波速测试与标贯试验在预估砂土密度中的应用研究

Study on Application of Wave Velocity Test and Standard Penetration Test in Estimating Sand Densities

原状砂土的易扰动性和试验试样的不易获取和制备,往往不能控制其天然含水率的变化,难于获取砂土的天然密度参数,而波速测试和标贯试验作为高效的原位测试方法,在预估砂土密度方面具有明显优势。以赤壁某跨江通道的岩土工程勘察项目为例,采用剪切波试验和标准贯入试验方法,对场区深厚砂层进行原位数据采集,并用高质量取样方法对场区砂层进行取样和室内密度试验,通过获取砂土天然密度和干密度建立剪切波速和标贯击数与天然密度和干密度关系。研究表明:(1)剪切波速度和标贯击数与砂土的天然密度和干密度具有较好的拟合关系,可以用统一的幂指数关系表达;(2)采用归一化一致性和累计频率拟合公式进行可靠性和准确性验证,表明所有提出的方程均具有良好的预测性能,利用这些关系估算砂土的天然密度和干密度具有可行性。

As a result of the easy disturbance of undistributed sand and the difficulty of obtaining and preparing test samples,it is often impossible to control the change of natural moisture content and hard to obtain the natural density parameters of the sand.As efficient in-situ test methods,wave velocity testing and standard penetration test have obvious advantages in predicting sand density.Taking the geotechnical engineering investigation project of a river-crossing channel in Chibi as an example,the in-situ data of the deep sand layer in the filed area were collected through shear wave testing and standard penetration test.The sand layer in the area was sampled and tested in laboratory by high-quality sampling method.By obtaining the natural density and dry density of the sand,the relationship between shear wave velocity and standard penetration test blow count with natural density and dry density is established.The research results show that:(1)Shear wave velocity and standard penetration test blow count have a good fitting relationship with the natural density and dry density of sand,which can be expressed by a unified power exponential relation;(2)The reliability and accuracy are verified by normalized consistency and cumulative frequency fitting formula,which shows that the proposed equations have good prediction performance,and it is feasible to adopt the relations to the prediction of natural density and dry density of sand.