlement were studied. It is shown that there is an ultimate value as to the contribution of upper structure stiffness. The foundation pressure increases with the construction of building. But it will lead to a steady value from some floor to the top. And in the center of the foundation the foundation pressure is the biggest. As to the layer Settlement, the settlement decreases with the increasing of the depth. The Settlement and different settlement of natural foundation is the key to choose the type of their foundations.

Abstract: The contact stress between subgrade and subgrade plate was regarded as external force to subgrade. The circular subgrade is divided into rings, and supposing that the contact stress on rings is exerted on elastic subgrade sequentially. The potential energy functions of Bossinesq subgrade are derived by using superposition theorem and Bossinesq solution of elastic mechanics. The potential energy functions were given for the whole system of subgrade, subgrade plate and external forces. The displacement and stress state can be calculated with the principle of minimum potential energy through the potential energy function of the whole system.

Abstract: Based on the essential equations of transversely isotropic Mechanics in rectangular coordinates, the elastic controlling equations of transversely isotropic problems is transformed into a linear Constant coefficient homogeneous state equation by using double-Laplace transform and its differential properties. Then a general method is given for transversely isotropic elastic subgrade under arbitrary loading by means of the theory of the state space. The results of this paper are close to the calculation results of the finite element method and Bossinesq, as it showing this method is feasible. This paper gives a new method for transversely isotropic elastic subgrade.