论攵 作 者 签名 ∴ TAR烬 l 仂 l徉 J月y日论文知识产权权属声明本人在导师指导下所完成的论文及相关的职务作品 ,知 识产权归属学校。学校享有以任何方式发表、复制 (公 开阅览、借∷ 阅以及申请专利等权利。本人离校后发表或使用学位论文或与该论文直接相关的学术论文或成果时 ,署 名单位仍然为长安大学。(保 密的论文在解密后应遵守此规定 ) ∷论文作者签名 : 取沮 l γ l孑 年 ‘ 月ˇ 日钿 l孑 年 ‘月 y日 i摘 要剪切波速既能反映岩土的动力特性,又能反映岩土的刚度特征,其在岩土工程勘察和岩土抗震领域中具有广泛的应用。在实际工程中,土层的剪切波速通常需由现场实测结果来确定,但对剪切波速进行实测时,由于原位测试方法和场地条件等的限制,往往得不到理想的剪切波速资料。很多研究证明,剪切波速与深度之间具有很强的相关性,并且剪切波速的分布规律带有明显的地域特征。因此,利用已有的剪切波速资料,结合当地的地质条件,统计剪切波速随深度的分布特征及变化规律,将会为当地场地的岩土勘察和岩土抗震设计工作提供重要的参考依据。本文利用西安地震小区划和西安地铁三号线地震安评工作中共 108 个深孔(90 米)和 402 个浅孔(30 米)的原位剪切波速测试数据,基于直接法分别按工程地质分区和岩土类型统计剪切波速与深度的关系。此外,基于 30 米深度内的剪切波速资料,利用间接法进行统计分析,并与对应的直接法结果进行了对比。通过统计分析,得到了如下结论:1、根据西安地震小区划的工程地质分区情况,利用直接法对具有相似土体结构的各地质亚区进行剪切波速与深度的统计分析,并分为 30 米和 90 米统计区间,建立了不同工程地质分区剪切波速与深度的经验关系式。其中 30 米深度范围内,剪切波速随深度的变化趋势满足幂函数、复杂幂函数或二次函数关系;90 米深度范围内,剪切波速随深度的变化趋势满足四次、五次多项式或分段函数关系。2、对于西安地区常见的岩土类型,利用直接法对三大工程地质分区中的不同土类进行分类统计,并分为 30 米和 90 米统计区间,得到相应的最优回归模型、回归参数及其适用的深度范围,建立了不同土类剪切波速与深度的经验关系式。其中 30 米深度范围内,剪切波速随深度的变化趋势满足线性函数、幂函数、复杂幂函数或二次函数关系;90 米深度范围内,剪切波速随深度的变化趋势满足三次、四次、五次多项式或分段函数关系。3、通过间接法统计结果发现,走时与深度具有很强的相关性,可用幂函数和对数函数模型描述其关系,且幂函数拟合精度高于对数函数模型,相对应的深度-剪切波速关系,则是幂函数模型优于线性函数模型。通过间接法与直接法结果的对比分析,发现无论幂函数还是线性函数,两方法的结果之间存在一定差距,且线性模型大于幂函数模型。对于幂函数模型,在浅地表,两方法结果基本重合;到 10~15m 后,直接法结果大 ii于间接法。对于线性函数,在浅地表,直接法结果大于间接法;到 10~15m 后,间接法结果大于直接法结果。关键词 :剪切波速;深度;经验关系式;直接法;间接法; iiiAbstractShear wave velocity, which has a wide applications in geotechnical investigation andearthquake engineering, can not only reflect the dynamic characteristic, but also reflect therigidity characteristic of rock and soil. In practical projects, the shear wave velocity of the soillayer is usually measured by in-situ test. However, during the measurement of shear wavevelocity, there are not the ideal velocity values because of the limitations of in-situ testingmethods and site conditions. Many studies have shown that there is a strong correlationbetween shear wave velocity and depth, and the distribution of shear wave velocity hasobvious region characteristic. Therefore, using existing shear wave data and combining withlocal geological conditions, the relationship between shear wave velocity and depth analysedby statistical method will provide an important reference for geotechnical investigation andgeotechnical seismic design of the local area.Using the in-situ data from 108 deep holes (90 meters) and 402 shallow holes (30 meters)from Xi'an Seismic mico-zoing and Xi'an Metro Line 3 seismic safety evaluation, theempirical correlation of shear wave velocity and depth is established considering theengineering geological zoning and rock and soil types respectively by means of direct method.In addition, using the shear wave velocity data within a depth of 30 meters, the paper analysesthe relationship of velocity and depth by indirect method, and then compares the indirectmethod results with the corresponding direct method results. Through statistical analysis, thefollowing conclusions have been acquired:1. According to the engineering geological zoning of Xi'an sesmic micro-zoning, therelationship of the shear wave velocity and depth of each geological zoning with similar soilstructure is analysed by direct method, and the empirical formulas are gived out in 30-meterand 90-meter statistical intervals respectively. In the depth range of 30 meters, the variationtrend of the shear wave velocity with depth satisfies the power-law function, complexpower-law function or quadratic polynomial function. In the depth range of 90 meters, thevariation trend of the shear wave velocity with depth satisfies the quartic polynomial, quanticpolynomial or precewise function relations.2. For the common rock and soil types of Xi'an area, the relationship of shear wavevelocity and depth of the difference soils in three major geological zoning is classified toanalyse by direct method. It obtained the optimal models, parameters and range of depthappliance, and the empirical formulas are established in 30-meter and 90-meter statisticalintervals respectively. In the depth range of 30 meters, the variation trend of the shear wave ivvelocity with depth satisfies the liner, power-law, complex power-law or quadratic polynomialfunction. In the depth range of 90 meters, the variation trend of the shear wave velocity withdepth satisfies the cubic polynomial, quartic polynomial, quintic polynomial or precewisefunction relations.3. The statistical results of indirect method show that travel time and depth have a strongcorrelation which can be described by a power-law and logarithmic model, and the powerfunction’fitting accuracy is higher than the logarithmic function model. And thecorresponding relationship of depth-shear wave velocity is that the power function model issuperior to the linear function model. Through the comparison between the indirect methodand the direct method, it’s found that there is a certain gap between the two methods,regardless of the power function or the linear function. And the gap of linear model is largerthan the power function model. For the power-law model, in the shallow surface, the result ofthe two methods basically coincide; after 10 to 15 m, the direct method result is larger thanthe indirect method. For linear model, the direct method result is larger than the indirectmethod at shallow surface, and after 10 to 15 meters, the result of indirect method is largerthan the direct method.Key words: Shear wave velocity; Depth; Empirical relationship; Direct method; Indirectmethod; v目录第一章 绪论...............................................................................................................................11.1 问题的提出及研究意义..............................................................................................11.2 剪切波速与深度关系研究现状..................................................................................11.2.1 剪切波速的测试方法.......................................................................................21.2.2 直接构造法.......................................................................................................31.2.3 间接构造法.......................................................................................................91.3 主要研究内容.............................................................................................................10第二章 基于直接法的剪切波速与深度关系研究.................................................................112.1 引言............................................................................................................................112.2 回归分析原理............................................................................................................112.2.1 回归方程的建立.............................................................................................112.2.2 回归方程的评价.............................................................................................142.2.3 统计检验.........................................................................................................152.3 西安地层及工程地质分区情况................................................................................162.3.1 西安地层情况.................................................................................................162.3.2 西安工程地质分区情况.................................................................................172.4 数据来源与选取原则................................................................................................182.5 不同工程地质分区剪切波速与深度关系分析........................................................182.5.1 30 米深度内剪切波速的统计分析.................................................................182.5.2 90 米深度内剪切波速的统计分析.................................................................232.6 不同岩土类型剪切波速与深度关系分析................................................................282.6.1 30 米深度内剪切波速统计分析.....................................................................292.6.2 90 米深度内剪切波速统计分析.....................................................................332.7 本章小结....................................................................................................................39第三章 基于间接法的剪切波速与深度关系研究.................................................................403.1 引言............................................................................................................................403.2 间接法原理................................................................................................................40 vi3.3 间接法统计结果分析................................................................................................413.4 间接法与直接法结果的对比....................................................................................453.5 本章小结....................................................................................................................50第四章 结论与展望.................................................................................................................514.1 结论............................................................................................................................514.2 展望............................................................................................................................54参考文献...................................................................................................................................56攻读学位期间取得的研究成果...............................................................................................59致谢...........................................................................................................................................60 第一章 绪论1第一章 绪论1.1 问题的提出及研究意义剪切波速是指地震横波在岩土体内的传播速度,它的大小既反映了岩土的动力特性,又反映了岩土层的刚度特征,其在岩土地震工程中具有广泛的应用。我国《建筑抗震设计规范》(GB50011—2010)中提供的场地分类标准是“双指标法”:土层等效剪切波速和场地覆盖层厚度,其中覆盖层厚度也需剪切波速值来确定;同时该规范还规定把剪切波速值作为划分土的类型和软硬程度的标准 [1] 。《工程场地地震安全性评价》(GB17741-2005)推荐的土层地震反应分析方法仍需利用土层的剪切波速资料 [2] 。此外,剪切波速能判别饱和砂土和粉土地震液化的可能性,可以计算场地土层的力学参数以及场地的卓越周期,并且在地震小区划工作中,也是不可缺少的基本参数 [3-5] 。在多数重要工程中,土层剪切波速值通常需由现场实测结果来确定。剪切波速的测试方法一般有单孔法、跨孔法和面波法 [6] 。采用跨孔法时,测试过程中至少需要 2 个钻孔,钻孔间的距离不宜过大,并且对钻孔倾斜度的要求非常高,因此在实际工程中较少使用。采用面波法测量时,得到的结果是混合反射波、折射波以及直达波等多种干扰波的瑞利波速,并且要通过统计公式转化得到剪切波速,属于间接测量法,可能导致较大的误差。