Analysis of the local site effect in Longtoushan town
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摘要: 依据龙头山集镇6个典型场地上的钻探资料及土体的动力非线性特性试验数据,分别建立了相应场地的地震反应分析模型。以幅值折半的龙头山镇强震动台站(053LLT)东西向主震加速度记录作为入射地震动,采用一维土层地震反应分析等效线性化方法计算了场地地震反应,讨论了近地表覆盖土层结构对地震动加速度峰值及反应谱的影响,并对场地效应与震害的关系进行了分析。Abstract: Based on the drilling data of six typical sites in Longtoushan town and the test data of dynamic nonlinear characteristics of soil, the seismic response analysis models of the corresponding sites were established respectively. Under the action of ground motion acceleration in east-west direction obtained by Longtoushan town strong observation station (053LLT) during Ludian earthquake with half-amplitude, the equivalent linearization method of one-dimensional soil layer seismic response analysis was used to calculate the seismic response of each site and the effect of near-surface overburden soil layer on peak acceleration. Response spectrum of ground motion was also discussed, and the relationship between site effect and earthquake damage was analyzed.
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表 1 6个钻孔的分析模型及土体力学特性参数值
Table 1. Analysis model and parameters of soil mechanical properties of six boreholes
钻孔 序号 岩土层名 层底深度/m 层厚/m 剪切波速/(m•s−1) 岩土密度/(g•cm−3) 土类号 DZK1 1 杂填土 3.2 3.2 185.0 1.87 24 2 圆砾 11.8 8.6 281.0 2.25 1 3 圆砾 19.1 7.3 327.0 2.25 2 4 砾砂 23.0 3.9 310.0 2.15 3 5 砾砂 26.0 3.0 310.0 2.15 4 6 计算基底 758.0 2.50 26 DZK2 1 素填土 1.2 1.2 201.0 1.72 24 2 圆砾 4.5 3.3 277.0 2.25 12 3 粉土 5.1 0.6 270.0 1.96 5 4 圆砾 7.0 1.9 328.0 2.25 1 5 漂石 7.8 0.8 542.0 2.45 26 6 全-强风化石英砂 15.6 7.8 453.0 2.23 6 7 断层角砾岩 18.0 2.4 521.0 2.45 26 8 全-强风化石英砂 59.1 41.1 496.0 2.23 6 9 计算基底 586.0 2.50 26 DZK3 1 杂填土 1.2 1.2 190.0 1.87 24 2 圆砾 9.9 8.7 379.0 2.25 1 3 含砾粉质粘土 12.1 2.2 332.0 1.94 7 4 角砾 13.5 1.4 445.0 2.10 25 5 碎石 16.0 2.5 472.0 2.10 25 6 砾砂 21.2 5.2 434.0 2.15 3 7 含砾粉质粘土 24.3 3.1 431.0 1.99 9 8 计算基底 539.0 2.50 26 DZK4 1 杂填土 3.2 3.2 211.0 1.87 24 2 卵石 4.7 1.5 432.0 2.10 25 3 圆砾 9.8 5.1 417.0 2.25 1 4 含砾粉质粘土 12.5 2.7 375.0 1.94 7 5 粉土 13.2 0.7 379.0 1.96 5 6 含砾粉质粘土 18.0 4.8 385.0 1.97 8 7 含砾粉质粘土 24.0 6.0 385.0 1.99 9 8 含砾粉质粘土 30.1 6.1 385.0 2.00 10 9 全-强风化白云质灰岩 59.0 28.9 462.0 2.20 11 10 计算基底 510.0 2.50 26 DZK5 1 素填土 1.0 1.0 281.0 1.72 24 2 圆砾 6.7 5.7 391.0 2.25 12 3 卵石 7.7 1.0 440.0 2.10 25 4 圆砾 9.5 1.8 419.0 2.25 13 5 圆砾 11.5 2.0 419.0 2.25 14 6 圆砾 15.0 3.5 419.0 2.25 15 7 圆砾 21.8 6.8 419.0 2.25 16 8 全-强风化白云质灰岩 22.5 0.7 545.0 2.20 11 9 断层泥 23.1 0.6 392.0 1.86 17 10 中风化白云质灰岩 27.5 4.4 759.0 2.50 26 11 断层泥 28.3 0.8 392.0 1.86 17 12 计算基底 759.0 2.50 26 DZK6 1 素填土 1.0 1.0 165.0 1.72 24 2 粉质粘土 4.4 3.4 217.0 1.92 18 3 粘土 6.5 2.1 213.0 1.86 19 4 含砾粉质粘土 9.2 2.7 234.0 1.86 20 5 砾砂 10.8 1.6 274.0 2.15 3 6 粘土 11.6 0.8 321.0 1.86 19 7 砾砂 13.7 2.1 259.0 2.15 3 8 粉质粘土 15.5 1.8 360.0 2.03 21 9 粉质粘土 18.7 3.2 360.0 1.85 22 10 全-强风化白云质灰岩 26.5 7.8 703.0 2.20 23 11 计算基底 804.0 2.50 26 表 2 不同土类的动力非线性特性参数值
Table 2. Dynamic nonlinear characteristic parameter values of different soil types
土类号 岩土名称 剪应变(γ)/10−4 0.05 0.1 0.5 1 5 10 50 100 模量比
(G/Gmax)阻尼比
(λ)模量比
(G/Gmax)阻尼比
(λ)模量比
(G/Gmax)阻尼比
(λ)模量比
(G/Gmax)阻尼比
(λ)模量比
(G/Gmax)阻尼比
(λ)模量比
(G/Gmax)阻尼比
(λ)模量比
(G/Gmax)阻尼比
(λ)模量比
(G/Gmax)阻尼比
(λ)1 圆砾 0.9976 0.0060 0.9952 0.0093 0.9765 0.0252 0.9541 0.0382 0.8061 0.0942 0.6752 0.1301 0.2937 0.2116 0.1721 0.2337 2 圆砾 0.9954 0.0037 0.9909 0.0063 0.9560 0.0212 0.9157 0.0351 0.6847 0.0976 0.5206 0.1350 0.1784 0.2049 0.0980 0.2203 3 砾砂 0.9975 0.0052 0.9950 0.0082 0.9757 0.0232 0.9526 0.0361 0.8007 0.0927 0.6676 0.1298 0.2866 0.2145 0.1673 0.2374 4 砾砂 0.9933 0.0076 0.9868 0.0123 0.9371 0.0365 0.8817 0.0569 0.5984 0.1339 0.4270 0.1717 0.1297 0.2301 0.0693 0.2412 5 粉土 0.9970 0.0026 0.9940 0.0043 0.9706 0.0143 0.9429 0.0237 0.7675 0.0684 0.6227 0.0985 0.2482 0.1659 0.1417 0.1834 6 全-强风化砂岩 0.9938 0.0010 0.9878 0.0021 0.9416 0.0112 0.8897 0.0222 0.6173 0.0833 0.4465 0.1235 0.1389 0.1977 0.0746 0.2135 7 含砾粉质粘土 0.9980 0.0006 0.9960 0.0012 0.9804 0.0055 0.9616 0.0105 0.8337 0.0430 0.7148 0.0722 0.3339 0.1627 0.2004 0.1939 8 含砾粉质粘土 0.9937 0.0005 0.9876 0.0012 0.9408 0.0077 0.8882 0.0164 0.6137 0.0711 0.4427 0.1098 0.1371 0.1844 0.0736 0.2005 9 含砾粉质粘土 0.9942 0.0133 0.9885 0.0196 0.9453 0.0470 0.8962 0.0673 0.6333 0.1365 0.4633 0.1690 0.1472 0.2190 0.0795 0.2286 10 含砾粉质粘土 0.9968 0.0066 0.9937 0.0102 0.9692 0.0275 0.9402 0.0416 0.7586 0.0998 0.6111 0.1345 0.2392 0.2049 0.1358 0.2219 11 全-强风化灰岩 0.9862 0.0083 0.9728 0.0138 0.8772 0.0431 0.7812 0.0666 0.4166 0.1397 0.2631 0.1667 0.0666 0.1993 0.0345 0.2045 12 圆砾 0.9872 0.0082 0.9746 0.0136 0.8849 0.0427 0.7935 0.0663 0.4345 0.1415 0.2776 0.1702 0.0714 0.2057 0.0370 0.2114 13 圆砾 0.9975 0.0007 0.9950 0.0014 0.9754 0.0065 0.9520 0.0124 0.7987 0.0494 0.6648 0.0807 0.2840 0.1678 0.1655 0.1944 14 圆砾 0.9941 0.0030 0.9833 0.0053 0.9443 0.0192 0.8945 0.0323 0.6291 0.0902 0.4589 0.1229 0.1450 0.1786 0.0782 0.1900 15 圆砾 0.9979 0.0005 0.9959 0.0011 0.9796 0.0055 0.9601 0.0110 0.8280 0.0493 0.7065 0.0854 0.3249 0.2007 0.1940 0.2407 16 圆砾 0.9912 0.0112 0.9826 0.0174 0.9189 0.0464 0.8499 0.0686 0.5311 0.1417 0.3615 0.1725 0.1017 0.2145 0.0536 0.2217 17 断层泥 0.9956 0.0033 0.9912 0.0058 0.9575 0.0207 0.9184 0.0351 0.6924 0.1030 0.5295 0.1454 0.1837 0.2273 0.1012 0.2458 18 粉质黏土 0.9988 0.0025 0.9975 0.0041 0.9878 0.0124 0.9758 0.0199 0.8897 0.0570 0.8013 0.0856 0.4465 0.1742 0.2874 0.2075 19 粘土 0.9982 0.0005 0.9964 0.0009 0.9821 0.0047 0.9648 0.0092 0.8458 0.0412 0.7328 0.0720 0.3542 0.1760 0.2152 0.2144 20 含砾粉质粘土 0.9989 0.0069 0.9978 0.0101 0.9892 0.0245 0.9787 0.0358 0.9018 0.0835 0.8211 0.1164 0.4786 0.2107 0.3146 0.2453 21 粉质粘土 0.9961 0.0015 0.9922 0.0027 0.9620 0.0111 0.9268 0.0200 0.7170 0.0673 0.5589 0.1002 0.2022 0.1704 0.1125 0.1875 22 粉质粘土 0.9991 0.0034 0.9982 0.0052 0.9913 0.0134 0.9828 0.0201 0.9193 0.0504 0.8507 0.0726 0.5326 0.1430 0.3630 0.1719 23 全-强风化灰岩 0.9941 0.0008 0.9883 0.0018 0.9441 0.0103 0.8940 0.0211 0.6279 0.0858 0.4576 0.1307 0.1444 0.2176 0.0778 0.2366 24 填土 0.960 0.025 0.950 0.028 0.800 0.030 0.700 0.035 0.300 0.080 0.200 0.100 0.150 0.110 0.100 0.120 25 角砾、碎石或卵石 0.990 0.004 0.970 0.006 0.900 0.019 0.850 0.030 0.700 0.075 0.550 0.090 0.320 0.110 0.200 0.120 26 基岩 1.000 0.050 1.000 0.050 1.000 0.050 1.000 0.050 1.000 0.050 1.000 0.050 1.000 0.050 1.000 0.050 注:土类号1—23源于实际实验数据,土类号24—26为《工程场地地震安全性评价工作规范》(DB 001-94)推荐值 表 3 地表水平向地震动峰值加速度及记录峰值加速度比
Table 3. Peak acceleration of horizontal ground motion and recorded peak acceleration ratio
计算模型 峰值加速度/(cm•s−2) 记录峰值加速度比 DZK1 1056.0 1.11 DZK2 742.0 0.78 DZK3 1100.0 1.16 DZK4 449.1 0.47 DZK5 1064.0 1.12 DZK6 1718.0 1.81 -
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