细尾矿砂破坏准则的测试与安全影响

摘要

为研究细尾矿砂破坏准则的具体形式和安全影响,利用HCA试验的方法测试了子午平面和π平面的破坏曲线;采用数值模拟的方法分析了所获破坏准则引起的尾矿坝安全系数变化.结果表明:子午平面的破坏曲线为单调递增;π平面破坏曲线在静水压力较小状态与Mohr-Coulomb准则一致,静水压力较大状态与Drucker-Prager准则一致,针对试验对象静水压力分界点可确定为200 kPa;若基于分界点在坝体内设置双重破坏准则,安全系数介于单独准则所得值之间,且Drucker-Prager准则单元所占比重介于31.33％ ～60.67％时,滑面区内Drucker-Prager准则单元数量变化,安全系数变化较明显,比重取其余值滑面区内Drucker-Prager准则单元数量不变,安全系数变化不明显.细尾矿砂破坏准则应为Mohr-Coulomb与Drucker-Prager组合而成的双重准则,组合过程需考虑静水压力的影响.%To study the specific form and safety influence of failure criterion for the fine tailings,the failure curves of meridian plane and π-plane were tested by the method of HCA experiment,and the change of safety factor of tailings dam caused by the obtained failure criterion was analyzed through the method of numerical simulation.The results showed that the failure curves of meridian plane were all increase monotonically,while the failure curves of π-plane were in accordance with the Mohr-Coulomb criterion under the situation of small hydrostatic pressure and in accordance with Drucker-Prager criterion under the situation of big hydrostatic pressure,and for the tested objects,the cut-off point of hydrostatic pressure could be determined as 200 kPa.If the double failure criteria were specified in the tailings dam on the basis of cut-off point,the safety factor was between the values of single failure criterion,and if the percentage of elements with Drucker-Prager criterion was in the range of 31.33％ to 60.67％,the number of elements with Drucker-Prager criterion in the slip surface zone would change,and the safety factor changed obviously,but the change of safety factor was not obvious for the rest values of the percentage because the number of elements with Drucker-Prager criterion in the slip surface zone was unchanged.The failure criteria of the fine tailings should be the double failure criteria which combined Mohr-Coulomb criterion with Drucker -Prager criterion,and the influence of hydrostatic pressure should be considered in the combination process.