(1. 中南大學 資源與安全工程學院，長沙 410083；
2. 中國瑞林工程技術(shù)有限公司，南昌 330031)
摘 要: 對不同內(nèi)徑的大理巖圓環(huán)試樣進行靜態(tài)和動態(tài)劈裂試驗，研究其在不同加載速率下的抗拉強度和破壞模式隨內(nèi)外徑比值(ρ)的變化規(guī)律。結(jié)果表明:圓盤試樣的動態(tài)抗拉強度約為其靜態(tài)抗拉強度的5倍。圓環(huán)試樣的破壞模式與試樣內(nèi)徑大小以及加載速率有關(guān)。在靜載試驗條件下，當試樣內(nèi)外徑比較小(ρ<0.3)時，試樣以沿加載徑向劈裂破壞為主，而隨著內(nèi)外徑比的增大，在垂直加載方向上產(chǎn)生次生拉伸裂紋。在沖擊荷載作用下，圓環(huán)破裂成4塊，且當試樣內(nèi)外徑比為0.5時，次生裂紋靠近入射桿。采用Hobbs公式計算的抗拉強度均比巴西圓盤的劈裂強度大，且靜態(tài)劈裂試驗的峰值荷載和圓環(huán)試樣的內(nèi)外徑比呈負指數(shù)變化規(guī)律。利用圓環(huán)試樣確定的巖石抗拉強度更像是材料的一種試驗指標而不是材料屬性。
關(guān)鍵字: 巖石；圓環(huán)；巴西劈裂試驗；抗拉強度；分離式霍普金森壓桿；破壞模式
（1. School of Resources and Safety Engineering, Central South University, Changsha 410083, China;
2. China Nerin Engineering Co., Ltd., Nanchang 330031, China）
Abstract:Static and dynamic splitting tests were conducted on ring marble specimens with different internal diameters to study the tensile strength and failure modes with the change of the ratio of internal radius to external radius (ρ) under different loading rates. The results show that the dynamic tensile strength of disc rock specimen is approximately five times its static tensile strength. The failure modes of ring specimens are related to the dimension of the internal hole and loading rate. Under static loading tests, when the ratio of internal radius to external radius of the rock ring is small enough (ρ<0.3), specimens mostly split along the diametral loading line. With the increase of the ratio, the secondary cracks are formed in the direction perpendicular to the loading line. Under dynamic loading tests, specimens usually break up into four pieces. When the ratio ρ reaches 0.5, the secondary cracks are formed near the input bar. The tensile strength calculated by Hobbs’ formula is greater than the Brazilian splitting strength. The peak load and the radius ratio show a negative exponential relationship under static test. Using ring specimen to determine tensile strength of rock material is more like a test indicator rather than the material properties.
Key words: rock; circular ring; Brazilian splitting test; tensile strength; split Hopkinson pressure bar; failure pattern
