Shear behavior test of foamed concrete in Yangtze River shield tunnel of China-Russia Eastern Gas Pipeline Project

Yangtze River shield tunnel is an important control project of China-Russia Eastern Gas Pipeline Project (Yongqing-Shanghai). The ultra-length tunnel (10.226 km) caused many engineering problems. In particular, the high sensitivity of pipeline stress to the transportation temperature and the large axial displacement of the pipeline at the shaft bring about potential hazards to the later pipeline operation. In order to solve the above engineering problems, a design plan was put forward to constrain the pipeline displacement by filling foamed concrete in the tunnel. Hence, to reasonably evaluate the constraint capacity of foamed concrete, laboratory tests were performed to determine the shear strength of gas pipeline (3LPE anti-corrosive pipeline)-foamed concrete-concrete segment. The average shear strength obtained is 0.25 MPa, which meets the requirement of the condition to ensure no relative displacement between the 3LPE anticorrosive pipeline and the foamed concrete under the action of temperature stress (the shear strength should not be less than 0.1 MPa). Generally, the experimental results meet the engineering requirements. In addition, the feasibility of constraining the axial displacement of 3LPE anticorrosive pipeline with foamed concrete was verified by experimental research, which could provide reference for pipeline design and installation for super-long tunnels in the future.