Shengming Hu, Jianglin Gao, Lei Huang, Zhichao Zhang, Cheng Huang, Sheng Zhang, Fang Cheng, Zhihui Yuan, Yu Su
A widespread case of discontinuity shearing is among the local shallow rock blocks sliding along non-planer, rough, non-anchored discontinuities, which is characterized by initial normal load in addition to free subsequent change in local normal load/stiffness, provoked by shear dilatancy (INL). The existing direct shear apparatuses of rock discontinuities fitted for those cases are rare, and it is lack of understanding the shear behaviors of discontinuities under such INL boundary conditions. Here, we develop an INL direct shear tester of discontinuities for shear strength. This tester takes advantage of the direct shear test apparatus modified after the YZ-5 model without a servo-controlled system to permit the accomplishment of those boundary conditions. Shear behaviors of unfilled discontinuities and infilled ones under INL boundary conditions are investigated. Moreover, the possible influence of clay content on those shear behavior of infilled discontinuities is clarified. The developed tester made it possible to test the shear performance of the local shallow rock blocks sliding along non-planer, rough, non-anchored discontinuities. This work contributed to a limited body of researches on the shear behaviors of discontinuities under those INL boundary conditions. Limitations of this work are also revealed.
{"title":"Developing an initial normal-loading, subsequent passive changes in local normal load/stiffness-allowable direct shear tester of discontinuities and investigating the shear behaviors of discontinuities","authors":"Shengming Hu, Jianglin Gao, Lei Huang, Zhichao Zhang, Cheng Huang, Sheng Zhang, Fang Cheng, Zhihui Yuan, Yu Su","doi":"10.1144/qjegh2023-087","DOIUrl":"https://doi.org/10.1144/qjegh2023-087","url":null,"abstract":"A widespread case of discontinuity shearing is among the local shallow rock blocks sliding along non-planer, rough, non-anchored discontinuities, which is characterized by initial normal load in addition to free subsequent change in local normal load/stiffness, provoked by shear dilatancy (INL). The existing direct shear apparatuses of rock discontinuities fitted for those cases are rare, and it is lack of understanding the shear behaviors of discontinuities under such INL boundary conditions. Here, we develop an INL direct shear tester of discontinuities for shear strength. This tester takes advantage of the direct shear test apparatus modified after the YZ-5 model without a servo-controlled system to permit the accomplishment of those boundary conditions. Shear behaviors of unfilled discontinuities and infilled ones under INL boundary conditions are investigated. Moreover, the possible influence of clay content on those shear behavior of infilled discontinuities is clarified. The developed tester made it possible to test the shear performance of the local shallow rock blocks sliding along non-planer, rough, non-anchored discontinuities. This work contributed to a limited body of researches on the shear behaviors of discontinuities under those INL boundary conditions. Limitations of this work are also revealed.","PeriodicalId":20937,"journal":{"name":"Quarterly Journal of Engineering Geology and Hydrogeology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2024-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140999168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Sarıçay Dam project in southwestern Türkiye integrates advanced geotechnical evaluation methods for building dams in areas with challenging geology and seismic activity. This study foregrounds an in-depth analysis of deformation modulus, the efficacy of consolidation grouting, and shear strength parameters. It addresses critical issues such as encountering faults during construction and their mitigation, with the 'observational approach' being adopted to inform strategies and solutions and/or any modifications to these, including any design aspects. The appropriate selection of the deformation modulus and understanding its enhancement through consolidation grouting remain long-standing issues in geotechnical engineering. The comprehensive analyses of the deformation modulus revealed that certain empirical equations yield results comparable to those from in-situ tests, although some may significantly overestimate; hence, correlating these tests with geophysical methods is crucial for accurate evaluation. Moreover, the deformation modulus results, derived from both rock pressuremeter and dilatometer tests on similarly characterized rock masses, displayed a notable comparability, despite the inherent scatter attributed to rock masses' heterogeneity and anisotropy. The findings revealed that consolidation grouting, despite its minimal effect on increasing the deformation modulus (4% to 18%), plays a role in reinforcing the foundation by filling joints and fractures. The research experiences and outcomes on this project will contribute to the knowledge base for future dam projects.
{"title":"Sarıçay Dam: A Case Study on In-Depth Seismic Evaluation, Deformation Modulus, and Key Geotechnical Parameters","authors":"Sarper Demirdogen, Sefa Yildirim","doi":"10.1144/qjegh2024-002","DOIUrl":"https://doi.org/10.1144/qjegh2024-002","url":null,"abstract":"The Sarıçay Dam project in southwestern Türkiye integrates advanced geotechnical evaluation methods for building dams in areas with challenging geology and seismic activity. This study foregrounds an in-depth analysis of deformation modulus, the efficacy of consolidation grouting, and shear strength parameters. It addresses critical issues such as encountering faults during construction and their mitigation, with the 'observational approach' being adopted to inform strategies and solutions and/or any modifications to these, including any design aspects. The appropriate selection of the deformation modulus and understanding its enhancement through consolidation grouting remain long-standing issues in geotechnical engineering. The comprehensive analyses of the deformation modulus revealed that certain empirical equations yield results comparable to those from in-situ tests, although some may significantly overestimate; hence, correlating these tests with geophysical methods is crucial for accurate evaluation. Moreover, the deformation modulus results, derived from both rock pressuremeter and dilatometer tests on similarly characterized rock masses, displayed a notable comparability, despite the inherent scatter attributed to rock masses' heterogeneity and anisotropy. The findings revealed that consolidation grouting, despite its minimal effect on increasing the deformation modulus (4% to 18%), plays a role in reinforcing the foundation by filling joints and fractures. The research experiences and outcomes on this project will contribute to the knowledge base for future dam projects.","PeriodicalId":20937,"journal":{"name":"Quarterly Journal of Engineering Geology and Hydrogeology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2024-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140664036","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Guang-Tao Yu, Hong-Yuan Fu, Qianhong Gao, Ling Zeng, Jia-Jun Li
Silty mudstone is highly susceptible to the influence of hot and humid environments, leading to the deterioration of its mechanical properties presenting a geohazard and even resulting in geological disasters. Accurately characterizing the effects of bedding and water-rock interaction on the mechanical behavior of silty mudstone is a crucial prerequisite for the protection and reinforcement of silty mudstone slopes. To this end, uniaxial compression tests and Brazilian splitting tests were conducted to examine the mechanical properties of bedded silty mudstone. Based on the test results, the effects of bedding angle and soaking time on mechanical properties such as tensile strength, uniaxial compressive strength and elastic modulus of bedded silty mudstone were revealed. The test results showed that the tensile strength increased exponentially with increasing bedding angle. The observed split failure patterns of bedded silty mudstone encompassed splitting-pulling damage, shear damage, and splitting damage. The uniaxial compressive strength of silty mudstone exhibited a U-shaped variation with an increase in bedding angle. The specimen with a bedding angle of 45° had the lowest uniaxial compressive strength at 7.64 MPa. Furthermore, the elastic modulus of silty mudstone was positively correlated with the bedding angle. The failure patterns of bedded silty mudstone under uniaxial compression included splitting-tension damage, shear-slip damage, and splitting-shear damage. The saturated tensile strength, uniaxial compressive strength and elastic modulus of bedded silty mudstone exhibited an exponential decrease with increasing soaking time. The test data confirmed the applicability of the Jaeger equation to the uniaxial compressive strength of bedded silty mudstone. Subsequently, a modified Hoek-Brown failure criterion was derived by combining fracture mechanics theory and test results and introducing a softening factor. The parameters A , D and m in the above failure criterion decreased exponentially with increasing soaking time and a empirical Hooke-Brown failure criterion considering the soaking time was established. Compared with previous theoretical models, this model is more adaptable to the actual engineering situation, which results in more accurate calculations.
淤泥质泥岩极易受到湿热环境的影响，导致其机械性能下降，造成地质灾害，甚至引发地质灾害。准确描述垫层和水岩相互作用对淤泥质泥岩力学行为的影响，是保护和加固淤泥质泥岩边坡的重要前提。为此，我们进行了单轴压缩试验和巴西劈裂试验，以研究垫层淤泥质泥岩的力学特性。根据试验结果，揭示了垫层角度和浸泡时间对垫层淤泥质泥岩拉伸强度、单轴压缩强度和弹性模量等力学性能的影响。试验结果表明，抗拉强度随着铺层角度的增大呈指数增长。观察到的层状淤泥质泥岩劈裂破坏形态包括劈裂-拉拔破坏、剪切破坏和劈裂破坏。淤泥质泥岩的单轴抗压强度随着铺层角度的增加呈 U 型变化。垫层角为 45°的试样单轴抗压强度最低，为 7.64 兆帕。此外，淤泥质泥岩的弹性模量与铺层角度呈正相关。淤泥质泥岩在单轴压缩下的破坏模式包括劈裂-拉伸破坏、剪切-滑动破坏和劈裂-剪切破坏。随着浸泡时间的增加，层状粉砂质泥岩的饱和抗拉强度、单轴抗压强度和弹性模量呈指数下降。试验数据证实了 Jaeger 方程适用于层状粉砂质泥岩的单轴抗压强度。随后，结合断裂力学理论和测试结果，并引入软化因子，得出了修正的 Hoek-Brown 失效准则。上述破坏准则中的参数 A、D 和 m 随浸泡时间的增加呈指数下降，因此建立了考虑浸泡时间的经验胡克-布朗破坏准则。与以往的理论模型相比，该模型更适应实际工程情况，计算结果更准确。
{"title":"Influences of Bedding Angle and Soaking Time on the Mechanical Behaviour of Silty Mudstone: Laboratory Testing and Theoretical Modelling","authors":"Guang-Tao Yu, Hong-Yuan Fu, Qianhong Gao, Ling Zeng, Jia-Jun Li","doi":"10.1144/qjegh2023-126","DOIUrl":"https://doi.org/10.1144/qjegh2023-126","url":null,"abstract":"\u0000 Silty mudstone is highly susceptible to the influence of hot and humid environments, leading to the deterioration of its mechanical properties presenting a geohazard and even resulting in geological disasters. Accurately characterizing the effects of bedding and water-rock interaction on the mechanical behavior of silty mudstone is a crucial prerequisite for the protection and reinforcement of silty mudstone slopes. To this end, uniaxial compression tests and Brazilian splitting tests were conducted to examine the mechanical properties of bedded silty mudstone. Based on the test results, the effects of bedding angle and soaking time on mechanical properties such as tensile strength, uniaxial compressive strength and elastic modulus of bedded silty mudstone were revealed. The test results showed that the tensile strength increased exponentially with increasing bedding angle. The observed split failure patterns of bedded silty mudstone encompassed splitting-pulling damage, shear damage, and splitting damage. The uniaxial compressive strength of silty mudstone exhibited a U-shaped variation with an increase in bedding angle. The specimen with a bedding angle of 45° had the lowest uniaxial compressive strength at 7.64 MPa. Furthermore, the elastic modulus of silty mudstone was positively correlated with the bedding angle. The failure patterns of bedded silty mudstone under uniaxial compression included splitting-tension damage, shear-slip damage, and splitting-shear damage. The saturated tensile strength, uniaxial compressive strength and elastic modulus of bedded silty mudstone exhibited an exponential decrease with increasing soaking time. The test data confirmed the applicability of the Jaeger equation to the uniaxial compressive strength of bedded silty mudstone. Subsequently, a modified Hoek-Brown failure criterion was derived by combining fracture mechanics theory and test results and introducing a softening factor. The parameters\u0000 A\u0000 ,\u0000 D\u0000 and\u0000 m\u0000 in the above failure criterion decreased exponentially with increasing soaking time and a empirical Hooke-Brown failure criterion considering the soaking time was established. Compared with previous theoretical models, this model is more adaptable to the actual engineering situation, which results in more accurate calculations.\u0000","PeriodicalId":20937,"journal":{"name":"Quarterly Journal of Engineering Geology and Hydrogeology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140674545","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper focuses on the risk of water inrush from the old goaf water of the upper coal group to the first mining face of the lower coal group under the condition of fully mechanized caving mining. Data from the 2101 working face of the No.15 coal seam in Wulihou Coal Mine were used to calculate the height of the water-conducting fracture zone on the first mining working face and the floor failure depth in the overlying No.5 coal seam. An engineering geological model was developed, considering the lithological combination of the upper and lower coal groups, as well as the geological and hydrogeological conditions. Numerical simulations were conducted to analyze the deformation and failure characteristics of the roof and floor after dual-seam mining. The results revealed a floor damage depth of 12 m and a water-conducting fracture zone height of 109 m. Field monitoring data confirmed that after mining the 2101 working face, there was no water inrush risk from the overlying old goaf water into the No.15 coal seam through the water-conducting fracture zone. The research results provide a reference for preventing water inrush accidents in similar fully mechanized top coal caving mining under the old goaf water.
{"title":"Study on water inrush risk of overlying old goaf water in fully mechanized caving mining of lower coal group","authors":"Zhilong Yang, Shuyun Zhu, Yingzhou Chen","doi":"10.1144/qjegh2023-064","DOIUrl":"https://doi.org/10.1144/qjegh2023-064","url":null,"abstract":"This paper focuses on the risk of water inrush from the old goaf water of the upper coal group to the first mining face of the lower coal group under the condition of fully mechanized caving mining. Data from the 2101 working face of the No.15 coal seam in Wulihou Coal Mine were used to calculate the height of the water-conducting fracture zone on the first mining working face and the floor failure depth in the overlying No.5 coal seam. An engineering geological model was developed, considering the lithological combination of the upper and lower coal groups, as well as the geological and hydrogeological conditions. Numerical simulations were conducted to analyze the deformation and failure characteristics of the roof and floor after dual-seam mining. The results revealed a floor damage depth of 12 m and a water-conducting fracture zone height of 109 m. Field monitoring data confirmed that after mining the 2101 working face, there was no water inrush risk from the overlying old goaf water into the No.15 coal seam through the water-conducting fracture zone. The research results provide a reference for preventing water inrush accidents in similar fully mechanized top coal caving mining under the old goaf water.","PeriodicalId":20937,"journal":{"name":"Quarterly Journal of Engineering Geology and Hydrogeology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140672294","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Affected by fault structure and in-situ stress, the heterogeneity of permeability of surrounding rock is universal. Treating it as a fixed value will reduce the prediction accuracy of water inflow and structural head. In view of this problem, considering the coupling effect of ground stress and fault structure, the permeability of surrounding rock is regarded as a spatially discrete type, a plane one-dimensional seepage calculation model in the vertical section is constructed, and the phreatic surface drop curve equation is established. Using Taylor's formula and series expansion theorem, the equation can be reduced to the expression of the falling curve when the permeability of the surrounding rock is homogeneous. Based on Darcy's law and the law of conservation of fluid mass, the calculation formula for tunnel water inflow and external water pressure of the structure was derived. And verified through ongoing construction projects. Research shows that the calculation error of water inflow can be reduced from 23.1% to 7.5% when considering the influence of ground stress and fault structure on the permeability of surrounding rock, and the calculation error of water head borne by the supporting structure can be reduced from 43.8% to 30%, which improves the prediction accuracy. Thematic collection: This article is part of the Climate change and resilience in Engineering Geology and Hydrogeology collection available at: https://www.lyellcollection.org/topic/collections/climate-change-and-resilience-in-engineering-geology-and-hydrogeology
{"title":"Analysis of the impact of uneven permeability of surrounding rock caused by the coupling effect of ground stresses and fault structure on sudden water inrush in tunnels","authors":"Pengtao An, Fan Lin, Haixin Wen, Fu Helin","doi":"10.1144/qjegh2023-151","DOIUrl":"https://doi.org/10.1144/qjegh2023-151","url":null,"abstract":"Affected by fault structure and in-situ stress, the heterogeneity of permeability of surrounding rock is universal. Treating it as a fixed value will reduce the prediction accuracy of water inflow and structural head. In view of this problem, considering the coupling effect of ground stress and fault structure, the permeability of surrounding rock is regarded as a spatially discrete type, a plane one-dimensional seepage calculation model in the vertical section is constructed, and the phreatic surface drop curve equation is established. Using Taylor's formula and series expansion theorem, the equation can be reduced to the expression of the falling curve when the permeability of the surrounding rock is homogeneous. Based on Darcy's law and the law of conservation of fluid mass, the calculation formula for tunnel water inflow and external water pressure of the structure was derived. And verified through ongoing construction projects. Research shows that the calculation error of water inflow can be reduced from 23.1% to 7.5% when considering the influence of ground stress and fault structure on the permeability of surrounding rock, and the calculation error of water head borne by the supporting structure can be reduced from 43.8% to 30%, which improves the prediction accuracy.\u0000 \u0000 Thematic collection:\u0000 This article is part of the Climate change and resilience in Engineering Geology and Hydrogeology collection available at:\u0000 https://www.lyellcollection.org/topic/collections/climate-change-and-resilience-in-engineering-geology-and-hydrogeology\u0000","PeriodicalId":20937,"journal":{"name":"Quarterly Journal of Engineering Geology and Hydrogeology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140672939","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
To the reservoirs of the oil wells with no cored data, predicting porosity from wireline logs and core samples is an effective approach. Integration of conventional well logs and core samples to predict porosity with large accuracy is a particularly challenging work due to complex logging responses of tight sandstone. Therefore, a novel predicting workflow based on linear interpolation algorithm (LIA) is described to estimate porosity from well logs in the present study. Based on core reposition, porosity correction under overburden pressure, core-log data matching, and calculation of shale content, two multi regression formulas to estimate porosity values are obtained by nearest neighbor algorithm and linear interpolation algorithm respectively. The formulas are applied to the tight sandstone in Chang 9 member of Yanchang Formation in northeast Wuqi Oilfield, Ordos Basin. The comparison results indicate that the porosity predicted from the formula obtained by LIA is in better agreement with the measured porosity, showing a better prediction effect. The application example demonstrates that the LIA formula is of good applicability for the core porosity prediction in the study region. This methodology can further be applied for porosity prediction in other oil regions that have similarities in geological background.
对于没有岩心数据的油井储层来说，通过有线测井和岩心样本预测孔隙度是一种有效的方法。由于致密砂岩的测井响应非常复杂，整合常规测井曲线和岩心样本以高精度预测孔隙度是一项特别具有挑战性的工作。因此，本研究介绍了一种基于线性插值算法（LIA）的新型预测工作流程，用于根据测井曲线估算孔隙度。基于岩心重新定位、覆盖层压力下的孔隙度校正、岩心-测井曲线数据匹配以及页岩含量计算，通过近邻算法和线性插值算法分别获得了两个估算孔隙度值的多元回归公式。将这些公式应用于鄂尔多斯盆地吴旗油田东北部延长地层长 9 层致密砂岩。对比结果表明，用 LIA 算法预测的孔隙度与实测孔隙度比较一致，显示出较好的预测效果。应用实例表明，LIA 公式在研究区域的岩心孔隙度预测中具有良好的适用性。该方法还可进一步应用于地质背景相似的其他油区的孔隙度预测。
{"title":"Integration of conventional well logs and core samples to predict porosity of","authors":"Xia Wang, Guomin Fu, Bojiang Fan, Shuai Wang, Luping Feng, Cheng Peng","doi":"10.1144/qjegh2023-042","DOIUrl":"https://doi.org/10.1144/qjegh2023-042","url":null,"abstract":"To the reservoirs of the oil wells with no cored data, predicting porosity from wireline logs and core samples is an effective approach. Integration of conventional well logs and core samples to predict porosity with large accuracy is a particularly challenging work due to complex logging responses of tight sandstone. Therefore, a novel predicting workflow based on linear interpolation algorithm (LIA) is described to estimate porosity from well logs in the present study. Based on core reposition, porosity correction under overburden pressure, core-log data matching, and calculation of shale content, two multi regression formulas to estimate porosity values are obtained by nearest neighbor algorithm and linear interpolation algorithm respectively. The formulas are applied to the tight sandstone in Chang 9 member of Yanchang Formation in northeast Wuqi Oilfield, Ordos Basin. The comparison results indicate that the porosity predicted from the formula obtained by LIA is in better agreement with the measured porosity, showing a better prediction effect. The application example demonstrates that the LIA formula is of good applicability for the core porosity prediction in the study region. This methodology can further be applied for porosity prediction in other oil regions that have similarities in geological background.","PeriodicalId":20937,"journal":{"name":"Quarterly Journal of Engineering Geology and Hydrogeology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2024-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140682395","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper reviews the current state-of-the-art in relation to geotechnical design in unsorted till deposits, commonly called Boulder clays by engineers or diamictons by geologists, generally taking the topics discussed by Prof. Eamon Hanrahan in his seminal work on Irish tills of 1977. These topics include the permeability, stiffness, and consolidation characteristics of these deposits, together with their undrained and drained behaviour. The geological background to the deposition of these tills is discussed and the available information on the presence of interglacial soils around the country is presented. Where possible, the practical experience from working with these deposits is compared with predictions made from field or laboratory test results, for example, in settlement assessment of foundations, slope stability and in earthworks. Whilst most of Ireland is covered with stony Boulder clays, which is the main topic of the paper, the geotechnical parameters of a fine grained till encountered on the east coast, known as Irish Sea till or colloquially as Macamore Clay, are discussed and the implications of this on slope stability is investigated.
{"title":"The 1st Hanrahan Lecture: Geotechnical properties of Irish glacial and interglacial soils","authors":"Eric R Farrell","doi":"10.1144/qjegh2023-148","DOIUrl":"https://doi.org/10.1144/qjegh2023-148","url":null,"abstract":"This paper reviews the current state-of-the-art in relation to geotechnical design in unsorted till deposits, commonly called Boulder clays by engineers or diamictons by geologists, generally taking the topics discussed by Prof. Eamon Hanrahan in his seminal work on Irish tills of 1977. These topics include the permeability, stiffness, and consolidation characteristics of these deposits, together with their undrained and drained behaviour. The geological background to the deposition of these tills is discussed and the available information on the presence of interglacial soils around the country is presented. Where possible, the practical experience from working with these deposits is compared with predictions made from field or laboratory test results, for example, in settlement assessment of foundations, slope stability and in earthworks.\u0000 Whilst most of Ireland is covered with stony Boulder clays, which is the main topic of the paper, the geotechnical parameters of a fine grained till encountered on the east coast, known as Irish Sea till or colloquially as Macamore Clay, are discussed and the implications of this on slope stability is investigated.","PeriodicalId":20937,"journal":{"name":"Quarterly Journal of Engineering Geology and Hydrogeology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2024-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140694538","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Gang Yang, Tianbin Li, Hao Tang, Dongwei Xing, Yao Hu, Shisen Li
The intactness of rock masses is a fundamental parameter in classifying surrounding rocks. Due to limitations imposed by the extent of tunnel face outcrops, the assessment of rock mass intactness necessitates the manual extraction of the positions, orientations, and spacing of joints/fissures. To mitigate the labor-intensive nature of this process, in this paper, deep learning is employed to develop an integrated method for the automated extraction of joints/fissures and the quantitative analysis of rock mass intactness. We introduce an image preprocessing method based on multiscale histogram equalization to obtain high-contrast, low-noise images. The DeepIntactness model, which incorporates the strategy of curriculum learning to utilize a large number of unlabeled tunnel rock images for model training is introduced for the extraction of joints/fissures. Following the extraction of joints/fissures, a multiline center statistic method based on the rock mass block index method is employed to evaluate the intactness of the most vulnerable part of the tunnel face. By applying this approach to an engineering structure, its capacity to automatically extract and quantitatively evaluate the engineering properties of the surrounding rock mass intactness is demonstrated. Hence, this method provides a novel approach to evaluating the tunnel surrounding rock intactness using two-dimensional images. Supplementary material: https://doi.org/10.6084/m9.figshare.c.7154677
{"title":"Evaluation Method for the Intactness of the Tunnel Face Surrounding Rock based on Tunnel Face Images","authors":"Gang Yang, Tianbin Li, Hao Tang, Dongwei Xing, Yao Hu, Shisen Li","doi":"10.1144/qjegh2024-018","DOIUrl":"https://doi.org/10.1144/qjegh2024-018","url":null,"abstract":"The intactness of rock masses is a fundamental parameter in classifying surrounding rocks. Due to limitations imposed by the extent of tunnel face outcrops, the assessment of rock mass intactness necessitates the manual extraction of the positions, orientations, and spacing of joints/fissures. To mitigate the labor-intensive nature of this process, in this paper, deep learning is employed to develop an integrated method for the automated extraction of joints/fissures and the quantitative analysis of rock mass intactness. We introduce an image preprocessing method based on multiscale histogram equalization to obtain high-contrast, low-noise images. The DeepIntactness model, which incorporates the strategy of curriculum learning to utilize a large number of unlabeled tunnel rock images for model training is introduced for the extraction of joints/fissures. Following the extraction of joints/fissures, a multiline center statistic method based on the rock mass block index method is employed to evaluate the intactness of the most vulnerable part of the tunnel face. By applying this approach to an engineering structure, its capacity to automatically extract and quantitatively evaluate the engineering properties of the surrounding rock mass intactness is demonstrated. Hence, this method provides a novel approach to evaluating the tunnel surrounding rock intactness using two-dimensional images.\u0000 \u0000 Supplementary material:\u0000 https://doi.org/10.6084/m9.figshare.c.7154677\u0000","PeriodicalId":20937,"journal":{"name":"Quarterly Journal of Engineering Geology and Hydrogeology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2024-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140704101","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hao Li, Qixiang Yan, Hong Zhang, Lizhou Wu, J. Zhou
Tunnels exhibit obvious continuous deformation during excavation and operation. This behavior is closely associated with the time-dependent behavior of rocks, which is induced by groundwater level fluctuation and prolonged periodic rainfall infiltration. This paper proposes a rheological model consisting of a Hooke elastomer, Kelvin body, and novel plastic element in series (called the HKP model) to describe the creep response of rocks considering the characteristics of dry–wet cycles. First, dry–wet cycle creep tests were carried out to investigate the time-dependent behavior, that is, the creep behavior of sandstone. Then, the creep equation of the viscoelastic–plastic model was derived, and the damage coefficients under the effect of dry–wet cycles and time were obtained. Finally, the HKP model was established to investigate the continuous deformation during tunnel excavation. The results reveal that dry–wet cycles have obvious effects on the physical properties and creep behavior of sandstone. The creep behavior of sandstone undergoes three stages, namely, the decaying, steady, and accelerated stages, which can be reasonably described by the proposed HKP model. The proposed model can accurately predict the creep behavior of tunnel due to excavation in practice, for this particular project. Thus, the HKP model can help in establishing tunnel maintenance strategies to ensure long–term safety.
{"title":"Viscoelastic–plastic rheological model and its application to tunnels","authors":"Hao Li, Qixiang Yan, Hong Zhang, Lizhou Wu, J. Zhou","doi":"10.1144/qjegh2023-081","DOIUrl":"https://doi.org/10.1144/qjegh2023-081","url":null,"abstract":"Tunnels exhibit obvious continuous deformation during excavation and operation. This behavior is closely associated with the time-dependent behavior of rocks, which is induced by groundwater level fluctuation and prolonged periodic rainfall infiltration. This paper proposes a rheological model consisting of a Hooke elastomer, Kelvin body, and novel plastic element in series (called the HKP model) to describe the creep response of rocks considering the characteristics of dry–wet cycles. First, dry–wet cycle creep tests were carried out to investigate the time-dependent behavior, that is, the creep behavior of sandstone. Then, the creep equation of the viscoelastic–plastic model was derived, and the damage coefficients under the effect of dry–wet cycles and time were obtained. Finally, the HKP model was established to investigate the continuous deformation during tunnel excavation. The results reveal that dry–wet cycles have obvious effects on the physical properties and creep behavior of sandstone. The creep behavior of sandstone undergoes three stages, namely, the decaying, steady, and accelerated stages, which can be reasonably described by the proposed HKP model. The proposed model can accurately predict the creep behavior of tunnel due to excavation in practice, for this particular project. Thus, the HKP model can help in establishing tunnel maintenance strategies to ensure long–term safety.","PeriodicalId":20937,"journal":{"name":"Quarterly Journal of Engineering Geology and Hydrogeology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2024-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140720410","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Diego D. Barra, Felipe A. Villalobos, Diego A. Vasco, Javier Fumeron
Renewable energy has become a relevant alternative to solve energy and environmental problems worldwide. The characterisation of the geothermal resource is fundamental for an efficient and sustainable extraction of heat. In this study, thermal conductivity λ , volumetric heat capacity C and thermal diffusivity α of two soils from Chile, namely Bío Bío sand and Maicillo residual soil, are analysed. Bío Bío sand is a uniform and clean sand which is mainly constituted by basaltic particles, whereas Maicillo is a silty and clayey sand with a high content of quartz. Samples were tested with a thermal needle probe at varying water content and density. Measurements to obtain λ , C and α were undertaken. These results allowed the study of patterns and relationships between geotechnical and heat transfer parameters. It was found that dry soil conditions led to the lowest values of λ , whereas saturated soil conditions led to the highest values. Moreover, Maicillo has higher capabilities to transfer heat than Bío Bío sand, which can reach up to 50% in λ for dense soil and saturated conditions. This is due to its quarzitic and clayey mineralogy and non-uniform grain size distribution. The results from this research represent an important contribution for industrial applications.
{"title":"Variation of thermal properties with water content and density of residual and basaltic sands from Chile","authors":"Diego D. Barra, Felipe A. Villalobos, Diego A. Vasco, Javier Fumeron","doi":"10.1144/qjegh2023-137","DOIUrl":"https://doi.org/10.1144/qjegh2023-137","url":null,"abstract":"\u0000 Renewable energy has become a relevant alternative to solve energy and environmental problems worldwide. The characterisation of the geothermal resource is fundamental for an efficient and sustainable extraction of heat. In this study, thermal conductivity\u0000 \u0000 \u0000 λ\u0000 \u0000 \u0000 , volumetric heat capacity\u0000 C\u0000 and thermal diffusivity\u0000 \u0000 \u0000 α\u0000 \u0000 \u0000 of two soils from Chile, namely Bío Bío sand and Maicillo residual soil, are analysed. Bío Bío sand is a uniform and clean sand which is mainly constituted by basaltic particles, whereas Maicillo is a silty and clayey sand with a high content of quartz. Samples were tested with a thermal needle probe at varying water content and density. Measurements to obtain\u0000 \u0000 \u0000 λ\u0000 \u0000 \u0000 ,\u0000 C\u0000 and\u0000 \u0000 \u0000 α\u0000 \u0000 \u0000 were undertaken. These results allowed the study of patterns and relationships between geotechnical and heat transfer parameters. It was found that dry soil conditions led to the lowest values of\u0000 \u0000 \u0000 λ\u0000 \u0000 \u0000 , whereas saturated soil conditions led to the highest values. Moreover, Maicillo has higher capabilities to transfer heat than Bío Bío sand, which can reach up to 50% in\u0000 \u0000 \u0000 λ\u0000 \u0000 \u0000 for dense soil and saturated conditions. This is due to its quarzitic and clayey mineralogy and non-uniform grain size distribution. The results from this research represent an important contribution for industrial applications.\u0000","PeriodicalId":20937,"journal":{"name":"Quarterly Journal of Engineering Geology and Hydrogeology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2024-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140376254","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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