Lateral load tests of 33 model steel piles were perf ormed in cohesionless soil to study the behaviour of short piles with the following results.
(1) Piles subject to lateral force are brought into the following four categories according to the ratio Er, which is the ratio of L and lm1. (L is the length of embedment of a short pile and lm1 is the depth of the first zero point of moment of a corresponding long pile).
　　　　Er>1.5　　　long pile
　1.5>Er>1.0　　1st transition range　　　short pile
　1.0>Er>0.6　　2nd transition range　　　short pile
　0.6>Er　　　　　rigid pile　　　　　　　　　　　　short pile
　A pile of the first transition range behaves, when laterally loaded, quite similar to the corresponding long pile, but doesn't have sufficient embedment to be completely fixed in the ground at the pile tip.
　A pile of the second transition range shows quite large deflection and inclination compared with a long pile and shows fair amount of deflection at the tip.
　A pile with Er smaller than 0.6 behaves like a rigid body and the effect of the bendinf of the pile on pile behaviours can be neglected.
(2) Deflection, inclination and bending moment of a laterally loaded short pile can be estimated by means of comparison with those of a long pile based on the Er ratio.
(3) The distribution of soil reaction against pile surface at the failure can be expressed by two straight lines with sufficient acuracy for practical purposes. The first straight line coincide with the line of passive earth pressure starting from the ground surface.
(4) The failure of a short pile occures when the soil reaction reaches the value of passive earth pressure at the pile tip.