Study on the basal-heave stability and reliability of foundation pit considering excavation width and thickness of soft soil layer
Basal-heave is one of the key factors affecting the stability of foundation pit.This study aims to investigate the influence of excavation width and the thickness of soft soil layer on the basal-heave deformation and basal-heave stability and reliability.Firstly,finite ele-ment models are established for different working conditions to obtain the substrate deform-ation data of the characteristic points at the bottom of the foundation pit and analyze their de-formation laws.Secondly,the limit state functions are established in terms of acceptable basal-heave deformation.Finally,the Monte Carlo method is used to perform probabilistic analysis of the pit bottom.Numerical simulation results show that for narrow pits,when the thickness of the soft soil layer is sufficiently enough to guarantee the complete generation of failure zones,there are large deformations on the two sides of the foundation pits and small deformations in the middle.Conversely,for wide pits,there are large deformations in the middle of the foundation pits and small deformations on the two sides.For both types of pits,the deformation of basal-heave increases with the increase of pit width.Changing the thickness of the soft soil layer,the deformation of each characteristic point changes accord-ingly,and the basal-heave deformation remains small in the middle and large on both sides for narrow pits.With the increase of the thickness of the soft soil layer,the value of basal-heave deformation at each characteristic point of the pit bottom increases,and the basal-heave deformation at the center of the pit bottom gradually exceeds deformation at both sides for wide pits.According to the deformation law,we can obtain the thickness of the soft soil layer when the thickness is sufficiently enough to guarantee the complete generation of fail-ure zones.The stability and reliability of basal-heave is hinged on the width of pits,the loca-tion of each characteristic point and the thickness of the soft soil layer.The stability of the pit bottom and the location of the characteristic point with the lowest reliability index varies with the width of the pit and the thickness of the soft soil layer.
foundation pit engineeringbasal-heave stability and reliability of foundation pitresponse surface methoddeformation value of foundation pitreliability index
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