采用马尔可夫链方法,定量分析坝基地层沉积旋回特征,得到坝基软弱夹层的发育特点及沉积规律,并将其分为3类Ⅰ岩块岩屑型、Ⅱ岩屑夹泥型、Ⅲ1泥夹岩屑型和Ⅲ2全泥型。结果表明Ⅰ类夹层多形成于洪泛盆地沉积的厚层黏土岩中或厚层黏土岩与厚层粉砂岩的交界处;Ⅱ类夹层一般在软岩内部发育,顶底部均为岩质相对较硬的粉砂岩或砂岩;Ⅲ类夹层主要形成于黏土质粉砂岩与黏土岩薄互层的半韵律沉积中,分布较稳定。室内慢剪试验获得性状最差的泥化夹层在饱水状态下的摩擦因数为0.223,按规范用粒度成分定量指标选取的夹层强度参数明显偏低,相当于接近液限状态时室内剪切峰值强度的0.72～0.86倍,最终类比其他相似地质条件下的工程经验,提出各类软弱夹层强度参数建议值。
Abstract
Weak intercalations, which are composed of clastic rocks, are widely distributed in Upper Jurassic red strata in Sichuan Basin. Due to the high clay content and low shear strength, these weak intercalations are prone to cause shear failure which leads to instability of the dam foundation of Xiaonanhai Project. Markov chain analysis is applied to the stratigraphic succession in order to point out any depositional regularity of the weak intercalations. In consideration of the grain size, mudding degree and structure characteristics, the weak intercalations are divided into three types (Ⅰ) cracked rock; (Ⅱ) cracked rock with mud interbedded; (Ⅲ) mudstone with cracked rock interbedded, or mudstone. Type Ⅰ mainly exists in the thick mudstone, which is attributed to the flood basin sub-facies, or develops at the junction of thick mudstone and siltstone. Such weak intercalations cannot extend long distance. Type Ⅱ generally lies in the soft rock and suffers more shear force owing to tectonic activities, a sheet of mud with scratches is common on the top and bottom. Type Ⅲ frequently appears in the second semi-rhythmic structure. Slow shear test reveals that the lowest strength parameter of weak intercalations is 0.223, and the value of strength parameter according to the quantified index of granularity composition is 0.72 to 0.86 times of that obtained from the slow shear test. In addition, recommended values of typical weak intercalations were given by considering other similar engineering experience.
关键词
小南海水电站 /
马尔可夫链 /
软弱夹层 /
沉积规律 /
强度参数
Key words
Xiaonanhai Project /
Markov chain /
weak intercalation /
depositional regularity /
strength parameter
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参考文献
[1] 王子忠. 四川盆地红层岩体主要水利水电工程地质问题系统研究[D]. 成都: 成都理工大学, 2011.(WANG Zi-zhong. Systematic Researches on Red Bed Rock Mass Engineering Geological problems of Water Resources and Hydropower Projects in Sichuan Basin, China[D]. Chengdu: Chengdu University of Technology, 2011.(in Chinese))
[2] 徐瑞春,周建军. 红层与大坝[M]. 武汉:中国地质大学出版社, 2010. (XU Rui-chun, ZHOU Jian-jun. Red Bed and Dam[M]. Wuhan: China University of Geosciences Press, 2010.(in Chinese))
[3] 胡 涛,任光明,聂德新,等. 沉积型软弱夹层成因分类及强度特征[J]. 中国地质灾害与防治学报, 2004,15(1):124-128. (HU Tao, REN Guang-ming, NIE De-xin, et al. Strength Characteristics with Genesis and Type of the Sedimentary Weak Intercalated Layers[J]. The Chinese Journal of Geological Hazard and Control, 2004, 15(1):124-128.(in Chinese))
[4] 宋自成,郑德顺,李明龙,等. 济源盆地中侏罗统马凹组沉积环境演化及其控制因素分析[J]. 河南理工大学学报(自然科学版), 2012, 31(5):543-550. (SONG Zi-cheng, ZHENG De-shun, LI Ming-long, et al. Analysis on the Evolution of Sedimentary Environments and Its Controlling Factors of the Middle Jurassic Ma’ao Formation in Jiyuan Basin[J]. Journal of Henan Polytechnic University (Natural Science),2012,31(5):543-550.(in Chinese))
[5] YE M, KHALEEL R. A Markov Chain Model for Characterizing Medium Heterogeneity and Sediment Layering Structure[J]. Water Resources Research, 2008, 44(9):1-15.
[6] SUMMER E J, TALLING P J, AMY L A, et al. Facies Architecture of Individual Basin-Plain Turbidities: Comparison with Existing Models and Implications for Flow Processes[J]. Sedimentology,2012, 59(6):1850-1887.
[7] CHARVIN K, GALLAGHER K, HAMPSON G L, et al. A Bayesian Approach to Inverse Modelling of Stratigraphy, Part 1: Method[J]. Basin Research, 2009, 21(1):5-25.
[8] VERWER K, PORTA G D, OSCAR M T, et al. Controls and Predictability of Carbonate Facies Architecture in a Lower Jurassic Three-Dimensional Barrier-Shoal Complex (Djebel Bou Dahar, High Atlas, Morocco)[J]. Sedimentology, 2009, 56(6):1801-1831.
[9] CHUTKO K J, LAMOUREUX S F. Biolaminated Sedimentation in a High Arctic Freshwater Lake[J]. Sedimentology, 2009, 56(6):1642-1654.
[10]张成凤. 马尔科夫链模拟在济阳坳陷中的应用[D]. 青岛:中国石油大学, 2010. (ZHANG Cheng-feng. Application of Markov Chain Simulation in the Jiyang Depression[D]. Qingdao: China University of Petroleum, 2010.(in Chinese))
[11]贺里尧,董兰凤,穆 鹏. 坝基岩体软弱层带力学参数[J].兰州大学学报(自然科学版), 2009, 45(增1):76-79. (HE Li-yao, DONG Lan-feng, MU Peng. Mechanical Parameters of Weak Interlayer of Dam Foundation Rock mass[J]. Journal of Lanzhou University (Natural Sciences), 2009, 45(Sup.1):76-79.(in Chinese))
[12]闫汝华,樊卫花. 马家岩水库坝基软弱夹层剪切特征及强度[J]. 岩石力学与工程学报, 2004, 23(22):3761-3764. (YAN Ru-hua, FAN Wei-hua. Shear Properties and Strength of Weak Intercalated Layers in Dam Foundation of Majiayan Reservoir[J]. Chinese Journal of Rock Mechanics and Engineering, 2004, 23(22):3761-3764.(in Chinese))
[13]朱筱敏. 沉积岩石学[M]. 北京: 石油工业出版社,2008. (ZHU Xiao-min. Sedimentary Petrology[M]. Beijing: Petroleum Industry Press, 2008.(in Chinese))
[14]唐良琴,刘东燕,聂德新. 软弱夹层力学参数取值规范分析[J]. 重庆大学学报, 2011, 34(12):35-41. (TANG Liang-qin, LIU Dong-yan, NIE De-xin. Discussion on Values Criterion of Strength Parameters of Weak Intercalations[J]. Journal of Chongqing University, 2011, 34(12):35-41.(in Chinese))
[15]马国彦,高广礼. 黄河小浪底坝区泥化夹层分布及其抗剪试验方法的分析[J]. 工程地质学报,2000,8(1):94-98.(MA Guo-yan, GAO Guang-li. Distribution of the Clay Intercalation in the Xiaolangdi Dam and Experimental Method of Shear Strength[J]. Journal of Engineering Geology, 2000, 8(1):94-98.(in Chinese))
[16]余先华,聂德新, 周洪福. 大型直剪与小型直剪对软弱夹层强度测试参数取值关系研究[J]. 工程地质学报, 2006, 14(增1):126-129. (YU Xian-hua, NIE De-xin, ZHOU Hong-fu. Study on Strength Parameters of Soft Interlayer for Large and Small Direct Shears[J]. Journal of Engineering Geology, 2006, 14(Sup.1):126-129.(in Chinese))
[17]DL5108—1999,混凝土重力坝设计规范[S]. 北京:电子工业出版社,2000.(DL5108—1999,Design Specification for Concrete Gravity Dam[S]. Beijing:Publishing House of Electronics Industry,2000.(in Chinese))
基金
国家自然科学基金资助项目(41272308)
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