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State of compacted bentonite inside a fractured granite cylinder after infiltration
Applied Clay Science ( IF 5.6 ) Pub Date : 2020-03-01 , DOI: 10.1016/j.clay.2020.105438 Xia Bian , Yu-Jun Cui , Ling-Ling Zeng , Xiao-Zhao Li
Applied Clay Science ( IF 5.6 ) Pub Date : 2020-03-01 , DOI: 10.1016/j.clay.2020.105438 Xia Bian , Yu-Jun Cui , Ling-Ling Zeng , Xiao-Zhao Li
Abstract A small-scale mock-up test was carried out on a fractured hollow granite cylinder with compacted MX80 bentonite inside, to study the interaction between engineered barrier (compacted bentonite) and natural barrier (host rock with the presence of rock fracture). The swelling pressure and relative humidity of bentonite were monitored with respect to the position of the rock fracture during 349 days of infiltration. Herein, the variation of water content, dry density, suction and microstructure along bentonite column after dismantling were reported, focusing on the changes in the vicinity of the rock fracture, to evaluate the effect of the rock fracture on the swelling behaviour of compacted bentonite. Results showed that the presence of rock fracture disturbed the water content distribution, with a lower water content at a position closer to the fracture. A significant decrease in dry density was also observed in the vicinity of the rock fracture; the closer the positions to the fracture the larger the decrease of dry density. This decrease coincided with the reduction of swelling pressure recorded by the pressure sensors, suggesting the occurrence of rock fracture filling-up by bentonite. Further examination showed that when the soil suction was higher than 9 MPa, the decrease in dry density in the near field of rock fracture was mainly attributable to the increase in large pore porosity (>2 μm). This suggests that at this suction the mechanism involving intrusion of bentonite into the rock fracture with fracture width higher than the size of bentonite gains was related to the pushing effect under the swelling of bentonite behind. By contrast, when the suction became lower than 9 MPa, the bentonite gel formed from the exfoliation of clay particles might fill up the rock fracture with smaller aperture width.
中文翻译:
渗透后破碎花岗岩圆柱体内压实膨润土的状态
摘要 为了研究工程屏障(压实膨润土)和天然屏障(存在岩石断裂的围岩)之间的相互作用,对内有压实MX80膨润土的断裂空心花岗岩圆柱体进行了小规模模拟试验。在 349 天的渗透过程中,根据岩石裂缝的位置监测膨润土的膨胀压力和相对湿度。本文报道了拆解后膨润土柱的含水量、干密度、吸力和微观结构的变化,重点关注岩石裂缝附近的变化,以评估岩石裂缝对压实膨润土膨胀行为的影响。结果表明,岩石裂缝的存在扰乱了含水量分布,在靠近裂缝的位置具有较低的含水量。在岩石裂缝附近也观察到干密度显着降低;离裂缝越近,干密度下降幅度越大。这种降低与压力传感器记录的膨胀压力的降低相吻合,表明膨润土填充了岩石裂缝。进一步研究表明,当土壤吸力大于9 MPa时,岩石破裂近场干密度的降低主要归因于大孔隙孔隙度(> 2 μm)的增加。这表明在这种吸力下,膨润土侵入岩石裂缝且裂缝宽度大于膨润土增益尺寸的机制与后面膨润土膨胀下的推动作用有关。
更新日期:2020-03-01
中文翻译:
渗透后破碎花岗岩圆柱体内压实膨润土的状态
摘要 为了研究工程屏障(压实膨润土)和天然屏障(存在岩石断裂的围岩)之间的相互作用,对内有压实MX80膨润土的断裂空心花岗岩圆柱体进行了小规模模拟试验。在 349 天的渗透过程中,根据岩石裂缝的位置监测膨润土的膨胀压力和相对湿度。本文报道了拆解后膨润土柱的含水量、干密度、吸力和微观结构的变化,重点关注岩石裂缝附近的变化,以评估岩石裂缝对压实膨润土膨胀行为的影响。结果表明,岩石裂缝的存在扰乱了含水量分布,在靠近裂缝的位置具有较低的含水量。在岩石裂缝附近也观察到干密度显着降低;离裂缝越近,干密度下降幅度越大。这种降低与压力传感器记录的膨胀压力的降低相吻合,表明膨润土填充了岩石裂缝。进一步研究表明,当土壤吸力大于9 MPa时,岩石破裂近场干密度的降低主要归因于大孔隙孔隙度(> 2 μm)的增加。这表明在这种吸力下,膨润土侵入岩石裂缝且裂缝宽度大于膨润土增益尺寸的机制与后面膨润土膨胀下的推动作用有关。