Field tests on double-pile foundation of bridges in high-steep cross slopes

To analyze the bearing capacity and load transfer mechanism of double-pile bridge foundation in high-steep cross slopes, field tests are carried out located on pier No. 6 in Sixi bridge of Zhangjiajie-Huayuan highway. On the basis of the received measurements of stresses, the distribution rules of the axial force, shaft resistance and moment are obtained. The in-situ results indicate that all the applied loads can be carried by the shaft resistance. In particular, the upper soil layer carries most of the applied loads in the condition that the applied loads are relatively small. The ultimate shaft resistance in the depth whose range varies from 2 to 5 times the pile diameter is very small. The ratio of shaft resistances respectively supported by soils to rocks decreases with the increase of the loads. The negative bending moment occurs near the pile top, and the fact shows that the front pile, back pile as well as tie beam, as an integration, support the external load together. A double-pile analysis model is established based on the finite bar element method, and the distribution form and magnitude of earth pressure are proposed through fitting calculation. The calculated results match well with the measured values, which can provide a reference for similar projects.