本文選題：軟巖大變形 + 小凈距隧道��； 參考：《蘭州交通大學(xué)》2014年碩士論文

【摘要】：新建蘭渝鐵路蘭州至廣元段屬多山地區(qū)，該片區(qū)內(nèi)多數(shù)隧道穿越地層為高地應(yīng)力軟弱圍巖、節(jié)理裂隙發(fā)育、圍巖穩(wěn)定性差、板巖層厚較小、薄層特性明顯，多個隧道在施工過程中發(fā)生大變形，嚴(yán)重影響施工安全和施工進(jìn)度；本文以蘭渝鐵路新城子隧道為背景，通過現(xiàn)場監(jiān)控和數(shù)值模擬，以不同支護(hù)結(jié)構(gòu)（長錨桿、雙層初支、雙層二襯）對軟巖小凈距隧道大變形控制效果為主線，分別采用理論分析、現(xiàn)場試驗檢測、數(shù)值模擬等方法對在建新城子隧道小凈距段支護(hù)結(jié)構(gòu)展開研究，以便為后續(xù)更小凈距段提供可靠的理論依據(jù)和技術(shù)支持。 研究內(nèi)容與方法： (1)通過對國內(nèi)外軟巖大變形小凈距隧道支護(hù)結(jié)構(gòu)研究現(xiàn)狀進(jìn)行總結(jié)，本文分析了造成軟巖大變形的原因、敏感因素、機(jī)理、施工控制關(guān)鍵技術(shù)等。 (2)結(jié)合工程實際，對隧道在不同支護(hù)結(jié)構(gòu)（長錨桿、雙層初支、雙層二襯）下圍巖變形及支護(hù)結(jié)構(gòu)受力進(jìn)行監(jiān)測，并分析新城子隧道圍巖及支護(hù)結(jié)構(gòu)變形及受力規(guī)律，對比分析了不同支護(hù)結(jié)構(gòu)支護(hù)效果。 (3)通過MIDAS/GTS軟件對不同支護(hù)結(jié)構(gòu)下隧道施工過程進(jìn)行模擬，繪制圍巖及支護(hù)結(jié)構(gòu)關(guān)鍵部位應(yīng)力應(yīng)變隨施工推進(jìn)的變化曲線，推斷其隨時間和空間變化的規(guī)律，并且對推薦的支護(hù)結(jié)構(gòu)進(jìn)行了不同因素的優(yōu)化對比分析。 (4)通過對比現(xiàn)場實測數(shù)據(jù)與數(shù)值模擬數(shù)據(jù)圍巖中位移和支護(hù)結(jié)構(gòu)受力，綜合評選變形控制效果，，達(dá)到支護(hù)結(jié)構(gòu)優(yōu)化目的。 主要研究成果： (1)造成新城子隧道發(fā)生大變形的主要原因是隧址所處的地質(zhì)狀況是破碎極破碎帶，節(jié)理裂隙嚴(yán)重發(fā)育、地應(yīng)力場較高、圍巖流變作用明顯；圍巖及支護(hù)結(jié)構(gòu)破壞以水平剪切破壞為主，圍巖表現(xiàn)出水平收斂大于豎向沉降，累積變形總量大且周期長的特點。 (2)現(xiàn)場實測分析得到采用三臺階開挖軟巖大變形小凈距隧道變形隨時間變化規(guī)律：拱頂位移變形快速變化時間為20～25天；上臺位移變形快速變化時間為15～20天；下臺位移變形快速變化時間為10～15天。上臺階開挖變形占總變形量的60%~70%，中臺階占總變形量的10%~15%，下臺階占總變形量的5%左右。 (3)通過對不同支護(hù)結(jié)構(gòu)下軟巖小凈距段隧道開挖數(shù)值模擬表明：不同支護(hù)結(jié)構(gòu)下隧道應(yīng)力應(yīng)變變化規(guī)律跟實際接近，隧道位移和應(yīng)力較高的部位都出現(xiàn)在邊墻、拱腳處，比較容易失穩(wěn)，應(yīng)給予加強(qiáng)；后行洞開挖對先行洞位移和支護(hù)結(jié)構(gòu)受力有一定影響，隨著掌子面間距的減小影響會越來越嚴(yán)重。 (4)通過對現(xiàn)場監(jiān)測和數(shù)值模擬分析得出：雙層初支和雙層二襯支護(hù)效果良好，但雙層二襯第一層二襯受力過大，存在安全隱患，故推薦剛度較大的雙層初支，并且雙層初支可通過延遲第二層初支施做和施做前輔以錨桿注漿可達(dá)到進(jìn)一步加固圍巖，充分發(fā)揮其自承能力，減小二襯受力。對于軟巖隧道應(yīng)本著一次支護(hù)充分讓壓，合理釋放圍巖變形能，充分發(fā)揮圍巖自穩(wěn)能力，二次大剛度支護(hù)進(jìn)行補(bǔ)強(qiáng)的原則是科學(xué)合理的，即：“先柔后剛、先放后抗、變形留夠、因勢利導(dǎo)、相互制約、充分改善圍巖穩(wěn)定性”的基本原則。
[Abstract]:The Lanzhou - Guangyuan section of the newly - built Lanzhou - Chongqing Railway belongs to the mountainous area . Most of the tunnel crossing strata in the area are the weak surrounding rock with high ground stress , the joint fissure is developed , the stability of the surrounding rock is poor , the thickness of the plate is small , the characteristics of the thin layer are obvious , and the large deformation of the plurality of tunnels in the construction process seriously affects the construction safety and the construction progress ;
In this paper , based on the Xincheng sub - tunnel of Lanzhou - Chongqing Railway , the control effect of large deformation of soft rock small clear distance tunnel is studied by means of field monitoring and numerical simulation . The main lines are analyzed by theoretical analysis , field test and numerical simulation respectively , so as to provide reliable theoretical basis and technical support for the subsequent smaller net - distance segment .

Study contents and methods :

( 1 ) Through summing up the research status of soft rock large deformation small clear distance tunnel support structure at home and abroad , this paper analyzes the causes , sensitive factors , mechanism and key technology of construction control .

( 2 ) According to the engineering practice , the deformation of the surrounding rock and the stress of the supporting structure of the tunnel under different supporting structures ( long bolt , double - layer initial support and double lining ) are monitored , and the deformation and stress law of surrounding rock and supporting structure of Xincheng sub - tunnel are analyzed , and the supporting effect of different support structures is compared .

( 3 ) To simulate the construction process of tunnel under different support structure through MIDAS / T software , the stress strain of surrounding rock and supporting structure is drawn along with the change curve of construction propulsion , the law of time and space change is inferred , and the optimized contrast analysis of different factors is carried out on the recommended supporting structure .

and ( 4 ) comprehensively evaluating the deformation control effect by comparing the measured data of the field and the numerical simulation data in the surrounding rock of the data simulation data and the stress of the supporting structure , so as to achieve the optimization purpose of the support structure .

Key findings :

( 1 ) The main reason for the large deformation of the new city sub - tunnel is that the geological condition at the tunnel site is the crushing pole crushing zone , the joint fissure is seriously developed , the ground stress field is high , and the rheological effect of the surrounding rock is obvious ;
The failure of surrounding rock and supporting structure is dominated by horizontal shear failure , and the surrounding rock shows that the horizontal convergence is greater than vertical settlement , the total accumulated deformation is large and the period is long .

( 2 ) The field test results show that the deformation of large deformation small clear distance tunnel with three step excavation is changed with time : the rapid change time of displacement deformation of vault is 20 ~ 25 days ;
the rapid change time of the displacement deformation of the upper stage is 15 - 20 days ;
the displacement deformation of the step - down displacement is rapid change time of 10 - 15 days . The upper step excavation deformation accounts for 60 - 70 % of the total deformation amount , the middle step occupies 10 - 15 % of the total deformation amount , and the lower step accounts for about 5 % of the total deformation amount .

( 3 ) The numerical simulation of tunnel excavation of soft rock under different supporting structures shows that the change rule of tunnel stress and strain under different support structures is similar to the actual approach , and the location of tunnel displacement and stress is relatively easy to be unstable and should be strengthened ;
The excavation of the back - row tunnel has some influence on the displacement of the preceding tunnel and the stress of the supporting structure , and the influence of the reduction of the spacing of the palm surface becomes more and more serious .

( 4 ) By analyzing on - site monitoring and numerical simulation , it is concluded that the two - layer primary support and double - layer double lining support have good effect , but the two - layer two - lining first - layer two - layer lining has a large stress and a potential safety hazard , so that the self - bearing capacity of the surrounding rock can be fully exerted , and the stress of the two - layer lining can be reduced .

【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】：U455.7

【參考文獻(xiàn)】

相關(guān)期刊論文 前6條

1 陳秋南,張永興,劉新榮,包太;連拱隧道的設(shè)計理論與動態(tài)施工力學(xué)研究[J];地下空間與工程學(xué)報;2005年01期

2 沈泰;地質(zhì)力學(xué)模型試驗技術(shù)的進(jìn)展[J];長江科學(xué)院院報;2001年05期

3 李樹軍;;高地應(yīng)力大變形隧道變形特性及工程應(yīng)對措施分析[J];水利與建筑工程學(xué)報;2009年03期

4 姚勇;田志宇;;并設(shè)小凈距隧道中巖墻力學(xué)特征及加固措施研究[J];工業(yè)建筑;2006年04期

5 馬時強(qiáng);;幾種控制軟弱圍巖大變形方法的效果評價[J];華東公路;2010年06期

6 張文強(qiáng);王慶林;李建偉;高攀;;木寨嶺隧道大變形控制技術(shù)[J];隧道建設(shè);2010年02期

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