Elucidation of improvement mechanism and evaluation of improvement effect on ground improved by compaction grouting

压实灌浆改良地基改良机理阐明及改良效果评价

• 批准号: 12450193
• 负责人: MATSUI Tamotsu
• 金额: $ 7.23万
• 依托单位: Osaka University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2001
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-12450193/
• 关键词: liquefaction countermeasure; improvement mechanism; evaluation of improvement effect; calibration chamber; field test; compaction grouting; laboratory test; ground improvement; 高密度化; セメントグラウト; 模型実験; 現場計測

In this study, the performance of compaction grouting has been investigated through laboratory and field experimental works. For the laboratory experimental work, large-scale calibration chamber was developed. In this chamber, sandy samples (1.40 m in diameter and 1.45 m high) are prepared, consolidated and injected (using grout mortar) under conditions highly simulating the actual field conditions As the results, it was confirmed its accurate basic performance. As for the field tests, analytical study was involved based on the results of three field tests conducted in Nagoya, in Osaka and under the old taxiway of Tokyo International Airport.The main findings of this study are as follows : (1) The performance in terms of ground surface upheave is dependent on the injection depth. (2) The critical depth that characterizes the shallow and deep injections is dependent on the compaction grout pile diameter. (3) The relatively shallow injections are governed by the condition of conical shea … More ring failure of the soils overlying the masses being injected. At conical shearing failure, the attained injection pressure and grout volume are dependent on the overburden pressure and shear strength characteristics. (4) The treatment effectiveness of relatively shallow injections may be improved by terminating the injection process at just before the onset of ground surface upheave. (5) In planning the grouting works for the applications for lifting of settled structures and foundations, the required lifts can be provided only by the injections shallower than the critical depth. (6) For the applications such as in liquefaction prevention works, smaller-diameter piles may be injected while going shallower. (7) For relatively deep injections, the vertical overburden pressure has no appreciable effect on the performance. However, the performance is highly influenced by the local soil compressibility. If deformation by relative displacement of the soil particles is the dominant mechanism, the attained injection pressure will be highly correlated to the local fines content. If deformation by particle crushing is the dominant mechanism, the resulting crushing depends on mainly injection pressure. (8) The maximum pressure from injecting a given grout volume correlates well with the tip resistance of CPT test. This correlation qualifies the maximum injection pressure as reliable criteria for evaluating the performance of compaction grouting operations. (9) In the loose sand, the improved area is limited around the grouted area. However, the wide area is uniformly improved in the dense sand. Less

通过室内和现场试验，对压密注浆的性能进行了研究。针对实验室实验工作，研制了大型标定室。在该试验室内，在高度模拟现场实际条件的条件下，对直径1.40 m、高1.45 m的砂质试样进行了制备、固结和注入（使用灌浆砂浆），验证了其准确的基本性能。关于实地试验，根据在名古屋、大阪和东京国际机场旧滑行道下进行的三次实地试验的结果进行了分析研究。主要研究结果如下：(1)地表隆起性能与注入深度有关。(2)浅注入和深注入的临界深度取决于压实灌浆桩直径。(3)相对较浅的注入受锥状shea条件的支配，注入体上覆土体的环破坏较多。在锥形剪切破坏下，获得的注入压力和浆液体积取决于覆盖层压力和抗剪强度特征。(4)在地表隆起发生前终止注入，可提高较浅注入的处理效果。(5)在规划沉降构筑物和基础吊装应用的注浆工程时，只能通过低于临界深度的注浆来提供所需的吊装。(6)在防液化工程等应用中，可以在较浅的位置注入直径较小的桩。(7)对于较深的注入，垂向覆盖层压力对性能影响不明显。但其性能受局部土体压缩性的影响较大。如果土壤颗粒的相对位移是主要的变形机制，则获得的注入压力将与局部细粒含量高度相关。如果颗粒破碎的变形是主要的机制，那么最终的破碎主要取决于注射压力。(8)一定体积灌浆的最大注入压力与CPT试验的尖端阻力具有良好的相关性。这种相关性使最大注入压力成为评价压密注浆作业性能的可靠标准。(9)在松散砂土中，改良区仅限于注浆区周围。然而，在密集的沙子中，宽面积均匀改善。少