This paper describes the results of subsidence monitoring and back analysis of the tunnel respons... more This paper describes the results of subsidence monitoring and back analysis of the tunnel response along the first section of the Metro Torino Line 1. During excavation, surface settlements were monitored by means of surface levelling and the state of strain/stress in the segmental lining was measured at a number of cross sections. The paper is to gain insights into the ground behaviour analysed by numerical modelling. The aim is to assess the soil deformability and strength parameters as compared to the design values and to predict the stress-strain response in a representative cross section. This paper is concerned with the analysis of ground movements due to tunnelling at a number of monitoring stations during excavation of the Metro Torino Line 1, in a sand and gravel deposit, with presence of the water table. Consideration is given to the transverse and longitudinal settlement trough above and ahead of the advancing tunnel face. The aim is to gain insights into both the ground response and the geotechnical properties, as compared with design predictions and to analyse the interaction between the tunnel and an underground car park in the near vicinity.
Recent innovations in yield-control support systems allow to increase the rate of advance when tu... more Recent innovations in yield-control support systems allow to increase the rate of advance when tunneling in difficult conditions is associated with severely squeezing rock. Such systems which imply the insertion in the lining of highly deformable concrete elements are being adopted successfully in tunneling projects using conventional excavation methods. The Saint Martin access adit excavated in a Carboniferous Formation along the Base Tunnel of the Lyon-Turin rail line ispresented as a case study. Numerical analyses are discussed to compare the results of computed and measured performance of a typical monitored section and to find out possible optimizations of the support system adopted.
The paper deals with the mechanical behaviour of "bimrock" (block in matrix rock), char... more The paper deals with the mechanical behaviour of "bimrock" (block in matrix rock), characterized by a heterogeneous structure, constituted by rock blocks included in a small-grained, well-cemented material (matrix) with lower mechanical characteristics. The bimrock is a very peculiar material that may give rise to serious problems in engineering applications. To properly model this kind of problems it is necessary to suitably characterize the bimrock. In order to contribute to the understanding of the bimrock mechanical behaviour and to individuate strength and deformability laws suitable for the bimrock as an equivalent continuum, as the problem is clearly three-dimensional, 3D numerical analyses have been carried out by using the finite element method implemented in the Adina code. Uniaxial and triaxial compression tests on bimrock laboratory samples are simulated. Different volumetric proportions of the blocks are considered. The numerical results show the influence of ...
This paper deals with full face excavation of large size tunnels in rock masses of very poor qual... more This paper deals with full face excavation of large size tunnels in rock masses of very poor quality which exhibit squeezing behaviour. Time dependence is accounted for explicitly by using constitutive models which have been validated with reference to laboratory testing and in situ performance monitoring. The case study of the Saint Martin La Porte access adit (Lyon-Turin Base Tunnel)
ABSTRACT Recent innovations in yield-control support systems allow to increase the rate of advanc... more ABSTRACT Recent innovations in yield-control support systems allow to increase the rate of advance when tunnelling in difficult conditions is associated with severely squeezing rock. Such systems which imply the insertion in the lining of highly deformable concrete elements are being adopted successfully in tunnelling projects using conventional excavation methods. The Saint Martin access adit excavated in a Carboniferous Formation along the Base Tunnel of the Lyon-Turin rail line is presented as a case study. Numerical analyses are discussed to compare the results of computed and measured performance of a typical monitored section and to find out possible optimizations of the support system adopted.
ABSTRACT This paper describes a study undertaken to derive hazard scenarios for the excavation of... more ABSTRACT This paper describes a study undertaken to derive hazard scenarios for the excavation of the Kishanganga hydroelectric project headrace tunnel, Kashmir, India. The tunnel is to be driven in poor rock mass conditions (meta-sandstones, meta-siltstones and shales) with expected squeezing behaviour under average to high overburden. The excavation is to be carried out using a double shield universal tunnel boring machine (TBM), with concurrent installation of a segmental lining (SL). The highly variable rock mass conditions and the limited data available, due to difficulty of access to the site, required a detailed preliminary study of the most relevant critical factors such as tunnel overburden, in situ state of stress and rock mass properties. Increasing levels of detail were adopted once the significant hazard scenarios for TBM jamming or overloading of the SL in short- and longterm conditions were outlined. The scenarios were first derived by simplified design methods with the rock mass represented as an elasto-plastic continuum. Subsequently, and following the results of laboratory tests on representative samples, numerical modelling studies were performed with the rock mass being modelled as an elasto-visco-plastic continuum.
ABSTRACT This paper presents the monitoring data collected over a period of five years from Janua... more ABSTRACT This paper presents the monitoring data collected over a period of five years from January 2006 to December 2010, during which the Saint Martin La Porte access adit of the Lyon–Turin Base Tunnel was excavated through a Carboniferous Formation, a highly heterogeneous, overstressed and in cases anisotropic rock mass exhibiting a squeezing behaviour. The interest of these data stems from the information which became available along a significant tunnel length in the same rock mass, where a novel excavation and support method was adopted with highly deformable elements inserted in the shotcrete lining which allowed for controlled deformation, rate of deformation and stress in the rock mass and in the supports. A description of the geological and geomechanical conditions met and of the tunnel response in different cross sections is given in terms of developed convergences, rates of convergence, strain distributions around the tunnel and ahead of the face, including the state of stress in the supports. In conclusion an attempt is made to characterise the Carboniferous Formation in terms of the extent of squeezing and in view of the future excavation of the Base Tunnel.
ABSTRACT The Saint Martin La Porte Tunnel, located in South Eastern France near the Italian borde... more ABSTRACT The Saint Martin La Porte Tunnel, located in South Eastern France near the Italian border is one of the access tunnels (together with La Praz and Modane) to the TGV tunnel currently under construction that will connect Lyon and Turin. The excavation of this tunnel through squeezing rock required the adoption of an innovative yield-control support system, assisted by comprehensive performance monitoing and advanced modelling studies. This technical note describes the investigations performed along the tunnnel between chainage 1229 and 1325 m in order to determine the state of stress in the concrete lining. A cast in place lining was chosen in an attempt to stop the large convergences, which occurred in a section where the yield-control system was not yet used. The laboratory tests performed for the cgaracterisation of the mechanical bahaviour of the concrete, the in situ stress relief tets in the lining and simplified numerical modelling are presented.
This paper describes the results of subsidence monitoring and back analysis of the tunnel respons... more This paper describes the results of subsidence monitoring and back analysis of the tunnel response along the first section of the Metro Torino Line 1. During excavation, surface settlements were monitored by means of surface levelling and the state of strain/stress in the segmental lining was measured at a number of cross sections. The paper is to gain insights into the ground behaviour analysed by numerical modelling. The aim is to assess the soil deformability and strength parameters as compared to the design values and to predict the stress-strain response in a representative cross section. This paper is concerned with the analysis of ground movements due to tunnelling at a number of monitoring stations during excavation of the Metro Torino Line 1, in a sand and gravel deposit, with presence of the water table. Consideration is given to the transverse and longitudinal settlement trough above and ahead of the advancing tunnel face. The aim is to gain insights into both the ground response and the geotechnical properties, as compared with design predictions and to analyse the interaction between the tunnel and an underground car park in the near vicinity.
Recent innovations in yield-control support systems allow to increase the rate of advance when tu... more Recent innovations in yield-control support systems allow to increase the rate of advance when tunneling in difficult conditions is associated with severely squeezing rock. Such systems which imply the insertion in the lining of highly deformable concrete elements are being adopted successfully in tunneling projects using conventional excavation methods. The Saint Martin access adit excavated in a Carboniferous Formation along the Base Tunnel of the Lyon-Turin rail line ispresented as a case study. Numerical analyses are discussed to compare the results of computed and measured performance of a typical monitored section and to find out possible optimizations of the support system adopted.
The paper deals with the mechanical behaviour of "bimrock" (block in matrix rock), char... more The paper deals with the mechanical behaviour of "bimrock" (block in matrix rock), characterized by a heterogeneous structure, constituted by rock blocks included in a small-grained, well-cemented material (matrix) with lower mechanical characteristics. The bimrock is a very peculiar material that may give rise to serious problems in engineering applications. To properly model this kind of problems it is necessary to suitably characterize the bimrock. In order to contribute to the understanding of the bimrock mechanical behaviour and to individuate strength and deformability laws suitable for the bimrock as an equivalent continuum, as the problem is clearly three-dimensional, 3D numerical analyses have been carried out by using the finite element method implemented in the Adina code. Uniaxial and triaxial compression tests on bimrock laboratory samples are simulated. Different volumetric proportions of the blocks are considered. The numerical results show the influence of ...
This paper deals with full face excavation of large size tunnels in rock masses of very poor qual... more This paper deals with full face excavation of large size tunnels in rock masses of very poor quality which exhibit squeezing behaviour. Time dependence is accounted for explicitly by using constitutive models which have been validated with reference to laboratory testing and in situ performance monitoring. The case study of the Saint Martin La Porte access adit (Lyon-Turin Base Tunnel)
ABSTRACT Recent innovations in yield-control support systems allow to increase the rate of advanc... more ABSTRACT Recent innovations in yield-control support systems allow to increase the rate of advance when tunnelling in difficult conditions is associated with severely squeezing rock. Such systems which imply the insertion in the lining of highly deformable concrete elements are being adopted successfully in tunnelling projects using conventional excavation methods. The Saint Martin access adit excavated in a Carboniferous Formation along the Base Tunnel of the Lyon-Turin rail line is presented as a case study. Numerical analyses are discussed to compare the results of computed and measured performance of a typical monitored section and to find out possible optimizations of the support system adopted.
ABSTRACT This paper describes a study undertaken to derive hazard scenarios for the excavation of... more ABSTRACT This paper describes a study undertaken to derive hazard scenarios for the excavation of the Kishanganga hydroelectric project headrace tunnel, Kashmir, India. The tunnel is to be driven in poor rock mass conditions (meta-sandstones, meta-siltstones and shales) with expected squeezing behaviour under average to high overburden. The excavation is to be carried out using a double shield universal tunnel boring machine (TBM), with concurrent installation of a segmental lining (SL). The highly variable rock mass conditions and the limited data available, due to difficulty of access to the site, required a detailed preliminary study of the most relevant critical factors such as tunnel overburden, in situ state of stress and rock mass properties. Increasing levels of detail were adopted once the significant hazard scenarios for TBM jamming or overloading of the SL in short- and longterm conditions were outlined. The scenarios were first derived by simplified design methods with the rock mass represented as an elasto-plastic continuum. Subsequently, and following the results of laboratory tests on representative samples, numerical modelling studies were performed with the rock mass being modelled as an elasto-visco-plastic continuum.
ABSTRACT This paper presents the monitoring data collected over a period of five years from Janua... more ABSTRACT This paper presents the monitoring data collected over a period of five years from January 2006 to December 2010, during which the Saint Martin La Porte access adit of the Lyon–Turin Base Tunnel was excavated through a Carboniferous Formation, a highly heterogeneous, overstressed and in cases anisotropic rock mass exhibiting a squeezing behaviour. The interest of these data stems from the information which became available along a significant tunnel length in the same rock mass, where a novel excavation and support method was adopted with highly deformable elements inserted in the shotcrete lining which allowed for controlled deformation, rate of deformation and stress in the rock mass and in the supports. A description of the geological and geomechanical conditions met and of the tunnel response in different cross sections is given in terms of developed convergences, rates of convergence, strain distributions around the tunnel and ahead of the face, including the state of stress in the supports. In conclusion an attempt is made to characterise the Carboniferous Formation in terms of the extent of squeezing and in view of the future excavation of the Base Tunnel.
ABSTRACT The Saint Martin La Porte Tunnel, located in South Eastern France near the Italian borde... more ABSTRACT The Saint Martin La Porte Tunnel, located in South Eastern France near the Italian border is one of the access tunnels (together with La Praz and Modane) to the TGV tunnel currently under construction that will connect Lyon and Turin. The excavation of this tunnel through squeezing rock required the adoption of an innovative yield-control support system, assisted by comprehensive performance monitoing and advanced modelling studies. This technical note describes the investigations performed along the tunnnel between chainage 1229 and 1325 m in order to determine the state of stress in the concrete lining. A cast in place lining was chosen in an attempt to stop the large convergences, which occurred in a section where the yield-control system was not yet used. The laboratory tests performed for the cgaracterisation of the mechanical bahaviour of the concrete, the in situ stress relief tets in the lining and simplified numerical modelling are presented.
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