Experimental measurements during laboratory tests on salt specimens are important for the design of underground facilities in salt formations. These measurements, especially of the volumetric strain, can be influenced not only by the errors inherent to the experimental work, but also by the material heterogeneity. The natural variability due to the presence of impurities can lead to a non-negligible data scattering in the volumetric strain measurements and therefore raises questions concerning the specimens representativity. In this work, we study the effect of the presence of insoluble materials on the representativity of salt specimens during laboratory tests. An experimental investigation of this matter is delicate due to the shortcomings of laboratory work, thus we suggest a numerical method where salt specimens are modeled as pure halite matrices with insoluble inclusions. The insolubles distribution is described via a leveled Gaussian random field. Instead of using three different constitutive models, we use one law that is flexible enough to be adapted for each material involved (pure halite, inclusions and rock salt) with the adequate choice of parameter set. The modeling approach is presented, compared to the morphological modeling approach, and validated. It is employed to study the natural variability effect on strain measurements and to specify the size requirements to achieve representativity. The study proves that using non-representative specimens can misguide the rock characterization process and might even lead to optimistic design criteria. We propose a methodology that combines numerical and experimental work to overcome representativity issues.

盐样品实验室测试期间的实验测量对于盐层中地下设施的设计很重要。这些测量，尤其是体积应变的测量，不仅会受到实验工作固有误差的影响，还会受到材料异质性的影响。由于杂质的存在而导致的自然变异会导致体积应变测量中不可忽略的数据散射，因此引发了有关样本代表性的问题。在这项工作中，我们研究了不溶性材料的存在对实验室测试期间盐样品的代表性的影响。由于实验室工作的缺陷，对此事的实验调查是微妙的，因此，我们建议采用一种数值方法，将盐样品模拟为具有不溶性夹杂物的纯岩盐基质。不溶物分布通过平整的高斯随机场描述。而不是使用三种不同的本构模型，我们使用一种法律，该法律足够灵活，适用于涉及的每种材料（纯盐，夹杂物和岩盐），具有足够的参数集。与形态学建模方法相比，提出了建模方法并进行了验证。它用于研究自然变异对应变测量的影响，并指定尺寸要求以实现代表性。该研究证明，使用非代表性的标本可能会误导岩石表征过程，甚至可能导致乐观的设计标准。