ABSTRACT
Constant urbanisation calls for new transportation solutions occupying the least possible city area. Tunnelling in this context requires processing significant amount of data regarding the geotechnical condition and the neighbouring context. To meet the growing demand of mechanised tunnelling in dense areas, automated, flexible, and fast calculation algorithms are needed to optimize processing time and improve the design precision.
Aiming to cope with these requirements, a digital design approach has been developed to create a georeferenced database, including the intrinsic vulnerability of neighbouring structures, geological conditions, project alignment, and TBM characteristics.
This approach permits to discretise the alignment, associate a calculation algorithm to evaluate the TBM confinement pressure at each desired point, taking into account the surrounding conditions which have a direct influence on the TBM parameters.
The optimal pressure is iteratively obtained to meet deformation thresholds defined by the acceptable damage classes of adjacent structures. Expected ground displacements are determined along the alignment, ahead of the face and above the tunnel crown, resulting in a 3D settlement trough. During TBM operation, thanks to database updating, the pressure gradient is automatically adjusted following the on-site condition.
This paper presents a novel method to define the intrinsic vulnerability state of neighbouring structures, create a georeferenced database to model existing structures (buildings, utilities, infrastructures, etc.), calculate the volume loss and consequently the TBM face pressure which assures the integrity of the surroundings.
