青岛隆基汇源基坑冻结法支护方案分析

在青岛隆基汇源基坑的支护中,遇到了传统的基坑支护方案难以解决的问题.这种情况下,考虑到了应用冻结法施工的可能,对应用冻结法支护方案进行支护的可行性作了分析,介绍了冻结法的原理、特点,冻结壁的设计、施工工序、主要技术参数等.     

“冰点新闻”与“南周新闻”批评方式比较

《中国青年报》＂冰点＂新闻栏目在李大同主编时期,选择了软新闻报道方式,这种方式本质上是一种抒情性社会批评方式,报道引起读者强烈反响,成绩辉煌。这种新闻选择产生于特定的社会背景,折射出一个时代新闻编辑文化选择的必然性。而南方周末新闻从诞生起就选择了理性批评方式,这种方式既带来了辉煌的成功也经历了坎坷艰辛,折射出一个时代新闻编辑文化选择的困境。近年来,两大媒体编辑不约而同地改变了新闻报道方式,给新闻编辑的文化选择,带来了诸多引人深思的议题。     

斜井施工防治水关键技术应用探讨

本文结合蒙西南地区地质特点与长城五号矿工程实例,探讨了蒙西南地区井筒过含水层的冻结法、注浆法、探水法等防治水关键技术,为西部地区具有相似条件的井筒防治水施工提供了有力的参考依据。     

贵州高原西北部冻雨的时空变化特征

采用Mann-Kendall、Morlet小波分析、合成分析等方法,分析了近48a贵州西北部冻雨日数的时空分布及环流特征。结果表明:贵州西北部冻雨的空间分布差异显著,冻雨日数自东向西逐渐增多,冻雨日数出现频率最多的在威宁,年平均冻雨日数48.1d,冻雨日数出现频率最少的在六枝,年平均日数仅4.8d,贵州西北部冻雨主要出现在12月到翌年2月。近48a来贵州西北部冻雨日数呈下降趋势,年冻雨日数存在3～5a左右的周期,突变分析表明,贵州西北部冻雨日数突变特征明显,突变发生在1989年。冻雨日数偏多和偏少时期,其环流特征存在着显著的差异。     

冷冻技术对休闲油炸豆类食品品质的影响

本课题根据冷冻技术可使食品（原料）体积膨胀和品质变化等特点,研究确定了冷冻技术对大豆等油炸休闲食品品质变化的影响程度,并进行了品质分析。     

Influence of freezing rate on cryo-damage of cementitious material

We report an experimental investigation on the impact of the freezing rate on the cryo-deformation and cryo-damage of cementitious materials. Saturated, dried and air-entrained mortar specimens are subjected to laboratory freeze-thaw cycles under three freezing rates without moisture exchange with the environment. In addition to basic mechanical properties and pore distribution, the measurement is also effectuated for freezing expansion, residual deformation of the specimens in each cycle. From the results it is observed that a high freezing rate does augment the freezing expansion of material while the cryo-damage is more important for a low freezing rate. Accordingly, both the freezing rate and freezing duration should be taken into account for the cyro-damage extent of cementitious materials.     

Theoretical and experimental studies of heat transfer with moving phase-change interface in freezing and thawing of porous potting soil

Soil in a cold region is subject to frequent freezing and thawing cycles. Soil frozen for a prolonged period may cause adverse freeze damage to the plants due to cell dehydration or root cell rupture. It is important to understand the detailed heat transfer behaviors of the freezing and thawing processes to prevent freeze damage, and to devise proper mitigation measures for effective pot planting in cold regions. A theoretical model was developed to analyze the transient moving phase-change interface heat transfer in the freezing and thawing of porous potting soil. The theoretical derivation is based on the assumption that the soil freezes completely at a single temperature. Microscopic poromechanic effects on heat transfer behavior were ignored. The spatial domain of the problem was simplified to a 1 D spherical coordinate system with variation in the radial direction. Green＇s function was applied to solve for the time-dependent body temperature. Experiments were conducted for validation of the theoretical model Reasonable agreement between the theoretical predictions and experimental measurements was obtained. The theoretical model developed can be easily used to determine the sensitivity of various parameters in the freezing/thawing processes, e.g., thermal properties of soil, ambient temperature, and planting pot size.     

冬季咸水结冰灌溉对滨海盐碱地的改良效果研究

冬季利用地下苦咸水(9.59g/L)对滨海盐碱地进行咸水结冰灌溉,灌溉水量为180mm,咸水融化入渗完成后覆以地膜以防止返盐(T),以不灌溉同期覆膜的地块作为对照1(CK1),以不做任何处理的地块作为对照2(CK2)。种植作物为棉花。结果表明,冬季咸水灌溉结冰、春季咸水冰融化入渗后土壤各层次脱盐效果明显。春季咸水冰融水入渗后,T处理0～20cm土壤表层含盐量由灌水前的0.69%降低到0.39%,脱盐效率为43.5%,显著高于CK1和CK2;而CK1和CK2由于受冬季土壤冻融积盐和春季强烈蒸发影响,0～20cm土壤表层出现强烈的积盐,土壤平均含盐量分别从0.63%和0.58%增加到1.44%和1.27%;在棉花播种期,T处理的土壤表层含盐量为0.31%,而CK1和CK2土壤表层含盐量分别为0.65%和0.98%。由于T处理的土壤含盐量低,适于棉花的播种出苗,播种后出苗率达76.8%,最终籽棉产量达3700.17kg/hm2;而CK1和CK2由于土壤含盐量高,几乎没有棉花出苗,最终棉花绝收。     

冷冻浓缩柑桔汁生产中维生素C的损失

通过对杀菌冷冻浓缩柑桔汁主要生产工艺中维生素C的测定,得出榨汁、浓缩、脱气HTST灭菌、贮藏工序中,维生素C损失分别为0.8％、9.0％、2.6％、<1％。     

刘店矿井冻结法凿井关键技术浅析

针对深厚表土层冻结法凿井井壁安全,从冻结压力、提高井壁强度,尤其是高强度高性能混凝土配制等几个方面进行分析研究,对于以后类似地层条件下冻结法凿井井壁设计和施工安全有一定的借鉴和参考作用。