Abstract: Impact roller(IR) compaction has been widely used for ground improvement in highway, airport engineering at home and abroad. The IR applies high energy to the ground and densifies deeper than conventional static and vibrating rollers and has the virtues of saving construction period and cost. As a result, attentions from academic circles and engineering circles have been drawn gradually. However, the theoretical research of IR compaction technique is inadequate and far behind its engineering practice. To promote reasonable application of IR compaction technique, a laboratory study based on self-devised impact roller simulation device was carried out to investigate effects of mass of impact wheel and towing speed on the effectiveness of IR compaction. The impact load form and the transmission and attenuation of impact energy in dry sand during IR compaction were also investigated. The results of laboratory cone penetration tests show that both mass of wheel and towing speed have significant influence on the IR compaction effectiveness. The effectiveness of IR compaction is better when heavier wheel is used and can be increased significantly by increasing the mass of impact wheel. There is an optimum towing speed to achieve the best effectiveness of IR compaction. The results of stress measurement in tests show that the impact load is a transient single pulse and the load distribution is not uniform with higher values in the centre of impact contact area. It also can be found that the impact energy mainly transfers in vertical direction in form of transient single pulse and attenuates quickly in form of negative power function.

Key words: ground improvement, impact roller compaction, model test, sands