基于304dB的北欧海相黏土参数空间非均匀变异性研究

Study on non-homogeneous spatial variability of nordic marine clays based on 304dB

由于应力和沉积作用的历史差异,不同场地的岩土类型与性质会有所不同;即使同一场地,在不同位置处的岩土类型及性质亦存在差异。目前普遍采用的均匀随机场模型很难准确表征上述复杂空间变异性,且缺乏原位测试数据的验证。为此,基于国际土力学与岩土工程学会风险评估和管理委员会TC-304所开发和维护的岩土实测参数数据库304dB,对北欧三国挪威、芬兰、瑞典海相黏土参数的空间变异性展开了深入研究。分析比较了北欧三国海相黏土的统计特征参数沿深度变化的异同以及各参数相互影响的物理机制,明确了各参数的空间变异性规律。通过趋势性、涨落性与相关性分析,揭示了北欧三国海相黏土参数均值、标准差以及涨落尺度沿深度均非常数,均值沿深度线性增长,标准差沿深度的变化趋势近似为二次函数,相关函数与间距及位置有关,但随间距增长不会一致收敛。基于综合样本的分层相关性分析,建立了海相黏土参数分层非均匀随机场,该随机场均值为沿深度的线性函数,标准差为在空间变化的随机场,其趋势函数为沿深度的二次函数,不同分层位置处黏土参数可具有不同的均值和标准差初值,各层内参数具有不同涨落尺度。与均匀随机场以及仅考虑均值沿深度线性增长的非均匀场模型相比,所建立的分层非均匀随机场模型可以全面描述海相黏土参数均值、标准差及其相关性沿深度的复杂空间变异性及其非连续变化的分层特性。

Due to historical variations in stress and sedimentation,geotechnical materials exhibit strong spatial variability.This means that the distribution and properties of geotechnical types vary across different sites and even within different locations of the same site.Existing random field models struggle to accurately capture this complex spatial variability and often lack verification with in-situ test data.To address these limitations,this paper focuses on studying the spatial variabilities of marine clay parameters in the three Nordic countries using the open database 304dB developed by the Engineering Practice of Risk Assessment and Management TC-304in the International Society of Soil Mechanics and Geotechnical Engineering(ISSMGE).The paper analyzes and compares the differences and similarities in statistical characteristic parameters of marine clay along depth variations in the three Nordic countries.It also investigates the physical mechanisms of mutual influence between various parameters and clarifies the spatial variability laws of each parameter.Through trend analysis,fluctuation analysis,and correlation analysis,the study reveals that the mean value,standard deviation,and fluctuation scale of marine clay parameters in the three Nordic countries are non-constant along the depth.The mean value increases linearly with depth,while the standard deviation shows an approximate quadratic function variation trend along the depth.The correlation function is dependent on distance and location,but does not converge uniformly with increasing distance.Based on stratification correlation analysis of comprehensive samples,a stratification non-homogeneous random field model of marine clay parameters is established.In this model,the mean value of the random field follows a linear function along the depth,while the standard deviation is a spatially varying random field with a quadratic function trend.Parameters exhibit different mean values,initial standard deviation values,and fluctuation scales at different stratification locations.Each layer displays distinct characteristics of discontinuous variation.Compared to homogeneous random field models and non-homogeneous field models that only consider linear increases in mean value along the depth,the stratification non-homogeneous random field model comprehensively describes the complex spatial variability of mean value,standard deviation,and correlation of marine clay parameters along the depth.It also effectively captures the stratification characteristics of discontinuous variation.