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高围压条件下岩石破坏特征及强度准则研究

发布时间:2018-06-24 21:16

  本文选题:高围压 + 岩石破坏特征 ; 参考:《武汉科技大学》2015年博士论文


【摘要】:随着地下矿山逐渐进入深部矿产资源开采阶段,高地应力现象日益突出,导致进入深部开采以后岩爆、突水和采场失稳等一系列灾害性事故频发,并且有不断加剧的趋势。同时,强度准则作为岩石工程设计和开挖的重要理论基础和科学依据,高地应力条件下岩石表现出的非线性强度特征已经无法用传统强度准则进行准确描述和表征。针对上述存在的问题,本文通过以武钢程潮铁矿典型的鄂州花岗岩为试验对象,开展了岩石在不同围压条件下的三轴压缩加载破坏试验研究及强度准则理论研究,主要内容和研究成果集中在如下几个方面: (1)高围压条件下岩石破坏特征研究。基于鄂州花岗岩三轴试验结果,发现岩石在高围压下延性破坏的具体表现特征为:偏应力-应变曲线经过线弹性阶段后逐渐平缓,,进入塑性流动状态,在破坏前呈现为一段水平线,而且围压越高该塑性应变越大。同时,发现岩石破坏形式由低围压下的剪切破坏逐渐向高围压下的剪切劈裂复合型破坏转变,其破坏形态由低围压下的单一破坏断面逐渐转变为高围压下的多破坏断面,其破坏断裂角随着围压的增加逐渐减小。并对高围压下岩石三轴强度特征进行了探索,定义了岩石临界状态围压的概念,推导得出:岩石在临界状态围压破坏时,和的差值为常数,该值不会随着围压的增加而变化,岩石的临界断裂角为45°。通过应用鄂州花岗岩三轴试验数据对传统MC强度准则的验证得出:该准则在低围压下具有较好的适用性,但是其不能反映出岩石在高围压下三轴强度随围压增加呈非线性增加的特征; (2)非线性MC强度准则的适用范围及改进研究。研究分析了非线性MC强度准则的适用范围,并对其进行改进,提出I-MC强度准则。通过应用12种岩石三轴试验数据验证表明:I-MC强度准则精度高于非线性MC强度准则,且具有更广的适用范围。并对I-MC强度准则在真三轴压缩条件下的应用进行了初探; (3)适合高围压条件的岩石强度准则研究。提出了岩石双曲线型强度准则,推导做出其在平面上的屈服曲线及其在主应力空间的屈服面。通过12种岩石三轴试验数据验证了双曲线型强度准则具有较好的适用性,并对双曲线型强度准则在真三轴压缩条件下的应用进行了初探; (4)三轴压缩条件下HB强度准则的改进研究。提出了I-HB强度准则,与HB强度准则相比,该准则具有更明显的非线性特征,评估的岩石三轴强度精度也得到大幅度地提高。同时通过应用12种岩石三轴试验数据验证表明:I-HB强度准则的精度高于I-MC强度准则和双曲线型强度准则。并对I-HB强度准则在真三轴压缩条件下的应用进行了初探; (5)几种准则评估岩石三轴强度精度的对比研究。通过将本文提出的3种岩石强度准则与目前岩石力学界认为较好的几种强度准则进行评估岩石三轴强度的精度比较得出:I-MC强度准则、双曲线型强度准则和I-HB强度准则均具有更高的精度,其中以I-HB强度准则评估的岩石三轴强度精度最高。 通过上述研究,揭示了岩石在高围压条件下的破坏特征和三轴强度特征,对传统强度准则进行了改进研究,提出了适合高围压条件的岩石强度准则,旨在为深部岩石工程开挖设计以及为深部岩石力学理论体系发展提供一定的指导和理论参考。
[Abstract]:As the underground mines gradually enter the deep mineral resources exploitation stage , the phenomenon of high geostress is increasingly prominent , which leads to the frequent occurrence of a series of disastrous accidents such as rock burst , water inrush and stope instability after deep mining , and the nonlinear intensity characteristics under high geostress conditions have not been accurately described and characterized by the traditional strength criterion .

Based on the results of three - axis test of granite in Ezhou , the characteristics of ductile failure of rock under high confining pressure are found as follows :


( 2 ) The applicability and improvement of the nonlinear MC strength criterion are studied . The application scope of the nonlinear MC strength criterion is analyzed , and the I - MC strength criterion is proposed . The results show that the accuracy of the I - MC strength criterion is higher than that of the non - linear MC strength criterion , and has a wider application range .


( 3 ) The rock strength criterion for high confining pressure is studied . The strength criterion of rock hyperbolic curve is presented , the yield curve of the rock is deduced and the yield surface in the main stress space is deduced . The two curves strength criterion is proved to have good applicability through 12 kinds of rock triaxial test data , and the application of the double curve strength criterion in true triaxial compression condition is discussed .


( 4 ) Improved research on the HB strength criterion under triaxial compression conditions . Compared with the HB strength criterion , this criterion has more obvious non - linear characteristics , and the accuracy of the rock triaxial strength assessment is greatly improved . The results show that the accuracy of the I - HB strength criterion is higher than that of the I - MC strength criterion and the hyperbolic strength criterion .


( 5 ) The accuracy of three - axis strength of rock is evaluated by several criteria : I - MC strength criterion , hyperbolic strength criterion and I - HB strength criterion have higher accuracy .

Through the above research , the damage characteristics and triaxial strength characteristics of rock under high confining pressure are revealed , the traditional strength criterion is improved , and the rock strength criterion suitable for high confining pressure condition is put forward . The purpose of this paper is to provide some guidance and theoretical reference for deep rock engineering excavation design and the development of deep rock mechanics theory system .
【学位授予单位】:武汉科技大学
【学位级别】:博士
【学位授予年份】:2015
【分类号】:TD32

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