A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Geotechnical and Earth Resources Engineering

Thesis (M. Eng.) - Asian Institute of Technology, 2023

In metropolitan areas, it is crucial to use ground stabilization and improvement techniques when carrying out soft ground tunneling. This involves various aspects such as designing, treating the ground, construction techniques, material properties, for launching and arrival of large-diameter tunnel boring machines (TBM{u2019}s) from underground stations and shafts, all while dealing with different geological conditions. To ensure the stability of the soil and control groundwater, it is necessary to improve the soil before the TBM{u2019}s breakthrough. In many underground projects, jet grouting is commonly used as an improvement technique to strengthen the soft ground, maintain TBM stability, and prevent groundwater leakage while maintaining a safe margin. Due to the complexities of the site conditions, the dimensions of the construction may be different from the original design. This study aims to evaluate the actual construction dimensions and compare them with the design dimensions. Additionally, a parametric study was conducted using numerical analysis software to investigate the effects of modifying certain jet grouting design parameters on soil stability and seepage issues when the diaphragm wall is opened for TBMs launching and arrival in Thailand. This paper discusses the results of the comparison between actual construction dimensions with calculated design guideline dimensions. The study revealed that most construction dimensions exceed the design dimensions, and the strength of the jet grouting mixture plays a significant role in determining the size of the jet grouting blocks. Moreover, the outcomes of the parametric studies proposes a trend for enhancing the design dimensions of jet grouting in future projects in Thailand.