Purpose

Permeability is one of the primary concerns in geotechnical engineering research. The permeability coefficient, the most significant parameter defining permeability, has a significant impact on the mechanical and physical properties of the soil by virtue of its value. Because soil is a bulk material and its internal seepage channels are intricate, it is challenging to accurately describe those using straightforward physical parameters. As a result, the models currently in use for calculating the coefficient of permeability of soils are mostly skewed towards empirical statistics and have issues with uneven magnitude and ambiguous physical significance. Thus, one of the key scientific issues in the field of geotechnical engineering is the development of a permeability coefficient estimate model that can characterize the seepage channel.

Methods

Based on the idea of hydraulic radius in circular pipe flow, this paper establishes the calculation method of the equivalent hydraulic diameter by analyzing the microstructure of the soil body and proposes the idea of equivalent hydraulic force inside the soil body, taking into account factors such as granular gradation, dry density, and specific gravity of solid particle. Furthermore, a theoretical model based on the equivalent hydraulic diameter has been constructed for the permeability coefficient of the soil body, by introducing the coefficient of fluid dynamic viscous and the water gravity. In order to assess the accuracy and validity of the equivalent hydraulic diameter and the model of soil permeability coefficient estimation, permeability tests were designed and the results of undisturbed loess, single particle size quartz sand, and multi-grain-size quartz sand combinations were obtained. The results of the estimated model, the traditional estimated model, and the permeability coefficient of the tests were compared and analyzed.

Results and conclusions

The findings indicate a square relationship between the permeability coefficient and the equivalent hydraulic diameter and a correlation coefficient of more than 97% between the equivalent hydraulic diameter calculation results and the measured permeability coefficient results; the error analysis results demonstrate that the equivalent hydraulic diameter calculation results can meet the permeability test error range. This paper presents an estimation model for the soil permeability coefficient that is universally applicable to a wide range of particle sizes (0.002 to 2 mm). It is compared with experimental test results, Terzaghi formula, Hazen formula, and Amer formula. The results demonstrate that the model developed in this paper has a higher degree of agreement with the experimental results.

中文翻译：

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宽范围粒径土壤渗透系数的经验关系

目的

渗透性是岩土工程研究的主要关注点之一。渗透系数是定义渗透性的最重要参数，其值对土体的力学和物理性质具有重大影响。由于土壤是一种散装材料，其内部渗流通道非常复杂，因此使用简单的物理参数来准确描述这些渗流通道具有挑战性。因此，目前用于计算土壤渗透系数的模型大多偏向于经验统计，存在大小不均和物理意义不明确的问题。因此，岩土工程领域的关键科学问题之一是建立能够表征渗流通道的渗透系数估计模型。

方法

基于圆管流水力半径的思想，通过分析土体的微观结构，建立了等效水力直径的计算方法，提出了土体内部等效水力的思想，并考虑了以下因素：颗粒级配、干密度、固体颗粒比重。进一步引入流体动力粘性系数和水重力，建立了基于等效水力直径的土体渗透系数理论模型。为了评价等效水力直径和土壤渗透系数估算模型的准确性和有效性，设计了原状黄土、单粒级石英砂和多粒级石英砂组合的渗透性试验结果。 。对估算模型、传统估算模型以及试验渗透系数的结果进行了比较分析。

结果和结论

结果表明，渗透系数与等效水力直径呈平方关系，等效水力直径计算结果与实测渗透系数结果相关系数达97%以上；误差分析结果表明，等效水力直径计算结果满足渗透率测试误差范围。本文提出了一种普遍适用于各种粒径（0.002 至 2 mm）的土壤渗透系数估计模型。与实验测试结果、Terzaghi公式、Hazen公式、Amer公式进行了比较。结果表明，本文建立的模型与实验结果具有较高的吻合度。