A vertical tube surface drip irrigation system was designed to address the damage caused by soil drought and high surface temperature to sand-fixing seedlings in a plant sand-fixation area. Numerical simulation and experimental verification were used to study soil water movement with vertical tube infiltration and surface drip irrigation for four aeolian sandy soils with different hydraulic conductivity (Ks), drip discharge (Q), vertical tube diameter (D), and vertical tube buried depth (B). The results show that a power function relationship exists between the soil-stable infiltration rate (if) and Ks, D, and B given the condition of vertical tube water accumulated infiltration, and its coefficient is 0.17. The power function indices of Ks, D, and B are 0.87, 1.89, and -0.37, respectively. The if can be used to determine the maximum drip discharge (Qmax) of the dripper in the vertical tube to ensure that the sand-fixing plants are not submerged during drip irrigation through the vertical tube (Qmax=if). The wetting front transport distance in the three directions increased with increasing Ks and Q but decreased with increasing D and B. After determining the time required for water to reach the bottom of the vertical tube, an estimation model of soil wetting body transport for vertical tube surface drip irrigation, including Ks, Q, D, and B, was constructed. Compared with the experimental data, the root mean square error (RMSE) is between 0.17 and 0.42 cm, and the Nash-Sutcliffe efficiency (NSE) is at least 0.88. Therefore, the model is appropriate and can provide valuable practical tools for the design of vertical tube surface drip irrigation in different plant sand fixation areas. A surface drip irrigation system and pipe protection technology were combined to form a vertical tube surface drip irrigation system to address the damage caused by soil drought and high surface temperature to sand-fixing seedlings. However, this irrigation technology has the problem that it is difficult to quantify the matching of drip discharge and pipe parameters (vertical tube diameter and burial depth), wetted soil volume, and plant roots due to the single soil sample used in the laboratory experiments. This paper considers the influence of soil differences in diverse plant sand-fixing areas and establishes a stable infiltration rate model to determine the maximum drip discharge. Additionally, a soil wetted volume prediction model was developed by combining HYDRUS-2D simulations and experimental verification. The model is simple and has high prediction accuracy, which is convenient for designers to determine the appropriate vertical tube parameters for different plant sand-fixation areas.

Determining a rational mix ratio for lime -fly ash -stabilized loess (LFSL) can achieve multiple benefits of economy, environmental protection, and engineering quality improvement. This research was designed to optimize the mix ratios of LFSL applied in the pavement structure, subgrade, slopes, and foundations by conducting the unconfined compressive strength ( UCS ) test, California bearing ratio ( CBR ) test, resilient moduli ( M R ) test, triaxial test and uniaxial consolidation test on LFSL and lime -stabilized loess (LSL). Combined with the initial consumption of lime (ICL) test result and relevant specifications, the optimized mix ratios are as follows: 2% lime + 11.82% fly ash and 2% lime + 3.95% fly ash can reach the strength requirement of road base and subbase, respectively; 2% lime + 3.84% fly ash in building foundations and subgrade and 2% lime + 3.55% fly ash in slopes can reach the equal improvement effect of the LSL with 8% lime content. Three -factor comprehensive models were established and fitted in well with the experimental results of the LFSL with 2% lime content. Moreover, the development of correlations between UCS and other mechanical indices offers a shortcut for engineering property estimation. Finally, based on the abundant literature on LSL, another approach to estimating engineering quality was proposed for the LFSL with 2% lime content, which enhances the universality and practicability of the estimation models further.