本文選題：基坑　切入點：等效m值　出處：《昆明理工大學》2017年碩士論文　論文類型：學位論文

【摘要】：在基坑工程中,由于平面豎向彈性地基梁法計算模式明確、計算過程簡單,在實際工程中得到廣泛的應用。其中,土的水平反力系數(shù)的比例系數(shù)—m值的取值尤為關鍵,不僅影響到支護結(jié)構(gòu)的變形和內(nèi)力,甚至決定了支護結(jié)構(gòu)的設計和圍護方案的選擇。限于試驗條件的限制,目前的工程勘察報告中尚不能正確提供各類土層的水平基床系數(shù),現(xiàn)有的規(guī)程和指南雖給出了 m值的參考值,但選擇的范圍較大,取值存在不確定性和隨意性。準確、合理的m值不僅能夠真實反映結(jié)構(gòu)實際的工作狀態(tài),也可為類似工程設計提供參考,具有重要的工程意義。本文依據(jù)實測水平位移監(jiān)測數(shù)據(jù),采用了基于樣條函數(shù)反分析和基于彈性支點法的正分析相結(jié)合的方法對基坑土層等效m值進行反演,具體開展了以下幾個方面的研究工作:(1)本文在假定和簡化的基礎上,對平面桿系結(jié)構(gòu)彈性支點法中土的水平反力系數(shù)進行了分析,得到了與其有關的系數(shù)△1、△2且提出了一個綜合考慮土體重度γ,基坑開挖深度h,側(cè)壓力系數(shù)k0和抗剪強度指標的等效m值計算公式。(2)采用光順樣條函數(shù),按一定的光順準則和逼近準則對水平位移監(jiān)測數(shù)據(jù)進行平滑處理;然后,利用B樣條函數(shù)對平滑后的數(shù)據(jù)進行插值,得到基坑支護樁的位移樣條函數(shù),對位移樣條函數(shù)求導,反算出基坑支護樁的內(nèi)力值。(3)按平面桿系結(jié)構(gòu)彈性支點法,建立基坑力學計算模型,采用矩陣位移法正算基坑支護樁的變形和內(nèi)力值。(4)將△1、△2作為待反演參數(shù),在其取值范圍內(nèi)枚舉出大量的參數(shù)組合,逐一代入正算模型中計算,得到每種組合所對應的支護樁的變形和內(nèi)力值。利用實際變形和反算內(nèi)力值篩選出其允許容差范圍內(nèi)的正算值所對應的參數(shù)樣本,以確定系數(shù)△1、△2,從而間接反演得到基坑土層等效m值。(5)選取某一實際工程,依照上述反分析方法反演確定系數(shù)△1、△2,并由此計算出下一工況的基坑土層等效m值,將其代入基坑力學計算模型,正算出基坑支護樁后續(xù)工況的變形和內(nèi)力值,并與位移實際值和內(nèi)力反算值作比較,驗證反分析結(jié)果的可靠性與反分析算法的可行性。
[Abstract]:In foundation pit engineering, the calculation model of beam method for plane vertical elastic foundation is clear, and the calculation process is simple, so it is widely used in practical engineering, among which, the ratio coefficient -m of horizontal reaction coefficient of soil is particularly important. It not only affects the deformation and internal force of the supporting structure, but also determines the design of the supporting structure and the selection of the enclosure scheme. Limited to the limit of the test conditions, the horizontal bed coefficient of all kinds of soil can not be correctly provided in the present engineering survey report. Although the existing regulations and guidelines give the reference value of m value, but the selection range is large, the value is uncertain and arbitrary, the accurate and reasonable m value can not only truly reflect the actual working state of the structure. It can also be used as a reference for similar engineering design and has important engineering significance. In this paper, the equivalent m value of foundation pit soil layer is inversed by the combination of spline function back analysis and forward analysis based on elastic fulcrum method. The following research work is carried out in detail: 1) on the basis of supposition and simplification, this paper is based on the assumption and simplification. The horizontal reaction coefficient of soil in the elastic fulcrum method of plane bar structure is analyzed. The relative coefficient of 1, 2 is obtained and a formula of equivalent m value of considering soil weight 緯, excavation depth of foundation pit, lateral pressure coefficient k _ 0 and shear strength index is proposed, which adopts fairing spline function. The horizontal displacement monitoring data are smoothed according to certain fairing criterion and approximation criterion, and then the displacement spline function of foundation pit supporting pile is obtained by interpolating the smooth data with B-spline function, and the displacement spline function is derived. The mechanical calculation model of foundation pit is established according to the elastic fulcrum method of plane bar structure, and the deformation and internal force of supporting pile of foundation pit are calculated by matrix displacement method. A large number of parameter combinations are enumerated in the range of their values, and are substituted one by one into the positive calculation model. The deformation and internal force of the supporting pile corresponding to each combination are obtained. By using the actual deformation and the inverse internal force, the parameter samples corresponding to the positive values within the allowable tolerance range are selected. In this paper, the equivalent m value of foundation pit soil layer is obtained by indirect inversion, and then a practical project is selected, and the coefficient 1, 2 is obtained according to the above inverse analysis method, and the equivalent m value of foundation pit soil layer under the next working condition is calculated. The deformation and internal force of the foundation pit supporting pile are calculated by the mechanical calculation model of foundation pit, and compared with the actual displacement value and the back calculation value of the internal force, the reliability of the back analysis result and the feasibility of the back analysis algorithm are verified.
【學位授予單位】：昆明理工大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TU753

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