化–力耦合条件下膨润土的体变特性

doi:10.13722/j.cnki.jrme.2018.0837

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摘要在处置库长期运营中，由于地下水水位、温度等变化导致地下水离子浓度变化，围岩和废物罐的限制产生反压力，不可预知的地质构造活动或者地质环境变化导致附加应力变化都会影响缓冲/回填材料的体变。为模拟缓冲/回填材料在地下水离子浓度和附加应力变化下的体变情况，在不同化学–力学应力路径下，以不同浓度NaCl溶液和去离子水作为入渗溶液，采用高压固结仪对干密度1.6 g/cm3的膨润土试样进行膨胀–压缩–回弹试验，从宏观和微观的角度系统地分析膨润土在化–力耦合条件下的体变特性。结果表明，随着NaCl溶液浓度增加，膨润土试样的最终膨胀率及压缩指数减小。通过对经历淡化(入渗溶液由盐溶液替换为去离子水)–盐化(入渗溶液由去离子水替换为原盐溶液)循环与未经历该循环的试样体变特性对比发现宏观结构塑性性状在一定程度上表现出不可逆性状，而微观结构性状是可逆的。在淡化循环下，随着循环前溶液浓度的增加以及循环时竖向应力的减小，循环膨胀率随之增加。

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	秦爱芳
	傅贤雷
	孙德安
	阮坤林
	李天义

关键词 ：土力学, 膨润土, 化学–力学应力路径, 处置库, 微观结构

Abstract：The volume change of the buffer/backfill materials in geological repositories is affected by several factors during the long-term operations. For example，the variation of ion concentration in groundwater caused by the fluctuation of groundwater level and temperature，the variation of additional stress caused by the changing geological tectonic activity and geological environmental，and the backpressure from the restriction of surrounding rock and waste container. To simulate the volume change of the buffer/backfill materials affected by above-mentioned factors，a serial of swell-compression-rebound tests have been conducted on as-prepared compacted bentonite specimens with initial dry density of 1.6 g/cm3 using high-pressure consolidometer. Deionized water and NaCl solutions with different degrees of concentration were used as infiltration solutions. And these tests were performed under different chemo-mechanical stress paths. The volume change behaviours of the compacted bentonites under coupled chemo-mechanical conditions in these tests were systematically analyzed from the macro and micro perspectives. The results show that the final swelling strain and compression index of bentonite samples decrease with increasing NaCl solution concentration. By comparing the volume change behaviours of samples underwent desalination-salinization cycle with those did not undergo this cycle，it is found that the plastic behaviour of macrostructure is irreversible，while microstructural behaviour is reversible. For the samples under the desalinization cycle，with the increase of solution concentration and decrease of vertical stress，the final cycle swelling strain increases.

Key words： soil mechanics bentonite chemo-mechanical stress paths geological repository microstructure

引用本文:

秦爱芳，傅贤雷，孙德安，阮坤林，李天义. 化–力耦合条件下膨润土的体变特性[J]. 岩石力学与工程学报, 2019, 38(S2): 3775-3782.
QIN Aifang，FU Xianlei，SUN De?an，RUAN Kunlin，LI Tianyi. Influences of chemo-mechanical coupling on the volume change behaviour of bentonite. , 2019, 38(S2): 3775-3782.

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http://rockmech.whrsm.ac.cn/CN/10.13722/j.cnki.jrme.2018.0837 或 http://rockmech.whrsm.ac.cn/CN/Y2019/V38/IS2/3775

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