The impact of changes in active‐layer thickness on the depth of pervasive macrofracturing (brecciation) in frost‐susceptible bedrock is unclear but important to understanding its physical properties and geohazard potential. Here we report results from a laboratory experiment to test the hypothesis that active‐layer deepening drives an increase in the depth of brecciation. The experiment simulated active‐layer deepening in 300 mm cubic blocks of limestone (chalk) and sandstone. Temperature, surface heave and strain at depth were measured during 16 freeze–thaw cycles. Macrocracks photographed at intervals were digitally analyzed to visualize crack growth and to quantify crack inclination and length. In chalk, an upper horizon of macrocracks developed first at about 100 mm depth in a shallow active layer during cycles 1–8, followed by a lower horizon at about 175–225 mm depth in a deeper active layer during cycles 9–16. The longest cracks (>35 mm) were most common at inclinations of 0–30° from the horizontal, and numerous cracks

中文翻译：

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模拟活动层加深驱动更深岩石断裂的实验观察

活动层厚度变化对易冻基岩中普遍宏观裂缝（角砾岩化）深度的影响尚不清楚，但对于了解其物理特性和地质灾害潜力很重要。在这里，我们报告了实验室实验的结果，以检验活动层加深驱动角砾岩深度增加的假设。该实验模拟了 300 毫米立方石灰岩（白垩）和砂岩块中的活动层加深。在 16 次冻融循环期间测量了深度的温度、表面升沉和应变。对每隔一段时间拍摄的宏观裂纹进行数字分析，以可视化裂纹扩展并量化裂纹倾斜度和长度。在白垩中，在循环 1-8 期间，在浅层活动层中约 100 毫米深度处首先形成了上层宏观裂缝，在周期 9-16 期间，在更深的活性层中，在约 175-225 毫米深度处出现较低的地平线。最长的裂纹（>35 mm）最常见于与水平方向成 0-30° 的倾斜度，并且裂纹数量众多