The Unsaturated Hydraulic Parameters for Aeolian Sand

The water characteristic curve for aeolian sand in two processes of wetting and drying was obtained by the negative water column technique.The values of fitting parameters were calculated according to Van Genuchten formula and the parameters that characterized the prosperities of aeolian sand such as the unsaturated infiltration coefficient and specific water capacity were obtained.The results showed that the water characteristic curve for aeolian sand in wetting process had greater hysteresis quality than ...

Effects of Manufactured-sand on Dry Shrinkage and Crccp of High-strength Concrete

The influences of natural sand, manufactured-sand （MS） and stone-dust （SD） in the manufactured-sand on workability, compressive strength, elastic modulus, drying shrinkage and creep properties of high-strength concrete （HSC） were tested and compared. The results show that the reasonable content （7%-10.5%） of SD in MS will not deteriorate the workability of MS-HSC. It could even improve the workability. Moreover, the compressive strength increases gradually with the increasing SD content,and the MS- HSC with low SD content （smaller than 7%） has the elastic modulus which approaches that of the natural sand HSC, but the elastic modulus reduces when the SD content is high. The influence of the SD content on drying shrinkage performance of MS-HSC is closely related to the hydration age. The shrinkage rate of MS-HSC in the former 7 d age is higher than that of the natural sand HSC, but the difference of the shrinkage rate in the late age is not marked. Meanwhile the shrinkage rate reduces as the fly ash is added; the specific creep and creep coefficient of MS-HSC with 7% SD are close to those of the natural sand HSC.

Influence of temperature on swelling deformation characteristic of compacted GMZ bentonite-sand mixtures

Laboratory swelling deformation tests were carried out on compacted GMZ bentonite and bentonite-sand mixtures with 30%and 50%sand contents at 20,40,60,80 and 90°C with infiltration of distilled water.Influence of temperature,initial dry density,and quartz sand content on the swelling deformation characteristic of compacted bentonite specimens was analyzed.Results indicate that the swelling deformation process is accelerated,and the maximum swelling strain increases with the increase in temperature,while the maximum swelling strain tends to be stable with increasing temperature.In the meantime,the temperature effects depend on both of the sand content and the initial dry density of the specimens,the increases of the maximum swelling strain induced by increasing temperature,are enlarged by increasing sand content or initial dry density.Adding of quartz sand to bentonite not only influences the integrality of bentonite specimen,but also increase the microfissuring in area on quartz sand,which are advantageous to the heat transfer,leading to the increase of swelling deformation capacity of the specimen.The increased dry density relatively increases the bentonite content,so the swelling property is enhanced.However,no change on mineral composition of bentonite was observed when temperature was changed from 20 to 90°C.

Dry reusing and wet reclaiming of used sodium silicate sand

Based on the characteristics of used sodium silicate sand and the different use requirements for recycled sand, "dry reusing and wet reclaiming of used sodium silicate sand" is considered as the most suitable technique for the used sand. When the recycled sand is used as support sand, the used sand is only reused by dry process including breaking, screening, dust-removal, etc., and it is not necessary that the used sand is reclaimed with strongly rubbing and scraping method, but when the recycled sand is used as facing sand (or single sand), the used sand must be reclaimed by wet method for higher removal rate of the residual binders. The characteristics and the properties of the dry reused sand are compared with the wet reclaimed sand after combining the different use requirements of support sand and facing sand (or single sand), and above the most adaptive scheme has also been validated.

Centrifuge tests for seismic response of single pile foundation supported wind turbines in sand influenced by earthquake history

This paper reports on two sets of centrifuge model tests of wind turbines in dry sand and saturated sand subjected to earthquake sequences.The wind turbine system is composed of a single pile foundation and a wind turbine.All tests were applied with liquefaction experiments and analysis projects(LEAP)waves to simplify the analysis.The objectives of the tests are to investigate:(1)the influence of earthquake history on the seismic response of wind turbines;(2)the influence of earthquake history on the dynamic pile-soil interaction;and(3)the influence of two different foundation types on the seismic response of wind turbines.The tests indicated that earthquake history has a significant influence on the natural frequency of the pile and the soil around the pile in the saturated sand,but has no obvious influence on the dry sand.The shear modulus of the soil and the acceleration amplification factor of the pile top in both tests increased and the maximum bending moment envelope of the single pile foundation shrunk.The stiffness of the p-y curve in saturated sand was increased by the earthquake history,while that in dry sand was not significantly affected.

A column study of the hydro-mechanical behavior of mature fine tailings under atmospheric drying

In this paper, the hydro-mechanical behavior and physical properties of mature fine tailings(MFT) under atmospheric drying are investigated through a column study. In the study, evaporation takes place in the development of suction in the upper parts of the column and increasing suction leads to higher strength in the tailings. After 5 days, the suction in the first lift is around 17 k Pa in the upper part of the column.When a second lift is added, the first lift initially loses strength but over a 30 days' period, the strength is recovered to its prior value and suction in the second lift reaches 500 k Pa. The vane shear strength values show a substantial increase in the strength of the MFT after 30 days under atmospheric drying and drainage. The 90% strength found in the column exceeds the threshold(5 k Pa). The hydraulic-mechanical properties of the deposited tailings are closely coupled due to several mechanisms, such as evaporation,drainage, self-consolidation, suction and crack development. The findings of this study will provide a better understanding of the placement behavior of multiple lifts of MFT and thus contribute to reclamation design standards and reduce the use of dedicated disposal areas.

Shrinkage Behaviour of Spheroidal Graphite Cast Iron in Green and Dry Sand Molds for the Benchmarking of Solidification Simulation

The effects of metallurgical and processing parameters on the formation of shrinkage cavities and porosities in spheroidal graphite cast iron have been studied, considering the parameters of carbon equivalent, inoculation, casting modulus, mold type (green or dry) and pouring temperature within specific ranges of these variables. Based on the orthogonal experiments, the metallurgical and processing parameters of the minimum casting shrinkage and the maximum casting shrinkage were obtained, and the effects of metallurgical and processing parameters on the formation of shrinkage cavities and porosities in spheroids graphite cast iron castings were discussed. Finally, two regression equations relating these variables to the formation of shrinkage porosity were derived based upon the orthogonal experiments conducted.

Experimental research on the mixed sand ratio and initial dry density of weathered sand improved expansive soil free load swelling rate

In this paper, through the indoor free load swelling rate test, expansive soil in a section of a first- class highway reconstruction project in Yichang City was studied. It emphatically analyzed the interrelations among free load swelling rate, non-load time, the proportion of mixed sand and initial dry density. Experimen- tal studies have shown that： Free load swelling deformation is mainly divided into three stages of rapid expan- sion, slow expansion and final stability; when the initial dry density is constant, free load swelling rate of the weathered sand modified soil will reduce rapidly before they slow down with the increase of sand proportion, and weathered sand modified soil free load swelling rate is not sensitive to the large amount of sand mixed; in the same mixed sand ratio, weathered sand modified soil free load swelling rate increases rapidly with the in- crease of initial dry density, there is a good linear correlation between them. To take appropriate control of the initial dry density during the expansive soil subgrade construction helps to reduce its swelling deformation and ensures the stability of the embankment.

Establishment and Growth of Potato Micro-Cuttings in Sand Trays

Two separate experiments were conducted to evaluate the success of the establishment and growth of micro-cuttings of potato (5 - 6 cm tall) in sand trays [38 cm (L) × 28 cm (W) × 7.5 cm (H) plastic trays] under controlled environment (22?C ± 2?C, 60 - 75 μmosm–1?s–1 light energy for 16 h daily). In the first experiment, micro-cuttings of potato cv. Diamant were planted at six populations (500, 600, 700, 800, 900 and 1000 cuttings per tray) in treated sand (sun dry, 1% formaldehyde, 0.2% Dithane M-45 and control). The mortality percentage of micro-cuttings was nil for sun dry sand while formaldehyde and dithane M-45 treated sand had 1% - 4% against 15% in the control with the highest population density. Mortality of micro-cuttings in formaldehyde and dithane M-45 treated sand trays were found not to be related to pathogenic organism rather toxic effect of these two chemicals. Micro-cuttings in Sun dry and control treatments showed better growth performance than these in chemically treated sand trays. In the second experiment, urea @ 1, 2 and 3 g per tray was applied as solid form after 15 days of planting the micro-cuttings and as liquid form @ 0.5, 1 and 2% solution sprayed in the micro-cuttings repeatedly after 15, 30, 45 and 60 days of planting. The micro-cuttings which received urea as solid state died within 2 - 3 days and 2% urea solution was also detrimental. Urea solution @ 0.5% found to be very effective for vegetative growth of micro-cuttings in sand trays. The control was also good for vegetative growth but at a slower rate.

Regression Analysis of Ashaka Clay-Bonded Sand

Regression Analysis of Ashaka Clay-Bonded Sand has been successfully carried out. The study data were generated at the National Metallurgical Development Centre, Jos Sand Testing Laboratory. The result of the regression analysis showed that both dry compression strength and dry shear strength have a very strong relationship with clay content and moisture content. The correlation coefficient, coefficient of determination and the coefficient of multiple determination in each relationship was very high. The coefficient of multiple determination for the relationship between dry compression strength, clay content and moisture content was 0.91, while that of dry shear strength, clay and moisture content was 0.97. Two mathematical models have been developed for the estimation of dry compression strength and dry shear strength on the shop floor.

附子无姜不热的成分研究

目的以附子与生姜、干姜、炮姜配伍前后生物碱的变化,探讨附子与干姜配伍的科学意义。方法分别采用溴甲酚绿染色法、异羟肟酸铁染色法测定附子总生物碱、酯型生物碱配伍前后的变化,结合HPLC指纹图谱研究附子与姜类药材配伍前后总体成分变化。结果附子配伍干姜使总生物碱增加,而附子配伍生姜、炮姜使总生物碱减少;附子配伍生姜、干姜、炮姜均使酯型生物碱减少,附子酯型生物碱的量为干姜>生姜>炮姜;从指纹图谱分析可知附子生姜配伍后,附子成分总加权变化率为115.75%,生姜为135.53%;附子干姜配伍后,附子成分总加权变化率为143.48%,干姜为72.09%;附子炮姜配伍后,附子成分总加权变化率为81.00%,炮姜为133.53%。结论附子配伍干姜能促进附子有效成分的溶出,减少附子毒性成分溶出;附子配伍生姜,降低了附子的有效成分和毒性成分,附子配伍炮姜,大幅降低附子有效成分和毒性成分。

磨浆及浆渣分离条件对豆腐皮产率的影响

对影响豆腐皮形成的因素进行探讨,研究传统砂磨与胶体磨、料水比、磨浆次数及细度对出浆率的影响;通过正交试验表明:采用多级分离技术进行连续浆渣分离处理,即第1次采用砂轮磨磨浆,加水量为干大豆重量的4.5倍,浆液通过80目绢布过滤后得所需豆浆,第2次采用胶体磨磨浆,加水量为干大豆重量的3.5倍,随后浆液通过100目绢布过滤后得所需豆浆,能充分提取豆渣中的蛋白质,提高大豆可溶性成分的得率和产品品质,其豆腐皮产率达56.3%。

系统分析方法在大体积换砂垫层施工中的应用

换砂垫层法是地基处理的一种方法,通常用来置换地基承载力较小的局部软弱地基,以提高浅基础下地基的承载力,从而满足强度和变形的要求。但应用大体积的换砂垫层来进行地基处理的施工实例并不多见。原因是影响换砂垫层的效果的因素很多,一旦失控,就可能造成质量事故,危及建筑物的安全使用。本文在系统分析了影响换砂垫层施工质量的各种因素后,结合某住宅基础工程施工实例,介绍了如何对大体积换砂垫层(也称撼砂)施工实行监理,以确保地基处理质量的具体方法和可操作的工作程序。

干姜炮制刍议

[目的]探讨汉州干姜与姜炭的炮制方法。[方法]按照《本草经集注》记载的方法炮制汉州干姜,用不同的切制方法炮制姜炭,比较炮姜、黑姜、姜炭的区别。[结果]汉州生姜两次去皮浸泡后晒干,装瓮缸,通过实践发现并没有发酵现象,而将浸泡后的生姜直接装入瓷罐中可以发酵。姜炭炮制的关键在于干姜的切制,切块是正确的方法,否则无论是清炒、火煨还是研粉,均会导致炮制过度。由于炮制方法的不同,不能简单地以干姜表面的黑褐色作为姜炭的火候标准。古人所谓黑姜,实际上相当于现在的姜炭;而古人所谓里外通黑的姜炭,现代则认为系炮制过度。[结论]姜炭炮制的关键在于干姜切块,黑姜与姜炭是两个不同的炮制品种。汉州干姜的炮制方法,值得进一步研究。

Comparison of seed germination of four Artemisia species (Asteraceae) in northeastern Inner Mongolia,China

Two psammophile-dominated Artemisia semi-shrubs （A. wudanica and A. halodendron） and two annual Artemisia forbs （A. sieversiana and A. scoparia） bear significant ecological functions in Horqin Sandy Land, but systematical information on their achenes＇ germination is very limited. A set of studies were conducted to evaluate seed germination responses to storage periods and methods, different temperatures, lights conditions and sand burial depths, in order to determine inter-specific germination variation in the same genus and to explain how the species adapt to its microhabitat. Fresh achenes of A. wudanica, A. halodendron and A. sieversiana showed high germination capacities, but those of A. scoparia had obvious innate dormancy, which could be broken by chilling and dry storage, especially long-term dry storage. Achene germination of the two semi-shrubs preferred lower temperature fluctuation （10 to 22℃） and was not sensitive to light. But the two annuals preferred higher temperature fluctuation （34 to 22℃） and strong light for their achene germination. These four Artemisia species showed similar responses to sand burial, i.e. soil surface was most favorable for seedling emergence, and the deeper the sand burial, the fewer the seedling emergence. For the two semi-shrubs, their microhabitats are sand dunes with high temperature and intense light, which are not favorable for germination and seedling survival. Only rainfall contributes to temporary decrease of temperature and then triggers germination. We deduced that germination is not the main but a supplementary repro- ductive mode for the two semi-shrubs in sand dunes. For the two annuals, achene germination is the only reproductive mode, but different responses have been developed for microhabitat adaptation. For A. sieversiana, high germination capacities in wide temperature ranges and all light conditions could improve its competition and advancement in the wettest microhabitats. For A. scoparia, obvious innate dormancy of fresh achenes and germination inhabitation under unfavorable conditions are important adaptation to environmental disturbances.

Structures and Properties of Iron Matrix Composites with Tungsten Carbide Particle by EPC-V Process

In this paper the Expendable Pattern Casting with dry sand Vacuum(EPC-V) process is used to manufacture iron matrix composites with tungsten carbide particle.Microstructures of the composites layers were analyzed.The abrasive wear resistance of the composites layers were tested and compared with that of high chromium cast iron.The results show that the iron matrix composites with tungsten carbide particle have high hardness.The abrasive wear resistance of composites with tungsten carbide particle is higher than that of high chromium cast iron.The properties of the matrix materials have been improved remarkably.

利用半干式制砂技术 建绿色环保砂石系统

根据索风营水电站人工砂石骨料系统的设计规模、工艺流程、布置和设备配置,以及高RCC坝对砂细度模数、石粉含量、含水率等指标的特殊要求,针对石灰岩的特性,采用立轴式制砂机“以破代磨”半干式制砂工艺,结合粉砂、水回收利用与环保工程配套,消除粉尘大气污染,人为控制细度模数、石粉含量,分析半干式生产RCC人工砂的控制方法;利用半干式制砂技术建成绿色环保砂石系统。

干法制砂工艺机制砂含水量控制技术研究

目前干法制砂生产工艺中,对机制砂中含水量不可控,存在扬尘和变坨现象,且影响所制备混凝土的品质。本文设计了一种干法制砂工艺机制砂含水量控制技术,通过在生产过程中设置三个数据检测点,分别检测出制砂系统实时的成砂重量、原砂中的含水率和注水流量,来计算出制备合格含水率的成品砂所需的注水量,其中含水量检测采用电容式传感器。文中阐述了设计控制系统组成和设计软件,采用一台工业控制机对产量和含水率进行监测,控制搅拌加湿机水泵的流量,并具备故障报警功能,当设备出现故障时,报警并启动应急措施。通过此控制技术可以有效解决机制砂含水量的控制问题,节约水资源。

快干浇注料在高炉无备用主沟砂口上的应用

改善炉前工作环境 ,提高主沟砂口的使用寿命 ,有利于满足现代大型高炉不断强化冶炼的要求。武钢炼铁厂在无备用主沟砂口情况下开发、应用了快干浇注料 ,并摸索出一套施工新工艺。

Double-Ring Infiltrometer for <i>In-Situ</i>Permeability Determination of Dam Material

Three types of natural soils are studied in this paper: 1) a postglacial silt, 2) a glacial till, and 3) a postglacial sand. The former two are soils from embankment dam sites in Sweden, and the latter is a soil from a natural deposit situated in the Swedish east coastal region. In situ Double-ring infiltrometer (DRI) tests are compared with laboratory constant-head permeability determinations. This study shows that the DRI tests conducted on sandy-silty soils are within sufficient range to the laboratory results, to suggest that in situ near-saturated infiltration capacity may be used as a field estimate of hydraulic conductivity (permeability) for this range of soils. In situ infiltrometer testing may be the better alternative when there is difficulty in achieving representative field conditions in a laboratory setting, e.g., for widely graded soils such as glacial tills.