A reliable geological model plays a fundamental role in the efficiency and safety of mountain tunnel construction.However,regional models based on limited survey data represent macroscopic geological environments but ...A reliable geological model plays a fundamental role in the efficiency and safety of mountain tunnel construction.However,regional models based on limited survey data represent macroscopic geological environments but not detailed internal geological characteristics,especially at tunnel portals with complex geological conditions.This paper presents a comprehensive methodological framework for refined modeling of the tunnel surrounding rock and subsequent mechanics analysis,with a particular focus on natural space distortion of hard-soft rock interfaces at tunnel portals.The progressive prediction of geological structures is developed considering multi-source data derived from the tunnel survey and excavation stages.To improve the accuracy of the models,a novel modeling method is proposed to integrate multi-source and multi-scale data based on data extraction and potential field interpolation.Finally,a regional-scale model and an engineering-scale model are built,providing a clear insight into geological phenomena and supporting numerical calculation.In addition,the proposed framework is applied to a case study,the Long-tou mountain tunnel project in Guangzhou,China,where the dominant rock type is granite.The results show that the data integration and modeling methods effectively improve model structure refinement.The improved model’s calculation deviation is reduced by about 10%to 20%in the mechanical analysis.This study contributes to revealing the complex geological environment with singular interfaces and promoting the safety and performance of mountain tunneling.展开更多
Considering that the particular geometric shape of a quasi-rectangular shield,the grout flowing law and its motion process are more complicated than those of a conventional circular shield.To interpret the grouting me...Considering that the particular geometric shape of a quasi-rectangular shield,the grout flowing law and its motion process are more complicated than those of a conventional circular shield.To interpret the grouting mechanical ehaviour in the special-shape shield tail void,the filling and diffusion mechanism of synchronous grouting was analysed.The grout flowing is separated into two independent motion processes,which contains a circumferential filling and a longitudinal diffusion.The theoretical model of the grout pressure spatial distribution was derived based on the principle of fluid mechanics.Then,the pressure distributions in the two directions were obtained using a case study and compared with the field measured data to verify the validation of the model.Although the overall spatial pattern of grout pressure distribution on the tunnel profile show a change trend dominated by the self-weight effect mostly,its local fluctuation characteristics is very abnormal relative to that of a circular shield tunnel.Moreover,the important factors in the model were analysed,including the grout material parameters,the grouting construction parameters,and some geometry parameters.The results show that the pressure loss along this way is positively correlated with the grout flow velocity and is sensitive to the shear yield stress of the grout.The pressure loss along the circumferential direction is the most sensitive to the thickness of the ring cake,and the value range suitable for the model should be 0.02-0.03 m.The pressure loss along the longitudinal diffusion direction is the most sensitive to the size of the tail void.The research results can provide a theoretical basis for the control of special-shape shield construction.展开更多
Quasi-rectangular shield tunneling is a cutting-edge trenchless method for constructing metro tunnels with double tubes,owing to its advantages in saving underground space and reducing ground disturbance.However,the c...Quasi-rectangular shield tunneling is a cutting-edge trenchless method for constructing metro tunnels with double tubes,owing to its advantages in saving underground space and reducing ground disturbance.However,the conventional quasi-rectangular shield tunneling method is not applicable when constructing a tunnel without a center pillar,such as a scissor crossover section of a metro line.Therefore,the O-0 tunneling method,which combines the quasirectangular shield and pipe jacking methods,was investigated in this study to solve the aforementioned construction challenges.This study presents a case study of the Sijiqing Station of the Hangzhou Metro Line 9 in China,in which the O-0 method was first proposed and applied.Key techniques such as switching between two types of tunneling modes and the tunneling process control in complex construction environments were investigated.The results demonstrated that the O-0 method can address the technical challenges presented by the post-transition line with a high curvature and a scissors crossover line.In addition,the adoption of the 0-0 method ensured that the transformation between shield tunneling and pipe jacking was safe and efficient.The ground settlement monitoring results demonstrated that the disturbance to the surrounding environment can be limited to a safe level.This case study contributes to the construction technology for a metro tunnel containing both post-transition lines with a small turning radius and a scissors crossover line.A practical construction experience and theoretical guidance were provided in this study,which are of significance for both the industry and academia.展开更多
基金supported by the National Natural Science Foundation of China,China(Grant No.41827807)the“Social Development Project of Science and Technology Commission of Shanghai Municipality,China(Grant No.21DZ1201105)”+1 种基金“The Fundamental Research Funds for the Central Universities,China(Grant No.21D111320)”the“Systematic Project of Guangxi Key Laboratory of Disaster Prevention and Engineering Safety,China(Grant No.2022ZDK018)”.
文摘A reliable geological model plays a fundamental role in the efficiency and safety of mountain tunnel construction.However,regional models based on limited survey data represent macroscopic geological environments but not detailed internal geological characteristics,especially at tunnel portals with complex geological conditions.This paper presents a comprehensive methodological framework for refined modeling of the tunnel surrounding rock and subsequent mechanics analysis,with a particular focus on natural space distortion of hard-soft rock interfaces at tunnel portals.The progressive prediction of geological structures is developed considering multi-source data derived from the tunnel survey and excavation stages.To improve the accuracy of the models,a novel modeling method is proposed to integrate multi-source and multi-scale data based on data extraction and potential field interpolation.Finally,a regional-scale model and an engineering-scale model are built,providing a clear insight into geological phenomena and supporting numerical calculation.In addition,the proposed framework is applied to a case study,the Long-tou mountain tunnel project in Guangzhou,China,where the dominant rock type is granite.The results show that the data integration and modeling methods effectively improve model structure refinement.The improved model’s calculation deviation is reduced by about 10%to 20%in the mechanical analysis.This study contributes to revealing the complex geological environment with singular interfaces and promoting the safety and performance of mountain tunneling.
基金sponsored by the Shanghai Rising-Star Program of China(Grant No.18QB1403800)supported by the Fundamental Research Funds for the Central Universities(Grant No.21D111320).
文摘Considering that the particular geometric shape of a quasi-rectangular shield,the grout flowing law and its motion process are more complicated than those of a conventional circular shield.To interpret the grouting mechanical ehaviour in the special-shape shield tail void,the filling and diffusion mechanism of synchronous grouting was analysed.The grout flowing is separated into two independent motion processes,which contains a circumferential filling and a longitudinal diffusion.The theoretical model of the grout pressure spatial distribution was derived based on the principle of fluid mechanics.Then,the pressure distributions in the two directions were obtained using a case study and compared with the field measured data to verify the validation of the model.Although the overall spatial pattern of grout pressure distribution on the tunnel profile show a change trend dominated by the self-weight effect mostly,its local fluctuation characteristics is very abnormal relative to that of a circular shield tunnel.Moreover,the important factors in the model were analysed,including the grout material parameters,the grouting construction parameters,and some geometry parameters.The results show that the pressure loss along this way is positively correlated with the grout flow velocity and is sensitive to the shear yield stress of the grout.The pressure loss along the circumferential direction is the most sensitive to the thickness of the ring cake,and the value range suitable for the model should be 0.02-0.03 m.The pressure loss along the longitudinal diffusion direction is the most sensitive to the size of the tail void.The research results can provide a theoretical basis for the control of special-shape shield construction.
基金theSSocial Development Project of Science and Technology Commission of Shanghai Municipality(No.21DZ1201105)the Fundamental Research Funds for the Central Universities(No.21D111320)the National Natural Science Foundation of China(Grant No.42201489).
文摘Quasi-rectangular shield tunneling is a cutting-edge trenchless method for constructing metro tunnels with double tubes,owing to its advantages in saving underground space and reducing ground disturbance.However,the conventional quasi-rectangular shield tunneling method is not applicable when constructing a tunnel without a center pillar,such as a scissor crossover section of a metro line.Therefore,the O-0 tunneling method,which combines the quasirectangular shield and pipe jacking methods,was investigated in this study to solve the aforementioned construction challenges.This study presents a case study of the Sijiqing Station of the Hangzhou Metro Line 9 in China,in which the O-0 method was first proposed and applied.Key techniques such as switching between two types of tunneling modes and the tunneling process control in complex construction environments were investigated.The results demonstrated that the O-0 method can address the technical challenges presented by the post-transition line with a high curvature and a scissors crossover line.In addition,the adoption of the 0-0 method ensured that the transformation between shield tunneling and pipe jacking was safe and efficient.The ground settlement monitoring results demonstrated that the disturbance to the surrounding environment can be limited to a safe level.This case study contributes to the construction technology for a metro tunnel containing both post-transition lines with a small turning radius and a scissors crossover line.A practical construction experience and theoretical guidance were provided in this study,which are of significance for both the industry and academia.
