原状土地基石灰土路堤离心模型试验

Centrifuge Modeling of Embankment with Lime-stabilized Soil as Backfill on Undisturbed Clay

摘要:

对原状软土地基石灰土路堤进行了离心模型试验，分析了试验过程中拍摄的模型图片、位移计测得的路堤和地基表面位移，以及模型地基侧面的标记点位移等值线图.分析结果表明，原状软土地基上的石灰土路堤在2~4 m的堆载过程中由于地基不均匀沉降开始断裂；地基中最大水平位移增量Δδmax与路堤中心下地基沉降增量ΔS之比值在4~6 m的路堤堆载阶段发生突变，预示地基趋于失稳，这与离心模型试验观察结果及采用不排水剪指标的太沙基地基承载力计算结果一致；鉴于石灰土的脆性和低抗拉强度，在实际软土地基石灰土路堤工程中可采用低于2 m的低路堤形式，也可在石灰土路堤中采用加筋的方式来提高其整体性、抗拉强度和减小地基的不均匀沉降量.

Abstract:

A centrifuge model test was made on an embankment with lime-stabilized soil as backfill on undisturbed soft soil,and an analysis was made of the in-flight photographs, displacements measured by displacement sensors installed on the surface of embankment and ground, and displacement contour lines obtained from the markers installed on the front face of the clay.The results show a vertical crack occurs to the embankment during its construction from the height of 2~4 m due to differential displacement of subsoil. The ratio of the maximum lateral displacement increment in the subsoil to the ground settlement increment at the embankment center changes significantly during the loading stage of the height of 4~6 m in prototype, indicating the subsoil tends to fail. This finding is consistent with the observations of the centrifuge test and the computation result from Terzaghi’s bearing capacity theory using undrained shear strength. In view of the brittle behavior and low tensile strength of embankment with lime-stabilized soil, low embankment of the height lower than 2 m is recommended for practical projects.Reinforcement in the embankment is also recommended for improving the integrity and tensile strength and reduce the differential displacement of subsoil as well.