Three-dimensional (3D) geotechnical site stratification is of vital importance in geotechnical practice. In this study, a set of methods for 3D site stratification based on CPTu measurements of New Zealand Geotechnical Database (NZGD) sites is proposed. One-dimensional (1D) soil stratification at discrete CPTu points is first conducted and then interpolated in 3D to achieve 3D site stratification. 1D soil stratification is achieved through a proposed soil classification model combined with a proposed soil layer boundary identification method, which achieves a correct soil profile length identification rate of 93%. The soil classification machine learning model classifies the soil within NZGD into three types, i.e. Gravel, Sand, and Silt, and is able to reflect the fines content for silty sand. The model innovatively incorporates local variation information of CPTu curves in the input for a random forest algorithm to significantly improve identification accuracy to over 90%. Accurately locating soil layer boundaries is achieved through proposing a modified WTMM boundary identification method. 3D site stratification is then realized through 3D interpolation of 1D stratification at discrete CPTu points using a generalized regression neural network (GRNN) method. The 3D site stratification method is validated for two independent geotechnical sites within NZGD, exhibiting the effectiveness of the proposed set of methods.

三维 (3D) 岩土工程场地分层在岩土工程实践中至关重要。在这项研究中，提出了一套基于新西兰岩土数据库 (NZGD) 站点 CPTu 测量值的 3D 站点分层方法。首先进行离散 CPTu 点的一维 (1D) 土壤分层，然后在 3D 中进行插值以实现 3D 场地分层。通过提出的土壤分类模型结合提出的土层边界识别方法实现一维土壤分层，实现了93%的正确土壤剖面长度识别率。土壤分类机器学习模型将NZGD内的土壤分为砾石、沙子和粉土三种类型，能够反映粉砂的细粒含量。该模型创新性地将CPTu曲线的局部变化信息纳入随机森林算法的输入中，识别准确率显着提高至90%以上。通过提出一种改进的WTMM边界识别方法，实现了准确定位土层边界。然后使用广义回归神经网络 (GRNN) 方法通过离散 CPTu 点处的 1D 分层的 3D 插值来实现 3D 站点分层。3D 场地分层方法在 NZGD 内的两个独立岩土工程场地进行了验证，展示了所提议方法集的有效性。通过提出一种改进的WTMM边界识别方法，实现了准确定位土层边界。然后使用广义回归神经网络 (GRNN) 方法通过离散 CPTu 点处的 1D 分层的 3D 插值来实现 3D 站点分层。3D 场地分层方法在 NZGD 内的两个独立岩土工程场地进行了验证，展示了所提议方法集的有效性。通过提出一种改进的WTMM边界识别方法，实现了准确定位土层边界。然后使用广义回归神经网络 (GRNN) 方法通过离散 CPTu 点处的 1D 分层的 3D 插值来实现 3D 站点分层。3D 场地分层方法在 NZGD 内的两个独立岩土工程场地进行了验证，展示了所提议方法集的有效性。