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

【摘要】：近年來(lái),我國(guó)工程建設(shè)速度不斷發(fā)展,更多工程項(xiàng)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(fù)凍融。因此,展開(kāi)對(duì)凍融～加卸載反復(fù)作用下裂隙巖體損傷演化及斷裂特性研究具有重要研究?jī)r(jià)值。制作具有0°、45°和90°的單裂隙標(biāo)準(zhǔn)試件,通過(guò)對(duì)單裂隙試件進(jìn)行10、20、30和40次凍融循環(huán)試驗(yàn),得到不同時(shí)期各個(gè)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(yīng)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(yīng)越明顯;凍融循環(huán)過(guò)程對(duì)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(yīng)。隨后對(duì)試件進(jìn)行不同應(yīng)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(shí)對(duì)單裂隙巖體宏觀模式進(jìn)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(qiáng)度。在隨后的理論分析中,對(duì)試件在凍融過(guò)程中的溫度進(jìn)行實(shí)時(shí)測(cè)量,得到凍融過(guò)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(dá)式。根據(jù)巖石疲勞特性和疲勞理論,對(duì)單裂隙巖體端部疲勞累積損傷分析,基于斷裂力學(xué)基本理論,對(duì)凍脹力和單軸循環(huán)荷載共同作用下的裂紋的擴(kuò)展機(jī)理進(jìn)行了探討,提出考慮凍融損傷作用導(dǎo)致裂紋長(zhǎng)度的增加和材料性質(zhì)劣化影響的Ⅰ和Ⅱ型裂紋應(yīng)力強(qiáng)度因子的計(jì)算表達(dá)式。利用顆粒流(PFC2D)軟件對(duì)凍融和加卸載條件下不同單裂隙角度和凍融次數(shù)進(jìn)行模擬分析,結(jié)果與室內(nèi)試驗(yàn)一致。通過(guò)凍融～加卸載共同作用下單裂隙巖體試驗(yàn)分析和理論推導(dǎo)相結(jié)合,系統(tǒng)分析了單裂隙巖體在該條件下的演化過(guò)程,對(duì)解決相應(yīng)寒區(qū)工程問(wèn)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(hào)：1573325