The work of fault growth in laboratory sandbox experiments
The work of fault growth in laboratory sandbox experiments
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DOI：
10.1016/j.epsl.2015.09.046
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发表时间：
2015-12
影响因子：
5.3
通讯作者：
J. Herbert;M. Cooke;P. Souloumiac;E. Madden;Baptiste Mary;B. Maillot
中科院分区：
文献类型：
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作者：
J. Herbert;M. Cooke;P. Souloumiac;E. Madden;Baptiste Mary;B. Maillot
模拟地壳增生的收缩沙箱实验和直剪试验都提供了在粒状材料中产生断层（W prop）所需的工作量的直接数据。与断层相关的力变化的测量揭示了断层增长所消耗的功，这可用于预测断层增长路径和时间。在收缩实验中，早期断层的顺序和类型对于测试的砂包厚度范围（12 至 30 毫米）是一致的。与预期 W 支撑只是一种材料属性相反，实验数据表明，对于相同材料，W 支撑随着砂包厚度的增加而增加。这种正常的应力依赖性源于颗粒材料的摩擦性质。在相同的静摩擦和滑动摩擦值的情况下，由于法向压缩 σ n 的增加，在砂堆中较深处出现的初期断层具有较大的剪切应力降。对于CV32砂，由力降数据计算出的W prop 与σ n 的关系为W prop (J/m 2)= 2.0× 10− 4 (m) σ n (Pa)，与由直剪试验数据计算出的关系为W prop (J/m 2)= 2.4× 10− 4 (m) σ n (Pa) 一致。在收缩沙箱（细沙和玻璃珠）内对不同材料的测试显示了 W 支柱对材料特性的敏感性。在计算模拟实验和地壳断层系统中断层生长消耗的功时，应考虑材料特性和法向应力。
Contractional sandbox experiments that simulate crustal accretion and direct shear tests both provide direct data on the amount of work required to create faults (W prop) in granular materials. Measurements of force changes associated with faulting reveal the work consumed by fault growth, which can be used to predict fault growth path and timing. Within the contractional experiments, the sequence and style of early faulting is consistent for the range of sand pack thicknesses tested, from 12 to 30 mm. Contrary to expectations that W prop is only a material property, the experimental data show that for the same material, W prop increases with sand pack thickness. This normal stress dependence stems from the frictional nature of granular materials. With the same static and sliding friction values, incipient faults initiated deeper in the sand pack have larger shear stress drops, due to increased normal compression, σ n. For CV32 sand, the relationship between W prop and σ n, calculated from the force drop data as W prop (J/m 2)= 2.0× 10− 4 (m) σ n (Pa), is consistent with the relationship calculated from direct shear test data as W prop (J/m 2)= 2.4× 10− 4 (m) σ n (Pa). Testing of different materials within the contractional sandbox (fine sand and glass beads) shows the sensitivity of W prop to material properties. Both material properties and normal stress should be considered in calculations of the work consumed by fault growth in both analog experiments and crustal fault systems.