挡土墙地震反应非线性波动模拟   总被引：3，自引：0，他引：3  

陈学良  袁一凡 《地震工程与工程振动》2003,23(4):9-16

本文运用解耦近场非线性波动数值模拟方法研究挡土墙地震反应，为反映墙土体系在地震作用下的位移机制，引入了Desai薄层单元模拟墙土间接触面，并采用双线型本构关系作为接触面单元和土体的非线性模型，在此基础上给出了解决P—SV问题的非线性显式有限元时域递推公式，为进一步发展非线性波动数值模拟技术提供了有益经验。为验证本文方法及适用性，将数值模拟结果与Zeng，X．和Madabhushi，X．P．G．等的离心机试验和弹塑性数值模拟结果进行对比。结果表明：墙土体系加速度、挡土墙顶底相对滑移、沉降和墙体倾角等同离心机试验模拟结果基本吻合，与弹塑性数值模拟结果相似。  相似文献   

湿地水文学研究进展   总被引：36，自引：4，他引：36       下载免费PDF全文

邓伟  潘响亮  栾兆擎 《水科学进展》2003,14(4):521-527

水文过程在湿地形成、发育、演替直至消亡全过程中起重要作用.降水截流、径流和蒸散作用是湿地 大气界面水文过程研究的热点和重点,开发的模型较多但尚需进一步检验和完善.片流和明渠流是湿地主要地表径流,其中片流受地形坡度等因素影响而难以精确计算.湿地的地下水文系统对季节性积水湿地尤为重要,但是关于泥炭沼泽的垂向水力联系尚需进一步研究.可持续的湿地水文管理必须将人类活动和气候变化这两个因素纳入湿地综合水文模型,然而目前除少数几个综合模型外,大多数的湿地水文模型并非如此.加强湿地水文观测、多手段多技术相结合和开发综合湿地水文模型应是今后湿地水文学研究的主流.  相似文献   

VB实现工艺图纸设计自动化的关键技术     

王建勤  刘威鑫  杨绍国 《物探化探计算技术》2003,25(1):92-96

介绍了用ActiveX接口以及Visual Basic6．O编程开发AotoCAD的原理，并对实现计算机辅助工艺设计中，工艺图纸设计自动化的几个关键技术的开发原理，如工艺草图零部件图形的装配、尺寸标注和标题栏与明细表内客的填写等进行了说明，并提供了采用VB实现的方法和具体代码。  相似文献   

非线性接触力学模型在地基-基础相互作用弹性分析中的应用     

范静海  栾茂田  黎勇  叶祥记 《岩土力学》2004,25(Z2):154-159

针对多体相互作用体系的非连续变形分析问题和接触问题,采用Mohr-Coulomb屈服准则和关联流动法则以及接触界面上的非线性应力分布模式,考虑接触界面特性提出了非线性接触力元模型,以结点位移和界面相互接触应力同时作为独立未知变量,建立了离散系统的总体控制方程.进而,通过数值求解能够直接确定变形体内的应力与变形、界面上的接触应力与离散体的位移与运动.将这种以接触力元为基础的多体系统分析方法具体应用于基础与地基相互作用分析,通过数值计算与分析探讨了地基与基础的相对刚度、荷载大小及其偏心距、地基与基础间界面力学参数对接触界面的应力分布和地基变形的影响,所得结果为工程中考虑基础与地基相互作用影响的设计与分析提供了参考依据.  相似文献   

Comminution and fluidization of granular fault materials: implications for fault slip behavior     

Nobuaki Monzawa  Kenshiro Otsuki   《Tectonophysics》2003,367(1-2):127-143

Whilst faulting in the shallow crust is inevitably associated with comminution of rocks, the mechanical properties of the comminuted granular materials themselves affect the slip behavior of faults. Therefore, the mechanical behavior of any fault progresses along an evolutionary path. We analyzed granular fault rocks from four faults, and deduced an evolutionary trend of fractal size frequency. Comminution of fault rocks starts at a fractal dimension close to 1.5 (2-D measurement), at which a given grain is supported by the maximum number of grains attainable and hence is at its strongest. As comminution proceeds, the fractal dimension increases, and hence comminution itself is a slip weakening mechanism. Under the appropriate conditions, comminuted granular materials may be fluidized during seismic slip events. In this paper, we develop a new method to identify the granular fault rocks that have experienced fluidization, where the detection probability of fragmented counterparts is a key parameter. This method was applied to four fault rock samples and a successful result was obtained. Knowledge from powder technology teaches us that the volume fraction of grains normalized by maximum volume fraction attainable is the most important parameter for dynamic properties of granular materials, and once granular fault materials are fluidized, the fault plane becomes nearly frictionless. A small decrease in the normalized volume fraction of grains from 1 is a necessary condition for the phase transition to fluidization from the deformation mechanism governed by grain friction and crushing by contact stresses. This condition can be realized only when shearing proceeds under unconstrained conditions, and this demands that the gap between fault walls is widened. Normal interface vibration proposed by Brune et al. [Tectonophysics 218 (1993) 59] appears to be the most appropriate cause of this, and we presented two lines of field evidence that support this mechanism to work in nature.  相似文献   

Numerical modelling of seismic waves scattered by hydrofractures: application of the indirect boundary element method   总被引：2，自引：0，他引：2  

Tim Pointer  Enru Liu  & John A. Hudson 《Geophysical Journal International》1998,135(1):289-303

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鲁西寒武系层序地层特征及在区调中的应用     

胡树庭  陈建强  王训练  周洪瑞  杜子图  张成基 《山东国土资源》1998,(4)

鲁西地区寒武纪地层发育较好,沉积记录具旋回性的特点。根据层序地层学的原理与方法,按照不同的层序界面类型、岩石组合特点及沉积相序叠置关系,在该区寒武系中识别出１５个三级层序界面,划分出１４个三级层序（—Ｃ１～—Ｃ１４）。这些层序的共同特点是海侵体系域和高水位体系域发育较好,而典型的低水位体系域则未见及。通过分析海平面的变化规律及其延续时限,它们被归并为两个中层序（ＭＳ１、ＭＳ２）,分别对应于二级海平面变化旋回和碳酸盐台地的两个发育阶段。  相似文献   

赣东北白垩纪盆地等时性地层界面识别及意义     

张志  薛重生  赵良政  王京名 《国土资源遥感》1998,9(2):33-10

笔者在进行赣东北江南造山带印支-燕山碰撞造山后陆内变形演化与信江盆地充填系列研究中,利用TM遥感图像影像信息结合沉积建造分析,对白垩纪盆地中等时性地层界面进行识别与研究。本次识别的等时性地层界面类型有:古构造面、大面积冲蚀不整合界面、大面积超覆界面。这些界面的识别,从整体上保证了盆地沉积相三维空间配置的可靠性,为重塑盆地充填系列及构造演化阶段提供了新的信息。该方法丰富了陆相盆地分析的方法技术,可推动1:5万区调中陆相盆地双重制图方法体系的建立。  相似文献   

Behavior Mechanism on Sulfide Solid-Liquid Interface and Its Application     

Jia Jianye 《中国地质大学学报(英文版)》1998,9(3):2

Ｓｕｒｆａｃｅｍｉｎｅｒａｌｏｇｙｉｓｏｎｅｏｆｔｈｅｍｏｄｅｒｎｂｒａｎｃｈｅｓｏｆｍｉｎ－ｅｒａｌｏｇｙ．Ｔｈｅｒｅｓｅａｒｃｈｏｆｔｈｅｉｎｔｅｒｆａｃｅｏｆｍｉｎｅｒａｌ－ｌｉｑｕｉｄ,ｎａｍｅｌｙｔｈｅｓｔｕｄｙｏｎｔｈｅｒｅａｃｔｉｏｎｏ...  相似文献   

Two-step interface and velocity inversion     

Xiao-Ling Lai  Xian-Kang Zhang  Xu-Yao Zheng 《地震学报(英文版)》1998,11(6):687-697

This paper studies the computation method of two-step inversion of interface and velocity in a region. The 3-D interface is described by a segmented incomplete polynomial; while the reconstruction of 3-D velocity is accomplished by the principle of least squares in functional space. The computation is carried out in two steps. The first step is to inverse the shape of 3-D interface; while the second step is to do 3-D velocity inversion by distributing the remaining residual errors of travel time in accordance with their weights. The data of seismic sounding in the Tangshan-Luanxian seismic region are processed, from which the 3-D structural form in depth of the Tangshan seismic region and the 3-D velocity distribution in the crust below the Tangshan-Luanxian seismic region are obtained. The result shows that the deep 3-D structure in the Tangshan seismic region trends NE on the whole and the structure sandwiched between the NE-trending Fengtai-Yejituo fault and the NE-trending Tangshan fault is an uplifted zone of the Moho. In the 3-D velocity structure of middle-lower crust below that region, there is an obvious belt of low-velocity anomaly to exist along the NE-trending Tangshan fault, the position of which tallies with that of the Tangshan seismicity belt. The larger block of low-velocity anomaly near Shaheyi corresponds to a denser earthquake distribution. In that region, there is an NW-trending belt of high-velocity anomaly, probably a buried fault zone. The lower crust below the epicentral region of the Tangshan M _S=7.8 earthquake is a place where the NE-trending belt of low-velocity anomaly meets the NW-trending belt of high-velocity anomaly. The two sets of structures had played an important role in controlling the preparation and occurrence of the M _S=7.8 Tangshan earthquake. Contribution RCEG97006, Research Center of Exploration Geophysics, China Seismological Bureau, China. This project is supported by the Chinese Joint Seismological Science Foundation.  相似文献