【摘要】：基于自主研發(fā)的"多功能真三軸流固耦合試驗(yàn)系統(tǒng)",進(jìn)行了真三軸應(yīng)力(σ1㧐σ2㧐σ3)條件下,保持體應(yīng)力不變、改變中主應(yīng)力系數(shù)的砂巖強(qiáng)度試驗(yàn),探討了不同中主應(yīng)力系數(shù)條件下砂巖的變形、強(qiáng)度及剪切破壞特性。試驗(yàn)結(jié)果表明:在真三軸應(yīng)力條件下,擴(kuò)容起點(diǎn)隨中主應(yīng)力系數(shù)b的增大而呈遞減趨勢(shì)。應(yīng)力加載過(guò)程中擴(kuò)容存在明顯的階段性:隨最大主應(yīng)力的增加,穩(wěn)定壓縮段,體應(yīng)變近似呈線(xiàn)性遞增趨勢(shì);加速擴(kuò)容段,體應(yīng)變近似呈二次函數(shù)增大,且應(yīng)變速率呈線(xiàn)性增大。保持體應(yīng)力不變條件下,砂巖峰值強(qiáng)度隨中主應(yīng)力系數(shù)b的增大而逐漸降低,符合修正Lade準(zhǔn)則。試驗(yàn)應(yīng)力條件下,巖樣主要發(fā)生雙斜面對(duì)稱(chēng)剪切破壞,剪切破壞面傾角隨b的增加呈線(xiàn)性增大。
[Abstract]:Based on the "multifunctional true triaxial fluid-solid coupling test system", a sandstone strength test was carried out under the condition of true triaxial stress (蟽 1? 蟽 2? 蟽 3), which kept the body stress unchanged and changed the principal stress coefficient. The deformation, strength and shear failure characteristics of sandstone under different medium principal stress coefficients are discussed. The experimental results show that under the condition of true triaxial stress, the starting point of expansion decreases with the increase of the principal stress coefficient b. During the stress loading, there are obvious phases: with the increase of the maximum principal stress, the volume strain increases linearly in the steady compression section, and in the accelerated expansion section, the volume strain approximate increases as a quadratic function and the strain rate increases linearly. The peak strength of sandstone decreases with the increase of the mid-principal stress coefficient b under the condition of keeping the body stress constant, which is in line with the modified Lade criterion. Under the experimental stress condition, the double inclined plane symmetrical shear failure occurs mainly, and the slope of the shear failure plane increases linearly with the increase of b.
【作者單位】： 重慶大學(xué)煤礦災(zāi)害動(dòng)力學(xué)與控制國(guó)家重點(diǎn)實(shí)驗(yàn)室;重慶大學(xué)資源及環(huán)境科學(xué)學(xué)院;重慶大學(xué)復(fù)雜煤氣層瓦斯抽采國(guó)家地方聯(lián)合工程實(shí)驗(yàn)室;
【基金】：國(guó)家自然科學(xué)基金資助項(xiàng)目(51434003,51374256) 2016重慶市科研創(chuàng)新資助項(xiàng)目(CYS16012)
【分類(lèi)號(hào)】：TD311

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