本文選題：泥水盾構(gòu) + 超挖��； 參考：《南京大學(xué)》2014年碩士論文

【摘要】：大直徑泥水盾構(gòu)具有廣泛的地層適宜性,適合修建長距離、大斷面、高水壓下的隧道,它的這種特性使其成為興建越江、跨海隧道的最佳選擇。采用數(shù)值模擬方法對(duì)大直徑泥水盾構(gòu)掘進(jìn)進(jìn)行研究,可以給出隧道施工期間地層位移的發(fā)展變化規(guī)律,對(duì)于保護(hù)隧道附近建筑物及重要地下管線具有積極意義。該方法具有低成本、高效率的特點(diǎn),隨著計(jì)算機(jī)性能的增強(qiáng)以及數(shù)值模擬軟件的發(fā)展,有廣闊的應(yīng)用前景。 本文依托南京緯七路長江隧道工程,對(duì)右線隧道起始段盾構(gòu)掘進(jìn)過程中的若干實(shí)時(shí)監(jiān)測數(shù)據(jù)進(jìn)行了分析,并采用巖土工程分析軟件PLAXIS3D對(duì)盾構(gòu)掘進(jìn)過程進(jìn)行了模擬,得出以下結(jié)論： (1)大直徑泥水盾構(gòu)的超挖是導(dǎo)致地表沉降過大的主要因素。結(jié)合盾構(gòu)掘進(jìn)參數(shù)、開挖土體的含水率、比重,通過對(duì)開挖干土量的計(jì)算,可以粗略估算超大直徑泥水盾構(gòu)的平均超挖量,雖然有一定誤差,但結(jié)果具有一定的參考價(jià)值。 (2)采用剛度遷移法模擬盾構(gòu)掘進(jìn)時(shí),若按照盾殼的實(shí)際尺寸建立有限元模型,計(jì)算得到的地表沉降誤差非常大,所得沉降發(fā)展曲線與實(shí)測沉降發(fā)展曲線相差很大；而采用等效面收縮法模擬土體超挖時(shí),沉降計(jì)算結(jié)果與實(shí)測值比較接近,且所得沉降發(fā)展曲線與實(shí)測規(guī)律比較接近。這表明采用等效面收縮法模擬超大直徑泥水盾構(gòu)的掘進(jìn)過程是更加合理的。 (3)PLAXIS3D中的土體硬化模型,由于采用了三軸加載剛度E50、三軸卸載剛度Eur和固結(jié)儀加載剛度Eoed三個(gè)剛度參數(shù)來考慮加載、卸載的區(qū)別和土體的硬化特性,在模擬隧道開挖問題方面有一定的優(yōu)勢。對(duì)于淤泥質(zhì)粉質(zhì)粘土,在無法取得其剛度參數(shù)時(shí),可以用勘察報(bào)告中提出的壓縮模量近似作為100kPa參考?jí)合碌腅so,并將三個(gè)剛度參數(shù)按1：1：3的比例取值。這種情況下的計(jì)算結(jié)果是具有一定參考價(jià)值的。 (4)在采用剛度遷移法模擬盾構(gòu)掘進(jìn)時(shí),整體開挖與逐環(huán)開挖相比,得到的沉降量明顯偏小,二者計(jì)算所得的土體應(yīng)力重布情況差別很小。
[Abstract]:Large diameter mud shield is suitable for constructing long distance, large section and high water pressure tunnel, which makes it the best choice to build cross river tunnel and cross sea tunnel.The numerical simulation method is used to study the large-diameter mud water shield tunneling. The development and variation law of the stratum displacement during the tunnel construction can be given, which is of positive significance for the protection of the buildings near the tunnel and the important underground pipelines.This method has the characteristics of low cost and high efficiency. With the enhancement of computer performance and the development of numerical simulation software, it has a broad application prospect.In this paper, based on the Yangtze River tunnel project of Nanking Weiqi Road, some real time monitoring data during shield tunneling in the starting section of right line tunnel are analyzed, and the process of shield tunneling is simulated by using geotechnical engineering analysis software PLAXIS3D.Draw the following conclusions:1) the overexcavation of large diameter mud shield is the main factor that causes the surface subsidence to be too large.Combined with shield tunneling parameters, water content and specific gravity of excavated soil mass, the average overdigging amount of super-diameter mud shield can be roughly estimated by calculating the amount of dry soil excavated. Although there are certain errors, the results are of certain reference value.2) when using stiffness transfer method to simulate shield tunneling, if the finite element model is established according to the actual size of shield shell, the calculated surface subsidence error is very large, and the settlement development curve is very different from the measured settlement development curve.When the equivalent surface shrinkage method is used to simulate soil overexcavation, the settlement calculation results are close to the measured values, and the settlement development curve is close to the measured results.It shows that it is more reasonable to use equivalent surface shrinkage method to simulate the driving process of super diameter mud water shield.Due to the use of three stiffness parameters such as triaxial loading stiffness E50, triaxial unloading stiffness Eur and consolidation instrument loading stiffness Eoed, the difference between loading and unloading and the hardening characteristics of soil are considered.It has some advantages in simulating tunnel excavation.For silty silty clay, when the stiffness parameters can not be obtained, the compression modulus proposed in the survey report can be used as the reference pressure of 100kPa, and the three stiffness parameters can be calculated according to the 1:1:3 ratio.In this case, the calculation results are of certain reference value.4) in the simulation of shield tunneling by stiffness transfer method, the settlement obtained by the whole excavation is obviously smaller than that by the circular excavation, and the difference between the soil stress redistribution calculated by the two methods is very small.
【學(xué)位授予單位】：南京大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：U455.43;P642.26

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本文編號(hào)：1755880