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971.
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975.
In stability analysis of rock blocks, the deformability of the blocks can conveniently be simulated using the boundary element method (BEM). However, all boundary conditions are given as stresses. Thus, the displacement solution is not unique. In this paper, an algorithm is proposed to remove rigid body motions in the solution of the boundary form of Somigliana identity discretized by the direct BEM formulation. The algorithm is applied to the calculation of the normal stiffness of rock blocks and coupled with BS3D, large displacement and rotation algorithm for the general stability of rock blocks. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
976.
印支地块思茅地区早白垩世古地磁结果及其构造意义 总被引:2,自引:0,他引:2
对印支地块思茅地区的早白垩世红层开展详细的岩石磁学和古地磁学研究,获得镇沅剖面特征剩磁方向Ds=52.4°,Is=45.5°,κ=77.9,α95=6.3°;普洱剖面特征剩磁方向Ds=46.2°,Is=46.6°,κ=50.9,α95=5.6°;江城剖面特征剩磁方向Ds=8.6°,Is=42.2°,κ=117.1,α95=4.0°。对普洱和江城剖面进行E-I磁倾角偏低检验,结果显示江城剖面不存在磁倾角偏低,普洱剖面由于偏角较分散,导致其伸展方向出现假象,推测的磁倾角偏大,出现实测磁倾角偏低的假象。思茅地区各采样剖面之间的磁偏角差异表明,块体内部发生过差异性旋转变形,其变形的过程不仅受控于边界深大断裂,也与内部小断裂的活动有密切关系。若进一步考虑华南地块白垩纪可能存在的磁倾角偏低现象,则该结果说明印度支那地块思茅地区白垩纪以来相对于华南地块向南滑移量为570±310km,接近构造地质研究推测的红河大断裂左行滑移量。 相似文献
977.
Multi‐scale Decomposition of Co‐seismic Deformation from High Resolution DEMs: a Case Study of the 2004 Mid‐Niigata Earthquake 总被引:1,自引:0,他引:1
Decomposing co-seismic deformation is an immediate need for researchers who are interested in earthquake inversion analysis and geo-hazard mapping. However, conventional InSAR or digital elevation models (DEMs) imagery analyses only provide the displacement in the Line-of-Sight (LOS) direction or elevation changes. The 2004 Mid-Niigata earthquake in Japan provides lessons on how to decompose co-seismic deformation from two sets of DEMs. If three adjacent points undergo a rigid-body-translation movement, their co-seismic deformation can be decomposed by solving simultaneous equations. Although this method has been successfully used to discuss tectonic deformations, the algorithm needed improvement and a more rigorous algorithm, including a new definition of nominal plane, DEMs comparability improvement and matrix condition check is provided. Even with these procedures, the obtained decomposed displacement often showed remarkable scatter prompting the use of the moving average method, which was used to determine both tectonic and localized displacement characteristics. A cut-off window and a pair of band-pass windows were selected according to the regional geology and construction activities to ease the tectonic and localized displacement calculations, respectively. The displacement field of the tectonic scale shows two major clusters of large lateral components, and coincidently major visible landslides were found mostly within them. The localized displacement helps to reveal hidden landslides in the target area. As far as the Kizawa hamlet is concerned, the obtained vectors show down-slope movements, which are consistent with the observed traces of dislocations that were found in the Kizawa tunnel and irrigation wells. The method proposed has great potential to be applied to understanding post-earthquake rehabilitation in other areas. 相似文献
978.
QU Chunyan SHAN Xinjian LIU Yunhu ZHANG Guohong SONG Xiaogang ZHANG Guifang GUO Liming HAN Yufei 《《地质学报》英文版》2012,86(2):510-519
The 12 May 2008 Wenchuan Ms8.0 earthquake produced surface displacements along the causative fault, the Yingxiu–Beichuan Fault, which are up to several meters near the fault. Because of the large gradient, satellite synthetic aperture radar (SAR) interferometric data are strongly incoherent; the usual SAR interferometry method does not allow such displacements to be measured. In the present study, we employed another approach, the technique based on pixel offset tracking, to solve this problem. The used image data of six tracks are from the Advanced Land Observing Satellite, Phased Array type L-band Synthetic Aperture Radar (ALOS/ PALSAR) dataset of Japan. The results show that the entire surface rupture belt is 238 km long, extending almost linearly in a direction of 42° north–east. It is offset left laterally by a north–west-striking fault at Xiaoyudong, and turns at Gaochuan, where the rupture belt shifts toward the south by 5 km, largely keeping the original trend. In terms of the features of the rupture traces, the rupture belt can be divided into five sections and three types. Among them, the Beichuan–Chaping and Hongkou–Yingxiu sections are relatively complex, with large widths and variable traces along the trend. The Pingtong–Nanba and Qingping–Jingtang sections appear uniform, characterized by straight traces and small widths. West of Yingxiu, the rupture traces are not clear. North of the rupture belt, surface displacements are 2.95 m on average, mostly 2–3.5 m, with 7–9 m the maximum near Beichuan. South of the rupture belt, the average displacement is 1.75 m, dominated by 1–2 m, with 3–4 m at a few sites. In the north, the displacements in the radar line of sight are of subsidence, and in the south, they are uplifted, in accordance with a right-slip motion that moves the northern wall of the fault to the east, and the southern wall to the west, respectively. Along the Guanxian–Jiangyou Fault, there is a uplift zone in the radar line of sight, which is 66 km long, 1.5–6 km wide, and has vertical displacements of approximately 2 m, but no observable rupture traces. 相似文献
979.
青东凹陷东边界为郯庐断裂带在渤海海域内西支断裂所在,平面上由4条北北东向断裂呈左阶雁列式排列,剖面上以上盘下降为主,局部具有张扭性和压扭性花状构造现象。青东凹陷东界上的郯庐断裂新生代经历了古近纪右行平移正断层活动、古近纪末盆地挤压反转中的逆右行平移、新近纪的弱拉张活动和第四纪以来的逆右行平移4个演化阶段。古近纪断陷期,先存的郯庐断裂带由于具有较低的强度,在南北向伸展应力场作用下复活并表现为具有右行平移分量的斜向拉张活动,在浅部新生4条左阶雁列式断层,并与盆地内北西向基底断裂系统和东西向新生正断层共同控制了古近系的沉积格局。古近纪末发生了盆地反转,结束了断陷盆地发育阶段,在北东东-南西西向区域挤压应力作用下郯庐断裂表现为逆右行平移活动。新近纪坳陷阶段,盆地内构造活动较弱,主要受控于岩石圈热沉降作用,但郯庐断裂仍具有较弱的伸展活动。第四纪以来,郯庐断裂再次转变为逆右行平移活动。 相似文献
980.
基于强度折减法的三维边坡失稳判据 总被引:1,自引:0,他引:1
为了寻求基于强度折减法的三维边坡稳定分析的合理判据,依托珍珠坝边坡采用FALC3D对位移突变判据及塑性区贯通判据进行分析,并与ANSYS计算结果和二维极限平衡结果进行比较。结果表明:在采用强度折减法对三维边坡稳定分析时,位移突变判据根据总位移增量和折减系数关系曲线较易识别突变点且特征点选在边坡坡顶滑体上较为合理;针对塑性区贯通判据的不足,提出了以贯通率增量和折减系数曲线上的突变点来判别边坡稳定性。因此,三维边坡失稳判据的合理选用应遵循以下原则:建议在滑带明确的情况下采用塑性区贯通率增量突变判据,在滑带未知的情况下采用位移增量突变判据。 相似文献