黄土地区公路桥梁后压浆灌注桩承载力试验研究

发布时间：2018-01-12 13:23

本文关键词：黄土地区公路桥梁后压浆灌注桩承载力试验研究　出处：《长安大学》2016年硕士论文　论文类型：学位论文

【摘要】：灌注桩后压浆是指在灌注桩成桩后的一定时间内,通过在桩身内预设压浆导管以及与之相连的桩端、桩侧压浆阀并注入水泥浆,使桩端、桩侧土体(包括泥皮和沉渣)得到加固,从而提高单桩承载力,降低桩基沉降。该项技术在建筑、煤炭、水利等行业已得到广泛的应用,并取得了良好的效果,但在公路桥梁桩基中应用较少,相关的试验研究缺乏。本文以西安咸阳国际机场专用高速公路渭河特大桥为依托,针对公路桥梁后压浆灌注桩承载力开展试验研究,主要研究工作如下:(1)对试验区进行详细的地质勘探,在充分利用工程桩的基础上,制定了详细的现场试验方案,共计9根试验桩,分为三组。其中第一组桩径1.30m,桩长25m;第二组桩径1.30m,桩长36m;第三组桩径1.30m,桩长25m,采用后压浆技术。(2)试桩对比试验结果表明:后压浆试桩的回弹率在76.7%~86.2%之间,未压浆试桩的回弹率为16.3%~20.9%;同级荷载时,采用后压浆工艺的桩基沉降量较常规灌注桩沉降量减少30%~80%,且后压浆灌注桩的沉降曲线较缓和;采用联合压浆工艺的后压浆桩较常规灌注桩单桩极限承载力提高8000KN以上,增幅达50%。说明后压浆技术能显著改善基桩的承载变形特性并提高竖向承载力。(3)桩身轴力分析时,桩长25米的后压浆桩基和非后压浆桩基实测桩身轴力与数值分析基本吻合。桩侧摩阻力分析时,数值模拟得到的最大摩阻力位置普遍较实测结果偏低,其中后压浆桩基尤其显著。25米非后压浆桩基实测最大侧摩阻力位置为10~15米,最大侧摩阻力为130KPa;25米后压浆桩基实测最大侧摩阻力位置17~22米,最大侧摩阻力为180 KPa。(4)运营期沉降量监控结果表明:依托工程各桥墩桩基均小于3mm,未发生显著沉降,从沉降量的总趋势上可看出后压浆桩基运营期沉降量略小于常规钻孔灌注桩基。
[Abstract]:The post-grouting of cast-in-place pile means that in a certain period of time after the construction of the cast-in-place pile, the grouting pipe is preset in the pile body and the pile end is connected with it, and the side grouting valve of the pile is injected into the cement slurry to make the pile end. The pile side soil (including mud skin and sediment) has been strengthened so as to improve the bearing capacity of single pile and reduce the settlement of pile foundation. This technology has been widely used in construction coal water conservancy and other industries and achieved good results. However, there are few applications in the pile foundation of highway bridge, and the related experimental research is lacking. This paper relies on the Weihe River Bridge of Xi'an Xianyang International Airport Special Expressway. The main research work is as follows: 1) the detailed geological exploration of the test area is carried out, on the basis of making full use of the engineering pile. A detailed field test scheme was established, nine test piles were divided into three groups, among which the first group was 1.30m in diameter and 25m in length. The second group was 1.30m in diameter and 36m in length; The third group of piles is 1.30m in diameter and 25m in length. The results of comparative tests show that the rebound rate of post-grouting test pile is between 76.762% and 86.2%. The rebound rate of the unpressed pile is 16.3and 20.9; Under the same load, the settlement of pile foundation using post-grouting technology is 30% less than that of conventional cast-in-place pile, and the settlement curve of post-grouting cast-in-place pile is relaxed. The ultimate bearing capacity of post-grouting pile with combined grouting process is more than 8,000 KN higher than that of conventional cast-in-place pile. It shows that the post-grouting technology can improve the bearing deformation characteristics of the pile and increase the vertical bearing capacity. 3) when analyzing the axial force of the pile body. The axial force of post-grouting pile foundation and non-post-grouting pile foundation is basically consistent with the numerical analysis, and the maximum friction position obtained by numerical simulation is generally lower than that of the measured results when the pile side friction is analyzed. The maximum frictional resistance of post grouting pile foundation is 1015m and the maximum lateral friction resistance is 130KPa. The maximum lateral friction position of 25 meters post-grouting pile foundation is 1722 meters. The maximum side friction is 180 KPA. 4) the result of monitoring the settlement in operation period shows that the pile foundation of each pier is less than 3 mm and there is no significant settlement. From the general trend of settlement, it can be seen that the settlement of post-grouting pile foundation is slightly smaller than that of conventional bored pile foundation.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U443.15

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