本文選題：圍巖穩(wěn)定性 + 圍巖分級(jí)　； 參考：《西南交通大學(xué)》2017年碩士論文

【摘要】：地下工程開挖過程中,圍巖強(qiáng)度低于二次應(yīng)力,圍巖進(jìn)入塑形變形階段并形成塑性區(qū),如果不及時(shí)支護(hù),其頂部圍巖極易塌落,塌落部分在頂部圍巖一定深度范圍以內(nèi),形成塌落拱。為此,研究地下空間工程開挖引起圍巖穩(wěn)定性變化、圍巖塌落拱規(guī)律,不僅有理論意義,而且有重要的實(shí)用價(jià)值。目前,我國(guó)雙線鐵路隧道圍巖復(fù)合式襯砌的初期支護(hù)由錨桿、噴射混凝土、鋼筋網(wǎng)及鋼架等組合而成。為了研究實(shí)際工程中各個(gè)初期支護(hù)部分對(duì)隧道穩(wěn)定性的影響,本論文以蒙華鐵路九嶺山隧道為依托,結(jié)合FLAC~(3d)有限差分強(qiáng)度折減法,通過開展現(xiàn)場(chǎng)實(shí)驗(yàn),對(duì)隧道圍巖穩(wěn)定性及塌落拱的塌落效應(yīng)進(jìn)行研究,主要內(nèi)容包括:(1)利用FLAC~(3d)有限差分強(qiáng)度折減法,對(duì)隧道圍巖的破壞模式進(jìn)行預(yù)判。對(duì)九嶺山隧道雙線鐵路隧道Ⅱ～Ⅴ級(jí)圍巖的安全系數(shù)進(jìn)行了分析,得到無支護(hù)情況下Ⅱ～Ⅴ級(jí)圍巖有無系統(tǒng)錨桿段隧道安全系數(shù)分別為3.05(Ⅱ級(jí)圍巖)、3.40(Ⅲ級(jí)圍巖系統(tǒng)錨桿段)、3.35(Ⅲ級(jí)圍巖無系統(tǒng)錨桿段)、3.14(Ⅳ級(jí)圍巖系統(tǒng)錨桿段)、3.45(Ⅳ級(jí)圍巖無系統(tǒng)錨桿段)、2.85(V級(jí)圍巖系統(tǒng)錨桿段)、2.90(V級(jí)圍巖無系統(tǒng)錨桿段),說明本文所依托背景工程研究區(qū)域內(nèi),隧道開挖后圍巖強(qiáng)度能夠抵抗所受應(yīng)力,即隧道破壞不是應(yīng)力控制型破壞,此外還分析了隧道在破壞過程中的破壞形式,折減后破壞部位出現(xiàn)在邊墻、拱頂。(2)Ⅱ～Ⅴ級(jí)圍巖錨桿受力普遍較小,但整體未出現(xiàn)明顯塌落拱式受力狀態(tài),分析認(rèn)為錨桿受力主要來自于隧道周邊的破碎圍巖(幾何不穩(wěn)定體)的松動(dòng)荷載,并不存在塌落拱荷載,試驗(yàn)段錨桿僅是對(duì)隧道周邊的破碎圍巖(幾何不穩(wěn)定體)起到一定的錨固作用。試驗(yàn)中系統(tǒng)錨桿支護(hù)試驗(yàn)段初期支護(hù)受力明顯大于無系統(tǒng)錨桿支護(hù)試驗(yàn)段,說明錨桿起到了一定的作用。(3)噴射混凝土和格柵鋼架受力相比于材料極限抗壓強(qiáng)度較小,具有較大安全儲(chǔ)備。但結(jié)合錨桿受力分析認(rèn)為并不存在塌落拱荷載,各個(gè)試驗(yàn)段埋深相對(duì)應(yīng)的圍巖在一定埋深范圍內(nèi)自承載能力較好,理想狀態(tài)下能夠自穩(wěn),初期支護(hù)受力主要來自于隧道周邊的破碎圍巖(幾何不穩(wěn)定體)的松動(dòng)荷載(形變壓力)。(4)不同圍巖級(jí)別試驗(yàn)段圍巖巖體的破碎情況和節(jié)理裂隙發(fā)育情況,能從一定程度上反映圍巖形變壓力大小,初期支護(hù)受力與支護(hù)的時(shí)機(jī)和圍巖的應(yīng)力釋放有關(guān),圍巖地下水情況也對(duì)初期支護(hù)的受力也有很大的影響。(5)Ⅳ級(jí)圍巖拱頂下沉累計(jì)值7.62mm和水平收斂累計(jì)值11.70mm,V級(jí)圍巖拱頂下沉累計(jì)值2.6mm和水平收斂累計(jì)值4.56mm,隧道整體向凈空側(cè)變形,與試驗(yàn)中格柵鋼架和噴射混凝土普遍受壓的數(shù)據(jù)相符合,說明試驗(yàn)段圍巖隧道初期支護(hù)主要為小偏心受壓構(gòu)件。
[Abstract]:In the excavation process of underground engineering, the strength of surrounding rock is lower than the secondary stress, and the surrounding rock enters into the plastic deformation stage and forms plastic zone. If not supported in time, the top wall rock is easy to collapse, and the collapse part is within a certain depth range of the top surrounding rock.Form a collapse arch.Therefore, it is not only of theoretical significance but also of important practical value to study the stability of surrounding rock caused by excavation of underground space engineering and the law of collapse arch of surrounding rock.At present, the initial support for the composite lining of the surrounding rock of the double-track railway tunnel in China is composed of bolt, shotcrete, steel mesh and steel frame.In order to study the influence of various initial supporting parts on tunnel stability in practical engineering, this paper, based on Jiuling Mountain Tunnel of Monghua Railway, combined with FLACU / 3 D) finite difference strength reduction method, carried out field experiments.The stability of tunnel surrounding rock and the collapse effect of collapse arch are studied. The main contents include: 1) the failure mode of tunnel surrounding rock is forecasted by using the finite difference strength reduction method.The safety factor of class 鈪，

本文編號(hào)：1766478