Maximum surface settlement induced by shallow tunneling in layered ground

Abstract

Purpose. To improve the prediction of maximum surface settlement induced by tunneling in multilayered soils. At the design stage, geotechnical experts tend to use simplified formulas for evaluating the ground response. Methodology. To examine the accuracy of empirical equations in predicting maximum surface displacement, two widely adopted formulas are considered for the current study: "Volume Loss" and "Farmer and Attewell". Moreover, because both equations are "inflection ratio" dependants, all existing expressions of the inflection parameter are taken in consideration. Finally, the obtained results are compared with field measurements, and the best pair of the expressions ("MSS" and "inflection ratio") is chosen. findings. Prediction of the maximum surface settlement due to shallow tunneling in soft grounds is a valuable indicator in ensuring safe operations, particularly in urban areas. The current paper clarifies the advantage of the VL method over Farmer and Attewell for all scenarios (variable overburden); high values of the VL improve the predictions significantly when it is combined with Dindarloo formulation of inflection ratio. originality. The originality of this work is the examination of the most adopted empirical methods and all inflection point formulas, to estimate the maximum surface settlement induced by the construction of 'Algiers Subway System' tunnel project; also, the paper demonstrated the weakness of some mostly used approaches through practical measurements. Practical value. Because of the lack of data in geotechnical engineering, this paper is a rich resource for tunneling projects in future because it covers over sixty measurement transverse profiles, and suggests numerical values for better assessment.