發(fā)布時間：2018-04-03 14:18

  本文選題：軟巖大變形　切入點(diǎn)：小凈距隧道　出處：《蘭州交通大學(xué)》2014年碩士論文

【摘要】：國內(nèi)外對于軟巖大變形小凈距隧道的圍巖變形研究還不多見，，再加上有些已建成的軟巖大變形小凈距隧道出現(xiàn)襯砌裂紋、地表裂縫、洞門墻開裂及中墻柱開裂等情況，故對此類隧道的力學(xué)行為進(jìn)行理論研究與施工方案探討。 本文以蘭渝鐵路新城子隧道為背景，應(yīng)用大型通用有限元分析軟件（MIDAS/GTS），對隧道的施工過程進(jìn)行有限元數(shù)值仿真模擬，研究在不同臺階開挖長度和不同左右線隧道掌子面距離條件下，進(jìn)行隧道變形和支護(hù)單元受力模擬分析，綜合現(xiàn)場監(jiān)控量測數(shù)據(jù)，取得了以下成果： （1）造成新城子隧道發(fā)生大變形的主要原因是隧道所處的地應(yīng)力場是高地應(yīng)力場，巖體被切割擠壓成小塊狀，另外節(jié)理裂隙異常發(fā)育，促使巖體的自穩(wěn)能力低下，圍巖表現(xiàn)出位移增大期較長，累積變形總量大的特點(diǎn)。 （2）根據(jù)現(xiàn)場監(jiān)測數(shù)據(jù)整理分析，采用三臺階開挖法軟巖大變形小凈距隧道的變形時間規(guī)律：拱頂沉降變化288mm，上臺階水平收斂值最大，達(dá)到354mm；上臺階位移變形急速變化時間為25天；中臺階位移變形急速變化時間為20天；下臺階位移變形急速變化時間為15天。圍巖壓力增長期為70天；接觸壓力增長期為50天，從拱部到側(cè)墻，隨著空間自上而下變化，其應(yīng)力最終值逐漸減��；且通過分析得出，長錨桿對于控制圍巖凈空收斂方面有很好的效果。 （3）通過模擬三種工況開挖隧道，對比拱頂沉降、水平收斂及支護(hù)應(yīng)力，畫出了他們的位移和應(yīng)力隨施工步的變化曲線圖，分析得出：采用工況Ⅰ開挖隧道時，拱頂沉降、水平收斂、各初支單元的受力、鋼拱架軸向應(yīng)力、噴射混凝土應(yīng)力、二襯混凝土應(yīng)力及錨桿軸力受力均比采用工況Ⅱ、工況Ⅲ時小。綜合考慮變形控制、洞室穩(wěn)定等方面，認(rèn)為在新城子隧道所處條件下，采用3m臺階長度較為合理，有利于圍巖的自穩(wěn)，有效發(fā)揮圍巖的自承能力，且拱頂下沉和水平收斂值較小，初支和二襯單元受力比較均勻，更多的削弱了初支單元和二襯單元受力集中范圍，保證洞室本身的穩(wěn)定性。 （4）通過不同左右線掌子面距離的模擬分析結(jié)果可以看出，拱頂沉降、水平收斂值隨著掌子面距離的增大而減小，且變化速率隨著距離增大而減小。工況一、工況二和工況三施工時隧道位移變化較大，且該三種工況施工時隧道位移的變化有較大區(qū)別，而工況四和工況五差別不是很大，工況五的變形略大于工況四的變形。通過綜合分析左右線隧道掌子面距離的變化對拱頂沉降值和水平收斂值的影響，在本文分析的情況中，左右線隧道掌子面距離為30m或40m時的相對效果較好，拱頂沉降和水平收斂值較前三種工況小，此距離可有效控制拱頂沉降和水平收斂變形，有利于洞室的穩(wěn)定。
[Abstract]:Both at home and abroad for the large deformation of soft rock tunnel with small spacing deformation studies are still rare, small spacing tunnel lining crack, surface crack of large deformation of soft rock and some have been built, and the column wall portal wall cracking cracking and so on, so that the mechanical behavior of the tunnel in theory and construction study of scheme.
Based on the background of Metro Tunnel on Lanzhou Chongqing railway, the application of finite element analysis software (MIDAS/GTS), finite element numerical simulation for tunnel construction process and research in different excavation step length and different distance line around the tunnel face under the condition of tunnel deformation and support element stress analysis, comprehensive the site monitoring data, the following results have been achieved:
(1) the main reason caused by metro tunnel is large deformation tunnel where the stress field is high stress field, rock cut squeeze into small blocks, and joint abnormalities, prompted the rock stability of surrounding rock is low, showing displacement increases over a long period of time, the total cumulative deformation characteristics.
(2) according to the on-site monitoring data analysis, using three step excavation of large deformation of the small spacing tunnel method in soft rock vault settlement changes 288mm, the step level convergence value of the largest, up to 354mm; the step displacement rapid change time is 25 days; the step displacement rapid change time for 20 days step displacement; rapid change time is 15 days. The surrounding rock pressure of growth for a period of 70 days; the contact pressure increase for a period of 50 days, from the arch to the side wall, with the changes in the stress space from top to bottom, the final value decreases gradually; and the long bolt, have very good effect to control tunnel convergence.
(3) by simulating three kinds of conditions of tunnel excavation, comparison of crown settlement and horizontal convergence supporting stress, draw their displacement and stress with the construction step of change curve shows the condition of tunnel excavation, crown settlement, horizontal convergence, the initial supporting force of single element steel arch, axial stress, shotcrete stress, two lining concrete stress and axial force of the anchor force are compared with the condition II, III. Considering the condition of small deformation control on tunnel stability, that the conditions in the metro tunnel, the 3M step length is more reasonable, is conducive to the surrounding rock stability, effectively play the self-supporting capacity of the rock and the crown settlement and horizontal convergence value is smaller, the initial support and lining two unit force uniform, more weakened the primary support unit and the two unit lining stress concentration range, to ensure the stability of cavern itself.
(4) through different simulation results about distance line tunnel face can be seen, vault settlement, horizontal convergence value decreases with increasing the distance of the tunnel face, and the rate of change with distance increases. The first condition, operating mode two and three during the construction of tunnel displacement changes greatly, and the changes of three kinds of tunnel construction conditions when the displacement is quite different, and the operating mode four and five difference is not large, the deformation condition five is slightly larger than the effect of deformation of four conditions. Through the comprehensive analysis about the changes of the distance line of the tunnel face to the vault sedimentation and horizontal convergence value in this paper, analysis of the situation, about the distance line of tunnel face for the better effect of 30m or 40m relative to the crown settlement and horizontal convergence than before in the three conditions, the distance can effectively control the settlement of vault and horizontal convergence deformation, is conducive to the stability of the cavern.

【學(xué)位授予單位】：蘭州交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：U455.4

【相似文獻(xiàn)】

相關(guān)期刊論文 前10條

1 侯春艷;城市地鐵小凈距隧道過站區(qū)的微震控制爆破施工技術(shù)[J];鐵道標(biāo)準(zhǔn)設(shè)計(jì);2005年04期

2 王玉成;小凈距隧道開挖及中夾巖墻加固施工技術(shù)[J];山西建筑;2005年10期

3 楊轉(zhuǎn)運(yùn),王羽,劉會;雙洞小凈距隧道施工控制要點(diǎn)[J];現(xiàn)代隧道技術(shù);2005年02期

4 姜鵬;李建強(qiáng);;淺談石獅小凈距隧道的施工[J];華東公路;2005年04期

5 溫東平;;淺談小凈距隧道支護(hù)結(jié)構(gòu)設(shè)計(jì)原則與施工措施[J];科技資訊;2006年01期

6 高維權(quán);;地鐵小凈距隧道過站區(qū)的微震控制爆破施工技術(shù)[J];西部探礦工程;2006年07期

7 喬春江;朱光儀;;超小凈距隧道的設(shè)計(jì)與研究[J];公路;2006年07期

8 秦衛(wèi);王飛;;小凈距隧道設(shè)計(jì)研究與應(yīng)用[J];土工基礎(chǔ);2006年04期

9 蔣團(tuán)結(jié);蘇煥予;;小凈距隧道在山區(qū)高速公路中的應(yīng)用[J];西部交通科技;2006年05期

10 王耀明;王飛;;小凈距隧道設(shè)計(jì)與結(jié)構(gòu)分析[J];交通標(biāo)準(zhǔn)化;2006年11期

相關(guān)會議論文 前10條

1 劉亮;黃明;鐘祖良;梁寧慧;;高速公路小凈距隧道建設(shè)關(guān)鍵技術(shù)分析[A];第十屆全國青年巖石力學(xué)與工程學(xué)術(shù)大會論文集[C];2009年

2 賴錦興;;里洋小凈距隧道設(shè)計(jì)[A];2001年全國公路隧道學(xué)術(shù)會議論文集[C];2001年

3 黃波;;小凈距隧道施工技術(shù)要點(diǎn)[A];第二屆全國公路科技創(chuàng)新高層論壇論文集（上卷）[C];2004年

4 姚勇;何川;田志宇;;小凈距隧道爆破振動特征及控爆分析[A];城市地下空間開發(fā)與地下工程施工技術(shù)高層論壇論文集[C];2004年

5 汪子勇;孟凡良;;小凈距隧道施工[A];全國礦山建設(shè)學(xué)術(shù)會議論文選集（下冊）[C];2004年

6 T3家惠;曾何

本文編號：1705562