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首页> 外文期刊>Earth Surface Processes and Landforms: The journal of the British Geomorphological Research Group >Simulation of moisture content in alpine rockwalls during freeze-thaw events
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Simulation of moisture content in alpine rockwalls during freeze-thaw events

机译：冻融事件中高山岩壁中水分含量的模拟

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摘要

Rock moisture during freeze-thaw events is a key factor for frost weathering. Data on moisture levels of natural rockwalls are scarce and difficult to obtain. To close this gap, we can benefit from the extensive knowledge of moisture-related phenomena in building materials, which is incorporated into simulation software, for example the WUFI (R) package of the Fraunhofer Institute of Building Physics. In this paper we applied and adapted this type of simulation to natural rockwalls to gain new insights on which moisture-related weathering mechanisms may be important under which conditions. We collected the required input data on physical rock properties and local climate for two study areas in the eastern European Alps with different elevation [Sonnblick, 3106m above sea level (a.s.l.) and Johnsbach, 700ma.s.l.] and different lithologies (gneiss and dolomite, respectively). From this data, moisture profiles with depth and fluctuations in the course of a typical year were calculated. The results were cross-checked with different thermal conditions for frost weathering reported in the literature (volumetric expansion and ice segregation theories). The analyses show that in both study areas the thresholds for frost cracking by volumetric expansion of ice (90% pore saturation, temperature<-1 degrees C) are hardly ever reached (in one year only 0.07% of the time in Johnsbach and 0.4% at Sonnblick, mostly in north-exposed walls). The preconditions for weathering by ice segregation (-3 to -8 degrees C, > 60% saturation) prevail over much longer periods; the time spent within this frost cracking window is also higher for north-facing sites. The influence of current climate warming will reduce effective frost events towards 2100; however the increase of liquid precipitation and rock moisture will promote weathering processes like ice segregation at least at the Sonnblick site. Copyright (c) 2016 John Wiley & Sons, Ltd.
机译：冻融过程中的岩石水分是霜冻风化的关键因素。关于天然岩壁水分含量的数据很少，很难获得。为了缩小这一差距，我们可以受益于建筑材料中与水分有关的现象的广泛知识，该知识已被并入模拟软件，例如弗劳恩霍夫建筑物理研究所的WUFI（R）软件包。在本文中，我们将这种类型的模拟应用于自然岩壁并将其改编，以获取新的见解，以了解与水分相关的风化机制在哪些条件下可能很重要。我们收集了东欧阿尔卑斯山两个海拔不同的研究区域（Sonnblick，海拔3106m（asl）和Johnsbach，700ma.sl）和不同岩性（片麻岩和白云岩，分别）。根据这些数据，计算出典型年份中具有深度和波动的水分分布。对于文献中报道的霜冻风化（体积膨胀和冰分离理论），使用不同的热条件对结果进行了交叉检查。分析表明，在这两个研究区域中，都几乎没有达到因冰的体积膨胀（90％的孔隙饱和度，温度<-1摄氏度）而导致的霜冻开裂的阈值（在约翰斯巴赫中，只有0.07％的时间是0.4％;在Sonnblick，大多在向北暴露的墙壁上）。通过冰隔离（-3至-8摄氏度，饱和度> 60％）进行风化的前提条件要长得多。对于北方地区，在霜冻破裂窗口内花费的时间也更长。当前气候变暖的影响将使有效霜冻事件减少到2100年。然而，液体沉淀物和岩石水分的增加将至少在Sonnblick现场促进风化过程，例如冰分离。版权所有（c）2016 John Wiley＆Sons，Ltd.

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