Water is ubiquitous within the pore space of rocks and has been shown to affect their physical and mechanical behaviour. Indeed, water can act on the rock strength via mechanical (i.e., reducing the effective stresses) or chemical effects (e.g., mineral dissolution, mineral alteration, subcritical crack growth, etc.). As rock macroscopic strength is controlled by both fracture toughness and friction at the grain-scale, these parameters should also be affected in presence of water. While some recent studies have measured the effect of water on both fracture toughness and frictional parameters to constrain the water weakening of porous rock compressive strength, the physical parameters, or rock characteristics, that influence this weakening are as of yet unclear. Here, we report a series of laboratory experiments in order to determine the influence of a water-saturated, as opposed to dry, environment on five limestones’ strengths. The uniaxial compressive strength, the mode-I fracture toughness and the static friction parameters are of interest. The experiments show that, for the tested limestones, water-saturated conditions provoke a reduction of the uniaxial compressive strength by up to 53 %. This reduction is accompanied by a reduction of the mode-I fracture toughness by up to 34 % and of the static friction by up to 16 %. Even though the water weakening of the uniaxial compressive strength is not influenced by the sample porosity, the mode-I fracture toughness reduction in the presence of water is accentuated for high-porosity limestones. Additionally, low porosity limestones appear to promote higher static friction reductions in water-saturated environments.

中文翻译：

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水弱化和碳酸盐的压缩脆性强度：断裂韧性和静摩擦的影响

水在岩石的孔隙空间中无处不在，并且已被证明会影响其物理和机械行为。事实上，水可以通过机械效应（即，降低有效应力）或化学效应（例如，矿物溶解、矿物蚀变、亚临界裂纹扩展等）作用于岩石强度。由于岩石的宏观强度是由断裂韧性和颗粒尺度的摩擦力控制的，因此这些参数在有水的情况下也会受到影响。虽然最近的一些研究测量了水对断裂韧性和摩擦参数的影响，以限制多孔岩石抗压强度的水弱化，但影响这种弱化的物理参数或岩石特征尚不清楚。在这里，我们报告了一系列实验室实验，以确定水饱和环境（而不是干燥环境）对五种石灰石强度的影响。单轴抗压强度、I 型断裂韧性和静摩擦参数值得关注。实验表明，对于测试的石灰石来说，水饱和条件会导致单轴抗压强度降低高达 53%。这种降低伴随着 I 型断裂韧性降低高达 34%，静摩擦降低高达 16%。尽管水对单轴抗压强度的削弱不受样品孔隙率的影响，但对于高孔隙率石灰岩，在水存在下，I 型断裂韧性的降低会加剧。此外，低孔隙率石灰石似乎可以在水饱和环境中促进更高的静摩擦减少。