This book focuses on the field of geomechanics and shield tunnel engineering, with a particular emphasis on soil conditioning and its critical role in shield tunneling. It outlines the distinct behaviors of conditioned soil different from natural soil utilizing self-designed testing apparatus and innovative calculation methods. The effects of conditioned soil properties on the shield tunneling performance are revealed from numerical analysis and practical applications. Additionally, the optimization frameworks and machine learning-based approaches for soil conditioning are developed for risk prevention strategies in shield tunneling. This book is the first academic monograph dedicated to soil conditioning in earth pressure balance shield tunneling. It is written for senior undergraduates, graduate students, professors, enterprise supervisory engineering staff, and researchers in the field of shield tunneling technology.