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31.
含盐量对水泥土强度影响的室内试验研究 总被引:1,自引:0,他引:1
通过含盐量对非有机质土加固强度影响的试验研究,得到了含盐量对水泥土强度的提高或减小的阈值为3.5%。当盐渍土的含盐量低于这个阈值时,盐渍土的加固强度会因可溶性盐的结晶膨胀作用,提高水泥土的强度;相反当盐渍土的含盐量高于该阈值时,盐渍土的强度会因可溶性盐的过多的结晶膨胀作用,使水泥土的结构遭到破坏,从而使水泥土的强度大大降低。同时分析了可溶性硫酸盐、镁盐和氯盐对水泥土的浸蚀性作用,并从盐类对水泥土强度的影响从机理上进行了阐释,提出了高含盐量对水泥土破坏作用的对策。 相似文献
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Metals in contaminated salt marshes are mainly locked in the anaerobic layer of sediments, where they are tightly bound as sulfides and organic complexes. Vascular plants survive in saturated soils in part by pumping O2 into their root zones, changing their microenvironment to an oxic one. This, along with chelating exudates, mobilizes metals, allowing uptake by the roots. We compared the common reed Phragmites australis and cordgrass Spartina alterniflora in lab and field studies for ways in which they handle trace metals. Both plants store most of their metal burden in their roots, but some is transported to aboveground tissues. Spartina leaves contain approximately 2-3 x more Cr, Pb, and Hg than Phragmites leaves, but equivalent Cu and Zn. Furthermore, Spartina leaves have salt glands, so leaf excretion of all metals is twice that of Phragmites. In-depth studies with Hg indicate that Hg excretion correlates with Na release but not with transpiration, which is 2.2 x higher in Phragmites; and that more Hg accumulates in early-appearing leaves than in upper (i.e. later) leaves in both species. Spartina thus makes more metals available to salt marsh ecosystems than Phragmites by direct excretion and via dead leaves which will enter the food web as detritus. 相似文献
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固体传压高温高压岩石三轴实验中,固体传压介质是影响实验结果的重要因素,NaCl介质以它流动性好,围压均匀等特点,八十年代以来越来越受到人们青睐。本文用NaCl介质在〈3GPa固体传压三轴流变仪〉上进行了高温高压岩石流变特性的实验研究,并达到了较高的压力(〉2GPa)和温度(〉1200℃);本文同时利用NaCl介质对样品装样方式及温度、压力等相关测定方面进行了研究。 相似文献
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In this paper, we document the evolution of the emergent Panarea dome in the Aeolian islands (Southern Italy), placing particular emphasis on the reconstruction of the explosive events that occurred during the final stage of its evolution. Two main pyroclastic successions exposing fall deposits with different compositions have been studied into detail: the andesitic Palisi succession and the basaltic Punta Falcone succession. The close-in-time deposition of the two successions, the dispersal area and grain-size distribution of the deposits account for their attribution to vents located in the western sector of the present island and erupting almost contemporaneously. Vents could have been aligned along NNE-trending regional fracture systems controlling the western flank of the dome and possibly its collapse. Laboratory analyses have been devoted to the characterization of the products of the two successions that have been ascribed to vulcanian- and to strombolian-type eruptions respectively. The vulcanian eruption started with a vent-clearing phase that occurred by sudden decompression of a pressurized magma producing ballistic bombs and a surge blast and the development of a vulcanian plume. Vulcanian activity was almost contemporaneous to strombolian-type fall-out eruptions. The coeval occurrence of basaltic and andesitic eruptions from close vents and the presence of magmatic basaltic enclaves in the final dacitic lava lobe of the dome allow us to speculate that the intrusion of a basaltic dyke played a major role in triggering explosive eruptions. The final explosive episodes may have been caused by extensional tectonics fracturing the roof of a zoned shallow magma chamber or by the intrusion of a new basaltic magma into a more acidic and shallow reservoir. Intrusion most likely occurred through the injection of dykes along the western cliff of the present Panarea Island inducing the collapse of the western sector of the dome. 相似文献
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中国的蒸发岩矿床非常丰富,与蒸发岩在成因上密切相关的盐溶角砾岩极其发育。本文简述了中国盐溶角砾岩的分布,总结了盐溶角砾岩的一般特征,划分出盐溶角砾岩的主要类型,探讨了盐溶角砾岩与盐泉的关系。 相似文献