Full scale in-situ static loading tests on pile groups in soft soils

The bearing characteristics of pile groups in soft soils are complex. At present there are few full scale tests on in-situ pile groups at domestic and abroad. Full scale tests on bored pile groups are conducted to explore the performance of pile groups in soft soils in Jiangning District of Nanjing City. The pile diameter is 400 mm, and the pile length is 20 and 24 m. The loading tests are carried out on a single pile and pile groups with nine piles. Steel bar meters are fixed in the piles to measure the axial force. Pressure cells are placed at the top of the piles to get the accurate load on them. The data of the tests are listed to show the comparison of settlement, axial force, side resistance and load distribution of the single pile and pile groups. The measured values of counterforce of pile head and the effect coefficient of pile groups are compared with those calculated by different kinds of theoretical methods. The results show that the load distribution calculated by the elastic theory in the pile groups has larger difference compared with the measured value. The results of the formula for pile group effect coefficient considering stress superposition and the Converse-Labrre's formula for pile group effect coefficient agree well with the measured values.