本文選題：管幕凍結(jié)工法 + 曲線管幕　； 參考：《長安大學》2015年博士論文

【摘要】：隨著我國工程建設(shè)的深入推進,出現(xiàn)了一些復雜工程如高速公路下穿正在運營的鐵路線、不停航跑道下修建地下通道、高速公路或城市道路下穿敏感建筑等。這些工程對自身施工安全和地表沉降控制提出了更高要求,管幕凍結(jié)法為解決此類復雜工程問題提供了一種新的技術(shù)思路和途徑。管幕凍結(jié)法是利用頂管設(shè)備將鋼管管節(jié)頂入土體中,各單管間的空隙采用凍結(jié)的方法進行封閉止水,在管幕及凍結(jié)圈組成的支護體系下進行土體開挖的一種施工方法,是針對曲線管幕在管幕法的基礎(chǔ)上而提出的。該工法體系中,由頂管形成的管幕作為結(jié)構(gòu)體承受主要荷載,凍結(jié)起到封水作用,防止管間的水土流失。本文以正在建設(shè)的港珠澳大橋珠海連接線項目為依托,結(jié)合拱北口岸暗挖段工程實際,采用室內(nèi)模型試驗研究了單根頂管管節(jié)偏角與管節(jié)應力變化規(guī)律,并采用室內(nèi)模型試驗和數(shù)值分析研究了管幕頂管群管間的相互影響,為曲線管幕的形成提供參考。研究了凍結(jié)止水帷幕在積極凍結(jié)期和維護凍結(jié)期的凍結(jié)效果,并對凍脹變形的影響進行了數(shù)值模擬計算分析,取得以下主要成果:1、管幕凍結(jié)法工法在技術(shù)上是可行的,可為復雜條件下的暗挖施工提供一種新的思路。2、頂進力按照經(jīng)驗公式計算時,應充分考慮各種因素對頂進力的影響。在曲線頂進過程中,頂進力的傳遞呈不對稱分布,管節(jié)應變沿軸線基本呈減小的趨勢,且管節(jié)會存在一定的偏轉(zhuǎn)。3、通過相鄰頂管相互影響的研究結(jié)果表明,后頂頂管會對先定頂管產(chǎn)生一定的影響:頂管所產(chǎn)生的沉降槽隨后頂管的頂進由先偏向頂頂管的上方向兩管中間偏移,兩頂管間的土體出現(xiàn)較大的屈服,后頂頂管會在先頂頂管上產(chǎn)生一定的附加作用力。通過控制頂管施工頂進參數(shù)控制、及時測量糾偏,管幕頂管間的相互影響作用可有效降低,可保證管幕的形成。4、在積極凍結(jié)期,僅開啟圓形凍結(jié)管可以實現(xiàn)頂管管節(jié)的封水作用,但形成設(shè)計的凍土厚度需較長時間。異形加強凍結(jié)管可明顯提高凍結(jié)效果。因此,在工程應用中建議在積極凍結(jié)期采用圓形凍結(jié)管和異形加強凍結(jié)管同步開啟方案。對長距離水平凍結(jié),建議采用分段凍結(jié)方案。5、在維護凍結(jié)期,為減少對凍結(jié)效果的影響并利于開挖斷面的施工作業(yè),開挖斷面內(nèi)空氣溫度宜控制在25℃。開挖斷面的風速對凍結(jié)效果影響不顯著,對開挖斷面的通風無需要求過嚴。6、限位管的開啟對凍結(jié)效果影響非常顯著,限位管的開啟可有效控制凍土的厚度。限位管內(nèi)流體的溫度對凍結(jié)效果影響較大,為避免洞穿現(xiàn)象并有效限制凍土厚度,限位管內(nèi)流體的溫度宜為15℃左右。7、地表最大隆起量、最大水平位移、隆起影響范圍及水平位移影響范圍隨凍土壁厚度的增加而線性增大,管幕上端、側(cè)端頂管的位移隨凍土壁厚度的增加而線性增大。因此,在工程中必須對凍土壁厚度加以控制,以免對周邊環(huán)境產(chǎn)生較大影響。8、地表最大隆起點和地表水平位移最大點的位置幾乎不隨凍土壁厚度的變化而變化,最大隆起點總是發(fā)生在地表豎直對應暗挖段中心的位置,最大水平位移總是發(fā)生在管幕側(cè)壁橫向向外5m左右所對應地面的位置附近。利用這一規(guī)律,結(jié)合地面變形監(jiān)測數(shù)據(jù),可以更有針對性的來控制地面變形。
[Abstract]:With the deepening of the construction of China's engineering, some complex projects, such as the railway lines running under the freeway, the underground passage under the runway, the sensitive buildings under the highway or the urban road, have been put forward. These projects put forward higher requirements for the safety of the construction and the control of the ground settlement, and the freezing method of the pipe curtain is solved. This kind of complex engineering problem provides a new technical idea and way. The freezing method of pipe curtain is a construction method for the excavation of soil under the supporting system composed of pipe curtain and freezing ring. The curtain is put forward on the basis of the pipe curtain method. In this system, the pipe curtain formed by the pipe roof acts as the main load, freezing up the water sealing function and preventing the water and soil loss between the pipes. This paper is based on the Zhuhai connection line project of the Hong Kong Zhuhai Macao Bridge, which is being built, and combines with the practice of the Gongbei port excavation section, and adopts the indoor model. The variation law of section angle and pipe joint stress of single pipe jacking pipe was tested and studied, and the interaction between pipe roof pipe group was studied by indoor model test and numerical analysis. It provided reference for the formation of curve pipe curtain. The freezing effect of frozen water stop curtain in active freezing period and freezing period was studied, and the effect on frost heave deformation was also studied. The numerical simulation analysis is carried out to obtain the following main achievements: 1, the pipe curtain freezing method is technically feasible, and can provide a new idea for the excavation under complex conditions,.2. When the jacking force is calculated according to the empirical formula, the influence of various factors on the jacking force should be fully considered. The transfer of the jacking force during the curve jacking process With the asymmetry distribution, the pipe joint strain decreases along the axis basically, and the pipe joint will have a certain deflection.3. Through the study of the interaction between adjacent pipe jacking, it is shown that the rear top pipe will have a certain effect on the pre fixed pipe jacking. The top pipe of the pipe jacking is followed by the top of the top pipe in the middle of the top two tubes. In the two top pipe, there is a large yield of soil, and the rear top pipe will produce a certain additional force on the top top pipe. By controlling the jacking parameters of the pipe jacking construction and measuring the deviation in time, the interaction between the pipe roof pipe can be effectively reduced, and the pipe curtain can be formed to form.4. In the active freezing period, only the circular freezing pipe is opened. The water sealing effect of pipe jacking pipe can be realized, but it takes a long time to form the designed frozen soil thickness. The frozen tube can be obviously improved by the special shape strengthening freezing pipe. Therefore, in the engineering application, it is suggested that the circular freezing tube and the special shape strengthen the freezing pipe be synchronized with the freezing pipe during the active freezing period. Scheme.5, in the maintenance of freezing period, in order to reduce the effect of freezing effect and help to excavate the construction work of the excavation section, the air temperature in the excavation section should be controlled at 25 degrees C. The wind speed of the excavation section has no significant influence on the freezing effect. The ventilation of the excavation section needs no strict.6, and the opening of the limit tube has a very significant influence on the freezing effect. The opening of the pipe can effectively control the thickness of frozen soil. The temperature of the fluid in the limit pipe has a great influence on the freezing effect. It is to avoid the penetration phenomenon and effectively limit the thickness of the frozen soil. The temperature of the fluid in the limit tube should be about 15.7, the maximum uplift of the surface, the maximum horizontal displacement, the impact range of the uplift and the horizontal displacement with the thickness of the frozen soil wall. The displacement of the upper end of the pipe curtain and the lateral end pipe increase linearly with the increase of the thickness of the frozen soil wall. Therefore, it is necessary to control the thickness of the permafrost wall in the engineering so as not to have a greater influence on the surrounding environment,.8, the maximum location of the maximum ground point of the ground and the horizontal displacement of the earth's surface almost does not vary with the thickness of the frozen soil wall. Change, the maximum long starting point always occurs at the position of the surface vertical corresponding to the center of the dark excavation section, the maximum horizontal displacement always occurs near the position of the corresponding ground at the lateral 5m of the lateral wall of the pipe curtain.

【學位授予單位】：長安大學
【學位級別】：博士
【學位授予年份】：2015
【分類號】：TU94

【參考文獻】

相關(guān)期刊論文 前1條

1 齊吉琳;馬巍;;凍土的力學性質(zhì)及研究現(xiàn)狀[J];巖土力學;2010年01期

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本文編號：1837406