Geotechnical research has been yearning for revolutionary innovations that could bring breakthroughs to conventional practices,especially at a time when energy efficiency and environmental sustainability are of unprec...Geotechnical research has been yearning for revolutionary innovations that could bring breakthroughs to conventional practices,especially at a time when energy efficiency and environmental sustainability are of unprecedented importance in the field.Recently,exciting opportunities emerged utilising microorganisms,the ubiquitous soil dwellers,to provide solutions to many geotechnical problems,prompting the development of the new,multidisciplinary subject of biogeotechnics.Research interest has been centred on the use of microbially induced carbonate precipitation(MICP)to improve the engineering properties of soils.The present work aims to comprehensively review the progress of more than a decade of research on the application of MICP in soil strengthening.Through elucidation of underlying mechanisms,compilation and interpretation of experimental findings,and in-depth discussion on pivotal aspects,with reference made to key published studies,a holistic picture of the state of the art of MICP-based soil strengthening is drawn.Current knowledge gaps are identified,and suggestions for future research are given,along with the opportunities and challenges that lie ahead of practically implementing this technique in real-world geotechnical applications.展开更多
Transport structures built throughout the period from 1960 to 1980 in permafrost regions based on the principle of permafrost preservation are subject to deformations.In many cases,the reason is a gradual change in te...Transport structures built throughout the period from 1960 to 1980 in permafrost regions based on the principle of permafrost preservation are subject to deformations.In many cases,the reason is a gradual change in temperature and their subgrade condition within the active zone due to the structures'technogenic impact.Design solutions for the fifty-year-old structures fail to ensure in all cases their reliable operation at the present time.The greatest danger to the reliable operation of railway lines in cold regions is uneven deformations of bridges,which are barrier places.Therefore,the solution to this problem is urgent especially due to the necessity of increase carrying capacity.The purpose of this study is to increase reliability of bridge operation in cold regions through strengthening the subgrade by reinforcement with injection of solidifying solutions.The problem of uneven deformations due to permafrost degradation is considered using the example of a railway bridge located in the northern line of the Krasnoyarsk railway.Deformations of the bridge abutments began immediately after the construction was completed and the bridge was open for traffic-since 1977.Permafrost degradation was developing more actively straight under the abutments due to higher thermal conductivity of the piles concrete.Notably,thawing intensity of frozen soils under the bridge abutments is uneven due to its orientation to the cardinal points.The analysis of archive materials and results of the geodetic survey made it possible to systematize the features of augmenting deformations of each abutment over time.The engineering-geological survey with drilling wells near the abutments ensured determination of soil characteristics,both in the frozen and thawed states.Thermometric wells were arranged to measure temperatures.The analysis and systematization of the data obtained allowed us to develop geotechnical models for each abutment of the bridge.The peculiarity of these models is allowance for changes in the strength and deformation characteristics of the soil calculated layers depending on changes in temperature and the soil condition.Thus,different calculated geological elements with the corresponding strength and deformation characteristics were identified in the soil layers of the same origin.The analysis of the systematized geodetic data allowed us to confirm adequacy of the developed geotechnical models.Studies carried out using geotechnical models made it possible to predict improvement of physical and mechanical characteristics of the subgrade to prevent further growth deformations of the bridge abutments.The method of reinforcement by injection is proposed.Injecting a solution under pressure leads to strengthening of weakened thawed soils and improving their physical and mechanical properties.This research theoretically substantiates and develops the geotechnical models of the reinforced pier footing of bridge abutments by injection of solidifying solutions.The models take into account the reinforcement parameters and elements for the case in question.The influence of reinforcement on the change in physical and mechanical properties of the soil mass is determined.展开更多
基金supported by the UK Engineering and Physical Sciences Research Council(EPSRC)grant(reference number:EP/S02302X/1)for the University of Cambridge Centre for Doctoral Training in Future Infrastructure and Built Environment.
文摘Geotechnical research has been yearning for revolutionary innovations that could bring breakthroughs to conventional practices,especially at a time when energy efficiency and environmental sustainability are of unprecedented importance in the field.Recently,exciting opportunities emerged utilising microorganisms,the ubiquitous soil dwellers,to provide solutions to many geotechnical problems,prompting the development of the new,multidisciplinary subject of biogeotechnics.Research interest has been centred on the use of microbially induced carbonate precipitation(MICP)to improve the engineering properties of soils.The present work aims to comprehensively review the progress of more than a decade of research on the application of MICP in soil strengthening.Through elucidation of underlying mechanisms,compilation and interpretation of experimental findings,and in-depth discussion on pivotal aspects,with reference made to key published studies,a holistic picture of the state of the art of MICP-based soil strengthening is drawn.Current knowledge gaps are identified,and suggestions for future research are given,along with the opportunities and challenges that lie ahead of practically implementing this technique in real-world geotechnical applications.
文摘Transport structures built throughout the period from 1960 to 1980 in permafrost regions based on the principle of permafrost preservation are subject to deformations.In many cases,the reason is a gradual change in temperature and their subgrade condition within the active zone due to the structures'technogenic impact.Design solutions for the fifty-year-old structures fail to ensure in all cases their reliable operation at the present time.The greatest danger to the reliable operation of railway lines in cold regions is uneven deformations of bridges,which are barrier places.Therefore,the solution to this problem is urgent especially due to the necessity of increase carrying capacity.The purpose of this study is to increase reliability of bridge operation in cold regions through strengthening the subgrade by reinforcement with injection of solidifying solutions.The problem of uneven deformations due to permafrost degradation is considered using the example of a railway bridge located in the northern line of the Krasnoyarsk railway.Deformations of the bridge abutments began immediately after the construction was completed and the bridge was open for traffic-since 1977.Permafrost degradation was developing more actively straight under the abutments due to higher thermal conductivity of the piles concrete.Notably,thawing intensity of frozen soils under the bridge abutments is uneven due to its orientation to the cardinal points.The analysis of archive materials and results of the geodetic survey made it possible to systematize the features of augmenting deformations of each abutment over time.The engineering-geological survey with drilling wells near the abutments ensured determination of soil characteristics,both in the frozen and thawed states.Thermometric wells were arranged to measure temperatures.The analysis and systematization of the data obtained allowed us to develop geotechnical models for each abutment of the bridge.The peculiarity of these models is allowance for changes in the strength and deformation characteristics of the soil calculated layers depending on changes in temperature and the soil condition.Thus,different calculated geological elements with the corresponding strength and deformation characteristics were identified in the soil layers of the same origin.The analysis of the systematized geodetic data allowed us to confirm adequacy of the developed geotechnical models.Studies carried out using geotechnical models made it possible to predict improvement of physical and mechanical characteristics of the subgrade to prevent further growth deformations of the bridge abutments.The method of reinforcement by injection is proposed.Injecting a solution under pressure leads to strengthening of weakened thawed soils and improving their physical and mechanical properties.This research theoretically substantiates and develops the geotechnical models of the reinforced pier footing of bridge abutments by injection of solidifying solutions.The models take into account the reinforcement parameters and elements for the case in question.The influence of reinforcement on the change in physical and mechanical properties of the soil mass is determined.
