Abstract: The shield thrust should be reasonably controlled to regulate the earth pressure balance (EPB) shield when obliquely cutting through an underground diaphragm wall. The Nanning rail transit line 5 obliquely crosses the underground diaphragm wall of the Guangxi University station of line 1. The rockbreaking load of the EPB shield cutters and the cutterhead is analyzed as well as the interaction between the shield and soil. Furthermore, the vector calculation of the static equilibrium equation of shield action load is conducted using MATLAB software based on a theoretical model of the shield thrust load. The shield thrust is computed when obliquely cutting through the underground diaphragm wall and is compared with practical results to verify the rationality of the modified theoretical model. The comparative results demonstrate that the calculated shield thrust deviates 20%, which is acceptable for overall construction. The total shield thrust is recommended to be 15 000 to 20 000 kN for the undercrossing section.

Key words: shield tunnel, earth pressure balance shield; composite strata, rock breaking of cutters, thrust, MATLAB