台北捷運噴射灌漿改良土之力學性質

Mechanical Properties of Jet-Grouted Soilcrete from Taipei MRT Construction

方永壽(Yung-Show Fang) ； 鍾雅君(Ya-Chin Chung) ； 陳滄江(Tsang-Jiang Chen)

《地工技術》 78期 (2000/04) Pp. 75-85

https://doi.org/10.30140/SG.200004.0005

摘要

本文介紹台北捷運南港線噴射灌漿施工所形成改良土之力學性質。為防止捷運隧道開挖造成鄰近地盤沉陷過大，可能損及鄰近建築物，施工單位在潛盾機通過前，先行改良隧道周圍之地盤。灌漿20天後，研究人員至工地鑽取圓柱形改良土試體，並進行各項試驗。實驗結果顯示，JSG-2改良土（水灰比為2.53）之單軸壓縮強度qu為3.47至6.12 MPa，低於JSG-1改良土（水灰比為1.0）之qu值，但高於設計所要求之單壓強度0.5 MPa。三軸試驗結果顯示，改良土之凝聚力c = 0.835 MPa、內摩擦角ϕ = 38.6°。本文建議採用拋物線經驗準則，更合理地描述改良土在張應力及低正應力下之破壞包絡線。不論被改良的土層是砂土或是粘土，所形成改良土的滲透係數都非常低，僅有4.8至9.0 × 10^(-7) cm/sec。上述滲透係數與日本JSG協會建議的改良土滲透性範圍k = 10^(-6) ~ 10^(-7) cm/sec大致符合。

關鍵字

內摩擦角 ； 噴射灌漿 ； 滲透係數 ； 改良土 ； 單軸壓縮強度

並列摘要

Mechanical properties of jet-grouted soilcrete drilled from the construction site of Nankang Line of Taipei Rapid Transit Systems project are reported in this article. To prevent damaging adjacent structures, before excavating the shield tunnels, jet grouting was conducted around the proposed tunnel. Twenty days after grouting, cylindrical specimens were drilled from the site and tested in the laboratory. Based on the experimental data it is found that the uniaxial compressive strength qu for JSG-2 soilcrete (w/c = 2.53) varies from 3.47 to 6.12 MPa, which is generally lower than that for JSG-1 soilcrete (w/c = 1.0). The qu values obtained are obviously higher than the design strength 0.5 MPa. Triaxial test results indicate that the cohesion and internal friction angle of JSG-2 soilcrete are 0.835 MPa and 38.6 degrees. It is suggested to describe the failure envelope of soilcrete under low normal stress with an empirical parabolic criterion. The permeability of soilcrete varies from 4.8 to 9.0 × 10^(-7) cm/sec, which is in good agreement with the values recommended by the JSG Association.

並列關鍵字

internal friction angle ； jet grouting ； permeability ； soilcrete ； uniaxial compressive strength