Experimental Evaluation of Multiple Frost Heaving Parameters for Preflawed Granite in Beizhan Iron Mining, Xinjiang, China

Abstract

Ice-driven mechanical weathering in cold regions is considered a main factor impacting the stability of rock mass. In this work, the response surface method (RSM) was employed to evaluate and optimize the multiple frost heaving parameters to seek the maximum frost heaving force (FHF), in combination with experimental modeling based on a specially designed frost heaving force measurement system. Three kinds of rocks were prepared with parallel flaws in it having different flaw width, length, and cementation type, and these factors were used to fit an optimal response of the maximum FHF. The experimental results reveal five distinguished stages from the frost heaving force curve, and they are inoculation stage, explosive stage, decline to steady stage, recovery stage, and sudden drop stage. The sensitivity analysis reveals the influential order of the considered factors to peak FHF, which is the rock lithology, flaw width, flaw cement type, and flaw length. For low-porosity hard rock, increasing flaw width, flaw length, and flaw cement strength can improve the probability of frost heaving failure. It is suggested that rock lithology determines the water migration ability and influences the water-ice phase transformation a lot.

On the Fracture Evolution and Instability of Pyrite-Filled Marble Exposed to Freeze-Thaw-Compression Loads

“…The pyrite band, as a typical geological discontinuity unit, is sound developed in marble of the Jiama open pit mine of China. Although plenty of efforts have been performed to reveal the effects of the preexisting flaws, such as preflaws, bedding plane, interbeds, and joints, on rock failure [5,9,31,36], the primary pyrite band on rock geomechanical behaviors is not well understood. Especially, for pyrite-filled rock in cold regions, the influence of freeze-thaw cycle on rock structural deterioration and failure evolution is poorly revealed.…”

“…Actually, rock mass is not an intact material; plenty of discontinuities, e.g., layers, joints, faults, foliation cleavages, and vein, develop within it and the existence of those discontinuities predominantly impacts its deformation and failure mode [4][5][6][7]. In cold regions, what is more serious is that under freeze-thaw conditions, 9% volume expansion will occur when water turns into ice [8][9][10][11][12], and frost heave pressure will be generated within the existing cracks or discontinuities. The frost heave pressure promotes the expansion of geological structural plane, which leads to the increase of fracture opening and fracture length, and the deterioration of rock structure.…”