-
摘要:
岩崩坡面撞击破碎是运动轨迹难以预测的重要原因, 其中坡体几何特征是影响破碎块体运动变化特征的关键因素。为了研究岩崩撞击破碎过程及坡体几何特征对岩崩块体运动特征的影响, 利用离散单元法(PFC2D)模拟技术, 通过统计典型岩崩灾害点岩体结构与坡体几何特征, 建立了岩崩自由落体-撞击破碎-运动堆积模型, 剖析了在不同坠落高度、撞击角度条件下岩崩坡面撞击碎裂过程, 获得了块体运动速度、裂纹数量和冲击力变化曲线, 同时采用双参数Weibull分布对碎裂块体破碎程度进行了描述。实验结果表明: 破裂过程分为接触-解体、挤压-碎裂及独立运动3个阶段; 岩体碎裂由撞击点开始, 沿结构面先出现解体, 再产生新断裂面的岩石破碎; 块体速度、裂纹数量和冲击力的骤变均发生在接触-解体与挤压-碎裂阶段, 块体速度骤降, 呈现出"阶梯效应", 冲击力骤升, 表现为"双峰现象", 同时随着坠落高度增加或撞击角度减小, "阶梯效应"与"双峰现象"更为明显; 同一撞击角度条件下, 坠落高度的增加使得撞击动能增加, 进而增大了破碎程度, 导致粒径分布范围与特征粒径尺寸的减小; 同一坠落高度下, 撞击角度的增加, 意味着接触面积的减小, 进而降低了破碎程度, 导致粒径分布范围与特征粒径尺寸的增大。研究成果对揭示岩崩坡面撞击碎裂机理及预测块体运动轨迹提供了技术支撑。
Abstract:Objective The impact and fracture of rockfall are important reasons for the difficulty in predicting movement trajectories, and the geometric characteristics of slope bodies are key factors affecting the movement.
Methods To study the crushing process of rockfalls and the influence of slope geometry characteristics on the movement of rockfall blocks, discrete element method (PFC2D) simulation technology was used to establish a rockfall free-fall-impact model to analysethe rock mass structure and slope geometry characteristics of typical rockfall disaster points. The fragmentation process of rockfall under different fall heights and impact angles is analysed, and the block motion velocity, crack number and impact force are obtained. Moreover, the two-parameter Weibull distribution is used to describe the fragmentation degree of blocks.
Results The experimental results reveal that the fracture process can be divided into three stages: Contact-disintegration, extrusion-fragmentation and independent movement. Rock mass fragmentation starts at the impact point, disintegration occurs along the structural plane first, and fragmentation occurs on the new fracture plane. Sudden changes of the block velocity, crack quantity and impact force occur in the contact-disintegration and compression-fragmentation stages. The block velocity plummets, exhibiting a "step effect", and the impact force rises sharply, revealing a "double peak phenomenon". Moreover, when the fall height increases or the impact angle decreases, the "step effect" and "double peak phenomenon" become more obvious. Under the same impact angle, an increase of the fall height results in the increase of impact kinetic energy, thus increasing the degree of fragmentation and decreasing the particle size distribution range and characteristic particle size. At the same fall height, an increase in the impact angle causes that the contact area is reduced, and the degree of breakage is reduced, increasing the particle size distribution range and characteristic particle size.
Conclusion The present results provide technical support for revealing the impact fragmentation mechanism of rockfall slopes and predicting the trajectory of block motion.
-
Key words:
- rockfall /
- dynamic fragmentation /
- discrete element method(DEM) /
- Weibull distribution /
- slope impact
-
图 1 岩崩坡面撞击碎裂过程示意图
Figure 1. Diagram of the rockfall fragmentation process upon slope impact
图 4 岩体坡面撞击碎裂过程数值模型
a.坡中坡度30°；b.坡中坡度45°；c.坡中坡度60°
Figure 4. Numerical model of rockfall fragmentation process upon slope impact
图 5 灰岩静态单轴压缩应力-应变曲线
Figure 5. Stress-strain curves for limestone under static uniaxial compression
图 6 岩崩坡面撞击碎裂过程
a.岩体撞击前; b.岩体沿着层面破碎; c.岩体沿节理破碎; d.碎裂块体相互挤压
Figure 6. Rockfall fragmentation process upon slope impact
图 7 岩体速度、裂纹数量、冲击力随时间变化曲线
Figure 7. Curves of rock mass velocity, number of cracks, and ground impact force over time
图 8 不同坠落高度下岩体速度、裂纹数量、地面冲击力随时间变化曲线
Figure 8. Curves of the rock mass velocity, crack number and impact force under the different heights
图 9 不同撞击面坡度下岩体速度、裂纹数量、地面冲击力随时间变化曲线
Figure 9. Curves of the rock mass velocity, crack number and impact force under different impact angles
图 11 不同条件下Weibull分布函数拟合直线
Figure 11. Fitting resluts through Weibull distribution function under different conditions
图 12 不同撞击面坡度下参数m, η随坠落高度变化曲线
Figure 12. Parameter m, η under different impact angles of slopes
表 1 贵州省典型岩崩灾害统计
Table 1. Statistical table of typical rockfalls in Guizhou Province
灾害点名称 岩性 坡高/m 崩源坡度/(°) 坡中坡度/(°) 坡脚坡度/(°) 坠落高度/m 层面 优势节理J1 优势节理J2 节理贯通度 产状/(°) 黔南瓮安县白岩崩塌 灰岩 90 82 58 15 5 295∠11 192∠82 115∠72 0.3~0.6 思南县徐家大塝崩塌 灰岩 240 89 54 9 18 310∠15 150∠70 0.4~0.5 思南县椒子坪崩塌 灰岩 140 86 65 16 24 175∠12 215∠81 0.5~0.8 思南县新华村崩塌 灰岩 50 79 68 21 10 270∠41 80∠61 0.4~0.7 开阳县寨子组崩塌 白云岩 130 75 46 14 20 110∠40 285∠80 300∠65 0.7 三都县羊福民校崩塌 板岩 50 70 10 0 10 230∠84 250∠83 155∠85 0.4 三渡镇杨莫洞崩塌 灰岩 200 79 55 5 20 320∠22 275∠79 0.4~0.8 凤岗县新民街上崩塌 灰岩 80 71 28 12 15 300∠13 190∠70 0.4~0.7 赤水县集镇后山崩塌 砂岩 170 75 45 12 13 315∠3 65∠70 0.2~0.4 赤水市实验学校崩塌 泥岩 120 83 55 11 12 140∠10 230∠90 0.6 赤水市石鹅嘴崩塌 砂岩 130 71 51 13 11 170∠8 15∠85 0.3 学孔镇田坝崩塌 灰岩 130 73 35 14 9 300∠75 345∠70 0.2~0.5 安顺市小寨组崩塌 白云岩 80 87 45 9 15 135∠7 250∠86 0.3~0.4 安顺市元江煤矿崩塌 白云岩 140 76 60 10 24 220∠17 215∠75 已治理 盘州市白岩村崩塌 灰岩 40 82 35 5 9 225∠16 25∠75 0.3~0.5 兴义市村木扎崩塌 砂岩 350 88 31 9 50 151∠4 310∠87 0.4~0.6 水城县丫口组崩塌 灰岩 240 87 28 8 29 162∠18 247∠82 333∠89 0.5~0.8 六枝特区青龙山崩塌 灰岩 130 73 26 17 10 180∠17 47∠66 304∠60 0.4~0.7 大方县岩脚组崩塌 灰岩 180 85 55 23 23 296∠18 225∠78 0.5~0.8 大方县勤勇组崩塌 灰岩 360 75 65 13 35 343∠21 160∠70 0.4~0.6 大方县杓柏组崩塌 灰岩 380 85 62 12 20 63∠25 154∠72 0.5~0.6 纳雍县谢家岩崩塌 灰岩 210 83 53 17 15 20∠19 320∠79 216∠62 0.3~0.6 纳雍县营上组崩塌 灰岩 190 87 57 15 16 51∠18 216∠65 288∠50 0.5~0.6 纳雍县殷家岩崩塌 灰岩 260 72 55 11 28 51∠18 215∠76 115∠72 0.5~0.7 纳雍县拉落寨崩塌 灰岩 150 87 55 23 16 47∠17 175∠78 0.4~0.5 九仓镇大岭山崩塌 砂岩 350 70 45 19 20 284∠20 210∠78 0.3~0.6 纳雍县大偏坡崩塌 灰岩 280 71 42 16 23 112∠16 290∠80 0.3~0.5 
下载: 导出CSV
表 2 岩体动力破碎实验参数
Table 2. Parameters of dynamic fragmentation
实验编号 坡中撞击面坡度/(°) 岩性 坠落高度/m 坡脚撞击面坡度/(°) 节理倾角/(°) 节理连通率 1 30 灰岩 10 10 70 0.5 2 30 灰岩 20 10 70 0.5 3 30 灰岩 30 10 70 0.5 4 45 灰岩 10 10 70 0.5 5 45 灰岩 20 10 70 0.5 6 45 灰岩 30 10 70 0.5 7 60 灰岩 10 10 70 0.5 8 60 灰岩 20 10 70 0.5 9 60 灰岩 30 10 70 0.5
下载: 导出CSV
表 3 灰岩细观参数
Table 3. Microproperties of limestone
离散元参数 数值 离散元参数 数值 颗粒密度/(kg·m-3) 2 600 孔隙率/% 10 最小粒径/mm 0.5 平行黏结模量/GPa 25 粒径比(Rmax/Rmin) 1.66 平行黏结刚度比 2.5 颗粒接触模量/GPa 25 平行黏结法向刚度/MPa 20 颗粒刚度比 2.5 平行黏结切向刚度/MPa 15
下载: 导出CSV
表 4 光滑节理模型细观参数
Table 4. Microproperties of the smooth joint model
离散元参数 数值 离散元参数 数值 接触径向单元数 1 接触间距/mm 0.1 接触弹性模量/GPa 44 平行黏结模量/GPa 25 刚度比 1.1 摩擦系数 0.5 接触抗拉强度/MPa 15 接触黏结强度/MPa 12 内摩擦角/(°) 5
下载: 导出CSV
表 5 拟合参数值
Table 5. Fitting parameters
实验组 拟合结果 可决系数 m值 η值 1 Y=3.543 9X-22.981 1 0.973 2 3.543 9 655.04 2 Y=3.502 9X-22.561 1 0.978 7 3.502 9 626.84 3 Y=3.444 9X-22.084 2 0.984 5 3.444 9 608.31 4 Y=3.623 3X-23.547 5 0.965 4 3.623 3 664.42 5 Y=3.573 1X-23.054 6 0.987 7 3.573 1 634.25 6 Y=3.483 2X-22.394 2 0.981 4 3.483 2 619.68 7 Y=3.640 1X-23.699 9 0.980 8 3.640 1 672.36 8 Y=3.633 1X-23.517 8 0.983 8 3.633 1 647.55 9 Y=3.547 5X-22.856 7 0.982 3 3.547 5 628.31 式中: Pn为在第n点的累积质量概率；$ \sum\limits_{i = 1}^n {{V_i}} $为在第n点的累计体积；$ \sum\limits_{i = 1}^n {{V_i}} $为碎片总体积。
下载: 导出CSV
-
[1] 吕权儒, 曾斌, 孟小军, 等. 基于无人机倾斜摄影技术的崩塌隐患早期识别及影响区划分方法[J]. 地质科技通报, 2021, 40(6): 313-325. doi: 10.19509/j.cnki.dzkq.2021.0631Lü Q R, ZENG B, MENG X J, et al. Early identification and influence range division method of collapse hazards based on UAV oblique photography technology[J]. Bulletin of Geological Science and Technology, 2021, 40(6): 313-325. (in Chinese with English abstract) doi: 10.19509/j.cnki.dzkq.2021.0631 [2] 罗刚, 程谦恭, 沈位刚, 等. 高位高能岩崩研究现状与发展趋势[J]. 地球科学, 2022, 47(3): 913-934. https://www.cnki.com.cn/Article/CJFDTOTAL-DQKX202203013.htmLUO G, CHENG Q G, SHEN W G, et al. Research status and development trend of the high-altitude extremely-energetic rockfalls[J]. Earth Science, 2022, 47(3): 913-934. (in Chinese with English abstract) https://www.cnki.com.cn/Article/CJFDTOTAL-DQKX202203013.htm [3] 王豪, 黄健, 黄祥, 等. 一种利用Unity3D模拟崩塌三维运动全过程的方法[J]. 武汉大学学报(信息科学版), 2023, 48(12): 1990-1998. https://www.cnki.com.cn/Article/CJFDTOTAL-WHCH202312010.htmWANG H, HUANG J, HUANG X, et al. A Method of using unity 3D to simulate whole process of three-dimensional movement of rockfall[J]. Geomatics and Information Science of Wuhan University, 2023, 48(12): 1990-1998. (in Chinese with English abstract) https://www.cnki.com.cn/Article/CJFDTOTAL-WHCH202312010.htm [4] VOLKWEIN A, BRüGGER L, GEES F, et al. Repetitive rockfall trajectory testing[J]. Geosciences, 2018, 8(3): 88. doi: 10.3390/geosciences8030088 [5] 魏进兵, 何治良, 杨仲康. 考虑地震危险性的倾倒变形边坡风险定量分析[J]. 地质科技通报, 2022, 41(2): 71-78. doi: 10.19509/j.cnki.dzkq.2022.0018WEI J B, HE Z L, YANG Z K. Quantitative risk analysis of toppling slope considering seismic risk[J]. Bulletin of Geological Science and Technology, 2022, 41(2): 71-78. (in Chinese with English abstract) doi: 10.19509/j.cnki.dzkq.2022.0018 [6] 叶四桥, 陈洪凯, 唐红梅. 落石冲击力计算方法[J]. 中国铁道科学, 2010, 31(6): 56-62. https://www.cnki.com.cn/Article/CJFDTOTAL-ZGTK201006011.htmYE S Q, CHEN H K, TANG H M. The calculation method for the impact force of the rockfall[J]. China Railway Seience, 2010, 31(6): 56-62. (in Chinese with English abstract) https://www.cnki.com.cn/Article/CJFDTOTAL-ZGTK201006011.htm [7] 刘冀昆, 杨晓琳, 王成虎. S-SARⅡ技术的崩塌临灾应急监测原理及其应用[J]. 地质科技通报, 2023, 42(1): 42-51. doi: 10.19509/j.cnki.dzkq.tb20220495LIU J K, YANG X L, WANG C H. Principle and application of S-SARⅡ technology for collapse emergency monitoring[J]. Bulletin of Geological Science and Technology, 2023, 42(1): 42-51. (in Chinese with English abstract) doi: 10.19509/j.cnki.dzkq.tb20220495 [8] 唐红梅, 易朋莹. 危岩落石运动路径研究[J]. 重庆建筑大学学报, 2003, 25(1): 17-23. https://www.cnki.com.cn/Article/CJFDTOTAL-JIAN200301004.htmTANG H M, YI P Y. Research on dangerous rock movement route[J]. Journal of Chongqing Jianzhu University, 2003, 25(1): 17-23. (in Chinese with English abstract) https://www.cnki.com.cn/Article/CJFDTOTAL-JIAN200301004.htm [9] 何思明, 吴永, 沈均. 泥石流大块石冲击力的简化计算[J]. 自然灾害学报, 2009, 18(5): 51-56. https://www.cnki.com.cn/Article/CJFDTOTAL-ZRZH200905007.htmHE S M, WU Y, SHEN J. Simplified calculation of impact force of massive stone in debris flow[J]. Journal of Natural Disasters, 2009, 18(5): 51-56. (in Chinese with English abstract) https://www.cnki.com.cn/Article/CJFDTOTAL-ZRZH200905007.htm [10] DUFRESNE A, BÖSMEIER A, Prager C. Sedimentology of rock avalanche deposits: Case study and review[J]. Earth-Science Reviews, 2016, 163: 234-259. doi: 10.1016/j.earscirev.2016.10.002 [11] LOCAT P, COUTURE R, LEROUEIL S, et al. Fragmentation energy in rock avalanches[J]. Canadian Geotechnical Journal, 2006, 43(8): 830-851. doi: 10.1139/t06-045 [12] BOWMAN E T, TAKE W A, RAITK L, et al. Physical models of rock avalanche spreading behaviour with dynamic fragmentation[J]. Canadian Geotechnical Journal, 2012, 49(4): 460-471. doi: 10.1139/t2012-007 [13] SAROCCHI B D, NAHMAD-MOLINARI Y. Stick-slip motion and high speed ejecta in granular avalanches detected through a multi-sensors flume[J]. Engineering Geology, 2015, 195: 248-257. doi: 10.1016/j.enggeo.2015.06.019 [14] ZHAO T, CROSTA G B. On the dynamic fragmentation and lubrication of coseismic landslides[J]. Journal of Geophysical Research: Solid Earth, 2018, 123(11): 9914-9932. doi: 10.1029/2018JB016378 [15] ZHANG S, YIN Y, LI H, et al. Transport process and mechanism of the Hongshiyan rock avalanche triggered by the 2014 Ludian earthquake, China[J]. Landslides, 2022, 19(8): 1987-2004. doi: 10.1007/s10346-022-01878-8 [16] GIACOMINI A, BUZZI O, RENARD B. Experimental studies on fragmentation of rock falls on impact with rock surfaces[J]. International Journal of Rock Mechanics and Mining Sciences, 2009, 46(4): 708-715. doi: 10.1016/j.ijrmms.2008.09.007 [17] HAUG Ø T, ROSENAU M, LEEVER K, et al. On the energy budgets of fragmenting rockfalls and rockslides: Insights from experiments[J]. Journal of Geophysical Research: Earth Surface, 2016, 121(7): 1310-1327. doi: 10.1002/2014JF003406 [18] 吕庆, 周春锋, 于洋, 等. 滚石坡面碰撞破裂效应的试验研究[J]. 岩石力学与工程学报, 2017, 36(增刊1): 3359-3366. https://www.cnki.com.cn/Article/CJFDTOTAL-YSLX2017S1027.htmLü Q, ZHOU C F, YU Y, et al. Experimental study on fragmentation effects of rockfall impact upon slope[J]. Chinese Journal of Rock Mechanics and Engineering, 2017, 36(S1): 3359-3366. (in Chinese with English abstract) https://www.cnki.com.cn/Article/CJFDTOTAL-YSLX2017S1027.htm [19] LIN Q W, CHENG Q G, LI K, et al. Contributions of rock mass structure to the emplacement of fragmenting rockfalls and rockslides: Insights from laboratory experiments[J]. Journal of Geophysical Research: Solid Earth, 2020, 125(4): e2019JB019296. doi: 10.1029/2019JB019296 [20] 柴波, 陶阳阳, 杜娟, 等. 基于Hoek-Brown准则的节理岩体能量参数估算[J]. 地质科技通报, 2020, 39(1): 78-85. doi: 10.19509/j.cnki.dzkq.2020.0109CHAI B, TAO Y Y, DU J, et al. Energetics parameter estimation of jointed rock mass based on Hoek-Brown failure criterion[J]. Bulletin of Geological Science and Technology, 2020, 39(1): 78-85. (in Chinese with English abstract) doi: 10.19509/j.cnki.dzkq.2020.0109 [21] CAGNOLI B, PIERSANTI A. Grain size and flow volume effects on granular flow mobility in numerical simulations: 3-D discrete element modeling of flows of angular rock fragments[J]. Journal of Geophysical Research: Solid Earth, 2015, 120(4): 2350-2366. doi: 10.1002/2014JB011729 [22] WANG Y, TONON F. Discrete element modeling of rock fragmentation upon impact in rock fall analysis[J]. Rock Mechanics and Rock Engineering, 2011, 44(1): 23-35. doi: 10.1007/s00603-010-0110-9 [23] DE BLASIO F V, CROSTA G B. Fragmentation and boosting of rock falls and rock avalanches[J]. Geophysical Research Letters, 2016, 42(20): 8463-8470. [24] ZHAO T, CROSTA G B, DATTOLA G, et al. Dynamic fragmentation of jointed rock blocks during rockslide-avalanches: Insights from discrete element analyses[J]. Journal of Geophysical Research: Solid Earth, 2018, 123(4): 3250-3269. doi: 10.1002/2017JB015210 [25] XIA G Q, LIU C, XU C, et al. Dynamic analysis of the high-speed and long-runout landslide movement process based on the discrete element method: A case study of the Shuicheng landslide in Guizhou, China[J/OL]. Advances in Civil Engineering, 2021. doi: org/10.1155/2021/8854194 .[26] POTYONDY D O, CUNDALL P A. A bonded-particle model for rock[J]. International Journal of Rock Mechanics and Mining Sciences, 2004, 41(8): 1329-1364. doi: 10.1016/j.ijrmms.2004.09.011 [27] 冯兴波, 奚悦, 宋丹青, 等. 基于PFC~(2D)岩石颗粒破碎强度和能量的分形模型[J]. 工程地质学报, 2016, 24(4): 629-634. https://www.cnki.com.cn/Article/CJFDTOTAL-GCDZ201604023.htmFENG X B, XI Y, SONG D Q, et al. PFC2D based fractal model for tensile strength and breakage energy of rock particle crushing[J]. Journal of Engineering Geology, 2016, 24(4): 629-634. (in Chinese with English abstract) https://www.cnki.com.cn/Article/CJFDTOTAL-GCDZ201604023.htm [28] 孙新坡, 何思明, 于忆骅. 基于离散元法崩塌体动力破碎分析[J]. 浙江工业大学学报, 2015, 43(4): 464-467. https://www.cnki.com.cn/Article/CJFDTOTAL-ZJGD201504022.htmSUN X P, HE S M, YU Y H. Dynamic crush analysis of collapse bodies based on the discrete element method[J]. Journal of Zhejiang University of Technology, 2015, 43(4): 464-467. (in Chinese with English abstract) https://www.cnki.com.cn/Article/CJFDTOTAL-ZJGD201504022.htm [29] LIN Q W, CHENG Q G, XIE Y, et al. Simulation of the fragmentation and propagation of jointed rock masses in rockslides: DEM modeling and physical experimental verification[J]. Landslides, 2020, 18(24): 993-1009. [30] ZHANG S L, YIN Y P, HU X W, et al. Dynamics and emplacement mechanisms of the successive Baige landslides on the upper reaches of the Jinsha River China[J], Engineering Geology, 2020, 278: 105819. doi: 10.1016/j.enggeo.2020.105819 [31] 陈梓华. 基于离散元平直节理接触模型灰岩微裂纹扩展研究[D]. 广州: 华南理工大学, 2019.CHEN Z H. Discrete element simulation of limestone micro-fracturing processes with flat joint contact model[D]. Guangzhou: South China University of Technology, 2019. (in Chinese with English abstract) -
下载:
点击查看大图
计量
- 文章访问数: 37
- PDF下载量: 12
- 被引次数: 0
