The effective stress law at a brittle-plastic transition with a halite gouge layer
The effective stress law at a brittle-plastic transition with a halite gouge layer
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岩盐凿岩层脆塑性转变时的有效应力定律
DOI：
10.1002/2015gl067544
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发表时间：
2016
影响因子：
5.2
通讯作者：
Miki Takahashi
中科院分区：
文献类型：
--
作者：
Hiroyuki Noda;Miki Takahashi
研究了岩盐剪切带脆塑性转变（BPT）附近孔隙压力Pf的影响。我们在温度T ≤ 200°C、围压Pc ≤ 150 MPa和Pf ≤ 140 MPa的气体介质装置上进行的一系列预切摩擦实验表明，即使在Pf升高的情况下，脆性和塑性区域之间的双曲正切关系也能很好地工作，有效应力定律中的Pf系数α为1。与平均应力无关的真实的接触周围的塑性变形导致α= 1，与真实的接触面积比Ar/A无关。随着Ar/A的增大，抗剪强度与有效正应力的函数关系可能偏离线性关系。目前的研究结果支持一个平稳过渡的假设稳定状态的强度分布在BPT周围，提供了新的见解，在地质学上获得的古应力数据在折返糜棱岩剪切带。
We investigated the effect of pore pressurePfnear the brittle‐plastic transition (BPT) for a halite (NaCl) shear zone. Our series of precut friction experiments with a gas‐medium apparatus with temperatureT≤ 200°C, confining gas pressurePc≤ 150 MPa andPf≤ 140 MPa, revealed that a tanh connection between the brittle and plastic regimes works well even at elevatedPf, with a coefficient forPfin an effective stress lawαbeing unity. Plastic deformation around the real contacts independent of the mean stress results inα= 1 regardless of the ratio of the real contact areaAr/A. The functional dependency of the shear strength on the effective normal stress may deviate from a linear dependency with increasingAr/A. The present findings support a smooth transition in a hypothetical steady state strength profile around a BPT, providing new insights in geologically obtained paleostress data in exhumed mylonitic shear zones.