Through the indoor model tests

lateral earth pressures exerted by natural foundation and rigid pile composite foundation against rigid retaining walls without any displacements are measured. The distribution of lateral earth pressures of rigid pile composite foundation is obtained by the comparison with that of natural foundation. It is believed that participation of pile in rigid pile composite foundation makes magnitude and distribution of lateral earth pressure different from natural foundation. In this place

pile participation includes the deep transfer function of pile load

the influence of pile negative friction and the pile "block" effect on level additional stress of soil between piles. The influence range of lateral earth pressure of rigid pile composite foundation with surcharge is deeper than that of natural foundation. Besides

the value of lateral earth pressure of rigid pile composite foundation is smaller than that of natural foundation at the same location under the same subgrade pressure. In the test conditions of this study

the total and the additional earth pressure exerted by the rigid pile composite foundation on the rigid retaining walls are about 43.3%~80.1% and 15.9%~59.8% of the total earth pressure of the natural foundation respectively when the load level reaches the characteristic value of the foundation capacity within the range of 0.35 to1.4 m from the rigid retaining wall to the building.