Based on inspection data,the authors analyze and summarize the main types and distribution characteristics of tunnel structural defects.These defects are classified into three types:surface defects,internal defects,an...Based on inspection data,the authors analyze and summarize the main types and distribution characteristics of tunnel structural defects.These defects are classified into three types:surface defects,internal defects,and defects behind the structure.To address the need for rapid detection of different defect types,the current state of rapid detection technologies and equipment,both domestically and internationally,is systematically reviewed.The research reveals that surface defect detection technologies and equipment have developed rapidly in recent years.Notably,the integration of machine vision and laser scanning technologies have significantly improved detection efficiency and accuracy,achieving crack detection precision of up to 0.1 mm.However,the non-contact rapid detection of internal and behind-the-structure defects remains constrained by hardware limitations,with traditional detection remaining dominant.Nevertheless,phased array radar,ultrasonic,and acoustic vibration detection technologies have become research hotspots in recent years,offering promising directions for detecting these challenging defect types.Additionally,the application of multisensor fusion technology in rapid detection equipment has further enhanced detection capabilities.Devices such as cameras,3D laser scanners,infrared thermal imagers,and radar demonstrate significant advantages in rapid detection.Future research in tunnel inspection should prioritize breakthroughs in rapid detection technologies for internal and behind-the-structure defects.Efforts should also focus on developing multifunctional integrated detection vehicles that can simultaneously inspect both surface and internal structures.Furthermore,progress in fully automated,intelligent systems with precise defect identification and real-time reporting will be essential to significantly improve the efficiency and accuracy of tunnel inspection.展开更多
Accurately predicting the overlying pressure is crucial for determining an appropriate cover depth of underwater box tunnels to avoid the uplifting failure.Based on the project of box jacking crossing the Beijing-Hang...Accurately predicting the overlying pressure is crucial for determining an appropriate cover depth of underwater box tunnels to avoid the uplifting failure.Based on the project of box jacking crossing the Beijing-Hangzhou Grand Canal in Suzhou,the characteristics of overlying pressure variation during tunneling are investigated.The monitoring results reveal that the fluctuation of overlying pressure is weakened during the rapid tunneling process.A modified analytical model for vertical earth pressure is conceived,in which the active and passive limit states for multi-layered soils are both considered.The probable range of overlying pressure obtained by the proposed model is suitable to cover the actual values.The anti-floating behavior of underwater box tunnels for two different working conditions is discussed by calculating the minimum cover depth.Using the calibrated analytical models,a parametric study is conducted to explore the influence of injection pressure,hardened slurry unit weight,soil internal friction angle,soil cohesion,and tunnel geometry.It is found that the injection pressure during the construction process is crucial for determining the necessary cover depth,and the change of box tunnel height makes it easier to trigger the variation of minimum cover depth.展开更多
The deformation instability of surrounding rock and the collapse of rock blocks are two common failure modes observed during the construction of underground caverns.Therefore,a comprehensive safety evaluation method(C...The deformation instability of surrounding rock and the collapse of rock blocks are two common failure modes observed during the construction of underground caverns.Therefore,a comprehensive safety evaluation method(CSEM)of surrounding rock for application during underground cavern construction is presented in this paper.The method can be used to evaluate the deformation stability of surrounding rock and predict the collapse of rock blocks,rapidly.First,a deformation stability prediction and evaluation method(DSPEM)for rock mass is established.It combines the safety evaluation method based on a deformation statistical analysis and an inverse deformation prediction method using measured deformation data of surrounding rock.This approach possesses the unique characteristics of complementary and mutual verification.In addition,a comprehensive early-warning index system(CWIS)for assessing the deformation stability of surrounding rock is presented.It consists of three types of warning indicators and three levels of warning values.The earlywarning values can be adjusted reasonably by the prediction correction method according to the measured displacements.For the collapse of rock blocks controlled by structural surfaces,a rapid prediction method of rock block collapse(RPMBC)based on the block theory is then presented.Finally,combining the DSPEM,RPMBC,and CWIS,the CSEM of surrounding rock for assessing the safety of cavern construction is established.It can provide technical support for decision making on the safety of surrounding rock during the construction of underground caverns.展开更多
Exploitation and utilization of urban underground space resources is gaining increasing attention in cities’sustainable development.Due to the attributes of fragility and irreversibility,urban underground space resou...Exploitation and utilization of urban underground space resources is gaining increasing attention in cities’sustainable development.Due to the attributes of fragility and irreversibility,urban underground space resources can be extremely vulnerable to damage and it is often difficult in restoring their original state once damaged.Therefore,scientific and reasonable evaluation of urban underground space resources is of vital importance in urban planning and development.This paper first describes the content and methods for the evaluation of urban underground space resources,and introduces the digitalization technologies to handle the problems of strong subjectivity,low efficiency and rough precision encountered when using traditional evaluation tools.Then,the related concepts and main technologies for digitalization were demonstrated and an intelligent GIS-based engineering geology system was built.Based on the drilling information in Changzhou City,stratum standardization and 3D modeling of strata,underground structures and pipelines were conducted in the built intelligent system.Finally,with the help of spatial overlay analysis in the GIS-based platform and a combination of other digitalization technologies,the urban underground space resources of Changzhou City were evaluated.Maps of geological suitability were produced,which provide scientific guidance and reference for the exploitation and planning of urban underground space resources in Changzhou City.In addition,site selection for key projects was conducted based on the evaluation results using this platform.展开更多
文摘Based on inspection data,the authors analyze and summarize the main types and distribution characteristics of tunnel structural defects.These defects are classified into three types:surface defects,internal defects,and defects behind the structure.To address the need for rapid detection of different defect types,the current state of rapid detection technologies and equipment,both domestically and internationally,is systematically reviewed.The research reveals that surface defect detection technologies and equipment have developed rapidly in recent years.Notably,the integration of machine vision and laser scanning technologies have significantly improved detection efficiency and accuracy,achieving crack detection precision of up to 0.1 mm.However,the non-contact rapid detection of internal and behind-the-structure defects remains constrained by hardware limitations,with traditional detection remaining dominant.Nevertheless,phased array radar,ultrasonic,and acoustic vibration detection technologies have become research hotspots in recent years,offering promising directions for detecting these challenging defect types.Additionally,the application of multisensor fusion technology in rapid detection equipment has further enhanced detection capabilities.Devices such as cameras,3D laser scanners,infrared thermal imagers,and radar demonstrate significant advantages in rapid detection.Future research in tunnel inspection should prioritize breakthroughs in rapid detection technologies for internal and behind-the-structure defects.Efforts should also focus on developing multifunctional integrated detection vehicles that can simultaneously inspect both surface and internal structures.Furthermore,progress in fully automated,intelligent systems with precise defect identification and real-time reporting will be essential to significantly improve the efficiency and accuracy of tunnel inspection.
基金supported by the Natural Science Foundation of Jiangsu Province of China (Grant Nos.BK20230500 and BK20210721)the Young Talent Fund of Association for Science and Technology in Shaanxi,China (Grant No.20240722).
文摘Accurately predicting the overlying pressure is crucial for determining an appropriate cover depth of underwater box tunnels to avoid the uplifting failure.Based on the project of box jacking crossing the Beijing-Hangzhou Grand Canal in Suzhou,the characteristics of overlying pressure variation during tunneling are investigated.The monitoring results reveal that the fluctuation of overlying pressure is weakened during the rapid tunneling process.A modified analytical model for vertical earth pressure is conceived,in which the active and passive limit states for multi-layered soils are both considered.The probable range of overlying pressure obtained by the proposed model is suitable to cover the actual values.The anti-floating behavior of underwater box tunnels for two different working conditions is discussed by calculating the minimum cover depth.Using the calibrated analytical models,a parametric study is conducted to explore the influence of injection pressure,hardened slurry unit weight,soil internal friction angle,soil cohesion,and tunnel geometry.It is found that the injection pressure during the construction process is crucial for determining the necessary cover depth,and the change of box tunnel height makes it easier to trigger the variation of minimum cover depth.
基金The research presented in this paper was supported by the National Nature Science Foundation of China(Grant Nos.51739006 and U1765204).
文摘The deformation instability of surrounding rock and the collapse of rock blocks are two common failure modes observed during the construction of underground caverns.Therefore,a comprehensive safety evaluation method(CSEM)of surrounding rock for application during underground cavern construction is presented in this paper.The method can be used to evaluate the deformation stability of surrounding rock and predict the collapse of rock blocks,rapidly.First,a deformation stability prediction and evaluation method(DSPEM)for rock mass is established.It combines the safety evaluation method based on a deformation statistical analysis and an inverse deformation prediction method using measured deformation data of surrounding rock.This approach possesses the unique characteristics of complementary and mutual verification.In addition,a comprehensive early-warning index system(CWIS)for assessing the deformation stability of surrounding rock is presented.It consists of three types of warning indicators and three levels of warning values.The earlywarning values can be adjusted reasonably by the prediction correction method according to the measured displacements.For the collapse of rock blocks controlled by structural surfaces,a rapid prediction method of rock block collapse(RPMBC)based on the block theory is then presented.Finally,combining the DSPEM,RPMBC,and CWIS,the CSEM of surrounding rock for assessing the safety of cavern construction is established.It can provide technical support for decision making on the safety of surrounding rock during the construction of underground caverns.
基金This study is supported by China National Engineering Institute’s Consulting Project(grant No.2015-XZ-16-01)National Basic Research Program of China(973 Program)(grant No.2011CB013800).We gratefully acknowledge Changzhou Urban Planning Bureau,Changzhou City Planning and Design Institute,Shanghai Tongyan Civil Engineering Technology Co.,Ltd.and Nanjing University for their valuable cooperation in performing the evaluation of urban underground space resources in Changzhou City.
文摘Exploitation and utilization of urban underground space resources is gaining increasing attention in cities’sustainable development.Due to the attributes of fragility and irreversibility,urban underground space resources can be extremely vulnerable to damage and it is often difficult in restoring their original state once damaged.Therefore,scientific and reasonable evaluation of urban underground space resources is of vital importance in urban planning and development.This paper first describes the content and methods for the evaluation of urban underground space resources,and introduces the digitalization technologies to handle the problems of strong subjectivity,low efficiency and rough precision encountered when using traditional evaluation tools.Then,the related concepts and main technologies for digitalization were demonstrated and an intelligent GIS-based engineering geology system was built.Based on the drilling information in Changzhou City,stratum standardization and 3D modeling of strata,underground structures and pipelines were conducted in the built intelligent system.Finally,with the help of spatial overlay analysis in the GIS-based platform and a combination of other digitalization technologies,the urban underground space resources of Changzhou City were evaluated.Maps of geological suitability were produced,which provide scientific guidance and reference for the exploitation and planning of urban underground space resources in Changzhou City.In addition,site selection for key projects was conducted based on the evaluation results using this platform.
