Ground movements induced from excavations is a major cause of ... values of lateral deformations and straining actions for sheet pile wall and settlement in strip.
EEFECT OF SHEET PILE WALL SUPPORTED EXCAVATION ON ADJACENT STRIP FOUNDATION Yousry M. Mowafy 1, Ahmed M. El-Tuhami 2, Samir A. Gad 3, and Ahmed A. Mohamed 4. ABSTRACT Ground movements induced from excavations is a major cause of deformation and damage to the adjacent buildings and utilities. This problem is investigated experimentally and numerically in the present study. Two parameters were studied, the first is the foundation depth and the second is the building distance from the excavation. Nodal displacements and elements straining actions were determined and analyzed. Finally, a series of finite element analysis was performed on a prototype dimensions and a comparison between the laboratory model tests and the finite element analysis was presented. It is found that the value of (lateral deformation /H) is 0.01 in cantilever sheet pile wall and the relative density is the important factor in decreasing values of lateral deformations and straining actions for sheet pile wall and settlement in strip footing. Keywords: Excavation, Relative distance, Lateral deformation, Relative depth. 1. Introduction Deformations of the excavation support system adjacent ground are influenced by a number of factors including stiffness of the excavation support system, the installation procedures of the system, the soil conditions, the excavation procedures, the type of building, the distance of the building from the excavation, the orientation of the building with respect to the excavation, and the size of the building with respect to the excavation-related deformations. To confirm this speculation, model testing of braced excavations was conducted to examine the effects of varying the building’s depth of foundation and the building’s distance from the excavation face. Boscardin and Cording [1989] and Boone [1996] have both recognized that excavation-related limiting criteria is a function of building type and orientation with respect to the excavation, type of support system, excavation techniques, and soil conditions. Kishnani and Borja (1993) found that wall pressures and deformation increase with decrease in adhesion between sheet pile wall and soil. Milligan (1983) studied analytically the deformations behind flexible retaining walls anchored at the top and performed a number of model tests with dense sand to study the deformations. Hashash and Wittle [1996] investigated the effects of wall embedment depth, support conditions, and stress history profile on the undrained deformations around a braced diaphragm wall in a deep clay deposit, using a series of numerical experimentsnonlinear finite element analyses. The results are presented in prototype design charts for estimating ground movements as functions of the excavation depth and the support conditions, and incorporate the effects of wall length on base stability. Seok et al. [2001] observed that braced excavations inevitably result in deformation of the adjacent ground and settlement of adjacent buildings behind the wall. Building settlement is believed to exceed the amount of associated ground settlement because of the additional settlement under building weight. This is due to decrease in stiffness of the foundation soil that is caused by lateral movement of the 1) Professor of Soil Mechanics and Foundations, Civil Eng. Dept., AL-Azhar University, Cairo, Egypt. 2) Associate Professor of Soil Mechanics and Foundations, Civil Eng. Dept. Beni-Suef University, Beni-Suef, Egypt. 3) Associate Professor of Soil Mechanics and Foundations, Civil Eng. Dept. AL-Azhar University, Cairo, Egypt. 4) Teaching Assistant, Civil Eng. Dept., Alazhar University, Qena, Egypt.
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excavation face. To quantify the amount of building settlement, model testing was conducted to determine the magnitude of the additional settlement due to the structure and the effect of varying the building’s depth in the ground and of its distance away from the excavation wall. Son et.al. [2005] observed that the bearing walls oriented in a direction perpendicular to an excavation wall tend to become distorted with shear strain and lateral strain at the foundation level. When ground movement initially impinges on the front of the building, the building is primarily subjected to shear distortion and lateral strain at the base. Peck (1969), Goldberg et al. (1976), and Clough and O’Rourke (1990) suggested that in deep excavations in stiff clays, residual soils, and sands, the maximum lateral wall movement, δhmax, is less than 0.5% of the excavation depth, H . Figure (2.10) shows data collected by Clough and O’Rourke (1990) on lateral wall movement for different types of retained walls. In this figure the average normalized lateral wall movement, δhmax ∕ H ≈0.2%, and cases with δhmax ∕ H ≈0.5%, are reported to represent poor construction work. Moormann (2004) concluded that ground conditions were one of the identified most influential parameters. The maximum lateral and vertical movements due to deep excavation in cohesive soils of very soft to soft consistency, with undrained shear strength cu
