發(fā)布時間：2018-01-04 03:28

  本文關(guān)鍵詞：透水砂層泥水平衡盾構(gòu)開挖面失穩(wěn)破壞機理研究　出處：《北京交通大學(xué)》2014年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 透水砂層 大直徑 泥水平衡盾構(gòu) 開挖面 穩(wěn)定性

【摘要】：近年來,中國地下工程進入建設(shè)高峰期,盾構(gòu)法施工因其具有效率高,擾動小,在國內(nèi)尤其是軟土、砂土地區(qū)快速的被推廣應(yīng)用開來。然而,伴隨著盾構(gòu)法的快速發(fā)展,諸多技術(shù)問題也應(yīng)運而生。其中,盾構(gòu)開挖施工對周邊環(huán)境影響問題就是目前困擾國內(nèi)隧道工程領(lǐng)域?qū)＜液蛯W(xué)者們的一項難題,尤其是大直徑盾構(gòu)施工,其開挖面穩(wěn)定是影響周邊環(huán)境的主要因素。如何確保大直徑盾構(gòu)施工開挖面穩(wěn)定,避免施工擾動對周圍環(huán)境的影響是解決城市隧道工程建設(shè)問題的關(guān)鍵,該問題的有效解決勢必將推動未來城市隧道工程的發(fā)展。然而,關(guān)于上述問題,目前國內(nèi)的研究技術(shù)水平和發(fā)展速度遠遜于日本和歐美各國,尤其是透水砂層大型泥水平衡盾構(gòu)開挖面失穩(wěn)機理和評判計算方法的研究尚存諸多不足。本文依托于南京長江隧道工程,對高透水性砂質(zhì)地層中泥水平衡盾構(gòu)隧道開挖面穩(wěn)定性問題展開研究,通過靜三軸試驗、室內(nèi)模型試驗、數(shù)值模擬及理論計算,系統(tǒng)研究了不同泥漿配比、覆土厚度、水頭高度和土體性質(zhì)等工況下開挖面失穩(wěn)特性,對高透水性砂土地層開挖面失穩(wěn)的判據(jù)進行重新界定,建立了適合于砂土地層的開挖面支護力計算公式。主要研究內(nèi)容包括： (1)泥漿配比對開挖面土體強度的影響研究。泥水平衡盾構(gòu)施工中,泥漿在開挖面形成的泥膜作為維持開挖面穩(wěn)定的支護力傳遞介質(zhì),直接作用于開挖面土體,是影響開挖面穩(wěn)定的關(guān)鍵因素之一。通過室內(nèi)三軸試驗,對比分析了不同圍壓下注漿前后土體性質(zhì)和強度等變化特性。研究發(fā)現(xiàn)泥漿成膜過程中,會使砂土的粘聚力上升而內(nèi)摩擦角降低,且隨著圍壓升高,土體強度會有所增加； (2)開挖面主動破壞影響因素研究。通過室內(nèi)模型試驗,對不同泥漿配比、覆土厚度、水頭高度和土體性質(zhì)等工況下開挖面主動破壞的情況進行了對比研究。研究表明,覆土厚度和水頭高度對開挖面的穩(wěn)定性影響較大,隨著覆土厚度增加,開挖面支護力逐漸增大；開挖過程中土中滲流和超孔隙水壓力變化會降低開挖面穩(wěn)定性；從初始開挖到失穩(wěn)整個變化過程中,存在土拱效應(yīng)現(xiàn)象,在干砂試驗中這種現(xiàn)象越發(fā)顯著。影響開挖面穩(wěn)定的因素,除土拱效應(yīng)作用外,更為關(guān)鍵的是內(nèi)摩擦角、覆土厚度和水頭高度； (3)泥水劈裂效應(yīng)研究。在泥水盾構(gòu)掘進施工過程中,泥水壓力設(shè)定過高會引發(fā)泥水劈裂。從而導(dǎo)致泥水艙內(nèi)壓力急劇下降,開挖面失穩(wěn)。通過室內(nèi)模型試驗,同樣對不同泥漿配比、覆土厚度、水頭高度和土體性質(zhì)等工況下泥水劈裂現(xiàn)象進行了研究。研究表明,泥水劈裂壓力與泥漿配比、水頭高度和土體性質(zhì)密切相關(guān),②號泥漿的劈裂壓力要明顯高于①號泥漿；無水時發(fā)生劈裂需要提供的劈裂壓力和時間要高于有水的情況,意味著在地層飽和時更容易發(fā)生劈裂；土體的級配、粘聚力和內(nèi)摩擦角等性質(zhì)直接影響泥水劈裂的效果,粉細砂的泥水劈裂壓力要高于中粗砂； (4)開挖面穩(wěn)定評判方法研究。傳統(tǒng)意義上開挖面破壞主要指主被動滑動破壞。而室內(nèi)模型試驗研究表明,在砂土中,高泥水壓力下泥水劈裂比被動滑動破壞更容易發(fā)生,因此建議開挖面被動破壞的支護力上限值應(yīng)以泥漿劈裂壓力為準(zhǔn)。此外,通過理論計算,提出了適用于砂質(zhì)土層開挖面失穩(wěn)判斷的修正穩(wěn)定系數(shù)法； (5)支護力計算方法研究。通過理論計算,分析研究了目前常用的支護力計算公式,并通過實例驗證了日本經(jīng)驗公式的適用性。此外,對透水砂層中泥水隧道掘進中開挖面支護力取值問題進行了參數(shù)分析,建立了透水砂層泥水盾構(gòu)施工開挖面支護力經(jīng)驗計算公式,并給出了砂土地層中淺覆土隧道支護力比安全取值范圍為1.38-2.14。
[Abstract]:In recent years, Chinese entered the underground engineering construction peak, shield construction due to the advantages of high efficiency, little disturbance, especially in the domestic soft soil, sandy soil area by rapid popularization and application of them. However, with the rapid development of shield technology, many problems have emerged. Among them, the shield excavation on the surrounding environment influence of construction problems is a problem plaguing the experts in the field of tunnel engineering and domestic scholars, especially the large diameter shield construction, the excavation face stability is the main factor affecting the surrounding environment. How to ensure that the large diameter shield excavation face stability, avoid the influence of construction disturbance to the surrounding environment is the key to solve the problems in the construction of city tunnel project, will to effectively solve the problem to promote future development potential of the city tunnel project. However, on these issues, the current research and the technical level of domestic development speed far less In Japan and Europe and the United States, especially the permeable sand large slurry balance shield excavation face stability calculation method and evaluation mechanism of loss exist many shortcomings. Based on the Nanjing Yangtze River tunnel project, the high permeable Sandy Stratum in slurry shield tunnel excavation face stability problem is studied through static triaxial test, three, indoor model test, numerical simulation and theoretical calculation, study different slurry ratio, soil thickness, water level and soil properties under the conditions of excavation face stability characteristics of high permeable sand soil layer excavation surface to define the failure criterion, suitable for sand soil layer excavation face support force calculation formula. The main research contents include the establishment:
(1) study on slurry ratio influence on soil strength. The excavation face of shield construction slurry, mud in the mud film excavation surface formed as maintain the stability of tunnel face supporting pressure transfer medium, directly on the soil of excavation face, is one of the key factors affecting the stability of excavation face. Through the three axis test, comparison analysis of the variation characteristics of soil properties and strength under different confining pressure before and after grouting. The study found that the mud film forming process, will make the sand cohesion and internal friction angle increases and decreases as the confining pressure increases, the strength of soil will increase;
(2) the excavation surface active damage factors. Through the indoor model test of different slurry ratio, soil thickness, the comparative study of excavation surface active destruction the head height and soil properties and other conditions. The research results show that the thickness of the overlying soil and water head height of excavation face stability is affected with soil thickness increase the excavation face support force increases gradually; during the process of excavation and seepage in pore water pressure changes will reduce the stability of the excavation face; from the initial excavation to the instability of the whole process of change, there are soil arching phenomenon, this phenomenon in the dry sand tests become more and more obvious. Influencing factors of excavation face stability, in addition to the soil arch effect, more important is the internal friction angle, soil thickness and height of water head;
(3) water splitting effect research. In the process of shield tunneling construction, slurry pressure is set too high will lead to slurry splitting. Resulting slurry cabin pressure dropped sharply, the instability of the excavated surface. Through indoor model test, the same for different slurry ratio, soil thickness, water head height and soil properties and other conditions under the water splitting phenomenon are studied. The results show that the splitting ratio of slurry pressure and mud, closely related to head height and soil properties, the number of mud fracturing pressure is significantly higher than the number of mud; splitting required fracturing pressure and time is higher than that of water occurs when water means in the formation of saturation more prone to splitting; soil gradation, cohesion and angle of internal friction properties directly affect the water splitting effect, fracturing pressure is higher than that in coarse sand slurry;
(4) study on face stability evaluation method of excavation face excavation. The traditional failure mainly refers to the active and passive sliding. The indoor model tests show that in the sand, splitting failure occurs more easily than passive sliding under the pressure of high mud slurry, therefore recommended excavation supporting upper surface passive failure stress value should be in the mud fracturing pressure shall prevail. In addition, through theoretical calculation, put forward suitable for sandy soil excavation face failure correction coefficient method to judge steady stability;
(5) supporting force calculation method. Through theoretical calculation, analysis of the current commonly used supporting force formula, and the applicability of the Japanese experience formula is verified by examples. In addition, the excavation in tunnel excavation of permeable sand bed slurry supporting force value of the parameter analysis, a shield the construction experience of excavation supporting force of slurry water branch of facial formula is given in sand soil layer shallow overburden tunnel supporting force is safer than the range of 1.38-2.14.

【學(xué)位授予單位】：北京交通大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：U455.43

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