Study on the Effect of Moisture Content on the Shear Strength of the Overburden Covered by the Block Caving Method at Pulang Copper Mine
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摘要:
覆盖层的物料特性是自然崩落法能否顺利进行的重要因素，普朗铜矿自然崩落法的覆盖层为高原冰碛物散体，其抗剪强度参数与含水率密切相关。以高海拔环境下的冰碛物为研究对象，采用散体直剪实验方法，获得不同含水率条件下的高原冰碛物散体抗剪强度参数，探索含水率对高原冰碛物散体抗剪强度参数的规律关系。研究结果表明：高原冰碛物散体物质的黏聚力和内摩擦角均随着含水率的增加而减小，黏聚力与含水率之间呈现较强的对数关系，而内摩擦角与含水率之间呈现较强的指数关系；根据冰碛物散体抗剪强度参数随含水率的变化程度，黏聚力对含水率的变化较为敏感，而内摩擦角对含水率的变化敏感性较低，说明黏聚力对含水率的敏感性要强于内摩擦角，含水率对高原冰碛物散体抗剪强度的影响主要是通过黏聚力变化来体现的。研究成果可为自然崩落法高原冰碛物覆盖层研究提供一定的理论依据。
Abstract:The material characteristics of the overburden layer is an important factor for the success of the natural caving method. The overburden of the natural caving mining method in Plan copper mine is a granular body of plateau moraine, whose shear strength parameters are closely related to moisture content. Based on the direct shear test method, the shear strength parameters of moraine at high altitude were obtained under different water content conditions, the relationship between moisture content and shear strength parameters of moraine debris was also discussed. The results were as follows: the cohesion and internal friction angle of plateau moraine particles decreased with the increase of moisture content. There was a strong logarithmic relationship between cohesion and moisture content, and an exponential relationship between internal friction angle and moisture content. Based on the law of variation between shear strength parameters and water content of moraine, cohesion was more sensitive to the change of water content, while internal friction angle was less sensitive to the change of water content. The results showed that the sensitivity of cohesion to water content was stronger than that of internal friction angle. The effect of moisture content on the shear strength of moraine debris was mainly reflected by the change of cohesion. The research results in this paper can provide some theoretical basis for the study of glacial till cover layers in high−altitude areas.
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Key words:
- sublevel caving method /
- moisture content /
- moraine debris /
- shear strength /
- cohesion /
- internal friction angle
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表 1 矿区冰碛物样品的矿物成分
Table 1. Mineral composition of moraine samples from the mine
矿物名称 石英 绿泥石 钾长石 斜长石 云母 闪石 含量/% 44.2 20.8 14.2 12.5 5.3 3.0 
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表 2 矿区冰碛物样品的级配粒径组成
Table 2. Gradation size composition of moraine samples from the mining area
粒径/mm >23 23~20 20~10 10~5 5~2.5 2.5~1.25 1.25~0.63 <0.63 含量/% 12.8 1.5 8.3 8.9 11.8 13.3 12.2 31.2
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表 3 高原冰碛物散体实验方案
Table 3. Plateau moraine bulk test programme
物料类型 物料编号 含水率 实验条件 垂直荷载/kPa 天然混合料 ZJ1 10% 天然剪切 200、400、
600、800半饱和混合料 ZJ2 13% 13%含水率 饱和混合料 ZJ3 16% 饱和剪切
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表 4 高原冰碛物散体物料抗剪强度指标参数
Table 4. The shear strength index parameter of Plateau Moraine bulk material
物料编号 编号 正应力/kPa 剪切应力/kPa 实际含水率/% ZJ1 1# 200 102 9.65 2# 400 186 10.11 3# 600 268 9.07 4# 800 338 10.32 ZJ2 1# 200 79 13.67 2# 400 164 12.39 3# 600 223 13.58 4# 800 282 12.93 ZJ3 1# 200 67 16.89 2# 400 122 15.98 3# 600 166 16.57 4# 800 232 16.32
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表 5 高原冰碛物散体物料抗剪强度参数值
Table 5. Parameter values of shear strength of bulk materials from plateau moraines
散体类型 平均含水率/% 抗剪强度参数 黏聚力c/kPa 内摩擦角φ/(°) 天然散体物料 10 26 21.5 半饱和散体物料 13 20 18.4 饱和散体物料 16 12 15.0
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