(1. School of Civil Engineering and Mechanics，Lanzhou University，Lanzhou，Gansu 730000，China；2. Key Laboratory of Mechanics on Disaster and Environment in Western China，Ministry of Education，Lanzhou University，Lanzhou，Gansu 730000，China)
Abstract：In the HLW repository，the strong alkaline solution precipitated by the corrosion of the lining concrete by the groundwater and the radiant heat released by the decay of the nuclide will affect the swelling performance of the buffer backfill material. The mixture of 70% bentonite and 30% quartz sand is used as the test object. Distilled water and KOH solution are selected for the pore solution，and the concentration of the solution is 0.1，0.3，1.0 mol/L. Set the test temperature to normal temperature and 90 ℃. Test the swelling pressure of samples with different initial dry densities. After the test was completed，X-ray diffraction(XRD) test was carried out on the sample. The test results confirmed that the high temperature increased the swelling pressure development rate and the swelling pressure value of the sample，and the final swelling pressure value increased by 19.3%. Under the action of KOH solution，the swelling pressure of the buffer backfill material decays over time，which is a typical feature of the alkali solution?s damage to the swelling performance. The final swelling pressure value is positively correlated with the KOH concentration and negatively correlated with the initial dry density. Under the action of 90 ℃ 1.0 mol/L KOH solution，the final swelling pressure value of the sample is higher than that of distilled water，and the attenuation degree reaches more than 52.3%. The attenuation of the sample is mainly related to the dissolution of montmorillonite and cation exchange. In the most severe case，the montmorillonite content is reduced to 43.2% of the initial.
张虎元1，2，季 泽1，周光平1，童艳梅1，王婷婷1. 高温碱溶液中混合型缓冲材料膨胀特性研究[J]. 岩石力学与工程学报, 2024, 43(S1): 3507-3519.
ZHANG Huyuan1，2，JI Ze1，ZHOU Guangping1，TONG Yanmei1，WANG Tingting1. Swelling pressure of bentonite-sand mixture buffer materials for HLW disposal as effected by both high temperature and alkaline solutions#br#. , 2024, 43(S1): 3507-3519.
崔素丽，张虎元. 静力压实混合型缓冲材料膨胀特性研究[J]. 辐射防护，2012，32(5)：289-295.(CUI Suli，ZHANG Huyuan. Study on the swelling characteristics of static compaction hybrid buffer materials[J]. Radiation Protection，2012，32(5)：289-295.(in Chinese))
[7]
彭 宇. 冰-土混合法提高膨润土砌块体材料均匀性[硕士学位论文][D]. 兰州：兰州大学，2017.(PENG Yu. Ice-soil mixing method to improve homogeneity of bentonite material for HLW disposal[M. S. Thesis][D]. Lanzhou：Lanzhou University，2017.(in Chinese))
[17]
INOUE A. Formation of clay minerals in hydrothermal environments[M]. Berlin，Heidelberg：Springer，1995：268-329.
[1]
王 驹，郭永海，陈伟明，等. 我国高放废物地质处置选址研究进展[C]// 高放废物地质处置研究进展——核工业北京地质研究院论文集. [S. l.]：[s. n.]，2004：17-21.(WANG Ju，GUO Yonghai，CHEN Weiming，et al. Progress of geological disposal of high-level waste in China[C]// Progress of geological disposal of high-level waste——Proceedings of Beijing Research Institute of Uranium Geology. [S. l.]：[s. n.]，2004：17-21.(in Chinese))
[3]
张虎元，童艳梅，贾全全. 强碱性溶液扩散对高庙子膨润土的化学腐蚀[J]. 岩石力学与工程学报，2020，39(1)：166-176.(ZHANG Huyuan，TONG Yanmei，JIA Quanquan. Corrosion of GMZ bentonite by diffusion of strong alkaline solution[J]. Chinese Journal of Rock Mechanics and Engineering，2020，39(1)：166-176.(in Chinese))
[6]
陈 宝，张会新，陈 萍. 碱溶液对GMZ膨润土膨胀性和渗透性的影响[J]. 中南大学学报：自然科学版，2013，44(2)：294-299.(CHEN Bao，ZHANG Huixin，CHEN Ping. Performance alteration of compacted GMZ bentonite submitted to hyper-alkaline solution[J]. Journal of Central South University：Science and Technology，2013，44(2)：294-299.(in Chinese))
[11]
项国圣，方 圆，徐永福. 阳离子交换对高庙子钠基膨润土膨胀性能的影响[J]. 浙江大学学报：工学版，2017，51(5)：931-936. (XIANG Guosheng，FANG Yuan，XU Yongfu. Swelling characteristics of GMZ01 bentonite affected by cation exchange reaction[J]. Journal of Zhejiang University：Engineering Science，2017，51(5)：931-936.(in Chinese))
[13]
ANH H N，AHN H，JO H Y，et al. Effect of alkaline solutions on bentonite properties[J]. Environmental Earth Sciences，2017，76(11)：374.
[16]
SAWAGUCHI T，TSUKADA M，YAMAGUCHI T，et al. Effects of OH− activity and temperature on the dissolution rate of compacted montmorillonite under highly alkaline conditions[J]. Clay Minerals，2018，51(2)：267-278.
[5]
KARNLAND O，OLSSON S，NILSSON U，et al. Experimentally determined swelling pressures and geochemical interactions of compacted Wyoming bentonite with highly alkaline solutions[J]. Physics and Chemistry of the Earth Parts A/b/c，2007，32(1/7)：275-286.
[15]
WANG Q，CUI Y J，TANG A M，et al. Long-term effect of water chemistry on the swelling pressure of a bentonite-based material[J]. Applied Clay Science，2014，87(1)：157-162.
[2]
张虎元，张国超，余荣光，等. 混合型缓冲砌块膨胀性的空间分布及其各向异性[J]. 岩石力学与工程学报，2019，38(增2)：3 469-3 480. (ZHANG Huyuan，ZHANG Guochao，YU Rongguang，et al. Spatial distribution and anisotropy in swell of compacted bentonite-sand block for HLW buffer barrier[J]. Chinese Journal of Rock Mechanics and Engineering，2019，38(Supp.2)：3 469-3 480.(in Chinese))
[12]
XIANG G S，YE W M，LV L Y. Swelling characteristics of bentonite after long-term dissolution in alkaline solution[J]. Clay Minerals，2019，54(4)：1-18.
[4]
ROMERO E，VILLAR M V，LLORET A. Thermo-hydro-mechanical behavior of two heavily overconsolidated clays[J]. Engineering Geology，2005，81(3)：255-268.
[14]
CHEN Y G，DONG X X，ZHANG X D，et al. Combined thermal and saline effects on the swelling pressure of densely compacted GMZ bentonite[J]. Applied Clay Science，2018，166(DEC.)：318-326.
[10]
ALAWAJI H A. Swell and compressibility characteristics of sand-bentonite mixtures inundated with liquids[J]. Applied Clay Science，1999，15(3/4)：411-430.
[8]
ALAWAJI H A. Swell and compressibility characteristics of sand-bentonite mixtures inundated with liquids[J]. Applied Clay Science，1999，15(3/4)：411-430.
2024, Vol. 43 
