Dynamic Response to Seismic Waves at the Shallow Slope Supported by Bolts     

Jun Wang  Jie Liu  Qiao Liang  Xiangsen Ouyang 《Geotechnical and Geological Engineering》2018,36(4):1991-2001

In the soil slope supported by bolts, longitude waves instead of transverse waves, generated by earthquakes, first reach the slope surface. With the dynamic response of the P (pressure) wave along the anchorage structure, first, a theoretical study was conducted to investigate the propagation characteristics of the interference superposition, generated by the SV (shear-vertical) and the P waves. The SV wave was formed by the wave, originating from the bottom and reflected from the free surface of the slope, whereas the latter was the incident P wave, propagating in the slope. In addition, the structural measures, restraining the seismic wave, and the characteristics of the restraint effect at the free segment of the bolt were investigated. According to the wave-way difference between the incident P wave and the reflected SV wave, the minimum critical slope angle, influenced by the interference at the shallow slope, and the maximum influencing depth of the dynamic response, acting vertically to the slope surface, were obtained. The results indicate that the maximum influencing depth linearly correlated with the slope angle. Furthermore, based on the propagation characteristics of the P wave along the bolt, and the coupled relation between the wave length and the anchorage design parameters, the axial acceleration of the wave propagating along the bolt axis was obtained. Then, the theoretical length of the anti-seismic bolt, subjected to seismic waves, and the compensation force of the anchorage structure were obtained. Finally, a numerical study, based on FlAC3D, properly verified the theoretical conclusions.  相似文献   

A noise suppression method for superconducting full tensor aeromagnetic gradient measurement data     

ZiQi Guo  ShuangXi Ji  Yanchao Qiao  Ji Wang 《《地质学报》英文版》2018,92(Z1):367-368

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陕西宁强胡家坝地区震旦系灯影组风暴沉积特征     

刘明博  林晋炎  高硒  王晓伟  华洪  徐乔 《城市地质》2018,(2):57-63

陕西宁强胡家坝地区新元古界震旦系灯影组出露较好,为一套碳酸盐岩和碎屑岩组合,岩性组合可划分为3段:藻白云岩段、高家山段和碑湾段,其中高家山段风暴沉积发育,为本文研究重点。风暴沉积构造特征在高家山剖面和狮子崖剖面各不相同,高家山剖面丘状交错层理发育,为风暴沉积典型特征;狮子崖剖面碎屑岩沉积可见底面构造、粒序层、水平层理现象等,灰岩层发育水平层理。通过野外实测、室内薄片鉴定等,认为高家山剖面高家山段中部化石层位为海水较浅的近源风暴沉积,而狮子崖相应层位为相对海水较深的远源风暴沉积。  相似文献   

Qualitative spatial reasoning on topological relations by combining the semantic web and constraint satisfaction     

Yandong Wang  Mengling Qiao  Hui Liu  Xinyue Ye 《地球空间信息科学学报》2018,21(2):80-92

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Beidou satellite maneuver thrust force estimation for precise orbit determination     

Jing Qiao  Wu Chen 《GPS Solutions》2018,22(2):42

Beidou satellites, especially geostationary earth orbit (GEO) and inclined geosynchronous orbit (IGSO) satellites, need to be frequently maneuvered to keep them in position due to various perturbations. The satellite ephemerides are not available during such maneuver periods. Precise estimation of thrust forces acting on satellites would provide continuous ephemerides during maneuver periods and could significantly improve orbit accuracy immediately after the maneuver. This would increase satellite usability for both real-time and post-processing applications. Using 1 year of observations from the Multi-GNSS Experiment network (MGEX), we estimate the precise maneuver periods for all Beidou satellites and the thrust forces. On average, GEO and IGSO satellites in the Beidou constellation are maneuvered 12 and 2 times, respectively, each year. For GEO satellites, the maneuvers are mainly in-plane, while out-of-plane maneuvers are observed for IGSO satellites and a small number of GEO satellites. In most cases, the Beidou satellite maneuver periods last 15–25 min, but can be as much as 2 h for the few out-of-plane maneuvers of GEO satellites. The thrust forces acting on Beidou satellites are normally in the order of 0.1–0.7 mm/s². This can cause changes in velocity of GEO/IGSO satellites in the order of several decimeters per second. In the extreme cases of GEO out-of-plane maneuvers, very large cross-track velocity changes are observed, namely 28 m/s, induced by 5.4 mm/s² thrust forces. Also, we demonstrate that by applying the estimated thrust forces in orbit integration, the orbit errors can be estimated at decimeter level in along- and cross-track directions during normal maneuver periods, and 1–2 m in all the orbital directions for the enormous GEO out-of-plane maneuver.  相似文献   

滇西北石鼓杂岩中花岗质片麻岩年代学、地球化学特征及地质意义     

罗改  张彤  贾小川  杨学俊  肖典  谭晓莲 《地质学报》2021,95(11):3335-3351

青藏高原东南缘滇西北前寒武纪石鼓变质杂岩中新识别出一套花岗质片麻岩.采用LA-ICP-MS方法进行锆石U-Pb年代学分析,获得206Pb/238 U加权平均年龄分别为790±11 Ma(MSWD=2.1,n=10)和814±15 Ma(MSWD=5.7,n=9),显示其形成于新元古代早期.地球化学特征显示,岩石具有高硅(SiO2=66.05％～77.16％)、高 K2O/Na2O(0.90～9.26,均值2.57)特征,MgO=0.35％～3.60％,TFeO=1.02％～4.86％,P2O5=0.03％～0.17％.铝饱和指数A/CNK为1.08～2.51,矿物组合中出现石榴子石和白云母等富铝矿物,CIPW标准矿物中刚玉分子平均含量为4.72％,显示为强过铝质花岗岩.球粒陨石标准化稀土配分显示轻稀土元素富集,(La/Yb)N=1.79～12.34,具明显的Eu负异常(δEu=0.21～0.67).原始地幔标准化蛛网图显示,岩石富集Rb、U,明显亏损Ba、Ta、Nb、Sr、P、Ti元素.综合分析认为,花岗质片麻岩原岩主要为低成熟度、黏土贫乏的砂质岩在高温条件下部分熔融的产物,形成于后碰撞构造环境,是Rodinia超大陆汇聚事件在滇西北石鼓地区的响应.  相似文献   

Geomorphic natural hazard on loess terrain: expansion on the gully sidewall     

Ma  Yulei  Xu  Xiangzhou  Xiao  Peiqing  Yan  Qiao  Zhao  Chao 《Natural Hazards》2021,109(3):2535-2555

Natural Hazards - Gully sidewall expansion is an important geomorphic natural hazard, and the expansion destroys a large extent of agricultural land in the loess regions every year. The main aim of...  相似文献   

四川省大地构造单元划分及其基本特征          下载免费PDF全文

罗改  王全伟  秦宇龙  曾宜君  李云泉  杨学俊  李有波 《沉积与特提斯地质》2021,41(4):633-647

四川省大地构造演化研究已有百余年的历史,不同时期、不同学派在不同的尺度上提出了不同的大地构造单元划分方案,其中仍存在诸多争议。本文结合近30年来四川省特别是造山带地区开展的蛇绿岩和洋板块地层等调查和研究成果,以李廷栋所提出的洋板块地质学理念为指导思想,以区域主构造事件形成的优势大地构造相的时空结构组合和存在状态为基本原则,划分出秦-祁-昆造山系、勉县-略阳对接带、北羌塘-三江造山系以及扬子克拉通4个一级构造单元,包括11个二级构造单元和24个三级构造单元。  相似文献   

Cretaceous paleogeomorphology restoration and its controlling mechanism on sand-bodies in Chunguang exploration area,Junggar Basin          下载免费PDF全文

Cheng Yi-Fan  Dong Yan-Lei  Zhu Xiao-Min  Yang Dao-Qing  Wu Wei  Yang Ke  Su Bin  Zhao Rui-Xing  Qiao Chen-Kai 《古地理学报》2021,22(6):1127-1142

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基于欧拉反褶积法的无人机航磁找矿应用     

乔中坤  马国庆  于平  周文纳  张志厚  焦健  周帅  孟兆海  唐水亮 《吉林大学学报(地球科学版)》2021,51(2):552-560

无人机航磁测量以其高效、安全、低成本等优点逐渐应用到中小面积大比例尺资源勘探领域。本文针对安徽芜湖市三山区22 km²区域构造刻画和找矿前景预测,开展1∶20 000高精度无人机航磁测量工作;推导了欧拉反演求解过程,并分析对比构造指数选取,使用构造指数为0的欧拉反褶积对航磁数据进行反演求解,获得地下磁异常体构造边界解集信息;将其应用到研究区域航磁数据反演,根据反演得到的边界位置和深度信息圈定了18处断裂,并结合异常特征给出了8.7 km²岩浆岩分布区,根据宁芜区域铁矿成矿特点,圈定岩浆分布区及边界为成矿详查区。  相似文献