本文選題：深基坑　切入點：雙排樁　出處：《中國地質(zhì)大學(xué)(北京)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：隨著城市建設(shè)的推進(jìn)與深基坑工程向縱深發(fā)展,新的支護(hù)形式不斷涌現(xiàn)。雙排樁支護(hù)方法因其在復(fù)雜工程條件下較好的適用性得到廣泛的應(yīng)用和認(rèn)可,已經(jīng)成為基坑支護(hù)的重要方法之一�？紤]到目前基坑支護(hù)理論研究落后于工程實踐的現(xiàn)狀,以及深基坑工程事故頻發(fā)、支護(hù)設(shè)計過于保守造成浪費等現(xiàn)象,本文針對深基坑支護(hù)穩(wěn)定性的理論及驗證方法進(jìn)行了進(jìn)一步探索。本文主要的研究內(nèi)容及分析結(jié)果如下:(1)對工程現(xiàn)場勘察資料進(jìn)行整理,根據(jù)勘察結(jié)果區(qū)分土層,并進(jìn)行各參數(shù)數(shù)據(jù)分類統(tǒng)計,根據(jù)統(tǒng)計結(jié)果描繪出各參數(shù)的分布規(guī)律,研究發(fā)現(xiàn)對于不同土層中的粘聚力、內(nèi)摩擦角和重度均大致復(fù)合正態(tài)分布規(guī)律;(2)建立了深基坑雙排樁支護(hù)的FLAC3D數(shù)值計算模型,根據(jù)實際工程狀況確定模型的邊界條件、初始條件與模型參數(shù),合理布置支護(hù)樁,分步開挖計算。計算結(jié)果表明:在現(xiàn)場工況下進(jìn)行雙排樁支護(hù),基坑開挖后可以最終達(dá)到穩(wěn)定狀態(tài);基坑開挖后主應(yīng)力跡線及大小均會發(fā)生變化,坡腳應(yīng)力集中明顯;越靠近開挖面頂部水平位移越大,豎向最大位移發(fā)生在距坡面一定距離處;排樁可改善周圍區(qū)域土體的應(yīng)力狀況,制約土體變形;后排樁的支護(hù)效果大于前排樁;(3)根據(jù)數(shù)值計算結(jié)果圖像確定出基坑坡后土體的可能滑動面,對滑動面曲線進(jìn)行擬合并確定其數(shù)學(xué)表達(dá)式,根據(jù)條分法給出了計算坡后土體抗滑穩(wěn)定性的公式;(4)采用Monte-Carlo可靠性方法,以輸入?yún)?shù)的概率分布為基礎(chǔ),建立起分析基坑失效概率的計算模型并編制相應(yīng)計算程序。將實際工況下的大量計算結(jié)果進(jìn)行統(tǒng)計分析發(fā)現(xiàn):由穩(wěn)定性計算公式得到的大量計算值的概率密度大致服從正態(tài)分布;由累積概率曲線可知,該工況下基坑土體達(dá)到抗滑穩(wěn)定的概率為98%,支護(hù)滿足安全要求;(5)通過對不同土層、各個參數(shù)對計算結(jié)果的影響研究發(fā)現(xiàn):各個參數(shù)中內(nèi)摩擦角對土體穩(wěn)定性的影響最大;不同土層各參數(shù)對穩(wěn)定性的影響不同,其中粉質(zhì)黏土影響要大于淤泥質(zhì)黏土;土的重度對計算結(jié)果影響不大。
[Abstract]:With the advance of urban construction and the development of deep foundation pit engineering, new support forms are emerging constantly. The double row pile support method has been widely used and approved because of its good applicability in complex engineering conditions. It has become one of the important methods of foundation pit support. Considering the fact that the research of foundation pit support theory lags behind the engineering practice at present, and the accidents of deep foundation pit engineering occur frequently, the support design is too conservative and causes waste, etc. In this paper, the theory and verification method of supporting stability of deep foundation pit are further explored. The main research contents and analysis results of this paper are as follows: 1. According to the statistical results, the distribution law of each parameter is described, and the cohesive force in different soil layers is found. The FLAC3D numerical calculation model of double-row pile support in deep foundation pit is established. The boundary conditions, initial conditions and model parameters of the model are determined according to the actual engineering conditions, and the supporting piles are reasonably arranged. The calculation results show that the stability of foundation pit can be achieved after excavation, the main stress trace and size will change after excavation, and the stress concentration of slope foot will be obvious. The bigger the horizontal displacement is near the top of the excavated surface, the greater the vertical maximum displacement occurs at a certain distance from the slope surface, and the pile row can improve the stress condition of soil in the surrounding area and restrict the deformation of soil. The supporting effect of the back row pile is better than that of the front row pile. According to the image of the numerical calculation results, the possible sliding surface of the soil after the foundation pit slope is determined, and the mathematical expression of the sliding surface curve is determined by the pseudo combination of the sliding surface curve. According to the slice method, the formula for calculating the anti-slide stability of soil after slope is given. The Monte-Carlo reliability method is adopted, and the probability distribution of input parameters is used as the basis. The calculation model of the failure probability of foundation pit is established and the corresponding calculation program is worked out. It is found that the probability density of a large number of calculated values obtained from the formula of stability calculation is large by statistical analysis of a large number of calculation results under actual working conditions. Induced by the normal distribution; According to the cumulative probability curve, the probability of the stability of foundation pit soil is 98 and the support meets the safety requirements. The results show that the internal friction angle has the greatest influence on the stability of soil, and the influence of different soil layer parameters on soil stability is different, and the influence of silt clay is greater than that of silt clay. The weight of soil has little effect on the calculation results.
【學(xué)位授予單位】：中國地質(zhì)大學(xué)(北京)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TU753
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本文編號：1634245