Abstract: Due to some problems such as difficulty in reserving pipe jacking construction holes, the inclination of open caisson and the insufficient bearing capacity of the support structure in the traditional support structure during pipe jacking construction, the efficiency and safety of pipe jacking construction will be seriously affected. To address these problems, a new type of profile steel- polymer composite fabricated support structure suitable for pipe jacking work shaft is developed. Through the combination of actual engineering field test and finite element numerical simulation, the soil settlement deformation around the work shaft and the mechanical response of the support structure during pipe jacking construction are analyzed, and the reliability of the new support structure for pipe jacking construction is verified. Finally, the main controlling factors affecting the mechanical properties of the support structure of the work shaft are obtained through an orthogonal simulation test. The results show that the spacing of support piles is the main controlling factor affecting the mechanical properties of the new support structure, and in the process of short-distance pipe jacking, the soil around the work shaft has different degrees of settlement, and the surface settlement in the jacking direction is the largest, and the surface settlement in the sidewall direction is the smallest, and the influence range on the surface settlement is about 2.7 times of the jacking distance. Moreover, the stress of supporting pile increases with the increase of pipe-soil interface friction, and the stress of supporting pile at the entrance is the largest. In the long-distance pipe jacking construction, the stress of the jacking surface is large in the early stage of pipe jacking. With the increase of the jacking distance, the stress of the sidewall and back wall increases, which is higher than that of the jacking surface. The research results can provide favorable suggestions for the optimal design of a new support structure of pipe jacking work shaft.

Key words: pipe jacking work shaft, assembled structure, profile steel-polymer, field test, finite element simulation, mechanical response