Abstract: A multifield coupling mechanism model that simultaneously considers materials, structure, environment, and construction factors is adopted to quantitatively evaluate the cracking risks of sidewall concrete and prevent leakages caused by the shrinkage cracking of working shaft sidewall concrete and the uncompacted combination between sidewalls and a ring frame beam. Then, anticracking control indices are proposed. second, Investigations reveal that the selfcompacting and anticracking performances of sidewall concrete with medium and low cementitious materials are well realized by adopting control technologies of viscosity and double regulation on hydration and expansion history of the concrete. Finally, the construction measures, including controlling mold temperature using a cooling water pipe, optimizing the pouring spacing and rate, insulation and moisture curing, a complete technical scheme of anticracking and seepage prevention of the working shaft sidewall concrete with large volume, and stepwise casting, are proposed. the engineering application results show that: The sidewall concrete is tightly connected with a ring frame beam, no crack and leakage appears in the working shaft sidewall with a maximum length of 53.6 m, and the cumulative onetime pouring length and thickness of 120 and 1.5 m, respectively.

Key words: shield tunnel; working shaft sidewall, anticracking and seepage prevention, selfcompact concrete, crack control