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Abstract A finite element method(FEM) is proposed to solve the excavation problem in sand. Based on the existing research achievements of stress release and elastic-plastic unloading theory of bulk solids，the non-linear characteristics of load-displacement curve is equivalent to the gradually release process of the excavation load，during which the loading modulus is the same with the unloading one. The excavation load considering the internal friction resistance of material is deduced，after introduce the octahedral shear stress to calculate the internal friction force according to the existing research achievements，the relationship between the internal friction resistance of material and the residual stress during excavation is established according to the virtual work principle；and the FEM of stress release，which takes the excavation load into consideration，is carried out by adjusting the unloading stiffness of material during excavation on the basis of stress release properties. The derivation of node equilibrium equations indicates that the excavation load has influence on the whole computational domain and also has corresponding relation with the stress release effect；A static loading-unloading model test of sand was designed and simulated by the proposed FEM as well；the residual stress calculated by this FEM was basically identical with the results of the test，and can be also explained by the existing stress release research results. Therefore，this FEM provides the calculation of excavation problem with a numerical simulation method.
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2015, Vol. 34 
