Applied Mechanics and Materials Vols. 275-277

Abstract: The paper studied a side slope engineering of highway in K29+450~K29+900 sections by making an on-site survey of landform and geological features of the side slope. By combining drilling, high-density electrical method and numerical simulation method, the depth and range of the sliding surface were determined. The stability of the side slope after an excavation in a normal and a rainfall conditions was analyzed using numerical simulation method, and simulation results show that in the normal condition the safety factor of the side slope is 1.12, and it is 1.05 in the rainfall condition; the distribution of plastic zones is wide, especially in the rainfall condition, the side slope has a large deformation and is in an unstable state. When a program of side slope reinforcement is chosen, the impact under rainfall condition should be considered in order to ensure long-term stability of side slope.

Abstract: Seismic response of a large span cable based bridge with inconsistent inputs is analyzed in this paper. The bridge model is built by the function of finite element software ANSYS. The free vibration characteristics of the bridge are analyzed by Lanczos Vector Iterative method. The first and the twentieth free vibration frequencies are 0.06808 Hz and 0.54392 Hz respectively. A set of motions of consistent, traveling wave and synthesized (inconsistent) are adopted as inputs at the two supports. The lengthwise, lateral and vertical displacements at the span center and quarter span of the main girder, at the tops of the supporting towers, and the internal forces in the girder and at the base of the towers are calculated. The result shows obviously the necessity to take into account inconsistent input in seismic response analysis of large span bridge.

Abstract: To study the dynamic response rule of the western slope in Buzhaoba under explosion, a vibrational wave was imposed on the slope. The FLAC3D program was utilized to simulate the rule. The distribution of stress field and the response of velocity were analyzed after blasting. The simulation result shows that the compressive stress increase step by step with the increase of the depth of slope, and as the elevation increases, the particle velocity appears an amplification effect, and the slope is mainly affected by the self-weight stress, and the blasting has little effect on the slope.

Abstract: Ultra-soft soil improvement projects are new trend in present China because of the limitation of construction period. Technical problems occur when traditional vacuum preloading method is applied for ultra-soft soil. This paper firstly gave an analysis of the main technical problems which include construction channel problems for building materials and workers, portion division problems of project area, installation problems of prefabricated vertical drains and formation problems of horizontal drainage cushion. Then solutions for these problems were presented. Based on the solutions and traditional vacuum preloading method, a new method for ultra-soft soil improving was put forward. A typical application of this new method was give at the end of this paper.

Abstract: In seismic analysis of large span bridge, inconsistent ground motions in three directions, lengthwise, lateral and vertical are required to input at the base of each of the two main girder piers. In order to adopt synthesized motion field for the inputs, a simple way to prepare the vertical motion is introduced for improvisation at this moment in this paper, since the synthesis in general consists of two parts, the low frequency ground motion calculated by a numerical method, like FEM, and the high frequency motion synthesized by random approach, and the result of the former is in three dimensional, while that of the latter has just horizontal component. The vertical acceleration time histories proposed in the paper show the way is available.

Abstract: Result of seismic response analysis of a large span cable based bridge with inconsistent inputs is presented in a conjugated paper and is further deal with in this paper. The results from synthesized motions for the same earthquake source and same distance to the rupture show a large difference. They are compared with characteristics of the inputs in this paper. The effect of the motion amplitudes and the coherency between the input motions at the two ends of the main girder on the maximum response displacements and internal forces are pointed out.

Abstract: As a new ground treatment technology, the bag-grouting-pile composite foundation is used in railway soft soil reinforcement. In this paper, the application effect of bag-grouting-pile in coastal soft foundation treatment was studied in this experimental research; the deep settlement and the deep horizontal displacement of embankment edge in bag-grouting-pile composite foundation are tested in the research. The results of research show that the bag-grouting-pile composite foundation is a cost-effective ground treatment technology using in coastal soft foundation treatment.

Abstract: Residual displacement is an important measure of post-earthquake functionality of engineering structures. Empirical equations for prediction of residual displacement of SDOF system from its peak inelastic displacement were proposed through a comprehensive statistical analysis. An inelastic seismic analysis model including the P-Δ effect was employed to assess the residual and peak inelastic displacements of SDOF system under horizontal and vertical excitations. The correlation and empirical equations between residual and peak inelastic displacements were discussed based on 69 selected earthquake records. Results show that the correlation between residual and peak inelastic displacements are of high correlation, and the mean of residual-to-peak displacement ratio increases with the increase of period of vibration or stability factor. Furthermore, the coefficient of variation of residual-to-peak displacement ratio decreases with the increase of the period of vibration dramatically for rigid systems and is generally independent of the stability factor and the normalized yield strength.

Abstract: Probabilistic residual displacement analysis plays an important role in determination of technical or economical feasibility of repairing the damaged emgineering structures after an earthquake. Probabilistic characteristics of residual displacements of SDOF systems were quantificationally investigated in this study through a comprehensive statistical analysis. The influences of the P-Δ effect, period of vibration, normalized yield strength and post-yield stiffness ratio on probabilistic characteristics of residual displacements were investigated based on 69 selected earthquake records. In particular, the probability models for the normalized residual displacements were proposed and tested. Results show that the P-Δ effect and post-yield stiffness ratio have significant impacts on the residual displacements; the period of vibration also obviously influences the residual displacements for rigid systems; the residual displacement can be described as the Lognormal distribution variable.

Abstract: Based on finite element analysis software ANSYS, slope stability analysis is carried out by Elastic limiting equilibrium method proposed in this paper. A series of sliding surface of the slope can be assumed firstly, and then stress field along the sliding surface is analyzed as the slope is in elastic state. The normal and tangential stresses along each sliding surface can be obtained, respectively. Then the safety factor for each slip surface can be calculated, the slip surface which the safety factor is smallest is the most dangerous sliding surface. This method is different from the previous limit equilibrium method. For the previous limit equilibrium method, the normal and tangential stresses along the sliding surface are calculated based on many assumptions. While, the limit equilibrium method proposed in this paper has fewer assumptions and clear physical meaning.