风积沙地区静力触探试验(CPT)数值模拟研究

    Numerical simulation on static cone penetration test (CPT) in aeolian sand areas

    • 摘要: 风积沙广泛存在于我国的西部地区,其土质松散、无黏性且含水少的特点十分突出,而静力触探试验(cone penetration test, CPT)作为一种使用范围广、数据质量高的原位测试技术,能够较为简便、准确地获取风积沙地区的土体特性信息。为高效、准确地模拟静力触探试验锥尖贯入过程中的大变形问题,采用一种具有基于网格和颗粒方法的优势的物质点法(material point method, MPM),建立了砂土中静力触探试验数值模型,并通过状态相关莫尔-库仑(state-dependent Mohr-Coulomb)准则,使用相对简单的一套土体参数,来捕捉砂土孔隙比与平均应力之间的状态相关特性。所建立的MPM数值模型首先与良好测试的模型槽试验进行对比,通过贯入过程中锥尖阻力及不同深度径向应力曲线验证了本文所建立模型的准确性。随后改变计算域初始孔隙比来模拟风积沙的松散状态,通过一系列风积沙中静力触探试验数值模拟,探究锥尖贯入阻力随风积沙初始孔隙比的规律。结果表明:锥尖贯入阻力随初始孔隙比的增大而非线性减小,但松沙锥尖贯入阻力稳定值基本不随初始孔隙比发生变化,因此可采用相对节省材料的方法来选取工程设计参数,提高风积沙地区工程建设经济效益。

       

      Abstract: Aeolian sand is widely distributed in western China, characterized by loose, non-cohesive soil and low water content. The static cone penetration test (CPT), as a widely used and high-quality in-situ testing technique, can easily and accurately obtain soil characteristic information in aeolian sand areas. This study aims to efficiently and accurately simulate the large deformation problem during the static cone penetration process of the cone penetration tests. A material point method (MPM) that combines the advantages of the grid and particle methods is adopted to establish a numerical model for the cone penetration tests in sandy soil. The state-dependent Mohr-Coulomb criterion is used to capture the state-dependent characteristics between the void ratio and the mean stress using a relatively simple set of soil parameters. The established MPM numerical simulation model is first compared with a well-tested calibration chamber test, and the accuracy of the established model is verified through the cone penetration resistance and radial stress curves at different depths during penetration. Subsequently, the initial void ratio of the computational domain is changed to simulate the loose state of aeolian sand. Through a series of cone penetration tests in aeolian sand, numerical simulations are conducted to explore the relationship between the cone penetration resistance and the initial void ratio of aeolian sand. The results indicate that the penetration resistance decreases nonlinearly with the increase of the initial void ratio, but the stable value of the penetration resistance in loose sand does not change with the initial void ratio. Therefore, a relative material saving method can be used to select the design parameters in engineering, improving the economic benefits of engineering construction in aeolian sand areas.

       

    /

    返回文章
    返回