Four times of lateral loading tests of a instrumented model of a steel well which was 2.1m long and 50cm diametral were performed in the submerged sand. The results of measurements showed that the peak of subgrade reaction distribution at any depth was located along the center of the well, that it's magnitude of the maximum subgrade reaction was four times as large as the passive earth pressure at that depth, and that the Kubo's relation p=kxy1/2 was valid in this case also.
　Two calculation methods are herein proposed; the first is the modified Ikehara-Yokoyama's method and the second a graphical calculation method using the Kubo's
relation. Some design methods presented so far and the above two ones were examined by comparing with the test results. The first proposed method proved to be satisfactory as much as Mononobe's and Ikehara-Yokoyama's ones. Also the second proposed method conincided approximately with the test results. In the theory of the
second method, the authors expressed an idea that the coefficient of horizontal subgrade reaction was inversely proportional to the root of pile width. The calcul
ation for a short pile by PHRI method also gave a reasonable result.