Abstract
To develop a new gangue polymer filling material with low compressive ratio, this paper intends to add high water cementing material to the gangue for backfilling. Uniaxial and tri-axial bearing experiments were conducted to study its bearing characteristics and residual strength. Based on Hock-Brown model theory, it is proposed that friction angle φr can be introduced to substitute model parameter mi, and the degree of cohesion loss can characterize the value of s. So the improved H-B model is established to characterize the residual strength of materials with ductile failure characteristics. The results show that the compressive strength of high water filling material increases linearly corresponding to the rise of confining pressure, and its strength characteristics conform to Mohr-Coulomb strength criterion. The ductile failure characteristics of the sample endow it with high residual strength, which in turn qualifies it for underground filling. After the introduction of cohesion and friction angle, the improved H-B criterion can fit the residual strength curve of the high water filling material more competently. The fitting coefficient of the samples with three water contents is 1.00, 0.99, and 1.00, respectively. The improved H-B model of residual strength demonstrates the change rule of residual strength of the samples corresponding to the change of confining pressure; under tri-axial loading, the angle between fracture surface and axial direction becomes larger as the confining pressure rises; and the failure mode of the material transforms from splitting failure to shear failure.
Highlights
China’s energy structure is dominated by coal, and the extraction of coal causes damage to farmland and ecological environment [1,2,3]
The residual strength values of rocks under different confining pressure conditions are determined through triaxial compression tests of rocks, and the residual strength parameters of rocks are fitted by the M-C model or the H-B model [22]
As the moisture content of the high-water material increases, there is more pore water inside, which ensures that the loss of cohesion is small, and the residual strength of the high-water material accounts for a larger proportion of the peak strength
Summary
China’s energy structure is dominated by coal, and the extraction of coal causes damage to farmland and ecological environment [1,2,3]. Residual strength characteristics of high water materials water material, and paste and so on [6,7,8]. Many researchers have studied the hydration mechanism, strength and bearing characteristics of high-water materials [9,10,11,12,13]. Solid particles and water are the main components of high-water material, the relative content of which directly affect its physical and mechanical properties. The determination of residual strength plays an important role in rationally evaluating the stability of geotechnical engineering and effectively exerting the bearing capacity of rocks [23]. This study conducted experimental research on the stress-strain curve, bearing characteristics, and residual strength of high water-cementing material with different water contents. The research results can provide reference and guidance for filling mining
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