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| Model testing on deformation characteristics of the locking steel pipe pile retaining structure by using 3D printing |
| WEI Shi1，DENG Chenglong1，LIANG Rongzhu1，2，WANG Xinxin3，WU Xiaojian1，3，SUN Lianwei3 |
| (1. Faculty of Engineering，China University of Geosciences，Wuhan，Hubei 430074，China；2. College of Civil Engineering and Architecture，Guangxi University，Nanning，Guangxi 530004，China；3. Shanghai Construction Group Co.，Ltd.，Shanghai 200080，China) |
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Abstract Locking steel pipe pile has advantages of quick construction efficiency and recycle utilization. Nowadays，it is widely used as a retaining structure in excavation engineering. Non-inner supported excavation with locking steel pipe pile retaining structure similar model test was carried out to investigate the deformation characteristics of locking steel pipe pile. To simulate the structural characteristics of locking steel pipe pile，three dimensional(3D) printing technology was creatively applied to manufacture locking steel pipe pile by using Somos? Taurus as printing base material. The similar excavation model test with locking steel pipe pile retaining structure was conducted in dry sand and the soils were filled using rain fall method. The excavation from initial state to retaining structure failure was simulated by manual excavation. The lateral displacement at the pile top，ground surface settlements and the bending moment of the piles were continuously measured during the whole process of excavation. The lateral deflection of model pile was back-analyzed using pile shaft strains. The testing results shown that the 3D printing technology can rapidly and accurately manufacture locking steel pipe model piles，which meet the model test requirement perfectly. The deformation of locking steel pipe pile and the ground surface settlement increased with excavation depth，the deflection of model pile was similar as cantilever beam subjected to distributed load. When excavation depth varies from shallow depth to structure failure，both of positive bending moment in model pile and the lateral displacement in pile top increased nonlinearly. However，the positions of maximum positive bending moment maintain range from 30–35 cm below the excavation face. As a retaining structure，the locking steel pipe piles possess a good integrality. The shear failure did not occur in the pile shaft when the retaining structure reached failure state. In non-inner supported retaining structure，the locking steel pipe pile was flexible structure and its safe installation ratio was suggested from 1.8 to 2.5，which was greater than the other rigid retaining structures.
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2020, Vol. 39 
