Tolerance and Constructability of Soldier Piles in Slurry Walls

Abstract

Process capability (PC) characterizes the variation in a parameter of a process’s output. From a constructability perspective, investigating PCs for geometric variation is important when specifying tolerances for all construction processes. This paper investigates a case involving soldier piles used in a slurry wall and compares the design specified tolerances to as-built field data. As with other cases investigated by the writers covering many major construction processes, this case also shows that designers specify tolerances based on tacit estimates of variation limits, not PCs. Consequently, the PCs consistently exceed the design specified tolerances, preventing the possibility of proper tolerance management and causing problems to manifest during construction. The writers conclude that variation estimates are an inaccurate basis for specifying tolerances and instead should be based on PCs.