高應力巖體動力擾動下發(fā)生巖爆的試驗研究進展報告

李夕兵 宮鳳強 杜坤 李地元

摘要：深部巖石工程在開挖卸荷過程中，儲存在高應力巖體內的應變能力會被釋放，從而導致圍巖破裂并有可能誘發(fā)巖爆等動力災害。為了研究三維受力的高應力巖體在卸荷條件的力學特性和破壞模式，從高地應力受力環(huán)境出發(fā)，利用自行研制的巖石真三軸電液伺服誘變 （擾動）試驗系統(tǒng)，深入研究真三軸卸荷狀態(tài)下高應力巖石的力學特性及動載荷誘發(fā)巖爆的可能性，揭示深部巖爆災害的擾動誘發(fā)機理。獲得研究成果：利用真三軸電液伺服誘變 （擾動）試驗系統(tǒng)對不同應力狀態(tài)下花崗巖、紅砂巖及水泥砂漿的立方試件進行了真三軸卸載壓縮破壞試驗。研究結果表明卸載后二維受力下巖石的抗壓強度隨中間主應力的增大而增大，但增大的幅度逐漸降低。當單軸壓縮或中間主應力較小時，巖石破壞模式為剪切破壞；隨著中間主應力的增大，花崗巖和紅砂巖的破壞模式逐漸由剪切破壞轉變?yōu)榘辶哑茐模嗌皾{在高應力卸載下仍然發(fā)生塑性大變形剪切破壞。

關鍵詞：深部巖體；高應力；巖爆；動力擾動

Abstract：For deep rock engineerings， the high strain energy stored in deep rock mass may be induced to release in the process of excavation unloading and rockburst and slabbing failure of rock can be resulted. In order to understand the influence of rock types and stress paths on the occurrence of mechanical properties and failure mode， experimental studies were carried out on granite， red sandstone and cement mortar cubic specimens under true triaxial unloading condition. The tests were completed by using a self-developed triaxial electro-hydraulic servo controlled testing system. At first， three dimensional stresses were applied on a cubic rock specimen until the magnitude of stress reaching to a predefined geostress level. Afterwards， the force along the minimum principal stress direction was unloaded， and then the force along the maximum principal stress direction was loaded until the rock specimen got final failure. Testing results showed that the peak strength was increased with the increase of the intermediate principal stress. Meanwhile， the failure modes of granite and red sandstone specimen were changed from shear to slabbing with certain intermediate principal stress. In contrast， the failure mode of cement mortar specimen under triaxial unloading condition was still shear and large plastic deformation was observed.

Keywords：Deep rock mass； high stress； rock burst； dynamic disturbance

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