【摘要】：對于巖土類的顆粒材料,在特定的應(yīng)變加載路徑下會發(fā)生非局部化的失穩(wěn)現(xiàn)象,此時應(yīng)力狀態(tài)處于Mohr-Coulomb屈服面內(nèi),試樣整體急劇失穩(wěn)。采用顆粒離散元方法,研究抗轉(zhuǎn)動特性對顆粒材料在等比例應(yīng)變加載路徑下宏、細觀力學(xué)特性的影響。模擬發(fā)現(xiàn),較為松散的試樣更易發(fā)生分散性失穩(wěn),此時顆粒集合體的應(yīng)力-應(yīng)變狀態(tài)滿足Hill材料失穩(wěn)準(zhǔn)則。采用考慮顆粒轉(zhuǎn)動的接觸模型進行離散元模擬,通過改變顆粒間接觸的轉(zhuǎn)動摩擦系數(shù),從宏觀和細觀層面分析等比例應(yīng)變加載路徑中顆粒材料的穩(wěn)定性。顆�？罐D(zhuǎn)動能力的增強可以降低材料發(fā)生分散性失穩(wěn)的可能性,隨著轉(zhuǎn)動摩擦系數(shù)的增加,應(yīng)力路徑由應(yīng)變軟化逐漸轉(zhuǎn)為應(yīng)變硬化,原本會發(fā)生分散性失穩(wěn)的松散顆粒集合體表現(xiàn)出與密實顆粒集合體相似的宏觀力學(xué)特性;顆粒集合體的內(nèi)部結(jié)構(gòu)表現(xiàn)出相應(yīng)的細觀作用機制,轉(zhuǎn)動摩擦系數(shù)的增加有效地抑制了顆粒轉(zhuǎn)動,雖然降低了顆粒體系的配位數(shù),但增加了顆粒之間的接觸力,增強了顆粒體系力鏈結(jié)構(gòu)的穩(wěn)定性和各向異性,形成穩(wěn)定的結(jié)構(gòu)持續(xù)抵抗外荷載的施加,從而試樣整體不會形成松散的接觸狀態(tài)而失去穩(wěn)定性。
[Abstract]:For rock and soil granular materials, the unlocalized instability will occur under a specific strain loading path, where the stress state is within the Mohr-Coulomb yield surface, and the whole specimen is rapidly unstable. The effect of anti-rotation properties on the macro and meso-mechanical properties of granular materials under the isometric strain loading path is studied by means of particle discrete element method. It is found that the loose samples are more prone to the dispersion instability, and the stress-strain state of the granular aggregates meets the Hill instability criterion. The contact model considering particle rotation is used to simulate the stability of particle material in the strain loading path from macroscopic and meso levels by changing the rotational friction coefficient of contact between particles. The enhancement of the anti-rotation ability of particles can reduce the possibility of dispersion instability. With the increase of rotational friction coefficient, the stress path gradually changes from strain softening to strain hardening. Loose particle aggregates, which would otherwise have dispersive instability, exhibit macroscopic mechanical properties similar to those of dense particle aggregates, and the internal structures of particle aggregates exhibit a corresponding meso-mechanism. The increase of rotational friction coefficient effectively inhibits the particle rotation. Although the coordination number of the particle system is reduced, the contact force between particles is increased, and the stability and anisotropy of the force chain structure of the particle system are enhanced. A stable structure is formed to resist the application of external loads, so that the whole specimen will not form a loose contact state and lose its stability.
【作者單位】： 武漢大學(xué)水資源與水電工程科學(xué)國家重點實驗室;武漢大學(xué)水工巖石力學(xué)教育部重點實驗室;
【基金】：國家自然科學(xué)基金青年基金項目(No.51509190);國家自然科學(xué)基金面上項目(51579193) 中國博士后科學(xué)基金面上資助(No.2016T90727)~~
【分類號】：TU43

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