粗粒料动三轴试验颗粒流模拟对称性研究     

杨贵  刘汉龙  任青文 《世界地震工程》2010,(Z1)

以粗粒料动三轴数值模拟为例,分析了不同对称模型(1/2,1/4,1/8,1/12)条件下,粗粒料动剪切模量和阻尼比的变化规律。计算结果表明,不同对称模型的计算结果存在一定的差异,但其变化规律基本一致,随着模型对称比例的增大动剪切模量逐渐增大,阻尼比逐渐减小,计算时间成倍减少。分析了颗粒生成过程中不均匀性对试验结果的影响。计算结果表明:1/8模型动剪切模量和阻尼比影响较小;1/12模型动剪切模量影响较大,阻尼比影响较小。建议在动力分析过程中采用1/8模型即可。  相似文献   

EXPERIMENTAL STUDY OF TEMPERATURE EVOLUTION AND IDENTIFICATION OF INSTABILITY POSITION OF PLANAR STRIKE-SLIP FAULT DURING PROCESS OF STICK-SLIP          下载免费PDF全文

REN Ya-qiong  MA Jin  LIU Pei-xun  CHEN Shun-yun 《地震地质》2016,38(1):65-76

Stick-slip of fault in laboratory accompanies change of temperature. Temperature change is not only concerned with sliding friction, but also with the stress state of the sample. In this article, we use infra-red thermal imaging system as wide-range observation means to study the temperature variation of different stages during the deformation of sample. The rock sample for the experiment is made of granodiorite from Fangshan County with a size of 300mm×300mm×50mm. It is cut obliquely at an angle of 45°, forming a planar fault. Two-direction servo-control system was used to apply load on the sample. The load in both directions was forced to 5MPa and maintained constant (5MPa) in the X direction, then the load in the Y direction was applied by a displacement rate of 0.5μm/s, 0.1μm/s and 0.05μm/s successively. The left and below lateral of the sample were fixed, and the right and top lateral of the sample were slidable when loaded. The experiment results show not only the temperature change from increase to decrease caused by conversion of stress accumulation to relaxation before and after the peak stress, but also opposite variation of temperature increase on fault and temperature decrease in rock during instability stage. Most important of all, we have found the temperature precursor identifying the position of instability through the temperature variation with time along the fault. It shows that rate of temperature increase of instability position keeps relative high value since the stage of strongly off-linear stage, and accelerates in stage of meta-instability. After separating the effect of friction and stress, we found that temperature increase occurs in the rock near the fault instead of on the fault, which means the mechanism of temperature increase is stress accumulation. Temperature of fault at the instability position does not increase, which means the position is locked. We speculate that the position of locked area on fault with high stress accumulation near the fault may be the future instability position. It is of significance of studying temperature variation during stick-slip to the monitoring of earthquake precursors. Heat caused by friction of earthquake needs long time to transfer to the surface and could not be detected as a precursor. While the stress of surface rock near the fault would change as the stress of interior rock changes, which could cause detectable temperature variations. The research purpose of this article is to find special change positions before instability. As the temperature variations are caused by stress and slip of fault, the results are also meaningful to analysis of stress and displacement data related to earthquake precursors.  相似文献   

地震监测氡观测仪器校准新方法研究     

任宏微  姚玉霞  黄仁桂  陈兰庆  王桂清 《地震》2016,36(3):46-54

利用国际刻度参考装置AlphaGUARD测氡仪及水氡测量组件, 使用水中溶解氡(或豁免级氡气源), 开展代替目前氡气固体源校准方法实验。 对FD-125测氡仪标配的3个闪烁室(1#、 3#及5#)分别使用水中溶解氡和氡气固体源进行校准实验, 3个闪烁室的校准K值相对误差分别为5.06%, 1.92%及2.76%, 可以达到目前地震监测氡观测技术要求。 实验结果表明, 水中溶解氡代替氡气固体源校准, 可以解决目前氡气固体源校准中存在的运输困难、 维修技术要求高等问题, 是今后氡观测仪器校准技术的发展趋势。  相似文献   

青藏高原可可西里卓乃湖溃堤成因及其影响分析   总被引：8，自引：5，他引：3  

刘宝康  李林  杜玉娥  梁天刚  段水强  侯扶江  任继周 《冰川冻土》2016,38(2):305-311

受青藏高原暖湿化趋势的影响,近年来高原湖泊水位普遍上涨,湖泊溃堤时有发生.利用青藏高原可可西里卓乃湖、库赛湖、海丁诺尔湖和盐湖所在区域的TM（ETM+）等历史文献数据和环境减灾卫星（HJ1A/B） CCD数据,结合五道梁气象站气温、降水资料,分析了卓乃湖周边湖泊面积变化情况.结果表明：1961-2014年近54 a来,可可西里地区持续增加的降水是卓乃湖溃堤的基础,2011年8月22日之前的两次强降水过程和之后的持续降水是导致卓乃湖湖水大量外泄,并最终溃堤的主要原因;溃堤前的两次地震可能对卓乃湖的湖盆结构产生了一定的影响,从而加速了溃堤过程.溃堤导致湖岸线退缩,并产生大片的沙化土地,恶化了藏羚羊的产仔环境,对周边草地生态环境和重大工程设施产生了不利影响.  相似文献   

基于耦合欧拉-拉格朗日法充灌袋挤淤过程的有限元研究     

陈静  闫澍旺  孙立强  陈浩  郎瑞卿  任宇晓  林澍  葛娟 《岩土力学》2016,37(8):2411-2416

在含水率大、承载能力低的软土地基上,利用充灌砂袋进行挤淤置换的方法工艺简单、施工方便、处理效果明显,已经广泛地应用在建造围埝和修筑道路中。充灌袋下沉到一定深度后,其重量与地基承载力相等,从而达到极限平衡状态。充灌袋挤淤所达到的深度与其高度存在一定的对应关系,在工程中确定此关系十分重要。通过3组不同宽度的挤淤模型试验,得到充灌袋下沉量与充灌袋高度的曲线关系、淤泥的位移特性及隆起量。利用ABAQUS中耦合欧拉-拉格朗日法（CEL法）,将充灌袋和淤泥分别用拉格朗日体和欧拉体描述,模拟充灌袋挤淤下沉的过程,将模拟得到的充灌袋下沉深度和高度的关系、淤泥的位移特点与试验结果以及理论公式进行对比。结果表明,CEL法模拟得到的结果与试验结果、理论解具有很好的吻合性,说明利用CEL法可以较好地模拟充灌袋的挤淤问题。  相似文献   

基于Copula函数的CFG桩复合地基载荷-变形曲线的概率分析     

辛军霞  吴兴征  高伟  任国家  马骏翔  范磊 《岩土力学》2016,37(Z1):424-434

CFG桩(cement-fly ash-gravel pile)复合地基是一种重要的地基处理形式,在日益增加的大面积住宅和商业开发中作用越来越突出,然而该种桩型的加卸荷-沉降变形特性仍然需深入研究,尤其在概率评估方面。根据北京星光影视股份有限公司生产科研基地项目工地中的21根CFG桩单桩静载试验和32个复合地基静载试验的原位加卸载测试成果,采用两参数的双曲线或幂曲线回归拟合了每一条加荷-变形曲线。由于土体的内在各向异性和其强度的变异性,评估整个场地的加荷-变形曲线时,其回归参数表现出了较大的离散性。将一个场地的多组回归参数组成一个随机向量,其加载-位移曲线的不确定性可由简单的两变量随机向量体现,引入双变量联结函数（Copula）描述随机回归参数间的相依性。最后,考虑正常使用极限状态,采用基于Copula函数的模拟模型计算了CFG桩复合地基的可靠度指标。研究结果有助于改进CFG桩复合地基的概率设计与评估。  相似文献   

北山花岗岩深部节理间距分布多重分形研究     

薛东杰  周宏伟  任伟光  赵彪 《岩土力学》2016,37(10):2937-2944

岩体节理几何特征定量描述是岩体力学性质和渗透性研究的基础,更是核废料处置库场址筛选和评价过程的主要内容。基于甘肃北山高放废物深地质处置库预选区BS17、BS18和BS19钻孔岩芯节理数量修正数据,针对节理间距建立了类负指数分布数学统计模型,进一步应用于RQD体系定量评价深部岩体完整性,通过与RID体系对比验证了概率模型的可靠性。指出节理数量-间距关系具有明显的分段线性特征,分维数随着间距增大而增大。确定了节理间距-数量关系符合尺度律,得出了数量与间距关系的多重分形特征。进一步分析了数量与埋深的多重分形特征,初步实现了岩芯节理的定量描述。验证了多重分形谱可以很好地统计分形维特征,尤其是节理几何形状及分布特征。该研究结果可为实现基于钻孔岩芯节理几何特征数据的深部岩体节理三维网格模拟提供参考。  相似文献   

海岸带土地发展潜力评价——以杭州湾南岸为例          下载免费PDF全文

陈阳  马仁锋  任丽艳  李伟芳  李加林 《海洋学研究》2016,34(1):27-34

土地潜力评价是编制土地利用规划的前提,把握土地的潜在经济效能是城镇化、工业化快速推进背景下土地资源合理配置的重要命题。本文甄选自然条件、生态敏感性、经济发展和空间结构指标建立了土地发展潜力评价体系,分别采用模糊综合评价法与网络层次分析法赋权指标体系与计算权重,测度发展潜力值并划分了杭州湾南岸余姚、慈溪和镇海的海岸带土地发展潜力区。结果显示:(1)低发展潜力区面积为237.14 km²,占比为17.73%;中发展潜力区面积为323.08 km²,占比为24.15%;高发展潜力区面积为473.34 km²,占比为35.38%;极高发展潜力区面积为304.27 km²,比例为22.74%。(2)按照地类的级别面积分析,交通运输用地和自然保留地面积在极高潜力区中达到峰值,呈由高向低等级面积递减态势;耕地、其他农用地、城乡建设用地和其他建设用地在高潜力区中占比最大,且基本布局于极高、高潜力区;园地、河流水面、水利建设用地集中于中潜力区,而沿海滩涂与林地基本分布于低、中潜力区。(3)余姚、慈溪和镇海海岸带土地发展潜力分区呈现不同特点,余姚属于待提升型,慈溪为均衡发展型,镇海是高质发展潜力型。  相似文献   

松花江流域（吉林省段）产业系统生态效率时空分异特征与影响因素   总被引：1，自引：0，他引：1  

郭付友  佟连军  魏强  张慧敏  仇方道 《地理研究》2016,35(8):1483-1494

在对产业系统生态效率内涵进行阐释的基础上,基于资源消减、清洁生产和末端治理等不同生产环节生态效率要素综合构建了产业系统生态效率测度模型以及产业系统可持续性评价模型,并据此对松花江流域（吉林省段）产业系统生态效率时空演变特征以及影响因素进行了深入分析,研究发现：① 综合型城市侧重于源头消减效率的提高从而使产业变“轻”,总体呈现低投入、低消耗以及低排放的发展特征。资源型城市侧重于清洁生产效率的提高从而使产业变“清”,总体呈现高投入、高利用以及高排放的发展特征。② 产业系统生态效率增长幅度为白城市>松原市>吉林市>松花江流域>长春市,流域特征明显。另外从不同生产环节效率对生态效率的贡献率分析可知,资源减量化以及末端治理是松花江流域（吉林省段）生态效率变化的决定性因素。③ 总体上流域产业系统可持续性有不断增强的趋势,但产业可持续性发展态势分异现象显著。并且产业可持续性发展规律性较差侧面说明了区域产业之间缺乏有效的分工与联系,产业联动发展模式尚未形成。④ 认为所有制结构、环境管理力度、外商投资以及科学技术是松花江流域（吉林省段）产业系统生态效率的影响因素,而经济发展水平、产业结构以及政府调控因素没有通过显著性检验。  相似文献   

Potential promoted productivity and spatial patterns of medium- and low-yield cropland land in China   总被引：2，自引：1，他引：1  

Huimin Yan  Yongzan Ji  Jiyuan Liu  Fang Liu  Yunfeng Hu  Wenhui Kuang 《地理学报(英文版)》2016,26(3):259-271

With a continuously increasing population and better food consumption levels, improving the efficiency of arable land use and increasing its productivity have become fundamental strategies to meet the growing food security needs in China. A spatial distribution map of medium- and low-yield cropland is necessary to implement plans for cropland improvement. In this study, we developed a new method to identify high-, medium-, and low-yield cropland from Moderate Resolution Imaging Spectroradiometer (MODIS) data at a spatial resolution of 500 m. The method could be used to reflect the regional heterogeneity of cropland productivity because the classification standard was based on the regionalization of cropping systems in China. The results showed that the proportion of high-, medium-, and low-yield cropland in China was 21%, 39%, and 40%, respectively. About 75% of the low-yield cropland was located in hilly and mountainous areas, and about 53% of the high-yield cropland was located in plain areas. The five provinces with the largest area of high-yield cropland were all located in the Huang-Huai-Hai region, and the area amounted to 42% of the national high-yield cropland area. Meanwhile, the proportion of high-yield cropland was lower than 15% in Heilongjiang, Sichuan, and Inner Mongolia, which had the largest area allocated to cropland in China. If all the medium-yield cropland could be improved to the productive level of high-yield cropland and the low-yield cropland could be improved to the level of medium-yield cropland, the total productivity of the land would increase 19% and 24%, respectively.  相似文献