岩石RHT模型理论及主要参数确定方法研究

发布时间：2018-01-12 00:31

  本文关键词：岩石RHT模型理论及主要参数确定方法研究　出处：《中国矿业大学(北京)》2016年博士论文　论文类型：学位论文

  更多相关文章： RHT模型 参数确定方法 LA-DYNA 数值模拟 正交试验 SHPB

【摘要】：岩石与混凝土同为脆性材料,具有相似的颗粒边界、孔洞以及裂隙等不同尺度缺陷,且二者都具有应变硬化、损伤软化和应变率效应等特性,这就为我们利用混凝土的本构关系来描述岩石类脆性材料在动、静载作用下的力学行为提供了可行性,其中,RHT混凝土本构模型己被广泛地应用于爆炸冲击、侵彻等问题的数值模拟和分析中并取得令人相对满意的效果。RHT模型共计包含34个参数,其中部分参数可以通过试验和理论计算准确获得,部分参数为模型给定值,但也有部分参数的试验获取途径复杂且不易准确测定,而多数学者在利用RHT模型模拟岩石爆破破碎时,不管岩石种类如何变化,对待这些不易获取的参数只是引用混凝土的相关参数或者在其基础上进行简单的调整。由于不同岩石材料在力学性能上的差异,势必会导致其值的确定具有或大或小的偏差,而这些取值的偏差很可能会对数值模拟的结果造成重要影响。因此,本文通过理论分析、静力学试验、波速测定试验、SHPB冲击试验以及数值模拟相结合的方法对RHT模型参数的确定进行研究。(1)系统研究了RHT模型中p-a状态方程、失效面方程、弹性极限面方程、线性强化段方程和损伤软化段方程间的相互作用关系以及不同方程参数代表的含义,并对34个模型参数进行了分类；(2)运用LS-DYNA软件对混凝土RHT模型参数进行了相同应变率下的单轴压缩、单轴拉伸、三轴压缩以及不同应变率下的单轴压缩和单轴拉伸等单元模拟测试,通过将模拟曲线与混凝土经典试验曲线对比研究发现：RHT模型能够较好的描述材料在压应力情况下的力学行为,而在描述拉应力作用下材料力学性能方面存在缺陷；(3)研究了19个RHT模型参数的获取方式,采用LS-DYNA模拟石灰岩单轴(低应变率和高应变率情况下)、三轴压缩的方式对剩余的15个参数进行敏感性分析,在单一改变B、gt*、N、pcomp、ft*、fs*、A、n、Q0、gc*、ξ、D1、εpm、 Af或者nf的情况下,通过研究模拟曲线所发生的变化发现：罗德角相关系数B和拉伸屈服面参数gt*的取值变化对单轴、三轴压缩应力-应变曲线没有影响；拉压强度比ft*、剪压强度比fs*、初始损伤参数D1对损伤软化方程中失效应力面与残余应力面间的曲线形状有着不同程度影响；在单轴压缩情况下,拉压子午比参数Q0、最小失效应变εpm对损伤软化方程中失效应力面与残余应力面间的曲线形状有着一定程度影响,但在三轴压缩情况下,Q0和εpm取值的变化对应力-应变曲线无影响；在单轴压缩情况下,压缩屈服面参数gc*对曲线弹性段、线性强化段以及损伤软化方程中失效应力面与残余应力面间的曲线形状有着重要影响,但在三轴压缩情况下,gc*取值的变化对应力-应变曲线无影响；孔隙度指数N、孔隙压实时压力pcomp、失效面参数A、失效面指数n和剪切模量缩减系数ξ对曲线的线性强化段以及损伤软化方程中失效应力面与残余应力面间的曲线形状度有着不同程度的影响；残余应力强度参数Af和残余应力强度指数nf对损伤软化段的曲线形状有着重要影响；为了验证B和gt*在多种材料作用下的敏感性,对混凝土、闪长岩、石灰岩的模型参数计算模型,单一改变B或者gt*的取值,利用LS-DYNA对三种材料进行单轴压缩、单轴拉伸和三轴压缩进行了数值模拟,计算结果显示：B和gt*可取定值,鉴于B和gt*试验获取难度较大,本文建议选用混凝土相关参数取值,即B=0.0105、gt*=0.7；(4)详细研究分析了21个RHT模型参数的确定方式,对于A、n、fs*、ft*、 Q0、gc*、ξ、D1、εpm、Af、nf、pcomp和N等RHT模型中较难获取的参数,提出了以静力学试验、声波测试试验以及SHPB中击试验为基础,LS-DYNA数值模拟SHPB冲击试验为手段,通过正交试验对参数A、n、fs*、ft*、Q0、gc*、ξ、D1、 εpm、Af、nf、pcomp和N进行确定的方法；(5)利用本文提出的RHT模型参数确定方法,以静力学试验、声波测试试验以及SHPB冲击试验为基础,LS-DYNA数值模拟为手段,通过将正交试验模拟结果与SHPB冲击试验曲线进行对比研究,完成了花岗岩、大理岩和红砂岩模型参数A、n、fs*、ft*、Q0、gc*、ξ、D1、εpm、Af、nf、pcomp和N的测定,得到了花岗岩、大理岩和红砂岩的RHT模型参数；并采用本文所确定花岗岩RHT模型参数,利用LS-DYNA对弹丸侵彻花岗岩靶进行数值模拟,模拟结果与文献试验结果的较好吻合说明了所采用材料模型参数的正确性,证明了本文提出的RHT模型参数确定方法的有效性。
[Abstract]:Rock and concrete with brittle material, which is similar to the grain boundary, holes and cracks and other defects of different scales, and the two is strain hardening, softening and strain rate effect and other characteristics, as we use concrete constitutive relation to describe brittle materials such as rock moving, static mechanical behavior under the action of the provision of the feasibility of the RHT constitutive model of concrete has been widely used in the explosion, numerical simulation and analysis of penetration problem and effect.RHT model has a relatively satisfactory total contains 34 parameters, which can accurately obtain some parameters by experiments and theoretical calculation, some parameters for a given model the value of the test, but there are also some parameters of access to complex and not easy accurate determination, and many of them in the simulation of rock fragmentation by RHT model, no matter how changes of rock types. The relevant parameters to be not easy to get these parameters only by concrete or simple adjustment on its basis. Due to the difference in the mechanical properties of rock material, will inevitably lead to the value determined with the deviation of large or small, and the deviation of the value can have an important influence on numerical simulation results. Therefore, through theoretical analysis, static test, wave velocity test, impact test and SHPB method combining numerical simulation to determine the parameters of RHT model were studied. (1) studied the P-A equation of state RHT model, failure surface equation, elastic limit equation, linear equation and damage section strengthening the interaction between softening section equation and meanings of different parameters represented, and classify the 34 model parameters; (2) using LS-DYNA software for RHT model parameters of concrete The same strain rate under uniaxial compression, uniaxial tension, three axial compression and uniaxial compression under different strain rate and tensile element simulation test, through the simulation curve and the comparative study of concrete classical test curve shows that RHT model can describe the mechanical behavior of materials in compressive force. In the description of tensile defect of mechanical properties of materials under the action of force; (3) obtained on 19 parameters of RHT model, using LS-DYNA simulation of limestone uniaxial (low strain rate and high strain rate conditions), three axial compression method for sensitivity analysis of the parameters in the remaining 15. Single gt*, N, B, pcomp, ft*, fs*, A, N, Q0, gc*, e, D1, e PM, Af or NF, through the simulation of change curve showed that the variation of Rhodes angle correlation coefficient B and tensile yield surface parameters of single axis gt* three. There should be no effect of uniaxial compression stress-strain curve; ratio of tensile strength to compressive strength ft*, shear compression ratio of fs*, initial damage on damage softening failure stress equation of surface and residual stress curves between stress have different degree of influence parameter D1; under uniaxial compression, tensile and compressive radial ratio parameters Q0 the minimum failure strain pm on damage softening equation of failure stress and residual stress curve of force between a certain effect, but in the case of three axial compression, no influence of Q0 and E value of PM stress-strain curve; under uniaxial compression, the compression yield surface parameters the gc* curve of elastic linear hardening, and damage softening equation of failure stress surface and residual stress curve between stress has an important influence, but in the case of three axial compression, no influence of gc* values of stress - strain curve; porosity index N, pore compaction When the pressure is pcomp, the failure surface parameters A, failure surface index n and shear modulus reduction coefficient of linear curve equation in the strengthening stage and damage softening failure stress and residual stress between the surface shape of the curve degree have different effects; residual stress intensity parameter Af and residual stress intensity index NF have an important influence on the curve shape damage softening section; in order to verify the sensitivity of B and gt* in a variety of materials under the action of concrete, diorite, calculation model of model parameters of limestone, value of B or gt* single change of the three materials under uniaxial compression using LS-DYNA, uniaxial tension and three axis compression is simulated, the results show that the B and gt* desirable value, whereas B and gt* test is difficult to obtain, this paper suggested the use of concrete related parameters, namely B=0.0105, gt*=0.7; (4) the detailed research and analysis of 21 RHT 妯″瀷鍙傛暟鐨勭‘瀹氭柟寮，

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