Applied Mechanics and Materials Vols. 170-173

Abstract: Compared with current finite element analysis and monitoring techniques, prediction model of deformation of complicate soil nailing bracing for foundation pit based on grey system theory is a short-time method. It exactly exhibits the “less data” characteristics of grey system theory and is satisfied with the urgent requirement of mastering deformation of foundation pit in a short period. In Addition, through theoretical analysis and engineering practical example, the method is proved feasible.

Abstract: The purpose of this paper is to present a numerical model of coupled heat, moisture transfer and their effects on the porosity changes of soil during the freezing process. Coupling among heat, moisture, and mechanical deformations is solved based on finite element method. The equilibrium equations of freezing process are investigated based on segregation theory. The numerical model is applied to a 2D problem of a laboratory frost heave test. Numerical simulation reveals the porosity characters during the freezing process. The frost depths and deformations also the porosity in consideration of the orthotropic properties of frozen soil is discussed.

Abstract: Emergency logistics is not a normal logistics, the objective of its supply chain is to maximize time efficiency and minimize disaster losses. It is an important protection mechanism of emergency rescue system, after the emergency incident ,the reliable operation of the logistics supply chain is the basis and key of emergency rescue. This paper introduces the characteristics of emergency logistics and reliability theory, establishes the reliability model and its evaluation system of emergency logistics supply chain, and explores the optimization problem of the reliability, the system logical structure and logistics cost.

Abstract: According to the geology condition of 1028 face in Suntuan Coal Mine of Huaibei Mining Group, evolution law of stress and displacement of water-resisting floor along with working face ad-vancement was studied. The results show that the stress and the displacement of the floor change dynamically , the displacement in the front and back of working face ,and the difference of displacement result from stress concentration before mining ,relief pressure after mining , superpo-sition effect of additive stress caused by the additional stress in stress recovery . The measures to re-duce the coal floor damage were proposed.

Abstract: Through project example, analysis of the multi-type-pile composite foundation (lime pile plus CFG pile) in the practical application of liquefied foundation of high-rise building, especially using the ZFZ construction technology which forwards formed a hole and reverses packed into a compaction pile by a long spiral drilling machine to eliminate liquefaction of foundation soil and improve the bearing capacity of foundation is very notable, in addition, it also produces good economic and social benefits, so it has great value of promotion and use.

Abstract: Based on formulas of elastic mechanics, the axisymmetric problem applied to an elastic footing is analyzed. Using Hankel transform and finite difference method, the arbitrary points’ displacement and stress solutions of the axisymmetric elastic footing problem is obtained. Compared with recursive substitution method and transfer matrix method, this method is simple because it avoids complex formulas and exponential function calculation. The half space model is more flexible to simulate an actual footing. The numerical solutions are compared with Boussinesq’s Equation and results show that finite difference method is applicable to solve axisymmetric elastic footing problem. But in the application of finite difference method, there are a few factors that could cause calculation errors. Effective measures are needed to obtain exact solutions.

Abstract: In order to predict the stability of surrounding rock mass in geotechnical engineering, it is important to study the post-failure deformation property and residual strength of rock mass. Based on evolutional behavior of strength parameters, aiming at generalized Hoek-Brown strength criterion, selecting major principal strain as strain softening parameter, this paper presents the method of solving post-failure stress-strain curve . In numerical case, the effect of evolutional law of strength parameters ， and to deformation and residual strength is discussed and we can draw the following conclusions: the greater the residual values of ， are and the smaller the residual value of is, the post-failure strain softening curve falls more gently and the greater the residual strength is.

Abstract: It is difficult to investigate the geological condition entirely, and the physical and mechanical indexes are inaccurate. All these uncertain factors make both the theoretical and numerical calculation results of foundation settlement different with actual situation. Based on summarizing research results about settlement prediction methods for soft subgrade, actual example analysis is provided with using the measured settlement data to predict the settlement of the soft ground treated by the preloading drainage consolidation method after construction. The analysis method of soft ground settlement during secondary consolidation stage is discussed, and a new calculation model for secondary consolidation settlement is proposed. Considering the different characteristics of the settlement curves during primary and secondary consolidation stages, an improved method is provided to calculate settlement by piecewise curve fitting, and the rationality of the method is verified by analyzing the monitoring data of typical settlement plate in Shenzhen Western Corridor Project. To sum up, in actual engineering practice the settlement developing trends and final settlement can be well predicted with using part of the measured settlement data obtained. Comparing to other methods, settlement prediction with using actual measured data is relatively accurate and reliable. It does not need geological data and the calculation process is simple for engineering and technical personnel to grasp and accept.

Abstract: For difference of elevation of transmission line in mountain areas, special considerations are needed for foundation design and construction.Take double-loop wire of 2×400 and mixed voltage four-loop wire of 2×630 iron tower as analysis examples, material quantity and economy index of different types of foundation in mountain areas are analysed in this paper so as to provide inference information for electrical construction.

Abstract: It was a common method to simulate the complicated rock mass’ exterior profile, interior structure and corresponding project structure through the graphic platform of 3D digital modeling in modern geotechnical engineering. Based on such a modeling, this paper introduced a graphic method of hexahedral grid dissection in numerical calculation, which regarded the rock mass modeling cut by faults, cracks and buildings as a compound entity of hexahedral entities, and on every adjacent interface of any two hexahedral entities there would be the same number of grids of the same size and they were of the same topological relations. With overrun mapping method to traverse calculate all the single grids of all hexahedral prisms, a grid calculating system of the complicated rock mass would be formed. After applying such a method to several major projects, we are very satisfied to find that with such a method the rock mass is divided reasonably and the calculation accuracy meets the requirements.