A simplified and effective analysis is introduced to monitor dynamic behaviors of the pile foundations. The method based on wave equation of the piles can simulate the effects of the cap and the interactive piles as well as other design parameters. The applicable subjects may include the pile responses due to the superstructure loads, the foundation capacity and the seismic design concerns. Corresponding results are found similar to the FEM ones, however it is more efficient for the engineers in making the optimized design solution.
Slope stability is traditionally analyzed with limit equilibrium method. The factor of safety is used as a criterion for assessing safety of slopes. However, stress and deformation in the soil mass of slopes would not be possibly obtained with limit equilibrium analysis. Methodology along with the finite element procedure for analyzing slope stability problems in stormy condition is studied in this paper. Strength reduction method is used for determining factor of safety of slopes in the finite element procedure. Factors of safety analyzed with finite element method are close to those analyzed with limit equilibrium method for various slope angles. Also, factors of safety analyzed with finite element method are 10%~15% greater than those analyzed with limit equilibrium method for reasonable cohesion and friction angle conditions. A wetting zone in the slope is developed in the stormy condition. Softening of soils has a significant influence on loss of cohesion of soils. Procedures of slope stability analysis in stormy condition for three ground water levels are proposed in this paper. Failure of slopes in stormy condition may develop in the sallow depth and result in a sudden drop in factor of safety if loss of cohesion of the soil is significant. Finally, a case history of a landslip induced by chances in the environmental conditions is analyzed with the finite element procedure. The computed results of slope deformation with time effect are compared with the measured results. The computed results compare well with measured results for short period of time. However, discrepancy between measured and computed results becomes significant for long period of time. Failure in predicting precise slip surfaces and inhomogeneous geologic condition may be the primary reasons blamed for it.
The analysis of dynamic soil-structure interaction is quite complicated and difficult to be understood by engineers. In this paper, a simplified model is used to describe the method of soil-structure interaction analysis and its effects on the dynamic response of a structure. The model adopted is a single-degree-of-freedom structure resting on a uniform elastic half-space. The fundamental frequency of the combined soil-structure system is determined not only by the structure itself, but also by the side-sway and rocking impedance of the foundation soils. It is different from the structural natural frequency calculated based on the rigid-base model as conventionally used in the engineering design. It is proposed to use the frequency ratio as an empirical index to estimate the significance of soil-structure interaction effects. In the paper, the case of Hualien Large-Scale Seismic Test is investigated and the results of analysis are compared with measured data from field test and earthquake response. Results clearly show that the significant influences of soil-structure interaction on the dynamic response of the structure.
This paper discusses the back-analysis result of two preliminary pile load tests, in the axial and lateral directions, of an ongoing major elevated structure project. The purpose of the evaluation was to understand the influence of soil parameters upon analysis results, and subsequently to determine the soil parameters yielding reasonable stress-strain agreement between analytical and monitoring results. This paper provides a practical approach for evaluating pile load test results and obtaining foundation design parameters.
The two testing piles were mainly located in alluvial soils, underlying by sandstone and mudstone. For evaluation purpose, the p-y curve method and the t-z curve method were applied to back-analyze the lateral and vertical deformation behaviors of the testing piles.
The back-analysis results provided better understanding of pile behaviors, and more reliable parameters were determined for foundation design.
The New Austrian Tunnel Method is famously and usually used method in tunnel excavation. nevertheless, it is always lack of the evident methods for analysis and design. Therefore, the objectives of this paper are the introduction of the Convergence-Confinement Method, the establishment of steps of analysis and calculation by means of the regression analysis obtained from the measurements, and the prediction of interaction between rock mass and support system in tunnel excavation. The content of this paper includes the analysis and illustration of calculation steps in supposed case of tunneling, the application of analytical calculation to the railway tunnel and the road tunnel. According to the analytical calculations obtained, the displacements of pre-stage and of unsupported distance, the modulus of elasticity of rock mass, the pressure of support system, and the longitudinal deformation curve are particularly observed.