During the four piles static load field test

soil pressure boxes are arranged. With the testing of stress on the top of C-piles namely the rigid piles

the top of M-piles namely the semirigid piles

and soil between piles

the piles-soil stress ratio and load sharing ratio are calculated. Then

the stress state of piles and soil during the CM-piles composite foundation static load test is analyzed. Besides

combining the large plate test P-S curve after setting different thicknesses of cushion layer with the single C-pile static load test

the failure mode and cushion effect are analyzed. The test results are as follows. First

when the CM-piles composite foundation is working

C-pile top stress concentration phenomenon is obvious as the pile-soil stress ratio of C-pile are more than 10

while that of M-pile are less than 10. As the test loading

piles-soil stress ratio increasing gradually

increasing rate of pile-soil stress ratio of C-pile is larger than that of M-pile. Second

under the conditions of design load of CM-piles composite foundation

load sharing ratio among C-piles

M-piles and soil is around 6:3:1. Considering M-piles and soil between piles as a whole

namely

after the foundation treatment

it is more reasonable for the soil between piles compared to C-piles to have a pile-soil load sharing ratio of 6:4. Third

as the thickness of cushion layer increases

the CM-piles composite foundation settlement values increase. While the quality of C-pile is better and cushion failure mode is pierced by C-pile

the material and thickness of cushion layer should be properly selected.