To determine the side rock resistance of pile more accurately

the composing and the influence factor of it need to be researched. The mechanism of friction and adhesion between pile and rock is analyzed. It is pointed out that pile-rock interface strength is different from rock shearing resistance; the ultimate side rock resistance of pile is determined by the weak one between pile-rock interface strength and rock strength. Four groups of compression and uplift comparative tests for concrete short piles in medium weathered rock are accomplished. The value of ultimate side rock resistance and the resistance ratio of uplift test and compression test are obtained. Because the upper rock restriction to the rock connected with pile is weaker in uplift test than in compression test; the side rock resistance in uplift test decreases distinctly comparing with the result of compression test. ADINA software is used to analyze the test piles. By comparing the calculated value of ADINA program with the test value

the interface strength condition of pile and rock is analyzed. It is discovered that the ultimate side rock resistance of test pile is determined by the pile-rock interface strength; and the interface adherence force is the main part of interface strength.