龚晓南1?覮,邵佳函1,解才1,舒佳明2.桩端扩大头尺寸对承载性能影响模型试验[J].湖南大学学报:自然科学版,2018,45(11):102~109
桩端扩大头尺寸对承载性能影响模型试验
Model Test on Influence of Enlarged Head Size on Bearing Capacity of Pile End
  
DOI:
中文关键词:  桩端扩大头  尺寸  模型试验  承载性能  端阻力  桩端沉降计算
英文关键词:expanded foot of pile tip  size  model test  bearing capacity  tip resistance  pile tip settlement calculation
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作者单位
龚晓南1?覮,邵佳函1,解才1,舒佳明2 (1.浙江大学 建筑工程学院浙江 杭州 3100582.中淳高科桩业股份有限公司浙江 宁波 315000) 
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中文摘要:
      为了研究注浆加固体体积即扩大头尺寸对桩端承载性能的作用效果,本试验通过往PVC管内注浆,改变注浆量和PVC管尺寸来控制扩大头尺寸,然后以此开展室内单桩静载模型试验,最后采用了传统桩端沉降公式计算得出桩端阻力-位移曲线并与实测曲线对比.结果表明:桩端灌注水泥土形成扩大头的桩,相比未注浆的桩,其承载力显著提高,在相同的荷载下,其沉降显著变小;随着扩大头直径的增加,承载力持续增长,但每单位直径增加所提高的承载力先增后减,在工作荷载下对减少位移的效果呈递减趋势;端阻分担比在位移5 cm后趋于稳定,其中桩端水泥土扩大头承担较高的端阻比例,且其比例随扩大头直径的增大而增大,由于水泥土受力较大,实际工程中应该注意桩端水泥土的强度;传统桩端沉降公式计算的桩端阻力-位移曲线与实测曲线吻合良好.
英文摘要:
      To examine the effect of volume of grouting reinforcement body, namely the size of the expanded foot, on the bearing capacity of pile tip, indoor single-pile static-load model tests were conducted through injecting grout into PVC pipe and changing grout amount and PVC pipe size to control the size of the expanded foot. Finally, the pile tip resistance-displacement curves were calculated by the traditional pile tip settlement formula and compared with the measured curves. The results show that when comparing with the pile without grout injection, the piles that form expanded foot after being injected cement soil show the significantly improved bearing capacity, and dramatically reduced settlement under the same load; As the diameter of expanded foot increases, the bearing capacity continues to rise; However, the bearing capacity improved with the increase of per unit diameter at first and then decreased, and its effect on reducing displacement under working load shows a decline trend; The sharing ratio of tip resistance tends to be stable after a displacement of 5 cm. The cement soil expanded foot on pile tip has high ratio of tip resistance and the ratio rises as expanded foot diameter increases. In practical engineering, more importance should be attached to the strength of cement soil on pile tip for the high stress of cement soil, and the pile tip resistance-displacement curves calculated by using traditional pile tip settlement formula fit the measured curves well.
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