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61.
The prefabricated pile,driven in soft clay,can squeeze the soil laterally in a certain scope around the pile,and the void ratio is reduced significantly;consequently,the shear bearing capacity is raised.But the soil parameter,which is used to estimate the capacity of pile,is reduced according to the soil state before the pile was driven.Then,a certain difference appears when the pile is working.The calculation result usually is partial to conservative.This paper analyzes the squeezing mechanism of the pile using the theory of cylindrical cavities expansion.And a formula,which is used to estimate the increment of shear bearing capacity of soil around the pile when excess pore water pressure from pile driving distributes completely,is presented based on the unique relation between the shear bearing capacity and the density of the soil.This formula can be used to estimate the final ultimate-bearing capacity of the pile.The calculated results by the proposed formula are in good agreement with those of the site measurement. 相似文献
62.
真空碳热还原酸浸含钛高炉渣制备TiC分析 总被引:1,自引:0,他引:1
含钛高炉渣中含有20%~30%的TiO 2,是一种附加值较高的二次资源,但在综合利用过程中存在氧化物还原难度大,硅钛难分离,二次污染严重等问题。基于热力学理论基础,采用真空碳热还原联合酸浸工艺处理含钛高炉渣制备TiC。结果表明:真空有助于钛氧化物彻底还原,可实现渣中硅钛彻底分离,减少酸耗量,降低二次污染。真空碳热还原联合酸浸工艺处理含钛高炉渣(TiO 2含量23%左右)制备TiC的最佳条件为:炉渣粒度200目,还原温度1 673 K,渣碳质量比100∶38。 相似文献
63.
夏播大豆品种的生育期特性与农艺性状的关系分析 总被引:2,自引:0,他引:2
从 339个大豆品种中选取生育期小于 1 0 0d的 1 0 3个品种进行生育期结构特性与农艺性状的分析。结果表明 :①R1最长的为华北品种 ,最短的为外国品种 ;②R7最长的为东北品种 ,最短的为南方品种 ;③R1与生育前期即营养生长阶段 ,高纬地区长于低纬地区 ;R7与生育后期即生殖生长阶段 ,低纬地区长于高纬地区 ;④R1、生育前期长的品种 ,单株荚数、单株粒数多 ,株高较高 ;R7、生育后期长的品种 ,百粒重高 ;⑤筛选出一批对光温不敏感的品种 相似文献
64.
65.
66.
西藏冬小麦成穗率与气候条件的关系 总被引:1,自引:0,他引:1
在系统分析研究西藏自治区山南地区多年气候因子对冬小麦成穗率的影响规律基础上,建立了成穗率气候模型。结果表明:山南地区冬小麦三叶一分蘖期间的平均气温偏高有利于成穗率的增加;分蘖一拔节期空气干燥将减少成穗率;孕穗一抽穗期的空气湿度为49%左右、日较差小、阴雨寡照有利于成穗率的提高。 相似文献
67.
为了在黄河中、上游地区加快实施中央“退耕还林还草恢复生态环境”的决策,正确估算区域人口的承载量是一项基础性的研究工作。以山西省和山西省黄河流域为研究区域,利用相关统计、试验数据,设计不同草地利用率层次和不同肉食消费水平等次,对山西省和山西省黄河流域及其各县市草地资源人口承载量进行了单项和组合型的动态变化研究,为山西省区域退耕还林还草和生态移民工作提供了理论基础。 相似文献
68.
Two monolayer concrete frames with the same reinforcement, KJ1 and KJ2, were designed. KJ1 was designed to simulate low cyclic reversed loading test under weak earthquake. Besides, the fire response test, including temperature rising and lowing, was made by fixing the axial compression ratio of the column. For KJ2, the fire response test at the fixed axial compression ratio was made. The deformation response of the concrete frames in fire was studied. Comparative analysis of the apparent phenomenon, temperature curves, bearing capacity change of the frames were made based on the test results of KJ1 and KJ2. According to the simplified temperature distribution, the ultimate bearing capacity of the column under the high temperature was preliminarily determined. It is illustrated that the calculation results and finally test phenomenon are consistent according to the simplified section. 相似文献
69.
Ana I. Martín-Vertedor Juan M. Pérez RodríguezHenar Prieto Losada Elías Fereres Castiel 《Agricultural Water Management》2011,98(6):950-958
To understand the relations between water use and yield in response to crop load, two experiments were conducted in olive (cv. Morisca), during six consecutive years (2002-2007) in an experimental orchard located in Badajoz, Southwest Spain. Experiment 1, assessed the responses during the early years of the orchard (2002-2004) using four irrigation treatments that applied fractions of the estimated crop evapotranspiration (ETc) (125%, 100%, 75% and 0%) and three crop load levels (100%, 50% and 0% of fruit removal, termed Off, Medium and On treatments). Experiment 2 assessed the response of more mature trees (2005-2007) to three irrigation treatments (115%, 100%, and 60% of ETc) and the natural crop load which were Off, On, and Medium in 2005, 2006 and 2007, respectively. Yield was reduced by water deficits and so did the estimated tree transpiration which was linearly related to yield (y = 1.2302x − 21.15, R2 = 0.8864), showing the high sensitivity of cultivar Morisca to water deficits. The relations between fruit number and fruit weight showed that high crop loads had lower fruit weights and oil yield, a decrease that was more pronounced as water deficits increased. The yield response to water supply in the control and excess treatments, and the observations on the water relations of these two treatments suggest that the calculations made using the FAO method (Doorenbos and Pruit, 1974) with the crop coefficient proposed by Pastor et al. (1998) and the reduction coefficient (Fereres et al., 1982) to apply 100% of ETc in the control treatment, underestimated the ETc of the orchard. The results indicate that, although the absence of fruits lead to reduced water use as compared to situations of medium and high crop loads, canopy size was much more determinant of orchard water requirements than crop load. 相似文献
70.
本文的调查和观测结果表明:山杏以中、长果枝结果为主,株间自然传粉是结实的主要途径,自然落果发生在果实速长期。山杏果实及其各部分的生长动态均呈“S型曲线。各部分出现生长高峰的时期大致分三个阶段:第一阶段是果实、果核和胚珠的迅速增大,以及青皮和核壳的迅速增长;第二阶段是胚的迅速增长;第三阶段是胚中干物质量的迅速增长。硬核期从果实基本停长后的5月下旬开始,至6月中旬结束,此期胚球已达到成熟时的大小。 相似文献