【作者】 张敏；

【导师】 孙旭曙；

【作者基本信息】 三峡大学 ， 水利工程， 2024， 硕士

【摘要】 湿胀干缩是膨胀性岩土的三大基本工程特性之一,由于天然状态下膨胀性岩土通常处于非饱和状态,所以当膨胀性岩土周围的外界环境发生变化,尤其是水环境发生变化时,将会使其产生极为显著的吸湿膨胀变形,与此同时,这种湿胀过程中常常伴随着剧烈地强度变化而引起的结构变形与破坏现象。但是影响膨胀岩湿胀变形的因素很多而且非常复杂,而且囿于试验条件和认知水平的局限性,使得目前国内外许多研究人员通常都只能够选取其中的一小部分影响因素来对膨胀岩的湿胀变形规律进行研究。笔者在研究过程中发现,有无侧限条件、不同试样高度与不同吸湿深度亦是影响膨胀岩吸湿膨胀变形呈现不同变化规律的重要因素。因此,本文以巴东地区的三叠系红层微膨胀性泥岩为研究对象,采用基础理论、室内试验与数值模拟相结合的研究方法,对膨胀岩的湿胀变形与结构破坏过程进行研究。本文的主要研究工作和成果如下:(1)建立了膨胀岩吸湿-膨胀的简化模型,得到了表征膨胀岩宏观体积变化的吸湿-膨胀公式、表征膨胀岩耦合宏观质量变化与体积变化的吸湿-膨胀公式以及表征膨胀岩耦合宏观膨胀与细观膨胀、质量变化与体积变化的吸湿-膨胀公式。(2)开展了矿物成分检测、直接剪切以及侧限无荷膨胀率试验,得到了巴东组红层微膨胀性泥岩的主要矿物类型与具体含量、抗剪强度参数以及膨胀时程数据。(3)完成了宏细观力学参数与宏细观吸湿-膨胀变形参数的标定工作,建立了与巴东地区红层微膨胀性泥岩室内试样尺寸、物理力学特性以及吸湿膨胀变形特性基本一致的重塑膨胀岩初始模型。(4)在初始模型的基础上,完善得到了有无侧限条件、不同试样高度与不同吸湿深度等三种影响因素下的重塑膨胀岩湿胀模型。(5)得到了吸湿膨胀过程中重塑膨胀岩的膨胀率、膨胀速率、膨胀应力以及裂纹数目随时步的变化规律,以及有无侧限条件、不同试样高度与不同吸湿深度对重塑膨胀岩湿胀变形的影响机制。(6)获取了吸湿膨胀过程中重塑膨胀岩颗粒位移、裂纹扩展随时步的变化云图,得到了细观层面上重塑膨胀岩湿胀变形与结构破坏的演化规律。更多还原

【Abstract】 Wet expansion and dry contraction is one of the three basic engineering characteristics of expansive rock and soil.Since expansive rock and soil are usually in an unsaturated state under natural conditions,when the external environment around the expansive rock and soil changes,especially when the water environment changes,it will produce extremely significant moisture absorption expansion deformation.In the process of wet expansion,the structure deformation and destruction are often accompanied by drastic changes in strength.However,there are many and very complicated factors affecting the wet swelling deformation of expansive rock,and due to the limitations of experimental conditions and cognitive level,many researchers at home and abroad can only select a small part of the influencing factors to study the wet swelling deformation law of expansive rock.In the process of research,the author found that whether there is a lateral limit condition,different sample height and different hygroscopic depth are also important factors affecting the hygroscopic expansion deformation of expanded rock.Therefore,this paper takes the microexpansive mudstone of the Triassic red layer in Badong area as the research object,and adopts the research method combining basic theory,laboratory test and numerical simulation to study the process of wet swelling deformation and structural failure of the expanded rock.The main research work and achievements of this paper are as follows:(1)A simplified model of hygroscopy-expansion of expanded rock was established,and the hygroscopy-expansion formula representing the macroscopic volume change of expanded rock,the hygroscopy-expansion formula representing the coupled macroscopic mass change and volume change of expanded rock,and the hygroscopy-expansion formula representing the coupled macroscopic expansion and mesoscopic expansion,mass change and volume change of expanded rock were obtained.(2)Mineral composition test,direct shear test and lateral loading free expansion rate test were carried out to obtain the main mineral types and specific contents,shear strength parameters and expansion time history data of the red layer microexpansive mudstone in Badong Formation.(3)The calibration work of macro and micro mechanical parameters and macro and micro hygroscopy-expansion deformation parameters was completed,and the initial model of remodeled expansive rock was established,which was basically consistent with the sample size,physical and mechanical properties and hygroscopy-expansion deformation characteristics of the red layer microexpansive mudstone in Badong area.(4)On the basis of the initial model,the wet expansion model of remodeled expanded rock under three influencing factors,such as whether there is a lateral limit condition,different sample height and different hygroscopic depth,was perfected.(5)The changes of the expansion rate,expansion rate,expansion stress and crack number of the remodeled expanded rock with time during the hygroscopic expansion process are obtained,as well as the influence mechanism of whether there is a lateral limit condition,different sample height and different hygroscopic depth on the wet swelling deformation of the remodeled expanded rock.(6)The cloud map of particle displacement and crack growth of reshaped expanded rock during hygroscopic expansion was obtained,and the evolution law of wet expansion deformation and structural failure of reshaped expanded rock was obtained at the mesoscopic level.更多还原