桥梁钻孔灌注桩施工中若干问题的分析及处理

对逊毕拉河大桥钻孔灌注桩施工中出现的若干问题进行了分析 ,并提出了处理意见     

长江穿越工程施工组织与管理

管道长江穿越工程的共同特点是穿越距离长,管道埋深大,穿越地层多为粉土、粉细砂等软土层(个别地段夹有卵石层).介绍了长江穿越地区工程地质条件、穿越主要技术参数、施工前期的准备、施工过程的组织和管理,穿越工程遇到的困难及决策,为今后同类工程提供了有益的借鉴.     

磷钨酸法测定钻井液材料中有机阳离子的探讨

磷钨酸法是测定两性离子表面活性剂阳离子度的经典方法,经实验验证该方法可用于测定钻井液材料中的阳离子或两性离子的含量。含有有机阳离子基团的钻井液材料由于其成分复杂,试样溶液颜色较深,不易准确测定其中的有机阳离子度。本文采用钠型阳离子交换树脂对产品进行提纯,在弱酸性条件下,以刚果红为指示剂,用磷钨酸标准溶液定量测定有机阳离子度,实验相对误差是0.59%。本文介绍了方法原理、操作程序及方法验证。结果表明,采用磷钨酸法测定钻井液中的有机阳离子含量不受阴离子的干扰,而且无机阳离子对测定结果也无影响。经岩心相对回收率实验,测定结果和使用性能相吻合,结果准确可靠。     

Soil pore-water environment and CO2 emission in a Luvisol as influenced by contrasting tillage

Little is known how contrasting tillage (deep ploughing, top- and sub-soil loosening with straight or bent leg cultivator [BLC], direct drilling [DD]) affect important soil physical properties (total porosity [TP], pore size distribution [PSD], water release characteristics [WRC]) and CO₂ emissions from a Luvisol. The study was aimed to alleviate compaction on land that had been under reduced tillage for 4 successive years. Undisturbed core samples were collected from 5–10, 15–20 and 25–30 cm depths for soil WRCs, TP and pore-size distribution determination. A closed chamber method was used to quantify the CO₂ emissions from the soil. Soil loosening with straight or BLC produced the highest total soil porosity (on average 0.48 m³ m^?3) within 5–30 cm soil layer, while conventional tillage (CT) gave 6%, DD up to 25% reduction. Sub-surface loosening with a BLC was the most effective tool to increase the amount of macro- and mesopores in the top- and sub-soil layers. It produced 21% more macro- and mesopores within 25–30 cm soil layer as compared to the soil loosened with a straight leg cultivator. Plant available water content under CT and DD was lower as compared to that under deep loosening with straight or BLC (23% and 18%, respectively). DD produced 12% lower soil surface net carbon dioxide exchange rate than CT and by 25–28% lower than deep soil loosening with straight or BLC. The increase in micropores within 25–30 cm soil layer caused net carbon dioxide exchange rate reduction. The amount of mesopores within the whole 5–30 cm soil layer acted as a direct dominant factor influencing net CO₂ exchange rate (NCER) (Pxy = ?3.063; r = 0.86).     

Reappraisal of methods of application of nitrogen and phosphorus at sowing on the yield,grain protein content and nitrogen economy of malting barley in Sweden

Abstract

To compare the relative efficiency of different fertilisation strategies, malting barley was fertilised with calcium ammonium nitrate (CAN) or compound ammonium nitrate with phosphorus (NP) applied in two ways: broadcast and harrowed into the seedbed before seeding or banded using the Scandinavian combi-drill design, with the fertiliser between every second seed row, and 40 mm below. A fixed nitrogen level (120 kg N ha^?1) was used, giving four fertiliser treatments. Eleven experiments were carried out the years 1992–1994, with latitudes 55° 55′ N as southern and 59° 36′ N as northern limit. Fertiliser-use efficiency, defined as grain yield, or grain nitrogen yield, per unit of applied N, was strongly affected by the treatments: values for combi-drilled were higher than for broadcast fertiliser and higher for NP than for CAN, with the effects being additive. The best treatment, using both banding and NP, resulted, as a mean of all trials, in a grain yield increase of 939 kg ha^?1 at 15% moisture content, or a nitrogen yield increase of 18 kg nitrogen ha^?1 compared with the poorest, using broadcast CAN. The N combi-drill effect was expected to be dependent on water availability, but this could not be confirmed when accumulated rainfall during crop establishment was used as test variable. The combi-drill effect was strongest in places where major extractable cations were abundant, possible explanations for this are discussed. Application of P to the crop and the use of combi-drill are recommended for malting barley fertilisation in Sweden.     

早稻机械精量穴直播与人工撒播对比研究

为了推广水稻精量穴直播施肥机械化同步技术,以早稻品种湘早籼32号为材料,进行机械精量穴直播和人工撒播大面积对比试验。结果表明,机播稻的分蘖数、株高、最高苗、成穗率、有效穗、每穗粒数和理论产量均显著高于撒播稻(P0.05)。该研究可为水稻机械化精准种植模式与关键技术发展提供参考。     

江西秋芝麻(早稻茬)高产轻简化栽培技术研究

为了探讨江西秋芝麻的高产高效栽培技术,采用随机区组设计,研究了免耕撒播条件下的不同密度以及不同播种方式对芝麻生长发育和产量的影响。结果表明:免耕撒播条件下,以高密度种植(每667m2 30 000株)有利于秋芝麻获得高产,是一种比较可行的方法,同时翻耕条播比其他3种种植方式(免耕撒播、免耕条播、翻耕撒播)的芝麻长势好、产量高。     

绝缘层厚度对孔电解加工稳定性和精度的影响

通过对孔电解加工中加工间隙的电场和流场仿真,研究了电极绝缘层的涂覆尺寸特征对小孔加工性能的影响.进行了管电极电解小孔的试验,得到了理想的绝缘层厚度参数.试验和仿真均表明, 增大绝缘层厚度可以减小孔的侧面腐蚀面,并使孔圆度有所增加,同时提高了加工过程的稳定性,但过大的涂覆厚度易出现打火甚至加工短路.     

玉米流体穴播条件参数试验研究

以土壤含水量、种子浸泡时间、种液用量为试验变量,出苗率为试验指标,对玉米流体穴播条件进行了二次回归正交旋转组合试验。结果表明:土壤含水量、种液用量对出苗率影响显著,随着二者数值的增大种子出苗率提高,但二者的影响是非线性的,在二者数值较大时,对出苗率影响的变化趋势减缓并下降,表明土壤总含水量过高对种子萌发出苗不利;在试验条件下,土壤含水量为7.12%、种液浓度为0.15%时,单位面积种液用量应低于5.6 m3·hm~(-2)。种子浸泡时间对出苗率的影响不显著,但播前浸泡可缩短或略去种子在田间的吸水膨胀过程,使种子萌发出苗早。建立了确保玉米出苗率的种液用量与土壤含水量数学模型,依此模型可根据土壤含水量确定种液施用量。     

稳定泡沫钻井流体抑制性研究

在泥页岩地层进行稳定泡沫钻井施工时,为防止地层坍塌和卡钻,通常在循环流体中要加入抑制剂。对各种类型用于泥浆钻井液的抑制剂进行了试验评价。评选出适合泡沫钻井与发泡剂 FP-2相匹配的抑制剂,在此基础上对泡沫流体的结构、与井壁的相互作用及其抑制性机理进行分析,为今后泡沫钻井流体的抑制剂选择提供了一种思路。