论文标题
实验性P-波断层扫描和微观结构的地壳岩石中的实验准静态和动态破裂期间和之后的ORVEART损伤表征
Off-fault damage characterisation during and after experimental quasi-static and dynamic rupture in crustal rock from laboratory P-wave tomography and microstructures
论文作者
论文摘要
岩石中剪切失败期间释放的弹性应变能部分用作断裂能$γ$的弹性能量，以进一步传播破裂。 $γ$在破裂的尖端过程区域内消失，其中包括耗散的能量，以损坏，$γ_\ mathrm {off} $。量化破裂期间形成的OFF损害对于了解其对破裂动力学和破裂尖端背后的滑动过程的影响至关重要，及其对地震辐射的贡献。在这里，我们量化了$γ_\ mathrm {off} $，以及在准静态和动态破裂期间和之后的off毛机械属性的相关更改。我们通过在三轴条件下对完整的Lanhélin花岗岩进行动态和准静态剪切衰竭实验来做到这一点。我们量化了在失败期间和失败后获得的时间分辨的3D $ p $ - 波速度断层扫描中弹性模量围绕故障的变化。我们测量故障后的off毛微骨折损伤。从断层扫描中，我们观察到$ p $ - 波速度的局部最大25 \％下降，用于准静态和动态故障的剪切故障接口。微裂纹密度数据显示，在准静态故障后，损伤区的宽度约为10 mm，动态故障后20毫米。使用有效的培养基方法从$ p $ - 波速度断层扫描模型获得的微裂纹密度与测量的off毛微裂缝损伤非常吻合。 $γ_\ Mathrm {off} $从OFFEALT微裂纹测量值大约为Quasi static破裂的3 kJm $^{2} $，对于动态破裂而言，$γ_我们认为破裂速度决定了滑到几毫米的损伤区域宽度，而剪切断裂能$γ$随着破裂速度的增加而增加。
Elastic strain energy released during shear failure in rock is partially spent as fracture energy $Γ$ to propagate the rupture further. $Γ$ is dissipated within the rupture tip process zone, and includes energy dissipated as off-fault damage, $Γ_\mathrm{off}$. Quantifying off-fault damage formed during rupture is crucial to understand its effect on rupture dynamics and slip-weakening processes behind the rupture tip, and its contribution to seismic radiation. Here, we quantify $Γ_\mathrm{off}$ and associated change in off-fault mechanical properties during and after quasi-static and dynamic rupture. We do so by performing dynamic and quasi-static shear failure experiments on intact Lanhélin granite under triaxial conditions. We quantify the change in elastic moduli around the fault from time-resolved 3D $P$-wave velocity tomography obtained during and after failure. We measure the off-fault microfracture damage after failure. From the tomography, we observe a localised maximum 25\% drop in $P$-wave velocity around the shear failure interface for both quasi-static and dynamic failure. Microfracture density data reveals a damage zone width of around 10 mm after quasi-static failure, and 20 mm after dynamic failure. Microfracture densities obtained from $P$-wave velocity tomography models using an effective medium approach are in good agreement with the measured off-fault microfracture damage. $Γ_\mathrm{off}$ obtained from off-fault microfracture measurements is around 3 kJm$^{2}$ for quasi-static rupture, and 5.5 kJm$^{2}$ for dynamic rupture. We argue that rupture velocity determines damage zone width for slip up to a few mm, and that shear fracture energy $Γ$ increases with increasing rupture velocity.
