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目的:研究固结应力水平对深部重塑粘土不排水剪切行为的影响,着重分析高、低固结压力作用下黏土力学响应的差异,并揭示这种影响和差异的内在机理。创新点:1.揭示重塑黏土的固结不排水剪切应力应变行为显著依赖固结应力水平的特点;2.发现上述与应力水平相关的应力应变响应与黏土微观结构等密切相关。方法:1.开展重塑深部黏土不同压力水平下(表2)的三轴等向固结不排水剪切试验;2.利用环境扫描电镜获得的颗粒结构特征,从微观结构角度揭示与压力相关的应力-应变、强度与孔隙水压响应的内在机理;3.在临界土力学框架内讨论高压下重塑深部黏土的临界状态特征(图13和14)。结论:1.固结压力水平对重塑黏土的应力-应变-强度特性有显著影响;2.随着固结压力的增加,软化现象和局部剪切带逐渐明显(图2和5),峰值应力以及相应轴向应变则不断减小(图8和9);3.在大于2 MPa的高压固结不排水试验中,其孔隙水压/轴向应变曲线明显不同于常压(图3);4.上述与压力相关的力学性质均与黏土微观结构相关(图6和12);5.高压下黏土难以达到所谓的临界状态。
Objective: To study the effect of consolidation stress on undrained shear behavior of deep remolded clay, and to analyze the difference of mechanical response of clay under high and low consolidation pressure and to reveal the intrinsic mechanism of this influence and difference. Innovations: 1. Reveal that the undrained shear stress-strain behavior of remolded clay depends significantly on the level of consolidation stress; 2. It is found that the above stress-strain-related stress-strain response is closely related to the clay microstructure. Methods: 1. Undeformed triaxial consolidation undrained shear tests under different pressure levels (Table 2) were carried out to remodel deep clay; 2. The structural features of particles obtained by environmental scanning electron microscopy were used to reveal the correlation between pressure and pressure The intrinsic mechanism of the stress-strain, strength and pore-water pressure response; 3. The critical state characteristics of remolded deep clay under high pressure are discussed within the framework of critical soil mechanics (Figs. 13 and 14). Conclusions: 1. Consolidation pressure has a significant effect on the stress-strain-strength characteristics of the remolded clay. 2. With the increase of the consolidation pressure, the softening phenomenon and the local shear band become obvious (Fig. 2 and 5) (Figure 8 and 9). 3. The pore water pressure / axial strain curve is significantly different from the normal pressure (Figure 3) at pressure consolidation and undrained test of more than 2 MPa, ; 4. The above-mentioned pressure-related mechanical properties are related to the clay microstructure (Figures 6 and 12); 5. It is difficult to reach the so-called critical state in high pressure clay.