Model Test Study on a Shield Tunnel Adjacent to Pile in the Sub-Clay of a Coastal Area

In this study, a model test system of shield driving adjacent to pile is realized to study the response of surrounding rock and pile induced by an advanced shield tunnel in silty clay layer in a coastal area. The function of automatic pushing and the synchronous grouting of the shield were partially simulated. Similar materials of lining, soft rock and pile, were developed. A total of 33 sets of orthogonal model tests were designed to study the progressive failure caused by excavation in silty clay and the change in stratum displacement and soil pressure; the displacement and internal force response of the pile were also analyzed. The following conclusions can be given: (1) the best grouting filling coefficient range of the shield test for the case study is 1.4 to 1.6; (2) the fitting of the experimental data to obtain the settlement through the width parameter suggests that the K value of the surrounding rock is decreased by 0.075 at least, and the K value increases with the increase in pile-tunnel distance and decreases with the increase in pile depth; and (3) the weak surrounding rock in the tunnel system can be divided into five zones according to the displacement and pressure change in soft surrounding rock and the pile response in the case study. The key condition control factor was also determined.