EXPERIMENTAL STUDY OF REDUCTION COEFFICIENTS α AND β OF CEMENT-SOIL PILES COMPOSITE FOUNDATION

The calculational formula for bearing capacity of single pile with coefficient α and bearing capacity of composite foundation with coefficient β are shown in Technical Code for Construction Foundation Treatment.In order to get the value scopes of α and β which are suitable for this region and provide revision data for future code revision,the reinforcement treatment of representative silt soil foundation is carried out by means of cement-soil mixing pile in the Pearl River Delta area.And then,the load test is performed on single pile,natural foundation and four cement-soil mixing piles composite foundation,which is set with four kinds of thickness cushions.Based on analysis and calculation of the test data,the value ranges of the reduction coefficient α and β in the bearing capacity formula in the code are modified.Finally,the influence of cushion thickness on the bearing capacity of composite foundation is analyzed.It is suggested that the value range of cushion thickness is 200-400 mm,which can provide reference for design of cement-soil mixing pile composite foundation in the Pearl River Delta area.