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通过SMP屈服准则,对砂土中柱孔扩张问题进行理论分析。以柱孔扩张理论为基础,利用孔周土体塑性区的边界条件和土体体积变化规律,推导柱孔扩张问题中初始半径a0,扩孔半径a和对应的扩孔压力p三者之间的理论关系。利用上述理论公式,得到平面应变条件下柱孔扩张问题的扩孔压力的极限值pu和孔周土体的弹塑性区域应力场、位移场,进而求得塑性区半径rp与扩孔压力p和初始孔径a0的关系。分析表明,该应力场和位移场分布规律仅与柱孔的初始半径a0和扩孔压力p相关。此外,应用应力场公式,推导散体材料桩极限强度表达式。最后通过算例分析,对柱孔扩张中应力场和位移场分布、塑性区半径和扩孔压力的变化规律进行分析。
Through the SMP yield criterion, the theoretical analysis of the expansion of column hole in sand is conducted. Based on the theory of column hole expansion, the boundary conditions of the plastic zone around the perimeter of the hole and the variation of soil volume are used to deduce the difference between the initial radius a0, the radius of expansion hole a and the corresponding expansion pressure p The theoretical relationship. By using the above theoretical formula, the limit value pu and the stress field and displacement field in the elastic-plastic region of the hole around the hole under plane strain are obtained, and then the relationship between the plastic zone radius rp and the expansion hole pressure p and Initial aperture a0 relationship. The analysis shows that the distribution of stress field and displacement field is only related to the initial radius a0 of the column hole and the pressure p of the expansion hole. In addition, by using the stress field formula, the ultimate strength expression of the bulk material pile is deduced. Finally, through the example analysis, the variation of stress field and displacement field, the radius of plastic zone and the pressure of expanding pressure were analyzed.