基于CPTU测试的高速公路改扩建新老地基土工程特性评价研究

软土地基上进行高速公路扩建项目面临着极大的挑战,必须对新老地基土体的工程特性进行全面的评价。传统室内试验方法会对土体产生扰动,而且时间长、成本大。孔压静力触探(CPTU)技术作为一种新型的原位测试方法,可以测试锥尖阻力、侧壁摩阻力与孔隙水压力等参数,而且具有多功能、连续性、高精度等优点,在国外得到广泛的应用。采用多功能CPTU技术对京沪高速公路扩建工程新老地基土体进行原位测试,基于承载力理论与孔穴扩张理论分别解译了新老地基土体的应力历史、变形与固结特性参数。研究发现:该方法可以更准确地确定软土层的分布、厚度和深度,可为进一步分析新老路基差异沉降的计算提供科学依据,更好地指导路基拼接相互作用与地基处理的设计和施工。

Evaluation of engineering characteristics of new and old soft soil foundation based on advanced CPTU data

The widening project of highways on soft soil foundation faces great challenges. It is necessary to evaluate the engineering characteristics of the new and old foundation soils comprehensively. The traditional methods in laboratory cause disturbance to the soils, which is long and costly. As a new in-situ testing technology, CPTU, can be used to obtain parameters precisely and continuously including cone tip resistance, sidewall friction and pore water pressure. The multi-functional CPTU technology is used to test the new and old foundation soils of the Beijing-Shanghai Expressway. Based on the bearing capacity theory and the cavity expansion theory, the parameters of the old and new foundation soils are interpreted, such as the stress history, deformation and consolidation. It’s found that the distribution, thickness and depth of soft soil layer can be more determined accurately. In addition, the above-mentioned important engineering parameters can be provided as the scientific evidences for the prediction of differential settlement of old roadbed and the design and construction of subgrade splicing.