Experimental study on unloading deformation mechanisms of soft base dumps of open-pit mines
WANG Yukai1，SUN Shuwei1，2，PANG Bo1，LIU Liu1
(1. School of Energy and Mining Engineering，China University of Mining and Technology(Beijing)，Beijing 100083，China；2. State Key Laboratory Coal Resources and Safe Mining，China University of Mining and Technology(Beijing)，Beijing 100083，China)
Abstract：In order to systematically study the unloading deformation mechanisms of soft base waste dumps，taking the waste dump with a silty clay base of Dagushan Iron Mine as the research background，the deformation and failure processes of the waste dump under natural(hard base) and saturated(soft base) conditions are compared，and the displacement distribution and evolution law of the waste dump are acquired by speckle analysis and point tracking. The test results indicate that the stability of the soft base waste dump is obviously worse than that of the hard base waste dump. The deformation failure of the hard base waste dump shows a collapse-traction-push pattern，developing from the low-grade slope towards the high-grade slope，while due to the uneven unloading settlement between the front and back parts of the waste dump，the deformation failure of the soft base waste dump mainly controlled by the soft base presents a cycle of subsidence，breakage and slip until the failure of the whole slope above the soft base. Tension cracks in the hard base waste dump are caused by the uneven horizontal deformation while dislocation cracks in the soft base waste dump results from the uneven unloading settlement. It is suggested that dynamic consolidation and borehole grouting methods should be adopted to reinforce the soft base of the waste dump and，at the same time，a perfect drainage system should be built to reduce the softening of the base soil. The research results can provide reference for the research and treatment of unloading deformation of soft base dumps.
张 超，杨春和. 粗粒料强度准则与排土场稳定性研究[J]. 岩土力学，2014，35(3)：641-646.(ZHANG Chao，YANG Chunhe. Investigation on strength criterion of coarse grained material and stability analysis of waste dump[J]. Rock and Soil Mechanics，2014，35(3)：641-646.(in Chinese))
[3]
孙世国，杨 宏. 典型排土场边坡稳定性控制技术[M]. 北京：冶金工业出版社，2011：1-6.(SUN Shiguo，YANG Hong. Stability control technology of typical dump slope[M]. Beijing：Metallurgical Industry Press，2011：1-6.(in Chinese))
[5]
POULSEN B，KHANAL M，RAO A M，et al. Mine overburden dump failure：a case study[J]. Geotechnical and Geological Engineering，2014，32(2)：297-309.
[6]
BEHERA P K，SARKAR K，SINGH A K，et al. Dump slope stability analysis-A case study[J]. Journal of the Geological Society of India，2016，88(6)：725-735.
[11]
王 俊，孙书伟，陈 冲. 饱水黄土基底排土场地质力学模型试验研究[J]. 煤炭学报，2014，39(5)：861-867.(WANG Jun，SUN Shuwei，CHEN Chong. Geo-mechanical model experiment research of dumping site on loess basement[J]. Journal of China Coal Society，2014，39(5)：861-867.(in Chinese))
[13]
李 跃，杨永生，毛权生，等. 基于三维地质模型的排土场边坡整体稳定性探究[J]. 岩土力学，2013，34(增1)：533-539.(LI Yue，YANG Yongsheng，MAO Quansheng，et al. Researches on general stability for dump slope based on three-dimensional geologic model[J]. Rock and Soil Mechanics，2013，34(Supp.1)：533-539.(in Chinese))
[15]
尹光志，李小双，李耀基. 底摩擦模型模拟露天转地下开挖采空区影响下边坡变形破裂响应特征及其稳定性[J]. 北京科技大学学报，2012，34(3)：231-238.(YIN Guangzhi，LI Xiaoshuang，LI Yaoji. Simulation on the deformation and failure response features and stability of a slope from open pit mining to underground mining under the effecting of excavation goaf by the floor friction model[J]. Journal of University of Science and Technology Beijing，2012，34(3)：231-238.(in Chinese))
[9]
WANG J C，CHEN C. Stability analysis of slope at a disused waste dump by two-wedge model[J]. International Journal of Mining Reclamation and Environment，2016，31(8)：1-14.
[16]
许 强，张登项，郑 光. 锦屏I级水电站左岸坝肩边坡施工期破坏模式及稳定性分析[J]. 岩石力学与工程学报，2009，28(6)：1 183- 1 192.(XU Qiang，ZHANG Dengxiang，ZHENG Guang. Failure mode and stability analysis of left bank abutment high slope at Jinping I Hydropower Station[J]. Chinese Journal of Rock Mechanics and Engineering，2009，28(6)：1 183-1 192.(in Chinese))
[19]
HE L，WU G，WANG H. Study of base friction simulation tests based on a complicated engineered bridge slope[J]. Frontiers of Structural and Civil Engineering，2012，6(4)：393-397.
STEIAKAKIS E，KAVOURIDIS K，MONOPOLIS D. Large scale failure of the external waste dump at the “South Field” lignite mine，Northern Greece[J]. Engineering Geology，2009，104(3/4)：269-279.
[7]
ADAMCZYK J，CA?A M，FLISIAK J，et al. Slope stability analysis of waste dump in sandstone open pit osielec[J]. Studia Geotechnica et Mechanica，2013，35(1)：3-17.
[8]
OGBONNAYA I，CHIDINMA C. Slope stability analysis of mine waste dumps at a mine site in Southeastern Nigeria[J]. Bulletin of Engineering Geology and the Environment，2019，78(4)：2 503-2 517.
[10]
陈 冲. 软弱基底排土场边坡破坏模式与稳定性分析[博士学位论文][D]. 北京：中国矿业大学(北京)，2018.(CHEN Chong. Failure mode and stability analysis of slope dumped on soft layer[Ph. D. Thesis][D]. Beijing：China University of Mining and Technology (Beijing)，2018.(in Chinese))
[18]
王 华. 桥基岸坡变形破坏机制物理模拟研究[J]. 岩土力学，2011，32(7)：2 034-2 038.(WANG Hua. Study of deformation and failure mechanism of bridge foundation slope with physical simulation method[J]. Rock and Soil Mechanics，2011，32(7)：2 034-2 038.(in Chinese))
[12]
黄刚海. 强降雨入渗下复杂地形排土场稳定性分析[J]. 岩土工程学报，2013，35(增2)：292-295.(HUANG Ganghai. Stability analysis of waste dump with complex terrain under heavy rainfall infiltration[J]. Chinese Journal of Geotechnical Engineering，2013，35(Supp.2)：292-295.(in Chinese))
[17]
赵红泽，杜海瑞，苏海云，等. 露天矿多煤层软岩复合边坡底摩擦实验研究[J]. 煤炭学报，2018，43(10)：2 724-2 731.(ZHAO Hongze，DU Hairui，SU Haiyun，et al. Basal contact friction experiment of composite slope containing soft rock and multiple seam in open pit[J]. Journal of China Coal Society，2018，43(10)：2 724-2 731.(in Chinese))
[14]
宋子岭，刘文坊，范军富，等. 倾斜基底内排土场边坡稳定性分析[J]. 金属矿山，2018，(2)：179-183.(SONG Ziling，LIU Wenfang，FAN Junfu，et al. Analysis of the inner dumping slope stability with inclining basement[J]. Metal Mine，2018，(2)：179-183.(in Chinese))
[20]
冯文凯，石豫川，柴贺军，等. 缓倾角层状高边坡变形破坏机制物理模拟研究[J]. 中国公路学报，2004，17(2)：33-37.(FENG Wenkai，SHI Yuchuan，CHAI Hejun，et al. Study of mechanism of deformation failure of a low-angle bedded high slope with physical simulation method[J]. China Journal of Highway and Transport，2004，17(2)：33-37.(in Chinese))
2020, Vol. 39 
