Mechanical Properties of Wet Concrete Inside Double-Block Ballastless Tracks in Rainy Areas
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摘要:
长期处于水环境中的双块式无砟轨道内部存在不均匀的湿度场，而湿度会对轨道结构的力学性能产生一定的影响. 为研究水环境中双块式无砟轨道内部不同湿度状态下混凝土宏观力学性能，结合水环境中双块式无砟轨道的湿度分布情况，建立了混凝土基质纳观组分（C-S-H）分子动力学模型，对混凝土基质展开多尺度计算，并进行两级均匀化分析. 结果表明：水环境中的双块式无砟轨道结构表层湿度的梯级分化明显，轨道内部的湿度差最高可达38.41%；混凝土的弹性模量和泊松比随饱和度的增加而增大；混凝土饱和度由0增加到100.00%时，支承层、道床板及轨枕混凝土弹性模量的增幅分别可达35.0%、19.5%、16.2%.
Abstract:An uneven humidity field forms inside double-block ballastless tracks long located in the water environment, and humidity will affect the mechanical properties of track structures. In order to study the macroscopic mechanical properties of concrete under different humidity conditions inside the double-block ballastless tracks in the water environment, combined with the humidity distribution of the double-block ballastless track in the water environment, the molecular dynamics of the nano-component (C-S-H) of the concrete matrix is established. Multi-scale calculation of concrete matrix and two-level homogenization analysis are conducted. The results show that the surface humidity of double-block ballastless tracks in the water environment show distinct gradient differentiation, and the maximum humidity difference inside the tracks can reach up to 38.41%; the elastic modulus and Poisson’s ratio of concrete increase with saturation; when concrete saturation is increased from 0 to 100%, the increases of the elastic modulus of the bearing layer, the track bed slab and the sleeper concrete attain 35.0%, 19.5% and 16.2%, respectively.
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Key words:
- double-block ballastless track /
- water environment /
- humidity filed /
- wet concrete /
- material property
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图 1 双块式无砟轨道湿度场的二维有限元模型
Figure 1. Two-dimensional finite element model ofhumidity field in double-block ballastless tracks
图 2 水环境中湿度场分布
Figure 2. Distribution of humidity field in sleeper area in water environment
表 1 双块式无砟轨道构件尺寸及材料参数
Table 1. Dimensions and material parameters of double-block ballastless track components
构件 参数 取值 C60 混凝土轨枕块 水灰比 0.32 长、宽、高/mm 800、300、150 密度（kg·m−3） 2500 C40 混凝土道床板 水灰比 0.38 宽、高/mm 2800、260 密度/（kg·m−3） 2450 C20 混凝土支承层 水灰比 0.66 宽、高/mm 3400、300 密度/（kg·m−3） 2300 
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表 2 水环境中双块式无砟轨道湿度区间及其代表值
Table 2. Humidity interval and representative values of double-block ballastless tracks in water environment
% 湿度
区间轨枕区域 枕间区域 湿度 代表湿度 湿度 代表
湿度1 [61.59，65.85] 64.00 [65.80，69.60] 68.00 2 (65.85，70.12] 68.00 (69.60，73.40] 72.00 3 (70.12，74.39] 72.00 (73.40，77.20] 75.00 4 (74.39，78.66] 77.00 (77.20，81.00] 79.00 5 (78.66，82.93] 81.00 (81.00，84.80] 83.00 6 (82.93，87.20] 85.00 (84.80，88.60] 87.00 7 (87.20，91.46] 89.00 (88.60，92.40] 91.00 8 (91.46，95.73] 94.00 (92.40，96.20] 94.00 9 (95.73，100.00] 98.00 (96.20，100.00] 98.00
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表 3 各层级两相复合材料的具体组分
Table 3. Specific components of two-phase composite at each level
研究
对象层级 两相
复合材料夹杂相 基质相 C-S-H
凝胶Ⅰ HD/LD
C-S-H凝胶孔及
内部水C-S-H 胶束 C-S-H 凝胶 LD/HD
C-S-HHD/LD
C-S-H硬化水泥浆体骨架 Ⅱ 水化产物 CH 晶体 C-S-H 凝胶 硬化水泥浆体骨架 未水化
水泥颗粒水化产物 水泥砂浆骨架 Ⅲ 水泥砂浆骨架 细骨料 硬化水泥
浆体骨架混凝土基质 Ⅳ 混凝土基质 粗骨料 水泥砂浆骨架
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表 4 各层级夹杂相的力学参数
Table 4. Mechanical parameters of inclusion at each level
层级 夹杂相 弹性模量
E/GPa体积
模量/GPa剪切
模量/GPa泊松比
υⅠ 饱和凝胶孔 2.20 0 非饱和
凝胶孔0 0 Ⅱ CH晶体 40.00 160.00 未水化
水泥颗粒135.00 0.27 Ⅲ 细骨料 34.60 0.21 Ⅳ 粗骨料 54.00 0.20
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表 6 混凝土基质等效力学参数计算结果
Table 6. Calculation results of equivalent mechanical parameters for concrete matrix
混凝土强度等级 湿度/% 等效体积模量/GPa 等效剪切模量/GPa 等效弹性模量/GPa υ C20 64.00 ~ 98.00 24.59 16.12 39.69 0.23 C40 64.00 27.00 17.01 42.17 0.24 68.00 27.09 17.00 42.18 0.24 72.00 ~ 98.00 27.20 16.94 42.09 0.24 C60 64.00 27.47 17.02 42.31 0.24 68.00 27.53 17.03 42.37 0.24 72.00 27.67 17.03 42.39 0.24 75.00 ~ 98.00 27.76 16.99 42.33 0.25
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表 7 轨枕区域不同湿度状态混凝土的有效力学参数
Table 7. Effective mechanical parameters of concrete in different humidity states in track-sleeper areas
湿度区间 代表湿度/% C20 混凝土（支承层） C40 混凝土（道床板） C60 混凝土（轨枕） S/% E/GPa υ S/% E/GPa υ S/% E/GPa υ 1 64.00 0.05 24.71 0.22 0 29.43 0.22 0 30.91 0.23 2 68.00 0.11 24.71 0.22 0 29.43 0.23 0 30.91 0.23 3 72.00 0.21 24.71 0.22 0.30 29.44 0.23 0 30.91 0.23 4 77.00 0.51 26.72 0.22 2.54 29.66 0.23 10.67 31.60 0.23 5 81.00 1.16 28.74 0.23 6.88 29.94 0.23 36.06 32.56 0.23 6 85.00 3.32 28.93 0.23 17.83 30.85 0.23 70.36 33.38 0.23 7 89.00 13.78 29.91 0.23 45.16 32.16 0.23 81.53 34.34 0.23 8 94.00 79.17 31.43 0.24 79.84 34.03 0.24 81.60 35.89 0.23 9 98.00 100.00 33.35 0.25 100.00 35.17 0.24 100.00 35.93 0.23
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表 8 枕间区域不同湿度状态混凝土的有效力学参数
Table 8. Effective mechanical parameters of concrete in different humidity states in areas between sleepers
湿度区间 代表湿度/% C20 混凝土（支承层） C40 混凝土（道床板） S/% E/GPa υ S/% E/GPa υ 1 68.00 0.11 24.71 0.22 0 29.43 0.22 2 72.00 0.21 24.71 0.22 0.30 29.44 0.23 3 75.00 0.35 24.71 0.22 1.39 29.55 0.23 4 79.00 0.75 26.72 0.22 4.25 29.77 0.23 5 83.00 1.89 28.74 0.23 11.06 30.11 0.23 6 87.00 6.41 29.36 0.23 28.73 30.91 0.23 7 91.00 31.88 30.91 0.23 64.92 32.84 0.23 8 94.00 79.17 31.43 0.24 79.84 34.03 0.24 9 98.00 100.00 33.35 0.25 100.00 35.17 0.24
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