Field testing study of deep soil displacement distribution during shield excavation

In the construction of urban rail transit (URT), how to predict and control the deep soil displacement caused by shield excavation to ensure the safety of existed underground structures is a larger problem during designs and constructions nowadays. Taking the shield construction of line 15 as the research background, this article adapted the method of field test to study the deep soil displacement distribution rule in the direction of shield advancing when the shield is excavating. Except the central measuring points of the shield, the other points ranging between 28.8m and 7.2m from cutting wheel to exterior protected construction indicates that, soil displacement direction is much the same as the excavation direction; and the displacement distribution curve relatively coincides with linear curve; while the displacement direction in the center of the shield is opposite to excavation direction,and the displacement distribution relatively coincides with linear curve from ground surface to the top of the shield, and relatively coincides with normal distribution curve from the the top of shield to the deep area of measuring points, all the measuring points ranging from 7.2m to 3.6m shows that the direction of soil displacement is the same with the excavation direction and with the increasing of shield excavation displacement, the displacement distribution can better coincides with the normal distribution curve, and the maximum displacement point is just in the center of shield or lm above the shield.