芦山地震前后龙门山断裂带南段视应力研究   总被引：1，自引：0，他引：1  

宫悦  龙锋  易桂喜  赵敏  乔慧珍  王宇玺 《震灾防御技术》2013,8(4):389-396

利用四川台网数字地震记录资料,计算了2008年汶川地震之后、2013年芦山地震之前5年内,龙门山断裂带南段ML3.0级以上地震视应力随时间的变化,以及芦山M7.0级地震序列的视应力值及其时空分布特征.结果表明：①从芦山地震之前1年的时间开始,龙门山断裂带南段有视应力的上升过程;②芦山地震余震序列视应力存在几次比较突出的视应力与震级相关性的被打破以及视应力的突降异常,且在震后3个小时之后,视应力即有明显下降的过程;③从归准化的芦山地震序列视应力σapp的空间分布来看,视应力高值区域分布在主震的西南方向和整个余震区东南边缘,并且这两个高视应力区正好分布在该断层面与华南地块紧密接触的边缘;④主震西侧有一片视应力相对较高的区域;⑤主震以北区域的视应力则相对较低.  相似文献   

基于横波射线弹性阻抗的岩性和流体识别研究(英文)     

龚雪萍  张峰  李向阳  陈双全 《应用地球物理》2013,(2):145-156,235

本文推导了关于射线参数的横波(SS)反射系数近似及横波射线弹性阻抗(SREI)表达式。SREI可以写成S-波入射角或者P-波反射角的表达式,分别记作SREIS和SREIP。由井资料计算得到的弹性模型表明SREIP比SREIS及一般的横波弹性阻抗(SEI)具有更强的储层岩性和流体识别能力。Castagna和Smith(1994)收集的25种样本表明大角度SREIP比一般流体因子具有更好的流体识别能力。每个样本包含一组泥岩、含水砂岩和含气砂岩。实际应用也表明,由纵横波阻抗计算得到的大角度SREIP能有效识别致密含气砂岩储层。  相似文献   

Reevaluation of the offset of the Great Wall associated with the ca. M 8.0 Pingluo earthquake of 1739, Yinchuan graben, China     

Aiming Lin  Gang Rao  Jianmin Hu  Wangbin Gong 《Journal of Seismology》2013,17(4):1281-1294

In this study, we reevaluate, based on our investigation, the ground deformation caused around the area of the Great Wall by the ca. M 8 Pingluo earthquake of 1739 along an active fault zone in the Yinchuan graben, on the western margin of the Ordos Block in northern central China. Previous studies have shown that the Great Wall of China was damaged and right-laterally offset by the 1739 M 8 Pingluo earthquake up to ～1.6–2 m, with a 0.1–1.9-m vertical component, at three locations. However, our recent fieldwork and in-situ measurements have shown that the Great Wall was not affected by the ca. M 8 Pingluo earthquake of 1739, as reported previously, but was actually built on preexisting active fault scarps. This study reinterprets the offset of the Great Wall based on these new field observations and attempts to identify the seismogenic source fault that triggered the 1739 Pingluo earthquake. More work is required if we are to better understand the deformation characteristics of the seismogenic source fault and also improve our ongoing assessments of the seismic hazard within the densely populated area of the Yinchuan graben, central China.  相似文献   

Flood frequency under changing climate in the upper Kafue River basin, southern Africa: a large scale hydrological model application   总被引：1，自引：0，他引：1  

Cosmo Ngongondo  Lu Li  Lebing Gong  Chong-Yu Xu  Berhanu F. Alemaw 《Stochastic Environmental Research and Risk Assessment (SERRA)》2013,27(8):1883-1898

The projected impacts of climate change and variability on floods in the southern Africa has not been well studied despite the threat they pose to human life and property. In this study, the potential impacts of climate change on floods in the upper Kafue River basin, a major tributary of the Zambezi River in southern Africa, were investigated. Catchment hydrography was delineated using the Hydro1k at a spatial resolution of 1 km. The daily global hydrological model WASMOD-D model was calibrated and validated during 1971–1986 and 1987–2001 with the simple-split sample test and during 1971–1980 and 1981–1990 with the differential split sample test, against observed discharge at Machiya gauging station. Predicted discharge for 2021–2050 and 2071–2100 were obtained by forcing the calibrated WASMOD-D with outputs from three GCMs (ECHAM, CMCC3 and IPSL) under the IPCC’s SRES A2 and B1 scenarios. The three GCMs derived daily discharges were combined by assigning a weight to each of them according to their skills to reproduce the daily discharge. The two calibration and validation tests suggested that model performance based on evaluation criteria including the Nash–Sutcliffe coefficient, Pearson’s correlation coefficient (r), Percent Bias and R ² was satisfactory. Flood frequency analysis for the reference period (1960–1990) and two future time slices and climate change scenarios was performed using the peak over threshold analysis. The magnitude of flood peaks was shown to follow generalised Pareto distribution. The simulated floods in the scenario periods showed considerable departures from the reference period. In general, flood events increased during both scenario periods with 2021–2050 showing larger change. The approach in our study has a strong potential for similar assessments in other data scarce regions.  相似文献   

底栖有孔虫壳貌微观特征对海域低氧及酸化环境指示的研究进展     

王飞飞  于志刚  刘健  许博超  宫少军 《海洋学报》2018,40(5):1-14

受人类活动和全球变化的影响，河口和近海海域的低氧以及酸化等环境问题日益突出，近年来已成为科学研究的热点问题并受到社会广泛关注。本文通过梳理底栖有孔虫壳貌微观特征对海域低氧及酸化环境指示的研究现状，总结了壳体特征（壳径和壳重）、壳孔特征（密度、孔径、形态）、壳饰（牙突、瘤状物、脐翼）、壳面溶蚀及壳体重新钙化所引起的房室畸变等指标应用的理论基础和方法技术，并分析了影响结果的各种干扰因素，指出了在研究中若干需要注意的问题和研究方向，提出了一些具有可操作性的建议，为更好地将其应用于近岸海域低氧和酸化环境的研究中并推进至地质历史时期此类古环境的演化研究提供参考。  相似文献   

An iterative approach based on contextual information for matching multi‐scale polygonal object datasets     

Lingjia Liu  Xiaohui Ding  Xinyan Zhu  Liang Fan  Jun Gong 《Transactions in GIS》2020,24(4):1047-1072

Object matching facilitates spatial data integration, updating, evaluation, and management. However, data to be matched often originate from different sources and present problems with regard to positional discrepancies and different levels of detail. To resolve these problems, this article designs an iterative matching framework that effectively combines the advantages of the contextual information and an artificial neural network. The proposed method can correctly aggregate one‐to‐many (1:N) and many‐to‐many (M:N) potential matching pairs using contextual information in the presence of positional discrepancies and a high spatial distribution density. This method iteratively detects new landmark pairs (matched pairs), based on the prior landmark pairs as references, until all landmark pairs are obtained. Our approach has been experimentally validated using two topographic datasets at 1:50 and 1:10k. It outperformed a method based on a back‐propagation neural network. The precision increased by 4.5% and the recall increased by 21.6%, respectively.  相似文献   

网购时代广州市居民购买食品行为特征     

邓清华  薛德升  龚建周 《热带地理》2019,39(5):780-789

基于广州市居民食品购物行为问卷调查数据,利用交叉频数、卡方检验和对应分析,通过网购食品者同不网购食品者、不同区位网购食品者、不同网购食品频率者的对比,分析了网络购物影响下广州市居民购买食品行为的一般特征和空间特征。结果发现：1）网络购买食品的接受度总体不高,传统实体购物模式仍占主导,网络购买食品对实体店购买食品有一定的替代效应。2）网络购买食品对居住地周边商店负面影响较大,对商业区影响很小,超市和百货公司休闲零食、地方特产类食品销售会受到一定负面影响,生鲜类商店所受影响较小。3）不同区位居民网购食品的频率差异较小,单次花费、时间和网购原因空间差异较大,实体购物条件差的居民更倾向于网络购买食品,验证了Anderson等提出的“效率假说”。4）网购食品者的实体购物出行目的休闲性增加,周末购物出行更频繁,网购食品频率高的居民购物出行时间更短。  相似文献   

Wave Dissipation Characteristics of A Mountain-Type Breakwater     

Gong  Ye-jun  Zhan  Jie-min  Hu  Wen-qing  Fan  Qing  Cai  Wen-hao 《中国海洋工程》2020,34(6):863-870

China Ocean Engineering - One mountain-type breakwater consisting of two inclined plates and one vertical plate is proposed based on several types of traditional free surface breakwaters, including...  相似文献   

Experimental Research on A New Type of Floating Breakwater for Wave-Absorbing and Energy-Capturing     

Huang  Fang-ping  Gong  Kai  Liu  Zuo-shi  Chen  Jun-hua  Huang  Yan-chen 《中国海洋工程》2020,34(6):817-827

China Ocean Engineering - To avoid the damage caused by big wind and wave in cage culture, and to solve the problem of energy supply faced by automatic breeding equipment, a new type of floating...  相似文献   

Model for large strain consolidation with non-Darcian flow described by a flow exponent and threshold gradient     

Xu-Dong Zhao  Wen-Hui Gong 《国际地质力学数值与分析法杂志》2019,43(14):2251-2269

Many pieces of evidence have confirmed that the seepage in fine-grained soils can deviate from traditional Darcy's law that contributes to the consolidation theory. In this paper, a numerical model, referred to as consolidation with non-Darcian flow 2 (CNDF2), is developed for the 1D large strain consolidation of a saturated porous medium with the non-Darcian flow. The algorithm accounts for vertical strain, general constitutive relationships, the relative velocity of the fluid and solid phases, variable compressibility and permeability relation during consolidation, time-dependent loading, and unload/reload effects. Compared with the CS2 model proposed in previous studies, some parts of the CNDF2 model are modified in order to adapt to the non-Darcian flow, especially the equivalent series hydraulic conductivity and fluid flow. The verification examples of the CNDF2 model demonstrate excellent accuracy for both small strain and large strain consolidation. According to the applicable conditions of non-Darcian flow law, the CNDF2 model is most suitable for the fine-grained soil. The development of CNDF2 is first presented, followed by examples to analyze the influences of the non-Darcian flow on the consolidation behavior.  相似文献