發(fā)布時間：2018-04-02 04:02

  本文選題：裂隙巖體　切入點：裂隙擴展　出處：《重慶大學(xué)》2016年博士論文

【摘要】：本文提出一種新的數(shù)值模擬計算方法-廣義粒子動力學(xué)(GPD)算法對地下裂隙巖體在應(yīng)力、滲流及溫度耦合作用下裂隙擴展機理進行理論及數(shù)值研究。(1)采用Hoek-Brown強度準則對脆性巖體的裂隙啟裂、擴展和連接進行判斷。當(dāng)粒子的應(yīng)力滿足Hoek-Brown強度準則時,粒子失效,根據(jù)失效粒子的破裂順序?qū)α严稊U展路徑進行描述。(2)采用GPD數(shù)值方法,建立巖體系統(tǒng)的應(yīng)力、滲流、損傷耦合模型。模擬研究了含水及不含水情況下,地下隧道開挖卸荷后的裂隙擴展規(guī)律,以及隧道圍巖的位移情況;研究了滲流場對應(yīng)力場及損傷場的影響。(3)本文提出一種新的“生成粒子算法”,來模擬豎向荷載和裂隙水壓耦合作用下巖體裂隙擴展機理。當(dāng)張開裂紋的張開度達到一定程度時,攜帶水粒子參數(shù)的新粒子會在空白區(qū)域生成;根據(jù)Hoek-Brown強度準則對巖石粒子間虛擬鍵的斷裂進行判斷;斷裂虛擬鍵只能夠承受粒子間的壓應(yīng)力作用,而不能承受拉應(yīng)力作用;裂隙水壓對翼型裂紋起裂角及起裂位置有很大影響,隨著裂隙水壓的增大,翼型裂紋的擴展方向與預(yù)置裂紋軸線的夾角逐漸增大,起裂位置逐漸向預(yù)置裂紋軸線方向移動。(4)采用GPD數(shù)值方法,建立巖體的應(yīng)力、溫度、損傷耦合模型。在基質(zhì)熱膨脹系數(shù)小于內(nèi)嵌材料的熱膨脹系數(shù)時,內(nèi)嵌顆粒處于靜水壓力狀態(tài),基質(zhì)材料在徑向方向受壓,環(huán)向方向受拉,由于巖石材料抗拉強度較低,在環(huán)向拉力作用下會產(chǎn)生徑向裂紋;在基質(zhì)熱膨脹系數(shù)大于內(nèi)嵌材料的熱膨脹系數(shù)時,內(nèi)嵌顆粒處于拉伸狀態(tài),基質(zhì)材料則在徑向方向受拉,環(huán)向方向受壓,此時最大拉應(yīng)力位于內(nèi)嵌材料和基質(zhì)材料的接觸面位置,即在接觸面位置,基質(zhì)材料發(fā)生拉伸破壞。(5)在GPD數(shù)值方法中,建立巖體的溫度、滲流耦合計算模型�？紤]溫度場影響時,一方面,洞室開挖后周邊圍巖溫度降低,導(dǎo)致巖體滲透系數(shù)降低;另一方面,溫差的存在對滲流擴散產(chǎn)生影響,導(dǎo)致洞室周邊裂隙水的滲流速度明顯比不考慮溫度場時偏低,滲流跡線在相同滲流時間段內(nèi)擴展長度減小。在滲流作用條件下,由于宏觀裂隙滲流的影響,造成在裂隙處溫度場分布不均,溫度降低較慢,同時由于滲流的影響,隨著計算步加大,溫度場向外擴展,溫度場在含宏觀裂隙的位置出現(xiàn)溫度傳播受阻的情況。這表明,不僅溫度對滲流場有較大影響,滲流場對溫度場也有較大影響。(6)在應(yīng)力、滲流、溫度、損傷耦合情況下,不同側(cè)壓力系數(shù)對洞室周圍巖體損傷區(qū)的擴展有較大影響。當(dāng)側(cè)壓力系數(shù)較小時,洞室拱頂上方及底板下方損傷區(qū)擴展范圍較大,宏觀裂隙開裂水平也較高;隨著側(cè)壓力系數(shù)的增大,洞室周邊拉應(yīng)力區(qū)逐漸減小,宏觀裂隙的開裂水平也逐漸減小;但在開挖卸荷初始階段,圍巖損傷區(qū)卻較側(cè)壓力系數(shù)較小時要大。
[Abstract]:In this paper, a new numerical simulation method, Generalized Particle Dynamics (GPD) algorithm, is proposed for stress analysis of underground fractured rock mass. Theoretical and numerical study on fracture propagation mechanism under coupling of seepage and temperature. (1) Hoek-Brown strength criterion is used to judge fracture initiation, expansion and connection of brittle rock mass. When the stress of particles meets the Hoek-Brown strength criterion, particle failure occurs. According to the fracture sequence of failure particles, the fracture propagation path is described. (2) using GPD numerical method, the coupling model of stress, seepage and damage of rock mass system is established. The law of crack expansion after excavation and unloading of underground tunnel and the displacement of surrounding rock of tunnel; In this paper, a new "particle generation algorithm" is proposed to simulate the crack propagation mechanism of rock mass under the coupling of vertical load and fissure water pressure. The new particles with water particle parameters will be formed in the blank area; according to the Hoek-Brown strength criterion, the fracture of the virtual bond between rock particles can be judged. The fracture virtual bond can only withstand the compressive stress between the particles, but not the tensile stress. The crack water pressure has a great influence on the crack initiation angle and position of the airfoil crack. With the increase of the crack water pressure, the crack propagation direction and the angle between the prefabricated crack axis and the crack propagation direction gradually increase. The stress, temperature and damage coupling model of rock mass is established by GPD numerical method. When the thermal expansion coefficient of matrix is less than the thermal expansion coefficient of embedded material, The embedded particles are under hydrostatic pressure, the matrix material is compressed in the radial direction and the tensile direction is in the circumferential direction. Because of the low tensile strength of the rock material, the radial crack will occur under the action of the toroidal tensile force. When the thermal expansion coefficient of the matrix is larger than the coefficient of thermal expansion of the embedded material, the embedded particles are in the tensile state, while the matrix material is pulled in the radial direction and compressed in the circumferential direction. In this case, the maximum tensile stress is located at the interface position of the embedded material and the matrix material, that is, the tensile failure of the matrix material occurs at the contact plane position. In the GPD numerical method, the temperature of the rock mass is established. Considering the influence of temperature field, on the one hand, the temperature of surrounding rock decreases after excavation, which leads to the decrease of permeability coefficient of rock mass; on the other hand, the existence of temperature difference has an effect on seepage diffusion. As a result, the seepage velocity of fissure water around the cavern is obviously lower than that when temperature field is not taken into account, and the length of seepage trace is decreased in the same seepage period. Under the condition of seepage, because of the influence of macroscopic fissure seepage, As a result of the uneven distribution of temperature field in the fracture, the decrease of temperature is slow. At the same time, due to the influence of seepage, with the increase of calculation step, the temperature field expands outwards, and the temperature field appears to be blocked in the position of macroscopic fissure. Not only does temperature have a great effect on the seepage field, but also the seepage field has a great effect on the temperature field.) in the case of stress, seepage, temperature and damage coupling, Different lateral pressure coefficients have great influence on the expansion of rock mass damage zone around the cavern. When the lateral pressure coefficient is small, the damage area above the arch roof and the bottom plate of the cavern is larger, and the macroscopic crack cracking level is also higher. With the increase of lateral pressure coefficient, the tensile stress zone around the cavern decreases gradually, and the crack level of macroscopic crack decreases gradually, but in the initial stage of excavation and unloading, the damage zone of surrounding rock is larger than the lateral pressure coefficient.
【學(xué)位授予單位】：重慶大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2016
【分類號】：TU45

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