Abstract:

Natural structural soil is susceptible to various types of construction disturbance. The disturbance results in the change of the physical and mechanical properties of soil, which in turn the engineering stability, deformation and adjacent environment. In this paper, triaxial tests and one-dimensional compression tests were carried out on undisturbed soil, lightly disturbed soil, heavily disturbed soil and remolded soil of two typical soils in Ningbo. The influence of disturbance degree on the main parameters of HSS model was analyzed, the influence laws were applied to a foundation pit project in Ningbo City. The horizontal displacement of the foundation pit was analyzed with Plaxis3D considering the influence of surrounding soil disturbance. The results show that disturbance has adverse effects on the strength and stiffness of soil. For mucky clay, the reference tangent modulus E^ref_oed, reference secant modulus E^ref₅₀ and reference loading/unloading modulus E^ref_ur of lightly disturbed samples are respectively reduced by 14%, 10% and 2%, the above parameters of the heavily disturbed sample are reduced by 43%, 14% and 15% respectively, and similar decreasing laws can also observed in silty clay. Considering the influence of soil disturbance, the maximum calculated horizontal displacement of the two inclined holes around the foundation pit increases by 13% and 15% respectively, which is closer to the measured values. The research results can provide a guidance for HSS model parameter selection and foundation pit engineering analysis and calculation considering disturbance effect.

Key words: structural, disturbance, HS-small model (HSS model), stiffness parameters, excavation of foundation pit