Abstract：Based on the established similarity law of composite soil-nailed supporting filled sidewall(slope) before rainfall，the conditions，methods，results and conclusions of large-scale similarity model test are discussed. The study shows that the technique of composite soil-nailed supporting can reduce the displacement of filled sidewall (slope) remarkably. The vertical displacement and displacement rate of the filled sidewall(slope) supported with composite soil-nailed are 0.005 times of those of the filled sidewall(slope) without supporting. The horizontal displacement and displacement rate of the former are 0.021 times of those of the latter. The peak strain line of horizontal anchor-pipes and the remarkable displacement line of the observation lines of the former are close to the final slump section(line) of the latter. Their distribution shape and position are very close. The result shows that the standpoint that the slump line will stand back after reinforcement is not correct. The strain of the inner ends of all horizontal anchor-pipe is not zero. This has testified the presence of the reinforcement effect on composite soil-nailed support.
