本文關鍵詞： 營口軟土 物理力學特性 真三軸試驗 各向異性特征　出處：《遼寧工程技術大學》2014年碩士論文　論文類型：學位論文

【摘要】：受地質構造、應力歷史、顆粒成分等因素影響,軟土具有顯著的區(qū)域性,不同地區(qū)的軟土物理力學性質差異較大。營口地區(qū)軟土是遼寧濱海地區(qū)三角洲沖積平原形成的一種典型的粉質粘土,隨著地鐵、隧道、基坑等工程中軟土變形與強度問題越來越突出,迫切需要對營口地區(qū)軟土的物理力學特性和土體變形及強度進行深入研究,增強對營口地區(qū)軟土的認識,為實際工程提供一定的理論參考和借鑒。文章通過搜集工程地質資料,采用室內試驗與理論分析相結合的方法,開展了營口軟土力學特性的試驗研究,具體成果如下：1)對比分析了營口地區(qū)與上海、天津等地區(qū)軟土的物理力學特性,發(fā)現營口地區(qū)軟土的孔隙比、液塑限指數、飽和度等普遍偏低；統計結果表明,營口地區(qū)軟土的粘聚力比上海、天津地區(qū)的軟土偏小,而內摩擦角比天津地區(qū)軟土偏大,但略小于上海地區(qū)的軟土；無側限抗壓強度試驗測得土體的靈敏度在2-4之間,表明營口地區(qū)軟土屬于中靈敏度土；對含水量、密度等物理參數進行線性回歸擬合,并得到了該區(qū)域的線性回歸方程；采用塑性圖分析表明營口地區(qū)軟土為中、高塑性粘土。2)開展了營口地區(qū)軟土的真三軸試驗研究,分析了營口軟土各向異性的特征以及其變形和強度,結果表明：當載荷分別沿大主應力方向、中主應力方向和小主應力方向單向加載時,大主應變ε1、中主應變ε2、小主應變ε3呈現不同的變化趨勢；保持σ3不變時,土體的應力應變曲線隨b值的增加其變化趨勢變陡,變化幅度也隨之增大；隨著中主應力比b增大,土體的粘聚力和內摩擦角變化趨勢相反,前者呈先下降后上升的趨勢,后者呈先上升后出現略微下降的趨勢；在圍壓一定的條件下,隨著含水率越大,土體強度逐漸降低,從含水率為15%至25%的土體最大強度差值幅度接近35%；并通過試驗結果得到了試樣的在不同含水率下p-q平面上的臨界狀態(tài)線,都可以用直線進行較好的擬合；此外根據土體破壞時的三維應力狀態(tài)得到了在π平面上的屈服曲線,其在π平面上的屈服軌跡比較接近松崗-中井屈服準則(SMP)。3)采用歸一化的方法對真三軸的試驗結果進行了定量化分析,得到了營口地區(qū)軟土的應力應變歸一化方程,擬合結果能很好預測和評價對不同圍壓下軟土的應力應變關系；針對鄧肯-張模型不能考慮土體各向異性的不足,基于真三軸試驗結果對鄧肯-張本構模型的參數提出修正,其可以充分考慮土體各向異性的特點,并通過真三軸試驗結果驗證了該模型的可靠性和實用性。
[Abstract]:Affected by geological structure, stress history, particle composition and other factors, soft soil has a significant regional. The soft soil in Yingkou area is a typical silty clay formed in the delta alluvial plain of coastal area of Liaoning Province, along with the subway and tunnel. The problem of deformation and strength of soft soil is more and more prominent in foundation pit and so on. It is urgent to study the physical and mechanical properties of soft soil and the deformation and strength of soil in Yingkou area to enhance the understanding of soft soil in Yingkou area. Through collecting engineering geological data and adopting the method of combination of laboratory test and theoretical analysis, the paper carried out the experimental research on the mechanical properties of Yingkou soft soil. The concrete results are as follows: (1) the physical and mechanical properties of soft soil in Yingkou area are compared with those in Shanghai and Tianjin. It is found that the porosity ratio, liquid-plastic limit index and saturation of soft soil in Yingkou area are generally low. The results show that the cohesion of soft soil in Yingkou area is smaller than that in Shanghai, and the angle of internal friction is larger than that in Tianjin area, but slightly smaller than that in Shanghai area. The sensitivity of soil measured by unconfined compressive strength test is between 2-4, indicating that the soft soil in Yingkou area belongs to medium sensitive soil. The physical parameters such as water content and density were fitted by linear regression, and the linear regression equation of the region was obtained. The plastic diagram analysis shows that the soft soil in Yingkou area is medium and high plastic clay. 2) the true triaxial test of the soft soil in Yingkou area is carried out, and the anisotropy characteristics, deformation and strength of the soft soil in Yingkou area are analyzed. The results show that the main strain 蔚 _ 1, the medium principal strain 蔚 _ 2 and the small principal strain 蔚 _ 3 show different trends when the load is loaded in the direction of large principal stress, middle principal stress and small principal stress respectively. When 蟽 _ 3 is kept constant, the stress-strain curve of soil becomes steeper with the increase of b value, and the range of variation also increases. With the increase of the mid-principal stress ratio b, the cohesive force and the angle of internal friction of the soil have the opposite trend, the former shows the tendency of decreasing first and then rising, the latter shows a tendency of rising first and then slightly decreasing. Under certain confining pressure, with the increase of water content, the soil strength decreases gradually, and the maximum strength difference range from 15% to 25% is close to 35. The critical state line on p-q plane with different moisture content is obtained by the test results, which can be fitted well by straight line. In addition, according to the three-dimensional stress state of soil failure, the yield curve on 蟺 plane is obtained. The yield trajectory on 蟺 plane is close to the yield criterion SMP.3) the true triaxial test results are quantitatively analyzed by the normalized method. The stress-strain normalization equation of soft soil in Yingkou area is obtained. The fitting results can well predict and evaluate the stress-strain relationship of soft soil under different confining pressures. In view of the deficiency that Duncan-Zhang model can not consider soil anisotropy, the parameters of Duncan-Zhang Ben model are modified based on true triaxial test results, which can fully consider the characteristics of soil anisotropy. The reliability and practicability of the model are verified by the true triaxial test results.
【學位授予單位】：遼寧工程技術大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TU447

【參考文獻】

相關期刊論文 前10條

1 雷華陽;賈亞芳;李肖;;濱海軟土非線性蠕變特性的試驗研究[J];巖石力學與工程學報;2013年S1期

2 劉國清;寧國立;陳厚仲;張先宇;;武漢軟土的卸荷應力—應變歸一化特性研究[J];建筑科學;2012年03期

3 扈萍;黃茂松;馬少坤;呂璽琳;;粉細砂的三維彈塑性本構模型與試驗驗證[J];地下空間與工程學報;2011年04期

4 張坤勇;朱俊高;吳曉銘;李永紅;;復雜應力條件下摻礫黏土真三軸試驗[J];巖土力學;2010年09期

5 楊愛武;閆澍旺;杜東菊;趙瑞斌;劉舉;;堿性環(huán)境對固化天津海積軟土強度影響的試驗研究[J];巖土力學;2010年09期

6 李金柱;朱向榮;劉用海;;結構性軟土彈塑性損傷模型及其應用[J];浙江大學學報(工學版);2010年04期

7 李宏恩;李同春;田景元;李艷;李成;梁棟;;改進的鄧肯—張模型在大壩應力應變分析中的應用[J];水電能源科學;2010年03期

8 王成;張延軍;倪金;李錄娟;;營口地區(qū)軟土狀土研究[J];中國水運(下半月);2010年01期

9 陳景濤;馮夏庭;;高地應力下硬巖的本構模型研究[J];巖土力學;2007年11期

10 孫紅,袁聚云,趙錫宏;軟土的真三軸試驗研究[J];水利學報;2002年12期

相關博士學位論文 前1條

1 王志亮;軟基路堤沉降預測和計算[D];河海大學;2004年

相關碩士學位論文 前2條

1 蘇志業(yè);基于改進鄧肯—張模型的土工格柵加筋擋土墻數值分析研究[D];南昌航空大學;2011年

2 劉娜;土石壩三維非線性有限元分析及防滲墻應力狀態(tài)研究[D];西安理工大學;2007年

，

本文編號：1487281