Loess joints are the places where groundwater exists and migrates. They break the soil, and affect the stability and strength of loess, causing enormous losses on both economy and human lives. Joints are the structural basis of all kinds of loess disasters. Accurate analysis of its development characteristics and distribution rules is crucial to understanding the frequent occurrence of loess disasters. Through systematic field investigation, mathematical statistics and topological analysis of loess in Longxi, we found that: (1) The dominant strikes of loess tectonic joints in Longxi are NNW,NWW and NE, which is influenced by strike-slip fault and reverse tilting fault.(2) The occurrence of dominant tectonic joints group obeys the Gaussian normal distribution, with the dip angle mostly within 60-80°. The occurrence of vertical joints are more randomly distributed and highly discrete. (3) The average spacing of both tectonic and vertical joints is wide, the opening of joints belongs to “crack” in standard, and the continuity medium, except that the spacing of vertical joints is more concentrated, while the opening of tectonic joints is smaller by comparison. (4) Topological analysis shows that I-node is the majority. Joints extension process is easily interrupted. Branch ratio is at a low level below 3. Topological analysis is more simple and intuitive to describe connectivity, especially under the help of powerful toolbox in software, and has been discussed for decades in the world, yet is rarely used in relative research in China. The research results provide basic data for the recovery of Neotectonics stress fields, for understanding the basic laws of joints development and the numerical modeling of joints network.
Key words
loess /
joints /
geometrical features /
topological analysis /
connectivity
{{custom_sec.title}}
{{custom_sec.title}}
{{custom_sec.content}}
References
[1] 彭建兵, 林鸿州, 王启耀, 等. 黄土地质灾害研究中的关键问题与创新思路[J]. 工程地质学报, 2014, 22(4): 684-691.
[2] 王景明, 倪玉兰, 孙建中. 黄土构造节理研究及其应用[J]. 工程地质学报, 1994(4): 31-42.
[3] 雷光伟, 杨春和, 王贵宾, 等. 北山预选区新场地段岩体节理几何特征及评价[J]. 岩石力学与工程学报, 2016, 35(5): 896-905.
[4] 骆 进, 项 伟, 吴云刚, 等. 陕北黄土垂直节理形成机理的试验研究[J]. 长江科学院院报, 2010, 27(3): 38-41.
[5] 王景明. 黄土构造节理的理论及其应用[M].北京:中国水利水电出版社, 1996.
[6] 李同录, 王 红, 付昱凯, 等. 黄土垂直节理形成机理的试验模拟[J]. 地球科学与环境学报, 2014, 36(2): 127-134.
[7] 王新刚, 胡 斌, 赵治海, 等. 渗流作用下节理型黄土开挖边坡塌滑破坏分析[J]. 自然灾害学报, 2014, 23(2): 47-52.
[8] 桂 洋, 夏才初, 钱 鑫, 等. 节理在初始接触状态下空腔分布的确定及应用[J]. 长江科学院院报, 2018, 35(3): 21-25.
[9] SANDERSON D J, NIXON C W. The Use of Topology in Fracture Network Characterization[J]. Journal of Structural Geology, 2015, 72: 55-66.
[10]HEALY D, RIZZO R E, CORNWELL D G, et al. FracPaQ: A MATLAB Toolbox for the Quantification of Fracture Patterns[J]. Journal of Structural Geology, 2017, 95: 1-16.
[11]丁宏伟, 李 莉, 姚兴荣, 等. 大气降水对黄土滑坡的影响和控制:以甘肃省陇西黄土高原为例[J]. 甘肃地质, 2013(1): 55-60.
[12]ISRM. International Society for Rock Mechanics Commission on Standardization of Laboratory and Field Tests: Suggested Methods for the Quantitative Description of Discontinuities in Rock Masses[J]. International Journal of Rock Mechanics & Mining Sciences & Geomechanics Abstracts, 1978, 15(6): 319-368.
[13]刘冲平, 郝文忠, 王吉亮, 等. 顺坡向外倾优势裂隙连通率对高边坡稳定性影响分析[J]. 长江科学院院报, 2014, 31(12): 74-77.
[14]緒方正虔. 岩盤分類の要因としての岩盤の不連続面, 岩盤分類[J]. 応用地質, 1984(1):12-18.
[15]黄国明,黄润秋.用窗口法估计不连续面的连通率[J].水文地质工程地质,1998(6):3-5.
[16]JING L, STEPHANSSON O. Network Topology and Homogenization of Fractured Rocks[M]∥JAMTVEIT B, YARDLEY B W D. Fluid Flow and Transport in Rocks: Mechanisms and effects. Dordrecht: Springer Netherlands, 1997: 191-202.
[17]MANZOCCHI T. The Connectivity of Two-dimensional Networks of Spatially Correlated Fractures: Connectivity of Two-dimensional Networks[J]. Water Resources Research, 2002, 38(9): 1-20.
[18]MAKEL H G. The Modelling of Fractured Reservoirs: Constraints and Potential for Fracture Network Geometry and Hydraulics Analysis[J]. Geological Society London Special Publications, 2007, 292(1): 375-403.
[19]RILEY M S. Fracture Trace Length and Number Distributions from Fracture Mapping[J]. Journal of Geophysical Research Solid Earth, 2005, 110(B8), doi: 10.1029/2004JB003164.
[20]卢全中, 彭建兵. 黄土体结构面的发育特征及其灾害效应[J]. 西安科技大学学报, 2006, 26(4): 446-450.
[21]周 喻, 张怀静, 吴顺川, 等. 节理连通率对岩体力学特性影响的细观研究[J].岩土力学, 2015.
PDF(6309 KB)
