【摘要】：基于自主研發(fā)的"多功能真三軸流固耦合試驗系統(tǒng)",進行了真三軸應力(σ1㧐σ2㧐σ3)條件下,保持體應力不變、改變中主應力系數(shù)的砂巖強度試驗,探討了不同中主應力系數(shù)條件下砂巖的變形、強度及剪切破壞特性。試驗結果表明:在真三軸應力條件下,擴容起點隨中主應力系數(shù)b的增大而呈遞減趨勢。應力加載過程中擴容存在明顯的階段性:隨最大主應力的增加,穩(wěn)定壓縮段,體應變近似呈線性遞增趨勢;加速擴容段,體應變近似呈二次函數(shù)增大,且應變速率呈線性增大。保持體應力不變條件下,砂巖峰值強度隨中主應力系數(shù)b的增大而逐漸降低,符合修正Lade準則。試驗應力條件下,巖樣主要發(fā)生雙斜面對稱剪切破壞,剪切破壞面傾角隨b的增加呈線性增大。
[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】： 重慶大學煤礦災害動力學與控制國家重點實驗室;重慶大學資源及環(huán)境科學學院;重慶大學復雜煤氣層瓦斯抽采國家地方聯(lián)合工程實驗室;
【基金】：國家自然科學基金資助項目(51434003,51374256) 2016重慶市科研創(chuàng)新資助項目(CYS16012)
【分類號】：TD311

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