凝灰质粉砂岩力学特性试验及蠕变本构模型研究

发布时间：2018-04-08 14:19

本文选题：凝灰质粉砂岩　切入点：单轴压缩　出处：《西华大学》2017年硕士论文

【摘要】：蠕变特性作为岩土最重要的力学特性之一,直接关系到土木工程建筑的稳定性和安全性。蠕变是质点在外力作用下沿晶体边界扩散或质点穿过晶体内部空穴扩散而表现出的一种宏观现象。随着基础建设工程中地下工程的不断涌现,蠕变对工程建筑的影响效应越来越大,如隧道围岩断裂、边坡失稳和巷道底鼓等不良现象。另一方面,地下建筑往往深埋于地底,受水环境作用,蠕变效应表现得更为明显。虽然目前有许多岩石蠕变方面的研究成果,但是对于岩体在不同含水率下的蠕变研究并不多见,因此本文结合前人的相关研究成果,制备凝灰质粉砂岩试件,并对其进行了在不同含水状态下的常规力学特性试验和单轴蠕变试验,并结合试验结果进行理论分析。主要的研究工作及成果如下:(1)对从“路湾隧道”现场采集新鲜的凝灰质粉砂岩按照《工程岩体试验方法标准》GB/T50266-2013中的规定,将凝灰质粉砂岩岩样加工成长宽为100*50mm的圆柱体,并采用“沸腾法”将试件制备为四种不同含水率状态,分别为?(28)%0、?(28)%41.0、?(28)%75.0、?(28)%04.1。(2)采用MTS-815型岩石材料力学试验机,对加工好的岩样进行单轴压缩试验,获得了四种含水率状态下的弹性模量、泊松比、单轴抗压强度值和应力——应变曲线,为单轴蠕变试验的分级荷载提供了试验数据基础。(3)对凝灰质粉砂岩进行了耐崩解性试验和X射线衍射试验,结果表明凝灰质粉砂岩是由石英(50%)、斜长石(19%)、伊利石(9%)、方解石(15%)、绿泥石(5%)和黄铁矿(2%)所组成的一种具有中等耐久性的泥岩。(4)基于凝灰质粉砂岩饱和状态下的单轴压缩试验结果,推导了单轴蠕变试验的分级荷载等级值,采用岩石三轴蠕变试验机,基于“陈氏加载法”获得了四种不同含水状态下的岩样的单轴蠕变试验曲线,分析了在相同含水率不同荷载等级下和相同荷载等级不同含水率情况下的凝灰质粉砂岩的蠕变变化规律。(5)基于岩样的蠕变曲线性质,采用burgers模型来模拟衰减蠕变阶段和等速蠕变阶段的蠕变曲线。同时引进一种非线性的黏塑性元件,将该黏塑性元件与传统的burgers模型串联得到一种改进的burgers模型,将其命名为SBN-burgers模型,用改进后的模型模拟岩样蠕变曲线的加速蠕变阶段,并推导了该模型的一维和三维应力状态下的蠕变本构方程。(6)基于Originpro数据处理软件,利用软件强大的自定义函数拟合曲线功能,基于Levenberg—Marquardt算法,对SNB-burgers模型一维蠕变本构模型参数进行了回归反演,将得到的理论蠕变曲线与试验蠕变曲线相比较,其相关系数均在0.9以上,表明“SBN-burgers”模型能较好地模拟凝灰质粉砂岩的单轴蠕变特性。
[Abstract]:As one of the most important mechanical properties of rock and soil, creep property is directly related to the stability and safety of civil engineering buildings.Creep is a macroscopic phenomenon in which the particle diffuses along the crystal boundary or the particle diffuses through the hole in the crystal under the action of external force.With the continuous emergence of underground engineering in infrastructure construction, the influence of creep on engineering buildings is becoming more and more serious, such as tunnel surrounding rock fracture, slope instability and roadway floor bulging and other bad phenomena.On the other hand, the creep effect of underground buildings is more obvious due to the effect of water environment.Although there are a lot of research achievements on rock creep at present, there are few researches on creep of rock mass under different moisture content.The conventional mechanical property tests and uniaxial creep tests were carried out under different aqueous conditions, and the theoretical analysis was carried out on the basis of the experimental results.Poisson's ratio, uniaxial compressive strength and stress-strain curves, which provide experimental data basis for graded load of uniaxial creep test, are used to test the disintegration resistance and X-ray diffraction of tuffaceous siltstone.The graded load grade values of uniaxial creep tests are derived. Based on Chen's loading method, the uniaxial creep test curves of four kinds of rock samples with different water content are obtained by using a rock triaxial creep testing machine.The creep variation law of tuffaceous siltstone under the same water content and different load levels and different moisture content is analyzed. The creep curve properties of rock samples are analyzed.The burgers model is used to simulate the creep curves of the attenuated creep stage and the isokinetic creep stage.At the same time, a nonlinear viscoplastic element is introduced. An improved burgers model is obtained by connecting the viscoplastic element with the traditional burgers model. The modified model is named SBN-burgers model. The improved model is used to simulate the accelerated creep stage of the creep curve of rock samples.The creep constitutive equation under one and three dimensional stress states of the model is derived. The creep constitutive equation is based on Originpro data processing software. The function of fitting curves by using the software's self-defined function is used, and based on the Levenberg-Marquardt algorithm, the creep constitutive equation of the model is derived.The parameters of one-dimensional creep constitutive model of SNB-burgers model are regressed. The theoretical creep curve is compared with the experimental creep curve, and the correlation coefficient is above 0.9.It is shown that the "SBN-burgers" model can well simulate the uniaxial creep characteristics of tuffaceous siltstone.
【学位授予单位】：西华大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU452

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