岩溶区公路桥梁桩基施工对邻近既有铁路路基稳定性影响分析及安全控制技术

发布时间：2018-04-28 23:11

本文选题：岩土工程 + 公路桥梁　；参考：《长安大学》2015年硕士论文

【摘要】：由于岩溶区地质条件复杂,使得公路桥梁桩基施工对邻近既有铁路路基稳定性影响较大,因此,有必要对岩溶区桥梁桩基施工对邻近既有铁路路基的影响展开研究。本文以肇花高速公路建设项目为依托工程,通过对京广铁路附近岩溶发育区域桥梁桩基施工进行现场监测,并结合有限元数值模拟,提出了相应的岩溶区桥梁桩基设计与施工安全控制技术。主要成果如下:1.通过现场实测资料得出:(1)邻近肇花高速公路桩基施工区域的京广铁路路基未发生显著的深层水平位移和地表沉降变形,可判定桩基施工期间,京广铁路路基稳定,桩基施工并未显著威胁其稳定性;(2)地下水位未发生显著变化,不足以产生显著的水力梯度威胁岩溶地区岩土体的稳定性。2.通过有限元数值模拟计算得出:(1)在桩孔与路基距离一定情况下,随着泥浆相对密度的增大,路基最大水平位移和沉降均呈减小的趋势,两者均在超过相对密度1.35后趋于稳定;(2)随着溶洞尺寸的增加,路基最大水平位移和沉降成明显增加趋势,且溶洞尺寸越大,增加幅度越快;(3)在溶洞尺寸及桩孔和路基距离一定的情况下,溶洞离地面的距离越近对路基的影响越大,溶洞处于桩孔上部位置时对路基影响要远远大于在桩孔底部的位置;(4)桩孔与路基的距离越近,影响相对越大,当大于6~8m(约3~4倍桩径D)时,桩基施工对邻近路基的影响很小,处于稳定阶段。3.数值模拟计算结果与现场监测结果反映的规律相一致,验证了数值模拟计算的可靠性,可为相似岩溶区桥梁桩基施工建设工程提供一定的参考性,避免凭经验方法估计对邻近构筑物的影响。4.为减小桩基施工对邻近既有铁路路基的影响,提出了相应的岩溶区桥梁桩基设计与施工安全控制技术,填补了现行岩溶区桥梁桩基设计与施工存在的难点。
[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.

【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U213.1;U445.551

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