考虑地基土的长期压密效应在基础加固中的应用
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摘要
某6层工业厂房改造为酒店并增加3层,基础加固重点是对原沉管灌注桩桩端下部软弱土层的沉降控制。对补勘报告土层参数进行甄别分析,考虑受长期压密作用下的土体参数提高,采用短桩加固方案,发挥被固结压密粉砂层的硬壳层效应进行二次应力扩散。利用承台加固的尺寸效应考虑桩土共同工作,并在施工阶段进行施工工况计算、施工监测及沉降观测,实行延迟封桩、分批封桩的主动控制措施。通过试压桩、单桩静载荷试验、压桩施工过程试验,验证了已有厂房下的地基土具有明显的长期压密效应。加层后的沉降观测结果表明,桩端下部软弱土层的沉降增量较小。
A 6-story industrial factory building was transformed into a hotel and added 3 stories. Foundation reinforcement focused on the settlement control of the soft soil at the bottom of the original sinking pipe cast-in-place pile. The parameters of the soil layer in the supplementary survey report were screened and analyzed. Considering the improvement of the parameters of the soil under long-term compaction, the scheme of short pile reinforcement was adopted to exert the hard shell effect of the consolidated compacted silty sand layer for secondary stress diffusion. The size effect of cap reinforcement was used to consider the joint work of pile and soil, and the calculation of construction conditions, construction monitoring and settlement observation were carried out during the construction stage. The active control measures of delayed sealing and batch sealing were implemented. The long-term compaction effect of the foundation soil under the existing factory building was verified by the test pile, single pile static load test and pile-pressing construction process test. The settlement observation results after adding stories show that the settlement increment of soft soil layer at the bottom of pile tip is small.
A 6-story industrial factory building was transformed into a hotel and added 3 stories. Foundation reinforcement focused on the settlement control of the soft soil at the bottom of the original sinking pipe cast-in-place pile. The parameters of the soil layer in the supplementary survey report were screened and analyzed. Considering the improvement of the parameters of the soil under long-term compaction, the scheme of short pile reinforcement was adopted to exert the hard shell effect of the consolidated compacted silty sand layer for secondary stress diffusion. The size effect of cap reinforcement was used to consider the joint work of pile and soil, and the calculation of construction conditions, construction monitoring and settlement observation were carried out during the construction stage. The active control measures of delayed sealing and batch sealing were implemented. The long-term compaction effect of the foundation soil under the existing factory building was verified by the test pile, single pile static load test and pile-pressing construction process test. The settlement observation results after adding stories show that the settlement increment of soft soil layer at the bottom of pile tip is small.
引文
[1] 既有建筑地基基础加固技术规范:JGJ 123—2012[S].北京:中国建筑工业出版社,2013.
[2] 建筑抗震鉴定标准:GB 50023—2009[S].北京:中国建筑工业出版社,2009.
[3] 建筑桩基技术规范:JGJ 94—2008[S].北京:中国建筑工业出版社,2008.
[4] 逆作复合桩基技术规程:JGJ/T 186—2009[S].北京:中国建筑工业出版社,2010.
[2] 建筑抗震鉴定标准:GB 50023—2009[S].北京:中国建筑工业出版社,2009.
[3] 建筑桩基技术规范:JGJ 94—2008[S].北京:中国建筑工业出版社,2008.
[4] 逆作复合桩基技术规程:JGJ/T 186—2009[S].北京:中国建筑工业出版社,2010.