The penetration experiment to predict liquefaction resistance of reclaimed soils     

Jing-Wen Chen  Fu-Cheng Chen 《Ocean Engineering》2008,35(3-4):380-392

The liquefaction resistance of the soils used to be estimated through the in situ tests, such as standard penetration test and cone penetration test; or by means of cyclic triaxial test in laboratory. However, both in situ tests and cyclic triaxial test are time-consuming and costly; this study introduces a quick and cost-effective method to evaluate the liquefaction resistance of soils under certain confining pressure in laboratory. A particular device modified from the conventional triaxial compression test apparatus, namely “Triaxial Cone Penetration Test”, was developed to obtain the peak values of cone resistance in soils so as to correlate the liquefaction resistance of the reclaimed soils evaluated by cyclic triaxial tests. The test result indicates a good correlation between the peak value of cone resistance and the corresponding cyclic stress ratio (CSR) at the state of initial liquefaction, in which the correlation for loose samples is better than that for dense samples. Besides, both peak values of cone resistance and corresponding CSR increase with fine content of soils reaches 10% and decreased with fine content varying between 10% and 50%. By examining the compositions of the soils with scanning electron microscopy and X-ray diffraction, it is found that the proportion and characteristics of the fines plays an important role on the liquefaction resistance of the reclaimed soils.  相似文献   

关中盆地地下水环境地质问题研究     

石卫  王友林  杜少少 《地下水》2014,(2):54-56

陕西关中盆地做为西部大开发的一个核心支撑区,而水资源紧缺成为经济进一步发展的制约因素。根据盆地内主要城市地下水的开采利用现状及供水结构变化,系统地分析盆地内的地下水不合理开采所导致地下水降落漏斗、地裂缝、地面沉降、渍水及土壤盐渍化等环境地质问题,最后提出可行的防治措施,以恢复生态环境良性循环。  相似文献   

黄河三角洲地下水动态变化及其与地面沉降的关系          下载免费PDF全文

刘勇  李培英  丰爱平  黄海军 《地球科学》2014,39(11):1555-1565

为了分析黄河三角洲地下水动态及其与地面沉降的关系, 利用多年地下水和地面沉降监测数据, 发现黄河三角洲广饶县和东营区的地下水动态变化剧烈且地面沉降严重, 含水层多处于超采状态, 浅、深层地下水降落漏斗先后出现.深层地下水降落漏斗中心水位下降速度达2~3m/a.近年来, 东营和广饶地面沉降漏斗中心沉降量和速率分别为155.1mm、28.2mm/a和356.0mm、64.7mm/a.借助GIS技术及数理统计法, 发现深层地下水降落漏斗与沉降漏斗空间耦合良好, 深层地下水位与地面高程呈线性正相关, 相关系数为0.92, 深层地下水过度开采已成为影响沉降的最根本因素.井灌区第三粘性压缩层成为地面沉降主要贡献层, 且深层地下水降落漏斗中心的地下水位已低于第三承压含水层临界水位, 沉降趋于严重.   相似文献   

潜水含水层水压力传递的时效性     

卢玉东 《地球科学与环境学报》1997,(Z1)

传统的渗流模型研究中，忽略了渗流场中水压力传递的时效性。本文针对潜水含水层井流问题，分析了井流场的特征。在前人研究的基础上，作者详尽地推导了上部入渗补给为常量情况下的降落漏斗半径和水压力传递速度与时间的关系式，并对某电厂水源地进行了计算。  相似文献   

Anatomical Study of Cretaceous, Permineralized, Bennettitalean Fossils from Heilongjiang Province, NE China     

LIU Fengxiang  YANG Xiaonan  CHENG Yeming 《《地质学报》英文版》2022,96(5):1495-1501

Well-preserved Cretaceous trunk fragments of Cycadeoidea (Cycadeoidaceae) were recently found in Keshan County, Heilongjiang Province, Northeast China. These fossils represent important evidence of the distribution of this group of plants in East Asia. In these trunk fragments, the stem cortices and leaf bases with cones are preserved. The leaf bases are rhombic with cones infrequently distributed among leaf bases. The cortex is broad and consists of fundamental parenchyma cells, numerous secretory ducts and C-shaped leaf traces with adaxial secondary xylem and abaxial secondary phloem. The genus Cycadeoidea, which is widely distributed in the Cretaceous deposits of East Asia, North America and Western Europe, was an important component of Cretaceous floras. Bennettitalean trunk fossils with well-preserved anatomical structures are rarely known from China. These fossils are important for studies of the evolution of genus Cycadeoidea and for stratigraphic correlation.  相似文献   

绳索取心深孔偏心楔同径侧钻绕障技术实践          下载免费PDF全文

王红阳  罗永贵  腾新明 《探矿工程》2015,42(6):17-20

招远市栾家河金矿区 47ZK3孔设计孔深2570 m,于孔深2297 m处发生跑钻事故,处理至孔内事故底部时,处理难度增大。为加快事故处理进度,降低事故损失,采用偏心楔侧钻技术进行同径造斜的方法,绕开事故段。通过对偏心楔设计、偏心楔制作与安装、造斜钻头及分支钻进钻头选择等技术措施进行优化,较好地解决了偏心楔侧钻过程中偏心楔固定及过斜面工序的关键技术问题,顺利地将分支孔延伸至终孔。  相似文献   

罗布泊红柳沙包落叶阳离子含量及环境指示意义   总被引：1，自引：0，他引：1       下载免费PDF全文

沈睿媛  李秀丽  夏训诚  赵元杰 《干旱区地理》2012,35(1):109-115

 红柳沙包沉积纹层是恢复古环境序列的一种新方法。通过对罗布泊地区红柳沙包沉积纹层中红柳落叶阳离子含量以及与环境变化关系研究表明：K+、Na+、Ca2+、Mg2+等4种阳离子平均含量分别为3.70 mg/g、40.33 mg/g、13.67 mg/g和8.08 mg/g,变化幅度排序为Ca2+ > K+ > Mg2+ > Na+。4种阳离子含量年际变化都较为明显,且变化规律较为一致,4种阳离子含量变化间的相关系数为0.653 0 ~ 0.813 8,表现为良好的正相关关系;各种阳离子与4种阳离子总量变化的相关系数为0.814 4 ~ 0.959 9,其中Na+含量与4种阳离子总量变化的相关系数最高,表明可以用Na+含量的变化或阳离子总量的变化分析变化趋势。阳离子含量与气温变化呈良好的正相关、与年降水量和湖水面积变化呈负相关;地下水水位降低、水质变差时,土壤水质也变差,阳离子含量增加;反之,地下水水位升高、水质变好时,土壤水质变好,阳离子含量降低。红柳落叶有机质阳离子含量的变化进一步验证了利用红柳沙包沉积纹层计年的可靠性和对罗布泊环境变化的可行性。  相似文献   

Experimental study on the effect of bottomless structure in front of a bottom outlet on a sediment flushing cone     

Hadi Haghjouei  Majid Rahimpour  Kourosh Qaderi  Sameh AKantoush 《国际泥沙研究》2021,36(3):335-347

One of the main problems in reservoirs is sedimentation which reduces the operating life of dams if a proper plan and analysis method are not in place.The techniques to manage sediment in reservoirs include several sustainable management techniques that route sediment through or around the reservoir.One of the main economical methods in arid and semi-arid regions is pressurized flushing using moderate drawdown of the water level of the reservoir to evacuate sediment deposited behind dams.In the current study,the effect of a new structure called a dendritic bottomless extended(DBE)outlet structure at three angles of 30°,45°,and 60°
on pressurized flushing efficiency was investigated.Consequently,45 experiments were designed for three discharge rates (Qo),three sediment levels(Hs),four types of structure,and a no-structure condition(reference test).The results indicated that the DBE structure with a 30°angle between the branches,a sedimentary dimensionless index of Hs/Do=4.59,and a flow dimensionless index of Qo=/√gD05=1:43(where g is the acceleration of gravity and Do is the diameter of the bottom outlet)lead to 10-fold increase in the sediment flushing cone dimensions and sediment removal efficiency compared to the results of the reference test.Finally,according to a statistical analysis of the results,a dimensionless equation for calculating the sediment flushing cone dimensions was developed for the tested sediment characteristics.  相似文献   

基于2011年新西兰地震的CPT液化特征研究          下载免费PDF全文

张思宇  李天宁  李兆焱  袁晓铭  卢坤玉 《世界地震工程》2021,(3):170-179

2011年2月22日,新西兰第二大城市克赖斯特彻市附近发生M_s6.3级地震,震中位于克赖斯特彻市西南10km处,震源深度为5km。地震造成了大量的人员伤亡和经济损失,重建费用估计高达40亿新西兰元,得到共识是砂土液化为震害主因。此次地震,液化震害极为严重,喷砂冒水范围广泛分布于城市内外,引起大量次生灾害,地震也为砂土液化特征研究,特别是检验和发展液化判别方法提供了大量宝贵的液化数据。本文收集整理震后132个勘察点的勘察资料,包括静力触探试验（以下简称"CPT"）数据、地表峰值加速度和地下水位等。通过对数据的研究,得到了地震液化场地加速度分布、地下水位分布和砂层埋深分布等特征。检验了我国现有的静力触探试验液化判别方法,结果表明:液化场地主要分布在PGA为0.5~0.65g附近,液化层5m以内居多,我国CPT液化判别方法对于10m以下判别存在明显的错误,同时此次地震还发现多个液化层位于20m以下,对于这个深度,国内CPT液化判别方法还未涉猎。  相似文献   

膨胀式尾管悬挂器的研究          下载免费PDF全文

崔淑英  邵玉涛  王跃伟  宋刚 《探矿工程》2019,46(2):65-70

为了解决常规尾管悬挂器过流面积小、密封性能差的缺点,研究了膨胀式尾管悬挂器。主要对膨胀式尾管悬挂器的工作原理,结构原理,关键技术包括替浆技术、固井技术、膨胀悬挂技术、丢手技术进行了研究;解决了膨胀管悬挂的一系列技术难题;对膨胀管受力进行了有限元分析,并将结果与室内试验进行了对比,两者结果基本一致。通过野外试验进一步证明了膨胀式尾管悬挂器能够提供足够的悬挂力,满足悬挂要求。  相似文献