發(fā)布時間：2018-04-28 23:11

  本文選題：巖土工程 + 公路橋梁��； 參考：《長安大學》2015年碩士論文

【摘要】：由于巖溶區(qū)地質條件復雜,使得公路橋梁樁基施工對鄰近既有鐵路路基穩(wěn)定性影響較大,因此,有必要對巖溶區(qū)橋梁樁基施工對鄰近既有鐵路路基的影響展開研究。本文以肇花高速公路建設項目為依托工程,通過對京廣鐵路附近巖溶發(fā)育區(qū)域橋梁樁基施工進行現(xiàn)場監(jiān)測,并結合有限元數(shù)值模擬,提出了相應的巖溶區(qū)橋梁樁基設計與施工安全控制技術。主要成果如下:1.通過現(xiàn)場實測資料得出:(1)鄰近肇花高速公路樁基施工區(qū)域的京廣鐵路路基未發(fā)生顯著的深層水平位移和地表沉降變形,可判定樁基施工期間,京廣鐵路路基穩(wěn)定,樁基施工并未顯著威脅其穩(wěn)定性;(2)地下水位未發(fā)生顯著變化,不足以產(chǎn)生顯著的水力梯度威脅巖溶地區(qū)巖土體的穩(wěn)定性。2.通過有限元數(shù)值模擬計算得出:(1)在樁孔與路基距離一定情況下,隨著泥漿相對密度的增大,路基最大水平位移和沉降均呈減小的趨勢,兩者均在超過相對密度1.35后趨于穩(wěn)定;(2)隨著溶洞尺寸的增加,路基最大水平位移和沉降成明顯增加趨勢,且溶洞尺寸越大,增加幅度越快;(3)在溶洞尺寸及樁孔和路基距離一定的情況下,溶洞離地面的距離越近對路基的影響越大,溶洞處于樁孔上部位置時對路基影響要遠遠大于在樁孔底部的位置;(4)樁孔與路基的距離越近,影響相對越大,當大于6~8m(約3~4倍樁徑D)時,樁基施工對鄰近路基的影響很小,處于穩(wěn)定階段。3.數(shù)值模擬計算結果與現(xiàn)場監(jiān)測結果反映的規(guī)律相一致,驗證了數(shù)值模擬計算的可靠性,可為相似巖溶區(qū)橋梁樁基施工建設工程提供一定的參考性,避免憑經(jīng)驗方法估計對鄰近構筑物的影響。4.為減小樁基施工對鄰近既有鐵路路基的影響,提出了相應的巖溶區(qū)橋梁樁基設計與施工安全控制技術,填補了現(xiàn)行巖溶區(qū)橋梁樁基設計與施工存在的難點。
[Abstract]:Because of the complex geological conditions in karst area, the pile foundation construction of highway bridge has a great influence on the stability of adjacent existing railway subgrade. Therefore, it is necessary to study the influence of the bridge pile foundation construction on the adjacent existing railway subgrade. The site monitoring of the bridge pile foundation in the breeding area is carried out, and the design and construction safety control techniques of bridge pile foundation in karst area are put forward in combination with the finite element numerical simulation. The main achievements are as follows: 1. (1) there is no significant deep level of the Jing Guang Railway Subgrade in the pile foundation construction area adjacent to Zhaohua expressway. The deformation of displacement and ground subsidence can determine the stability of the subgrade of Beijing and Guangzhou railway during the construction of pile foundation, and the pile foundation construction does not threaten its stability significantly. (2) there is no significant change in the groundwater level, which is not enough to produce significant hydraulic gradient to threaten the stability of rock and soil in karst area. (1) the pile hole and road are obtained by the finite element numerical simulation. When the base distance is certain, the maximum horizontal displacement and settlement of the subgrade decrease with the increase of the relative density of the mud. Both of them tend to be stable after the relative density of 1.35. (2) the maximum horizontal displacement and settlement of the subgrade increase with the increase of the cave size, and the larger the cave size, the faster the increase; (3) When the size of the karst cave and the distance between the pile hole and the subgrade is certain, the closer the distance from the cave is to the ground, the greater the influence on the subgrade, and the effect of the cave in the upper position of the pile is far greater than the position at the bottom of the pile hole. (4) the closer the distance between the pile hole and the subgrade, the greater the influence of the phase, and the pile foundation construction when it is greater than 6~8m (about 3~4 times the pile diameter D). The effect on the adjacent subgrade is very small. The numerical simulation results of.3. in the stable stage are in accordance with the law of the monitoring results, and the reliability of the numerical simulation is verified. It can provide some reference for the construction of bridge pile foundation in similar karst area, and avoid the influence of.4. on the adjacent structures by the empirical method. In order to reduce the influence of pile foundation construction on adjacent existing railway subgrade, the corresponding design and construction safety control techniques of bridge pile foundation in karst area have been put forward, which fill the difficulties in the design and construction of bridge pile foundation in the current karst area.

【學位授予單位】：長安大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：U213.1;U445.551

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