The transmissivity of a fracture can be related to fracture roughness (JRC₀), initial aperture (E₀), effective normal stress (σ'_n), and tensile strength (σ_t) of the intact rock, based on the Barton–Bandis model and their data, and the transmissivity (or E₀) can increase by shear-induced dilation. Previous studies revealed that the transmissivities of fractures in fault zones, detected as flow anomalies (highly transmissive zones) during borehole investigations at six sites, decrease uniformly with an increasing effective mean stress normalized to σ_t. If this uniform change in transmissivity is explained by σ'_n-dependent fracture-normal displacement following the Barton–Bandis model, those transmissivities represent the upper limit of transmissivities of fractures in fault zones that can increase by shear-induced dilation. To verify this possibility, the E₀ of fractures was estimated using those transmissivities, σ_t, and possible JRC₀ and σ'_n. Then, using this estimated E₀, the changes in transmissivity were simulated, varying σ'_n. The results reproduced very well the observed uniform change in transmissivity. The estimated values of E₀ are tens of micrometers to a few millimeters, which can occur by slight shear displacements (e.g., 0.05–2.00 mm) during shear-induced dilation, easily achievable in fault zones. Thus, the requirements for the highest transmissivities are slight shear displacements and no/limited fracture-sealing rather than large shear displacements. Transmissivities in fault zone fractures that have already reached the highest transmissivities do not change significantly by shear displacement, while the transmissivities of fractures sealed by mineral filling can increase by orders of magnitude, as confirmed by recent fault-stimulation-experiments.

基于 Barton-Bandis，裂缝的透射率可能与完整岩石的裂缝粗糙度 ( JRC ₀ )、初始孔径 ( E ₀ )、有效法向应力 ( σ ' _n ) 和抗拉强度 ( σ _t ) 相关模型及其数据，并且透射率（或E ₀）可以通过剪切引起的膨胀增加。先前的研究表明，在六个地点的钻孔调查期间，断层带中裂缝的透射率被检测为流动异常（高透射带），随着归一化为σ _{t 的}有效平均应力的增加而均匀降低. 如果按照 Barton-Bandis 模型，这种透射率的均匀变化可以用σ ' _n依赖的裂缝法向位移来解释，那么这些透射率代表断层带中裂缝的透射率上限，该上限可以通过剪切引起的扩张而增加。为了验证这种可能性，裂缝的E ₀是使用这些透射率σ _t以及可能的JRC ₀和σ ' _{n 来}估计的。然后，使用这个估计的E ₀，模拟透射率的变化，改变σ ' _n. 结果很好地再现了观察到的透射率的均匀变化。E ₀的估计值为几十微米到几毫米，这可以通过剪切引起的扩张过程中的轻微剪切位移（例如，0.05-2.00 毫米）发生，在断层带中很容易实现。因此，对最高透射率的要求是轻微的剪切位移和无/有限的裂缝密封，而不是大的剪切位移。已经达到最高透射率的断层带裂缝中的透射率不会因剪切位移而发生显着变化，而由矿物填充封闭的裂缝的透射率可以增加几个数量级，这已被最近的断层刺激实验所证实。