盾构施工扰动下软土的不同应力路径试验研究

Experimental Study on Different Stress Paths of Soft Soil Disturbed by Shield Construction

依托上海地铁12号线与13号线盾构开挖工程,根据盾构施工周边不同区域内土体的扰动特点,通过一系列不同应力路径下上海第<5>层软土固结不排水三轴试验,分析比较了盾构施工扰动引起的软土中孔压、应力状态变化关系。结果表明:不同应力路径下土体孔压在小应变范围内,很快发生明显变化,应变增大后,孔压稳定。相比压缩应力路径下的土体强度,拉伸路径下的强度较小,同时不同应力路径下的土体屈服时应变均较小。

Relying on shield excavation works of Subway Line No. 12 and No. 13 in Shanghai, the triaxial un-drained shear tests were conducted under various types of stress paths with 〈 5 〉 layer soft soil in Shanghai based on disturbance properties around tunnel, and the characteristics of pore pressure and stress -axial strain relation under different stress paths were analyzed and compared. The results show that the change of pore pressure under different stress paths is obvious and quick in the small strain range, and the change tends to be stable with the increase of strain. The soil strength on compressive stress paths is greater than that on tensile stress paths and that axial strain on different stress path are all smaller than those on standard triaxial test when the soil yields.