新型耐高温冻胶堵剂的制备与性能评价

针对现今冻胶型堵剂在较高温度和矿化度条件下稳定性较差等缺点,研究出了一种新型冻胶型堵剂,在120℃下,1.5%聚合物A+1.20%交联剂1.20%(C-3)+2.00%缓凝剂(H)+0.02%除氧剂(CY)+0.02%稳定剂(YDC),pH值为9,堵剂初凝时间为7 h,终凝时间为8 h,终凝强度为H~I。新型冻胶型堵剂耐高温、岩性适应能力强、抗盐性和抗剪切能力强,且连续在高温条件下的稳定性、封堵性较好。

东北地区冻融型土壤面源污染的研究

随着我国农业的不断发展,粮食安全战略显得越来越重要,但在农业的发展过程中产生了各种形式的面源污染,给农业生产带来了各种危害,面源污染的面积越来越大。目前,我国对面源污染的治理能力还比较弱,国家对这方面的投入不足,但国家已意识到防治面源污染的重要性。为此,介绍了东北三省的面源污染情况,并分析了面源污染产生的原因并介绍了国内外应对方法,以减少面源污染,为研究东北地区冻融型土壤面源污染控制方法的研究提供参考依据。

新型冻胶型堵剂微冻胶的制备及其评价工艺

详细论述了微冻胶的两种制备工艺:剪切交联和乳液聚合方法,简单介绍了微冻胶的评价方法和评价参数,并提出了建议。

季冻区冻融型黄土滑坡特征及成灾模式分析——以伊犁喀拉吐木苏克滑坡为例

地处天山山脉西段季节性冻土广泛发育的伊犁谷地是我国黄土滑坡灾害严重地区之一,前人在多年冻土区进行了大量冻融模型与冻融灾害机理的研究。伊犁谷地初春气温在-10℃至10℃,季节性冻土区经长期反复冻融循环作用如何使土体强度降低、坡体内水位升高,导致斜坡变形、失稳、破坏,冻土分布范围扩大诱发滑坡等致灾过程研究还需深入。以喀拉吐木苏克滑坡为例,笔者等在以往工程地质勘察工作基础上,分析滑坡形成地质条件、滑坡体形态、结构及危险性,总结出喀拉吐木苏克滑坡变形、失稳、破坏模式为:冻结弱化→冰雪消融、土体蠕变→土体强度劣化、斜坡变形、失稳→强度劣化累积、坡体滑动的过程。与季节性冻土破坏模式相比,本区滑坡致灾因素复杂多样,在冻融循环作用下强度劣化累积效应易被工程人员忽视。

水基冻胶压裂液稠化剂香豆胶的理化性能

香豆胶是国内开发的一种优良的水基冻胶型压裂液稠化剂。本文报导了从不同渠道收集的三家工厂生产的12个样品(11个香豆胶样品,1个改性香豆胶样品)的理化性能测定结果。本项工作表明,香豆胶具有易溶于水、水不溶物含量低、增粘性能良好的特点,作为压裂液稠化剂的综合性能虽不如瓜尔胶,但基本上接近改性瓜尔胶,加之产自国内,价格较低,很有发展前途。

注射用盐酸丁咯地尔冻干工艺的改进

注射用盐酸丁咯地尔为α肾上腺素能受体抑制剂,通过抑制毛细血管前括约肌痉挛而改善大脑及四肢微循环血流。剂型为冻干粉针剂。自投产以来,一直存在着两个问题,一是冻型不好,二是成品水分很难达到要求。本文深入的研究了这两个问题,从注射用盐酸丁咯地尔的冻干工艺出发,进行了冻干工艺的改良和充氮气设备的改进。首先是通过改变冻干曲线及升温方式,解决了冻型不好的问题。其次通过适当延长二次干燥时间及改造了充氮气装置而解决了成品水分难控制的问题。缩短了其它不影响产品质量冻干时间段。在不加大冻干成本的情况下,降低了成品的水分。同时在氮气的粗滤和精滤之间增加了一个干燥器。使氮气进入冻干机之前,除去氮气中所含的水分。经过这两方面的改进,起到了非常明显的作用,基本解决了注射用盐酸丁咯地尔的成品水分难控制的问题。

微冻保鲜法在实船上的应用

“微冻”又称为“部份冻结”或“过冷却”，它是以-4℃～-5℃的工质(空气或盐水)将食品(如鱼)冷却至-3℃，使鱼体内近30％的水份形成冻结，而后贮藏在-3℃的环境中的一种保鲜方法。此法的有效保藏期为一个月以内，较冰鲜(3～5天)为长，较冻结(3～6个月)为短。

Mechanics model and numerical analysis of floor heave in soft rock roadway

The mechanism of floor heave was analyzed by establishing mechanics models and solving differential equations. The amount of floor heave is proportional to the abutment pressure of surrounding rock, roadway width, and the distance of support pressure peak to the roadway and is inversely proportional to the elastic modulus of floor rock. Using FLAC2D to simulate floor rock grouting in soft rock roadway verifies the active role of floor rock grouting in the floor controlling of soft rock roadway; floor rock grouting and grouting range directly impact on the stability scope of surrounding rock, namely, with the increase of grouting range, the subsidence of roof, the approach of both sides, and the amount of floor heave decreased gradually, the stability of surrounding rock is enhanced

Damage mechanism of soil-rock mixture after freeze-thaw cycles

As a widely distributed geological and engineering material,the soil-rock mixture always undergoes frequentative and short-term freeze-thaw cycles in some regions.Its internal structure is destroyed seriously,but the damage mechanism is not clear.Based on the damage factor,the damage research of properties of soil-rock mixture after different times of freeze-thaw cycles is investigated.Firstly,the size-distributed subgrade gravelly soil samples are prepared and undergo different times of freeze-thaw cycles periodically(0,3,6,10),and indoor large-scale triaxial tests are completed.Secondly,the degradation degree of elastic modulus is considered as a damage factor,and applied to macro damage analysis of soil-rock mixture.Finally,the mesoscopic simulation of the experiments is achieved by PFC3D,and the influence on strength between soil-rock particles caused by freeze-thaw cycles is analyzed.The results show that freeze-thaw cycles cause internal damage of samples by weakening the strength between mesoscopic soil-rock particles,and ultimately affect the macro properties.After freeze-thaw cycles,on the macro-scale,elastic modulus and shear strength of soil-rock mixture both decrease,and the decreasing degree is related to the times of cycles with the mathmatical quadratic form;on the meso-scale,freeze-thaw cycles mainly cause the degradation of the strength between soil-rock particles whose properties are different significantly.

Combination effect of seasonal freezing and artificial freezing on frost heave of silty clay

To investigate the frost-heave properties of silty clay under the combination action of seasonal freezing and artificial freezing, and verify the feasibility of combined freezing, eight combined freezing experiments were performed on silty clay with water content (mass fraction) of 23.5% and 28.0%, through developed frost-heave test apparatus, in closed or open system. Two sorts of freezing temperature models, namely, constant and sine models, were applied to artificial freezing. The experimental results indicate that the frost-heave degree in seasonal freezing stage accounts for over 90% of the total in open system and it is up to 95% in closed system; the change of artificial sine-freezing temperature has no influence on the frost-heave degree in closed system, however, slight influence in open system. It is found that the variation of temperature gradient of sine-freezing specimen lags behind that of sine-freezing temperature with half phase; sine-freezing temperature model can reduce frost-heave degree of soil. Brand new technology is proposed for the application of artificial ground freezing and new study field of artificial freezing is created.

适用于裂缝性储层暂堵体系的合成及评价

针对裂缝性储层损害等问题,合成了一种冻胶型暂堵剂,通过对其成胶时间、成胶强度、破胶时间的测定评价其成胶性能,通过填砂管流动实验测定该暂堵剂的阻力系数与残余阻力系数评价其在裂缝性储层中的适应性。试验结果表明,该冻胶型暂堵剂能够在油藏条件下快速成胶,且成胶强度大,能够实现对裂缝的有效封堵,在加入破胶剂后能够快速破胶,且破胶时间可控;在高渗填砂管中拥有良好的阻力与残余阻力建立能力,可以作为调剖堵水剂参与后续提高采收率实验。

Macroscopic Frost Heave Model Based on Segregation Potential Theory

A macroscopic frost heave model with more clear parameters was established. Based on a porosity rate frost heave model and segregation potential theory, a porosity rate function was deduced and introduced into the stress-strain relationship. Numerical simulation was conducted and verified by frost heave tests. Results show that the porosity rate within the frozen fringe is proportional to the square of temperature gradient and current porosity, and is also proportional to the exponential function of applied pressure. The relative errors between the calculated and measured results of frost depth and frost heave are within 3% and 15% respectively, demonstrating that the temperature gradient, applied pressure and current porosity are the main influencing factors, while temperature is just the constraint of frozen fringe. The improved model have meaningful and accessible parameters, which can be used in engineering with good accuracy.

Cultivation Influences on Soil Organic Carbon Associated with Texture in Seasonally Frozen Zones

[Objective] This study aimed to examine indicative roles of texture representing soil organic carbon presence and variability subsequent to cultivation under cold temperate climates with seasonal freeze-thaw events. [Method] Three chronosequences were selected for paired comparisons. Soil samples were collected at six depths with a 10 cm increment. Analysis of variance with general linear model and regression was performed for statistical analysis. [Result] In seasonally frozen soils where fragmentation of macroaggregates was stimulated, soil organic carbon level was positively associated with clay + silt proportion due to a wider textural range, better than sole clay content. Exponential function better fitted the experimental data to present progressively increased effectiveness of clay + silt content in maintaining carbon. Clay content explained 12%-41% and 14%-43% of variation via linear and exponential functions, respectively. Accordingly, clay + silt content explained 47%-65% and 46%-70%. [Conclusion] Texture reflected soil organic carbon occurrence as consequences of reclamation. For seasonally frozen soils with wider textural ranges, it is robust to adapt clay + silt content as dependent variable and exponential function. The generated algorithms provided an available pathway to estimate soil organic carbon losses following cultivation and to evaluate soil fertility.

Research status of soil frost-heave theory and frost-heave prediction models

Soil frost heaving is a complex physical, mechanical, and chemical synthesis process. This paper summarizes the frost-heaving theory over half a century, including the capillary theory, the frozen-fringe theory, and those achievements recently made by scholars. In this paper, we also discus researching achievements of the soil-prediction model during the past 40 years, including the water-dynamics model, the rigid-ice model, the segregation-potential model, and the thermo-dynamic model. This summary and discussion will enable readers to understand the latest direction of research; it also summarizes the development of frost-heave prediction models and their advantages and shortcomings.

Modelling of heat transfer for progressive freeze concentration process by spiral finned crystallizer

This study presents a novel design for a spiral finned crystallizer which is the primary element of progressive freeze concentration(PFC) system, which simplifies the setup of the conventional system. After the crystallizer has been designed, the research experiments have been conducted and evaluated through a thorough analysis of its performance by developing a mathematical model that can be used to predict the productivity of ice crystal at a range of coolant temperature. The model is developed based on the basic heat transfer equation, and by considering the solution's and the coolant's convective heat transfer coefficient(h) under the forced flow condition.The model's accuracy is verified by making comparison between the ice crystal mass' experimental value and the values predicted by the model. Consequently, the study found that the model helps in enhancing the PFC system.

A Mathematical Model for Preeze-Drying

Based on the experiments on freeze-drying carrot and potato slabs, the effects of some parameters, such as heating temperature and pressure on the freeze-drying process are examined. A simple model of freeze-drying is established to predict drying time and the mass variations of materials during the drying. The experimental results agree well with those calculated by the model.

Morphology and survival of cryopreserved-thawed ovarian tissues after heterotopic autotransplantation

Objective： The aim of our study was to observe the survival and morphological changes of thawed ovarian tis- sues after heterotopic transplantation. Methods： Twenty SPF-SD female rats （5-6 weeks old） were equally randomized into the control group and experimental group. In control group, the freshly isolated ovaries were fixed in formalin. In experimental group, the freshly isolated ovaries were vitrified immediately and cut into thin slices. After stored in liquid nitrogen for 21 days, the tissues of experimental group were rapidly thawed and transplanted into back muscles of rats for 2 or 4 weeks, respectively. After that, all rats in experimental group were sacrificed and the ovarian tissues were collected and fixed in 4% formaldehyde solution. Then the ovarian tissues were stained with HE and observed under the light confocal microscope. Re- suits： With the naked eyes, there was no specific alteration except the size reduction with color changing. Under microscopy, we found normal cortex and medulla in the ovary, and the primordial follicles and follicles in various stages were observed in the cortex. The normal oocytes in ovarian tissues of experimental group were significant decreased than in the control group. Conclusion： The ovarian tissues survive well in experimental group and there is no significant difference in the proportion of follicles between different times （2 and 4 weeks） after grafting. Our results suggest that thawed ovarian tissues could survive after heterotopic transplantation into back muscles of rat models and maintain their morphology and function.

Effects of Permafrost Degradation on Soil Hydrological Processes in Alpine Steppe on the Qinghai-Tibet Plateau

Permafrost degradation is prevalent on the Qinghai-Tibet Plateau.This may lead to changes in water and heat transition in soils and thus affect the structure and function of ecosystems.In this paper,using the measured data of alpine steppe in Wudaoliang assessed the model performance in simulating soil freezing and thawing processes.Comparison of the simulated results by simultaneous heat and water(SHAW) model to the measured data showed that SHAW model performed satisfactorily.Based on analyzing the simulated and predicted results,two points were obtained:(1) freezing and thawing of the active layer proceeded both from the soil surface downward.Compared with the freezing process,the thawing process was slower.The freezing period persisted in the surface layer(4 cm depth) for about 5 months;(2) in the next 50 years,frozen period would be shorten about 20 days in the top 100 cm depth while the thawing would start earlier 40 days than present.Soil water storage in the 0-60 cm would decrease by 22% averagely,especially from June to August when the vegetation is at the dominating water consumed stage.Therefore,this kind of permafrost degradation as active layer freezing and thawing processes changes will reduce soil water content and thus influence those ecosystems above it.

How does tree age influence damage and recovery in forests impacted by freezing rain and snow?

The response and recovery mechanisms of forests to damage from freezing rain and snow events are a key topic in forest research and management. However, the relationship between the degree of damage and tree age, i.e., whether seedlings, young trees, or adult trees are most vulnerable, remains unclear and is rarely reported. We investigated the effect of tree age on the degrees of vegetation damage and subsequent recovery in three subtropical forest types-coniferous, mixed, and broad-leaved —in the Tianjing Mountains, South China, after a series of rare icy rain and freezing snow events in 2008. The results showed that damage and recovery rates were both dependent on tree age, with the proportion of damaged vegetation increasing with age(estimated by diameter at breast height, DBH) in all three forest types and gradually plateauing. Significant variation occurred among forest types. Young trees in the coniferous forest were more vulnerable than those in the broad-leaved forest. The type of damage also varied with tree age in different ways in the three forest types. The proportion of young seedlings that were uprooted(the most severe type of damage) was highest in the coniferous forest. In the mixed forest, young trees were significantly more likely to be uprooted than seedlings and adult trees, while in the broad-leaved forest, the proportion of uprooted adult trees was significantly higher than that of seedlings and young trees. There were also differences among forest types in how tree age affected damage recovery. In the coniferous forest, the recovery rate of trees with broken trunks or crowns(DBH > 2.5 cm) increased with tree age. However, in the mixed and broad-leaved forests, no obvious correlation between the recovery rate of trees with broken trunks or crowns and tree age was observed. Trees with severe root damage did not recover; they were uprooted and died. In these forests, vegetation damage and recovery showed tree age dependencies, which varied with tree shape, forest type, and damage type. Understanding this dependency will guide restoration after freezing rain and snow disturbances.