基于PFC^(3D)的裂隙岩石间接拉伸强度研究

Investigation of Indirect Tensile Strength of Fractured Rock Based on PFC^(3D)

利用PFC3D中颗粒间接触粘结模型研究细观参数值对拉伸强度、微裂隙数量和破坏方式的影响。分别建立不同厚度的完整试样、单裂隙试样和随机多裂隙试样。以相同的加载方式,研究了不同厚度试样的间接拉伸强度,并得出如下结论:(1)接触粘结强度控制着宏观试样的强度,影响接触粘结的破坏方式,接触粘结易在粘结强度较低的方向破坏;(2)完整试样间接拉伸强度受厚度变化影响较小,但裂隙对试样拉伸强度有较强的削弱作用,不同厚度单裂隙试样的拉伸强度变化不明显;(3)试样内部较多裂隙对岩石拉伸强度有较大影响,随机裂隙越多,试样拉伸强度就表现出较强的尺寸效应,但拉伸强度还受试样尺寸的影响。

With a contact-bond model at each particle-particle contact point,the effects of micro-parameters on tensile strength,number and failure mode of micro-cracks were studied. Intact,one fissured and random multiple fissured numerical samples with different thickness were established and indirect tensile strength of different samples were obtained,some conclusions come as follows,（ 1） tensile strength of numerical samples is controlled by contact-bond strength,failure mode of contact-bond depends on contact-bond strength while failure of contact-bond easily happens at some contact-bond with lower shear strength or normal strength;（ 2） the different thickness have little influence on indirect tensile strength of intact sample,but fissure in the sample can greatly reduce tensile strength,also there is no great variation of tensile strength of one fissured samples with different thickness;（ 3） multiple fissures have a great effect on rock tensile strength,the bigger number of fissures,the greater size effect of tensile strength has,and tensile strength is mainly influenced by sample size.