(1. 中南大學(xué) 資源與安全工程學(xué)院，長(zhǎng)沙 410083；
2. 武漢理工大學(xué) 資源與環(huán)境工程學(xué)院，武漢 430070)
摘 要: 凍融作用下巖石的動(dòng)態(tài)力學(xué)特性研究對(duì)揭示巖石凍融損傷機(jī)理及寒區(qū)巖體工程凍融災(zāi)害防控具有很重要的意義，通過(guò)選取5組砂巖試樣，按照-30~20 ℃的溫度范圍開(kāi)展0、20、40、60和80次的凍融循環(huán)，并利用霍普金森壓桿裝置對(duì)凍融循環(huán)后的試樣開(kāi)展沖擊氣壓為0.45 MPa的動(dòng)態(tài)力學(xué)試驗(yàn)，從動(dòng)態(tài)應(yīng)力-應(yīng)變曲線、動(dòng)態(tài)強(qiáng)度、峰值應(yīng)變和破壞形式等方面對(duì)凍融循環(huán)下砂巖的動(dòng)力性特性和破壞規(guī)律進(jìn)行研究。結(jié)果表明：砂巖的動(dòng)力學(xué)性能隨凍融次數(shù)的增加而降低，其主要的力學(xué)指標(biāo)如動(dòng)態(tài)彈性模量、動(dòng)態(tài)強(qiáng)度及峰值應(yīng)變均有所劣化；砂巖內(nèi)部損傷隨凍融次數(shù)的增加而累積，但累積速度不均勻，當(dāng)凍融次數(shù)為40時(shí)，速度變緩，這一現(xiàn)象在砂巖飽水質(zhì)量、孔隙度、強(qiáng)度和峰值應(yīng)變曲線上都有體現(xiàn)；砂巖的破壞程度隨凍融循環(huán)次數(shù)的增加而增加，當(dāng)循環(huán)次數(shù)為0~40時(shí)，其破壞形式與未凍融時(shí)類似，以軸向的拉伸破壞為主；當(dāng)循環(huán)次數(shù)為60和80時(shí)，試樣碎塊呈均勻細(xì)小化分布。
關(guān)鍵字: 凍融循環(huán)；砂巖；巖石力學(xué)特性；沖擊試驗(yàn)；動(dòng)力破壞
（1. School of Resources and Safety Engineering, Central South University, Changsha 410083, China;
2. School of Resources and Environment Engineering, Wuhan University of Technology, Wuhan 430070, China）
Abstract:Dynamic properties study on rock under freeze-thaw cycles is meaningful for revealing the rock damage mechanism under freeze-thaw and preventing the freezing-thawing disaster of geotechnical engineering in cold regions. The freeze-thaw cycles experiments of 0, 20, 40, 60 and 80 times during -30 ℃ to 20 ℃ by five groups sandstone samples were made, and then, the SPHB was used to test the dynamic mechanical properties of sandstone samples under the constant impact load which is 0.45 MPa, the sandstones dynamic mechanical properties and failure characteristics were studied from the dynamic stress strain curves, dynamic strength, peak strain and failure modes. The results show that, as the freeze-thaw cycle increasing, the sandstones dynamic mechanical property decreases, the main mechanical indices, such as dynamic elasticity modulus, dynamic strength and peak strain, are degradation. The inner damage grows with the increasing of the freeze-thaw cycles times, but the growth rate is uneven, the growth rate slow down at 40 times freeze-thaw cycles and this phenomenon also reflects in indices, such as saturated mass, porosity, strength and peak strain. The damage degree of sandstone samples also increases with the increase of the freeze-thaw cycles times, and which is similar to none freeze-thaw, the dynamic damage mode is main tensile fracture by axial direction at 0-40 times cycles, and the fragments of samples are even and tiny at 60 and 80 times cycles.
Key words: freeze-thaw cycle; sandstone; rock mechanical property; impact mechanical experiment; dynamic damage
