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摘要: 运用MARC软件, 通过研编用户子程序模拟车辆的移动荷载, 应用迭代接触算法Contact和单元生死技术模拟搭板与填土之间接触和脱空的不同受力状态, 并基于均匀沉降和不均匀沉降两种地基模式, 考虑搭板受力和变形的耦合, 分析了搭板的受力特性和适应性。当脱空长度在1.08 m范围内时, 板底弯拉应力值与完全弹性支承时相等, 但随着脱空长度的继续增大而显著增大, 完全脱空时板底弯拉应力与简支板相等, 板底最大弯拉应力的荷载作用位置在桥台与1/2板长之间。搭板对地基沉降的适应性表现为: 长度6 m的搭板适用于处理地基沉降在3 cm以内的桥头路段; 8 m长度的搭板适用于处理地基沉降在4 cm以内的桥头路段, 而10 m搭板适用于处理地基沉降在5 cm以内的桥头路段。Abstract: With MARC program, subroutine program of simulating vehicle moving load, contact iterative computing method and element life-death technique, the different mechanics states of contact and separation between slab and filling were simulated, on the basis of different foundation settlement modes, the coupling action of slab internal force and deformation was considered, the mechanics property and adaptability of slab were researched.The result shows that the flexural-tensile stress at the bottom of slab is not influenced when the length of slab separation section is less than 1.08 m, observably increases with the increase of the length, and the loading position of the maximum flexural-tensile stress at the bottom of slab is between the abutment and half of length of slab; the slab of length 6 m is suitable for treating the foundation that the settlement value is less than 3 cm, 8 m for 4 cm, 10 m for 5 cm.
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Key words:
- bridge engineering /
- approach slab /
- MARC program /
- mechanics property /
- adaptability
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表 1 计算参数
Table 1. Computation Parameters
材料 参数 弹性模量/MPa 泊松比 密度/ (kg·m-3) 路堤填土 50.0 0.35 2 000 搭板 2.8×104 0.15 2 400 
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表 2 搭板弯曲应力
Table 2. Flexural stress of slab
板长为6 m 脱空区长度/m 0 1.08 2.16 3.24 4.32 完全脱空 简支板 σmax/MPa 1.620 1.620 1.850 2.330 3.000 4.080 4.125 σmin/MPa -1.836 -1.836 -2.067 -2.522 -3.145 -4.196 -4.228 荷载距桥台距离/m 1.62~1.89 1.62~1.89 1.62~1.89 1.89~2.16 2.16~2.43 3.00 2.16~2.43 板长为8 m 脱空区长度/m 0 1.08 2.16 3.24 4.32 5.13 6.21 完全脱空 简支板 σmax/MPa 1.210 1.220 1.530 2.100 2.750 3.320 4.360 6.130 6.137 σmin/MPa -1.301 -1.306 -1.749 -2.312 -2.913 -3.448 -4.460 -6.207 -6.214 荷载距桥台距离/m 1.62~1.89 1.62~1.89 1.35~1.62 1.62~1.89 2.16~2.43 3.24~3.51 2.70~2.97 4.00 4.00 板长为10 m 脱空区长度/m 0 1.08 1.89 3.24 4.05 5.13 6.48 8.10 完全脱空 简支板 σmax/MPa 1.210 1.160 1.390 2.010 2.370 2.930 3.740 5.220 6.990 6.987 σmin/MPa -1.254 -1.212 -1.441 -2.074 -2.913 -2.980 -3.787 -5.267 -7.031 -7.030 荷载距桥台距离/m 1.62~1.89 1.62~1.89 1.62~1.89 1.62~1.89 2.16~2.43 2.43~2. 70 3.24~3.51 4.05~4.32 5.00 5.00
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表 3 纵坡变化率
Table 3. Longitudinal gradient change ratio
板长为6 m 地基沉降/cm 0 2 4 6 8 10 纵坡变化率/% 0.100 0.462 0.807 1.151 1.495 1.830 板长为8 m 地基沉降/cm 0 2 4 6 8 10 纵坡变化率/% 0.122 0.350 0.606 0.860 1.110 1.360 板长为10 m 地基沉降/cm 0 2 4 6 8 10 纵坡变化率/% 0.076 0.282 0.490 0.694 0.895 1.095
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