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    基于深度校正的剪切波速度在东北黑土区土层结构识别中的应用研究

    Application of shear wave velocity with depth correction in identifying soil layer structure in black soil covered area, Northeast China

    • 摘要: 在浅层地下结构调查工作中,发现直接利用微动反演所得的剪切波速度进行土层结构划分时,面临着诸多不确定性问题。为了进一步提高剪切波数据在土层结构探测领域的实用性,对剪切波数据开展分析校正工作显得尤为必要。前人在波速深度关系研究方面虽然取得了一定的成果,但这些成果呈现出明显的地域性特征,在识别东北黑土区土层结构时,难以直接借鉴应用。鉴于此,文章以松嫩盆地北部的微动探测反演结果以及钻孔资料为基础,对比分析了剪切波速度与埋深之间的5种回归模型的适用性与准确性,并确定了二次函数模型为最优模型。针对研究区内11种不同类型的土壤,分别构建了剪切波速度与埋深之间的二次函数关系式,并依据关系式确定了不同土壤对应的深度校正量。为了验证模型及校正方法的有效性,文章以壤土作为参考标准,选取2个典型实例进行验证。验证结果表明:二次函数模型能够准确地表达土壤剪切波速度与埋深之间的非线性关系。经过校正后的剪切波速度,与钻孔揭露的壤土分布情况较一致。深度校正,有效削弱了因埋深导致的土壤压实效应所带来的影响,校正后的剪切波速度在土层结构识别方面展现出显著提升的效果和能力。

       

      Abstract: Shallow subsurface investigations utilizing microtremor inversion for shear-wave velocity (Vs) face various uncertainties in delineating soil layer structures. It is essential to analyze and correct data to enhance the practicability of Vs data adopted in soil stratigraphy identification. Previous studies on Vs-depth relationships exhibit obvious regional limitations and are inappropriate for direct application in the Black Soil Region of Northeast China. This study employed microtremor inversion results and borehole data from the northern part of Songnen Basin. After comparing the applicability and accuracy of five regression models for describing the Vs-depth relationship, we identified the quadratic function model as the optimal. Subsequently, we established quadratic regression equations relating Vs to depth for 11 major soil types within the study area, enabling the determination of depth-specific correction values for each soil type. Validation was performed by using two case studies with loam as the reference soil. Results demonstrate that the quadratic function model effectively captures the non-linear relationship between Vs and depth for these soils. After correction, the Vs profiles showed high coincidence with the loam distribution revealed through boreholes. Depth correction substantially mitigates the soil compaction effects induced by burial depth. The corrected Vs values significantly improve the accuracy of soil layer structure identification.

       

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