| Summary: | 碩士 === 國立屏東科技大學 === 土木工程技術研究所 === 86 === Current lateral earth pressure diagrams in the design were generally based upon the measurements obtained from sheet pile wall and soldier beam-wood lagging retaining wall systems. Those retaining systems are relatively less rigid compared with the current widely used reinforced concrete slurry wall system. However, the influence of wall rigidity on the behavior of retaining wall system is unknown. Therefore,the objective of the study is to investigate the stability and lateral earth pressure distribution of
reinforced concrete slurry wall system by using the finite element analysis.
The behavior of an interface element was investigated in order to provide sufficient information to simulate the relative displacement at the contact surface between soil and retaining wall system. The stability of slurry wall system was also investigated by using current design methods for better understanding of the physical meaning of the results obtained from the finite element analysis. A series of direct shear tests and finite element analyses were performed to investigate the frictional behavior among three types of
soils and four different kinds of retaining wall materials. The results of the study shown that the frictional behavior at soil-retaining wall system can be simulated by using an exponential function that consists of two control variables, which are shear modulus (C exp) and displacement modulus (l). For the conditions of analyzed, the shear moduli varied from 0.415 to 0.425 and the displacement moduli varied from 0.002 to 0.008, respectively. Generally, shear modulus of 0.42 and displacement modulus of 0.002 are recommended to be used in the finite element analysis. The embedment analysis for deep excavation of slurry retaining wall system was performed by using NACFAC procedure and the finite element analysis. The results of the analysis shown that the embedment of 0.3 - 0.4 times of excavation depth is sufficient by
using NACFAC procedure. However, the results obtained from the finite element analysis indicated that the embedment of 0.8 - 1.0 times of excavation depth is required to maintain the stability of the deep excavation.In the NACFAC procedure of embedment analysis, the stability of the retaining wall system is based upon the ratio of the resistance moment over the driving moment at the bottom supporting hinge. The entire flexure strength of the retaining wall system is included in resistance moment in the analysis. However, the developed resistance moment of reinforced concrete slurry wall system is depend upon the deflection of the retaining wall. Therefore, the current NACFAC procedure is required some modification in t he embedment analysis for reinforced concrete slurry system. A comparison among various lateral earth pressure diagrams was made in the study. The results of the analysis shown that the variation of the total strut forces calculated by different diagrams is very minimum. However, it is not recommended to use Tschbotariff method to
estimate lateral strut forces of retaining wall system in dense sand.
According to the results of finite element analysis, the rigidity of retaining wall system has significant effect on the lateral earth pressure distribution of retaining wall system. If the rigidity of the retaining wall is only 1% of
reinforced concrete stiffness, the lateral earth pressure distribution is quite similar to that observed from sheet pile wall system. However, the lateral earth pressure diagram of reinforced concrete retaining wall system is quite similar to Rankine active earth pressure diag ram. Therefore, it is
recommend that the apparent lateral earth pressure diagram based upon the observation from sheet pile wall system should not to be used in the design of slurry wall system.
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