弥勒非低矮路基超固结膨胀土地基沉降特征

为研究非低矮路基下超固结原状膨胀土地基沉降特征，针对弥勒超固结膨胀土地区路基下地基的物理力学特性与沉降变形特征，开展了一系列原状膨胀土分级连续加载K₀固结试验以及现场路基填筑试验，并长期监测路基下地表沉降与路基下地基分层沉降。对比分析天然地基与CFG桩加固地基的沉降特征，地基中的超固结土与正常固结土的分界面深度随路基荷载增大的变化规律及其对地基沉降量的影响。分别采用正常固结法和超固结法计算地基沉降量，并与实测结果进行对比分析，对沉降计算方法进行了深入讨论。研究结果表明：CFG桩加固处理深度应超过超固结土层分布深度，否则与天然地基相比，控制沉降的效果并不明显；超固结沉降计算方法的计算精度明显高于目前设计常用的正常固结沉降计算方法（超固结计算方法的修正系数为0.531，正常固结计算方法的修正系数为0.351），超固结算法-正常固结算法修正系数比随土层深度递减的趋势可用于反映超固结土层的加固处理情况；在路基工程设计中，对于路基荷载下的超固结膨胀土地基，建议采用超固结法沉降计算方法进行沉降分析；在地基加固处理时也应充分利用原状膨胀土的超固结特性，从而在该类地基加固设计中有效降低工程成本。

Settlement Characteristics of Expansive Soil Foundation Under Non-low Embankment of Mile

The objective of this research is to study the settlement characteristics of intact overconsolidated expansive clays with under a non-low embankment. Based on the deformation characteristics of the Mile overconsolidated physical and mechanical properties of the foundation soil subgrade under expansion and settlement, a series of undisturbed expansive soil classification K₀ continuous loading consolidation tests and subgrade filling tests were performed, and the long-term settlement of the subgrade surface and settlement of a subgrade under the subgrade were monitored. The settlement characteristics of the natural foundation and CFG (The abbreviation of Cement Fly-ash Gravel, the same below) piles-reinforced foundation were compared and analyzed. The change law of the depth of the interface between the overconsolidated soil and normal consolidated soil with the increase in the subgrade load and its influence on the settlement of the foundation were analyzed. The settlement of the foundation was calculated by the normal consolidation method and over-consolidation method, and the results were compared with the measured results. The settlement calculation method is discussed in depth. The results show that the reinforcement depth of the CFG pile should exceed the depth of the overconsolidation soil layer, otherwise, the effect of the settlement control is not obvious compared with the natural foundation. The precision of the method of overconsolidation settlement calculation is significantly higher than the method of normal consolidation settlement calculation, which is commonly used in current designs. (The modified coefficient of the overconsolidation method is 0.531 and of the normal consolidation method is 0.351) The decrease in the modified coefficient ratios of the overconsolidation and normal consolidation calculation methods with the soil depth can be used to reflect the reinforcement of the foundation in the overconsolidated soil layer. In the design of subgrade engineering, for an overconsolidated expansive soil foundation under a subgrade load, adoption of the overconsolidation method as the settlement calculation method is suggested to analyze the settlement. For the foundation reinforcement treatment, the excess consolidation property of the undisturbed expansive soil should be fully utilized, so that the engineering cost can be effectively reduced in the design of the foundation reinforcement.