水环境作用下采动诱发冲积层沉降特征及机理分析
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摘要
为了研究水环境作用下采动诱发冲积层沉降机制,基于3个矿井的实测数据,分析了厚含水冲积层下采动地表沉降特征,基于有效应力原理,构建了潜水含水层和承压含水层土体压缩计算模型,研究了水环境变化对土体压缩量的影响,并结合现场实测资料对模型进行了分析和验证.结果表明:在厚含水冲积层下开采,地表沉陷波及范围远超一般地质采矿条件下的影响范围,水环境和冲积层的联合作用是导致地表沉陷异常的根本原因.潜水含水层土体压缩量与水位降深之间呈抛物线增长关系,承压含水层土体压缩量与水头降深呈线性增长关系,水头降深越大,土体的压缩量就越大.模型预测均方根误差为±8mm,相对中误差为6.5%,实测值与理论计算值相吻合,采用所构建的土体压缩模型能够对矿井疏排水产生的地层压缩量进行合理计算和预测.
To study the mechanism of alluvial strata subsidence induced by coal extraction under the action of groundwater,surface settlement characteristics under thick alluvium overlaid condition were analyzed based on in-situ measurement data of three coal pits.Calculation models of soil compression were also developed for aquifer and confined water-bearing alluvial strata with the theory of effective stress.Moreover,the influence of alteration of groundwater table and soil mechanical parameters in alluvium strata on soil consolidation was discussed.Finally,the proposed models were analyzed and substantiated in accordance with field measurement data.The results indicate that extending scope caused by surface subsidence under thick water-bearing alluvium condition far exceeds that under normal geo-mining condition.The essential consequence of abnormal surface subsidence at the border of subsidence basin is due to combininginteraction of groundwater and thick alluvial strata.The interrelation between soil compression values of aquifer strata and groundwater table drawdown presents parabolic incremental curve,nevertheless linear incremental curve appears for confined aquifers,and the deeper the waterhead,the larger the soil consolidation quantities.The predicted root mean square error is±8mm with 6.5% relative mean error when predicting alluvial strata consolidation at test site.Theoretical values are in agreement with measurement data obtained in the field.The set-up models can be reasonably used to predict and calculate soil consolidation induced by alluvium dewatering after underground coal extraction.
To study the mechanism of alluvial strata subsidence induced by coal extraction under the action of groundwater,surface settlement characteristics under thick alluvium overlaid condition were analyzed based on in-situ measurement data of three coal pits.Calculation models of soil compression were also developed for aquifer and confined water-bearing alluvial strata with the theory of effective stress.Moreover,the influence of alteration of groundwater table and soil mechanical parameters in alluvium strata on soil consolidation was discussed.Finally,the proposed models were analyzed and substantiated in accordance with field measurement data.The results indicate that extending scope caused by surface subsidence under thick water-bearing alluvium condition far exceeds that under normal geo-mining condition.The essential consequence of abnormal surface subsidence at the border of subsidence basin is due to combininginteraction of groundwater and thick alluvial strata.The interrelation between soil compression values of aquifer strata and groundwater table drawdown presents parabolic incremental curve,nevertheless linear incremental curve appears for confined aquifers,and the deeper the waterhead,the larger the soil consolidation quantities.The predicted root mean square error is±8mm with 6.5% relative mean error when predicting alluvial strata consolidation at test site.Theoretical values are in agreement with measurement data obtained in the field.The set-up models can be reasonably used to predict and calculate soil consolidation induced by alluvium dewatering after underground coal extraction.
引文
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[15]CARTER M,BENTLEY S P.Soil properties and their correlations(second edition)[M].London:Pentech Press,2016:74-106.
[16]WANG Binglong,XU Jialin,XUAN Dayang.Time function model of dynamic surface subsidence assessment of grout-injected overburden of a coal mine[J].International Journal of Rock Mechanics and Mining Sciences,2018(104):1-8.
[2]NEWMAN C,AGIOUTANTIS Z,LEON G B J.Assessment of potential impacts to surface and subsurface water bodies due to longwall mining[J].International Journal of Mining Science and Technology,2017(27):57-64.
[3]刘义新.厚松散层下深部开采覆岩破坏及地表移动规律研究[D].北京:中国矿业大学(北京)地球科学与测绘工程学院,2010:56-71.LIU Yixin.Overlying strata failure and surface movement evolution of deep mining with thick alluvium overlaid[D].Beijing:College of Geoscience and Surveying Engineering,China University of Mining&Technology,Beijing,2010:56-71.
[4]许延春,耿德庸,官云章,等.深厚含水松散层的工程特性及其在矿区中的应用[M].北京:煤炭工业出版社,2003:95-96.XU Yanchun,GENG Deyong,GUAN Yunzhang,et al.Engineering properties of thick alluvial strata and their applications in coal mining area[M].Beijing:China Coal Industrial Publishing Press,2003:95-96.
[5]BOOTH C J.Groundwater as an environmental constraint of longwall coal mining[J].Environmental Geology,2006,49(6):796-803.
[6]LOUPASAKIS C,ANGELITSA V,ROZOS D,et al.Mining geohazards-land subsidence caused by the dewatering of opencast coal mines:The case study of the Amyntaio coal mine,Florina,Greece[J].Natural Hazards,2014,70(1):675-691.
[7]郝延锦,吴立新,胡金星.厚松散层条件下地表移动变形预计理论研究[J].矿山测量,2000(2):25-26.HAO Yanjin,WU Lixin,HU Jinxing.Prediction theory of surface movement and deformation under thick unconsolidated strata[J].Mine Surveying,2000(2):25-26.
[8]韩奎峰,康建荣.厚冲积层矿区概率积分法预计修正模型研究[J].湖北农业科学,2009,48(12):3003-3006.HAN Kuifeng,KANG Jianrong.Research on prediction model caused by probability integration method in mining area under thick alluvial[J].Hubei Agricultural Sciences,2009,48(12):3003-3006.
[9]胡炳南,张华兴,申宝宏.建筑物、水体、铁路及主要井巷煤柱留设与压煤开采指南[M].北京:煤炭工业出版社,2017:55-56.HU Bingnan,ZHANG Huaxing,SHEN Baohong.Guide for coal pillar retention and coal mining under buildings,water bodies,railways and main roadways[M].Beijing:China Coal Industrial Publishing Press,2017:55-56.
[10]赵成刚,白冰,王运霞.土力学原理(修订版)[M].北京:清华大学出版社,2009:137-139.ZHAO Chenggang,BAI Bing,WANG Yunxia.Principle of soilmechanics(revised edition)[M].Beijing:Tsinghua University Press,2009:137-139.
[11]刘宝琛,阳军生,张家生.露天开挖及疏水引起的地面沉降及变形[J].煤炭学报,1999,24(1):39-42.LIU Baochen,YANG Junsheng,ZHANG Jiasheng.Surface subsidence and deformation caused by open pit mining and dewatering[J].Journal of China Coal Society,1999,24(1):39-42.
[12]汤伏全,夏玉成,姚顽强.黄土覆盖区开采沉陷及其地面保护[M].北京:科学出版社,2011:143-147.TANG Fuquan,XIA Yucheng,YAO Wanqiang.Mining subsidence and ground control under loess cover[M].Beijing:Science Publishing Press,2011:143-147.
[13]KRATZSCH H.Ming subsidence engineering[M].Berlin:Springer-Verlag,1983:400-401.
[14]薛禹群,吴吉春.地下水动力学(第三版)[M].北京:地质出版社,2011:47-49.XUE Yuqun,WU Jichun.Groundwater kinetics(third edition)[M].Beijing:Geological Publishing Press,2011:47-49.
[15]CARTER M,BENTLEY S P.Soil properties and their correlations(second edition)[M].London:Pentech Press,2016:74-106.
[16]WANG Binglong,XU Jialin,XUAN Dayang.Time function model of dynamic surface subsidence assessment of grout-injected overburden of a coal mine[J].International Journal of Rock Mechanics and Mining Sciences,2018(104):1-8.