不同化学溶液下砂岩Ⅰ型断裂韧度及其强度参数相关性的试验研究

Laboratory Investigation on the Mode-Ⅰ Fracture Toughness and Its Correlation with the Strength Characteristic of Sandstone Immersed in Different Chemical Solutions

论文通过长期浸泡的方法,以陕西铜川新区龙潭水库典型的库岸边坡的砂岩为研究对象,研究了浸泡在不同化学溶液下砂岩的力学特性及其损伤劣化机制,分析了经不同化学溶液腐蚀后试样的物理力学特性随化学腐蚀时间的劣化规律.研究发现:化学腐蚀后砂岩的物理力学特性均发生不同程度的劣化,其随化学腐蚀时间的劣化规律基本一致;但不同化学溶液下试样物理力学特性的劣化程度有所差异,酸性溶液(pH=3.0)加剧了砂岩的劣化程度,中性化学溶液对其损伤劣化程度也有一定的影响,试验初期,强碱性溶液下砂岩的劣化程度最小,但随着化学腐蚀时间的加长,强碱性溶液下的劣化程度逐渐加剧,大于中性溶液下的,但仍小于酸性溶液.化学腐蚀后砂岩试样均呈现出明显的弱化趋势,其断裂韧度KIC、抗压强度和抗拉强度的劣化程度显著,但各力学特征的劣化程度存在明显的差异,其中抗压强度的劣化程度相对减小,而其KIC的劣化程度较大;同时,化学腐蚀后砂岩的断裂韧度与抗拉强度、抗压强度间的一致性比较明显,存在明显线性关系.可以利用不同化学溶液下砂岩的裂纹扩展半径r来间接说明其力学特征发生损伤劣化的程度.

Long-term immersion is adopted to explore the damage deterioration mechanism and mechanical properties of sandstone corroded by different chemical solutions.The variation regularities in physical and mechanical properties are analyzed by using the sandstone sampled from the hydro-fluctuation belt of a typical bank slope in the Shanxi Tongchuan reservoir region as the object of study.Experimental results show significant degrees of degradation in the physical and mechanical properties of sandstone specimens under hydrochemical corrosion;however,these degrees of deterioration are different for the sandstone specimens soaked in different chemical solutions,i.e.,acid solutions（pH=3.0）may aggravate the deterioration of chemical damage in sandstone,and neutral and alkaline chemical solutions also have certain influence on the damage deterioration.At the early stage of the experiment,the damage deterioration is relatively small in strong alkaline solution.However,the degree of chemical damage deterioration in sandstone increases with the chemical corrosion time;that is,the deterioration degree in acid solutions is the greatest,followed by those in neutral,and then in alkaline chemical solutions.The fracture toughness KIC,compressive strength and tensile strength of sandstone specimens subjected to chemical corrosion exhibit significant damage deteriorating trends;however,the degree of damage deterioration varies for different mechanical prosperities;that is,the damage deterioration of fracture toughness KICis the most severe,followed by that of tensile strength,and then that of compressive strength.There is an obvious consistency among the fracture toughness KIC,compression strength and tensile strength of sandstone specimens,which shows a clear linear relationship.The crack propagation radius rcan be used to indicate the degree of damage deterioration in mechanical prosperities of sandstone immersed in different chemical solutions.The research results have certain reference value for the stability analysis of the hydro-fluctuation belt of a typical bank slope.