Construction Stage Analysis on Replacement of Closure Segment in Prestressed Concrete Cable-stayed Bridges

To deal with failure of wet joint between a closure segment and its neighboring segments of main girder in an existing prestressed concrete cable-stayed bridge, the technology on replacement of closure segment was presented. In order to analyze structural characteristics of this technology, its technical approaches and construction key points were introduced. Then a FEM model for a typical prestressed concrete cable-stayed bridge was established, and a construction stage analysis method was given in detail, including establishing a structural basement calculation model for replacement of closure segment and simulating its construction procedures. Based upon calculation results, variations of some structural state parameters with construction stages, such as deck deflection of main girder, longitudinal horizontal displacement at the top of pylons, cable forces, were analyzed. The results showed, this method could reflect actual change process of structural state and existing inspected results of cable-stayed bridge, and FEM results could well meet with construction monitoring results during replacement of closure segment. Thus variations of structural characteristics with construction stages could actually be revealed. This method could provide references for design and construction control of replacement of closure segment in existing prestressed concrete cable-stayed bridges.     

Experimental Research on the Shock and Wearing Resistant Concrete Blended with Polypropylene Fiber

The shock and wearing resistances and anti-crack performance of concrete blended with polycarboxylate superplasticizer and polypropylene fiber were studied.Results show that,compared with concrete added with silica fume,the high water-reducing effect of polycarboxylate superplasticizer and fly ash reduced the consumption of cementitious material and the amount of cracks decreased significantly.Together with the action of polypropylene fiber,the shock and wearing resistances and anti-crack performance of concrete enhanced remarkably.     

不同棉花品种苗期低钾胁迫响应研究

在液培条件下,对12个棉花品种进行了钾高效品种筛选研究。结果表明,不同棉花品种耐低钾能力不同,其中泗阳328、金106、金农棉3号、隆杂棉2号为钾高效品种,具有钾积累能力强、干物质积累多、钾利用指数高等特点;而湘杂棉7号、金102、隆杂棉1号、湘农棉8号与此相反。钾高效品种叶绿素含量均高于低效品种,说明钾高效棉花品种具有较强向地上部转运钾的能力,从而能维持棉株叶片叶绿体的生理功能;随着钾浓度下降,钾高效品种丙二醛含量低于低效品种,表明钾高效品种自身膜系统稳定性较好,在遭遇低钾胁迫时其抗逆性较强。     

不同杉木种源在贵州省适生栽培区高生长及稳定性分析

杉木在我国有广泛的分市区。以北纬21°41′至北纬34°03′,东经101°45′至东经121°53′之间的广阔亚热带区域都有杉木的自然分布。由于长期的自然条件和漫长的自然选择影响,必然产生了对各种生态因子要求各异的群体,这些不同群体如在分布区内不同生态区进行交流,很有可能会产生各种各样的适应程度表现。 我国目前杉木引种已很普遍。选择生长量高且具有稳定增产效益的引种对象,已是人们日益关心的问题。本文对贵州省已有栽培的来自全国各地共64个种源在贵州省不同栽培地点稳定性进行分析,结合差异分析,为贵州省不同地区的杉木种子调拨区划提供数量化依据。     

Research on Preparation of Non-Autoclaved Aerated Concrete with Phosphorus Slag

In order to prepare aerated concrete with alkali-phosphorus slag and better use of industrial waste, the powder composition of the slurry was investigated. The impacts of certain factors on aerated concrete, including the foaming agent, sodium silicate modulus, alkali content and the temperature of alkali solution also were investigated using single-factor test methods. The results indicate that: the cement and fly ash in powder have impacts on the pouring stability of slurry, and the bulk density of aerated concrete is impacted by the amount of foaming agent, sodium silicate modulus and alkali content. In the experiment, aerated concrete with bulk density in range of 535~887 kg/m3 and compressive strength of 6~9.5 MPa was produced; its mechanical performance conforms to the requirements of the standard GB 11968 2006.     

Experimental Research on Mechanical Behavior of High-strength Concrete Short Columns Confined with Stirrups

Based on the test of high strength concrete (HSC)short columns confined with stirrups 8 under axial loads and 6 under small eccentric loads, the influence of stirrups confinement on stressstrain relationship and related parameter under monoaxial compression are studied, and the effect of the type of stirrups, stirrup ratio, etc. on the HSC columns ductility is analysed. Besides, the strength and deformation behavior of HCS columns under small eccentric compression are explored.Based on the experimental study, the complete stress-strain curves of confined HSC and the formula for calculating the related parameter are presented in this paper.     

镉胁迫对不同基因型大白菜苗期生长及镉积累的影响

利用实验室营养液水培法,研究了在不同浓度Cd胁迫下5个大白菜品种苗期生长和吸收积累镉的差异.结果表明,在不同浓度Cd胁迫下,各品种地上部鲜重均下降,且显著低于对照;50μmol/L CdCl2处理时,以浙白8号的生长抑制率最低(53.86％).短期较高浓度的Cd胁迫对大白菜地上部干物质积累有促进作用;在不同浓度Cd胁迫下,品种间大白菜地上部镉含量存在显著差异,其中,浙白8号大白菜地上部镉含量较低( 145.1 mg/kg DW,249.7 mg/kg DW).Cd胁迫下各品种大白菜叶绿素含量均下降,在不同Cd浓度下叶绿素a/b变化不同.     

磷胁迫下不同基因型大豆苗期根系形态及生物量的差异

在磷胁迫[0mmol/L(P),砂培]条件下,对不同基因型大豆苗期在根系形态、生物量等方面的差异进行了研究,结果表明:磷高效基因型在两叶期并未发挥出其基因型潜力的优势;四叶期,磷高效基因型的侧根数、侧根长、根系吸收面积、茎叶干重等性状的受抑制程度均显著低于磷中、低效基因型,而地下干重、根冠比却受到了较中、低效基因型更强的诱导作用。综合评价表明,磷高效基因型的综合值(评价磷效率特性的综合指标)显著高于磷中、低效基因型,显示出了较强的抗磷胁迫能力,但磷高效基因型并非所有性状都表现突出;四叶期可作为大豆耐低磷胁迫的筛选期,根表面积和活跃吸收面积可作为衡量磷效率特性的特异性指标。     

磷胁迫下不同基因型大豆苗期根系形态及生物量差异的研究

在磷胁迫[0mmol/L(P),砂培]条件下,对不同基因型大豆苗期在根系形态、生物量等方面的差异进行了研究,结果表明：磷高效基因型在两叶期并未发挥出其基因型潜力的优势;四叶期,磷高效基因型的侧根数、侧根长、根系吸收面积、茎叶干重等性状的受抑制程度均显著低于磷中、低效基因型,而地下干重、根冠比却受到了较中、低效基因型更强的诱导作用。综合评价表明,磷高效基因型的综合值（评价磷效率特性的综合指标）显著高于磷中、低效基因型,显示出了较强的抗磷胁迫能力,但磷高效基因型并非所有性状都表现突出;四叶期可作为大豆耐低磷胁迫的筛选期,根表面积和活跃吸收面积可作为衡量磷效率特性的特异性指标。     

不同施氮时期对冬小麦根系衰老的影响

采用温室盆栽和田间土柱栽培的方法研究了不同施氮时期对冬小麦根系衰老的影响。结果表明,冬小麦根系从开花后14天开始加速衰老,与籽粒灌浆速率高峰期相对应。20～40cm和40～100cm土层根衰老迟于0～20cm土层根。根系衰老与旗叶衰老、及与籽粒灌浆速率密切相关。20～40cm和40～100cm土层中的根对旗叶衰老有较大影响;在籽粒形成期,0～20cm土层根对粒重形成的作用大,到灌浆期,20～40cm和40～60cm土层根对粒重形成起重要作用。鲁215953和鲁麦14品种分别于拔节期和挑旗期追施氮肥,可延缓小麦根系的衰老,提高籽粒灌浆速率,增加粒重和产量。     

Changes in Water Status,Membrane Stability and Antioxidant Capacity of Wheat Seedlings Carrying Different Rht‐B1 Dwarfing Alleles under Drought Stress

Water deficiency is a major constraint to wheat productivity in drought prone regions. The wheat DELLA‐encoding height‐reducing genes (Rht) are associated with significant increase in grain yield. However, the knowledge of their benefit in dry environments is insufficient. The objective of the study was to examine the effect of induced drought on leaf water content, level of oxidative stress, cell membrane stability, accumulation of osmoprotectants and activity of some antioxidant enzymes in wheat near‐isogenic lines carrying the alleles Rht‐B1b (semidwarfing) and Rht‐B1c (dwarfing) in comparison with the tall control Rht‐B1a. Six‐day‐long water deprivation was imposed at seedling stage. Plants carrying Rht‐B1c and, to a lesser extent, those carrying Rht‐B1b performed better under stress compared with Rht‐B1a in terms of more sustained membrane integrity, enhanced osmoregulation and better antioxidant defence. These differential responses could reflect pleiotropic effects of the Rht‐B1 gene associated with the accumulation of the mutant gene product, that is, altered DELLA proteins, or might be related to allelic variations at neighbouring loci carrying candidate genes for proteins with a major role in plant water regulations and stress adaptation. These findings might be of importance to breeders when introducing Rht‐B1 alleles into wheat cultivars designed to be grown in drought liable regions.     

Numerical Analysis on Stability of Rock in Sijiaotian Tunnel

The Sijiaotian Tunnel in Yunnan Dabao Highway lies in the narrow defile landscape,and the engineering geology condition is complex,with plenty of cienega.According to the actual situation of the Sijiaotian Tunnel Project in Yunnan Dabao Highway,the stability of the surrounding rock mass is studied by using a 3-D non-linear FEM.The Drucker-Prager criterion is chosen as the failure criterion of the rock.The relatively dangerous zone and the monitoring points in the tunnel are determined.The numerical results show that the Sijiaotian Tunnel is relatively stable.The conclusion has some significance for guiding the construction of similar projects.     

不同小麦品种内源激素变化动态及其与分蘖发生关系的研究

１９９７～１９９９年在大田条件下用ＥＬＩＳＡ方法研究了具有不同分蘖特性的小麦品种分蘖发生与分蘖节内源吲哚乙酸（ＩＡＡ）及细胞分裂素类物质－－玉米素核苷（ＺＲ）和玉米素（Ｚ）的关系。结果表明：不同分蘖特性的小麦品种在分蘖发生过程中其ＩＡＡ和ＺＲ＋Ｚ的动态变化明显不同;不同品种的分蘖特性与ＩＡＡ／（ＺＲ＋Ｚ）比值有密切的相关关系;春性小麦分蘖初期较高的ＩＡＡ／（ＺＲ＋Ｚ）比值利于小麦分蘖发生,冬性小麦分蘖初期较低的ＩＡＡ／（ＺＲ＋Ｚ）经值利于小麦分蘖的发生。     

Study on Influence of Mineral Admixture on Chloride Ion Penetration and Diffusion in Concrete

In this paper, the influences of different kinds and different amount of mineral admixture to Cl-penetration and diffusion in concrete are studied. The results of experiment show that separate addition of mineral admixture (ground fly ash, slag fines, silica fume) into concrete can improve its resistance to chloride ion penetration and diffusion. Furthermore,the effect of silica fume is the best, fly ash second, and then follows slag fines. Mechanism analysis shows that the pozzolanic effect of mineral admixture improves the interface between the cement and aggregate in concrete, reduces the total porosity, makes pores more smaller, on the other hand it increases the Cl-consolidation capability of concrete with low alkaline C-S-H gel produced. So the resistance to chloride ion penetration of concrete is improved.     

冬小麦抗逆栽培技术原理的研究 Ⅱ不同生育期重施氮肥对冬小麦生育和抗逆性的影响

本文通过不同生育期重肥N肥对小麦器官建成、光合产物分配与籽粒蛋白质含量等的影响,明确了造成小麦贪青、倒伏的“危险施肥期”和施用N肥的“最大效益期”,并对如何防止贪青、倒伏,增强抗逆性,提高产量和品质等安全、经济施用N肥的技术问题进行了初步探讨.结果表明:1.冬小麦生育前期(注1)施N过多,是造成田间群体大、基部节间长、成穗率低、穗小粒少、千粒重低、生育延迟等的主要原因.因而生育前期是引起冬小麦贪青、晚熟和倒伏的“危险施肥时期”,也叫“N素的过剩敏感期”.2.冬小麦生育前期不施N或者底施N“不过量” 时,生育中、后期重施N肥不仅不会引起贪青、倒伏,而且能大大提高小麦后期的光合生产率和抗逆性,达到成穗率高、小穗退化少和提高粒重的明显效果,使抽穗后的干物质生产量达到籽粒产量的90%左右,尤其是春五叶露尖的中期施肥(即拔节肥)可明显提高小麦产量.因此,拔节期是冬小麦的“N素最大效益期”,也叫“N素不足敏感期”,也是冬小麦抗逆栽培技术中的安全、经济施肥期.     

代料不同配方培养基对木耳菌丝体生长影响的研究

通过代料不同配方培养基对木耳菌丝体生长影响的研究,明确配方1培养基上木耳菌丝体生长较快,菌丝体浓白、稠密、生长茁壮,栽培袋污染率低.这是由于配方1的营养、碳氮比和物理性状适于木耳菌丝体生长的缘故.配方1的成份为:棉子皮48%,锯末48%,石膏1%,磷肥1%,石灰1.5%,尿素0.5%.     

施氮量与花期水分胁迫对不同氮效率油菜产量性能及氮肥利用效率的影响

为了明确花期水分胁迫下施氮对油菜产量形成、产量性能及氮肥利用效率的影响,以2个氮高效基因型(Monty和湘油15)和2个氮低效基因型(R210和Bin270)为供试材料,在不同氮水平(低氮0.05 g/kg,中氮0.2 g/kg,高氮0.4 g/kg),研究了花期水分胁迫下氮肥对不同氮效率基因型油菜产量、产量性能及氮肥利用效率的影响。结果表明,水分胁迫明显抑制了油菜的产量、产量性能和氮素吸收利用能力;就不同施氮量看,少量或过量施氮影响油菜产量及产量性能,所有供试材料的单株角果数、干物质量、收获指数和产量在中氮(0.2 g/kg)处理效果表现最好;水分对油菜生长发育的影响大于氮素养分,氮高效基因型对水分胁迫具有一定的减缓作用;适量供氮能够减轻水分胁迫对油菜生长发育的影响,氮高效基因型较氮低效基因型对水分和氮素胁迫具有更强的适应性。