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基于非饱和土的抗剪强度统一解,综合考虑中间主应力、基质吸力和强度非线性,建立非饱和土条形地基的梅耶霍夫极限承载力统一解,对比文献滑移线法解答、上限法解答验证所得统一解的正确性和适用性,讨论与太沙基极限承载力的差异及基底粗糙程度效应,并得出中间主应力、高/低基质吸力以及有效强度参数的影响规律。研究结果表明:太沙基极限承载力将旁侧土的抗剪强度简化为均布荷载,夸大了旁侧土的真实作用,计算结果偏大;基底粗糙程度对承载力系数的确定起关键性作用,梅耶霍夫极限承载力随中间主应力效应的增大而显著增加,不考虑中间主应力影响的Mohr-Coulomb解答过于保守;基质吸力具有双重影响:在低吸力范围内极限承载力线性增加,而在高吸力范围内却逐渐减小并趋于稳定,这是由非饱和土的强度非线性造成的;有效强度参数的影响亦很重要,且有效内摩擦角较有效黏聚力的影响更明显。由于考虑了中间主应力效应、非饱和特性与旁侧土抗剪强度等工程实际情况,本文结果可为地基优化设计与施工提供有益的参考。
Based on the unified solution of shear strength for unsaturated soils, the unified solution of Meyerhoff’s ultimate bearing capacity is established by comprehensive consideration of intermediate principal stress, matrix suction and strength nonlinearity. Compared with the literature of slip line method, The upper bound method is used to verify the correctness and applicability of the unified solution. The difference between the ultimate bearing capacity and the basal roughness effect is discussed. The influences of the intermediate principal stress, the high / low matrix suction and the effective strength parameters are obtained. The results show that the ultimate bearing capacity of the terbuthylazine simplifies the shear strength of the side soil to a uniform load, exaggerating the true function of the side soil and the calculation result is too large. The roughness of the foundation plays a key role in determining the bearing capacity coefficient The Meyerhof’s ultimate bearing capacity increases significantly with the increase of the intermediate principal stress effect, and the Mohr-Coulomb’s solution without considering the influence of the intermediate principal stress is too conservative. The matrix suction has a dual effect: the linearity of the ultimate bearing capacity in the low suction range Increase, but decrease gradually and stabilize in the range of high suction, which is caused by the non-linear strength of unsaturated soil. The influence of effective strength parameters is also very important, and the effective internal friction angle is more effective cohesion The impact is more obvious. Due to the fact that the middle main stress effect, the non-saturated characteristic and the lateral soil shear strength are taken into account, the results of this paper can provide useful references for the foundation design and construction optimization.