Analysis on the interception effect of neosinocalamus affinis on small falling rocks
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摘要:
落石灾害是我国西南地区常见的一种小型崩塌。落石对下方公路、桥梁、铁路等基础设施安全造成严重威胁。因此,如何对落石进行有效的拦截就显得尤为重要。常见的拦截设施,如拦石沟,拦石网,挡墙等,在布设时极易受地形、施工等因素的限制,有时难以大面积地布置,导致拦挡效果大为减弱。我国的西南地区生长着大量慈竹,慈竹具有生长快、繁殖能力强、抗弯折等特点,对落石具有很好的拦截效果。文章通过模型试验与数值模拟相结合的方法,对慈竹的抗冲击能力进行了研究并提出了慈竹拦截小型落石的方案。结果如下:(1)慈竹破坏所需能量随着直径和壁厚的变大而上升,随着年龄、长重比和长径比的增大而降低;(2) 一丛慈竹在抗冲击过程中最少能消耗3975.55 J能量,最多能消耗10890.88 J能量;(3)结合CRockfall软件进行慈竹落石拦截效应计算,结果显示拦截边坡高度43 m、直径0.5 m的危岩,需栽种2列3行6丛慈竹。
Abstract:Dangerous rock disaster is prevalent geological hazard in southwest China. Under the influence of gravity, dangerous rock masses can easily trigger rockfalls, posing a significant threat to infrastructure such as roads, bridges, and railways. Therefore, it is crucial to effectively intercept rockfalls. Common interception facilities, including stone-blocking trenches, stone-blocking nets, and retaining walls, are often constrained by terrain and construction limitations, making it difficult to implement them on a large scale and resulting in reduced interception effectiveness. The southwestern region of China is rich in Cizhu bamboo, which exhibits rapid growth, strong reproductive capabilities, and resistance to bending, rendering it highly effective in intercepting falling rocks. This study employs a combination of model testing and numerical simulation to investigate the impact resistance of Cizhu bamboo and proposes a strategy for using Cizhu bamboo to intercept small-scale rockfalls. The research findings are as follows: (1) The energy requirements of Cizhu bamboo increase with diameter and wall thickness, while decreasing with age, length-to-weight ratio, and aspect ratio. (2) A cluster of Cizhu bamboo can consume a minimum of 3975.55 J and a maximum of 10890.88 J of energy during impact resistance. (3) Utilizing the CRockfall software, the interception effect of Cizhu bamboo on rockfalls is calculated, indicating that a slope with a height of 43 m and a dangerous rock of 0.5 m in diameter requires the planting of 2 rows, 3 lines, and 6 clusters of Cizhu bamboo.
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表 1 慈竹直径 、壁厚试验结果
Table 1. Experimental results of diameter and wall thickness of bamboo
试验参数 数值 最大值/J 最小值/J 平均值/J 样本/根 平均值/J 标准差 变异系数 修正系数 标准值
/J直径/mm 新生竹 35~40 275.34 197.90 251.68 4 251.68 36.76 0.1461 0.8329 209.61 51~45 283.95 223.71 253.11 12 253.11 20.90 0.0826 0.9567 242.15 46~50 309.76 223.71 255.44 16 255.44 22.16 0.0867 0.9615 245.6 51~55 344.18 240.92 268.06 13 268.06 27.85 0.1039 0.948 0 254.13 老竹 39~40 240.92 206.51 223.71 3 223.71 17.21 0.0769 0.8844 197.84 41~45 258.13 215.11 240.92 11 240.92 15.39 0.0639 0.9647 232.42 46~51 275.34 223.71 241.54 15 245.22 18.32 0.0747 0.9656 236.78 壁厚/mm 新生竹 4 275.34 197.90 250.60 8 250.60 26.22 0.1046 0.9293 232.89 5 283.95 223.71 246.45 14 246.45 19.86 0.0806 0.9614 236.94 6 283.95 240.92 260.43 15 260.43 13.98 0.0537 0.9753 253.99 7~9 344.18 240.92 281.79 8 281.79 33.09 0.1174 0.9207 259.44 老竹 4 249.53 206.51 240.92 3 238.05 13.15 0.0552 0.917 0 218.29 5 258.13 223.71 240.92 15 240.35 18.24 0.0759 0.965 0 231.94 6~7 275.34 240.92 258.13 12 243.79 19.18 0.0787 0.9587 233.73 注:竹龄小于等于1 a的为新生竹,竹龄2~3 a的为老竹。 表 2 长重比、年龄和长径比试验结果
Table 2. Experimental results of length-to-weight ratio, age and length-to-diameter ratio
试验参数 数值 最大值/J 最小值/J 平均值/J 样本/根 平均值
/J标准差 变异系数 修正系数 标准值
/J年龄/a 新生竹 1 344.18 197.90 258.13 44 258.13 24.95 0.0967 0.9752 251.73 老竹 2~3 275.34 206.51 241.50 30 241.50 17.78 0.0736 0.9763 235.77 长重比
/(m·kg−1)新生竹 0.9~1.3 344.18 240.92 269.60 15 269.60 28.66 0.1063 0.951 0 256.40 1.4~1.8 275.34 223.71 254.16 14 254.44 18.40 0.0723 0.9653 245.63 1.9~2.7 283.95 197.90 250.60 16 250.60 23.70 0.0946 0.958 0 240.07 老竹 1.2~1.3 275.34 223.71 245.70 9 245.70 22.81 0.0928 0.9419 231.43 1.5~1.6 258.13 215.11 241.78 10 241.78 14.88 0.0615 0.964 0 233.07 1.7~2.2 258.13 206.51 237.79 11 237.79 16.45 0.0692 0.9618 228.71 长径比 新生竹 65~70 292.55 240.92 259.85 10 259.85 18.50 0.0712 0.9583 249.02 71~76 344.18 249.53 278.21 9 278.21 30.42 0.1094 0.9316 259.17 77~85 283.95 223.71 253.21 14 253.21 18.71 0.0739 0.9646 244.25 86~103 275.34 197.90 247.37 12 247.37 25.19 0.1018 0.9466 234.17 老竹 65~70 275.34 223.71 251.44 9 251.44 19.61 0.078 0 0.9512 239.17 71~79 258.13 223.71 237.79 11 237.79 13.48 0.0567 0.9687 230.34 81~97 258.13 206.51 236.62 10 236.62 18.25 0.0771 0.9548 225.93 注:竹龄小于等于1 a的为新生竹,竹龄2~3 a的为老竹 表 3 冲击位置和径厚比试验结果
Table 3. Experimental results of impact position and diameter-to-thickness ratio
试验参数 数值 最大值/J 最小值/J 平均值/J 样本/根 平均值
/J标准差 变异系数 修正系数 标准值
/J冲击位置/m 新生竹 0.5~0.9 344.18 223.71 260.82 16 260.82 26.79 0.1027 0.9544 248.92 1.0~1.5 275.34 197.90 251.51 13 251.51 23.6 0.0939 0.953 0 239.70 1.7~2.6 309.76 223.71 260.82 16 260.82 24.69 0.0946 0.958 0 249.85 老竹 0.6~0.9 275.34 215.11 246.66 9 246.66 20.63 0.0837 0.9477 233.75 1.0~1.5 266.74 223.71 243.79 9 243.79 15.51 0.0636 0.9602 234.08 1.6~1.9 258.13 206.51 235.90 12 235.90 17.00 0.072 0 0.9622 226.99 径厚比 新生竹 6~7 309.76 240.92 268.89 8 268.89 20.44 0.076 0 0.9486 255.08 8 344.18 233.71 266.74 13 266.74 31.42 0.1178 0.9411 251.02 9 283.95 197.90 250.24 12 250.24 23.91 0.0955 0.9499 237.71 10~13 275.34 223.71 249.53 12 249.53 15.99 0.0641 0.9664 241.14 老竹 7 275.34 223.71 246.05 5 246.08 18.85 0.0766 0.9273 228.19 8 275.34 206.51 234.66 11 234.66 20.03 0.0853 0.9529 223.60 9 266.74 223.71 245.84 7 245.84 15.60 0.0634 0.9531 234.30 10~12 258.13 223.71 244.61 7 244.61 15.60 0.0638 0.9528 233.07 注:竹龄小于等于1 a的为新生竹,竹龄2~3 a的为老竹 表 4 不同直径不同厚度模拟结果
Table 4. Simulation results for different diameters and thicknesses
直径/cm 厚度/m 最大值/J 最小值/J 位移/cm 总能量/J 内能/J 动能/J 5 0.003 240.86 110.670 −14.51 145.53 143.60 1.9327 0.004 247.79 10.194 −14.58 187.17 180.43 16.878 0.005 269.17 52.546 0.12 224.54 211.99 14.560 0.006 338.63 37.174 12.50 314.85 301.52 13.328 6 0.003 276.50 102.050 −12.40 86.27 53.23 33.035 0.004 276.50 30.800 −0.18 158.52 116.95 41.572 0.005 314.60 63.086 0.11 97.08 73.519 24.421 0.006 372.06 18.030 0.19 155.13 116.19 38.930 7 0.003 299.07 77.015 −24.83 107.97 75.00 32.939 0.004 306.78 44.891 −46.61 103.42 85.59 17.833 0.005 330.53 37.910 0.10 142.89 126.14 32.950 0.006 414.25 0.830 −0.11 177.09 147.70 29.392 表 5 物理模型试验与数值模拟对比
Table 5. Comparison between physical model experiment and numerical simulation
厚度/m 慈竹破坏所需能量/J 物理模型试验 数值模拟 0.003 153.87 145.53 0.004 198.55 187.17 0.005 234.44 224.54 0.006 328.62 314.85 表 6 一丛慈竹消耗能量
Table 6. The energy consumption of a bamboo cluster
根/丛 <4:4~6:6~8cm <4 4~6 6~8 J/丛 26 21.38:58.15:20.17 6 15 5 5941.27 18 31.14:61.83:6.92 6 11 1 3975.55 30 72.18:26.99:0.83 22 8 0 5899.98 表 7 落石坡段信息
Table 7. Falling rock section information
序号 水平投影长度/m 竖向投影长度/m 坡段长/m 坡角/(°) 1 9.8 0 9.800 −0 2 1.6 8.2 8.355 78.959 3 2.1 7.6 7.885 74.554 4 3.9 11.0 11.671 70.478 5 4.0 8.1 9.034 63.719 6 14.1 6.6 15.568 25.084 7 25.8 1.7 25.856 3.770 8 25.7 0.3 25.702 −0.669 表 8 数据采集器结果
Table 8. Data collector results
参数 最大值 95%保证率值 平均值 速度/(m·s−1) 10.405 8.848 4.177 冲击能量/kJ 7.794 1.849 0.468 弹跳高度/m 0.766 0.636 0.244 采集点位置/m 27.043 横向威胁范围/m 3.207 -
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