本文選題：循環(huán)荷載　切入點：單裂隙巖體　出處：《西安科技大學》2017年碩士論文　論文類型：學位論文

【摘要】：近年來,我國工程建設速度不斷發(fā)展,更多工程項目涉及寒冷區(qū)域。巖體作為地質(zhì)工程中最主要的部分,均含有自然損傷造成的裂隙,在地下巖體裂隙比較發(fā)育的地區(qū),受季節(jié)和晝夜交替產(chǎn)生的溫度差引起巖體內(nèi)的裂隙反復凍融。因此,展開對凍融～加卸載反復作用下裂隙巖體損傷演化及斷裂特性研究具有重要研究價值。制作具有0°、45°和90°的單裂隙標準試件,通過對單裂隙試件進行10、20、30和40次凍融循環(huán)試驗,得到不同時期各個試件表面均出現(xiàn)不同程度的片狀剝落和龜裂現(xiàn)象;單裂隙角度在相同凍融循環(huán)次數(shù)條件下所造成的局部化損傷效應隨著角度的增大依次減弱;同一角度單裂隙試件隨著凍融循環(huán)次數(shù)的增加局部化損傷效應越明顯;凍融循環(huán)過程對單裂隙端部局部區(qū)域以外產(chǎn)生了近似同等規(guī)律的損傷效應。隨后對試件進行不同應力水平條件循環(huán)加卸載,得到循環(huán)荷載條件下滯回曲線,同時對單裂隙巖體宏觀模式進行分析得到三種典型的破壞模式,分析了等次凍融循環(huán)條件下單裂隙傾角巖體強度。在隨后的理論分析中,對試件在凍融過程中的溫度進行實時測量,得到凍融過程中溫度變化曲線,分析凍脹力演化理論,給出了凍脹力理論表達式。根據(jù)巖石疲勞特性和疲勞理論,對單裂隙巖體端部疲勞累積損傷分析,基于斷裂力學基本理論,對凍脹力和單軸循環(huán)荷載共同作用下的裂紋的擴展機理進行了探討,提出考慮凍融損傷作用導致裂紋長度的增加和材料性質(zhì)劣化影響的Ⅰ和Ⅱ型裂紋應力強度因子的計算表達式。利用顆粒流(PFC2D)軟件對凍融和加卸載條件下不同單裂隙角度和凍融次數(shù)進行模擬分析,結(jié)果與室內(nèi)試驗一致。通過凍融～加卸載共同作用下單裂隙巖體試驗分析和理論推導相結(jié)合,系統(tǒng)分析了單裂隙巖體在該條件下的演化過程,對解決相應寒區(qū)工程問題給出了一定的依據(jù)。
[Abstract]:In recent years, the speed of engineering construction in our country has been developing continuously, and more engineering projects are involved in cold regions. Rock mass, as the most important part of geological engineering, contains cracks caused by natural damage, and in areas where the cracks of underground rock mass are relatively developed, The cracks in the rock are frozen and thawed by the temperature difference between the seasons and the day and night. It is of great value to study the damage evolution and fracture characteristics of fractured rock mass under repeated freeze-thaw loading and unloading. The single fracture standard specimen with 0 擄or 45 擄and 90 擄is made, and the 10 ~ 2030 and 40 freeze-thaw cycle tests are carried out on the single fracture specimen. The results show that there are different degree of flake spalling and crack phenomena on the surface of each specimen in different periods, and the localized damage effect caused by the single crack angle under the same freeze-thaw cycle times is weakened with the increase of the angle. With the increase of freeze-thaw cycles, the local damage effect of the specimen with a single fracture at the same angle is more obvious. The damage effect of freeze-thaw cycle outside the local area of the end of a single fracture is approximately the same. Then the specimen is subjected to cyclic loading and unloading under different stress levels, and the hysteretic curve under cyclic load is obtained. At the same time, three typical failure modes are obtained by analyzing the macroscopic model of single fractured rock mass, and the strength of rock mass with order crack inclination is analyzed under the condition of equivalent freeze-thaw cycle. The temperature change curve during freezing and thawing process is obtained by measuring the temperature of the specimen in real time, the evolution theory of frost heave force is analyzed, and the theoretical expression of frost heave force is given. According to the fatigue characteristics and fatigue theory of rock, Based on the basic theory of fracture mechanics, the crack propagation mechanism under the combined action of frost heaving force and uniaxial cyclic load is discussed. The expressions of stress intensity factors of mode 鈪，

本文編號：1573325