多场作用下压实膨润土剪切特性研究进展

Review on Shear Properties of Compacted Bentonite Under Multi-field Action

摘要:

膨润土剪切特性对维持深地质处置库工程屏障性能至关重要。概述了膨润土剪切特性受处置库近场环境作用的响应机理，归纳了膨润土剪切强度预测模型的最新进展。应力作用下，膨润土剪切强度增加有赖于单位体积内固相增多和孔隙数量减少；吸力作用下，剪切行为受控于吸附水膜的润滑和土颗粒间的摩擦作用等；化学作用下，溶液浓度、阳离子交换反应和矿物相变（碱性条件）是剪切行为改变的关键因素；温度作用下，伊利石化和微观结构重排使剪切强度出现不可逆增加；多场耦合作用下，剪切特性受各因素相互作用的复杂影响，目前这方面研究还不够深入。现阶段吸力作用下剪切强度预测模型较为成熟；化学作用下模型仅考虑化学溶液类型和浓度，忽视了阳离子交换作用、矿物溶解等影响。综上，对于多场耦合作用的剪切行为、膨润土裂缝自愈后剪切强度劣化问题和提高预测模型准确性等方面仍需展开进一步研究。

Abstract:

The shear characteristics of bentonite are crucial for maintaining the engineering barrier performance of deep geological repositories. We summarize the response mechanisms of bentonite shear characteristics to the repository’s near-field environment and review recent advancements in shear strength prediction models. Under stress， increases in bentonite shear strength are influenced by a rise in solid phase content and a reduction in pore volume per unit. Under suction conditions， shear behaviors are governed by the lubricating effect of the adsorbed water film and the friction between soil particles. Chemical interactions affect shear behaviors through factors like solution concentration， cation exchange reactions， and mineral phase transitions （under alkaline conditions）. Temperature effects， such as illitization and microstructural rearrangement， cause an irreversible increase in shear strength. Under multi-field coupling conditions， the shear properties are influenced by the intricate interactions among various factors， yet current research in this area remains insufficient. While current prediction models for shear strength under suction are well-developed， chemical interaction models mainly consider solution type and concentration， overlooking the roles of cation exchange and mineral dissolution. Given these limitations， further studies are needed to examine the shear behavior under multi-field coupling， assess the deterioration of shear strength following bentonite self-healing， and enhance the accuracy of prediction models.