本文選題：真空預(yù)壓 + 硬殼層��； 參考：《天津大學(xué)》2015年博士論文

【摘要】：隨著沿海城市建設(shè)及對外開放的需要,圍海造陸已成為沿海工程建設(shè)和海岸開發(fā)工程中的重要組成部分。在天津、深圳、廣州等沿海軟土地區(qū),圍海造陸的方式一般是在原地面上吹填一層吹填土,通過真空預(yù)壓加固,形成可以作為建筑地基使用的陸域。隨著圍海造陸工程向海域延伸,需要吹填的泥層厚度不斷增加,使得傳統(tǒng)真空預(yù)壓工藝已經(jīng)不能滿足工程要求,需要提出新的工藝。同時,真空預(yù)壓對吹填土的作用效果與對天然沉積的土層的效果有很大差別,用傳統(tǒng)固結(jié)理論計(jì)算的吹填土在真空壓力作用下的固結(jié)度與吹填土實(shí)際的固結(jié)度有很大差別,因此有必要建立計(jì)算吹填土在真空預(yù)壓作用下的固結(jié)度的新方法。傳統(tǒng)的真空預(yù)壓工藝需要大量的中粗砂,而天津地區(qū)的砂源非常匱乏,需要開發(fā)不用或少用砂料的真空預(yù)壓工藝。針對這些問題,本文進(jìn)行了比較系統(tǒng)的研究,主要研究內(nèi)容和取得的成果如下:(1)新近吹填的吹填土的承載力很低,在深厚吹填土上面形成打設(shè)排水板機(jī)械的工作層是制約真空預(yù)壓工期的主要因素之一。本課題根據(jù)室內(nèi)模型試驗(yàn)和魏西克(Vesic)雙層地基承載力計(jì)算公式,提出了在吹填土表面吹填一定厚度的粉細(xì)砂形成硬殼層的方法,可以快速形成一個硬殼層,其承載力能夠滿足打設(shè)排水板機(jī)械的承載力要求,解決了這個工程難題。該工藝和推薦的硬殼層的厚度(0.6-0.8m)已在天津?yàn)I海新區(qū)圍海造陸工程中得到廣泛應(yīng)用,大大節(jié)省了施工工期,降低了工程造價,加快了吹填土加固的施工進(jìn)度。(2)通過模型試驗(yàn)?zāi)M了高含水量吹填土在水土分離、插板期間、真空預(yù)壓期間的沉降過程,從而可以比較準(zhǔn)確地計(jì)算出吹填土在水土分離階段、插板期和真空預(yù)壓階段的沉降量,可以為吹填造陸工程提供合理的吹填標(biāo)高建議,避免由于吹填量過多或過少引起的浪費(fèi)和工程問題。(3)模型試驗(yàn)和現(xiàn)場實(shí)際工程的觀測數(shù)據(jù)表明,采用傳統(tǒng)的固結(jié)理論計(jì)算的吹填土固結(jié)度與實(shí)測值有很大的差距。本課題首先研究了該問題的機(jī)理,即靠近排水板和地表的土體,由于排水路徑短,有效應(yīng)力增加較快而導(dǎo)致滲透性降低,阻礙了較遠(yuǎn)處土體的排水通路,進(jìn)而使得土體的整體固結(jié)速率下降。在此基礎(chǔ)上建立了變固結(jié)系數(shù)的固結(jié)方程,并提出了方程的數(shù)值解法。該成果對于正確評估經(jīng)真空預(yù)壓處理的吹填土地基的固結(jié)程度和不均勻性有重要意義。(4)提出了用砂量較小的二次吹泥自密封真空預(yù)壓加固吹填土的工藝,該方法不僅可以解決天津地區(qū)砂源匱乏的問題,而且使真空預(yù)壓技術(shù)更加經(jīng)濟(jì)、環(huán)保。泥密封通過直排式真空預(yù)壓模型試驗(yàn)的研究可以發(fā)現(xiàn),該工藝在加固效果上達(dá)到了真空預(yù)壓加固的目的,加固效果較好,可以進(jìn)行現(xiàn)場的中試工作,以完善大面積的真空預(yù)壓施工工藝。本文根據(jù)非飽和土力學(xué)中收縮膜的概念,從微觀角度,分析了在這種工藝加固過程中土體的開裂問題。通過分析收縮膜在基質(zhì)吸力、水膜張力和周圍邊界傳遞的拉力的平衡條件,建立了收縮膜的受力模型;通過水膜與附著物的張力試驗(yàn)類比了土體開裂過程中收縮膜的張拉作用;通過不同尺度和形狀的模型槽試驗(yàn)研究了飽和土在干燥和蒸發(fā)條件下裂縫發(fā)生、發(fā)展和終止的過程。研究結(jié)果可加深對土體開裂機(jī)理的認(rèn)識水平,并在直排式真空預(yù)壓工藝中得到應(yīng)用。(5)本文應(yīng)用ABAQUS軟件對復(fù)雜應(yīng)力路徑的吹填土加固過程進(jìn)行模擬,分析了淺層人工插板、一次真空預(yù)壓、吹砂鋪膜、深層插板、二次真空預(yù)壓、填土堆載、真空-堆載預(yù)壓等施工全過程中吹填土的應(yīng)力變化,通過有限元中均布荷載、超孔壓、真空度等加荷方式模擬土體中的應(yīng)力狀態(tài),并計(jì)算在外荷載作用下的土體固結(jié)沉降,實(shí)測結(jié)果與計(jì)算結(jié)果吻合較好。數(shù)值計(jì)算時不僅考慮土體滲透系數(shù)隨孔隙比變化的影響,而且真實(shí)模擬了真空載荷與堆載隨時間的梯度變化,更符合真實(shí)情況。最后通過分析不同的工況作業(yè)時間對吹填土沉降影響,得出,延長插板時間不能改變土體的總體沉降,但可以減少深層抽真空時間,節(jié)約能源。(6)通過吹填土自重固結(jié)試驗(yàn)的研究發(fā)現(xiàn),在吹填土自然晾曬初期,土體的蒸發(fā)速率與純水的蒸發(fā)速度相當(dāng)。在無降水情況下,表層20cm厚度土體會在2個月內(nèi)形成硬層,此時表層土體的含水量降低至50%以下,隨后土體的蒸發(fā)速率、沉降速率都減慢。應(yīng)用土力學(xué)三相性質(zhì)關(guān)系,得出土體含水量變化與土體沉降間的規(guī)律,并通過一維自重固結(jié)現(xiàn)場試驗(yàn),得到不同深度土體含水量的發(fā)展趨勢,完善了現(xiàn)有一維固結(jié)理論中對含水量變化關(guān)系的研究。根據(jù)現(xiàn)場數(shù)據(jù)擬合,可以預(yù)測未來時刻土體的含水量沿深度變化。研究結(jié)果為天津臨港工業(yè)區(qū)圍海造陸工程的吹填標(biāo)高的計(jì)算提供理論依據(jù),并能以此來安排施工進(jìn)度。
[Abstract]:With the construction of coastal cities and the need of opening to the outside world, the land reclamation has become an important part of coastal engineering construction and coastal development project. In Tianjin, Shenzhen, Guangzhou and other coastal soft soil areas, the way of reclamation in the sea is generally to fill a layer of dredger fill in the original ground and be reinforced by vacuum preloading to form a building site. The land area used by the base. As the sea reclamation project extends to the sea area, the thickness of the mud layer needs to be continuously increased, which makes the traditional vacuum preloading process can not meet the requirements of the project and requires a new process. At the same time, the effect of vacuum preloading on the dredger fill is very different from that of the naturally deposited soil, with the traditional consolidation. It is necessary to establish a new method to calculate the degree of consolidation of the dredger soil under vacuum preloading. The traditional vacuum preloading process requires a large amount of coarse sand, while the sand source in Tianjin is very scarce and needs not to be developed. In view of these problems, this paper makes a comparative systematic study on these problems. The main research contents and achievements are as follows: (1) the loading capacity of the newly filled and filled dredger fill is very low, and the formation of the working layer on the deep fill soil is one of the main factors that restrict the vacuum preloading period. Based on the indoor model test and the calculation formula of the bearing capacity of the Vesic double layer foundation, the paper puts forward a method of forming a hard shell layer with a certain thickness of fine sand on the surface of the dredger fill, which can quickly form a hard shell. The bearing capacity of the hard shell can meet the bearing capacity requirements of the drainage plate machinery, and the engineering problem is solved. The thickness (0.6-0.8m) of the hard shell layer (0.6-0.8m) has been widely used in the surround sea reclamation project in Binhai New Area, which has greatly saved the construction period, reduced the cost of the project and accelerated the construction progress of the reinforcement of the dredger. (2) through the model test, the high water content blows are simulated during the soil and water separation, during the plugged plate and during the vacuum preloading period. The settlement process can be used to accurately calculate the settlement of the dredger fill in the stage of soil and water separation, the plugged stage and the vacuum preloading stage. It can provide a reasonable proposal for the blow filling elevation for the land reclamation project, and avoid the waste and engineering questions caused by too much or too little blow filling. (3) the model test and the observation of the actual project in the field. It is shown that there is a big gap between the consolidation degree calculated by traditional consolidation theory and the measured value. This topic first studies the mechanism of this problem, that is, the soil near the drain board and the surface of the earth, because the drainage path is short and the effective stress increases rapidly, which leads to the permeability reduction, which hinders the drainage path of the soil in the far distance, and thus makes it possible. The consolidation rate of the soil is reduced. On this basis, the consolidation equation of the coefficient of consolidation is established, and the numerical solution of the equation is proposed. The results are of great significance for the correct assessment of the degree of consolidation and the inhomogeneity of the fill foundation treated by vacuum preloading. (4) a self sealed vacuum preloading with two sands with less sand is proposed. The technology of reinforcing the dredger fill can not only solve the problem of the shortage of sand source in Tianjin, but also make the vacuum preloading technology more economical and environmentally friendly. Through the study of the model test of the vacuum preloading through the straight row vacuum preloading, it can be found that this process has achieved the purpose of strengthening the vacuum preloading, and the reinforcement effect is better and can be carried out. According to the concept of the shrinkage film in the unsaturated soil mechanics, this paper analyzes the problem of soil cracking in the process of strengthening this process in the light of the concept of shrinkage film in the unsaturated soil mechanics, and establishes the balance condition of the tension of the contraction film in the matrix suction, the water film tension and the surrounding boundary. The stress model of the shrinkable film is made. The tensile test of the shrinkage film in the process of soil cracking is analogized by the tension test of the water film and the attachment. The process of cracking, development and termination of the saturated soil under the conditions of drying and evaporation is studied by the model groove test of different scales and shapes. The results can deepen the recognition of the mechanism of soil cracking. It is applied in the horizontal vacuum preloading process. (5) in this paper, the ABAQUS software is used to simulate the reinforcement process of the complicated stress path. The shallow layer artificial plugged plate, the first vacuum preloading, the sand blowing, the deep sanding, the two vacuum preloading, the fill loading, the vacuum loading preloading and so on are analyzed. The stress state of the soil is simulated by means of uniformly distributed load, super pore pressure and vacuum degree in the finite element method, and the consolidation settlement of soil under the external load is calculated. The measured results are in good agreement with the calculated results. The numerical calculation not only considers the influence of the soil permeability coefficient with the change of the pore ratio, but also the real simulation. The change of vacuum load and load with time gradient is more in line with the real situation. Finally, through the analysis of the effect of different working working hours on the settlement of the dredger fill, it is concluded that the extension of the plate time can not change the overall settlement of the soil, but can reduce the deep vacuum time and save the energy source. (6) through the study of the self consolidation test of the dredger fill, the study found that In the early stage of natural air drying, the evaporation rate of soil is equal to the evaporation rate of pure water. In the case of no precipitation, the surface 20cm thickness of the soil will form a hard layer within 2 months. At this time the water content of the surface soil is reduced to less than 50%, and the evaporation rate and settling rate of the soil are slowed down. The law of body water content change and soil settlement, and through one dimensional self weight consolidation field test, the development trend of soil moisture content in different depths is obtained. The relationship between water content and water content in the existing one-dimensional consolidation theory is perfected. According to the field data fitting, it can be used to predict the water content along the depth of the soil in the non coming time. The results provide a theoretical basis for the calculation of dredger fill elevation in Tianjin Lingang industrial area, and can be used to arrange the construction progress.
【學(xué)位授予單位】：天津大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2015
【分類號】：TU472.33

【相似文獻(xiàn)】

相關(guān)期刊論文 前10條

1 婁炎,楊守華,高長勝;對真空預(yù)壓加固中沉降穩(wěn)定標(biāo)準(zhǔn)的討論[J];中國港灣建設(shè);2004年01期

2 姜增國,劉伏成,姚志安;真空預(yù)壓加固軟基的變形監(jiān)測結(jié)果分析[J];武漢理工大學(xué)學(xué)報;2005年11期

3 馬云勇;張波;汪輝;;真空預(yù)壓加固軟基先導(dǎo)段現(xiàn)場試驗(yàn)研究[J];山西建筑;2008年31期

4 陳小勇;洪桂堂;;真空預(yù)壓加固橋頭軟基的施工方法及應(yīng)用[J];山西建筑;2011年02期

5 單彥賢;焦華麗;;真空預(yù)壓加固軟基的影響范圍研究[J];公路交通科技(應(yīng)用技術(shù)版);2011年02期

6 張偉帆;;沿海蠔塘回填區(qū)地基真空預(yù)壓加固效果分析[J];山西建筑;2011年12期

7 周治釗;肖明貴;吳名江;;軟土真空預(yù)壓加固設(shè)計(jì)的沉降系數(shù)法[J];路基工程;2011年02期

8 曹永華;李衛(wèi);劉天韻;;淺層超軟土地基真空預(yù)壓加固技術(shù)[J];巖土工程學(xué)報;2011年S1期

9 盧勇正,李樹國,張力霆;改善真空預(yù)壓加固效果的試驗(yàn)研究[J];河北工程技術(shù)高等�？茖W(xué)校學(xué)報;1999年01期

10 梁志榮;李忠誠;翁鑫榮;;軟土地基真空預(yù)壓加固對周圍環(huán)境的變形影響分析[J];巖土工程學(xué)報;2013年S2期

相關(guān)會議論文 前4條

1 王海鵬;唐彤芝;倪洪波;平克磊;黃鵬飛;;真空預(yù)壓加固區(qū)域邊界變形規(guī)律研究[A];工程排水與加固技術(shù)理論與實(shí)踐——第七屆全國工程排水與加固技術(shù)研討會論文集[C];2008年

2 葉柏榮;;真空預(yù)壓加固法的發(fā)展及工程實(shí)錄[A];海峽兩岸土力學(xué)及基礎(chǔ)工程地工技術(shù)學(xué)術(shù)研討會論文集[C];1994年

3 夏玉斌;王劍平;唐元松;;椒江污水處理工程超深軟基真空預(yù)壓加固效果綜合分析[A];第七屆全國工程地質(zhì)大會論文集[C];2004年

4 朱群峰;高長勝;楊守華;張凌;李東兵;;低位真空預(yù)壓加固大面積吹填淤泥地基試驗(yàn)研究[A];工程排水與加固技術(shù)理論與實(shí)踐——第七屆全國工程排水與加固技術(shù)研討會論文集[C];2008年

相關(guān)博士學(xué)位論文 前2條

1 郭炳川;真空預(yù)壓加固新近吹填土新工藝及機(jī)理研究[D];天津大學(xué);2015年

2 岑仰潤;真空預(yù)壓加固地基的試驗(yàn)及理論研究[D];浙江大學(xué);2003年

相關(guān)碩士學(xué)位論文 前6條

1 嚴(yán)露;真空預(yù)壓加固軟基固結(jié)及滲流計(jì)算理論研究[D];浙江大學(xué);2011年

2 馮偉騫;低位真空預(yù)壓加固技術(shù)應(yīng)用研究[D];天津大學(xué);2010年

3 吳仕帆;真空預(yù)壓加固吹填土地基有限元分析及室內(nèi)模擬試驗(yàn)研究[D];天津大學(xué);2009年

4 樓永良;真空預(yù)壓加固深厚軟土地基現(xiàn)場試驗(yàn)與設(shè)計(jì)理論研究[D];浙江大學(xué);2005年

5 趙陽陽;真空預(yù)壓加固對新近吹填軟粘土地基水平向變形影響范圍研究[D];天津大學(xué);2012年

6 韓飚;真空預(yù)壓加固機(jī)理及工程應(yīng)用研究[D];天津大學(xué);2010年

，

本文編號：1912286