Advances in seismic design of earth-rockfill dams and foundations in China and revision of code based on lessons from Wenchuan Earthquake
LIU Xiao-sheng, ZHAO Jian-ming, YANG Yu-sheng, WANG Zhong-ning, YANG Zheng-quan, LIU Qi-wang, CHEN Ning
1. State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing 100048, China; 2. Engineering Research Center on Anti-Earthquake and Emergency Support Techniques of Hydropower Projects, Ministry of Water Resources, Beijing 100048, China
Abstract:The advances in seismic design of earth-rockfill dams and foundations and the revision of code for seismic design of hydraulic structures in China (SL203-97/DL5073-2000) are presented based on research results and lessons from Wenchuan Earthquake disasters. The main revisions and advances focus on four aspects: (1) Seismic fortification criterion and its basic principles, in which the seismic design criterion, design parameters of ground motions and method for determining seismic waves are revised. For especially important projects, the seismic safety margins of the structures under MCE shall be assessed in order to prevent any collapse resulting in reservoir water discharging catastrophically. The near-field effect, hanging wall effect and unsteadiness of the frequency spectrum shall be considered when determining the design earthquake response spectrum. Earthquake prevention and disaster mitigation emergency contingency plans are required for the structures with engineering seismic fortification category of Class A. The seismic response spectrum for earth-rockfill dams is stipulated, and the value of the maximum acceleration response spectrum ( ) is taken as 1.60, whose corresponding damping ratio is 20%. (2) Site and foundation, in which the criterion for classification of site soils and site itself are revised. Site soils are classified into 5 types instead of 4 types in the old code according to the shear wave velocity of soil layer, and are classified in more detail than before according to the type of site soil and overburden thickness. For the liquefaction potential evaluation method, the formula for determining the critical standard penetration test N-values (SPT N-values) and the formula for correcting the influence of the effective overburden stress on SPT N-values are revised. (3) Seismic calculation and safety evaluation of earth-rockfill dams, in which contents for seismic calculation are supplemented. Seismic calculation should include seismic stability calculation, permanent deformation calculation, safety evaluation of the anti-seepage body and liquefaction potential evaluation. The scope for adopting the dynamic analysis method for the analysis of seismic effect and safety evaluation is supplemented. For the earth-rockfill dams with the following conditions: a) higher than 150 m and with a design intensity of VII; b) higher than 70 m and with a design intensity of Ⅷ or Ⅸ; and c) presence of liquefiable soils in the foundation based on finite element method is necessary for dynamic analysis to comprehensively evaluate its seismic stability. For the earth-rockfill dams with deposits thicker than 40 m, finite element dynamic analysis is recommended, and the principles for dynamic analysis of earth-rockfill dams are provided, including selection of constitutive model and determination of model parameters, calculation of the permanent deformation and requirement for stability analysis. The basic principles for evaluating seismic safety of earth-rockfill dams according to the dynamic results are provided. (4) Earthquake resistant measures for earth-rockfill dams and foundations, in which earthquake resistant measures for CFRD are proposed according to the experience of the design, construction and lessons from earthquake damages of Zipingpu Dam in Wenchuan Earthquake, including seismic deformation control, protection of dam crest and nearby slope, anti-squeezing of vertical joints, anti-dislocation of horizontal construction joints and detailed structure design of joints.
刘小生, 赵剑明, 杨玉生, 王钟宁, 杨正权, 刘启旺, 陈宁. 基于汶川地震震害经验的土石坝抗震设计规范修编[J]. 岩土工程学报, 2015, 37(11): 2111-2118.
LIU Xiao-sheng, ZHAO Jian-ming, YANG Yu-sheng, WANG Zhong-ning, YANG Zheng-quan, LIU Qi-wang, CHEN Ning. Advances in seismic design of earth-rockfill dams and foundations in China and revision of code based on lessons from Wenchuan Earthquake. Chinese J. Geot. Eng., 2015, 37(11): 2111-2118.
[1] 陈厚群. 水工建筑物抗震设计规范修编的若干问题研究[J]. 水力发电学报, 2011, 30(6): 4-10. (CHEN Hou-qun. Study on some revision issues of aseismatic design codes of hydraulic structures in China[J]. Journal of Hydroelectric Engineering, 2011, 30(6): 4-10. (in Chinese)) [2] 陈厚群, 徐泽平, 李 敏. 汶川大地震和大坝抗震安全[J]. 水利学报, 2008, 39(10): 1158-1167. (CHEN Hou-qun, XU Ze-ping, LI Min. Wenchuan Earthquake and seismic safety of large dams[J]. Journal of Hydraulic Engineering, 2008, 39(10): 1158-1167. (in Chinese)) [3] 陈厚群. 汶川地震后对大坝抗震安全的思考[J]. 中国工程科学, 2009, 11(6): 44-53. (CHEN Hou-qun. Consideration on seismic safety of dams in China after the Wenchuan earthquake[J]. China Academic Journal, 2009, 11(6): 44-53. (in Chinese)) [4] 陈生水, 方绪顺, 钱亚俊. 高土石坝地震安全评价及抗震设计思考[J]. 水利水运工程学报, 2011(1): 17-21. (CHEN Sheng-shui, FANG Xu-shun, QIAN Ya-jun. Thoughts on safety assessment and earthquake-resistance for high earth-rock dams[J]. Hydro-science and Engineering, 2011(1): 17-21. (in Chinese)) [5] 朱 晟. 土石坝震害与抗震安全[J]. 水力发电学报, 2011, 30(6): 40-51. (ZHU Sheng. Earthquake damages and dam safety[J]. Hydroelectric Engineering, 2011, 30(6): 40-51. (in Chinese)) [6] 宋胜武, 蔡德文. 汶川大地震紫坪铺混凝土面板堆石坝震害现象与变形监测分析[J]. 岩石力学与工程学报, 2009, 28(4): 840-849. (SONG Sheng-wu, CAI De-wen. Earthquake damage phenomenon and deformation monitoring analysis for Zipingpu concrete faced rockfill dam during Wenchuan Earthquake[J]. Rock Mechanics and Engineering, 2009, 28(4): 840-849. (in Chinese)) [7] 陈生水, 霍家平, 章为民. “5•12” 汶川地震对紫坪铺混凝土面板坝的影响及原因分析[J]. 岩土工程学报, 2008, 30(6): 795-801. (CHEN Sheng-shui, HUO Jia-ping, ZHANG Wei-min. Analysis of effects of “5•12” Wenchuan earthquake on Zipingpu concrete face rock-fill dam[J]. Chinese Journal of Geotechnical Engineering, 2008, 30(6): 795-801. (in Chinese)) [8] 高希章, 陆恩施, 杨志宏, 等. 经历”5•12”汶川大地震的紫坪铺面板堆石坝[C]// “5•12 “汶川特大地震灾后重建学术交流会. 成都, 2009. (GAO Xi-zhang, LU En-shi, YANG Zhi-hong, et al. The Zipingpu rock fill dam undergone the “5•12” Wenchuan Earthquake[C]// Symposium on Reconstruction after "5•12" Wenchuan Earthquake. Chengdu, 2009. (in Chinese)) [9] 宋彦刚, 邓良胜, 王 昆, 等. 紫坪铺水库大坝震损及应急修复综述[J]. 四川水力发电, 2009, 28(2): 8-13. (SONG Yan-gang, DENG Liang-sheng, WANG Kun, et al. Seismic damages of Dam of Zipingpu Reservoir and emergency repairs[J]. Sichuan Water Power, 2009, 28(2): 8-13. (in Chinese)) [10] 孔宪京, 周 扬, 邹德高, 等. 汶川地震余震记录及紫坪铺面板堆石坝余震反应研究[J]. 岩土工程学报, 2011, 33(5): 673-678. (KONG Xianjing, ZHOU Yang, ZOU De-gao, et al. Aftershock records of Wenchuan Earthquake and seismic response of Zipingpu Concrete Face Rock-fill Dam[J]. Chinese Journal of Geotechnical Engineering, 2011, 33(5): 673-678. (in Chinese)) [11] 孔宪京, 邹德高, 周 扬, 等. 汶川地震中紫坪铺混凝土面板堆石坝震害分析[J]. 大连理工大学学报, 2009(5): 667-674. (KONG Xian-jing, ZOU De-gao, ZHOU Yang, et al. Earthquake damage analysis of Zipingpu concrete face rock-fill dam during Wenchuan earthquake[J]. Journal of Dalian University of Technology, 2009, 49(5): 667-674. (in Chinese)) [12] 赵剑明, 刘小生, 温彦锋, 等. 紫坪铺大坝汶川地震震害分析及高土石坝抗震减灾研究设想[J]. 水力发电, 2009(5): 11-14. (ZHAO Jian-ming, LIU Xiao-sheng, WEN Yan-feng, et al. Analysis of earthquake damage of the Zipingpu dam in Wenchuan earthquake and the study proposal on the anti-earthquake and disaster reduction of high earth-rock dam[J]. Water Power, 2009, 35(5): 11-14. (in Chinese)) [13] 赵剑明, 刘小生, 刘启旺, 等. 先期震动对土石坝地震永久变形的影响研究[J]. 世界地震工程, 2011, 27(1): 28-33. (ZHAO Jian-ming, LIU Xiao-sheng, LIU Qi-wang, et al. Study on the effect of pre-vibration on earthquake-induced permanent deformation of an earth-rock fill dam[J]. World Earthquake Engineering, 2011, 27(1): 28-33. (in Chinese)) [14] GUAN Z C. Investigation of the 5.12 Wenchuan earthquake damages to the Zipingpu water control project and an assessment of its safety state[J]. Science in China Series E: Technological Sciences, 2009, 52(4): 820-834. [15] ZHANG J M, YANG Z Y, GAO X Z, et al. Lessons from damages to high embankment dams in the May 12, 2008 Wenchuan earthquake[J]. ASCE Geotech Special Pub, 2010, 201: 1-31. [16] 朱 晟, 石高峰, 周建平. 碧口心墙堆石坝抗震复核分析[J]. 岩石力学与工程学报, 2011, 30(增刊1): 2954-2962. (ZHU Sheng, SHI Gao-feng, ZHOU Jian-ping. Analysis of seismic review of Bikou rockfill dam with earth core[J]. Chinese Journal of Rock Mechanics and Engineering, 2011, 30(S1): 2954-2962. (in Chinese)) [17] SL 203—97 水工建筑物抗震设计规范[S]. 1999 (SL 203—97 Specification of for seismic design of hydraulic structures[S]. 1999. (in Chinese)) [18] DL 5073—2000 水工建筑物抗震设计规范[S]. 2000. (DL 5073—2000 Specification of for seismic design of hydraulic structures[S]. 2000. (in Chinese)) [19] GB 50×××?××××. 水工建筑物抗震设计规范(送审稿) [S]. (GB 50×××?××××. Specifications for seismic design of hydraulic structures(Draft)[S]. (in Chinese)) [20] GB 50011—2010. 建筑抗震设计规范(S). (GB 50011—2010 Code for seismic design of buildings[S]. (in Chinese)) [21] GB 50487—2008 水利水电工程地质勘察规范[S]. 2008. (GB 50487—2008 Code for engineering geological investigation of water resources and hydropower[S]. 2008. (in Chinese)) [22] 刘小生, 赵剑明, 王钟宁, 等. 高土石坝抗震性能及抗震安全研究[R]. 北京: 中国水利水电科学研究院, 2011. (LIU Xiao-sheng, ZHAO Jian-ming, WANG Zhong-ning, et al. Research on seismic performance and seismic safety of high embankment dams[R]. Beijing: China Institute of Water Resource and Hydraulic Research, 2011. (in Chinese)) [23] 刘小生, 王钟宁, 汪小刚, 等. 面板坝大型振动台模型试验与动力分析[M]. 北京: 中国水利水电出版社, 2005: 40-41. (LIU Xiao-sheng, WANG Zhong-ning, WANG Xiao-gang, et al, Large scale table model tests and dynamic analysis of CFRD[M]. Beijing: China Water Power Press, 2005: 40-41. (in Chinese)) [24] 杨玉生, 刘小生, 赵剑明, 等. 土石坝坝体和地基液化分析方法与评价[J]. 水力发电学报, 2011, 30(6): 94-101. (YANG Yu-sheng, LIU Xiao-sheng, ZHAO Jian-ming, et al. Methods for liquefaction potential evaluation of embankment and foundation and discussion on these methods[J]. Journal of Hydroelectric Engineering, 2011, 30(6): 91-108. (in Chinese)) [25] 赵剑明, 刘小生, 陈 宁, 等. 高心墙堆石坝的极限抗震能力研究[J]. 水力发电学报, 2009, 28(5): 97-102. (ZHAO Jian-ming, LIU Xiao-sheng, CHEN Ning, et al. Research on the maximum anti-seismic capability of high earth core rock-fill dam[J]. Journal of Hydroelectric Engineering, 2009, 28(5): 97-102. (in Chinese)) [26] 杨玉生, 刘小生, 赵剑明, 等. 标准贯入击数的挖填方校正方法研究[J]. 水力发电学报, 2014, 33(1): 171-177. (YANG Yu-sheng, LIU Xiao-sheng, ZHAO Jian-ming, et al. Influence of excavation and filling on seismic liquefaction potential evaluation of foundation soils[J]. Journal of Hydroelectric Engineering, 2014, 33(1): 171-177. (in Chinese)) [27] 刘启旺, 杨玉生, 刘小生, 等. 标贯击数液化判别方法的比较[J]. 地震工程学报, 2015(已录用). (LIU Qi-wang, YANG Yu-sheng, LIU Xiao-sheng, et al. Comparison of standard penetration test(SPT) method for evaluating seismic liquefaction potential[J]. China Earthquake Engineering Journal, 2015(Accepted). (in Chinese))