砂岩在化学腐蚀和冻融循环共同作用下力学特征劣化的试验研究

通过冻融循环试验的方法,研究砂岩在不同化学溶液下经冻融循环后的损伤劣化机制和力学特性,分析了砂岩在不同化学溶液中经历不同冻融循环次数后,单轴压缩和三轴压缩下力学性能的变化规律;初步分析了化学腐蚀和冻融循环共同作用对砂岩的损伤劣化机理;同时,定义了损伤变量来定量分析砂岩的损伤劣化程度。试验结果表明:浸泡在0.1 mol/L(H_2SO_4)、0.1 mol/L(NaOH)和p H=7.0蒸馏水中,随着冻融循环次数的增加,砂岩试样的峰值强度和弹性模量均呈指数函数劣化,而其轴向峰值应变却呈指数函数增加。砂岩的损伤程度随着冻融循环次数的增加而逐渐增大;在H_2SO_4溶液中砂岩的损伤劣化程度大于NaOH和pH=7.0蒸馏水;H_2SO_4溶液加剧了砂岩的冻融损伤劣化,而0.1 mol/L(NaOH)溶液对砂岩试样的冻融损伤劣化却有一定的抑制作用。化学腐蚀和冻融循环共同作用下,水化学溶液虽然在一定程度上缓解冻融循环所引起岩石的损伤劣化,但同时岩石遭受着水化学溶液的腐蚀作用;水化学溶液与冻融循环的共同作用对岩石的损伤劣化是相互促进的,共同影响着砂岩的损伤劣化。

Laboratory investigations on the mechanical properties degradation of sandstone under the combined action between water chemical corrosion and freezing and thawing cycles

The degradation and damage mechanism and mechanical characteristics of sandstone specimens eroded in different chemical solutions under freeze thaw cycle were studied through freeze thaw test method. The variation of mechanical properties of sandstone under uniaxial compression and triaxial compression after being soaked in different chemical solutions under different freeze thaw cycles is analyzed. The damage mechanism of sandstone subjected to coupling effect of chemical corrosion and the freeze-thaw cycle is preliminarily analyzed. At the same time,the damage variable was defined to analyze quantitatively damage degree of sandstone. The test results show that for 0.1mol/L(H₂SO₄),0.1mol/L(NaOH) and pH=7.0 distilled water, with the increase of freeze thaw cycles, the peak strength and elastic modulus of sandstone specimens decrease by exponential function, but the peak axial strain of it increase by exponential function. With the increase of freeze-thaw cycles, the damage of sandstone increases. The degradation and damage of sandstone soaked in H₂SO₄ solution is bigger than that in NaOH solution and pH=7.0 distilled water. H₂SO₄ solution increased the freezing and thawing degradation and damage of sandstone by freeze thaw, but there is a certain inhibition effect on the freezing and thawing damage of sandstone samples soaked in 0.1mol/L (NaOH) solution. Under coupling effect of chemical corrosion and the freeze-thaw cycle,although the chemical solution can relieve the damage caused by freezing and thawing cycles to a certain extent, but also the corrosion of water chemical solution is the same, but meanwhile the chemical damage produced by chemical solution,the coupling effect together with freeze-thaw cycle can give mutual effect on the degradation and damage of sandstone.