Abstract A creep test performed on a Landes salt sample during one year and a half is described. During the first year, a 0.6 MPa axial load is applied to the sample. At the end of this one-year phase, strain rate ( 9 × 10 − 12 s - 1 ) is much faster than the strain rate extrapolated from high-stress tests. Steady state strain rate is not reached. In an attempt to reach steady state strain rate “from below”, a 0.9 MPa load is applied during two days before restoring the initial load (0.6 MPa). After the load is restored, reverse creep is observed first (strain rate sign changes before vanishing to zero after a few hours). Then, strain rate increases to reach 5 × 10 − 12 s - 1 after five months, slower than the strain rate before the load change. Commonly accepted constitutive laws can explain this effect, which provides a lower and an upper bound for steady state strain rate. This note presents a method to determine such bounds.

中文翻译：

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确定盐样品蠕变试验期间稳态应变率的上限和下限

摘要 描述了在一年半期间对 Landes 盐样品进行的蠕变试验。在第一年，对样品施加 0.6 MPa 的轴向载荷。在这个一年阶段结束时，应变率 (9 × 10 − 12 s - 1 ) 比从高应力测试推断的应变率快得多。未达到稳态应变率。为了“从下方”达到稳态应变率，在恢复初始载荷 (0.6 MPa) 之前的两天内施加了 0.9 MPa 的载荷。负载恢复后，首先观察到反向蠕变（应变率符号在几小时后消失为零之前发生变化）。然后，五个月后应变速率增加到 5 × 10 − 12 s - 1，比负载变化前的应变速率慢。普遍接受的构成法可以解释这种效果，它提供了稳态应变率的下限和上限。本笔记提供了一种确定此类界限的方法。