土非线性参数变异性对标准设计谱的影响     

李波  袁晓铭  孙锐 《世界地震工程》2010,(Z1)

岩土工程中存在许多不确定性,建筑物抗震规范设计中的标准设计谱实际代表着一种平均结果,并没有考虑到场地土体非线性参数的变异性。文中采用数值模拟的方法研究了土非线性参数变异性对标准设计谱的影响。给出了考虑土非线性参数变异性的概率设计谱。结果表明,土非线性参数变异性对标准设计谱的影响显著;粘性土和无粘性土的动剪切模量比对标准设计谱的影响决定于土非线性参数的概率水准,同时也取决于概率设计谱的频段;烈度7度、8度和9度下土体动剪切模量比变异性使标准设计谱平台最大变化50%、80%和100%,阻尼比变异性使标准设计谱平台最大变化40%、45%和60%。  相似文献   

吉林夹皮沟金矿带黄铁矿热电性及热爆裂特征   总被引：4，自引：2，他引：2  

张玙  袁万明  王庆飞  刘向伟  马楠  赵凯 《现代地质》2010,24(5):870-879

通过对夹皮沟金矿带主要载金矿物黄铁矿的热电性和热爆裂特征分析,确定了主成矿世代及各世代矿化类型,预测了深部探矿的可能性。黄铁矿以电子型(N型)为主,极少有空穴型(P型),N型热电系数分布于-347.3～-6.2 μV·℃-1,P型热电系数介于17.4～193.5 μV·℃-1, 成矿温度集中于258.8～319.2 ℃, 剥蚀率为50.260%～50.485%。爆裂曲线反映中低温(＜280 ℃)矿化没有高温(＞290 ℃)矿化好。综合分析认为,夹皮沟金矿带矿化分早期高温世代(热电系数峰值为-120 μV·℃-1,成矿温度峰值为320 ℃)和晚期中低温世代(热电系数值峰值为-210 μV·℃-1,成矿温度峰值为270 ℃)。前者包括石英脉型与蚀变岩型,在矿体走向与夹皮沟主断裂一致及相交的矿区中均有发育;后者属石英脉型,主要在矿体走向与夹皮沟主断裂相交的矿区发育,叠加于高温世代热液矿化之上。高温热液矿化世代是主成矿世代,但有叠加的部位矿化增强。  相似文献   

THE TECTONIC ACTIVITY CHARACTERISTICS OF AWANCANG FAULT IN THE LATE QUATERNARY,THE SUB-STRAND OF THE EASTERN KUNLUN FAULT          下载免费PDF全文

LI Chen-xia  YUAN Dao-yang  YANG Hu  XU Xi-wei 《地震地质》2016,38(1):44-64

It is well known that the slip rate of Kunlun Fault descends at the east segment, but little known about the Awancang Fault and its role in strain partitioning with Kunlun Fault. Whether the sub-strand(Awancang Fault) can rupture simultaneously with Kunlun Fault remains unknown. Based on field investigations, aerial-photo morphological analysis, topographic surveys and ¹⁴C dating of alluvial surfaces, we used displaced terrace risers to estimate geological slip rates along the Awancang Fault, which lies on the western margin of the Ruoergai Basin and the eastern edge of the Tibetan plateau, the results indicate that the slip rate is 3mm/a in the middle Holocene, similar to the reduced value of the Kunlun Fault. The fault consists of two segments with strike N50° W, located at distance about 16km, and converged to single stand to the SE direction. Our results demonstrate that the Awancang fault zone is predominantly left-lateral with a small amount of northeast-verging thrust component. The slip rates decrease sharply about 4mm/a from west to east between the intersection zone of the Awancang Fault and Kunlun Fault. Together with our previous trenching results on the Kunlun Fault, the comparison with slip rates at the Kunlun fault zone suggests that the Awancang fault zone has an important role in strain partitioning for east extension of Kunlun Fault in eastern Tibet. At the same time, the 15km long surface rupture zone of the southeast segment was found at the Awancang Fault. By dating the latest faulted geomorphologic surface, the last event may be since the 1766±54 Cal a BP. Through analysis of the trench, there are four paleoearthquake events identified recurring in situ on the Awancang Fault and the latest event is since (850±30)a BP. The slip rate of the Awancang Fault is almost equivalent to the descending value of the eastern part of the east Kunlun Fault, which can well explain the slip rate decreasing of the eastern part of the east Kunlun Fault(the Maqin-Maqu segment)and the characteristics of the structure dynamics of the eastern edge of the Tibet Plateau. The falling slip rate gradient of the eastern Kunlun Fault corresponds to the geometric characteristic. It is the Awancang Fault, the strand of the East Kunlun Fault that accommodates the strain distribution of the eastward extension of the east Kunlun Fault. This study is helpful to seismic hazard assessment and understanding the deformation mechanism in eastern Tibet.  相似文献   

兰州地区剪切波速实测误差分析与评价          下载免费PDF全文

陈卓识  董林  袁晓铭 《地震工程学报》2016,38(5):757-769

为了给兰州乃至西北地区的地震安全性评价和重大工程抗震设计提供参考,在兰州地区选取4个不同类别场地,完成由10家单位参加、使用不同仪器剪切波速现场测试误差专项实验,研究该地区剪切波速实测误差分布规律,讨论测试误差对地表加速度反应谱影响的统计特征,并给出该地区剪切波速测试误差评价。结果表明:兰州地区各单位剪切波速测试误差具有明显规律性,测试误差绝大部分符合标准正态分布,且误差大小不随深度和场地类别而改变;兰州地区波速测试水平优于全国平均水平,Ⅰ类、Ⅱ类和Ⅲ类场地的剪切波速测试精度较高,偏差较小,其平均标准差可以定为10%;就兰州地区而言,其1倍波速测试标准差引起PGA最大偏差为25%,2倍标准差为50%;给定波速测试误差下反应谱变化程度与输入波形相关,输入波频率成分与场地频率成分接近的地震输入下,误差影响较大,反之则影响较小。  相似文献   

GEOMORPHIC FEATURES OF THE SHULE RIVER DRAINAGE BASIN IN QILIANSHAN AND ITS INSIGHT INTO TECTONIC IMPLICATIONS          下载免费PDF全文

SU Qi  YUAN Dao-yang  XIE Hong  SHAO Yan-xiu  LIANG Ming-jian. Lanzhou Institute of Seismology  China Earthquake Administration  Lanzhou  China  . Lanzhou National Observatory of Geophysic 《地震地质》2016,38(2):240-258

Because of the strong uplift of the Qilian Shan since late Cenozoic,the drainage basins that are derived from the mountains have undergone strong tectonic deformation.So the typical geomorphology characteristics of these drainage basins may indicate the strong tectonic movement in the region.For example,the Shule River drainage basin,which originates from the western part of the Qilian Shan owns unique geomorphology characteristics which may indicate the neotectonic movement. Stream networks of the Shule drainage basin extracted from the DEM data based on GIS spatial analysis technology are graded into five levels using Strahler classification method.Four sub-catchments,numbered 1,2,3 and 4 are chosen for detailed analysis.Furthermore,the four sub-catchments,the hypsometric integral curves,Hack profiles,SL index and average slope of the Shule drainage basin are determined by GIS tools.In addition,we analyzed the slope spectrum of the Shule drainage basin. The average elevation of the Shule drainage basin is very high,however,the slope of the drainage basin is very low,the gentle slope occupies so large area proportion that the slope spectrum shows a unimodal pattern and a peak value is in low slope region (0°~5°),so tectonic movement has a strong influence on the drainage basin.Under the intensive impact of the tectonic movement of the active fault and regional uplift,the hypsometric integral curve is sigmoid,revealing that the Shule drainage basin is in the mature stage.The Hack profile is on a convex,the longitudinal profile is best fitted by linear fitting and the abnormal data of the SL index of the Shule River has a good fit with the section through which the active fault traverses,that means the tectonic movement of the active fault has strong influence on the river's SL index.It is worth noting that lithologic factors also have great impact on the river geomorphology in some sections. According to the above analysis,we recognize that in the interior of active orogen,the evolution of river geomorphology usually is influenced by tectonic movement and reveals the regional neotectonics in turn.  相似文献   

GEOMORPHIC FEATURES OF THE HEIHE RIVER DRAINAGE BASIN IN WESTERN QILIAN SHAN-HEXI CORRIDOR AND ITS TECTONIC IMPLICATIONS          下载免费PDF全文

SU Qi  YUAN Dao-yang  XIE Hong 《地震地质》2016,38(3):560-581

Using quantitative geomorphic factors for regional active tectonic evolution is becoming more and more popular. Qilian Mountains-Hexi Corridor which locates in the northern edge of Qinghai-Tibet plateau is the most leading edge of the plateau's northward extension. The uplift rate of all segments and the intensity of influence from tectonic activity are the important evidences to understand the uplift and extension of the plateau. Heihe River Basin is located at the northern piedmont of the western segment of Qilian Mountains, the development of the rivers is influenced by the tectonic activity of the Qilian Mountains, and the unique river morphology is important carriers of the regional tectonic uplift. Geomorphologic indexes such as hypsometric integral, geomorphologic comentropy and river longitudinal profiles were extracted by GIS tools with free access to the Shuttle Radar Topography Mission(SRTM)DEMs, and according to the different expression of the geomorphological indexes in the Heihe River Basin, we divided the drainage basin into two parts and further compared them to each other. Recent studies reveal that obvious differences exist in the landscape factors(hypsometric integral, geomorphology entropy and river profiles)in the east and west part of the Heihe Basin. The structural intensity of the west part is stronger than that of the east, for example, in areas above the main planation surface on the western part, the average HI value is 0.337 8, and on the eastern part the HI value is 0.355. Accordingly, areas under the main planation surface are just on the contrary, indicating different structural strength on both sides. Similar phenomenon exists in the whole drainage basins. Furthermore, by comparing the fitting river profiles with the real river profiles, differential uplift is derived, which indicates a difference between west and east(with 754m on the western part and 219m on the east). Comprehensive comparison and analysis show that the lithologic factors and precipitation conditions are less influencing on the geomorphic factors of the study area, and the tectonic activities, indicated by field investigation and GPS inversion, are the most important element for geomorphic evolution and development. The variation of the geomorphologic indexes indicates different tectonic strength derived from regional structures of the Qilian Shan.  相似文献   

高强防寒保温泡沫混凝土研制与工程应用   总被引：1，自引：1，他引：0  

袁克阔 《冰川冻土》2016,38(2):438-444

复杂地层寒区隧道填充材料需兼具防寒保温、抗震和优化支护等性能,为解决常规泡沫混凝土在复杂地层寒区隧道应用中存在的不足,通过正交试验得到了自制泡沫混凝土的最佳配合比,研制了一种高强防寒保温泡沫混凝土.通过室内试验,研究了所制泡沫混凝土的保温性能和冻融劣化特征,并采用数值分析方法探讨了西藏嘎隆拉隧道初衬和二衬之间加设泡沫混凝土垫层后的温度场变化规律.结果表明：该泡沫混凝土具有较好的保温性能和抗冻融损伤性能,同时强度、延性较普通泡沫混凝土都有明显改善.数值计算结果显示,当在初衬和二衬之间增设泡沫混凝土垫层时,其相应位置的温度变幅由不设置时的4.5℃变为2℃,最低温度由1℃提高到了3℃,表明加设所研制泡沫混凝土垫层对于阻止围岩受到隧道内冷空气的侵害具有非常显著的效果.  相似文献   

两种pH水环境干、湿循环作用对泥质砂岩的侵蚀研究     

王子娟  刘新荣  傅晏  张梁  袁文 《岩土力学》2016,37(11):3231-3239

选取三峡库区某边坡的泥质砂岩为研究对象,分别对pH=3和pH=7溶液下干、湿循环作用的泥质砂岩进行电镜扫描试验（SEM）、4种围压下的三轴压缩试验,通过MATLAB软件处理得到不同pH值和干、湿循环次数下SEM图像的骨架面积比和分形维数。研究表明：在相同的干、湿循环次数下,pH=3酸性环境下的分形维数比pH=7的要大;分形维数与吸水率成正比例相关;与骨架面积、凝聚力成反比例相关;泥质砂岩在干、湿循环作用下的临界骨架面积比为0.55左右;提出了泥质砂岩在干、湿循环作用下的侵蚀度概念,计算并拟合了泥质砂岩的侵蚀度随干、湿循环次数变化的关系曲线;推导出凝聚力的损伤变量公式,为研究不同pH水环境对岩石的侵蚀作用提供参考依据。  相似文献   

重塑黄土压缩变形的预测模型研究     

石博溢  倪万魁  王衍汇  李征征  袁志辉 《岩土力学》2016,37(7):1963-1968

针对黄土填方场地的沉降变形问题,通过进行不同初始含水率和干密度的重塑黄土的高压固结试验,发现荷载与干密度的比值（p/?d）与荷载（p）呈很好的线性关系,并以此为依据建立了不同厚度（荷载）填方场地的沉降预测模型。该模型有k和b两个参数,其中k随着初始含水率（w0）或初始干密度（?d0）的增大而减小,三者之间的关系为：?d0k +w0 =1;b主要与初始干密度有关,随着初始干密度增大而减小。与前人基于孔隙比和荷载关系所建立的压缩变形计算模型的对比分析发现,用干密度和荷载表示土压缩性的方法与试验数据拟合精度更高,且线性相关性更强,更适合于重塑黄土的压缩变形预测。  相似文献   

掺砾黏土拉伸断裂细观特性研究     

袁会娜  张骏  张其光 《岩土力学》2016,37(11):3096-3104

掺砾黏土在高心墙堆石坝工程中的应用越来越广泛,其拉伸断裂特性对心墙的安全至关重要。将掺砾黏土视作四相复合材料,基于图像处理和随机投放建立了考虑真实砾石形态的细观数值模型,结合物理试验的结果验证了其有效性,并分析了掺砾黏土拉伸断裂的宏细观特性。应力位移曲线的宏观非线性是细观非均质性的体现,砾石的掺入大幅减低了抗拉强度,但提高了峰后抗拉性能;土石界面是微裂缝发展的源头,拉伸断裂是一个微裂缝萌生、扩展以至汇集形成宏观裂缝的过程;拉伸断裂发生在一个区域,即断裂过程区,该区域的形成与砾石的随机分布有关。最后,采用数值试验分析了随机砾石投放和掺砾量对掺砾黏土宏细观力学行为的影响。  相似文献