Experiment Research of Bearing Behavior on Lime-Soil Pile and CFG Pile Rigid-Flexible Pile Composite Subgrade

Rigid-flexible pile composite foundation of lime-soil pile and CFG pile can eliminate collapsibility and improve bearing capacity of subgrade. Five kinds of load test of large model casing in 150 cm × 100 cm × 100 cm have been made for research working properties in multi-type-pile composite foundation. We respectively designed fulfilled subgrade, lime-soil pile composite subgrade, CFG pile composite subgrade, lime-soil pile and CFG pile composite subgrade (4 pile type), lime-soil pile and CFG pile composite subgrade (9 pile type). In the test, we use the dial indicator measuring displacement and the pressure cell measuring the soil stress between piles in multi-type-pile composite foundation. By analysis load-settlement curve and load-sharing ration pile and soil in different multi-type-pile composite foundation, contrast to load-bearing characteristics between conventional composite foundation and multi-type-pile composite foundation. The results indicate that bearing mechanism of rigid-flexible pile composite subgrade is the flexible pile and the adjacent soil undertakes most of the load when the load is small, with the increase of load, the adjustment of the mattress layer plays a role, the rigid pile bearing capacity rapid increase and decision the ultimate bearing capacity of rigid-flexible pile composite foundation. The stress ratio of soil, lime-soil pile and CFG pile equal to 1:1.8:5.7 when the composite foundation failed. Combined with practical engineering, we put forward a practical design formula for calculation of bearing capacity in rigid-flexible pile composite foundation