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基于三剪统一强度准则和非饱和土双应力状态变量抗剪强度,考虑中间主应力效应、材料拉压不等特性和强度准则差异的影响,建立了非饱和土抗剪强度三剪统一解,并在此基础上推导了非饱和土条形地基太沙基极限承载力的计算公式。通过可行性分析及算例论证,验证了所推公式的正确性,探讨了中间主应力效应、强度准则、基质吸力、有效内摩擦角和有效黏聚力等参数对非饱和土条形地基极限承载力的影响规律。研究结果表明:中间主应力效应和强度准则对非饱和土条形地基太沙基极限承载力具有显著影响,中间主应力效应越显著,极限承载力越高,说明考虑中间主应力效应可以更加充分发挥材料的强度潜能,也说明强度准则差异对地基极限承载力的预测具有重要作用。基质吸力对非饱和土条形地基太沙基极限承载力具有双重影响:在低基质吸力范围内,极限承载力随基质吸力的增大线性提高;当基质吸力增大到进气值时,极限承载力达到峰值;在高基质吸力范围内,极限承载力随基质吸力的增大逐渐降低,最终趋于稳定。非饱和土条形地基太沙基极限承载力随有效内摩擦角和有效黏聚力的增大显著提高。非饱和土太沙基极限承载力三剪统一解包含了多种屈服准则下地基承载力的计算公式,具有较广泛的适用性,可为实际工程应用提供参考。
Based on the triple shear unified strength criterion and the bi-stress state variables of unsaturated soils, considering the influence of intermediate principal stress effect, material tension and pressure difference and the difference of strength criterion, a three-shear unified solution of unsaturated soil shear strength is established. On this basis, the formula for calculating the ultimate bearing capacity of unsaturated soils in strip-shaped foundation is deduced. Through the feasibility analysis and case demonstration, the correctness of the formula is verified, and the effects of the intermediate principal stress effect, strength criterion, matrix suction, effective internal friction angle and effective cohesion on the strip foundation of unsaturated soils Influence law of bearing capacity. The results show that the intermediate principal stress effect and strength criterion have a significant effect on the ultimate bearing capacity of unsaturated soils, and the more obvious the intermediate principal stress effect and the higher ultimate bearing capacity, which means that the effect of intermediate principal stress can be more sufficient It also shows that the difference of strength criterion plays an important role in predicting the ultimate bearing capacity of foundation. The matrix suction has a dual effect on the ultimate bearing capacity of unsaturated soils: in the range of low matrix suction, the ultimate bearing capacity increases linearly with the increase of matrix suction; when the matrix suction increases to the inlet value, the limit In the range of high substrate suction, the ultimate bearing capacity gradually decreases with the increase of substrate suction, and eventually becomes stable. The ultimate bearing capacity of overdentant base in unsaturated soil strip foundation is significantly increased with the increase of effective internal friction angle and effective cohesion. The three-shear unified solution of unsaturated soil emery base contains the calculation formula of the bearing capacity of foundation under a variety of yield criteria, which has a wide range of applicability and can be used as a reference for practical engineering application.