含水软弱夹层非线性流变机理及其工程应用研究

发布时间：2018-06-23 05:34

  本文选题：软弱夹层 + 应变软化　； 参考：《中国地质大学》2017年博士论文

【摘要】：在我国坚持可持续发展和深入实施“西部大开发”的战略决策中,矿产资源的合理开发和利用是非常重要的环节。我国中西部与西南地区湖北、湖南、四川、贵州、广西、云南等省大范围存在含缓倾软弱夹层(岩层和夹层倾角均小于25°)的二叠系石灰岩地层,该地层拥有丰富的优质石灰石矿产资源,是我国大量基础设施建设的重要建材来源。随着开采不断向深部和高处进行,矿山所揭露的地层越来越多,所揭露的地层越来越复杂,面临的矿山水文地质条件也愈加复杂,加剧了对边坡岩体的扰动,导致岩体力学性能劣化。各种软弱地层的暴露、边坡临空面的扩展都严重影响着矿山边坡的稳定性和安全性。软弱夹层由于其自身的特殊性,往往成为矿山边坡的潜在滑动面,对矿山过程边坡和终了边坡的稳定性起着控制作用。同时软弱夹层也是水的良好的渗流通道,水岩作用加剧了夹层本身的力学性能的劣化,使软弱夹层的流变特性愈发明显。因此研究水对软弱夹层的力学参数的劣化规律对矿山边坡稳定性评价和安全施工有至关重要的作用。本论文研究结合国家自然科学基金项目“降雨和爆破反复作用下高边坡缓倾软弱夹层的流变特性及其致滑机理研究”(41672317)和横向项目“峨胜采矿场露采高陡边坡稳定性论证与优化研究”,以四川峨胜矿区所揭露的二叠系茅口组含炭质泥页岩软弱夹层为研究对象,考虑四川峨胜采矿区所处的水文地质环境和气象条件,对其进行不同含水率下常规环剪试验、环剪蠕变试验。基于常规环剪试验结果,探讨了不同含水率下的软弱夹层峰值强度和残余强度的变化规律,进行了将含水率作为损伤变量的软弱夹层力学参数劣化规律分析。开展不同含水率不同法向压力下的环剪蠕变试验,在对环剪蠕变试验结果分析的基础上,基于分数微积分提出了考虑软弱夹层的含水率引起的流变模型参数变化作为损伤变量的非线性粘弹塑性流变本构模型(DNMAP模型)。推导了DNMAP流变模型有限差分格式,采用FLAC3D二次开发平台在Microsoft visual studio2010编程实现了新建本构模型的二次开发,并对其正确性和可行性进行了验证。以二叠系茅口组软弱夹层作为潜在滑动面的“1270-1380m”开挖平台变形体为研究对象,对其进行了渐进性破坏分析及长期稳定性预测,并提出了相应的防治措施。本文取得的研究成果如下:(1)以四川峨胜采矿场“1270-1380m”开挖平台出露的二叠系茅口组含炭质泥页岩软弱夹层为研究对象,在分析其沉积环境和构造环境的基础上,分析了软弱夹层的形成过程。利用矿物鉴定、X射线、激光粒度分布仪等手段对二叠系茅口组软弱夹层的矿物成分、化学成分、粒径组成等特征进行分析,并通过开展一系列物理力学试验获取了软弱夹层的基本物理特性参数。研究表明:二叠系茅口组软弱夹层矿物成分主要以粘土矿物、方解石为主。因粘土矿物的亲水性较强,因此含水率对软弱夹层的力学特性具有显著的影响。(2)对二叠系茅口组软弱夹层开展常规环剪试验,研究了相同干密度不同含水率重塑软弱夹层试样在不同法向应力作用下的剪切变形破坏特征。研究表明:法向应力是影响软弱夹层应变硬化及软化特性的重要因素。随含水率及法向应力的增大,较低法向应力下表现应变软化特性的试样,在环剪试验过程中的法向位移特征表现为由剪胀为主转变为剪缩为主。高法向应力下表现应变硬化特性的试样则表现出速率逐渐趋于稳定的剪胀特性。环剪应变特性受法向压力和含水率的影响,法向压力越大、含水率越高,试样的应变硬化特性越明显。分析了含水率与法向应力对于软弱夹层峰值强度和残余强度的影响规律,试验结果显示软弱夹层试样的峰值剪应力、残余剪应力及其对应的剪切位移均与试样的含水率和法向应力呈正相关关系。基于摩尔-库仑强度准则与损伤力学原理研究了含水率对于软弱夹层等效抗剪强度参数的损伤劣化规律,得到了抗剪强度参数损伤率与含水率的函数关系式。对试样环剪破坏后的环剪面进行微观电镜扫描,讨论了应变软化与应变硬化试样在微观结构上的差异性,并指出环剪试验过程中颗粒位移、破碎与定向排列的差异是影响试样宏观力学特性的重要因素。(3)基于常规环剪试验成果,对二叠系茅口组软弱夹层开展不同含水率、不同法向压力下的环剪蠕变试验。对不同含水率下夹层试样的剪切蠕变变形和应变速率进行了分析。同时通过两种方法确定了不同含水率下软弱夹层的长期强度,并与残余强度进行了对比。通过电镜扫描对不同含水率试样环剪蠕变破坏之后的破坏面进行了微观特性分析。试验结果表明:(1)在低于饱和含水率时,含水率越高,瞬时剪切应变随应力等级的增加而变形增量变大;而高于饱和含水率之后,瞬时剪切应变增量随含水率的增加而呈现出降低的趋势,增量最大值出现在饱和含水率附近。随着含水率的增加,试样累计蠕变增量也呈增大的趋势。从蠕变曲线达到稳态蠕变的变形量与瞬态弹性应变的比值来看,随着环剪应力等级的增加,稳态蠕变的变形量与瞬态弹性应变的比值逐渐增加。应力等级越大,蠕变变形量在总变形中的比重增大,蠕变特性表现得愈发明显。(2)含水率对蠕变变形速率的规律性影响主要体现在对蠕变衰减段持续时间的影响上。研究表明,蠕变衰减持续时间随含水率的改变大致呈线性变化规律。随着应力等级的增加,0.6倍的残余应力作用下拟合直线的斜率大于残余应力的拟合直线斜率。环剪应力水平越高,蠕变衰减持续时间的增长率越缓。(3)等时应力-应变曲线法所确定的长期强度均大于稳态蠕变速率法所确定长期强度,但量值相差不大。通过对不同含水率下夹层的长期强度与含水率的关系进行拟合分析,发现长期强度与含水率呈线性负相关,含水率越高,软弱夹层的长期强度越低。(4)不同含水率试样在蠕变破坏之后的微观特性存在着显著差异,含水率较低的试样,破坏面光滑,变形擦痕较为清晰,片状结构明显;随着含水率的升高,试样逐渐软化,由于试样含有膨胀性的粘土矿物,颗粒由于膨胀性变强排列变得致密,各向同性明显。由于试样破坏前变形量变大,破坏面上多空隙和裂缝出现,表现出延性破坏特征。(4)详细介绍了分数阶微积分的几种常用定义,并基于分数阶微积分对现有的几种常见流变元件模型进行了改进,分别给出了蠕变本构方程。通过对饱和状态下软弱夹层试样蠕变破坏前试验曲线的拟合,综合考虑各种因素选取基于分数阶微积分改进的Maxwell元件模型作为新建蠕变本构模型的粘弹性部分。同时,分析发现非定常参数Abel粘壶能够描述蠕变加速破坏段的特性,因此将其与塑性元件并联组合成粘塑性体与前面改进Maxwell元件模型串联构建了一种新的非线性剪切蠕变本构模型(NMAP),对其蠕变本构方程进行了推导。通过对试样环剪蠕变加速破坏段的拟合发现,新建立的NMAP元件本构模型能够很好地拟合蠕变全过程试验曲线。(5)基于损伤理论将软弱夹层的含水率引起的流变模型参数变化作为损伤变量引入到NMAP模型中,建立了考虑含水率损伤的非线性黏弹塑性剪切流变本构模型DNMAP模型。通过对环剪蠕变试验结果曲线的拟合,可以看出DNMAP模型对不同含水率试样蠕变全过程特别是对加速蠕变阶段具有良好的拟合效果。(6)对新建立的非线性黏弹塑性本构模型(DNMAP)进行了详细的公式推导,对其蠕变本构方程进行三维差分形式离散,得到了应力增量的差分表达式。利用FLAC3D内置的FLAC3D500VS2010Addin.msi插件,在Visual studio2010软件中实现了基于分数阶微积分的新建蠕变本构模型的开发。并通过建立一个三维数值计算模型,来模拟计算其单轴压缩蠕变试验结果,证明了新建DNMAP损伤流变本构模型的合理性,也说明其在FLAC3D中的二次开发实现过程的正确性。(7)在介绍峨胜矿区“1270-1380m”平台变形体的基本地质条件和地质环境基础上,考虑软弱夹层的应变软化和流变特性,对变形体进行了渐进性破坏分析和长期稳定性预测研究。在对变形体进行渐进性破坏分析时,分别采用了极限平衡法和基于应变软化模型的容重增加法。结果表明:容重增加法计算所得到的稳定状态的安全系数要略大于极限平衡法运用残余强度所得的安全系数。将容重增加法数值计算过程中不同时步下的剪应变增量分布的变化趋势来表示变形体的渐进性破坏的发展过程。剪应变增量经历从出现、扩展直至稳定的过程。当计算时步达到一定值时,剪应变增量分布趋于稳定,边坡安全系数也不再发生变化。基于边坡位移反分析法利用遗传算法和神经网络对流变模型参数进行了反演,通过实测值和计算值的对比证明了反演参数的合理性以及本文所提出的DNMAP蠕变本构模型的正确性。通过对变形体位移变化和剪应变增量的计算对其稳定性发展趋势进行了预测。
[Abstract]:The rational exploitation and utilization of mineral resources is a very important link in our country's insistence on sustainable development and the deep implementation of the strategic decision of "the development of the west". In the central and western regions of China, Hubei, Hunan, Sichuan, Guizhou, Guangxi, Yunnan, and other provinces, there are slow soft layers (rock layers and interlayer dip angles are less than 25 degrees). The Permian limestone strata, which have rich mineral resources of high quality limestone, are an important source of building materials in the construction of a large number of infrastructure in China. With the continuous exploitation of mining to the deep and high places, more and more strata are exposed in the mine, the exposed strata are becoming more and more complex, and the hydrogeological conditions facing the mine are becoming more complex and added. The disturbance of the slope rock mass leads to the deterioration of the mechanical properties of rock mass. The exposure of various soft strata and the expansion of the side surface of the slope seriously affect the stability and safety of the mine slope. Because of its own particularity, the weak interlayer often becomes the potential sliding surface of the mine slope, and the stability of the mine process slope and the end slope. At the same time, the weak interlayer is also a good seepage channel for water. The water rock action aggravates the deterioration of the mechanical properties of the interlayer and makes the rheological properties of the soft interlayer become more obvious. Therefore, it is very important to study the deterioration law of the mechanical parameters of the soft intercalation to the stability evaluation and safety construction of the mine slope. In this paper, the paper studies the rheological properties and slippery mechanism of the gentle dip and soft intercalation of high slope under the action of rainfall and blasting repeatedly under the National Natural Science Foundation of China (41672317) and the lateral project "demonstration and optimization of the stability of the high and steep slope in the Emei mining field", the Permian system of the Emei mine in Sichuan The soft interlayer of carbonaceous shale in Makou formation is the research object. Considering the hydrogeological environment and meteorological conditions in Sichuan Emei mining area, the conventional ring shear test and cyclic shear creep test under different water content are carried out. Based on the results of conventional ring shear test, the variation of peak strength and residual strength of weak intercalation under different water content is discussed. The deterioration law of the mechanical parameters of the soft interlayer with water content as the damage variable is analyzed. The cyclic shear creep test under different normal pressure of different water content is carried out. On the basis of the analysis of the cyclic shear creep test results, the rheological model parameters, which are caused by the water content of the soft and weak interlayer, are put forward based on the fractional calculus. The nonlinear viscoelastic plastic rheological constitutive model (DNMAP model) is used as the damage variable. The finite difference scheme of the DNMAP rheology model is derived. The two development of the new constitutive model is realized by the FLAC3D two development platform in Microsoft visual studio2010 programming, and its correctness and feasibility are verified. As the research object of the "1270-1380m" excavated platform deformation body of the potential sliding surface, the weak interlayer is studied, the progressive failure analysis and the long-term stability prediction are carried out, and the corresponding prevention and control measures are put forward. The results obtained in this paper are as follows: (1) the Permian Makou in the Sichuan Emei mining field "1270-1380m" excavation platform On the basis of the analysis of the sedimentary environment and the tectonic environment, the formation process of soft intercalation was analyzed on the basis of the analysis of the sedimentary environment and the tectonic environment. The mineral composition, chemical composition and particle size composition of the Permian Maogu group were analyzed by means of mineral identification, X ray and laser particle size distribution instrument. A series of physical and mechanical tests have been carried out to obtain the basic physical parameters of soft intercalation. The study shows that the mineral composition of the soft interlayer of the Maogu group of the Permian is mainly clay minerals and calcite. The hydrophilicity of the clay minerals is stronger, so the water content has a significant influence on the force characteristics of the weak intercalation. (2) the Permian Permian. The shear deformation failure characteristics of the soft interlayer with the same dry density and different moisture content under the action of different normal stress are studied. The study shows that the normal stress is an important factor affecting the strain hardening and softening characteristics of the weak intercalation. The increase of water content and normal stress is the lower method. Specimens with strain softening under stress are characterized by shear dilatancy as the main shear shrinkage during the ring shear test, and the shear dilatancy characteristics of the specimens showing strain hardening under high normal stress show that the shear strain characteristics are influenced by normal pressure and water content. The greater the pressure is, the higher the water content is, the more obvious the strain hardening characteristic of the specimen is. The influence of water content and normal stress on the peak strength and the residual strength of the weak intercalation is analyzed. The test results show the peak shear stress, the residual shear stress and the corresponding shear displacement are all with the moisture content and normal stress of the specimen. Based on the Moore Coulomb strength criterion and the principle of damage mechanics, the damage and deterioration law of water content to the equivalent shear strength parameters of weak intercalation is studied, and a function relation between the damage rate and water content of the shear strength parameters is obtained. The microscopic scanning of the ring shear surface after the ring shear failure of the sample is carried out and the strain softening is discussed. The difference between the strain hardening and the strain hardening specimens on the microstructure, and points out that the difference between the particle displacement, the breakage and the directional arrangement in the ring shear test is an important factor affecting the macroscopic mechanical properties of the specimens. (3) based on the conventional ring shear test results, the water content of the soft interlayer of the Permian Makou formation and the ring shear creep under the different normal pressure are carried out. The shear creep deformation and the strain rate of the sandwich specimens with different water content were analyzed. At the same time, the long-term strength of the weak intercalation under different water content was determined by two methods, and the comparison with the residual strength was made. The experimental results show that (1) when the water cut is lower than the saturated water content, the higher the water cut is, the increase of the instantaneous shear strain increases with the increase of the stress level, and the increment of instantaneous shear strain increases with the increase of water content, and the maximum increment appears near the saturated water content. With the increase of water content, the cumulative creep increment of the specimen is also increasing. From the creep curve to the ratio of the steady creep deformation and the transient elastic strain, the ratio of the steady creep deformation and the transient elastic strain increases with the increase of the cyclic shear stress grade. The higher the stress grade, the creep deformation is in the total deformation. The specific gravity in the creep is more obvious. (2) the influence of water content on the creep deformation rate is mainly reflected on the duration of the creep decay period. The study shows that the creep decay duration is approximately linear with the change of water content. With the increase of the stress grade, the residual stress is 0.6 times. The slope of the fitting line is greater than the fitting line slope of the residual stress. The higher the stress level of the ring shear stress, the slower the growth rate of the creep decay duration. (3) the long-term strength determined by the isochronous stress strain curve method is greater than that determined by the steady creep rate method, but the difference of the value is small. The relationship between the long-term strength and water content of the layer is fitted and analyzed. It is found that the long-term strength and water content have a linear negative correlation. The higher the water content, the lower the long-term strength of the weak intercalation. (4) there is a significant difference in the microscopic characteristics of the specimens with different water content after the creep damage, and the specimen with lower water content is smooth and the deformation scratch is more. It is clear and flaky structure is obvious; with the increase of water content, the sample softens gradually. Because the sample contains expansive clay minerals, the particle becomes denser and isotropic as the expansibility becomes stronger and the isotropy is obvious. Due to the large deformation measurement before the specimen is destroyed, the fracture surface has many gaps and cracks, showing the characteristics of ductility damage. (4) detailed introduction Several common definitions of fractional calculus are used, and some existing rheological element models are improved based on fractional calculus. The creep constitutive equations are given respectively. By fitting the test curves before the creep failure of the soft interlayer under saturated state, a variety of factors are taken into consideration to improve the fractional calculus. The Maxwell element model is the viscoelastic part of the new creep constitutive model. At the same time, it is found that the unsteady parameter Abel pot can describe the characteristics of the creep accelerated failure section. Therefore, a new nonlinear shear creep constitutive model is constructed in parallel with the plastic element and the front improved Maxwell element model. The constitutive model (NMAP) is used to derive the creep constitutive equation. Through the fitting of the accelerated failure section of the specimen ring shear creep, it is found that the newly established NMAP element constitutive model can well fit the whole creep test curve. (5) based on the damage theory, the change of the rheological model parameters caused by the water content of the weak interlayer is used as the damage variable. In the NMAP model, a nonlinear viscoelastic plastic shear rheological constitutive model DNMAP model is established to consider the damage of water content. By fitting the curve of the cyclic shear creep test results, it can be seen that the DNMAP model has a good fitting effect on the whole creep process of different moisture content specimens, especially for the accelerated creep stage. (6) the new model is established. The nonlinear viscoelastic plastic constitutive model (DNMAP) is derived in detail, and its creep constitutive equation is discrete in three dimensional difference form, and the differential expression of stress increment is obtained. A new creeping version based on fractional calculus is realized in Visual studio2010 software by using the built-in FLAC3D500VS2010Addin.msi plug-in of FLAC3D. A three-dimensional numerical model is developed to simulate and calculate the results of the uniaxial compression creep test, which proves the rationality of the new DNMAP damage rheological constitutive model and the correctness of its two development process in FLAC3D. (7) the basic of the "1270-1380m" deformable body in the Emei mining area is introduced. On the basis of geological conditions and geological environment, considering the strain softening and rheological properties of weak intercalation, the progressive failure analysis and long-term stability prediction of the deformable bodies are studied. The limit equilibrium method and the bulk density increase method based on the strain softening model are adopted respectively in the analysis of the progressive failure of the deformable body. The safety factor of the stable state obtained by the heavy increase method is slightly greater than the safety factor of the residual strength of the limit equilibrium method. The progressive failure of the deformation body is represented by the trend of the variation trend of the shear strain increment in the numerical calculation process. The shear strain increment experience is from the emergence. When the calculation step reaches a certain value, the increment distribution of shear strain tends to be stable and the safety factor of slope no longer changes. Based on the inverse analysis method of slope displacement, the parameters of the rheological model are retrieved by the genetic algorithm and neural network, and the inverse parameters are proved by the comparison of the actual and calculated values. Rationality and the correctness of the DNMAP creep constitutive model proposed in this paper. The trend of its stability is predicted by the change of deformation position and the calculation of shear strain increment.
【学位授予单位】：中国地质大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TD31
，

本文编号：2056013