Discuss on Plain Strain Model for Seismic Response of Underground Structure
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摘要: 采用平面应变模型对地下结构进行地震反应分析时,其核心问题是中柱的二维等效简化。常用的简化方法是将中柱的材料性质(如弹性模量和密度)进行折减。在此基础上,进一步引入空间约束影响系数和三维还原系数,提出新的中柱二维等效简化方法。针对不同简化方法,分别建立对应的地下结构地震反应分析平面应变模型,计算各模型的地震反应。通过与三维模型计算结果进行对比分析,研究不同简化方法的合理性。计算结果表明,本研究建议的方法可有效提高地下结构平面应变模型的计算精度。Abstract: The method to simplify inner column is a key point when plane strain model is picked to compute seismic response of underground structure. The commonly used simplification method for the inner columns is to reduce its values of material properties, such as Young’s Modulus and density. Based on common methods, the space constraint influence coefficient and the three-dimensional reduction coefficient were introduced in this paper furtherly, and a new plane strain model simplified method for the center column was proposed. According to three different simplified methods, three plane strain models for seismic response analysis of underground structures were established respectively, and the seismic response of each model was calculated. By comparing the calculation results with the three-dimensional model, the rationality of different simplification methods was discussed. The calculation results show that the method proposed in this paper can effectively improve the calculation accuracy of the plane strain model of underground structures.
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Key words:
- Underground structure /
- Seismic response /
- Plain strain model /
- Error of internal force
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表 1 场地土物理力学参数
Table 1. Physical parameters of site soil properties
土质 深度/m 密度/t·m−3 剪切波速/m·s−1 最大剪切模量/MPa 泊松比 人工填土 0~1.0 1.9 140 38.00 0.33 全新世砂土 1.0~5.1 1.9 140 38.00 0.32 全新世砂土 5.1~8.3 1.9 170 56.03 0.32 更新世黏土 8.3~11.4 1.9 190 69.99 0.40 更新世黏土 11.4~17.2 1.9 240 111.67 0.30 更新世砂土 17.2~22.2 2.0 330 222.24 0.26 表 2 三维模型的前7阶自振频率及横向(水平向)振型参与系数
Table 2. The first seven natural frequencies of three dimension model and modal participation factor of horizontal direction
参数 阶序 1 2 3 4 5 6 7 自振频率/Hz 2.66 2.72 2.73 2.76 2.77 2.79 2.89 参与系数/×104 1.00 0 0 0 0 0 0.48 表 3 二维模型的前7阶自振频率及横向(水平向)振型参与系数
Table 3. The first seven natural frequencies of two dimension model and modal participation factor of horizontal direction
参数 阶序 1 2 3 4 5 6 7 自振频率/Hz 2.64 2.79 2.87 3.24 3.45 3.95 4.20 参与系数/×104 0.23 0 0.10 0 0.25 0 0.02 表 4 中柱地震反应峰值
Table 4. Peak seismic response of the inner column
激励 考察点及反应量 三维模型 方法1 方法1a 方法2 方法2a 方法3 JY波 柱顶
(监测点P2)弯矩Mz/kN·m 253.61 84.12
(误差−66.83%)294.42
(误差16.09%)92.21
(误差−63.64%)322.72
(误差27.25%)263.87
(误差4.04%)剪力Fx/kN 60.40 13.71
(误差−77.29%)48.00
(误差−20.52%)22.54
(误差−62.68%)78.89
(误差30.63%)64.60
(误差6.97%)柱底
(监测点P3)弯矩Mz/kN·m 246.16 95.92
(误差−61.03%)335.74
(误差36.39%)88.93
(误差−63.87%)311.26
(误差26.44%)254.02
(误差3.19%)剪力Fx/kN 77.62 33.22
(误差−57.20%)116.28
(误差49.81%)27.61
(误差−64.43%)96.62
(误差24.48%)78.74
(误差1.44%)Kobe波 柱顶
(监测点P2)弯矩Mz/kN·m 52.13 16.82
(误差−67.72%)58.89
(误差12.97%)18.51
(误差−64.49%)64.78
(误差24.27%)52.90
(误差1.48%)剪力Fx/kN 12.57 2.90
(误差−76.94%)10.15
(误差−19.29%)4.55
(误差−63.80%)15.93
(误差26.71%)13.03
(误差3.62%)柱底
(监测点P3)弯矩Mz/kN·m 51.07 19.46
(误差−61.89%)68.12
(误差33.38%)18.02
(误差−64.72%)63.07
(误差23.50%)51.40
(误差0.65%)剪力Fx/kN 16.08 6.60
(误差−58.95%)23.10
(误差43.69%)5.61
(误差−65.09%)19.64
(误差22.17%)16.00
(误差−0.46%)WC波 柱顶
(监测点P2)弯矩Mz/kN·m 307.13 96.51
(误差−68.58%)337.79
(误差9.98%)105.99
(误差−65.49%)370.98
(误差20.79%)303.11
(误差−1.31%)剪力Fx/kN 73.78 16.79
(误差−77.24%)58.78
(误差−20.33%)26.11
(误差−64.62%)91.37
(误差23.84%)74.76
(误差1.34%)柱底
(监测点P3)弯矩Mz/kN·m 304.37 112.25
(误差−63.12%)392.87
(误差29.08%)103.49
(误差−66.00%)362.23
(误差19.01%)295.34
(误差−2.96%)剪力Fx/kN 96.71 38.91
(误差−59.77%)136.17
(误差40.80%)32.45
(误差−66.45%)113.56
(误差17.42%)92.43
(误差−4.43%)表 5 关键点地震反应峰值
Table 5. Peak seismic response of observation points
激励 考察点
及反应量三维模型 方法1 方法2 方法3 JY波 地表
(监测点P1)加速度a/m·s−2 4.22 4.49(误差6.32%) 4.48(误差6.21%) 4.49(误差6.32%) 位移u/mm 14.53 15.58(误差7.21%) 15.47(误差6.43%) 15.50(误差6.69%) 柱顶
(监测点P2)加速度a/m·s−2 4.53 4.99(误差10.22%) 4.96(误差9.49%) 4.98(误差9.81%) 位移u/mm 13.69 15.38(误差12.29%) 15.23(误差11.23%) 15.30(误差11.7%) 侧壁
(监测点P4)加速度a/m·s−2 1.64 1.62(误差−1.10%) 1.61(误差−2.13%) 1.61(误差−2.25%) 位移u/mm 3.41 3.48(误差1.85%) 3.46(误差1.28%) 3.45(误差1.02%) Kobe波 地表
(监测点P1)加速度a/m·s−2 0.86 0.87(误差1.20%) 0.87(误差1.01%) 0.87(误差1.00%) 位移u/mm 3.10 3.18(误差2.41%) 3.16(误差1.96%) 3.17(误差2.07%) 柱顶
(监测点P2)加速度a/m·s−2 0.80 0.85(误差6.06%) 0.84(误差5.51%) 0.84(误差5.82%) 位移u/mm 2.94 3.10(误差5.45%) 3.08(误差4.80%) 3.09(误差5.14%) 侧壁
(监测点P4)加速度a/m·s−2 0.30 0.29(误差−2.89%) 0.29(误差−3.72%) 0.29(误差−3.96%) 位移u/mm 0.78 0.77(误差−1.11%) 0.77(误差−1.50%) 0.77(误差−1.76%) WC波 地表
(监测点P1)加速度a/m·s−2 5.13 5.18(误差0.82%) 5.17(误差0.69%) 5.17(误差0.63%) 位移u/mm 18.75 18.62(误差−0.72%) 18.55(误差−1.10%) 18.56(误差−1.03%) 柱顶
(监测点P2)加速度a/m·s−2 4.80 4.87(误差1.54%) 4.86(误差1.27%) 4.87(误差1.44%) 位移u/mm 17.81 18.33(误差2.94%) 18.23(误差2.36%) 18.28(误差2.66%) 侧壁
(监测点P4)加速度a/m·s−2 1.39 1.40(误差1.12%) 1.39(误差0.62%) 1.39(误差0.47%) 位移u/mm 4.45 4.33(误差−2.66%) 4.32(误差−2.96%) 4.30(误差−3.26%) -
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