Abstract: Rock mass of the foundation of the Second Hanjiang Bridge in Yun County consists of soft rock and extremely soft rock which are formed from Cretaceous Period to Paleogene Period. The cementation is unfavorable and they are easily degraded under disturbance. The foundation of the bridge is bored-pile socketed in rock. Laboratory physical and mechanical tests on rock samples as well as in-situ mechanical tests on the rock mass were carried out in the detailed prospecting stage. Of the adopted test methods for the mechanical properties of rock mass, the method for the test of lateral frictional resistance force of pile is a newly proposed one. The correlation between bedrock load and settlement deformation was investigated based on in-situ tests. Permissible values of resistance force at the end of pile and lateral frictional resistance force of the pile were both obtained, hence the limitations of laboratory tests were overcome. Suggested values of the resistance force at the end of pile and the lateral frictional force were proposed and therefore the optimization design is provided with reliable basis.      

Key words: South-to-North water transfer, Danjiangkou reservoir region, Second Hanjiang Bridge in Yun County, bored pile socketed in rock, in-situ mechanical test of rock mass, resistance force at the end of pile, lateral frictional resistance force of pile