Dark Cave Stability Evaluation Based On Stochastic Medium Theory Of Highway Loess

With the development of infrastructure construction in loess regions of western China, shallow hidden cavities in loess are the high risk to the highway construction and transportation safety. So, working out effective methods of highway hidden cavity stability assessment is of great importance for highway foundation treatment and design. In this paper, the stability of highway hidden cavity in loess area is discussed and assessed based on the stochastic media theorv.A new method for loess hidden cavity assessment is presented on the basis of stochastic media theory. A simplified geometric model and an equivalent dynamic model of loess hidden cavity assessment are developed. With this method, the ground deformation resulted from the hidden loess cavities of different shapes, sizes and depths and their affected range are calculated and analyzed. The critical safety thickness of loess hidden cavity with different parameters is calculated. Using surface deformation and intensity of top layer structure as criterion of loess hidden cavity stability assessment, the effects of cavity shape parameters on surface deformation and critical safety thickness are analyzed, and the stability of loess hidden cavity is studied. The qualitative analysis on the relation of safety coefficient and ground loading with critical safety thickness is made. The results of this research are compared with the calculated results obtained by other different methods. Practicability and rationality of different methods are discussed. Operational procedure of the stochastic media theory and method in practical engineering is conceived.The following conclusions are got in this research: 1. The magnitude and distribution of ground subsidence due to hidden cavity are related not only with depth of hidden cavity but alsowith the size of cavity section and characteristics of stratum.2. The magnitude of maximum ground subsidence caused by hidden cavity increases with the augment of principle influence angle of stratum, cavity section size and cavity radial constringency and diminishes with the decrease of hidden cavity depth.3. The critical safety thickness of hidden cavity increases with the augment of hidden cavity section size, radial constringency, safety coefficient and surface loading. The critical safety thickness of hidden cavity is not sensitive to influence angle of stratum.4. The influence range on ground surface increases with the augment of hidden cavity depth and section size and decreases with augment of influence angle of stratum.