天津滨海地区浅层剪切波速与基底构造关系研究

Shear wave velocity is one of the important dynamic characteristics of soil layers and applied widely in aseismic engineering. In this paper, 500 drill logging data are used to make a linear interpolation based on 0.01°×0.01°×1m grid. A shallow 3-D shear wave velocity structure of Tianjin coastal area is obtained. According to the data and geological background, we selected two typical velocity profiles to try to introduce and explain its relationship to basement structure. The results show that the shear wave velocity structure clearly presents the characteristic of stratification and lateral inhomogeneity. Furthermore, the difference of the shear wave structure between tectonic elements is clear and the velocity structure between the two sides of the local or border fault in the Quaternary is disturbed or affected significantly. It intuitively shows that the basement structure and fault activity of this region had good control of sedimentation development and strata formation in the Quaternary period which would have an important effect on engineering seismic and geological condition evaluation.     

钢筋混凝土剪力墙非线性单元模型的研究

本文首先对等效框架模型、多竖直杆单元模型作了改进.然后应用改进等效框架模型、改进多竖直杆单元模型及分层壳单元模型,对不同轴压比的三片剪力墙构件模型与一个14层筒中筒结构模型进行了计算分析,并与实验结果作了比较.结果表明:改进多竖直杆单元模型在所有情况下均可取得较好结果,是适用性较强的剪力墙非线性单元模型;多层壳单元模型...     

新型开孔H型钢阻尼器有限元分析

设计了分别开椭圆形孔和菱形孔的2种新型H型钢耗能器,阐述了它们的构造与耗能原理。采用有限元软件ABAQUS对开椭圆形孔、菱形孔和条形孔这3种新型耗能器的耗能性能进行数值分析,研究了开孔形状、肢宽与肢高等参数对新型耗能器耗能性能的影响。分析结果表明：新型H型钢耗能器具有饱满的滞回曲线,屈服位移较小、耗能性能稳定,耗能器的屈服位移、初始刚度和等效阻尼比随各肢钢板宽度增大（或高度减小）而增大;在开孔率相近或者肢宽相同的情况下,菱形孔H型钢耗能器的等效阻尼比要比条形孔和椭圆形孔的大,且应力分布更加均匀。     

方钢管混凝土柱-钢梁平面框架耐火性能研究

建立了局部火灾下多层多跨矩形钢管混凝土柱-钢梁平面框架温度场和力学性能分析的有限元模型。在考虑楼板影响的基础上,研究了保护层厚度不同时钢管混凝土框架结构的温度场分布规律。研究了不同受火工况条件下钢管混凝土框架结构的变形和破坏规律、耐火极限状态、受火梁的内力状态以及结构耐火极限的规律。分析表明,梁保护层厚度影响钢梁温度分布形式;火灾下,框架结构发生了受火梁的整体屈曲破坏。     

基于全区视电阻率的线源FCSEM二维正演模拟

频率域可控源电磁是在大地电磁测深的基础上发展起来的一种人工源电磁测深法,其二维电磁响应的计算须采用数值模拟方法.本文以Matlab为程序编译工具,采用双二次插值的有限单元法,推导出相应的计算公式.为了模拟无穷远边界及满足计算机的内存需求,在保证计算精度的情况下设计了非均匀网格剖分.在程序编制中,只存储有限元系数矩阵的非零元素,大大减少了正演计算的时间.针对频率域可控源电磁法中卡尼亚电阻率在过渡区和近区畸变的问题,给出了全区视电阻率的迭代公式,并对典型的一维层状模型以及简单二维模型进行了计算.过渡区和近区数据经过校正后,可以正确反映出模型的地电特征,证明了线源下近区勘探的可能性.     

单调及低周往复荷载作用下砌体非线性分析

带构造柱和圈梁的约束砌体结构在四川灾区乡镇房屋重建中被广泛采用,其抗震性能是人们所关心的.基于绵竹市土门镇当地重建房屋常用建筑材料的实验数据以及通用有限元软件ANSYS中Solid 65单元的性质和特点,用有限元模型模拟了粘土砖砌体在不同压应力状态(σ-/fm)下沿通缝截面抗剪强度试验,给出了相关单元在模拟砖砌体开裂中闭合及开口剪力传递系数的建议值;利用这些结果,分别建立了带约束(构造柱、圈梁等)和不带约束砌体墙的有限元模型,进而分析了他们在单调荷载以及低周往复荷载作用下的抗震性能.结果表明,与不带约束的墙体相比,带约束墙体在单调水平荷载作用下的初裂性能、极值荷载和延性都有很大的提高,在低周往复荷载作用下其耗能能力得到了改善.所得结果可供相应结构抗震设计的参考.     

An elastic-plastic analysis of short-leg shear wall structures during earthquakes

Short-leg shear wall structures are a new form of building structure that combine the merits of both frame and shear wall structures. Its architectural features, structure bearing and engineering cost are reasonable. To analyze the elastic-plastic response of a short-leg shear wall structure during an earthquake, this study modified the multiple-vertical-rod element model of the shear wall, considered the shear lag effect and proposed a multiple-vertical-rod element coupling beam model with a new local stiffness domain. Based on the principle of minimum potential energy and the variational principle, the stiffness matrixes of a short-leg shear wall and a coupling beam are derived in this study. Furthermore, the bending shear correlation for the analysis of different parameters to describe the structure, such as the beam height to span ratio, short-leg shear wall height to thickness ratio, and steel ratio are introduced. The results show that the height to span ratio directly affects the structural integrity; and the short-leg shear wall height to thickness ratio should be limited to a range of approximately 6.0 to 7.0. The design of short-leg shear walls should be in accordance with the "strong wall and weak beam" principle.     

Amplification of in-plane seismic ground motion by group cavities in layered half-space (Ⅰ)

Amplification of in-plane seismic ground motion by underground group cavities in layered half-space is studied both in frequency domain and time domain by using indirect boundary element method (IBEM), and the effect of cavity interval and spectrum of incident waves on the amplification are studied by numerical examples. It is shown that there may be large interaction between cavities, and group cavities with certain intervals may have significant amplification to seismic ground motion. The amplification of PGA (peak ground acceleration) and its PRS (peak response spectrum) can be increased up to 45.2% and 84.4%, for an example site in Tianjin, under the excitation of Taft wave and El Centro wave; and group cavities may also affect the spectra of the seismic ground motion. It is suggested that the effect of underground group cavities on design seismic ground motion should be considered.     

山东半岛东部海域表层沉积物元素组成及物源指示意义

通过对山东半岛东部海域表层沉积物常量、微量元素、有机碳(TOC)以及碳酸盐(CaCO₃)等指标的分析,研究了该海域表层沉积物元素组成特征及其控制因素,并对物质来源进行了探讨。结果表明,山东半岛东部海域表层沉积物元素的平均组成与上陆壳(UCC)相比Al,K,Na,Mg,Fe,Ca,Cu和Zn等元素,相对较低,而Mn,Co,Ni,Cr以及REE元素含量较高,Si和Ti与UCC的含量相当。研究区砂粒级沉积物轻重稀土分异明显,(La/Yb)_N值与韩国河流的非常相近;其余粒级沉积物LREE分异较弱,标准化曲线与黄河沉积物的具有相似性。研究区沉积物的元素含量主要受控于源岩组成,存在明显的"粒级效应"。除此之外,Fe-Mn氧化物、生物碳酸盐等因素对元素组成产生一定影响。沉积物物源判别结果显示,山东半岛近岸及其东南部沉积物主要来源于黄河,该区域沉积物分布受山东半岛沿岸流及近岸潮流影响。研究区东北部为残留砂,其沉积物元素组成特征与朝鲜半岛和鸭绿江沉积物组成相近,表明研究区东北部砂质区沉积物代末次冰期低海平面时可能由朝鲜半岛或鸭绿江供应。     

基于模糊聚类分析的莱州湾南岸地下水化学分布特征研究

针对莱州湾南岸咸水入侵区地下水质连续、渐变和边界模糊的特征,利用规格化变换对莱州湾南岸地下水化学组分数据进行标准化,采用夹角余弦法作为相似系数,用平方法计算传递闭包构造模糊等价矩阵进行模糊聚类分析,将莱州湾南岸地下水划分为3类并绘制其平面分区图.在此基础上,用探索性数据分析技术的箱线图分别识别各类地下水各组分的分位数、中位数、极值等数据分布情况,并结合 Radial 图绘制各类地下水各组分均值;利用基于 CA 舒卡列夫分类方法的 Piper三线图识别了各类地下水的水化学类型;最后在相关分析基础上选取代表性指标绘制等值线图,结合模糊聚类分区探讨了分区各指标的空间结构特征及内在机理.综合上述分析,定义玉区为海水入侵重点治理区,域区为海水入侵综合防范与整治区,芋区为卤水区.