【摘要】：隨著河道工程、引水工程、地鐵工程等加速發(fā)展,長條形基坑、狹窄基坑不斷出現(xiàn)。在這類基坑工程中,基坑的寬深比往往較小,基坑兩側(cè)圍護結(jié)構(gòu)之間距離較近,極限狀態(tài)時被動滑裂土楔體形狀可能由經(jīng)典庫侖理論中的三角形變?yōu)樘菪?此時應(yīng)考慮土體寬度和相鄰擋墻的影響。對這類問題目前一般仍然采用經(jīng)典的庫侖或朗肯理論計算被動土壓力,對于被動區(qū)土體仍沿用半無限體的假定,顯然對于狹窄基坑的情形并不適合。工程實踐中發(fā)現(xiàn),基坑的寬度越小,穩(wěn)定性越好。目前的規(guī)范推薦的抗傾覆穩(wěn)定安全系數(shù)計算公式不能反映基坑寬度的影響,造成狹窄基坑圍護結(jié)構(gòu)插入深度與寬基坑相同,基于彈性抗力法的內(nèi)力變形計算方法也不能考慮狹窄基坑的空間效應(yīng),造成了狹窄基坑設(shè)計的較大浪費。 本論文在總結(jié)國內(nèi)外有關(guān)研究成果的基礎(chǔ)之上,結(jié)合錢塘江引水工程實例,采用有限元分析方法,利用PLAXIS巖土分析軟件對狹窄基坑進行全斷面模擬,本文主要完成以下幾個方面的工作： 1.分析介紹了基坑變形的特征、類型及控制機理。 2.考慮土體與支護結(jié)構(gòu)的相互作用,建立土體與支護結(jié)構(gòu)的全斷面有限元模型,利用PLAXIS巖土分析計算軟件對基坑的分步開挖進行二維數(shù)值模擬。 3.分析了狹窄基坑與常規(guī)寬大基坑在基坑變形、支護結(jié)構(gòu)內(nèi)力、土壓力、基坑整體抗滑穩(wěn)定性等方面的差別。 4.將數(shù)值模擬結(jié)果與監(jiān)測數(shù)據(jù)進行對比分析,驗證分析模型及參數(shù)選取的可靠性和合理性。
[Abstract]:With the rapid development of river engineering, water diversion engineering and subway engineering, long and narrow foundation pits are emerging. In this kind of foundation pit engineering, the ratio of width to depth of foundation pit is usually smaller, the distance between the two sides of the foundation pit is close, and the shape of the passive sliding soil wedge may change from the triangle in the classical Coulomb theory to the trapezoid shape in the limit state. The influence of soil width and adjacent retaining wall should be considered. At present, the classical Coulomb or Rankine theory is still used to calculate the passive earth pressure. The assumption that the soil mass in the passive zone is still semi-infinite is obviously not suitable for the case of narrow foundation pit. It is found in engineering practice that the smaller the width of foundation pit, the better the stability. The formula for calculating the safety factor of anti-overturning stability, which is recommended in the current code, cannot reflect the influence of the width of the foundation pit, resulting in the insertion depth of the retaining structure of the narrow foundation pit being the same as that of the wide foundation pit. The calculation method of internal force deformation based on elastic resistance method can not take into account the space effect of narrow foundation pit, which results in a great waste in the design of narrow foundation pit. On the basis of summing up the domestic and foreign research results, combined with the Qiantang River diversion project, the finite element analysis method and PLAXIS geotechnical analysis software are used to simulate the whole section of narrow foundation pit. This paper mainly completes the following aspects of the work: 1. The characteristics, types and control mechanism of foundation pit deformation are analyzed and introduced. 2. Considering the interaction between soil and supporting structure, a full-section finite element model of soil and supporting structure is established, and the two-dimension numerical simulation of excavation is carried out by using PLAXIS geotechnical analysis and calculation software. The differences between narrow foundation pit and conventional large foundation pit in deformation of foundation pit, internal force of supporting structure, earth pressure and overall stability of foundation pit are analyzed. 4. The numerical simulation results are compared with the monitoring data to verify the reliability and rationality of the model and parameter selection.
【學(xué)位授予單位】：浙江大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TV223;TV67

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本文編號：2294152