关键词: 灌注桩, SMW工法桩, 空间效应, 侧向位移, 土体沉降

Abstract: Spatial effects of strutted retaining structure caused by the higher stiffness at the corners lead to smaller ground movements near the corners and larger ground movements toward the middle of the excavation wall. In order to analyze the effects of influential factors such as the value of L/He (L is the distance in the longitudinal direction; He is the excavation depth) and excavation depth on spatial effects, a series of a field monitoring exercise including lateral displacement and soil settlement are conducted at two similar subway station deep foundation pits. Field monitored data indicate that the strengthening corner effect can lead to a significant reduction in wall deflection and the plane strain ratio(PSR). The plane strain ratio near the excavation corner is 0.50, 0.61, 0.72, respectively for the bored pile wall, soil mixing wall, diaphragm wall retaining structure. The corresponding value of L/He is 2.50, 6.00 and 4.00 when the plane strain ratio approaches to 1.00. Longitudinal maximum settlement increases first and holds steady with the increase of the value of L/He and the corner effect also increases with the increase of excavation depth. The corresponding value of L/He for the bored pile wall and soil mixing wall is 2.50 and 5.20, respectively, when the maximum settlement achieve stable value. The spatial effects of wall deflection are related to the surface settlement behind the retaining structure.

Key words: bored pile, soil-mixing wall, spatial effects, lateral displacement, soil settlement