岩体断裂与蠕变损伤破坏机理研究

发布时间：2018-02-26 22:37

本文关键词： 裂隙岩体渗透水压判定准则裂隙闭合形态损伤因子蠕变损伤模型时效损伤劣化　出处：《中南大学》2014年博士论文　论文类型：学位论文

【摘要】：岩体中裂隙对其力学特征的影响不可忽略,裂隙岩体在应力场或流固耦合影响下的断裂破坏机制与蠕变损伤机理是岩体力学研究的主要内容之一,对于岩体中工程项目安全顺利、高速有效地开展,具有重要的理论价值和指导意义本文较为系统地开创性研究了应力场和流固耦合影响下裂隙岩体的断裂破坏机制与蠕变损伤机理,以往研究裂隙岩体断裂破坏机制时大多局限于裂隙尖端微裂纹的发育模式与力学机理,而对其强度变化规律较少涉及,因而不可避免了忽视了滑动裂纹模型理论在解释与分析裂隙尖端微裂纹发育模式与力学机理方面的适用范围；同时,对于岩体蠕变损伤机理方面的研究工作,主要集中在非线性组合模型上,而对裂隙岩体蠕变变形的非线性特征并未给予足够的重视,因而常犯线性元件非线性描述的低级错误。本文针对上述实际情形,基于滑动裂纹模型理论解与实测结果之间的差异,首次提出了滑动裂纹模型理论在解释与分析张开裂隙断裂破坏机理方面具有局限性的观点,并结合弹性力学理论,给出了压缩条件下扁椭圆孔边界上环向拉伸应力的解析解；同时,根据流固耦合影响下,裂隙面上的正应力分布特征,创造性地提出了裂隙岩体内高低渗透水压判定准则,并将常见岩土工程问题简化为三种力学模型,在数值领域内分别对其进行了计算和分析工作；另一方面,将损伤因子引入流变学研究工作中,在基本流变元件基础上构建了损伤元件模型,并将裂隙塑性体和加速蠕变体置入组合蠕变损伤模型中,建立了考虑原生节理影响的非线性黏弹塑性蠕变损伤模型。其主要研究成果如下所述： (1)压剪复合应力环境下,由于忽略压应力在裂隙尖端应力场的力学作用,而仅考虑其在裂纹面上产生滑动摩擦阻力的作用效果,并结合最大周向拉应力理论,使得滑动裂纹模型理论很好地解释了压剪复合应力下裂隙尖端翼型张拉裂纹的发育机制。但是研究发现,实测裂隙体强度变化规律与该理论解之间存在显著差异,结合裂隙体形态特征及力学响应规律,首次提出了滑动裂纹模型理论在预测张开裂隙模型破坏机制方面具有局限性的观点,然后根据弹性力学在椭圆孔洞问题上的解析解,给出了单向应力下扁椭圆孔边界上的力学响应规律,解释了张开裂隙试件在单轴压缩实验条件下的变形破坏机理。 (2)在PFC数值计算平台上,基于fish语言改编了白带Fish Tank模型程序,实现了增强Fish Tank模型的开发,然后在程序自带Fish Tank程序和增强Fish Tank程序上分别进行了多裂隙与单裂隙模型的计算和分析工作,并将数值计算结果与实测结果相对比,表明了滑动裂纹模型理论在解释张开裂隙尖端微裂纹发育模式与扩展机制方面局限性的存在。 (3)研究了数值条件下闭合裂隙岩体模型的构建方法与技术,并在PFC2D数值计算平台上完成了闭合裂隙数值模型的单向及双向加载试验研究,通过对比张开裂隙模型的力学响应规律,进一步确认了裂隙闭合形态对其断裂破坏模式影响性的存在。 (4)渗流场中裂隙岩体的力学特性及水岩作用机理是岩石力学领域关注的前沿方向,并逐渐成为理论和实验研究的热门课题；同时,渗流场的存在和改变,也是导致岩体工程失稳,甚至发生大规模地质灾害的重要原因,因此在渗流场中进行卸荷条件下裂隙岩体响应及岩土工程稳定分析,具有广阔的应用前景和学术价值。根据渗流场与应力场耦合作用下裂隙岩体内裂纹面上的应力分布状态,提出了高低渗透水压环境判定准则,并给出了相应渗透水压下的裂隙岩体断裂破坏机理,并将常见岩土工程问题简化为三种力学模型：竖向加载、侧向卸荷与增大渗透压,并完成了相应力学条件下裂隙体模型的计算与分析工作。 (5)蠕变性是深部岩体巷道的典型变形特征,而典型岩样的室内加载试验是研究岩体蠕变变形规律的主要技术方法,基于室内典型岩样的蠕变实验研究深部岩体巷道蠕变变形机制是目前流变学研究热点,并具有重要的工程意义和学术价值。在蠕变模型研究基础上,结合岩石试件的蠕变损伤演化机制,引入损伤力学中的损伤因子来描述由时效损伤劣化效应带来的岩石非线性变形规律,在物理学与流变学上实现真正意义的参数非线性化统一描述,并以此为基础,完成了经典蠕变模型和基本流变元件蠕变损伤变形特征的非线性描述,然后引入裂隙塑性体来描述原生裂隙在蠕变条件下的变形机制,同时引入非线性加速蠕变体,组成考虑原生节理影响的变参数非线性蠕变损伤模型,并给出组合模型相应应力水平下的蠕变状态方程；最后基于东乡铜矿砂质页岩蠕变实验对该蠕变损伤模型进行了验证和分析。
[Abstract]:Influence of rock fracture on the mechanical characteristics of fractured rock mass can not be ignored, the stress field and fracture fluid solid coupling under the influence of the failure mechanism and creep damage mechanism is one of the main contents of the research on rock mechanics, rock mass for the project is safe and smooth, high speed effectively, and has important theoretical value and guiding significance
Study on the stress field and failure mechanism and damage mechanism of creep fracture of fractured rock mass under the effect of fluid solid coupling is systematically created in this paper, previous research of fracture failure mechanism of fractured rock mass is mostly limited to development model and mechanism of crack tip micro cracks, and the strength variation of less involved, thus inevitably neglect the scope of application of the sliding crack model theory in the interpretation and analysis of the crack tip micro crack development model and mechanics mechanism; at the same time, the research work on the creep damage mechanism of rock, mainly concentrated in the non linear combination model, and the nonlinear characteristics of the deformation of fractured rock creep did not give enough attention, so often make nonlinear description the linear element of low-level error. In this paper, according to the actual situation, based on the difference between the sliding crack model theory and measured results, For the first time put forward the sliding crack model theory in the analysis and interpretation of fracture opening fracture failure mechanism of view has its limitation, and combined with the theory of elastic mechanics, the analytical boundary given flat oval ring under compression to tensile stress solution; at the same time, according to the effect of fluid solid coupling, stress distribution is on the cracked surface, creatively put forward the fissure rock high seepage pressure criterion, and the common geotechnical engineering problem is simplified to three kinds of mechanical models, the numerical field has separately carried on the calculation and analysis of the work; on the other hand, the damage factor into the rheological research work, based on the basic rheological element construction the damage component model, and the fracture plastic body and accelerated creep into combined creep damage model was established, considering the nonlinear effects of primary joints visco elastoplastic creep damage model The main research results are as follows:
(1) the compressive shear stress environment, due to the neglect of pressure stress mechanical stress field in the crack tip, and considering only the sliding friction on crack surface effect, combined with the maximum circumferential stress theory, the sliding crack model well explains the shear pressure under combined stress of crack tip airfoil tensile crack development mechanism. But the study found that the law of observation of cracked body strength change and there were significant differences between the theoretical solution, combined with the fracture morphology and mechanical response of the body, are presented for the first time limitation of the sliding crack model cracking model in predicting the failure mechanism of point of view. Then according to the elastic mechanics analysis in elliptic holes on the solution, given the uniaxial stress mechanical boundary flat elliptical holes on response law, explains the cracking of specimen in uniaxial compression tests under the condition of The mechanism of deformation and failure.
(2) in the numerical calculation of PFC platform, fish language adaptation of Fish program based on the Tank model leucorrhea, realizes the development of Fish enhanced Tank model, then with calculation of multi cracks and single fracture model and analysis work of Fish Tank and enhanced Fish Tank program respectively in the program, and the results with the measured by comparing the results of numerical calculation show that the sliding crack model, the crack tip opening theory to explain the micro crack development model and expansion mechanism of limitations.
(3) to study the numerical conditions construction method and technology of closed model of fractured rock mass, and the numerical calculation of PFC2D platform to complete the test of one-way and two-way loading closed fracture numerical model, by comparing the mechanical response of open fracture model, further confirmed the existence of the fracture morphology of the crack closure effect on the model.
(4) the mechanical properties and the mechanism of water rock interaction in the field of seepage in fractured rock is one of the hot topics concerned in the field of rock mechanics, and gradually become a hot topic of theoretical and experimental research; at the same time, the seepage field of existence and change, but also lead to instability of rock engineering, an important reason or even a large scale of geological disasters, so stability analysis of fractured rock mass response and geotechnical engineering under the condition of unloading in seepage field, has broad application prospects and academic value. According to the stress distribution in the crack rock field on seepage field and stress, the level of osmotic pressure environment criterion, and gives the fracture rock mass the corresponding permeability under water pressure and the failure mechanism, and the common geotechnical engineering problem is simplified to three kinds of mechanical models: vertical load, lateral unloading and increase the osmotic pressure, and completed the corresponding mechanical conditions The calculation and analysis of the fractured body model.
(5) the creep of deep rock roadway is the typical deformation characteristics, and the indoor load test is the main method of typical rock deformation law of rock creep, mechanism of typical indoor rock creep experiment of deep rock roadway deformation is currently hot research based on rheology, and has important engineering significance and academic value. On the basis of the creep model, combined with the rock creep damage the evolution mechanism, the introduction of damage factor in damage mechanics is described by the aging damage of rock non-linear degradation law of deformation, describe the parameters in Nonlinear Unified physics and rheology on the real significance of, and on this basis, to complete the description the classical nonlinear creep model and basic rheological element creep damage deformation characteristics, and the introduction of plastic fracture to describe primary fissures in creep conditions The deformation mechanism, while the introduction of nonlinear acceleration creep, nonlinear variable parameter creep damage model considering the influence of the composition of primary joints, and gives the corresponding creep equation of state combination model of stress level; finally, based on the creep test of Dongxiang copper mine of sandy shale to validate and analysis the model of the creep damage.

【学位授予单位】：中南大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TU452

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