An experimental study of the parameters influencing ultimate bearing strength of weak floor strata using physical modeling

摘要

The evaluation of the bearing strength characteristics of floor strata during an excavation process while under heavy loads from an overlying rock mass is one of the important factors in strata control of any underground mine. Plate loading tests on simulated floor strata were carried out for varying geotechnical conditions of weak floor strata. The physico-mechanical properties of weak floor strata evaluated in the experiments include unconfined compressive strength (σ_c), elastic modulus (E), Poisson's ratio (γ) angle of friction (φ), and the moisture content (MC). The paper summarizes the results of (1) bearing strength tests using different sizes of circular loading plate (2) influence of various physico-mechanical parameters of weak floor strata on its floor bearing strength and (3) bearing strength analysis of weak floor in jointed rock mass. The outcome of the results show that the ultimate bearing strength decreases considerably with increase of footing plate size. The experimental results strongly support the earlier field investigation findings depicted by Zhanjing et al. (1992). Thus the contradictions about the plate size effect on bearing strength (Katsutoshi et al., 1998) are further eliminated. It was further investigated that apart from the plate size, ultimate bearing strength is strongly correlated with uniaxial compressive strength. A better correlation between moisture content and ultimate bearing strength with a regression coefficient of 0.91 was also achieved. An excellent correlation between angle of friction (φ) and ultimate bearing strength was found.