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为研究主应力轴旋转复杂动应力对偏压固结粉土的性状演变影响,以空心圆柱试样为对象,开展具有不同初始固结比的密实粉土(Dr=70%)在不排水主应力轴循环旋转下的系列试验。结果表明:①初始固结比不大于1.5时,主应力轴旋转导致试样发生中低应变崩塌,进而液化的脆性破坏模式;而固结比大于1.5时,试样变为应变持续稳定开展至高应变,孔压最终进入动态平衡的延性破坏模式,且不同固结比下试样发生崩塌液化和稳态延性破坏的孔压峰值间不存在交叉。②小偏压固结试样的液化峰值孔压和崩塌孔压均随固结比增加而有规律地下降,但受动剪应力水平影响很小,这与等压固结试样的崩塌孔压值受控于剪应力水平有很大差异。③相同初始球应力水平下,崩塌振次反映的小偏压固结试样强度高于等压固结试样,但在偏压条件下强度与固结比不存在单调变化关系,表明小偏压固结试样崩塌除受制初始围压水平外,很大程度上还取决于偏压程度。④基于上述试验结果,提出了主应力轴循环旋转下小偏压固结粉土的孔压预测模型,该模型不仅突显了崩塌状态对相变及液化破坏的重要预测作用,还反映了固结比和动剪应力对孔压开展的综合影响。
In order to study the influence of complex dynamic stress of rotation of principal stress axis on the evolution of the properties of the biased consolidated silt, dense solid silt (Dr = 70%) with different initial consolidation ratios was developed for hollow cylindrical specimens. A series of tests under cyclic rotation of stress axis. The results show that: (1) When the initial consolidation ratio is no more than 1.5, the rotation of the principal stress axis leads to the low-strain collapse and liquefaction of the specimens, while the consolidation ratio is greater than 1.5, Strain and pore pressure eventually entered the dynamic equilibrium ductile failure mode, and there was no cross-over between the pore pressure peaks at the collapsing liquefaction and steady-state ductile failure under different consolidation ratios. (2) The peak pore pressure and collapse pore pressure of the LPB specimens decreased regularly with the increase of the consolidation ratio, but the influence of the shear stress level was small. This was in agreement with the collapse holes Pressure values controlled by shear stress levels vary widely. ③ Under the same initial ball stress level, the strength of the small-stress consolidation specimens reflected by the collapse vibrations is higher than that of the isobaric consolidation specimens, but there is no monotonous change in the strength and consolidation ratio under the bias conditions, In addition to the initial confining pressure, the collapse of the consolidation test specimen depends to a large extent on the degree of bias. (4) Based on the above test results, the pore pressure prediction model of small offset consolidation silt under the rotation of principal stress axis is proposed. The model not only highlights the important predictive effect of collapse on phase transition and liquefaction, but also reflects the consolidation The combined effect of ratio and dynamic shear stress on pore pressure.