A closed form shape function describing 3D settlement field around a deep excavation in sand

Area of Science:

• Geotechnical Engineering
• Computational Mechanics

Background:

• Deep excavations in urban areas generate significant soil movements, posing challenges for underground structure design.
• Existing methods, including 2D semi-empirical and numerical (FEM/DFM) models, have limitations in predicting comprehensive ground settlement patterns.

Purpose of the Study:

• To develop and validate a novel 3D analytical model for predicting ground settlement troughs around deep excavations.
• To establish relationships between excavation geometry and the parameters of the proposed 3D subsidence function.

Main Methods:

• Review and modification of existing 2D semi-empirical methods.
• Development of a new 3D analytical subsidence function with shape and scale parameters.
• Conducting 3D nonlinear finite element method (FEM) parametric studies based on real case studies.
• Fitting the proposed 3D model to FEM results and validating it with case studies in sand.

Main Results:

• The proposed 3D analytical description effectively fits FEM-generated settlement fields.
• Fundamental relationships were identified between excavation geometry and the parameters of the 3D subsidence function.
• Validation against three case studies of deep excavations in sand showed satisfactory agreement.

Conclusions:

• The new 3D analytical model provides a more comprehensive description of subsidence troughs compared to existing methods.
• The identified relationships offer practical tools for estimating ground movements based on excavation characteristics.
• The model shows promise for improving the design and construction of underground structures in urban environments.