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模袋法是解决上游法细粒尾矿堆坝难的一种新方法。为研究模袋法尾矿坝筑坝模袋的基本力学性能,采用与云南省某尾矿坝施工现场一样的土工布和尾砂,通过斜坡滑移、直剪、无侧限压缩试验,对固结不同时间的小尺寸尾矿坝筑坝模袋进行了摩擦和受压性能的试验研究。斜坡滑移试验表明,若含水率相对较低,则模袋间的摩擦系数较大;直剪试验测得固结8 d的模袋间内摩擦角约为28o,黏聚力约为40 k Pa;在无侧限压缩条件下,固结1 d和3 d的模袋在受压过程中,其弹性模量都表现为“大-小-大”的变化形式。由于土工布和尾砂的共同作用,模袋的极限抗压强度远大于单纯尾砂堆积体的极限抗压强度。当压应力达到模袋所能承受的极限荷载时,通常会在模袋底部靠近模袋边缘处发生土工布的撕裂破坏,采用主动土压力理论分析了发生破坏的原因。本试验研究可以为模袋法尾矿坝的实践提供理论指导。
Bag method is to solve the upstream method of fine tailing dam heap is a new method. In order to study the basic mechanical properties of the mold bag for damming of tailing dams, the geotextile and tailing sand at the tailings dam construction site in Yunnan Province are adopted. Through the tests of slope slip, direct shear and unconfined compression, Experimental study on the friction and compression properties of a small size tailings dam dam bag consolidated at different times. The slope slip test shows that the coefficient of friction between the mold bags is relatively large if the water content is relatively low. The direct friction test results show that the internal friction angle between mold bags is about 28% and the cohesion is about 40 k Pa. Under unconfined compression conditions, the elastic modulus of the mold bags consolidated for 1 d and 3 d during the compression process showed a variation of “big - small - big”. Due to the joint action of geotextiles and tailings, the ultimate compressive strength of the bag is far greater than the ultimate compressive strength of the tailings. When the compressive stress reaches the ultimate load that the mold bag can bear, the tearing of the geotextile usually occurs at the bottom of the mold bag near the edge of the mold bag. The reason of the failure is analyzed by the theory of active earth pressure. The experimental study can provide theoretical guidance for the practice of mold bag tailing dam.