裂隙岩体冻融损伤力学特性试验及破坏机制研究

发布时间：2018-04-09 02:41

本文选题：裂隙岩体　切入点：冻融损伤　出处：《武汉理工大学》2013年博士论文

【摘要】：在寒区由于反复的冻融作用而诱发冻胀融沉、泥石流、滑坡、塌陷等一系列的冻融灾害。节理裂隙岩体是坝基、边坡、地下硐室等寒区岩体工程中普遍存在的一类复杂介质,由于反复冻融而引起其强度损伤劣化、变形的不断增大,将直接影响岩体工程的设计与施工,以及投入使用后的正常运营。随着大量兴起的西部寒区工程建设,越来越多的冻融岩土工程问题亟待解决。本文紧密围绕裂隙岩体冻融损伤力学特性以及断裂破坏机理开展研究,采用在模型材料中预制裂隙的方法来模拟节理岩体,通过冻融循环试验和单轴以及三轴压缩试验,探讨裂隙岩体的冻融损伤力学特性,分析在冻融-荷载耦合作用下裂隙岩体中微裂纹的萌生、扩展、搭接、贯通及相互作用的演化过程及力学损伤演化机理,建立裂隙岩体在冻融和荷载耦合作用下的损伤演化方程和本构关系,提出冻融裂隙岩体损伤断裂准则和起裂判据,以新疆天山公路冻融岩质边坡工程为背景,结合试验成果和理论推导进行边坡工程实例的计算分析。本文主要研究研究工作与获得的有益认识如下： (1)根据相似理论,结合现场岩体力学特性,成功配制类岩石相似模型材料-水泥硅粉砂浆材料；采用在模型材料中预制裂隙的方法来模拟节理岩体,共制作完整岩样以及具有不同几何特征的裂隙岩样10种。 (2)对预制裂隙岩样进行不同冻融循环次数的冻融试验和单轴压缩试验,分析裂隙几何参数(裂隙长度、裂隙倾角、裂隙数目)对冻融裂隙岩体力学性能的影响,并对冻融裂隙岩样的破坏机制进行探讨,总结归纳出裂隙岩体的三种损伤模式：颗粒散落模式、龟裂模式和沿预制裂隙断裂模式。 (3)分析裂隙岩体冻融损伤的影响因素,将其分为外因、内因和其它因素；基于细观损伤理论和宏观统计损伤模型,建立了由三部分损伤(冻融引起的损伤、外荷引起的损伤和冻融与荷载耦合作用引起的损伤)引起的冻融裂隙岩体损伤演化方程,探讨在冻融和荷载耦合作用下裂隙岩体的损伤劣化机制,推导出裂隙岩体在经历冻融和荷载双重作用下的损伤本构模型。 (4)通过冻融裂隙试验进行三轴压缩试验,研究经历不同冻融循环次数的裂隙岩样在不同围压下的力学特性,分析不同冻融循环次数,不同围压下裂隙的分布对岩样力学性质的影响规律。 (5)基于损伤断裂力学基本理论,推导出拉剪和压剪复合作用下冻融裂隙岩体裂纹扩展准则,建立在冻胀和围压共同作用下裂纹起裂的条件、扩展方向和扩展长度的计算公式,提出冻融作用下裂隙岩体的应力强度因子。 (6)结合裂隙岩样室内冻融循环试验和力学试验的研究成果,对天山公路一段典型的岩质边坡进行数值模拟计算,分析在经过数次冻融循环次数后,此岩质边坡的位移、最大主应力以及塑性区的发展变化情况,研究裂隙岩质边坡受冻融循环后,其力学性质的改变对边坡稳定性带来的影响,为冻融循环条件下山区边坡防护关键技术的研究提供基础技术支持。
[Abstract]:In the cold due to repeated freezing and thawing caused by frost heaving and thawing, debris flow, landslide, collapse and a series of freeze-thaw disasters. Jointed rock slope, dam foundation is a kind of complex medium, widespread underground chamber and cold in rock engineering, due to repeated freeze-thaw damage and deterioration caused by its strength, constantly the deformation increases, will directly affect the design and construction of rock engineering, and the normal operation is put into use. With the rise of the large engineering construction in cold regions, more and more freeze-thaw geotechnical engineering problems to be solved. This dissertation focuses on the crack of rock freeze-thaw damage mechanics and fracture characteristics research of failure mechanism, using the method of prefabricated fractures in the material model to simulate jointed rock mass, through freeze-thaw test and uniaxial and triaxial compression tests of the three, to investigate the freeze-thaw damage mechanical characteristics of fractured rock mass, analysis in freeze-thaw load Load coupling for fractured rock in the crack initiation, propagation, coalescence and overlapping, interaction mechanism of damage evolution evolution process and mechanics, establishment of fractured rock mass in the freeze-thaw and load coupling damage evolution equation and the constitutive relation, put forward the freeze-thaw damage of fractured rock fracture criterion and crack initiation criterion, to Xinjiang Tianshan Highway freeze-thaw rock slope engineering as the background, analysis and calculation combined with the experimental results and the theoretical derivation of slope engineering examples. The main research work and conclusion including:
(1) according to the similarity theory, combined with the mechanical properties of rock scene, successfully prepared rock similar material cement silica mortar materials; using the method of prefabricated crack in the material model to simulate jointed rock mass, making a total of intact samples and with different geometrical characteristics of the crack rock 10.
(2) on the pre cracked rock in different freeze-thaw test and uniaxial compression test cycles, analysis of geometric parameters of crack (crack length, crack angle, crack number) on the effects of freeze-thaw mechanical characteristics of fractured rock mass, and the failure mechanism of freezing thawing of fractured rock are discussed, the author summed up three damage model of fractured rock mass: particles scattered mode, crack pattern and fracture along the prefabricated crack model.
(3) analysis of fractured rock freeze-thaw damage factors, which can be divided into internal and external factors, other factors; macro meso damage model and statistical damage theory based on the established by the three part damage (freeze-thaw damage caused by external loads, the damage caused by freezing and thawing and load coupling effect caused by injury) the freeze-thaw damage evolution equation of fractured rock mass caused by the deterioration of frozen fractured rock and load coupling damage mechanism, deduces the fractured rock constitutive model after freezing and double effect under load damage.
(4) by freeze-thaw fracture test under three axial compression test, study after different freeze-thaw cycles on the mechanical properties of fractured rock under different confining pressure, analysis of different freeze-thaw cycles, affect the distribution of cracks under different confining pressure on rock mechanical properties.
(5) the basic theory of fracture mechanics based on tensile shear and compressive shear compound under the action of freeze-thaw rock crack propagation criterion is derived based on the frost heave and confining pressure under the action of crack initiation condition, calculation formula of direction and the extended length extension, proposed freezing stress intensity factor of fractured rock mass under the action of freeze-thaw.
(6) combined with the research results of fractured rock indoor freezing and thawing test and mechanical test, numerical simulation of a typical rock slope of Tianshan highway, analysis after several freeze-thaw cycles, the displacement of rock slope, the maximum principal stress and the development of plastic zone, research freeze fractured rock slope and thawing, affect the mechanical properties of the change on slope stability, provide basic technical support for the key technology of freezing and thawing on mountain slope protection under cyclic conditions.

【学位授予单位】：武汉理工大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TU45

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