Experimental determination of constitutive parameters governing creep of rocksalt by pressure solution
Experimental determination of constitutive parameters governing creep of rocksalt by pressure solution
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压溶控制岩盐蠕变本构参数的实验测定
DOI：
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发表时间：
1990
期刊：
影响因子：
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通讯作者：
H. Zwart
中科院分区：
文献类型：
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作者：
C. Spiers;P. Schutjens;R. Brzesowsky;C. Peach;J. L. Liezenberg;H. Zwart
本文研究了多孔集料压实蠕变和密实集料常规蠕变的晶界扩散控制压力解理论模型。在这两种模型中，蠕变的绝对速率由现象学系数Z* = Z 0 exp（−ΔH/RT）确定，这是一个热激活项，表示沿沿着晶界的有效扩散率。为了确定岩盐压溶蠕变的Z 0、ΔH和Z*，对湿颗粒盐进行了压实蠕变实验。选择压实实验，因为理论表明，在这种模式下，压力溶解蠕变加速。在20-90°C的温度和0.5-2.2 MPa的施加应力下，对盐水饱和的NaCl粉末（粒度100-275 μm）进行测试。所获得的力学数据与压实蠕变的理论方程非常吻合。此外，所有样品都表现出良好的压痕，截断和过度生长的微观结构。我们推断，压实确实是通过扩散控制的压力溶液发生的，我们的数据与理论方程的最佳拟合得到Z 0 =（2.79 ± 1.40）× 10−15 m3 s −1，ΔH = 24.53 kJ mol−1。插入这些值到传统的蠕变理论模型的压力溶液导致一个初步的本构关系的压力溶液在重盐。将这种蠕变规律纳入变形图表明，自然界中岩盐的流动往往发生在位错主导和压力溶解场之间的过渡。
Abstract Theoretical models for compaction creep of porous aggregates, and for conventional creep of dense aggregates, by grain boundary diffusion controlled pressure solution are examined. In both models, the absolute rate of creep is determined by the phenomenological coefficient Z* = Z0exp (−ΔH/RT), a thermally activated term representing effective diffusivity along grain boundaries. With the aim of determining Z0, ΔH and hence Z* for pressure solution creep in rocksalt, compaction creep experiments have been performed on wet granular salt. Compaction experiments were chosen since theory indicates that pressure solution creep is accelerated in this mode. The tests were performed on brine-saturated NaCl powder (grainsize 100–275 μm) at temperatures of 20–90°C and applied stresses of 0.5–2.2 MPa. The mechanical data obtained show excellent agreement with the theoretical equation for compaction creep. In addition, all samples exhibited well-developed indentation, truncation and overgrowth microstructures. We infer that compaction did indeed occur by diffusion controlled pressure solution, and best fitting of our data to the theoretical equation yields Z0 = (2.79 ± 1.40) × 10−15 m3s−1, ΔH = 24.53 kJ mol−1. Insertion of these values into the theoretical model for conventional creep by pressure solution leads to a preliminary constitutive law for pressure solution in dense salt. Incorporation of this creep law into a deformation map suggests that flow of rocksalt in nature will tend to occur in the transition between the dislocation-dominated and pressure solution fields.