Aiming at the mechanical characteristics of backfill in high-level stopes of Zhongguan Iron Mine in Hebei Province, analytical models for lateral pressure, shear stress and vertical stress of high-level stopes were established, and the influence laws of stope width, height and length on the stress distribution of backfill were clarified. A strength design model for backfill in high-level stopes with stress distribution taken into consideration was proposed, and the reliability of the model was verified through engineering application. The results show that the lateral pressure reaches the maximum at the bottom of the backfill on the side contacting uncemented or low-ratio cemented backfill; the shear stress increases first and then decreases, peaking at the middle of the backfill, and is significantly affected by stope width and height; the vertical stress of backfill increases linearly with stope length; when the stope length exceeds 45 m, the influence of exposed height on vertical stress becomes gradually prominent. Based on the comprehensive consideration of the stress distribution characteristics of backfill, the shear force at the contact surface of the surrounding rock and the included angle of the horizontal plane, three types of backfill strength design models were constructed. In combination with the working conditions of Zhongguan Iron Mine, a differentiated strength design scheme was selected. Industrial tests on site have verified the accuracy and reliability of the proposed backfill strength design model.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |