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以柱孔扩张理论为基础,将柱孔扩张后塑性区半径b作为时间刻度,引入扩孔速度概念,将塑性区内任意一点的应力、应变描述成塑性区半径b和柱孔扩张后扩张体单元距孔心距离r的函数,采用平面应变条件下无黏性土的SMP准则和不相关联流动法则,考虑到无黏性土的剪胀性,推导出柱孔扩张后极限扩张力Pli m的相似解。通过参数分析表明,土体强度和剪胀性对塑性区半径和极限扩张力产生很大的影响,即随着土体强度和剪胀性的增加,极限扩张力明显增加,相应塑性区半径却随之减小。通过与基于摩尔-库仑准则解答进行对比分析表明,考虑中间主应力影响的SMP准则所得到的极限扩张力明显高于基于摩尔-库仑准则的解答。该解答为无黏性土中进行静力触探(CPT)试验和静压桩等岩土工程问题提供必要的理论依据。
Based on the theory of column hole expansion, the radius b of the plastic zone after the expansion of the column hole is taken as the time scale, and the concept of hole expansion velocity is introduced to describe the stress and strain at any point in the plastic zone as the radius b of the plastic zone and the expansion body Based on the SMP criterion of cohesion-free soil under plane strain condition and the uncorrelated flow rule, considering the dilatancy of clayey soil, the ultimate expansion force Pli m Similar solution. The analysis of parameters shows that soil strength and dilatancy have a great influence on the radius of plastic zone and the ultimate expansion force. That is to say, with the increase of soil strength and dilatancy, the ultimate tensile strength obviously increases. The radius of the corresponding plastic zone With the reduction. Comparing the results with the solutions based on the Mohr - Coulomb criterion shows that the ultimate expansion force obtained by the SMP criterion considering the effect of intermediate principal stress is significantly higher than that based on the Mohr - Coulomb criterion. The solution provides the necessary theoretical basis for CPT test and geotechnical engineering such as static pressure pile in non-cohesive soil.