水化学环境对砂岩断裂韧度影响的试验研究

发布时间：2018-04-08 16:42

本文选题：断裂韧度　切入点：化学损伤　出处：《重庆大学》2015年硕士论文

【摘要】：岩石是天然形成的材料,是赋存于自然界中非常复杂的介质。它是由颗粒或晶体通过各种作用相互胶结在一起而形成的集合体,不同于一般的工程材料。由于岩石的形成过程比较特殊,使得在岩石的内部构造中存在着初始微裂纹和缺陷。然而,岩石所处的环境经常与水溶液打交道,并且随着国家各种工业的飞速发展,土壤环境中的水、地下水以及江河湖水等都受到不同程度的污染,使得水溶液呈现出不同的酸碱度,因此,水溶液会通过岩石初始微裂纹和缺陷侵蚀岩石,导致岩石的力学性质受到影响,岩石的抗拉、抗压强度及其断裂韧度等力学参数都会受到其所处环境的影响。本文主要针对砂岩断裂韧度化学损伤展开的相关试验研究,分别从宏观上浸泡溶液PH值、试样相对质量和孔隙率的变化,以及试样断裂韧度随时间和PH值的变化,研究砂岩断裂韧度劣化机理。通过试验和对试验结果的分析,本文主要得到以下成果:①浸泡在水化学溶液中的砂岩,水-岩作用随着时间的推移会发生不同的变化,同时其浸泡溶液PH值、试样相对质量以及孔隙率都会发生变化,并且三者的变化与水-岩作用的变化有着很好的相关性和一致性。②浸泡在水化学溶液中的砂岩,其断裂韧度低于未浸泡的砂岩,表明砂岩断裂韧度受到损伤,并且随着浸泡时间的推移,其断裂韧度越小;浸泡溶液PH值越小,其断裂韧度越小。③比较未浸泡与浸泡后砂岩的破坏过程,可以发现它们的破坏过程有所不同,浸泡后砂岩破坏荷载更小,出现裂纹的时间更早,岩石压密过程变长,破坏的时间变长,呈现出部分的延性,不同于初始状态下的完全脆性破坏。④砂岩断裂韧度存在明显的尺寸效应,试样尺寸越大,其值越大。⑤分析砂岩断裂韧度的劣化规律,分别从时间和PH值两个因素出发,计算其损伤变量,发现其损伤有着明显的规律性。
[Abstract]:Rock is a natural material and a very complex medium that exists in nature.It is a collection of particles or crystals cemented together by various interactions, which is different from general engineering materials.Because of the special formation process of rock, there are initial microcracks and defects in the internal structure of rock.However, the environment in which the rock is located often deals with aqueous solutions, and with the rapid development of various industries in the country, the water in the soil environment, groundwater and rivers and lakes are all polluted to varying degrees.The aqueous solution presents different pH values. Therefore, the aqueous solution will erode the rock through initial microcracks and defects, which will affect the mechanical properties of the rock and the tensile resistance of the rock.The mechanical parameters such as compressive strength and fracture toughness are affected by their environment.This paper mainly focuses on the related experimental research on chemical damage of sandstone fracture toughness. The PH value of solution, the change of sample relative mass and porosity, and the change of specimen fracture toughness with time and PH value, respectively, are studied in macroscopically.The degradation mechanism of sandstone fracture toughness is studied.Through the experiment and the analysis of the test results, this paper mainly obtains the following results: 1. The sandstone immersed in the hydrochemical solution has different changes in water-rock interaction over time, and the PH value of the soaking solution is also obtained.The relative mass and porosity of the samples will change, and there is a good correlation and consistency between the changes of them and the changes of water-rock interaction. The fracture toughness of sandstone immersed in hydrochemical solution is lower than that of unsoaked sandstone.The results show that the fracture toughness of sandstone is damaged, and the fracture toughness of sandstone decreases with the time of immersion, and the lower PH value of soaking solution, the smaller the fracture toughness of sandstone is. 3.It can be found that their failure process is different. After immersion, the failure load of sandstone is smaller, the cracking time is earlier, the compaction process of rock is longer, and the damage time is longer, showing partial ductility.Different from the fracture toughness of completely brittle failure sand under initial condition, there exists obvious size effect. The larger the specimen size, the greater the value of sand fracture toughness deterioration. The degradation law of sandstone fracture toughness is analyzed according to two factors, time and PH, respectively.By calculating the damage variables, it is found that the damage has obvious regularity.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU45

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