A filtration model for evaluating maximum penetration distance of bentonite grout through granular soils
A filtration model for evaluating maximum penetration distance of bentonite grout through granular soils
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DOI：
10.1016/j.compgeo.2015.01.004
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发表时间：
2015-04
影响因子：
5.3
通讯作者：
Jisuk Yoon;C. E. Mohtar
中科院分区：
文献类型：
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作者：
Jisuk Yoon;C. E. Mohtar
本文提出了一种计算化学改性膨润土灌浆最大渗透距离的过滤模型。高浓度膨润土灌浆需要进行化学修饰以增加其对土壤的渗透；然而，由于膨润土灌浆的物理化学和流变性的变化，这种修饰使最大渗透距离的评估变得复杂。在本研究中，通过将本构模型(Herschel-Bulkley模型)与流变学试验得到的剪切应力-剪切速率曲线进行匹配，确定了经1~4%焦磷酸钠(SPP)改性的7.5%、10%和12%膨润土浆的屈服应力。将膨润土浆注入砂柱，注入压力分别为35或140 kpa。利用解析方程(基于浆液的屈服应力)计算了膨润土浆液通过砂柱的最大贯入距离，并与实测的最大贯入距离进行了比较。结果表明，解析方程能较好地反映高屈服应力下(大于280pA)的最大侵彻距离，但由于过滤的影响，在低屈服应力下的最大侵彻距离被严重高估了。本文提出了一种新的过滤模型来估算SPP改性膨润土灌浆的最大渗透距离，该模型可以提供更好的预测，特别是对于低屈服应力的灌浆。该模型基于一维柱试验进行了校准，然后使用不同化学成分的膨润土进行了另外一组柱试验的独立验证。
This paper presents a filtration model for evaluating the maximum penetration distance of chemically modified bentonite grouts. High-concentration bentonite grouts require chemical modifications to increase its penetration through soils; however, this modification complicates the evaluation of the maximum penetration distance due to the changes in the physicochemical and rheological properties of the bentonite grout. In this study, the yield stresses of 7.5%, 10%, and 12% bentonite grouts modified by 1–4% sodium pyrophosphate (SPP) (by dry weight of bentonite) were determined by matching a constitutive model (Herschel–Bulkley model) to the shear stress–shear rate curves obtained through rheological tests. The bentonite grouts were injected into sand columns with an injection pressure of 35 or 140 kPa. The maximum penetration distances of the bentonite grouts through the sand columns were calculated using analytical equations (based on the yield stress of the grouts), and then compared to the measured maximum penetration distances. The results showed that the analytical equations could capture the maximum penetration distance at high yield stress (greater than 28 Pa), but the equations significantly overestimated the maximum penetration distance at low yield stress due to filtration. A new filtration model is presented in this study to estimate the maximum penetration distance of the SPP modified bentonite grouts that can provide better prediction, particularly for grouts having low yield stresses. The model was calibrated based on the 1-D column tests and then independently validated with an additional set of column tests using a bentonite with different chemical composition.