本文關(guān)鍵詞：巖石RHT模型理論及主要參數(shù)確定方法研究　出處：《中國礦業(yè)大學(xué)(北京)》2016年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： RHT模型 參數(shù)確定方法 LA-DYNA 數(shù)值模擬 正交試驗(yàn) SHPB

【摘要】：巖石與混凝土同為脆性材料,具有相似的顆粒邊界、孔洞以及裂隙等不同尺度缺陷,且二者都具有應(yīng)變硬化、損傷軟化和應(yīng)變率效應(yīng)等特性,這就為我們利用混凝土的本構(gòu)關(guān)系來描述巖石類脆性材料在動、靜載作用下的力學(xué)行為提供了可行性,其中,RHT混凝土本構(gòu)模型己被廣泛地應(yīng)用于爆炸沖擊、侵徹等問題的數(shù)值模擬和分析中并取得令人相對滿意的效果。RHT模型共計(jì)包含34個(gè)參數(shù),其中部分參數(shù)可以通過試驗(yàn)和理論計(jì)算準(zhǔn)確獲得,部分參數(shù)為模型給定值,但也有部分參數(shù)的試驗(yàn)獲取途徑復(fù)雜且不易準(zhǔn)確測定,而多數(shù)學(xué)者在利用RHT模型模擬巖石爆破破碎時(shí),不管巖石種類如何變化,對待這些不易獲取的參數(shù)只是引用混凝土的相關(guān)參數(shù)或者在其基礎(chǔ)上進(jìn)行簡單的調(diào)整。由于不同巖石材料在力學(xué)性能上的差異,勢必會導(dǎo)致其值的確定具有或大或小的偏差,而這些取值的偏差很可能會對數(shù)值模擬的結(jié)果造成重要影響。因此,本文通過理論分析、靜力學(xué)試驗(yàn)、波速測定試驗(yàn)、SHPB沖擊試驗(yàn)以及數(shù)值模擬相結(jié)合的方法對RHT模型參數(shù)的確定進(jìn)行研究。(1)系統(tǒng)研究了RHT模型中p-a狀態(tài)方程、失效面方程、彈性極限面方程、線性強(qiáng)化段方程和損傷軟化段方程間的相互作用關(guān)系以及不同方程參數(shù)代表的含義,并對34個(gè)模型參數(shù)進(jìn)行了分類；(2)運(yùn)用LS-DYNA軟件對混凝土RHT模型參數(shù)進(jìn)行了相同應(yīng)變率下的單軸壓縮、單軸拉伸、三軸壓縮以及不同應(yīng)變率下的單軸壓縮和單軸拉伸等單元模擬測試,通過將模擬曲線與混凝土經(jīng)典試驗(yàn)曲線對比研究發(fā)現(xiàn)：RHT模型能夠較好的描述材料在壓應(yīng)力情況下的力學(xué)行為,而在描述拉應(yīng)力作用下材料力學(xué)性能方面存在缺陷；(3)研究了19個(gè)RHT模型參數(shù)的獲取方式,采用LS-DYNA模擬石灰?guī)r單軸(低應(yīng)變率和高應(yīng)變率情況下)、三軸壓縮的方式對剩余的15個(gè)參數(shù)進(jìn)行敏感性分析,在單一改變B、gt*、N、pcomp、ft*、fs*、A、n、Q0、gc*、ξ、D1、εpm、 Af或者nf的情況下,通過研究模擬曲線所發(fā)生的變化發(fā)現(xiàn)：羅德角相關(guān)系數(shù)B和拉伸屈服面參數(shù)gt*的取值變化對單軸、三軸壓縮應(yīng)力-應(yīng)變曲線沒有影響；拉壓強(qiáng)度比ft*、剪壓強(qiáng)度比fs*、初始損傷參數(shù)D1對損傷軟化方程中失效應(yīng)力面與殘余應(yīng)力面間的曲線形狀有著不同程度影響；在單軸壓縮情況下,拉壓子午比參數(shù)Q0、最小失效應(yīng)變εpm對損傷軟化方程中失效應(yīng)力面與殘余應(yīng)力面間的曲線形狀有著一定程度影響,但在三軸壓縮情況下,Q0和εpm取值的變化對應(yīng)力-應(yīng)變曲線無影響；在單軸壓縮情況下,壓縮屈服面參數(shù)gc*對曲線彈性段、線性強(qiáng)化段以及損傷軟化方程中失效應(yīng)力面與殘余應(yīng)力面間的曲線形狀有著重要影響,但在三軸壓縮情況下,gc*取值的變化對應(yīng)力-應(yīng)變曲線無影響；孔隙度指數(shù)N、孔隙壓實(shí)時(shí)壓力pcomp、失效面參數(shù)A、失效面指數(shù)n和剪切模量縮減系數(shù)ξ對曲線的線性強(qiáng)化段以及損傷軟化方程中失效應(yīng)力面與殘余應(yīng)力面間的曲線形狀度有著不同程度的影響；殘余應(yīng)力強(qiáng)度參數(shù)Af和殘余應(yīng)力強(qiáng)度指數(shù)nf對損傷軟化段的曲線形狀有著重要影響；為了驗(yàn)證B和gt*在多種材料作用下的敏感性,對混凝土、閃長巖、石灰?guī)r的模型參數(shù)計(jì)算模型,單一改變B或者gt*的取值,利用LS-DYNA對三種材料進(jìn)行單軸壓縮、單軸拉伸和三軸壓縮進(jìn)行了數(shù)值模擬,計(jì)算結(jié)果顯示：B和gt*可取定值,鑒于B和gt*試驗(yàn)獲取難度較大,本文建議選用混凝土相關(guān)參數(shù)取值,即B=0.0105、gt*=0.7；(4)詳細(xì)研究分析了21個(gè)RHT模型參數(shù)的確定方式,對于A、n、fs*、ft*、 Q0、gc*、ξ、D1、εpm、Af、nf、pcomp和N等RHT模型中較難獲取的參數(shù),提出了以靜力學(xué)試驗(yàn)、聲波測試試驗(yàn)以及SHPB中擊試驗(yàn)為基礎(chǔ),LS-DYNA數(shù)值模擬SHPB沖擊試驗(yàn)為手段,通過正交試驗(yàn)對參數(shù)A、n、fs*、ft*、Q0、gc*、ξ、D1、 εpm、Af、nf、pcomp和N進(jìn)行確定的方法；(5)利用本文提出的RHT模型參數(shù)確定方法,以靜力學(xué)試驗(yàn)、聲波測試試驗(yàn)以及SHPB沖擊試驗(yàn)為基礎(chǔ),LS-DYNA數(shù)值模擬為手段,通過將正交試驗(yàn)?zāi)M結(jié)果與SHPB沖擊試驗(yàn)曲線進(jìn)行對比研究,完成了花崗巖、大理巖和紅砂巖模型參數(shù)A、n、fs*、ft*、Q0、gc*、ξ、D1、εpm、Af、nf、pcomp和N的測定,得到了花崗巖、大理巖和紅砂巖的RHT模型參數(shù)；并采用本文所確定花崗巖RHT模型參數(shù),利用LS-DYNA對彈丸侵徹花崗巖靶進(jìn)行數(shù)值模擬,模擬結(jié)果與文獻(xiàn)試驗(yàn)結(jié)果的較好吻合說明了所采用材料模型參數(shù)的正確性,證明了本文提出的RHT模型參數(shù)確定方法的有效性。
[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，

本文編號：1411935