| Summary: | 碩士 === 國立臺灣科技大學 === 營建工程系 === 98 === In an urban region, the design of a deep excavation project commonly involves the existing of adjacent buildings. Former studies have indicated that the earth pressure induced by the finite soil body is smaller than that caused by infinite soil mass. Therefore, this study intends to analyze the earth pressure characteristics and discuss thoroughly its application in the condition of finite soil body. Both cohesive and cohesionless soils are considered in this study. By adopting the theory of limit equilibrium method, this study first develops the relationship between the earth pressure and L/H relationship (in which L is the free length of soil mass and H is the excavation depth). This development is then numerically verified by finite element method. It is observed that to be conservative, the influence of the wall friction need not be taken into account. Under this circumstance, for cohesionless soil with friction angle ? < 350 and ratio L/H < 0.5, the earth pressures vary significantly at various L/H values and should be considered. On the other hand, when the ratio L/H ?d 0.7 the earth pressure coefficient converges to that of infinite soil mass. For cohesionless soil, the lateral earth pressure of finite soil body can be determined by the normalized reduction factor Rd. For cohesive soil, the lateral earth pressure can be calculated using the equivalent coefficient of lateral earth pressure of finite soil mass. This study presents the analyses of two case histories to verify these foregoing findings. The results exhibit good agreement between the calculated and the measured values. The error is about 10to 20%. Thus, the methods developed in this study can be adopted for the design of deep excavation.
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