Performances and Working Mechanisms of Inclined Retaining Structures for Deep Excavations

Abstract

Because of the limits of struts, braceless retaining structures (BRS) have become a preferred option in deep excavation engineering. A type of BRS, that is, inclined retaining system, has been successfully applied in several projects. However, its performance and working mechanism have not been systematically studied. A case study and finite element results in this study show that inclined piles (IP) are more effective than vertical piles (VP), while composite inclined retaining structures (CIRSs) are more effective than IP in terms of deflection and bending moment reduction. The deformation-control mechanism of IP mainly comes from the decrease in the active earth pressure. For CIRSs, the working mechanism is governed by several combined effects, that is, the rigid frame effect, inclined strut effect, earth berm effect, and gravity wall effect. For instance, in composite vertical and inward-inclined piles (VIIP), inclined piles function as struts for the vertical piles in this rigid frame system and frictional force between the soil and the inclined piles significantly influences its retaining performance; the soil between the vertical and inclined piles plays a role similar to an earth berm; additionally, the entire retaining system is similar to a gravity retaining wall, which has relatively high overturning stability.

Backcalculation of Finite-Element Modeling Based on Field Measurements Results of Excavation in Steel Sheet Pile Walls

“…The immediate behavior of the construction to refilling of the excavation is observed. The shadings of the vertical plastic strains ( Figures 7,11,15,18,22,26,29,34,and 37) show that excessive plastic strains are localized in the peat layer which has very poor geotechnical characteristics. The largest horizontal plastic strains are located on the top of the soil ground in contact with steel sheet pile walls (Figures 8,12,16,19,23,27,30,35,and 38).…”

“…The environmental stresses of structures and the soil around a retaining structure change over time, especially with fluctuations in the water table, and soil resistance decreases. Improper design of the excavation support structure can lead to serious engineering accidents and cause significant economic losses [13][14][15]. Therefore, it is necessary to take measures to considerably reduce the ground movements resulting from excavation and to control the parameters that guarantee proper operation under conditions of unquestionable safety, taking into account the interaction between the different parts of the geotechnical structure [4,16].…”

State-of-the-art requirements verification process applied to numerical finite-element modelling of the deep excavation in soft soils

“…The earth pressure acting on the retaining structure changes with time, while the soil strength reduces as a result of creep. Unreasonable design of the retaining structure of the foundation pit as well as the construction plan may lead to serious engineering accidents and cause great economic loss [13][14][15][16]. Therefore, it is extremely important to minimize excavation induced effects and control deformation for geotechnical structure interaction safety, affected by various factors [4,16].…”

A Modified Elastic Foundation Beam Method for Analyzing Lateral Wall Deformation in Excavations with Cross Wall

“…Recently, the diaphragm wall with cross walls was applied as a novel retaining structure system to reduce wall deformation in some areas of Asia [11][12][13][14][15][16]. As shown in Figure 1, cross walls were constructed perpendicularly to the diaphragm wall using the same diaphragm wall construction technique.…”