Mechanical Properties and Engineering Properties of Weathered Slate in Damen Area of Yunnan Province
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摘要: 掌握地基岩体的力学性质和工程特性,对评价岩土工程项目的安全性与稳定性至关重要。依托云南玉溪“十三五”规划某大型基建项目,对本区内主要地基土——中等风化炭质板岩和强风化炭质板岩的物理力学性质进行了深入研究。基于室内物理力学试验分别进行了中等风化板岩在天然和饱和状态下的单轴压缩试验,揭示了含水率增加对板岩单轴抗压强度的弱化规律,讨论了板岩在单轴应力作用下的典型破坏模式。基于室内颗粒分析试验对强风化板岩的级配特性进行描述,并基于现场原位剪切试验对其在不同含水率下的抗剪强度指标变化规律进行探讨。基于三种土工试验对中等风化板岩的化学组成以及强风化板岩的渗透性和承载力进行研究。研究成果可为本区域类似地质条件的工程建设提供参考。Abstract: A clear understanding of the geotechnical mechanical properties and engineering characteristics of foundation rock mass is very important to evaluate the safety and stability of engineering projects. Based on a large infrastructure project during the 13th Five-Year Plan period in Yuxi, Yunnan Province, the physical and mechanical properties of moderately weathered and strongly weathered carbonaceous slate in the main foundation soil layers in this area were deeply discussed. Firstly, uniaxial compression tests of moderately weathered slate under natural and saturated conditions were carried out based on indoor physical tests. The influence of water content on the uniaxial compressive strength of slate was revealed, and the typical failure mode of slate under uniaxial stress was discussed. Secondly, the gradation characteristics of strongly weathered slate were described based on the indoor particle analysis test. What is more, the variation of shear strength index of strongly weathered slate under different water content was discussed based on the in-situ shear test. Finally, the chemical composition of moderately weathered slate and the permeability and bearing capacity of strongly weathered slate were studied in detail based on three kinds of geotechnical tests. The results can provide guidance for the construction with similar geological conditions in this area.
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表 1 炭质板岩基本物理指标统计表
项目 比重 密度ρ/(g·cm−3) 吸水率
wa/%孔隙率
/%天然试样 饱和试样 频数 22 66 66 22 22 最大值 2.76 2.59 2.66 3.14 6.93 最小值 2.73 2.54 2.61 2.08 6.08 平均值 2.75 2.57 2.63 2.56 6.52 标准差 0.007 0.013 0.013 0.354 0.306 表 2 炭质板岩单轴抗压强度
MPa 编号 y-1 y-2 y-3 y-4 y-5 y-6 y-7 y-8 y-9 y-10 y-11 天然 10.62 9.31 8.15 8.36 8.81 9.97 8.99 8.82 8.10 10.16 10.07 饱和 5.82 5.68 4.58 5.27 5.27 4.67 5.56 5.49 5.41 5.60 5.13 软化系数 0.55 0.61 0.56 0.63 0.60 0.47 0.62 0.62 0.67 0.55 0.51 编号 y-12 y-13 y-14 y-15 y-16 y-17 y-18 y-19 y-20 y-21 y-22 天然 9.19 10.60 11.06 9.58 10.78 10.91 10.27 9.04 10.77 8.36 9.56 饱和 5.81 5.01 6.80 6.06 5.33 5.22 5.28 5.49 5.09 5.26 4.74 软化系数 0.63 0.47 0.61 0.63 0.49 0.48 0.51 0.61 0.47 0.63 0.50 表 3 强风化板岩颗粒分析结果汇总
统计
项目颗粒组成/% 碎块石
50.0~20.0
mm角砾石
20.0~2.00
mm粗砂
2.00~0.50
mm中砂
0.50~0.25
mm细砂
0.25~0.075
mm粉砂
0.075~0.05
mm粉粒粗
0.05~0.01
mm粉粒细
0.01~0.005
mm黏粒
<0.005
mm样本1 33.1 33.1 5.8 0.5 0.4 27.1 样本2 28.9 37.8 6.5 0.9 0.3 25.6 样本3 40.1 23.2 4.5 0.9 0.4 30.9 样本4 45.8 17.7 5.2 1.3 0.5 29.5 样本5 31.0 35.8 6.7 1.1 0.4 25.0 样本6 16.0 45.5 8.5 1.7 0.6 27.7 样本7 31.4 26.4 2.7 0.7 0.6 38.2 样本8 35.8 32.0 5.9 0.5 0.4 25.4 平均 32.8 31.4 5.7 1.0 0.5 28.7 表 4 强风化板岩剪切强度及抗剪强度指标汇总
试验编号 试验深度/m 含水情况 剪切强度/kPa 黏聚力c/kPa 内摩擦角φ/(°) 法向应力
75 kPa法向应力
155 kPa法向应力
235 kPa法向应力
315 kPa法向应力
395 kPaDJ-1-A 0.5 天然 75 105 152 174 215 41.68 23.57 DJ-1-B 0.7 浸水 61 98 142 161 193 34.94 22.23 DJ-2-A 0.5 天然 77 112 144 176 211 46.48 22.54 DJ-2-B 0.7 浸水 65 103 138 162 183 43.54 20.24 DJ-3-A 0.5 天然 84 118 147 195 217 51.44 23.21 DJ-3-B 0.7 浸水 79 106 131 162 202 47.29 20.68 表 5 炭质板岩光谱半定量检测数据统计表(ω(B)/(10−2))
元素名称 样本编号 元素名称 样本编号 元素名称 样本编号 1 2 3 1 2 3 1 2 3 钡Ba 0.026 0.025 0.025 钇Y 0.002 <0.002 0.002 钴Co 0.003 0.002 0.002 铍Be <0.001 <0.001 <0.001 锂Li <0.003 <0.003 <0.003 钾K >2.0 >2.0 >2.0 砷As <0.020 <0.020 <0.020 铬Cr 0.006 0.006 0.005 锶Sr <0.030 <0.030 <0.030 锑Sb <0.003 <0.003 <0.003 铁Fe 9 8 8.5 银Ag <0.0001 <0.0001 <0.0001 锰Mn 0.05 0.045 0.045 锗Ge <0.001 <0.001 <0.001 镍Ni <0.001 <0.001 <0.001 镁Mg >1.0 >1.0 >1.0 铋Bi <0.001 <0.001 <0.001 锆Zr 0.01 <0.010 0.012 铅Pb 0.006 0.006 0.007 铝Al >5.0 >5.0 >5.0 铜Cu 0.006 0.008 0.007 锡Sn 0.001 0.001 0.001 铌Nb <0.002 <0.002 <0.002 钠Na <0.50 <0.50 <0.50 硅Si >25.0 >25.0 >25.0 钼Mo <0.001 <0.001 <0.001 钪Sc <0.001 <0.001 <0.001 镓Ga <0.002 <0.002 <0.002 钙Ca <0.50 <0.50 <0.50 镱Yb 0.015 0.015 0.015 钨W <0.003 <0.003 <0.003 镧La <0.005 <0.005 <0.005 锌Zn 0.25 0.24 0.25 钒V 0.006 0.007 0.005 镉Cd <0.002 <0.002 <0.002 表 6 现场注水试验结果统计表
时间间隔t/s 渗流流量Q/(cm3·s−1) 渗透系数kt/(10−4 cm·s−1) t0–t1 2165 9.19 t1–t2 2052 8.71 t2–t3 2102 8.92 t3–t4 2064 8.76 t4–t5 2128 9.03 t5–t6 2114 8.97 表 7 板岩重型(N120)动力触探试验结果统计表
实验
编号修正后锤击数
N120/击修正后锤击数
N120平均值/击CT-1 8.5 9.8 CT-2 9.1 CT-3 11.4 CT-4 7.7 CT-5 10.9 CT-6 9.8 -
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