比奥固结理论下基于有效应力法的尾矿库稳定性分析

Stability analysis of tailings pond based on effectivestress method under Biot consolidation theory

抗滑稳定计算是尾矿库安全评价的重要内容。由于无法有效估算因尾矿库上升而引起的超静孔隙水压力,目前常采用总应力法进行稳定性分析。然而,尾矿库的整个生命周期内,均可能存在超静孔隙压力,且该部分超静孔隙压力的影响不可忽视。以某平地型尾矿库为例,基于比奥固结理论,采用有限单元法定性分析尾矿库断面堆坝期和退役期超静孔隙压力的产生和消散,并以此进行有效应力法的稳定性计算。结果表明:1)超静孔隙压力在堆坝末期达到最大,约为130 kPa,全部消散需要约28 a;2)在堆坝末期,利用有效应力法计算的抗滑稳定安全系数为1.486,随着坝体有效应力的增长,超静孔压全部消散后的安全系数达到1.648,增长幅度约为11%;3)采用有效应力法可以较为细致地考虑尾矿库上升过程中超静孔隙水压力对坝体稳定性的影响,且结果更为科学可靠。

The calculation of anti-slip stability is an important part of the safety evaluation of tailings pond.Since it is not possible to effectively estimate the excess pore water pressure caused by the rise of the tailings pond,the total stress method is often used for stability analysis.However,there may be excess pore water pressure in the whole life cycle of the tailings pond,and the influence of this part of the excess pore water pressure cannot be ignored.Based on Biot’s consolidation theory,a flat tailings pond is taken as an example,and the finite element method is used to qualitatively analyze the generation and dissipation of excess pore water pressure in the section of tailings pond during dam-filling and decommissioning,and then the stability calculation of the effective stress method is carried out.The results show that:1)The excess pore water pressure reaches the maximum at the end of the dam-filling,which is about 130 kPa,and it takes about 28 a for it to dissipate completely;2)At the end of dam-filling,the safety factor of anti-sliding stability calculated by effective stress method is 1.486,and with the increase of effective stress of dam body,the safety factor after excess pore water pressure is completely dissipated reaches 1.648,with an increase of about 11%;3)The effective stress method can be used to consider the influence of excess pore water pressure on the stability of the dam body during the rising process of the tailings pond in detail,and the results are more scientific and reliable.