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Strength Reduction Finite Element Analysis of Soil Slope Stability

Author: PeiLiJian
Tutor: QuBenNing
School: Kunming University of Science and Technology
Course: Engineering Mechanics
Keywords: Finite Element Method Strength Reduction Safety factor Instability criterion Strength criteria Accuracy Analysis
CLC: TU43
Type: Master's thesis
Year: 2009
Downloads: 230
Quote: 1
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Abstract

Finite element strength reduction as a more complete theory of slope stability analysis methods, to the inception increasing people's attention. In this paper, the method instability criterion, strength criteria, safety factor search, finite element calculation accuracy and properties of solutions and several other issues were analyzed. Studies show that: for plane strain problems can be associated flow rule under plane strain Mohr - Coulomb strength criterion matches the DP (MC inscribed circle criterion) or plane strain under non-associated flow rule Mohr - Coulomb strength criterion matches the DP, generally strict limit equilibrium calculations slice method is closer, with high accuracy. Their interaction within the gap of about 3%. The current popular finite element numerical iterative non-convergence criterion, the characteristic parts of the displacement mutation criteria, generalized plastic strain or equivalent plastic strain through criteria such as three criteria in theory unity and consistency. And the finite element numerical iterative convergence criterion is not the most convenient to use and reliable. Strength reduction finite element mesh model calculation accuracy and selection are closely related. The more coarse mesh, and the resulting larger safety factor, whereas the safety factor is smaller. Different degrees of mesh density between calculation results obtained up to 5% or more of the gap. It is only when the grid fine enough, the resulting safety factor was close to exact solution or true value. So a sufficiently fine mesh model for improving the degree of accuracy is very necessary. The use of local mesh refinement, whichever side length of mesh refinement zone slope height of 1/30 or so can achieve a higher accuracy and less time-consuming. Model boundary little effect on accuracy. Take as long as the boundary of the model calculation is slightly larger than the potential slip surface (or slip) position to do so can make the model as small as possible, thereby reducing the amount of computation, computational efficiency. Slope soil modulus E and Poisson's ratio v is small deformation of the safety factor of the results of small. Relation sinφ ≥ 1-2v safety factor for the calculation is unnecessary. Finite element strength reduction obtained with a maximum of safety factors. Strength Reduction FEM calculation theory more perfect, it is generally the case that the method has higher reliability. This method has the ceiling, and its calculation results are generally too large, unsafe, and the limit equilibrium method (strict slice method) resulting safety factor greater than the strength reduction (about 1% to 3%), it is reason to say that the limit equilibrium method (strict slice method) calculations are somewhat higher unsafe.

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