深基坑锻锤基础冬期施工

在冬期施工，对于土方开挖、钢筋绑扎、人员的通行、砼的浇铸、砼的温度控制，基坑的保温等都带来一定困难，为此提出了深基坑锻锤基础才是最佳实践应用。     

Start-Timing for Calcium Chloride Spray Programs Influences Fruit Calcium and Bitter Pit in ‘Braeburn’ and ‘Honeycrisp’ Apples

Early-season sprays of calcium chloride (CaCl₂) have been reported to sometimes be more effective than later-season sprays for controlling bitter pit in apple (Malus × domestica Borkh.). We conducted a two-year study examining the influence of start-timing of CaCl₂ spray programs on fruit Ca concentrations and at-harvest bitter pit incidence in ‘Braeburn’ and ‘Honeycrisp’ apples in Washington State, USA. Six biweekly sprays of CaCl₂ were applied starting in mid-May (early-start), mid-June (mid-start, the normal commercial start timing), or mid-July (late-start) 2002 and 2003. Although leaf marginal necrosis occurred in all of the CaCl₂-treated plots, no spray damage on fruit was observed. All of the CaCl₂ spray treatments consistently reduced bitter pit incidence relative to the unsprayed control treatment and usually but not always increased the Ca concentration of subdermal cortical tissue at harvest. The early and mid-start spray programs produced lower bitter pit incidence than the late-start program in only one of four situations. Fruit Ca concentrations in the control and early-start spray program did not differ. Fruit Ca concentrations in the mid- and late-start spray programs were not different, and often were higher than that of the early-start spray program. Bitter pit incidence for each cultivar was inversely related to fruit Ca concentration. Substituting cortical Ca/potassium (K) or Ca/magnesium (Mg) concentration ratios for Ca concentration failed to substantially improve and usually degraded the correlations with bitter pit incidence. The results confirm that starting CaCl₂ spray programs in June sometimes is more effective at controlling bitter pit that delaying the start of the spray program until July. The later season sprays tend to be more effective at increasing fruit Ca concentration. There appears to be no detectable advantage for starting spray programs earlier than June. Applying CaCl₂ sprays throughout the growing season, starting sometime in June, appears to be the most economical and effective spray management practice for maximizing fruit Ca and minimizing risk of bitter pit development.     

Diurnal and seasonal water variations of temperature,pH, redox potential and conductivity in gnammas (weathering pits): Implications for chemical weathering

A gnamma or weathering pit is a small-sized cavity sculpted into solid rock which refills with rainwater. This study describes the main hydrological processes in gnammas and the underlying chemical interactions with the environment. Four gnammas developed in a granite tor from central Spain were chosen for monitoring and studying the dynamics of the gnamma–water system. Parameters monitored were air and water temperature, pH, ORP (redox potential), and conductivity. These measurements describe the system dynamics, without the need for special sampling or other potential interferences under low water volumes. Additionally, chemical analyses were carried out to contrast the chemical properties with the chemical composition. As a consequence of water volumes less than 100 L, daily fluctuations tended to cause the largest amplitude changes. Photosynthesis and respiration/putrefaction processes in the gnamma are responsible for daily pH fluctuations up to 4 units, with pH values often greater than 9. ORP generally alternates from positive to negative values as the solution oscillates diurnally between basic and acidic conditions. Conductivity values ∼ 10 μS/cm occur most of the year, with only minor daily oscillations. During dry periods, conductivity increases significantly with maximum values > 400 μS/cm. These high conductivity values reflect atmospheric inputs by summer rainstorms after prolonged dry periods. Therefore, conductivity does not relate directly with chemical species dissolved from the host rock. Silica was the main weathering product of granite dissolution during the year, with highest concentrations (> 200 ppm) in the rainy season. Low Si values measured during the dry season are in accordance with observed precipitation of amorphous silica within the gnamma. Seasonal variations in concentration are also present in Al and Fe as a response to ORP variations and evaporative dynamics, causing mineral dissolution and new mineral precipitation during the year. Relations among the measured parameters are influenced by several factors, including biological processes, temperature effects and water level variations. Factors such as large pH oscillations, basic pH values, acids from biological activity, and alkali cations all increase silicate solubility, thus favoring granite dissolution. Overflow of water during the winter, when the water is chemically enriched, is an effective mechanism to remove weathering products.     

东北管网腐蚀坑焊接补强技术要求

对东北管网钢级为Q345(φ720×8.9mm)的钢管试样进行了管道抢修腐蚀坑补强工艺试验,提出了可焊接的腐蚀坑最大允许深度、补板间最小距离、补板与环焊缝和螺旋焊缝的距离等技术要求。试验结果表明,低流速流体和流体压力对烧穿和硬度影响较小;在立焊位置发生烧穿的可能性比其它位置大,需要严格控制焊接热输入。     

豫西传统地坑窑小气候特征及其热舒适性评价

为探究豫西地区地坑窑的热舒适性及影响成因,在冬季和夏季对河南三门峡市曲村的生土地坑窑进行室内外热环境监测,选取相同位置的地上普通砖房建筑作为对照,利用人体热舒适模型对两者室内外热环境和舒适度进行定量分析、对比与评价。结果表明,冬季地坑窑室内空气温度高于地面普通建筑4.16℃,黑球温度高于地面建筑5.17℃,夏季窑室内平均空气温度低于地面建筑3.1℃,黑球温度低4.06℃;冬夏两季地坑窑室内热舒适均优于地上普通建筑,测量期间夏季和冬季窑室内分别有100%和44%的时间处于舒适范围,地面砖房建筑内分别有22%和11%的时间处于舒适范围,其中,夏季热舒适优于冬季;空气温度是影响窑洞室内热舒适的首要因素,黑球温度是影响室外院落热舒适的首要因素;但冬季窑洞内部保温性能较低,夏季通风不畅,室内湿度高达71.97%,冬季窑洞室内温度是更加急需改善的缺陷。     

泥坑浓香型白酒窖泥中微生物群落结构与多样性分析

本文采用Illumina PE250测序法对浓香型新窖泥、老窖泥和品质较好的老窖泥中微生物群落结构与多样性进行研究。结果表明:从门水平结构分析,厚壁菌门与子囊菌门分别为浓香型白酒窖泥的优势细菌与优势真菌;从属水平结构上分析,新窖泥的优势菌属是乳酸菌属,优势真菌属是单端孢属;老窖泥与品质较好的老窖泥优势菌属是乳酸菌属,优势真菌属是青霉属。不同窖龄、不同质量的窖泥微生物结构多样性具有显著差异。     

深基坑桩锚支护的弹塑性有限元分析

以某高层建筑深基坑桩锚支护为例，采用弹塑性有限元分析，对基坑开挖、支护施工进行了数值模拟，并据此分析了土体的位移和锚杆的受力状态．对比基坑顶部边缘的计算位移与实测位移值，两者较为接近，表明本计算是可行的，可供类似深基坑支护工程借鉴和参考．     

蓄水坑灌单坑土壤氮素迁移转化的数值模拟

为了提高蓄水坑灌条件下土壤氮素的利用率,建立了蓄水单坑土壤氮素迁移转化的数学模型,利用有限体积法进行了求解,并利用室内蓄水单坑灌施尿素条件下土壤水分和氮素运移转化实测数据进行了验证。结果表明,蓄水单坑灌施尿素1 700 mg/L条件下,土壤铵态氮主要分布在20～70 cm深度范围内,1～3 d内土壤铵态氮含量明显增大,7 d后开始减小;土壤硝态氮主要分布在湿润锋附近,1～7 d内硝化作用逐渐增强,20～70 cm范围内硝态氮浓度不断增大。土壤含水率、湿润锋、铵态氮、硝态氮含量计算值与实测值吻合较好,说明所建立的蓄水单坑土壤氮素迁移转化的数学模型是正确的,采用有限体积法求解是可行的。该模型可较好地模拟蓄水坑灌单坑土壤氮素迁移转化的动态变化。     

黄土丘陵沟壑区煤矿沉陷耕地复垦

探索开发适宜黄土地貌和气候特点以及黄土丘陵采煤沉陷损伤规律的土地复垦模式,对于实现该区数量质量并重管理的耕地保护目标具有重要的现实意义。该文基于开采设计、沉降观测参数和MSAS软件,预测山西兴县斜沟煤矿一采区沉陷损毁土地面积为16.54 km2,损毁土地类型以耕地和草地为主,其中轻度破坏耕地面积3.70 km2,中度破坏耕地面积2.41 km2,重度破坏耕地面积0.17 km2。结合黄土丘陵沟壑低潜水位区土地损毁特征和区域生态保育和国土整治目标,拟对轻度破坏的1.65 km2耕地采用裂缝充填和土地平整复垦措施,按照集中连片的原则对轻度、中度和重度破坏的4.63 km2耕地采用坡改梯的土地复垦工程措施进行复垦,实现增加耕地面积0.40 km2,每年减少水土流失4.94万t,提高了耕地质量等级。研究认为,结合企业复垦资金和社会资金投入,按照集中连片的原则对采煤沉陷破坏的耕地采取坡改梯复垦是该区域损毁耕地复垦的有效模式。     

坝上草原鱼鳞坑生态修复措施的水土保持效应

[目的]探究不同位置鱼鳞坑的水土保持效果,确定合理的鱼鳞坑布置原则,为生态脆弱区鱼鳞坑选址与效果评估提供实证研究。[方法]以坝上草原千松坝为研究区,在阴坡、阳坡和河谷分别设置样地,对比鱼鳞坑区和对照区的水土状况,分析不同位置鱼鳞坑对生物量、土壤容重、根系层和土壤养分的影响。[结果](1)阳坡、阴坡、河谷的鱼鳞坑均增加了地上生物量、地下生物量、根系深度、TN含量,DOC等指标,降低了土壤容重。(2)阴坡、阳坡、河谷的鱼鳞坑水土保持效果差异较大;阴坡、阳坡鱼鳞坑均能显著增加植被的根系深度(p<0.05)(阴坡104.19%,阳坡42.87%),而阴坡鱼鳞坑对土壤容重、TN含量、地上生物量的影响更显著(p<0.05)(分别减少9.26%,增加148.05%,增加136.32%);河谷鱼鳞坑能显著增加土壤氨氮和硝态氮(p<0.05)(125.16%,174.53%)。(3)鱼鳞坑位置、修建时间对水土保持指标影响较大,坡位的影响较小;随着鱼鳞坑修建时间的增长,地上地下生物量、TN含量、根系深度增加,土壤氧化还原电位降低。(4)土壤侵蚀严重地区的鱼鳞坑水土保持效果更显著。[结论]...