Abstract: The monitoring results of shell earth pressure and jacking force of quasi-rectangular pipe jacking with a large crosssection in an underpass project at Songhu Road-Sanmen Road are compared with calculated results in codes using a quantitative method of theoretical and data analysis. The empirical coefficient is introduced to analyze the squeezing effect of quasirectangular pipe jacking head. The results show the following. (1) The calculated shell earth pressure using the soil column and Rankine earth pressure theories is relatively small. (2) The jacking force is linear with the mileage, where unit external friction is the slope, and frontal resistance is the intercept. (3) The circular section is the basis of the calculation methods of the unit external friction of quasirectangular pipe jacking tunnel given in the 2008 and 1997 editions of Code for Construction and Acceptance of Water and Sewerage Pipeline Works. For the quasirectangular pipe jacking tunnel in this project, the calculation result from the 2008 edition is 20% smaller than the actual value. (4) For the sandy silt ground in Shanghai, the lateral coefficient of control earth pressure is recommended to be 0.8.

Key words: quasi-rectangular pipe jacking with large cross-section, sandy silt, earth pressure, jacking force