Application Of Hardening Soil Model With Small-strain In Deformation Analysis For Foundation Pit

The deformation of foundation pit has heavy impacts on the adjacent ambience. Therefore, accurate prediction of the deformation of the foundation pit is critical in foundation engineering. Numerical analysis has been proved to be an effective means to predicting the deformation of the foundation pit. However, properly determining the constitutive model and choosing the involved parameters in numerical modeling are still two aspects that need to be further studied.By comparing between the results from Hardening Soil Small (HSS) constitutive model and several other constitutive models in PLAXIS programme, the characteristics for a constitutive model suitable for the deformation of the foundation pit have been analyzed. Referring the soil mechanical properties provided in Geo-technical Engineering Report (GER), a selection scheme for soil mechanical properties has been established, from which all the soil properties required in HSS constitutive model in PLAXIS programme can be obtained. The chosen constitutive model and the soil properties choosing method are validated by comparing the numerical modeling results with the field records from two practical foundation pits. The following main conclusions can be reached:(1) Biased on the comparison among the numerical results from commonly-used constitutive models, it can be found that if the constitutive model could model the effects of soil shear hardening, compression hardening and the unloading plastic deformation, the constitutive model would be reasonably good in the deformation analysis in foundation pit engineering. Moreover, it can also be found that if the constitutive model could model the effects of soil mass during the small strain stage, the constitutive model would be more suitable.(2) The scheme for determining soil mechanical properties required by HSS constitutive model from GER has been summarized. The scheme is summarized in a table.(3) By comparing the numerical results using HSS constitutive model and the field records from two practical foundation pits, it can be found that the HSS constitutive model can properly the deformation of foundation pit, moreover the soil mechanical property method given by current research is reasonable.(4) The impacts of soil hardening and small-strain phenomenon on foundation pit deformation have been analyzed.