城市地下結(jié)構(gòu)施工對(duì)鄰近構(gòu)筑物影響的研究
發(fā)布時(shí)間：2018-09-02 05:50
【摘要】：在日益發(fā)展的城市化進(jìn)程中，密集的高層與超高層建筑和發(fā)達(dá)的地下交通網(wǎng)絡(luò)已成為城市必不可少的重要組成部分�；庸こ坛Ｌ幱诿芗募扔薪�(構(gòu))筑物附近，基坑施工受到了更加嚴(yán)格的環(huán)境制約。預(yù)測(cè)基坑施工引起的變形及其對(duì)周邊環(huán)境的影響，對(duì)于城市中心地區(qū)深基坑的設(shè)計(jì)與施工具有重要指導(dǎo)意義，為了更好跟有效地保護(hù)鄰近建筑物的安全，在深基坑工程中，對(duì)開挖卸荷力學(xué)效應(yīng)的研究變得更加意義重大。 在眾多對(duì)基坑工程變形與穩(wěn)定研究中起到重要作用的因素中，土體抗剪強(qiáng)度和本構(gòu)模型是最為關(guān)鍵的，而它們的準(zhǔn)確性與土體應(yīng)力路徑有著密切的關(guān)系。本文結(jié)合廣州中心城區(qū)深基坑工程實(shí)踐，采用試驗(yàn)研究、理論分析、數(shù)值模擬等方法，對(duì)城市地下結(jié)構(gòu)施工對(duì)周邊環(huán)境的影響進(jìn)行了研究,取得了以下創(chuàng)新性研究成果。 1.對(duì)廣州市的地質(zhì)分區(qū)進(jìn)行調(diào)研，給出廣州市各巖土環(huán)境分區(qū)對(duì)地下工程適應(yīng)性的評(píng)價(jià)，確定了中心城區(qū)典型土體為研究對(duì)象，結(jié)合廣州市崗頂酒店基坑工程，采用SLB-1型應(yīng)力應(yīng)變控制式三軸剪切滲透試驗(yàn)儀，對(duì)基坑開挖影響范圍內(nèi)的淤泥質(zhì)土、粉質(zhì)粘土層進(jìn)行了常規(guī)三軸試驗(yàn)和考慮應(yīng)力路徑的k0固結(jié)卸荷試驗(yàn)，對(duì)土體的抗剪強(qiáng)度指標(biāo)與應(yīng)力應(yīng)變關(guān)系的差異在不同固結(jié)壓力和應(yīng)力路徑條件下進(jìn)行對(duì)比分析了。試驗(yàn)結(jié)果表明：前期固結(jié)壓力對(duì)土體強(qiáng)度的影響比較大，k0固結(jié)后土體的強(qiáng)度比等壓固結(jié)的強(qiáng)度高，在土樣同屬于壓縮剪切破壞的情況下，加載條件與卸載條件下土樣的破壞強(qiáng)度相差不大。土體孔隙水壓力的隨軸向應(yīng)變的變化規(guī)律與土體的平均固結(jié)壓力、土質(zhì)以及應(yīng)力路徑有關(guān)，對(duì)于常規(guī)三軸試驗(yàn)、k0固結(jié)加載試驗(yàn)以及側(cè)向卸載試驗(yàn)，孔隙水壓力的隨軸向應(yīng)變的變化趨勢(shì)可以用指數(shù)衰減性的函數(shù)曲線來擬合，而軸向卸載試驗(yàn)中孔隙水壓力的隨軸向應(yīng)變的變化趨勢(shì)可以用兩段二次拋物線的函數(shù)曲線來擬合，總的來說，土體的平均固結(jié)壓力越大、塑性指數(shù)越高孔隙水壓力上升得越快，臨界孔隙水壓力越大。 2.基于不同應(yīng)力路徑下土體試驗(yàn)的結(jié)果，驗(yàn)證了k0固結(jié)條件土體在不同應(yīng)力路徑下關(guān)系曲線存在很好的線性關(guān)系，說明k12K m10固結(jié)條件下卸荷狀態(tài)下的曲線能夠用雙曲線來擬合，以此為基礎(chǔ)，把土體在不同應(yīng)力路徑下非線性彈性模型的切線模量表達(dá)式推導(dǎo)出來，給出了土體卸荷非線性彈性本構(gòu)模型參數(shù)的確定方法。通過對(duì)（13）—曲線的分析，得到：初始切線模量與應(yīng)力路徑、土質(zhì)以及平均固結(jié)壓力有關(guān)，土體的平均固結(jié)壓力越大隨之塑性指數(shù)越低初始切線模量也越大；軸向卸載的初始切線模量值最大、側(cè)向卸載的初始切線模量次之、軸向加載的初始切線模量最��；軸向加載的初始切線模量與圍壓的關(guān)系可以用冪函數(shù)來表示，而側(cè)向卸載、軸向卸載的初始切線模量與圍壓成線性關(guān)系。 3.基于MIDAS/GTS有限元分析軟件，采用土體卸荷非線性彈性本構(gòu)模型，從基坑開挖施工全過程、基坑開挖的空間作用、盾構(gòu)隧道等效剛度折算系數(shù)大小、隧道所處土層彈性模量大小等來研究基坑開挖對(duì)下方盾構(gòu)隧道變形的影響，并結(jié)合崗頂酒店基坑工程實(shí)例進(jìn)行分析。分析表明，隨著基坑開挖，下方隧道豎向位移的增量比水平位移的增量要大，總體來說，深基坑開挖引起隧道的變形以豎向變形為主。盾構(gòu)隧道變形主要受其上方基坑開挖的影響，隧道上方的基坑開挖，對(duì)隧道變形的影響程度較小。 4.通過引入盾構(gòu)管片的等效縱向剛度、等效橫向剛度，來簡(jiǎn)化盾構(gòu)管片的計(jì)算模型�；贛IDAS/GTS有限元分析軟件，采用土體卸荷非線性彈性本構(gòu)模型，從鄰近隧道的空間相對(duì)位置、盾構(gòu)隧道等效剛度折算系數(shù)大小、隧道所處土層彈性模量大小等來研究隧道施工對(duì)下鄰近隧道的影響。分析表明，在盾構(gòu)隧道下方，沿著盾構(gòu)隧道方向修建隧道(0°)時(shí)，上方盾構(gòu)的變形也是沿著全長(zhǎng)范圍的，，受新建隧道的影響最大。當(dāng)盾構(gòu)隧道和新建隧道夾角45°和90°時(shí)，上方盾構(gòu)隧道管片變形分布具有明顯的對(duì)稱性，沿著盾構(gòu)隧道向兩邊延伸，新建隧道對(duì)其的影響逐漸減弱。兩隧道夾角45°~90°之間，交疊處影響效果很接近；45°時(shí)的情況下兩隧道交疊范圍較大，因此其影響范圍也相對(duì)較大，所以沿著盾構(gòu)隧道兩個(gè)方向上，盾構(gòu)管片變形減小的速率要小。 5.結(jié)合崗頂酒店基坑工程實(shí)例，引入遺傳算法對(duì)傳統(tǒng)的BP神經(jīng)網(wǎng)絡(luò)進(jìn)行改進(jìn)，通過遺傳算法搜索，確定了該樣本參數(shù)下最優(yōu)的隱含層節(jié)點(diǎn)數(shù)及最大循環(huán)次數(shù)，通過自學(xué)習(xí)與訓(xùn)練確定了最優(yōu)的神經(jīng)網(wǎng)絡(luò)權(quán)值參數(shù)，提出了深基坑開挖沉降及水平位移預(yù)測(cè)的基于遺傳BP網(wǎng)絡(luò)建模方法，實(shí)現(xiàn)了降低巖體力學(xué)參數(shù)的變異性所對(duì)模型造成的誤差，僅在一定范圍內(nèi)取值計(jì)算，其預(yù)測(cè)結(jié)果的精度得到保證，通過實(shí)例預(yù)測(cè)可以看出，四組預(yù)測(cè)值與實(shí)測(cè)值中最大的絕對(duì)水平位移誤差為0.25mm，最大的沉絕對(duì)沉降位移誤差為0.09mm；最大的相對(duì)水平位移誤差為1.7%，最大的相對(duì)沉降位移誤差為1.57%。
[Abstract]:In the process of urbanization, dense high-rise and super-high-rise buildings and developed underground transportation network have become an indispensable part of the city. Foundation pit engineering is often located near dense existing buildings. Foundation pit construction is subject to more stringent environmental constraints. The influence of surrounding environment has important guiding significance for the design and construction of deep foundation pit in urban center area. In order to better and effectively protect the safety of adjacent buildings, the study of mechanical effect of excavation unloading becomes more significant in deep foundation pit engineering.
Among the factors that play an important role in the study of deformation and stability of foundation pit engineering, the shear strength and constitutive model of soil are the most important, and their accuracy is closely related to the stress path of soil. The influence of urban underground structure construction on surrounding environment is studied and the following innovative research results are obtained.
1. By investigating the geological zoning of Guangzhou City, the adaptability of each geotechnical environment zoning to underground engineering in Guangzhou City is evaluated, and the typical soil body in the central city is selected as the research object. Combined with the foundation pit engineering of Guangzhou Gangding Hotel, the SLB-1 triaxial shear permeability tester with stress-strain control is adopted to test the influence of foundation pit excavation. Conventional triaxial tests and k_0 consolidation and unloading tests with stress paths in silty soil and silty clay layers were carried out. The differences between shear strength index and stress-strain relationship were compared and analyzed under different consolidation pressures and stress paths. The strength of soil after K 0 consolidation is higher than that of isobaric consolidation. The failure strength of soil samples under loading and unloading conditions is similar to that under compression and shear failure. The variation of pore water pressure with axial strain is related to the average consolidation pressure, soil quality and stress path of the soil. For the conventional 3. In axial test, K 0 consolidation loading test and lateral unloading test, the variation trend of pore water pressure with axial strain can be fitted by exponential decay function curve, while the variation trend of pore water pressure with axial strain in axial unloading test can be fitted by two quadratic parabola function curve. Generally speaking, soil mass The higher the average consolidation pressure, the higher the plastic index, the faster the increase of pore water pressure and the greater the critical pore water pressure.
2. Based on the results of soil tests under different stress paths, it is verified that there is a good linear relationship between the curves of soil under different stress paths under k_0 consolidation conditions. It is shown that the curves under unloading conditions under k_12K_m10 consolidation can be fitted by hyperbola. On this basis, the nonlinear elastic model of soil under different stress paths is established. The formula of tangent modulus is deduced and the method to determine the parameters of the nonlinear elastic constitutive model for unloading soils is given. Through the analysis of (13) - curve, it is found that the initial tangent modulus is related to stress path, soil quality and average consolidation pressure, and the greater the average consolidation pressure, the lower the initial tangent modulus is with the plastic index. The initial tangent modulus of axial unloading is the largest, the initial tangent modulus of lateral unloading is the second, and the initial tangent modulus of axial loading is the smallest; the relationship between the initial tangent modulus of axial loading and confining pressure can be expressed by power function, while the initial tangent modulus of axial unloading is linear with confining pressure.
3. Based on the MIDAS/GTS finite element analysis software, the influence of excavation on the deformation of shield tunnel is studied by using the nonlinear elastic constitutive model of soil unloading, including the whole process of excavation, the spatial effect of excavation, the equivalent stiffness conversion coefficient of shield tunnel and the elastic modulus of soil layer. The analysis of a hotel foundation pit project shows that the increment of the vertical displacement of the tunnel below is larger than that of the horizontal displacement with the excavation of the foundation pit. Generally speaking, the deformation of the tunnel caused by the excavation of the deep foundation pit is mainly vertical deformation. The influence of deformation is less.
4. The calculation model of shield segment is simplified by introducing the equivalent longitudinal stiffness and transverse stiffness of shield segment. Based on the MIDAS/GTS finite element analysis software, the nonlinear elastic constitutive model of unloading soil is adopted to calculate the equivalent stiffness of shield tunnel from the relative position of adjacent tunnel, the equivalent stiffness conversion coefficient of shield tunnel, and the elastic modulus of soil layer. The analysis shows that under the shield tunnel, the deformation of the upper shield is along the whole length of the tunnel when the tunnel is constructed along the direction of the shield tunnel (0 degree), and the influence of the new tunnel is the greatest. When the angle between the shield tunnel and the new tunnel is 45 degree and 90 degree, the segment of the upper shield tunnel is deformed. The distribution is obviously symmetrical, and the influence of the new tunnel is gradually weakened along the shield tunnel extending to both sides. The effect of the overlap between the two tunnels is very close when the angle of the tunnel is between 45 degrees and 90 degrees. The overlap area of the two tunnels is larger when the angle is between 45 degrees and 90 degrees, so the influence scope of the two tunnels is relatively large. The rate of deformation decreases.
5. Combining with the engineering example of the foundation pit of Gangding Hotel, genetic algorithm is introduced to improve the traditional BP neural network. The optimal number of hidden layer nodes and the maximum number of cycles under the sample parameters are determined by genetic algorithm search. The optimal neural network weight parameters are determined by self-learning and training, and the settlement of deep foundation pit excavation and the maximum number of cycles are proposed. Horizontal displacement prediction based on genetic BP network modeling method can reduce the errors caused by the variability of mechanical parameters of rock mass. The accuracy of prediction results can be guaranteed only by calculating values within a certain range. The maximum absolute settlement displacement error is 0.09 mm, the maximum relative horizontal displacement error is 1.7%, and the maximum relative settlement displacement error is 1.57%.
【學(xué)位授予單位】：長(zhǎng)安大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2013
【分類號(hào)】：TU94
[Abstract]:In the process of urbanization, dense high-rise and super-high-rise buildings and developed underground transportation network have become an indispensable part of the city. Foundation pit engineering is often located near dense existing buildings. Foundation pit construction is subject to more stringent environmental constraints. The influence of surrounding environment has important guiding significance for the design and construction of deep foundation pit in urban center area. In order to better and effectively protect the safety of adjacent buildings, the study of mechanical effect of excavation unloading becomes more significant in deep foundation pit engineering.
Among the factors that play an important role in the study of deformation and stability of foundation pit engineering, the shear strength and constitutive model of soil are the most important, and their accuracy is closely related to the stress path of soil. The influence of urban underground structure construction on surrounding environment is studied and the following innovative research results are obtained.
1. By investigating the geological zoning of Guangzhou City, the adaptability of each geotechnical environment zoning to underground engineering in Guangzhou City is evaluated, and the typical soil body in the central city is selected as the research object. Combined with the foundation pit engineering of Guangzhou Gangding Hotel, the SLB-1 triaxial shear permeability tester with stress-strain control is adopted to test the influence of foundation pit excavation. Conventional triaxial tests and k_0 consolidation and unloading tests with stress paths in silty soil and silty clay layers were carried out. The differences between shear strength index and stress-strain relationship were compared and analyzed under different consolidation pressures and stress paths. The strength of soil after K 0 consolidation is higher than that of isobaric consolidation. The failure strength of soil samples under loading and unloading conditions is similar to that under compression and shear failure. The variation of pore water pressure with axial strain is related to the average consolidation pressure, soil quality and stress path of the soil. For the conventional 3. In axial test, K 0 consolidation loading test and lateral unloading test, the variation trend of pore water pressure with axial strain can be fitted by exponential decay function curve, while the variation trend of pore water pressure with axial strain in axial unloading test can be fitted by two quadratic parabola function curve. Generally speaking, soil mass The higher the average consolidation pressure, the higher the plastic index, the faster the increase of pore water pressure and the greater the critical pore water pressure.
2. Based on the results of soil tests under different stress paths, it is verified that there is a good linear relationship between the curves of soil under different stress paths under k_0 consolidation conditions. It is shown that the curves under unloading conditions under k_12K_m10 consolidation can be fitted by hyperbola. On this basis, the nonlinear elastic model of soil under different stress paths is established. The formula of tangent modulus is deduced and the method to determine the parameters of the nonlinear elastic constitutive model for unloading soils is given. Through the analysis of (13) - curve, it is found that the initial tangent modulus is related to stress path, soil quality and average consolidation pressure, and the greater the average consolidation pressure, the lower the initial tangent modulus is with the plastic index. The initial tangent modulus of axial unloading is the largest, the initial tangent modulus of lateral unloading is the second, and the initial tangent modulus of axial loading is the smallest; the relationship between the initial tangent modulus of axial loading and confining pressure can be expressed by power function, while the initial tangent modulus of axial unloading is linear with confining pressure.
3. Based on the MIDAS/GTS finite element analysis software, the influence of excavation on the deformation of shield tunnel is studied by using the nonlinear elastic constitutive model of soil unloading, including the whole process of excavation, the spatial effect of excavation, the equivalent stiffness conversion coefficient of shield tunnel and the elastic modulus of soil layer. The analysis of a hotel foundation pit project shows that the increment of the vertical displacement of the tunnel below is larger than that of the horizontal displacement with the excavation of the foundation pit. Generally speaking, the deformation of the tunnel caused by the excavation of the deep foundation pit is mainly vertical deformation. The influence of deformation is less.
4. The calculation model of shield segment is simplified by introducing the equivalent longitudinal stiffness and transverse stiffness of shield segment. Based on the MIDAS/GTS finite element analysis software, the nonlinear elastic constitutive model of unloading soil is adopted to calculate the equivalent stiffness of shield tunnel from the relative position of adjacent tunnel, the equivalent stiffness conversion coefficient of shield tunnel, and the elastic modulus of soil layer. The analysis shows that under the shield tunnel, the deformation of the upper shield is along the whole length of the tunnel when the tunnel is constructed along the direction of the shield tunnel (0 degree), and the influence of the new tunnel is the greatest. When the angle between the shield tunnel and the new tunnel is 45 degree and 90 degree, the segment of the upper shield tunnel is deformed. The distribution is obviously symmetrical, and the influence of the new tunnel is gradually weakened along the shield tunnel extending to both sides. The effect of the overlap between the two tunnels is very close when the angle of the tunnel is between 45 degrees and 90 degrees. The overlap area of the two tunnels is larger when the angle is between 45 degrees and 90 degrees, so the influence scope of the two tunnels is relatively large. The rate of deformation decreases.
5. Combining with the engineering example of the foundation pit of Gangding Hotel, genetic algorithm is introduced to improve the traditional BP neural network. The optimal number of hidden layer nodes and the maximum number of cycles under the sample parameters are determined by genetic algorithm search. The optimal neural network weight parameters are determined by self-learning and training, and the settlement of deep foundation pit excavation and the maximum number of cycles are proposed. Horizontal displacement prediction based on genetic BP network modeling method can reduce the errors caused by the variability of mechanical parameters of rock mass. The accuracy of prediction results can be guaranteed only by calculating values within a certain range. The maximum absolute settlement displacement error is 0.09 mm, the maximum relative horizontal displacement error is 1.7%, and the maximum relative settlement displacement error is 1.57%.
【學(xué)位授予單位】：長(zhǎng)安大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2013
【分類號(hào)】：TU94
【參考文獻(xiàn)】
相關(guān)期刊論文 前10條
1 徐湘濤;汪家林;趙昌貴;;深基坑開挖過程中的穩(wěn)定性監(jiān)測(cè)分析[J];四川建筑科學(xué)研究;2009年04期
2 潘濤;BP神經(jīng)網(wǎng)絡(luò)模型中活化函數(shù)對(duì)網(wǎng)絡(luò)性能影響的研究[J];安徽師大學(xué)報(bào)(自然科學(xué)版);1998年03期
3 高瑋,鄭穎人;巖土工程位移預(yù)測(cè)神經(jīng)網(wǎng)絡(luò)建模的幾個(gè)問題[J];地下空間;2001年S1期
4 徐中華;;大開口式逆作法深基坑實(shí)測(cè)變形分析[J];地下空間與工程學(xué)報(bào);2009年04期
5 方燾;梁寧慧;耿大新;;SMW工法圍護(hù)軟粘土深基坑開挖蠕變特性分析[J];地下空間與工程學(xué)報(bào);2009年04期
6 陳洪勝;陳寶;賀
本文編號(hào)：2218452
本文鏈接：http://sikaile.net/kejilunwen/sgjslw/2218452.html
最近更新
教材專著
