考虑渗透吸力影响膨润土的修正有效应力及其验证

Modified effective stress induced by osmotic suction and its validation in volume change and shear strength of bentonite in saline solutions

普遍认为膨润土是高放废物地质处置库缓冲/回填层的理想材料,膨润土在地下水溶液中的膨胀变形和剪切强度关乎高放废物地质处置库的安危。地下水溶液中膨润土膨胀变形和剪切强度受到渗透吸力影响,根据膨润土表面分形模型,建立考虑渗透吸力应力影响的修正有效应力公式,用竖向应力p和渗透吸力π表示为■,并采用膨润土在NaCl溶液中的膨胀变形和剪切强度进行验证。NaCl溶液中膨润土的膨胀变形与修正有效应力p^e表示为同一曲线■,峰值剪切强度与修正有效应力p^e表示为同一直线■,符合Mohr–Coulomb准则。

Bentonite is widely seen as a potential buffer/backfill materials for deeply buried geological disposal system to isolate high-level radioactive waste(HLRW).The swelling deformation and shear strength of the bentonite in saline solutions are very important to the safety of the HLRW depository.A conceptual model is proposed to explain the influences of osmotic suction on the volume change and shear strength of the bentonite in a quantitative way.A new formula for the effective stress is proposed as pe=p+pπincorporating with vertical stress(p)and osmotic suction(π),andpe=p+(p/π)Ds-2π.The e m e-p relationship is expressed using a unique curve in the form of em=K(pe)Ds-3 for the bentonite in NaCl solutions.The peak shear strength is expressed using a unique curve according to the Mohr–Coulomb criterion for the bentonite in NaCl solutions.