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1.
基于等效线性化的一维土层地震反应计算是目前国内外普遍采用的方法，国外的SHAKE91、DEEPSOIL和我国的LSSRLI-1即是根据这一方法编制的通用计算程序。本文采用这3个程序进行了不同地震波、不同输入地震动幅值下不同场地类型的土层地震反应计算，并对三者的结果进行了全面的比较分析。结果表明:①SHAKE91和DEEPSOIL程序的计算结果完全相同；②当土层最大剪应变均采用时域计算时，LSSRLI-1程序的计算结果与SHAKE91和DEEPSOIL程序基本相同，但有微小差别，其原因是:在基于等效剪应变通过离散形式的剪切模量和阻尼比随等效剪应变变化的关系曲线确定等效剪切模量和阻尼比时，DEEPSOIL和SHAKE91采用的插值方法与LSSRLI-1不同；③当LSSRLI-1程序采用频域经验关系计算土层最大剪应变时，特别是在强地震动输入下得到的土层地表加速度峰值和加速度反应谱与另外两个程序的计算结果有差别，且土层最大剪应变随着输入加速度的增大出现较大的差别。因此，本文建议:当采用LSSRLI-1程序计算土层地震响应时，应使用程序中的时域解方法代替以往默认的频域经验关系方法。 相似文献
2.
剪切波速对场地地表地震动参数的影响 总被引：3，自引：2，他引：1
本文以江淮地区典型场地资料为原型,将土层剪切波速实测值按照一定比例进行增减,构造多种场地土层地震反应分析模型,选择Taft、E1centro和Kobe三条强震记录作为地震输入,采用一维频域等效线性化波动方法进行了土层地震反应分析.研究结果表明,剪切波速的变异性与场地地表地震动的影响程度与输入基岩地震动的频谱特性、幅值、土层结构等因素有关.地表峰值加速度随着剪切波速的增大而逐渐增大,地表加速度反应谱的特征周期随着剪切波速的增大而逐渐减小. 相似文献
3.
为了评价4种等效线性场地响应软件的适用性,选取深厚场地作为研究对象,将基岩地震波作为地震输入,根据土层剪切波波速和容重确定初始剪切模量并设置对应的模量衰减和阻尼比曲线,分别用SHAKE 2000、 DEEPSOIL、EERA和Strata 4种等效线性场地响应程序计算得到地表的加速度时程及相应的加速度反应谱和傅里叶幅值谱\,场地的最大剪应变和峰值加速度随深度的变化曲线。计算结果表明,由4种场地响应软件得到的地表加速度时程对应的加速度反应谱和傅里叶幅值谱一致,由于土层划分方式不同,Strata软件得到的峰值加速度和最大剪应变深度曲线不同。总结4种软件的不同,DEEPSOIL可以较全面考虑土的动力特性,Strata提供随机振动理论进行场地响应分析并可以考虑土层参数的变异性。 相似文献
4.
基于谐波入射下的波动理论频域精确解,导出线性时域精确解,并在Matlab环境中编制相应的计算程序;选取8个简化的中硬场地剖面,用LSSRLI-1、精确解和SHAKE2000三种方法计算各场地在不同输入条件下的地震反应。结果表明:程序计算所得地表反应谱和土体剪应变分布与SHAKE2000结果一致;LSSRLI-1方法得到的地表反应谱与前二者结果一致;LSSRLI-1方法在某些情况下得到的土体剪应变分布与另外二者结果存在较大偏差,该偏差对地表反应谱有着不可忽略甚至非常显著的影响。 相似文献
5.
以日本KiK-net强震观测台网中硬场地井下记录为样本，对传统等效线性化方法LSSRLI-1（频域）、SHAKE2000，时域非线性方法DEEPSOIL和频域一致等效线性化方法SOILQUAKE等几种计算程序在硬土场地地震反应分析中的可靠性进行对比检验。检验工况包括KiK-net井下台网中地表峰值加速度不小于0.05g的水平硬场地的总计344台次的加速度记录，涉及5个台站，土层厚度6~50m，地表峰值加速度范围0.050~0.805g。结果表明:认为硬土场地以往计算方法能够体现土层放大的认识是片面的，在中强地震动情况下，现有流行方法计算出的地表响应会偏小，强地震动下会严重偏小，会给工程抗震设计提供偏于危险的输入；硬场地中烈度8度以下（地表PGA在0.19g以下），SHAKE2000和DEEPSOIL、LSSRLI-1（频域）计算结果与实际记录差距可以接受，但烈度8度以上，计算出地表响应均较实际记录明显偏小，且随地震动强度增加差距急剧增大；硬场地中，无论何种烈度，SOILQUAKE16计算的地表加速度响应与实测相当，可体现出土层放大作用。 相似文献
6.
A one-dimensional equivalent linear method (EQL) is widely used in estimating seismic ground response. For this method, the shear modulus and damping ratio of inelastic soil are supposed to be frequency independent. However, historical earthquake records and laboratory test results indicate that nonlinear soil behavior is frequency-dependent. Several frequency-dependent equivalent linear methods (FDEQL) related to the Fourier amplitude of shear strain time history have been developed to take into account the frequency-dependent soil behavior. Furthermore, the shear strain threshold plays an important role in soil behavior. For shear strains below the elastic shear strain threshold, soil behaves essentially as a linear elastic material. To consider the effect of elastic-shear-strain-threshold- and frequency-dependent soil behavior on wave propagation, the shear-strain-threshold- and frequency-dependent equivalent linear method (TFDEQL) is proposed. A series of analyses is implemented for EQL, FDEQL, and TFDEQL methods. Results show that elastic-shear-strain-threshold- and frequency-dependent soil behavior plays a great influence on the computed site response, especially for the high-frequency band. Also, the effect of elastic-strain-threshold- and frequency-dependent soil behavior on the site response is analyzed from relatively weak to strong input motion, and results show that the effect is more pronounced as input motion goes from weak to strong. 相似文献
7.
地震反应分析中输入界面选取合理与否对设计地震动参数有重要影响。基于唐山地区钻孔剖面,分别选取剪切波速为500m/s的硬黏土和800m/s的岩石顶面作为基岩输入界面,采用一维等效线性化方法讨论中硬场地输入界面的选取对地表地震动参数的影响,结果表明:(1)地表峰值加速度放大倍数及地表加速度反应谱特征周期都随输入界面深度的增加而递增,且这种递增与输入地震动的强度及频谱特性都有密切联系;(2)随着输入界面深度的增加,地表加速度反应谱几乎全频段内增大,仅在短周期内出现减小的情况,但幅度十分有限;(3)中硬场地地震反应分析中基岩输入界面宜取剪切波速为800m/s的土层顶面。 相似文献
8.
A statistical approach is proposed for nonlinear surface ground analysis. In contrast to the conventional method which deals with only a single ground motion for equivalent linearization of soil properties, a design response spectrum defined at the upper level (bottom of the surface ground) of an engineering bedrock can be handled as the target design earthquake in the present paper. The effective shear strain in each soil layer is evaluated by means of a statistical procedure in which the mean peak shear strain is computed in terms of its standard deviation and the corresponding peak factor. The stiffness and damping ratio of each soil layer are obtained iteratively from the nonlinear relation of stiffness reduction factors and damping ratios with respect to the strain level. After the evaluation of the equivalent stiffness and damping ratio of every soil layer, the ground surface response spectrum is transformed from the design response spectrum defined at the upper level of the engineering bedrock via the one-dimensional wave propagation theory. The reliability and accuracy of the proposed analysis method is examined through the comparison with the results by the conventional method (represented by the
program) for many simulated spectrum-compatible ground motions. 相似文献
9.
地震动强度及频谱特征对场地地震反应分析结果的影响. 总被引：4，自引：3，他引：1
通过收集整理235个实际钻孔资料并建立了2820个计算工况,运用一维波动等效线性化地震反应分析方法,基于不同类别场地条件,研究在不同强度、频谱特性的地震动输入形式下,场地条件对地表地震动参数影响,重点考察地表峰值加速度的变化特征及规律,并对计算结果进行了统计回归分析,给出了不同场地类别条件下地表峰值放大倍数的一般经验值.由于我国现行抗震设计规范中,没有考虑地震烈度或地震动强度对设计反应谱的影响,也没有考虑地震动频谱特性对地表峰值的影响,因此,本文的研究成果可为未来修订抗震设计规范提供参考依据. 相似文献
10.
M. Kawano K. Asano H. Dohi S. Matsuda 《Soil Dynamics and Earthquake Engineering》2000,20(5-8):493-507
The linear and non-linear responses of surface soil layers have been predicted through the simultaneous simulation test against the observed ground motions at the six sites in Kobe City during the 1995 Hyogo-ken Nanbu earthquake. The total stress analysis method and the effective stress analysis method have been applied for the rough and detailed verification of the predicted non-linear dynamic behavior at the PIS and RKI sites including the liquefaction phenomenon. The shear strain distribution along depth, the ratio of excess pore water pressure to initial effective stress, the liquefaction strength parameters to initial effective stress, and the stress–strain curve during the earthquake at the PIS site have been investigated when the predicted ground motion could simulate successfully the observed acceleration time histories and response spectra in the non-linear range. 相似文献