基于归一化剪切模量的土样扰动评价方法研究

    Study on evaluation method for soil sample disturbance based on normalized shear modulus

    • 摘要: 目前关于土体取样扰动评价的诸多方法中,除了修正体积压缩法可以单独地反映土体结构损伤对取样扰动程度的影响,其它方法得到的扰动度均为应力水平和结构损伤的综合反映。本文提出一种基于归一化剪切模量的土样扰动评价方法,除了可以实现土体应力水平影响和结构损伤影响的解耦,单独体现土体结构的损伤程度,还能评价土样试验操作、上机固结后的扰动程度,实现土样从取样到制备,再到固结至原位应力状态时的结构性参数的追踪,定量评价各阶段的扰动程度,实现扰动全流程评价。研究结果表明:采用“归一化刚度法”评价取样扰动的结果与“修正体积压缩法”的误差基本不超过5%,说明以归一化刚度评价取样扰动是合理有效的;土样在试验操作、上机固结后的扰动度会进一步增加,相比于制样操作前,其扰动度增加约7%~15%。

       

      Abstract: Among various existing methods for evaluating soil sampling disturbance, only the modified volumetric compression method can independently reflect the influence of soil structural damage on the degree of sampling disturbance, while the disturbance degrees obtained by other methods are all comprehensive representations of both stress level and structural damage. This paper proposes a soil sample disturbance evaluation method based on normalized shear modulus. Besides decoupling the effects of soil stress level and structural damage to independently characterize the degree of soil structure damage, this method can also evaluate the disturbance degree of soil samples after experimental operation and consolidation in the testing apparatus. It enables the tracking of structural parameters of soil samples throughout the process from sampling and sample preparation to consolidation under the in-situ stress conditions, and quantitatively assesses the disturbance degree at each stage, thus achieving a full-process disturbance evaluation. The research results show that the error between the sampling disturbance evaluation results obtained by the "normalized stiffness method" and those by the "modified volumetric compression method" is basically within 5%, indicating that the evaluation of sampling disturbance using normalized stiffness is reasonable and effective; the disturbance degree of soil samples will further increase after experimental operation and consolidation, with an increase of approximately 7%~15% compared with that before sample preparation.

       

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