Based on the three-tube parallel shield tunnel that cuts through under Hu-Hang Railway of R413 bid segment of the 9th route of Shanghai track traffic

two groups of centrifugal model tests

with one group with stratum reinforced and another not

have been done by the method of simulating stratum loss. The longitudinal effect regularity of lining inner force caused by three-tube parallel shield tunnel approaching constructed

has been studiced. The test result shows that the moment of flexion and axial force appear major change at arch lumbus of the left and right tunnel lining when the middle tunnel constructed. The longitudinal effect can be controlled effetely by stratum reinforcement but the influence also should be paid attention to. In the process of construction such method as strengthen slip casting and install longitudinal steel frame can be used for decreasing the influence on the lining duct piece especially on the joint caused by the longitudinal effect.