长春万达广场抗浮锚杆的设计与试验研究     

张有  冯永光  欧阳永龙  张勇  郭峰峰  周志明 《中国煤炭地质》2012,(12):33-36

以长春万达广场地下室抗浮锚索工程为例,研究了扩体拉力型锚杆支护在宏观上和微观上的力学作用机理、扩体型锚固体的设计计算、所采用的锚杆扩体部分的扩孔器的内部结构等。在实验结果基础上,得出在土层中采用扩体型锚杆不仅能充分利用土体自身的强度,提高其承载力,改变其锚固体的应力状态,而且能减少锚杆锚固体长度、缩短施工工期、降低工程成本、节约自然资源等结论。最后对扩体型锚索影响承载力的因素、地层适用条件以及它的应用前景进行了探讨和展望。  相似文献   

Determining air permeability in reclaimed coastal land based on tidal fluctuations     

Jian Li  Hongbin Zhan  Guanhua Huang  Kehua You 《Environmental Earth Sciences》2012,66(4):1259-1268

Coastal land reclamation is a common practice in many regions around the World. A reclaimed coastal land often has a two-layer system: a highly permeable layer consisting of crushed rock fragments underneath a less permeable layer. This study deals with vertical airflow in a reclaimed coastal land induced by the periodic variations of water table elevation due to tide fluctuations. The influence of atmospheric pressure fluctuations can be easily dealt with through a simple superposition procedure reported by Li and Jiao, thus is not considered here. A time-series Fourier analysis method is developed to determine air permeability based on a tide-induced airflow model reported by Li and Jiao for the reclaimed coastal land. This method employs the amplitude attenuations of subsurface air pressure to search for values of dimensionless air-leaking-resistance which can be subsequently used to calculate air permeability. Two types of data, the air pressure data in the upper less permeable layer and the tidal fluctuation data, are required to calculate the air permeability. Type curves relating to the amplitude attenuations and the relative depth can also be used to determine the values of air permeability. A field site in Hong Kong International Airport is used to demonstrate the applicability of this method for reclaimed coastal land consisting of a marine sand layer above a layer of crushed rock fragments. The application shows that the amplitude attenuations of diurnal and semi-diurnal components in the Fourier series are most reliable for determining the value of air permeability.  相似文献   

塔里木盆地柯坪地区中上寒武统白云岩沉积微相   总被引：1，自引：1，他引：0       下载免费PDF全文

刘玲  朱井泉  由雪莲  何凯 《古地理学报》2012,14(1):33-43

在塔里木盆地西北缘柯坪地区的蓬莱坝剖面发现一套完整的寒武系白云岩地层,对其进行了系统的野外测量、岩性描述、样品采集和镜下观察,作出了完整的地层岩性沉积相综合柱状图,并对其进行沉积相、亚相和微相的分析.在该剖面中,识别出1种相——碳酸盐岩台地相,并进一步分为3种亚相和6种微相,分别为:开阔台地亚相(开阔潮坪、颗粒滩)、局...  相似文献   

近30年中国东北地区玉米种植体系的时空动态分析(英文)   总被引：5，自引：1，他引：4  

谭杰扬  杨鹏  刘珍环  吴文斌  张莉  李志鹏  游良志  唐华俊  李正国 《地理学报(英文版)》2014,24(3):397-410

Understanding crop patterns and their changes on regional scale is a critical requirement for projecting agro-ecosystem dynamics. However, tools and methods for mapping the distribution of crop area and yield are still lacking. Based on the cross-entropy theory, a spatial production allocation model(SPAM) has been developed for presenting spatio-temporal dynamics of maize cropping system in Northeast China during 1980–2010. The simulated results indicated that(1) maize sown area expanded northwards to 48°N before 2000, after that the increased sown area mainly occurred in the central and southern parts of Northeast China. Meanwhile, maize also expanded eastwards to 127°E and lower elevation(less than 100 m) as well as higher elevation(mainly distributed between 200 m and 350 m);(2) maize yield has been greatly promoted for most planted area of Northeast China, especially in the planted zone between 42°N and 48°N, while the yield increase was relatively homogeneous without obvious longitudinal variations for whole region;(3) maize planting density increased gradually to a moderately high level over the investigated period, which reflected the trend of aggregation of maize cultivation driven by market demand.  相似文献   

Characteristics of a drainage channel with staggered indented sills for controlling debris flows   总被引：2，自引：1，他引：1  

Xiao-qing Chen  Yong You  Jian-gang Chen  Kai Huang  De-ji Li 《山地科学学报》2014,11(5):1242-1252

The characteristics of a new type of drainage channel with staggered indented sills for controlling debris flows were studied. The intermediate fluid in the non-viscous debris flow exhibited a helical movement, whereas the fluid near the sidewall had a stop-start movement pattern; the viscous debris flow exhibited a stable structure between the indented sills. The experimental results indicate that the mean velocity of the debris flow increased with increasing channel gradients, and the debris flow velocity was slightly affected by the angle of the sills. The average velocity of the non-viscous debris flow increased in the range of(0.5–1.5) interval between the indented sills, whereas the average velocity of the viscous debris flow increased initially and then decreased in the range of(0.75–1.25) interval between the indented sills. The depth of the non-viscous debris flow tended to gradually increase as the channel gradients increased, whereas the depth of the viscous debris flow gradually decreased as the channel gradients increased. When the discharge of the debris flow was constant, the angle and the interval between the indented sills had a slight effect on the depth of the viscous debris flow, whereas the depth of the non-viscous debris flow exhibited a different trend, as the sill angles and intervals were varied.  相似文献   

基于改进U-Net卷积神经网络的储层预测          下载免费PDF全文

陈康  狄贵东  张佳佳  周游  吴尧  张广智 《CT理论与应用研究》2021,30(4):403-416

传统的U-Net卷积神经网络大多存在深层网络梯度消失的问题。本文在U-Net卷积神经网络中加入残差模块,提出了一种改进U-Net卷积神经网络。残差模块保证了U-Net卷积神经网络在误差反向传播过程中梯度的存在,在一定程度上可以缓解梯度消失的问题。最后将改进U-Net卷积神经网络应用于实际储层预测中,实际数据测试结果表明基于改进U-Net卷积神经网络在岩性识别以及“甜点”预测上均能取得较好的效果。   相似文献   

张掖盆地壳内电性结构研究     

张优  安志国  董艳辉 《地球物理学进展》2021,36(4):1477-1486

张掖盆地处于青藏高原东北缘,探究该区域的构造活动对于研究青藏高原向东北方向碰撞挤压机制具有重要意义.此次布设3条北东向宽频大地电磁剖面,基于实测数据,通过Bahr分解、相位张量分析和共轭阻抗变换的方法进行了偏离度分析和电性主轴分析;通过NLCG二维反演,获得了沿剖面的电性结构模型.结合研究区地质与地球物理资料进行分析,结果表明:电性结构模型在横向上呈现出分块特点,榆木山和龙首山隆起区对应高阻,走廊过渡带整体表现为低阻;走廊过渡带中存在一壳内低阻层,表现为壳内滑脱;祁连地块中上地壳整体表现为高阻,下地壳电阻率相对较低,以推覆拓展样式延伸至河西走廊地区;阿拉善地块呈"低阻舌状体"俯冲于河西走廊下部,整体形态呈南浅北深.  相似文献   

基于深度学习的接收函数自动挑选方法     

李志强  田有  赵鹏飞  刘财  李洪丽 《地球物理学报》2021,64(5):1632-1642

接收函数作为地震学研究中的重要方法之一,在间断面成像、S波速度结构反演方面应用广泛.然而,接收函数方法需要耗费大量的人工成本挑选可用的数据,这不利于我们快速准确地获得地下结构,因此发展快速准确的数据自动处理方法具有十分重要的意义.本文针对这一问题,提出利用深度学习方法自动挑选接收函数,并使用中国地震局的牡丹江地震台(MDJ)和北京地震台(BJT)于2000年至2019年记录的波形数据提取的接收函数进行试验.结果表明,应用深度学习方法挑选接收函数是可行的,使用自动挑选的接收函数对台站下方地壳结构进行估计,结果与使用人工挑选的接收函数估计的结果具有较高的一致性.通过使用不同样本比例的训练集和测试集进行分析,本文提出的方法具有对训练集的数据量要求较低、利用率高、适合多台数据联合训练等特点.该方法在建立台网接收函数自动挑选模型字典、区域接收函数自动挑选模型等方面具有巨大应用潜力.  相似文献   

基于地震观测数据的结构损伤水平表征参数研究     

杨永强  杨耀鑫  杨游  左占宣  公茂盛 《地震工程与工程振动》2022,42(2):42-51

为了能在震后更好地利用测得的结构动力响应参数快速对结构损伤程度进行评估,文中挑选了最大层间位移角、自振频率相对改变量和顶层加速度放大系数3个参数,分析结构损伤指数与3个参数之间的相关性,并且提出了一种组合结构体系参数.结果表明,结构损伤指数与最大层间位移角的相关性为高度相关,与自振频率相对改变量和顶层加速度放大系数的相...  相似文献   

公元前2500年:中国进入铜石并用时代的汞记录   总被引：1，自引：5，他引：1       下载免费PDF全文

徐利斌  孙立广  张居中  朱仁斌  游科华  王吉怀 《第四纪研究》2008,28(6):1070-1080

对安徽蒙城尉迟寺遗址剖面5050～4000cal.aB.P.间的汞记录研究表明,剖面中Hg的累积速率主要是由大气沉降影响的。在5050～4550cal.aB.P.间,YC1剖面中的汞的累积速率相对较低,并且主要是受气候控制:气候越寒冷,剖面中汞的累积速率则越高;在4530～4000cal.aB.P.间,YC1剖面中汞的累积速率显著升高,此时影响剖面中汞的累积速率的主要因素是人类活动——中国古代人类社会的原始金属冶炼活动,原始金属冶炼活动的规模直接决定了剖面中汞的累积速率。Hg在距今4500年前后的显著上升,标志着中国已经进入了铜石并用时代。  相似文献