| Summary: | 碩士 === 中原大學 === 土木工程研究所 === 107 === This study focused on the evaluation of the differences of axial compression interpretation criteria and pile tip capacity of post grouting drilled shafts. Axial compression of rectangular and circular drilled shafts was collected and utilized for the study. For more accurate analyses, the drilled shaft data was divided into undrained and drained soil according to the soils along shaft length. Meanwhile, various interpretation criteria, including high, medium, and low boundary criteria were used for analysis. In the part of pile tip capacity, the drilled shaft data was divided into cohesive soil, sandy soil, gravel, and rock according to the shaft tip soil property, then evaluated the capacity and concluded the difference between the theoretical and the actual capacity (L2 method) with post grouting.
Results showed that for the interpretation criteria of rectangular drilled shafts, the average settlement of the L2 criteria of both undrained and drained soil with pile tip jet cleaning and grouting method is larger than the standard pile. Also, for the interpretation criteria of circular drilled shafts, the average settlement of undrained and drained soil with tube-a-manchette method, flat jack method and pile tip jet cleaning and grouting method are larger than the standard. Therefore, the tip capacity ratio of L2 criteria of both the rectangular and circular drilled shafts resulted into larger values than the normal ones.
For the tip capacity of rectangular drilled shafts, the actual tip capacity in cohesive soil and rock with pile tip jet cleaning and grouting method is larger than the theoretical capacity, while the actual tip capacity in sandy soil and gravel resulted in a less value than the theoretical capacity. For the tip capacity of circular drilled shafts, the actual tip capacity in cohesive soil and rock with tube-a-manchette method is similar to the theoretical, while the tip capacity in sandy soil and gravel resulted in a less value than the theoretical; additionally, the actual tip capacity in gravel with flat jack method is less than the theoretical; and lastly, the actual tip capacity in cohesive soil and rock with pile tip jet cleaning and grouting method gained a larger than the theoretical capacity value, while the actual tip capacity in gravel is less than the theoretical. Moreover, this study also establishes relationship between the post-grouting pile tip bearing stress and N value of standard penetration test (SPT-N) or uniaxial compressive strength of rock (qu) and compares with the standard drilled shafts.
Based on these analyses, this study concluded the axial compression behavior of drilled shafts with post grouting, to be used as a recommendation for engineering design.
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