Lin-Yong Cui, Wei-Min Ye, Qiong Wang, Yong-Gui Chen, Yu-Jun Cui
{"title":"刚性边界条件下饱和 GMZ 膨润土的连续气体突破行为研究","authors":"Lin-Yong Cui, Wei-Min Ye, Qiong Wang, Yong-Gui Chen, Yu-Jun Cui","doi":"10.1007/s11440-024-02391-z","DOIUrl":null,"url":null,"abstract":"<div><p>Understanding impacts of gas breakthrough processes on the sealing ability of the bentonite buffer/backfill materials is crucial for the safety evaluation of the nuclear waste geological repository. In this work, the residual capillary pressure method was utilized to conduct successive gas breakthrough tests on compacted Gaomiaozi bentonite specimens. During each gas breakthrough test, the upstream gas pressure was increased in a step-by-step way until the gas breakthrough was recorded. Water permeability tests were performed before each gas breakthrough to ensure that the bentonite specimen was fully saturated. Finally, after experienced five successive gas breakthrough processes, the bentonite specimen was submitted for the mercury intrusion porosimetry (MIP) test. For comparison, four other parallel specimens that experienced one to four gas breakthroughs, respectively, were also submitted for the MIP tests to examine the possible damage of the bentonite matrix resulted from gas breakthrough processes. Results show that, during the first three successive gas breakthrough tests, the gas breakthrough pressure and the snap-off pressure decreased rapidly from 4.46 to 3.66 MPa and from 0.51 to 0.26 MPa, respectively. An exponential decrease in the maximum effective gas permeability from 3.75 × 10<sup>–18</sup> to 3.17 × 10<sup>–19</sup> m<sup>2</sup> with gas breakthroughs experienced could also be observed. On contrary, both of the saturated water permeability and the pore size distribution show little difference as compared to its initial value. These results indicate that gas breakthrough process could induce a degradation of gas-tightness capacity of the bentonite specimen. Meanwhile, the gas injection pressure was reset to zero before conducting the water permeability test. Reducing the gas pressure will induce a contraction in the radius of the gas pathway, even leading to complete closure. Consequently, the water permeability and the pore size distribution remained almost unchanged.</p></div>","PeriodicalId":49308,"journal":{"name":"Acta Geotechnica","volume":"19 10","pages":"6773 - 6786"},"PeriodicalIF":5.6000,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Investigation on successive gas breakthroughs behavior of saturated GMZ bentonite under rigid boundary conditions\",\"authors\":\"Lin-Yong Cui, Wei-Min Ye, Qiong Wang, Yong-Gui Chen, Yu-Jun Cui\",\"doi\":\"10.1007/s11440-024-02391-z\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>Understanding impacts of gas breakthrough processes on the sealing ability of the bentonite buffer/backfill materials is crucial for the safety evaluation of the nuclear waste geological repository. In this work, the residual capillary pressure method was utilized to conduct successive gas breakthrough tests on compacted Gaomiaozi bentonite specimens. During each gas breakthrough test, the upstream gas pressure was increased in a step-by-step way until the gas breakthrough was recorded. Water permeability tests were performed before each gas breakthrough to ensure that the bentonite specimen was fully saturated. Finally, after experienced five successive gas breakthrough processes, the bentonite specimen was submitted for the mercury intrusion porosimetry (MIP) test. For comparison, four other parallel specimens that experienced one to four gas breakthroughs, respectively, were also submitted for the MIP tests to examine the possible damage of the bentonite matrix resulted from gas breakthrough processes. Results show that, during the first three successive gas breakthrough tests, the gas breakthrough pressure and the snap-off pressure decreased rapidly from 4.46 to 3.66 MPa and from 0.51 to 0.26 MPa, respectively. An exponential decrease in the maximum effective gas permeability from 3.75 × 10<sup>–18</sup> to 3.17 × 10<sup>–19</sup> m<sup>2</sup> with gas breakthroughs experienced could also be observed. On contrary, both of the saturated water permeability and the pore size distribution show little difference as compared to its initial value. These results indicate that gas breakthrough process could induce a degradation of gas-tightness capacity of the bentonite specimen. Meanwhile, the gas injection pressure was reset to zero before conducting the water permeability test. Reducing the gas pressure will induce a contraction in the radius of the gas pathway, even leading to complete closure. Consequently, the water permeability and the pore size distribution remained almost unchanged.</p></div>\",\"PeriodicalId\":49308,\"journal\":{\"name\":\"Acta Geotechnica\",\"volume\":\"19 10\",\"pages\":\"6773 - 6786\"},\"PeriodicalIF\":5.6000,\"publicationDate\":\"2024-08-28\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Acta Geotechnica\",\"FirstCategoryId\":\"5\",\"ListUrlMain\":\"https://link.springer.com/article/10.1007/s11440-024-02391-z\",\"RegionNum\":1,\"RegionCategory\":\"工程技术\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"ENGINEERING, GEOLOGICAL\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Acta Geotechnica","FirstCategoryId":"5","ListUrlMain":"https://link.springer.com/article/10.1007/s11440-024-02391-z","RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"ENGINEERING, GEOLOGICAL","Score":null,"Total":0}
Investigation on successive gas breakthroughs behavior of saturated GMZ bentonite under rigid boundary conditions
Understanding impacts of gas breakthrough processes on the sealing ability of the bentonite buffer/backfill materials is crucial for the safety evaluation of the nuclear waste geological repository. In this work, the residual capillary pressure method was utilized to conduct successive gas breakthrough tests on compacted Gaomiaozi bentonite specimens. During each gas breakthrough test, the upstream gas pressure was increased in a step-by-step way until the gas breakthrough was recorded. Water permeability tests were performed before each gas breakthrough to ensure that the bentonite specimen was fully saturated. Finally, after experienced five successive gas breakthrough processes, the bentonite specimen was submitted for the mercury intrusion porosimetry (MIP) test. For comparison, four other parallel specimens that experienced one to four gas breakthroughs, respectively, were also submitted for the MIP tests to examine the possible damage of the bentonite matrix resulted from gas breakthrough processes. Results show that, during the first three successive gas breakthrough tests, the gas breakthrough pressure and the snap-off pressure decreased rapidly from 4.46 to 3.66 MPa and from 0.51 to 0.26 MPa, respectively. An exponential decrease in the maximum effective gas permeability from 3.75 × 10–18 to 3.17 × 10–19 m2 with gas breakthroughs experienced could also be observed. On contrary, both of the saturated water permeability and the pore size distribution show little difference as compared to its initial value. These results indicate that gas breakthrough process could induce a degradation of gas-tightness capacity of the bentonite specimen. Meanwhile, the gas injection pressure was reset to zero before conducting the water permeability test. Reducing the gas pressure will induce a contraction in the radius of the gas pathway, even leading to complete closure. Consequently, the water permeability and the pore size distribution remained almost unchanged.
期刊介绍:
Acta Geotechnica is an international journal devoted to the publication and dissemination of basic and applied research in geoengineering – an interdisciplinary field dealing with geomaterials such as soils and rocks. Coverage emphasizes the interplay between geomechanical models and their engineering applications. The journal presents original research papers on fundamental concepts in geomechanics and their novel applications in geoengineering based on experimental, analytical and/or numerical approaches. The main purpose of the journal is to foster understanding of the fundamental mechanisms behind the phenomena and processes in geomaterials, from kilometer-scale problems as they occur in geoscience, and down to the nano-scale, with their potential impact on geoengineering. The journal strives to report and archive progress in the field in a timely manner, presenting research papers, review articles, short notes and letters to the editors.