Near-surface temperature cycling of stone and its implications for scales of surface deterioration
Near-surface temperature cycling of stone and its implications for scales of surface deterioration
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DOI：
10.1016/j.geomorph.2010.10.005
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发表时间：
2011-07-01
期刊：
影响因子：
3.9
通讯作者：
Viles, H. A.
中科院分区：
文献类型：
--
作者：
Smith, B. J.;Srinivasan, S.;Viles, H. A.
许多先前对石头内部温度梯度的研究都假设地下温度会平滑地、指数地增加和减少，例如，对加热和冷却的日模式做出反应，这些已经被用来解释大规模等高线缩放等现象。在这项高分辨率的实验研究中，多孔石灰岩块使用红外灯进行交替的表面加热和冷却，结果表明，响应短期环境循环（以分钟为单位测量）的内部温度梯度实际上可能是复杂和不一致的。结果证实了在暴露的石头外部10毫米或更小的范围内非常陡峭的温度/应力梯度的重要性。在此之下，数据显示温度反转的复杂模式，其振幅随深度而衰减，其强度和位置受到加热和冷却阶段相对持续时间变化的影响。有人认为，这种倒转可能代表了传入和传出热波之间的“干涉模式”，但无论它们的来源如何，它们都具有潜在的重要性，因为它们发生在许多石头衰变过程，特别是盐风化作用发生的区域内。这些过程总是对温度和湿度的波动作出反应，例如，日晒的短期中断可能在一天内多次触发这些波动。特别是，逆转发生的规模与多次剥落的衰变相当，可能表明对这种以前很少研究的风化模式有潜在的控制。然而，在本出版物的背景下，从这项研究中吸取的主要教训是，不同的行为尺度需要不同的调查尺度。(C) 2010 Elsevier B.V.版权所有
Many previous studies into internal temperature gradients within stone have assumed smooth, exponential increases and decreases in sub-surface temperatures in response, for example, to diurnal patterns of heating and cooling and these have been used to explain phenomena such as large-scale contour scaling. This high-resolution experimental study, in which a porous limestone block was subjected to alternate surface heating and cooling using an infrared lamp, demonstrates that internal temperature gradients in response to short-term environmental cycles (measured in minutes) can in fact be complex and inconsistent. Results confirm the significance of very steep temperature/stress gradients within the outer 10 mm or less of exposed stone. Below this the data indicate complex patterns of temperature reversals, the amplitudes of which are attenuated with depth and which are influenced in their intensity and location by variations in the relative duration of heating and cooling phases. It is suggested that the reversals might represent 'interference patterns' between incoming and outgoing thermal waves, but whatever their origin they are potentially important because they occur within the zone in which many stone decay processes, especially salt weathering, operate. These processes invariably respond to temperature and moisture fluctuations, and short-term interruptions to insolation could, for example, trigger these fluctuations on numerous occasions over a day. In particular, the reversals occur at a scale that is commensurate with decay by multiple flaking and could indicate an underlying control on this previously little-researched pattern of weathering. In the context of this publication, however, the main lesson to be learned from this study is that differing scales of behaviour require different scales of enquiry. (C) 2010 Elsevier B.V. All rights reserved.