Abstract
In geotechnical engineering, ground movement caused by excavations is a challenging issue. The excessive differential settlement generated by soil movement induced by wall deflection may cause damage to nearby structures. A detailed literature review on the general deformation behavior of deep excavation support systems is presented in this paper. Many factors, such as normalized horizontal deflection (δh-max/He%), vertical displacement (δv-max/He%), δvmax/δhmax ratio, settlement influence zone (Do), etc., can play significant roles in describing the deflection behavior of the excavation system. A descriptive analysis of the reviewed data was carried out. The concluded δh-max/He% values range between 0.17 to 1.5, with a mean value of 0.58 for soft clay, while in the case of sands and stiff clay soils δh-max/He% value ranges between 0.07 to 0.40, with a mean value of 0.20. δv-max/He% values range between 0.13 to 1.10, with a mean value of 0.49 for soft soil, while its value ranges between 0.02 to 1.10, with a mean value of 0.24 in the case of sands and stiff clay soils. The settlement influence zone (Do) reaches a mean distance of 2.3He, which falls within Do=1.5-3.5He in the case of soft clays, while Do reaches a mean distance of 2.0He and 3.0He in the case of sands and other stiff clay soils, respectively. The relationship between system stiffness and excavation-induced wall and ground movements was discussed. Unfortunately, the literature review offers limited data regarding system stiffness, the 3-D nature of excavation support systems, excavation processes, and time effects.
Highlights
Retaining systems can be classified according to several different criteria: construction method, load support mechanism, system stiffness, stability mechanism, applications, and lifespan [1]
The results showed that if the complementary error function (ERFC) is used, only geometry and maximum movement parameters shall be required to define the ground movement pattern
The reported δvmax/δhmax values range between 0.2% to 5.50%, with a mean value of 1.63% in the case of soft soil
Summary
Retaining systems can be classified according to several different criteria: construction method (fill or cut systems), load support mechanism (externally or internally stabilized systems), system stiffness (rigid or flexible systems), stability mechanism, applications, and lifespan (permanent or temporary systems) [1]. The stresses in the earth mass fluctuate due to excavation activities [6,7,8,9,10] These changes are manifested by lateral wall deformations and ground surface settlements and these movements can describe the performance of excavation support systems [11]. It can be seen that the adjacent structures may be affected by the severe differential settlement resulting from the ground settlement due to lateral wall deformation Such potential effect is magnified when deep excavation occurs in a densely populated urban area where excavation activities are carried out adjacent to the structures [26]
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