Abstract：Combined with the practical project by using dry jet mixing(DJM) piles to treat the saturated loess under the Yinjiazhuang—Zhongchuan expressway in Gansu Province，two typical sections were selected to test the stress of the pile and the soil with the pressure gauge in the composite ground. In the two sections，one is the floating pile composite ground，the other is the end-bearing pile composite ground. On the basis of the test data，calculated the stress ratio of the pile to soil and the bearing capacity is calculated. The results show that：(1) the stress of the pile and the soil in the end-bearing pile composite ground is larger than that in the floating pile composite ground when the upper load is the same；(2) the stress ratio of the pile to the soil is focused on 3–8 in this case；(3) in the two kinds of composite ground，the calculated bearing capacity being brought into play is more closer to the real load if the soil is supposed to fail first；(4) the failure mode of the composite ground under flexible foundation is the initial soil failure，then the failure of the whole composite ground is induced.
