發(fā)布時間：2018-07-20 12:38

【摘要】：我國長江流域及沿海地區(qū)多為軟土平原地區(qū),這些地區(qū)土質承載力低、地下水位高,容易發(fā)生基坑失穩(wěn)事故,基坑隆起是基坑失穩(wěn)的常見形式之一。在深基坑工程安全評估中,深基坑坑底抗隆起破壞分析具有重要參考價值,同時也是基坑工程設計中的一項重要內容。深基坑坑底抗隆起穩(wěn)定性分析方法主要有三種：極限平衡法、極限分析法和數值分析法。 本文以極限平衡法中的圓弧滑動模式為理論基礎,認為現有圓弧滑動簡化公式應考慮分層土的土體參數、擋墻參數以及加固土參數的影響,提出了考慮這三類影響因素的深基坑坑底抗隆起穩(wěn)定性安全系數計算公式,并通過力矩相等原則推導了等效土體參數的取值方法。同時,分析了圓弧滑動模式和極限承載力模式計算公式的適用條件。通過對工程實例的計算,驗證了不同公式在不同條件下的適用性和準確性。然后,對Prandtl極限承載力模式計算公式及圓弧滑動模式公式,利用MATLAB進行編程,把土體參數、擋墻參數以及加固土參數對深基坑坑底抗隆起穩(wěn)定性的影響程度進行對比分析。最后,通過極限承載力模式結合Vesic理論,推導了存在軟弱下臥層深基坑坑底抗隆起穩(wěn)定安全系數計算公式,并提出了可以不考慮軟弱下臥層影響的臨界厚度概念,分析了不同參數影響下臨界厚度的大小。得到以下幾項主要研究成果： (1)本文推導公式與國家規(guī)范公式對比,考慮了基坑內外主被動土壓力系數的區(qū)別、加固土的影響以及擋墻提供彎矩的作用,并詳細推導了等效土體參數的取值方法。通過工程算例,分析對比了本文推導公式與其他公式計算結果的區(qū)別。當擋墻底部以上土質較差時,本文推導公式比Prandtl極限承載力模式公式更加合理。 (2)在深基坑坑底抗隆起穩(wěn)定性各影響因素中,土體內聚力、土體內摩擦角及土體重度和擋墻插入比對深基坑坑底抗隆起穩(wěn)定性影響很大。通過計算分析對比,各參數影響程度從大到小排序為：土體內摩擦角,土體重度,土體內聚力,擋墻插入比,加固土無側限抗壓強度,地面超載。 (3)在分析存在軟弱下臥層的基坑坑底抗隆起穩(wěn)定性時,當擋墻底部離軟弱下臥層頂部的厚度小于臨界厚度時,需要考慮軟弱下臥層對基坑抗隆起穩(wěn)定性的影響；當擋墻底部離軟弱下臥層頂部的厚度大于臨界厚度時,可不考慮軟弱下臥層對基坑抗隆起穩(wěn)定性的影響。
[Abstract]:The Yangtze River Basin and the coastal area are mostly soft soil plain area. The soil bearing capacity is low and the groundwater level is high, the foundation pit instability is easy to occur. The foundation pit bulge is one of the common forms of the foundation pit instability. In the safety assessment of deep foundation pit engineering, the analysis of the foundation pit bottom anti uplift failure is of important reference value, and it is also a foundation pit. There are three main methods for analyzing the uplift stability of deep foundation pit bottom: limit equilibrium method, limit analysis method and numerical analysis method.
Based on the theory of circular arc sliding mode in the limit equilibrium method, this paper considers that the existing simplified formula of circular arc sliding should take into account the soil parameters of the layered soil, the parameters of the retaining wall and the influence of the reinforced soil parameters. The formula for calculating the safety factor of the stability of the bottom of the deep foundation pit with these three factors is considered, and the original moment is equal to the original moment. The method of obtaining the equivalent soil parameters is derived. At the same time, the applicable conditions for the calculation formula of the circular arc sliding mode and the ultimate bearing capacity model are analyzed. The applicability and accuracy of the different formulas under different conditions are verified by the calculation of the engineering examples. Then, the calculation formula of the Prandtl extreme limit bearing capacity model and the circular slip mode are given. The formula is programmed with MATLAB. The influence degree of soil parameters, retaining wall parameters and reinforcement parameters on the stability of deep foundation pit at the bottom of the pit is compared and analyzed. Finally, the calculation formula of stability safety factor for the foundation pit bottom of deep foundation pit with weak substratum is derived through the ultimate bearing capacity model and the Vesic theory. The critical thickness can be considered without consideration of the influence of soft substratum, and the critical thickness under the influence of different parameters is analyzed.
(1) the comparison between the derived formula and the national standard formula, the difference between the dynamic soil pressure coefficient of the main ground inside and outside of the foundation pit, the effect of reinforcement soil and the effect of the retaining wall providing bending moment, and the value method of the equivalent soil parameters are derived in detail. The difference between the derived formula and the calculation results of the other formulas is analyzed and compared by an engineering example. When the soil quality above the bottom of the retaining wall is poor, the formula deduced in this paper is more reasonable than the formula of Prandtl ultimate bearing capacity formula.
(2) among the factors affecting the stability of the deep foundation pit, the cohesive force, the friction angle of the soil and the gravity of the soil and the insertion of the retaining wall have a great influence on the stability of the bottom of the deep foundation pit. By the calculation and analysis, the degree of influence of the parameters from the large to small is the internal friction angle, the soil mass, the cohesive force of the soil and the retaining wall. The insertion ratio has no unconfined compressive strength of the reinforced soil, and the ground is overloaded.
(3) when analyzing the stability of foundation pit bottom in soft substratum, when the thickness of the bottom of the retaining wall is less than the critical thickness at the top of the weak substratum, it is necessary to consider the influence of the soft substratum on the stability of the foundation pit against the bulge. The effect of lying layer on the stability of foundation pit anti uplift.
【學位授予單位】：武漢理工大學
【學位級別】：碩士
【學位授予年份】：2013
【分類號】：TU473.2

【參考文獻】

相關期刊論文 前10條

1 丁春林;;軟土地區(qū)承壓水基坑突涌穩(wěn)定計算法研究綜述[J];地下空間與工程學報;2007年02期

2 占學釗;;深基坑坑底土體抗隆起穩(wěn)定性的驗算方法辨析[J];地下工程與隧道;2011年03期

3 李平;楊挺;王義;陳育民;;基坑工程隆起變形研究綜述[J];河海大學學報(自然科學版);2010年02期

4 沈健;王衛(wèi)東;王建華;;深基坑工程考慮時空效應的計算方法研究[J];建筑結構;2007年05期

5 馬琳琳;;淺談基坑穩(wěn)定性分析[J];山西建筑;2011年08期

6 張震;馮虎;劉國彬;;基坑抗隆起穩(wěn)定三維分析的極限平衡法[J];沈陽建筑大學學報(自然科學版);2012年01期

7 吉茂杰,劉國彬;開挖卸荷引起地鐵隧道位移預測方法[J];同濟大學學報(自然科學版);2001年05期

8 胡展飛,周健,楊林德;深基坑基底軟土穩(wěn)定性研究[J];土木工程學報;2001年02期

9 王桂平;劉國彬;;考慮時空效應的軟土深基坑變形有限元分析[J];土木工程學報;2009年04期

10 黃茂松;余生兵;秦會來;;基于上限法的K_0固結黏土基坑抗隆起穩(wěn)定分析[J];土木工程學報;2011年03期

相關碩士學位論文 前6條

1 趙伯霖;基于FLAC3D地鐵車站深基坑變形規(guī)律研究[D];河北工程大學;2011年

2 門燕青;各向異性軟土深基坑坑底抗隆起穩(wěn)定性分析[D];山東科技大學;2011年

3 肖堅;軟土地區(qū)基坑開挖穩(wěn)定性分析[D];華中科技大學;2005年

4 王立新;基坑工程施工階段的破壞機制及應急預案研究[D];鄭州大學;2007年

5 宋曉宇;考慮強度各向異性的軟土基坑抗隆起穩(wěn)定性上限分析[D];同濟大學;2007年

6 徐林;基坑尺寸效應的有限元分析[D];天津大學;2007年

，

本文編號：2133538