Model tests of road subsidence progress with underground cavities caused by cyclic dynamic load

Due to the cyclic dynamic load, the underground cavity will gradually develop into road subsidence. In view of this problem, this paper establishes model tests to simulate the whole developing process of road subsidence. The results show that as the cyclic dynamic load decreases, the limited cyclic loading times causing road subsidence increases exponentially. However, if there is a certain size of underground cavity, small cyclic dynamic load can also lead to road subsidence after sufficient cyclic loading times. The soil with larger maximum particle size and higher uneven coefficient has larger ultimate static strength and smaller ultimate dynamic strength. On the contrary, soil with smaller maximum particle size and smaller uneven coefficient has smaller ultimate static strength and larger ultimate dynamic strength. Larger thickness of the soil overlying the underground cavity will lead to larger ultimate static and dynamic strength. At the same time, the development of the road subsidence curve and the soil cracks under the cyclic dynamic load undergo three stages. Stage 1 is the initial consolidation settlement stage with short duration. In this stage, the soil is compacted by vibration and the ground surface has overall settlement with no obvious development of the observed soil cracks. Stage 2 is the uniform development stage with long duration and uniform development in settlement and soil cracks. The soil is subjected to the effect of shear vibrating. Stage 3 is the accelerated development stage with the shortest duration. The soil is subjected to vibration failure. The settlement and soil cracks develop rapidly until road subsidence occurs.