复合加载模式下单桩复合筒型基础地基承载力包络线研究     

刘润  祁越  李宝仁  练继建  丁红岩 《岩土力学》2016,37(5):1486-1496

海上风力发电机属于高耸结构物,其地基基础不仅要承受上部结构传递的竖向荷载V、水平荷载H,更要抵抗巨大的弯矩荷载M。单桩复合筒型基础是新型的海上风力发电机基础型式,建立复合加载模式下单桩复合筒型基础地基的破坏包络线,并据此评价其稳定性是地基基础设计的重要手段。在Swipe加载方法和固定位移比加载方法的基础上,通过数值分析研究了不排水饱和软黏土中单桩复合筒型基础在V-H、V-M、H-M和V-H-M加载模式下的地基承载力包络线,开展了室内模型试验,验证了数值分析结果的可靠性。研究表明,V-H和V-M加载模式下地基承载力包络线具有对称性,而H-M加载模式下呈非对称性;V-H-M加载模式下地基承载力包络线的形状受弯矩荷载M的影响显著,表现为随着弯矩荷载的增加,V-H平面内的破坏包络线逐渐缩小。实际工程中,可根据受力状态与破坏包络面的相对关系,评价单桩复合筒型基础的稳定性。  相似文献   

利用区域地震波形振幅包络约束朝鲜地下核试验的埋深和当量   总被引：2，自引：1，他引：1       下载免费PDF全文

林鑫  姚振兴 《地球物理学报》2016,59(6):2066-2079

核爆当量和埋藏深度是地下核试验的两个重要参数.根据中国东北地区区域范围内地震台站观测记录,利用Pn,Pg,Sn和Lg波波形,计算水平分量的尾波振幅包络,调查2006年10月9日,2009年5月25日,2013年2月13日和2016年1月6日四次朝鲜地下核试验的爆炸当量和埋藏深度.以牡丹江(MDJ)台站记录为例,对两个水平分量波形进行带通滤波,计算平均波形的振幅包络.最终得到区域地震台站水平分量振幅包络,振幅稳定,包络振幅的变化清晰地显示区域震相的位置.区域震相的时间域振幅包络由震源谱函数、传播效应、台基响应和传递函数及尾波形状函数构成.通过网格搜索的方法,拟合水平分量记录的波形包络,可以获得核爆当量和埋藏深度的估计.结果表明,朝鲜四次地下核试验爆炸当量以时间为序从0.6±0.2kt到3.0±1.5kt,增加至10.0±2.0kt,再降到8.0±2.0kt.2006年核爆的埋藏深度较浅,为150±100m,2009年朝鲜核试验的埋藏深度为350±100m,2013年和2016年朝鲜核试验的深度非常一致,均为500±200m.这些结果与前人的调查结果一致性较高,说明使用单一地震台站时间域水平分量尾波振幅包络是可能同时约束地下核试验爆炸当量和埋藏深度的.  相似文献   

面向中尺度涡提取的SLA去噪方法研究     

吴书超  董庆  薛存金  毕经武  廖志宏  宋晚郊 《地球信息科学学报》2016,18(9):1240-1248

噪声去除一直是基于卫星高度计资料的海洋中尺度涡提取研究的难点和热点,然而无论是卷积滤波器还是信息滤波器都存在对海面高度异常（SLA）数据的局部过处理现象。鉴于此,本文提出一种基于包络面去噪的海洋中尺度涡提取方法。该算法可利用分离层内的信息稳定性和层间的信息完备性,很好地改进了卷积运算没有考虑局部噪声的不足,进而有效地提高去噪能力。其具体流程为：首先,对初始化的原始数据场进行上下包络面构造,形成原始数据子场;然后,根据子场内部和子场间的稳健性,把原始数据场转换为子场集合;其次,利用子场极差和标准差,对子场集合进行信息重组,形成噪声去除后的信息场;最后,利用去噪后的信息场数据,采用Winding-Angle（WA）和泛克立金中尺度涡提取算法在西北太平洋进行对比验证实验。实验结果表明,本文提出的方法较前人的方法有较大的提升,准确率为91.23%,取得了较好的应用效果。  相似文献   

Mohr space and its application to the activation prediction of pre-existing weakness     

TONG HengMao  WANG JianJun  ZHAO HaiTao  LI Bo  HAO HuaWu  WANG MingYang 《中国科学:地球科学(英文版)》2014,57(7):1595-1604

The activation coefficient equations in the"activation criterion of pre-existing weakness"are relatively complex and not easy to apply to specific applications.The relative activity of pre-existing weaknesses is often critical in geological analysis.The Mohr circle can be used only in two-dimensional stress analysis.By applying the"activation criterion of pre-existing weakness"and combining it with numerical analysis,we establish the correspondence between the pole(n,n)of a pre-existing weakness plane and its orientation in"Mohr space".As a result,the normal stress(n)and shear stress(n)of a pre-existing weakness plane can be readily expressed in Mohr space.Furthermore,we introduce the method and procedures for predicting the activation and relative activation of pre-existing weaknesses in Mohr space.Finally,we apply the Mohr space method and compare the predictions to sandbox modeling results and 3D seismic data.The results show that Mohr space can be used in stress analysis to estimate the activation of a pre-existing weakness in any triaxial stress state.  相似文献   

Effective use of seismic response envelopes for reinforced concrete structures          下载免费PDF全文

Salvatore Sessa  Francesco Marmo  Luciano Rosati 《地震工程与结构动力学》2015,44(14):2401-2423

By exploiting the theory of the response envelopes formulated by Menun and Der Kiureghian [Envelopes for seismic response vectors. I–Theory, J. Str. Engrg. 2000; 126(3); 467–473], an algorithmic approach for seismic analysis of reinforced concrete frames is presented. It aims to fill a gap between research on spectral analysis of structures and current design practice in which the use of seismic response envelopes, available since early 2000s, is hampered by the lack of efficient and robust implementations. The proposed strategy is based on customary features (such as modal shapes and response spectra) currently adopted in professional practice, and it takes advantage of recently published formulations for the evaluation of stress resultants in arbitrarily shaped reinforced concrete cross‐sections subjected to axial force and biaxial bending. Numerical applications are illustrated in order to show the procedure's efficiency and effectiveness. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

一种提高振动源扫描算法信噪比的方法     

刘双庆  谢静  王熠熙 《华北地震科学》2015,33(1)

在对原始数据进行适当光滑的基础上,利用局部极值特性拟合出数据包络线。经地震波形数据计算检验,利用这种包络线可以较好地提高振动源扫描算法(SSA)的信噪比。而对于无源的随机振动,该方法给出的SSA亮点函数高低值较接近,且亮点函数的高值分布随扫描起始时间及扫描长度的变化与有源信号有较明显差异,这也为评价某时刻点上是否存在有源信号提供了一定的判据。  相似文献   

Evaluation of vertically and laterally loaded bucket foundation in clay using a three-dimensional displacement approach     

Hiroyoshi Hirai 《Marine Georesources & Geotechnology》2013,31(4):452-466

ABSTRACT

An investigation is made to present analytical solutions provided by a three-dimensional displacement approach for analysis of bucket foundations subjected to vertical and lateral loads in cohesive soils. The nonlinear vertical and lateral stiffness coefficients along the skirt of the bucket foundation in nonhomogeneous soil are presented using three-dimensional solutions for vertical and lateral loads and taking into account the dependence of stiffness coefficients on the shear strain. The vertical, lateral, and rocking stiffness coefficients on the base of the skirt of a bucket foundation are obtained from the solutions of hollow rigid cylindrical punch acting on the surface of a soil. The ultimate vertical stress of a soil under the base of a bucket foundation subjected to vertical and moment loads is presented analytically by considering only compression and ignoring tension on the base. The vertical and lateral yields along the skirt and the compression and shear failures on the base are taken into account in analysis of ultimate load capacities. Envelopes of the combined ultimate horizontal and moment load capacities of a bucket foundation in clay are shown. Relationships between ultimate lateral and moment load capacities and the embedment ratio (skirt length to diameter) are presented.  相似文献   

Optical identification and observational study of unidentified IRAS LRS sources. 2. Observations of sources with the silicate feature in the 13–24northern sky region     

Wang Jun-jie  Jiang Bi-wei  Hu Jing-yao   《Chinese Astronomy and Astrophysics》1994,18(4):429-434

JHK photometry was carried out for some of the sources with the silicate feature in the sky region 13^h < < 24^h, 0° < δ < 66° and a discussion on several peculiar objects was made.  相似文献   

高分辨率η模式暴雨个例的数值模拟     

周祖刚  张维桓等 《气象科学》2001,21(4):452-461

本文运用高分辨率η坐标模式，并采用常规报文资料获得初始场，运用包络地形方法获得模式所需的地形资料，对1993－1997年5－8月主要暴雨个例进行了数值模拟，结果表明，该模式对降水场、形势场的模拟较好，TS评分较高，模式对暴雨有一定的模拟能力。  相似文献   

切变基本纬向流中赤道Rossby包络孤立波          下载免费PDF全文

赵强  刘式适 《大气科学》2001,25(1):133-141

利用多重尺度摄动法，从描写赤道Rossby波的正压大气位涡度方程中推导出在切变基本纬向流中非线性赤道Rossby波包演变所满足的非线性Schrodinger方程，并得到其单个包络孤立子波解，分析基本流切变对非线性赤道Rossby波动的影响。  相似文献