研究大方量砂土的改良，综合考虑材料易得性、工程造价需求，采用黏粒含量较低的黄土对砂土进行改良，并深入探究应力场与渗流场的耦合作用，为实际工程中类似工况提供一种相对经济而且有效的改良方法。以晋中地区砂土为研究对象，借助应力应变控制式三轴剪切渗透试验仪，探究黄土对砂土应力-渗流耦合关系的影响，分析多因素耦合下砂土强度和渗透性的变化。结果表明：在剪切过程中，砂土的强度随含水率增大而减小，随围压的增大而减小，其受黄土掺量影响最大；砂土渗透性随应力变化而变化，渗透系数随着轴向应力的增大而减小，且砂土渗透系数随着黄土掺量的增大出现数量级的下降。根据砂土应力-渗流耦合试验所提供的数据分析，证明掺入当地黄土对于改善砂土性质的有效性。尽管当地黄土和黏土在黏性上有一定差异，但其在强度、渗透性等方面的特性依旧能够取得类似的改良效果。

Studying the improvement of large volumes of sandy soil is one of the important topics in the current road engineering field. In order to comprehensively consider the availability of materials and the requirements of engineering cost, loess with a low clay content was used to improve sandy soil. This choice is based on the fact that loess is widely available in many areas and is relatively cheap, and its soil properties can also meet the needs of engineering improvement. The main purpose of this study is to deeply explore the coupling effect of stress field and seepage field. It should be noted that the volume of silt sand that needs to be improved in the project is often large, and the amount of high-quality clay soil in the region is small. Whether it is possible to use soil with low viscosity to improve silt sand is of great research significance. The sand in Jinzhong area was taken as the research object, and uses a stress-strain controlled triaxial shear permeability tester to explore in detail the influence of loess on the stress-seepage coupling relationship of sand. During the test, by changing variables such as the water content, confining pressure and loess content of the sand, the changes in the strength and permeability of the sand under the conditions of multi-factor coupling were systematically analyzed. The test results show that during the shearing process, the strength of sand shows a decreasing trend as the moisture content increases. Specifically, as the moisture content increases, the friction between sand particles decreases, resulting in a decrease in its overall strength. At the same time, the strength of sand also decreases with the increase of confining pressure. This may be because as the confining pressure increases, the porosity between sand particles decreases, resulting in an increase in the binding force between particles, resulting in a decrease in the shear strength. In addition, the study also found that the strength of sand soil is most affected by the amount of loess. When the loess content increases, the strength of the sand soil increases significantly, which shows that the addition of loess has a positive effect on improving the mechanical properties of the sand soil. Test results on the permeability of sand show that it changes significantly with changes in stress. In particular, the permeability coefficient decreases with increasing axial stress. This phenomenon can be explained by the fact that the increase in axial stress further compresses the pores between sand particles, thereby reducing the channels for water flow, resulting in a decrease in permeability. More importantly, experimental data also show that the permeability coefficient of sand decreases by an order of magnitude as the loess content increases. This result shows that the addition of loess significantly improves the permeability properties of sand, making it better able to prevent leakage and water intrusion in practical engineering applications. By analyzing the data provided by the stress-seepage coupling test of sand, the effectiveness of adding local loess to improve the properties of sand was proved. Although there are certain differences in viscosity between local loess and traditionally used clay, the results show that loess can still achieve similar improvement effects in key indicators such as strength and permeability. This provides a solid theoretical basis and practical basis for using loess to improve sand in actual engineering. In summary, this study proved the feasibility and effectiveness of using local loess to improve sand through detailed experiments and data analysis. This not only provides a reliable technical solution for engineering practice in Jinzhong, but also provides a valuable reference for sand improvement in other similar areas. It is expected that the performance changes of loess-improved sand under different stress conditions and environmental factors will be further studied to provide more comprehensive technical support for applications in the field of civil engineering.