Abstract A series of multi-stage triaxial compression tests revealed quite chaotic reactions of water-saturated Permotriassic sandstones on changing pore water pressures. Not before focussing the various test stages with respect to occurring critical phenomena, which strike the fabric structures due to their fractal nature during any triaxial testing, eventually an approach became tractable: Pore systems with cracks and shear bands can be widened in a quasi-static way, but only up to a stability limit. Thereafter the fabric collapses with a seismogenic contraction of the pore system causing a rise of the pore water pressure. Changes of structural patterns occur as formation either of fissures up to collapse with acoustic emission, or of a rather fractal pattern of crossing shear bands generated without audible noise but with fine grit due to comminution. Dilation and contraction of the pore system are visible from overall volume changes. Both modes of pattern formation can be understood as critical phenomena of the mineral solid. Scale-independent features of these changes of fabric patterns can be transferred to the meso- and macro-scales in the field and in the lithosphere, respectively. However, questions of scale-dependent features related to cohesion should be further investigated.

中文翻译：

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水饱和砂岩多阶段三轴试验中剪切带和裂缝的演化：从分形角度研究微构造

摘要 一系列多级三轴压缩试验揭示了饱和水的二叠纪砂岩对孔隙水压力变化的相当混乱的反应。在关注与发生的临界现象相关的各个测试阶段之前，由于在任何三轴测试期间织物结构的分形性质，这些现象会影响织物结构，最终一种方法变得易于处理：具有裂缝和剪切带的孔隙系统可以在准静态中加宽方式，但只能达到稳定极限。此后，织物随着孔隙系统的地震收缩而坍塌，导致孔隙水压力升高。结构模式的变化发生在裂缝的形成直至伴随声发射的坍塌，或产生的交叉剪切带的分形图案，没有可闻噪音，但由于粉碎而具有细砂。从整体体积变化可以看出孔隙系统的扩张和收缩。两种图案形成模式都可以理解为矿物固体的临界现象。这些织物图案变化的尺度无关特征可以分别转移到现场和岩石圈的中尺度和宏观尺度。然而，与内聚相关的尺度相关特征的问题应该进一步研究。这些织物图案变化的尺度无关特征可以分别转移到现场和岩石圈的中尺度和宏观尺度。然而，与内聚相关的尺度相关特征的问题应该进一步研究。这些织物图案变化的尺度无关特征可以分别转移到现场和岩石圈的中尺度和宏观尺度。然而，与内聚相关的尺度相关特征的问题应该进一步研究。