Influence of water level dropping rates on the collapse of karst soil caves
-
摘要: 水位升降引起的水气压力变化会导致岩溶土洞塌陷。通过开展物理模型试验与FLAC3D数值模拟相结合的方式，模拟相同供水速率不同排水速率下的水位升降波动对岩溶土洞的致塌过程，分析了水位升降波动过程中不同排水速率对既有土洞内水气压力的变化、覆盖层土压、变形的影响，建立了排水速率，覆盖层变形、塌陷与水气压力的关系，提出了水位波动对土洞塌陷的作用规律。结果表明：（1）排水速率对水气压力变化的影响规律基本一致但变化程度不同。水气压力的变化程度、响应时间与排水速率呈正相关。（2）覆盖层变形量、土压的变化与水气压力变化呈正相关，但影响程度不同，排水速率只是加快了其变化程度。（3）土洞变形、塌陷程度是综合因素所致。排水速率、水位波动次数对既有土洞中水气压力变化、以及土体变形效应均具有不同程度的影响。（4）数值模拟结果与试验室模型试验所得结论基本吻合。这些规律为进一步研究水动力因素对岩溶塌陷的作用规律提供了重要的理论支撑，为合理防治、预测岩溶塌陷提供了依据。
-
关键词:
- 土洞塌陷 /
- 物理模型试验 /
- FLAC3D数值模拟 /
- 排水速率 /
- 水位波动
Abstract: The change of water-gas pressure caused by the rise and fall of water level will lead to the collapse of karst soil caves. In this study, we combined the physical model test and FLAC3D numerical simulation to simulate the soil cave collapse caused by water level fluctuation under the same water supply rate and different drainage rates. Besides, we also analyzed the influence of different drainage rates on the variation of water-gas pressure, soil pressure of the overlying soil layer and deformation of soil caves during the fluctuation. We also established the relationship between water-gas pressure and variables such as drainage rates, overburden deformation and cave, and put forward the action law of water level fluctuations on the collapse of soil cave. The results show as follows. (1) The influence of drainage rates on the variation of water-gas pressure is basically the same, but with different degrees. The change degree and response time of water-gas pressure are positively correlated with the drainage rate. (2) The change of overburden deformation and soil pressure is positively correlated with the change of water-gas pressure, but with different influence degrees. The drainage rate can only accelerate the change degree. (3) Degrees of deformation and collapse of soil caves are caused by comprehensive factors. The speed of the drainage rate and the number of water level fluctuations influence the changes of water-gas pressure in different degrees in soil caves and also influence the soil deformation caused by water level fluctuations. (4) The numerical simulation results are basically consistent with the results of laboratory model test. These results provide important theoretical support for further research on the laws of hydrodynamic factors affecting karst collapse and provide a basis for rational prevention and prediction of karst collapse. -
图 3 模型装置及测量设备图（a）模型装置正面图（b）测量设备图（c）模型装置剖面图
Figure 3. Physical model device and monitoring equipment (a) front view of model device; (b) measurement equipment diagram; (c) profile view of model device
图 6 既有土洞上覆土体变形量与水气压力关系
Figure 6. Relationship between deformation of overlying soil and water-gas pressure of soil cave
图 7 排水速率为2.08×10−4 m·s−1土压随时间变化图
Figure 7. Variation of soil pressures with time at the drainage rate of 2.08×10−4 m·s−1
图 8 排水速率为4.17×10−4 m·s−1土压随时间变化
Figure 8. Variation of soil pressures with time at the drainage rate of 4.17×10−4 m·s−1
图 9 排水速率为4.17×10−3 m/s土压随时间变化
Figure 9. Variation of soil pressures with time at the drainage rate of 4.17×10−3 m·s−1
图 10 土压与水气压力关系图（水位上升）
Figure 10. Relationship between soil pressures and water-gas pressures when the water level rises
图 11 土压与水气压力关系图（水位下降）
Figure 11. Relationship between soil pressures and water-gas pressures when the water level drops
图 12 洞顶累计塌落量随水位波动次数的变化图
Figure 12. Variation of cumulative collapse volumes on the cave roof with the number of water level fluctuations
图 13 不同排水速率下塌陷口长短半轴长度变化图
Figure 13. Variation of the semi-axis lengths of the collapse opening under different drainage rates
图 14 排水速率为4.17×10−3 m·s−1时塌陷口半轴长度测量图；(a)长半轴测量图 (b)短半轴测量图
Figure 14. Measurement diagram of the semi-axis length of the collapse opening at the drainage rate of 4.17×10−3 m·s−1. (a) diagram of major half axis measurement; (b) diagram of short half axis measurement
图 15 不同排水速率下竖向位移分布图 (a)排水速率为2.08×10−4 m·s−1; (b)排水速率为2.78×10−4 m·s−1; (c)排水速率为4.17×10−4 m·s−1; (d)排水速率为8.34×10−4 m·s−1 ;(e)排水速率为4.17×10−3 m·s−1
Figure 15. Distribution of vertical displacements under different drainage rates (a) at the drainage rate of 2.08×10−4 m·s−1; (b) at the drainage rate of 2.78×10−4 m·s−1; (c) 4.17×10−4 m·s−1; (d) at the drainage rate of 8.34×10−4 m·s−1; (e) at the drainage rate of 4.17×10−3 m·s−1
图 16 不同排水速率下最大剪应力分布图 (a)排水速率为2.08×10−4 m·s−1; (b)排水速率为2.78×10−4 m·s−1; (c)排水速率为4.17×10−4 m·s−1; (d)排水速率为8.34×10−4 m·s−1 ; (e)排水速率为4.17×10−3 m·s−1
Figure 16. Distribution of maximum shear stresses under different drainage rates (a) at the drainage rate of 2.08×10−4 m·s−1; (b) at the drainage rate of 2.78×10−4 m·s−1; (c) at the drainage rate of 4.17×10−4 m·s−1; (d) at the drainage rate of 8.34×10−4 m·s−1; (e) at the drainage rate of 4.17×10−3 m·s−1
图 17 不同排水速率下塑性区分布图 (a)排水速率为2.08×10−4 m·s−1; (b)排水速率为2.78×10−4 m·s−1; (c)排水速率为4.17×10−4 m·s−1; (d)排水速率为8.34×10−4 m·s−1 ; (e)排水速率为4.17×10−3 m·s−1
Figure 17. Distribution of plastic zones under different drainage rates (a) at the drainage rate of 2.08×10−4 m·s−1; (b) at the drainage rate of 2.78×10−4 m·s−1; (c) at the drainage rate of 4.17×10−4 m·s−1; (d) at the drainage rate of 8.34×10−4 m·s−1; (e) at the drainage rate of 4.17×10−3 m·s−1
表 1 土体基本物理、力学参数
Table 1. Basic physical and mechanical parameters of soil
覆盖层类型 密度/g·cm−3 孔隙率 剪切模量/kpa 体积模量/kpa 内摩擦角/° 粘聚力/kPa 渗透系数/cm·s−1 红黏土 1.72 0.47 1.354×106 4.22×106 8.8 25.3 3.22×10−4 
下载: 导出CSV
表 2 覆盖层厚度与岩溶塌陷关系统计表
Table 2. Relationship between cover layer thickness and karst collapse
覆盖层厚度/m <2 2~4 4~6 6~8 8~10 10~12 12~14 合计 塌陷个数/个 97 72 69 56 22 2 1 318 占百分比/% 30.41 22.57 21.63 17.55 6.90 0.63 0.31 100
下载: 导出CSV
表 3 模型试验方案
Table 3. Model test scheme
方案 土洞直径/cm 初始水位位置 初始水位高度/mm 水位上升速率/m·s−1 水位下降速率/m·s−1 1 10 土层表面 100 2.78×10−4 4.17×10−3 2 4.17×10−4 3 2.08×10−4
下载: 导出CSV
表 4 不同排水速率下一次水位升降过程中水气压力响应、变化及初始环境温度效应
Table 4. Water-gas pressure response, variation and initial ambient temperature effect during one rise and fall process of water level under different drainage rates
排水速率/m·s−1 试验时环境初始温度/ ℃ 既有土洞内初始气压值/kPa 水气压力响应时间/s 水气压力消散历时/s 水气压力降幅/kPa 4.17×10−3 20.88 101.083 1 010 10 3.7233 4.17×10−4 25.85 99.065 1 260 80 1.1202 2.08×10−4 31.29 98.99 1 510 90 0.8505
下载: 导出CSV
-
[1] 李喜安, 黄润秋, 彭建兵, 陈志新. 关于物理潜蚀作用及其概念模型的讨论[J]. 工程地质学报, 2010, 18(6):880-886.LI Xi'an, HUANG Runqiu, PENG Jianbing, CHEN Zhixin. Establishment of conceptual models of physical sub-ground erosion[J]. Journal of Engineering Geology, 2010, 18(6): 880-886. [2] 罗小杰, 罗程. 岩溶地面塌陷三机理理论及其应用[J]. 中国岩溶, 2021, 40(2):171-188.LUO Xiaojie, LUO Cheng. Three-Mechanism Theory (TMT) of karst ground collapse and its application[J]. Carsologica Sinica, 2021, 40(2): 171-188. [3] 王建秀, 杨立中, 何静. 岩溶塌陷演化过程中的水-土-岩相互作用分析[J]. 西南交通大学学报, 2001, 36(3):314-317.WANG Jianxiu, YANG Lizhong, HE Jing. The coupling interaction of groundwater-soil-rock mass in karst collapse evolution[J]. Journal of Southwest Jiaotong University, 2001, 36(3): 314-314. [4] He K Q, Liu C L, Wang S J. Karst collapse related to over-pumping and a criterion for its stability[J]. Environmental Geology, 2003, 43(6): 720-724. [5] He K Q, Wang B, Zhou D Y. Mechanism and mechanical model of karst collapse in an over-pumping area[J]. Environmental Geology, 2004, 46(8): 1102-1107. doi: 10.1007/s00254-004-1099-8 [6] Guo R J, Chen X J, Tang L M, Zhang X C. Study on ground collapse of covered karst soil caves by sudden drop of groundwater[J]. Advances in Civil Engineering, 2021, 2021: 7796401. [7] 郭锐剑, 陈学军, 段建, 唐灵明, 张晓宸. 考虑空间形状的覆盖型岩溶土洞降水致陷分析[J]. 西南交通大学学报, 2023, 58(2):453-461.GUO Ruijian, CHEN Xuejun, DUAN Jian, TANG Lingming, ZHANG Xiaochen. Study on precipitation-induced subsidence of covered karst soil caves regarding spatial shape[J]. Journal of Southwest Jiaotong University, 2023, 58(2): 453-461. [8] 陈学军, 周明芳, 陈富坚, 肖明贵. 岩溶地区破坏性抽水致塌试验研究:以广西桂林西城区为例[J]. 地质科技情报, 2002, 21(1):79-82.CHEN Xuejun, ZHOU Mingfang, CHEN Fujian, XIAO Minggui. Destructive pumping test to study the characteristics of karst collapses in limestone region: A case study in the western urban area of Guilin City[J]. Geological Science and Technology Information, 2002, 21(1): 79-82. [9] Jiang X Z, Lei M T, Gao Y L. Formation mechanism of large sinkhole collapses in Laibin, Guangxi, China[J]. Environment Earth Sciences, 2017, 76(24): 810-823. [10] Jia L, Li L J, Meng Y, Wu Y B, Pan Z Y, Yin R C. Responses of cover-collapse sinkholes to groundwater changes: A case study of early warning of soil cave and sinkhole activity on Datansha island in Guangzhou, China[J]. Environmental Earth Sciences, 2018, 77(13): 1-11. [11] 沈佳, 简文彬, 苏添金, 洪儒宝, 张少波. 岩溶区土洞塌陷演化过程研究:以龙岩市樟坑自然村土洞塌陷为例[J]. 水利与建筑工程学报, 2020, 18(3):1-8, 64. doi: 10.3969/j.issn.1672-1144.2020.03.001SHEN Jia, JIAN Wenbin, SU Tianjin, HONG Rubao, ZHANG Shaobo. Soil cave collapse process in karst area: A case study of soil cave collapse in Zhangkeng natural village, Longyan[J]. Journal of Water Resources and Architectural Engineering, 2020, 18(3): 1-8, 64. doi: 10.3969/j.issn.1672-1144.2020.03.001 [12] Shi H, Li Q M, Zhang Q L, Yu Y Z, Xing Y J, Yu Kun. Mechanism of shallow soil cave–type karst collapse induced by water inrush in underground engineering construction[J]. Journal of Performance of Constructed Facilities, 2020, 34(1): 1-8. [13] 雷明堂, 蒋小珍, 李瑜. 岩溶塌陷模型试验:以武昌为例[J]. 地质灾害与环境保护, 1993, 4(2):39-44. [14] Xiao X X, Xu M, Ding Q Z, Kang X B, Xia Q, Du F. Experimental study investigating deformation behavior in land overlying a karst cave caused by groundwater level changes[J]. Environment Earth Sciences, 2018, 77(3): 64-77. doi: 10.1007/s12665-017-7102-y [15] Xiao X X, Gutiérrez F, Guerrero J. The impact of groundwater drawdown and vacuum pressure on sinkhole development, physical aboratory models[J]. Geology, 2020, 279: 1-10. [16] 张鑫. 覆盖型岩溶塌陷模型试验与数值模拟研究[D]. 合肥:合肥工业大学, 2017.ZHANG Xin. Model test and numerical simulation of overburden karst collapse[D]. Hefei: Hefei University of Technology, 2017. [17] 张少波, 简文彬, 洪儒宝, 黄鹏, 陈鸿志, 刘奔. 水位波动条件下覆盖型岩溶塌陷试验研究[J]. 工程地质学报, 2019, 27(3):659-667.ZHANG Shaobo, JIAN Wenbin, HONG Rubao, HUANG Peng, CHEN Hongzhi, LIU Ben. Experimental study on collapse of covered karst under water-level fluctuation[J]. Journal of Engineering Geology, 2019, 27(3): 659-667. [18] 洪儒宝, 简文彬, 陈雪珍. 覆盖型岩溶土洞对地下水升降作用的响应及其塌陷演化过程研究[J]. 工程地质学报, 2023, 31(1):240-247.HONG Rubao, JIAN Wenbin, CHEN Xuezhen. Study on the response of covered karst soil cave to groundwater fluctuation and its collapse evolution process[J]. Journal of Engineering Geology, 2023, 31(1): 240-247. [19] Lin H, Liu T Y, Li J T, Cao P. A simple generation technique of complex geotechnical computational model[J]. Mathematical Problems in Engineering, 2013, 2013: 1-8. [20] Liu H L, Li L C, Li Z C, Yu G F. Numerical modelling of mining-induced inrushes from subjacent water conducting karst collapse columns in Northern China[J]. Mine Water and the Environment, 2018, 37(4): 652-662. doi: 10.1007/s10230-017-0503-z [21] 邢宇健. 岩溶区地下水位动态变化诱发地表塌陷的机理研究[D]. 北京:北京交通大学, 2018.XING Yujian. Study on the mechanism of overburden collapse induced by groundwater fluctuation in karst area[D]. Beijing: Beijing Jiaotong University, 2018. [22] 熊启华, 高旭, 徐庆, 王芮琼, 李祖春, 陶良. 覆盖型岩溶塌陷动态演化数值模型研究[J]. 安全与环境工程, 2022, 29(1):85-92.XIONG Qihua, GAO Xu, XU Qing, WANG Ruiqiong, LI Zuchun, TAO Liang. Dynamic evolution numerical model of cover-collapse sinkholes[J]. Safety and Environmental Engineering, 2022, 29(1): 85-92. [23] 熊启华, 高旭, 涂婧, 王芮琼, 晏鄂川, 李祖春. 负压作用下土洞型岩溶塌陷机理及力学模型研究[J]. 人民长江, 2022, 53(9):163-168, 180.XIONG Qihua, GAO Xu, TU Jing, WANG Ruiqiong, YAN E'chuan, LI Zuchun. Mechanism of soil-cave type karst collapse under negative pressure and its mechanical model[J]. Yangtze River, 2022, 53(9): 163-168, 180. [24] 薛明明, 陈学军, 宋宇, 高晓彤, 李辉, 甘小卉, 张铭致, 潘宗源, 唐灵明. 基于FLAC3D不同降雨速率下土洞致塌规律研究[J]. 中国岩溶, 2022, 41(6):905-914.XUE Mingming, CHEN Xuejun, SONG Yu, GAO Xiaotong, LI Hui, GAN Xiaohui, ZHANG Mingzhi, PAN Zongyuan, TANG Lingming. A study on collapse law of soil cave with different rainfall rates based on FLAC3D[J]. Carsologica Sinica, 2022, 41(6): 905-914. [25] Fumagalli E. Model simulation of rock mechanics problem. rock mechanics in engineering practice[M]. London, J. Wiley Bulletin Ismes Nr. 38, 1968: 46-78. [26] 贾龙, 蒙彦, 管振德. 岩溶土洞演化及其数值模拟分析[J]. 中国岩溶, 2014, 33(3):294-298.JIA Long, MENG Yan, GUAN Zhende. Evolution and numerical simulation of a karst soil cave[J]. Carsologica Sinica, 2014, 33(3): 294-298. -
点击查看大图
计量
- 文章访问数: 34
- HTML浏览量: 4
- PDF下载量: 12
- 被引次数: 0
