Stability Analysis of Tailings Dam Based on Coupling Seepage and Stress

Transcription

1 2016 Internatonal Conference on Archtectural Engneerng and Cvl Engneerng (AECE-16) Stablty Analy of Talng Dam Baed on Couplng Seepage and Stre Lna ZHANG Cvl and Archtectural Engneerng Department Eat Chna Unverty of Technology Nanchang, Jangx, Chna e-mal: engchen LI Cvl and Archtectural Engneerng Department Eat Chna Unverty of Technology Nanchang, Jangx, Chna e-mal: Cde PENG Cvl and Archtectural Engneerng Department Eat Chna Unverty of Technology Nanchang, Jangx, Chna e-mal: Abtract Wth the hgh development of the mne enterpre n Chna, the cale of the talng' degn becomng bgger and bgger, the afety of the talng become more and more mportant. A one of the mot mportant part, the talng dam turn to be dater zone wth frequent accdent. Therefore, Talng Dam tablte partcularly mportant. Th paper baed on the theory of Seepage couplng and Stablty analy, takng the powerful non-lnearly fnte element oftware ABAQUS to make mulaton analy of talng dam, and comparatve analy wth the reult of clacal ultmate balance, the concludng part rae the propect of for tablty analy of talng dam. Conderng un-aturaton couplng between eepage and tre, the artcle buld two-dmenonal talng dam model, then mulate or compute t applyng ABAQUS. Stran-tre, dplacement, platcty and aturaton lne nephogram could be acqured by powerful graphcal pot-proceng module. The afety factor of the dam could be obtaned by trength reducton. Keyword-talng dam; couplng eepage and tre; lmt equlbrum ; ABAQUS; afety factor I. INTRODUCTION Talng dam [1] the mportant part of talng pond faclty, whch hdden huge ecurty danger and prone to caue accdent. Bede, the normal operaton of talng pond depend on the tablty of talng dam. Many erou mne accdent are parked off by the falure of talng dam project n the world, o the talng dam afety problem ha become the mot mportant component of the talng afety work [2]. So far the talng pond project uually mplfed talng dam a general lope or dam, ung clacal ultmate balance (ncludng lp crcle, Janbu, Bhop Method and o on). Though the prncple of clacal ultmate balance qute mple, obtaned reult lack of relable and reflect nuffcent nformaton. In the recent year, wth the development of computer technology, Numercal Smulaton Analy wdely ued n th feld, many reearch nttuton at home and abroad have developed numercal mulaton oftware (uch a ABQUS), whch conderng more factor (uch a eepage couplng, complex boundary). Through numercal mulaton oftware, the tablty coeffcent of the dam and other nformaton can be obtaned, a a gude to the degn and contructon of the talng dam project. II. ANALYSIS PRINCIPLES A. Seepage Couplng Theory The relatonhp between eepage feld and tre feld mutual nfluence and role [3]. On the one hand, the change of eepage force wll caue the change of eepage volume or hydrotatc preure, whch make the engneerng tructure or external load effectng geology body and tre feld to change; On the other hand, the change of tre feld caue tructure to occur deformaton, whch change t nternal poroty and permeablty coeffcent, thu change the flow feld. Under the eepage feld and tre feld nteracton, ultmately, t make the double feld to reach a table equlbrum, whch form a table eepage feld under teady tre and tre feld under the nfluence of eepage feld of nfluence, repectvely. gure 1. Couplng eepage and tre ketch B. Lmt Equlbrum Analy Lmt equlbrum analy a balanced analy by untable ol tatc, accordng to Mohr Coulomb crteron body lope tablty analy [4]. Copyrght 2017, the Author. Publhed by Atlant Pre. Th an open acce artcle under the CC BY-NC lcene ( 401

2 1) Sweden ldng : Swedh ldng law a lope tablty baed on Sweden crcular lp ntance raed by ellenu, whch conderng the ldng urface a contnuou crcular urface and the whole ldng earth a large rgd body [5]. The landlde dvded nto everal trp of ol, and gnore the force of ther own tran and column between the ndvdual lce. Therefore, Sweden ldng a mplfed lce, whch cannot meet all the tatc equlbrum condton, and the afety factor calculated to gve more trngent than other to be mall. A hown n gure2, the law generally baed on the analy of total tre, and afety factor defned a the entre ant-lde urface ldng urface lp torque and can provde all the lp rato of the torque. The equaton hown a (1). ( c l G co tg ) G n Where the afety factor or tablty factor c ol coheon, φ nternal frcton angle of ol, l the length of lde arc, G the weght of ol. (1) dvded nto everal trp of ol [7]. After any ldng urface dvded nto n ol column, aumpton pont of locaton alway the heght of the ol column at 3 pont. orce balance analy of each ol column performed, and ultmately the lope tablty factor obtaned. III. CASE ANALYSES A. Project Profle Accordng to the contructon tme and functon, the talng dam dvded nto ntal dam and pot dam. The dam foundaton a medum/lghtly weathered Phyllte (water nulaton coure), whch would be cleared before contructon. The ntegrty of rock ma better, what more, n t natural tate, t have good tablty. Both de of dam are lthologcal lope, and there are no gn of collape and lp, and good tablty n t natural tate. The dam heght 208 meter, the water level n the uptream reervor about 218 meter, and the overflow pont of downtream water level about 82 meter, o t would produce eepage force. Under the acton of teady eepage, the tablty of downtream face of dam (free urface) lghtly worened, o t need to make tablty analy of downtream dam lope. rom top to down, the dam compoed of four element: (1) ne and (2) Tal lty and, accordng to the mplfed homogeneou and layer to calculaton, the relatonhp between permeablty coeffcent and vod rato hown n TableⅠ, the relatonhp between pore preure and degree of aturaton hown n TableⅡ. TABLE I. THE PERMEABILITY COEICIENT CORRESPONDING WITH DIERENT PRESSURE AND POROSITY RATIO Preure (Kpa) gure 2. Swedh lce ketch 2) Bhop : Bhop lce aume ldng urface a an arc, whch regard landlde a a rgd body, conderng horzontal lateral force among lce, and aume that the coeffcent of tablty agant ldng bar at the bottom of each ol ldng urface are the ame [6]. Through analy the force balance, tablty coeffcent expreon a hown n Equaton (2). 1 ( cl Gtg ) m G n tg m co n 3) Janbu : Janbu aumed arbtrarly haped lp urface along the weak layer of the nterface, and the lder (2) Vod Rato Permeablty Coeffcent (10-6 m/) TABLE II THE RELATIONSHIP BETWEEN PORE PRESSURE AND SATURATION Pore Preure (KPa) Saturaton (3) Clay tone (ntal dam), the ldng urface wll not pa through th layer by prelmnary judgment, and the coheon and frcton angle hould be amplfed. (4) The rock ma of moderately weathered phyllte ha a good ntegrty, and t can be regarded a rgd body. B. The Stablty Analy of Bejng Lzheng Software Wthout conderng the effect of earthquake, baed on the Swedh lce, Janbu and Bhop, by ung lp crcle to calculate the afety factor of th talng dam n the condton of teady eepage, and th 402

3 Advance n Engneerng Reearch (AER), volume 72 come from Specfcaton for Degn of Rolled Earth Rock Dam (SL ), adoptng pecfy center and earch range or automatcally earch the mot dangerou lp urface to determne the ldng urface. Calculaton dagram hown n gure3. Safety factor ummary hown n Table Ⅲ. TABLE III. Steady Seepage Phae Non-earthquake gradually, that to ay, the matrx ucton gradually ncreaed. The aturaton lne fall n a curve, becaue of the permeablty of th ntal dam poor, the curve decreaed gnfcantly when t go through the ntal dam, and becaue of the hgh permeablty cuhon, the curve lope gradent. The downtream overflow pont over the dam toe about 15meter or o, th reult accordance wth the actual cae. SAETY ACTOR SUMMARY Safety actor Swedh lce Bhop Janbu gure 4. Contour plot of pore preure gure 3. Calculaton dagram C. The Analy of ABAQUS Seepage and Stablty At preent, the dam n teady eepage phae, accordng the above project profle to etablh model, on the ba of formula (3) to etup pore preure boundary of uptream dam lope, the bottom 2.5 meter thck and and gravel dranage layer whch permeablty coeffcent m/, the dam foundaton mpervou boundary, the type of meh element CPE4P (four node plane tran preure cell), accordng to the eepage and tre couplng prncple, th can etablh two dmenonal model of unaturated eepage flow by ung ABAQUS. Ph=146 (146-Yh) (3) Where Ph the lope water preure correpondng to the water level h, kpa, Yh the abolute elevaton correpondng to the water level h, m. When the Yh greater than 146, the water preure 146, whch ndcate that the water level above the water level lne zero. By applyng ABAQUS, t can be obtaned contour lne of pore preure (hown n gure 4) and aturaton contour (hown n gure 5). Accordng to the contour lne of pore preure, we can obtan the followng concluon, the dam nclude aturated eepage and unaturated eepage, and the dam nonaturated regon, whch ext negatve preure n t top rght corner, the other aturated regon. The reervor water from uptream to downtream and from aturated regon to unaturated regon. rom the aturaton contour, the red lne aturaton lne, and the below aturaton one hundred percent, and over th lne, the aturaton gradually decreae, correpondng negatve pore preure ncreaed gure 5. Saturaton contour plot Accordng to the project data, adoptng the ABAQUS to etablh two dmenonal lope analy model, on the ba of the platc zone development and the tran fled, and applyng trength reducton prncple, t can obtan the tablty factor of the talng dam. Tranformed feld varable V1, t can get the equvalent platc cloud mage of the dam n the condton of the dfferent reducton factor. When the reducton factor and t=0.7000, t would found more obvou through area, whch hown n the gure 6; when the reducton factor and t=0.7563, the platc cloud mage hown n gure7; when the reducton factor and t=0.7609, the platc mage hown n gure8.when the reducton factor 1.641, the dplacement contour hown n gure 9. gure 6. The platc mage (V1=1.550,t=0.7000) 403

4 fgure, from the gure10, we can get the afety factor gure 7. The platc mage (V1=1.634, t=0.7563) gure 8. The platc mage (V1=1.641, t=0.7690) gure 9. Dplacement contour mage (V1=1.641) rom the above mage, when the reducton factor and the tme , the dam wll produce the through platc zone n the upper rght, and the zone have larger dplacement, and the trend of crcular ldng urface wll comng oon, o the afety factor of th talng dam gure 10. The relatonhp between U1 and V1 Etablhng the vertex node pont et, and t would take the turnng pont of horzontal dplacement of the pont a the evaluaton crteron, the relatonhp between horzontal hft (U1) and reducton factor (V1) hown n the below IV. CONCLUSIONS AND PROSPECT rom the analy of Bejng LZheng lope oftware and ABAQUS oftware, the tablty factor of talng dam all meet the followng two tandard, the one that the mnmum afety factor of tablty agant ldng of the two tage talng dam accordng to the Sweden arc ldng calculaton (the tandard come from Techncal Specfcaton for Safety of Talng Pond) (AQ ); the another that the mnmum afety factor of the frt grade lope engneerng whch come from Specfcaton for Degn of Talng aclte n Mneral Proceng Plant. The tablty factor whch conder eepage couplng effect wll much afer, what more, applyng the trength reducton and ntegratng the platc zone and dplacement contour, the tablty factor have more relablty. Ung the ABAQUS oftware to mulate the talng dam, t would found the hape and poton of aturaton lne, the aturaton lne gradually decreae from uptream lope to downtream face of dam, when t go through the ntal dam, the lne dramatc declne, The downtream overflow pont over the dam toe about 15 meter or o, under th lne aturated flow, whle over th lne unaturated regon (negatve preure). rom the above we can know, the ABAQUS have an obvou advantage over the tablty analy of talng dam, the mulaton reult and the actual condton are dentcal wth each other, t can get abundant amount of nformaton, accordng to the montorng data, t can dynamc gan the afety condton of talng dam, t worth to ue and promote n the analy and evaluaton of talng dam project n the future. However, when ue th, t need more parameter, furthermore, t dffcult to chooe the conttutve and boundary, o t need more theoretcal reearch of cholar to make ure n the future. ACKNOWLEDGEMENT Th reearch wa upported by Natural Scence oundaton of Jangx Provnce (20141BDH80027, 20133BBE50032, 20141BBE50022 and KJLD13052), Scence and technology plannng project of Jangx Provncal Educaton Department (GJJ14496), Chna. REERENCES [1] Z.G.Teng, Analy and Evaluaton on Semc Stablty of Talng Dam. Hebe Metallurgy, 12(2001). [2] H.D. Xu, Stattcal Analy of Mne Talng Dam Accdent. Indutral Archtecture, 24(2001). [3] D. G. relund, J.Krahn, Comparon of lope tablty of analy.canadan Geotechncal Journal,14(1977). [4] D.Y. Zhu, Z.. L, M.S.Huang. Modfcaton to three well-known of lope tablty analy. Chnee Journal of Rock Mechanc and Engneerng, 2(2005). [5] X.P. Chen, P.Y. X, Z.S. Lang, et al. Couplng analy of heterogeneou earth dam tablty of eepage feld and tre feld. Rock and Sol Mechanc, 25(2004). 404

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