本文選題：FLAC　切入點(diǎn)：PFC　出處：《重慶交通大學(xué)》2015年碩士論文

【摘要】：隧道作為地下結(jié)構(gòu)物,受到的荷載主要來自周圍土體的壓力和約束。目前規(guī)范中對(duì)隧道所受荷載是以深淺埋為界來劃分的。深淺埋的界限是以壓力拱理論為依據(jù),認(rèn)為壓力拱以上的土體荷載對(duì)隧道不再起作用,隧道的荷載主要來自壓力拱以下的土體的壓力。在地震中,隧道襯砌受到的四周土體產(chǎn)生的作用力還是主要荷載。但在地震時(shí)隧道上方的壓力拱是否依然存在?如果存在,壓力拱的高度是否發(fā)生了變化?震后壓力拱的高度與震前是否發(fā)生了變化?這些問題還無從所知。這些問題是計(jì)算地震作用下隧道上方荷載必須解決的問題。為了更好的研究隧道上方土體與隧道襯砌相互作用的問題,必須先研究清楚上述問題。近些年離散元被廣泛應(yīng)用于巖土大變形和破壞的細(xì)觀機(jī)理研究。離散元能從細(xì)觀方面觀察巖土的受力及破壞情況。因此被廣泛用于研究巖土的微觀力學(xué)行為,以及研究微觀參數(shù)和宏觀參數(shù)的關(guān)系。但采用離散元模擬實(shí)際巖土工程問題時(shí)需要大量的顆粒,對(duì)于目前的計(jì)算機(jī)處理水平無疑是一個(gè)巨大的挑戰(zhàn)。此時(shí)離散-連續(xù)耦合分析方法應(yīng)運(yùn)而生,對(duì)巖土的大變形區(qū)、破裂區(qū)或者需要特別關(guān)注的區(qū)域采用離散元模擬,而其他區(qū)域采用連續(xù)單元進(jìn)行模擬。這樣即利用了離散元的優(yōu)點(diǎn),又解決了計(jì)算時(shí)間較長的問題。本文在理論分析的基礎(chǔ)上編制了耦合程序,利用耦合程序模擬了隧道在靜力和地震作用下的受力情況,分析了壓力拱的高度問題。本文主要得到的成果有:①編寫了“擬FLAC”程序,可完成靜力與動(dòng)力計(jì)算,幫助充分理解FLAC2D的實(shí)現(xiàn)過程。②編寫了離散-連續(xù)耦合程序,為研究巖土工程數(shù)值模擬新方法做出貢獻(xiàn)。③封裝了模型生成、室內(nèi)壓縮實(shí)驗(yàn)和巴西劈裂實(shí)驗(yàn)的函數(shù),可以更快的生成理想模型和測量模型的宏觀力學(xué)參數(shù)。④從力的傳遞路徑改變方面給出了壓力拱形成的原因,真正從微觀方面解釋了壓力拱的形成過程,對(duì)于充分理解壓力拱及壓力拱的范圍確定給出參考。⑤研究地震作用時(shí)壓力拱是否存在問題為以后隧道工程設(shè)計(jì)提供參考。
[Abstract]:As underground structures, tunnels are mainly subjected to the pressure and constraints of surrounding soil.In the current code, the load on the tunnel is divided by depth and shallow burying.The boundary of deep and shallow burying is based on the theory of pressure arch. It is considered that the soil load above the pressure arch no longer acts on the tunnel, and the load of tunnel mainly comes from the pressure of soil below the pressure arch.In the earthquake, the soil force around the tunnel lining is still the main load.But does the pressure arch over the tunnel still exist during the earthquake?If so, has the height of the pressure arch changed?Has the height of the post-earthquake pressure arch changed?These questions are unknown.These problems must be solved to calculate the load above the tunnel under earthquake action.In order to better study the interaction between soil and tunnel lining above the tunnel, the above problems must be studied clearly.In recent years, discrete elements have been widely used to study the mesoscopic mechanism of large deformation and failure of rock and soil.The discrete element can observe the stress and failure of rock and soil from the view of meso.Therefore, it is widely used to study the micromechanical behavior of rock and soil and the relationship between microscopic and macroscopic parameters.But using discrete element to simulate the actual geotechnical engineering problems requires a large number of particles, which is undoubtedly a great challenge to the current computer processing level.At this time, the discrete-time coupled analysis method emerges as the times require. The discrete element is used to simulate the large deformation zone, the fracture zone or the area needing special attention, while the continuous element is used to simulate the other regions.In this way, the advantage of discrete element is utilized, and the problem of long calculation time is solved.On the basis of theoretical analysis, a coupling program is developed in this paper. By using the coupling program, the stress of the tunnel under static and seismic action is simulated, and the height of the pressure arch is analyzed.The main results of this paper are as follows: 1 wrote the "quasi FLAC" program, which can accomplish static and dynamic calculation, and help to fully understand the realization process of FLAC2D. 2. A discrete-time and continuous coupling program is written.In order to study the new method of geotechnical engineering numerical simulation, the paper encapsulates the functions of model generation, indoor compression experiment and Brazilian splitting experiment.The macroscopic mechanical parameters of the ideal model and the measurement model. 4. The causes of the formation of the pressure arch are given in terms of the change of the force transfer path, and the formation process of the pressure arch is really explained from the micro aspect.In order to fully understand the range of pressure arch and pressure arch, the paper gives the reference .5 to study whether the pressure arch exists in earthquake action or not, which provides a reference for future tunnel engineering design.
【學(xué)位授予單位】：重慶交通大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：U451

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

1 何川;耿萍;晏啟祥;;Ⅳ級(jí)圍巖鐵路隧道抗震計(jì)算上覆土柱合理計(jì)算高度[J];土木工程學(xué)報(bào);2013年05期

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本文編號(hào)：1710595