Anuradha Khetwal

The usual approach to numerical modeling to predict tunnel response is by determining model input parameters from laboratory and in situ testing of the soil and rock where the tunnel will be built. Usually, however, laboratory and in situ testing are limited in quantity, quality, and scope, leading to many uncertainties in the reliability of input parameters and model predictions.

The present study aims to investigate the physical, petrological, and mechanical properties of ten different types of rocks in the Indian subcontinent, required for the design of structures built in rocks. A comparative assessment is done for the stress-strain response of all the rocks collected under three main categories, e.g., igneous, sedimentary, and metamorphic. The physical properties, e.g., densities and slake durability indices, are determined. The peterological tests are carried out by scanning electron microscope and the X-ray diffraction technique. Mechanical properties, e.g., hardness, uniaxial compressive strength, elastic modulus, and Poisson’s ratio, of the 10 different types of rocks are obtained through static loading at a strain rate of 0.001/s. Lastly, various correlation equations are proposed relating the uniaxial compressive strength, density, elastic modulus, and hardness of the 10 rocks. And the rocks are classified based on the Deere-Miller rock mass classification system.

Tunnel Boring Machine (TBM) is one of the most efficient methods for underground excavation. The estimation of the performance of TBM requires accounting for a large number of factors like geology, machine design and configuration, and operations. Simulation of tunnel activities considering TBM to be a tunneling factory can be a reliable method for estimation of TBM utilization factor. The subsurface geotechnical conditions that control machine penetration rate and muck transportation system are the two most important technical factors affecting the overall performance of the machine in a routine operation. This paper focuses on establishing the impact of geology on the muck transportation system to observe the interdependence between TBM penetration rate and transportation delays. The muck haulage system should be designed to incorporate the changes in the excavation rate in different geology to minimize related delays. The simulations were performed using discrete event simulation software, ARENA, where various tunnel activities were modeled in their relevant sequence with varying geological conditions. The simulation accounts for the number of trains and addition of California switch to examine the impact of the setting on transportation-related delays in various formations.