【作者】 路亚妮；

【导师】 李新平；

【作者基本信息】 武汉理工大学 ， 桥梁与隧道工程， 2013， 博士

【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。更多还原

【Abstract】 It always induces geological disasters such as frost heaving and thawing settlement, mud-rock flows, landslide, collapse and so on by repeated freeze-thaw effect in the cold region. The joint fractured rock mass is a kind of complicated medium which exist everywhere in rock engineering, for example, dam foundation, slope and underground cavern, due to repeated freeze-thaw, its strength becomes damaged and weaken, and growing deformation in the rock mass. These problems will directly affect the design and construction of rock engineering and normal operation after the engineering was finished. As the rise of engineering construction in western cold region, a number of freeze-thaw problems of geotechnical are urgent to be solved. The paper closely research on damage mechanics of joint fractured rock mass under freeze-thaw condition, we prefabricated fissure in model material to simulate jointed rock mass, then freeze-thaw cycling test and uniaxial and triaxial compression test were conducted of fracture rock samples, freeze-thaw damage mechanics characteristics of fractured rock mass was discussed, and revealed the evolution process of crack initiation, crack propagation and failure of rock mass, damage evolution equation and the constitutive relation under the effect of freezing and thawing and load coupling of freeze-thaw fractured rock mass were established. the main research contents and results are as follows:(1) According to the similarity theory, combined with the rock’s mechanics properties of the scene, the similar modeling material similar to rock-cement silica fume mortar was prepared successful; the method of prefabricating crack in the modeling material was used to simulate the jointed rock mass, ten kinds of integrated rock specimens and fractured rock samples with different geometric characteristics were made totally.(2) The freeze-thaw tests of different freeze-thaw cycles and uniaxial compression test on the prefabricated fractured rock samples were carried out, then analyzed the fracture geometry parameters (crack length, crack dip, the number of cracks) on the effects of the mechanical properties of the freeze-thaw fractured rock, and discussed the failure mechanism of the freeze-thaw fractured rock samples; the paper also summarized the three damage modes of the fractured rock:particles shattered mode, crack mode and fracture along the prefabricated crack mode.(3) The affecting factors of freeze-thaw damage were divided into external factors, internal factors and other factors. Based on mesoscopic damage theory and macroscopic statistical damage model, the freeze and thaw damage evolution, the external load damage evolution and the freeze-load coupling damage evolution were developed. The damage evolutions aim at researching the damage mechanism of jointed rock mass under the load condition of freeze-thaw and external load, then building damage constitutive models of rock.(4) Triaxial compression test was carried out of rock specimens, by this way, the mechanical character with different confining pressure, the influence law of fracture spacing with different freeze-thaw cycles, different confining pressure was analyzed.(5) Based on the theory of the damage fracture mechanics, new computing formulas about the crack condition, extending direction and the length of the wing crack are deduced. Analyze the three different fracture penetration modes of stretch-draw, shear and tensile-shear. Take the initial damage caused by native fissure and freeze thawing and the additional damage caused by crack growth of fractured rock mass into consideration, From the view of crack propagation of damage equivalence, Research on the equivalent model of crack extension of the rock mass under freezing and thawing cycle.(6) Combined with the results of rocklike samples under freeze-thaw cycle and mechanical test, the digital simulation has been taken to the typical rock slope of the Tianshan highway. Computes and analyzes the changes of the displacement, the maximum principal stress and the plastic zone development of rock slope after several freeze-thaw cycles. Research the impacts on slope stability brought by the changes of the mechanical properties under freeze-thaw cycles. Basic and key technologies of slope protection will be provided for the slope of mountainous area in freezing and thawing cycle conditions.更多还原