Impact of the Unsupported Excavation on the Boundary of the Active Zone in medium, stiff, and very stiff Clay

Soil excavation in clayey soils beside existing inhabited and/or historical buildings represents a challenge to the geotechnical engineers in many circumstances. The presence of ground water above the excavation level makes the excavation more costly. Many excavation support systems are available including; soldier pile walls, sheet pile walls, secant piles, tangent piles, diaphragm walls, etc. These techniques may be cost-effectively for large and important projects while small projects represent the majority. The restriction of the lateral movement of the soil underneath the existing adjacent building represents the primary objective for any excavation support system. The xcavation without support system may be achieved by executing both the excavation and foundation in stages to reduce the cost. This paper focuses on the investigation of the boundary of the active zone of medium, stiff, and very stiff clay soils in the vicinity of existing facilities by numerical simulation. The horizontal distance of the boundary (H), depends on many parameters including the vertical pressure from the adjacent structure (q), the clay shear strength (c), the excavation depth (de), and ground water depth (dw). For each clay type a design chart was created representing the relationship between the lateral safe distance of the active zone and the excavation depth for a given surcharge pressure.

کلیدواژه ها:

unsupported excavation ، lateral displacement ، supporting systems