The use of a sunken lawn is an emerging Low Impact Development (LID) technique to effectively control storm runoffs. However, the random infiltration of rainwater that occurs due to the construction of a sunken lawn in an area of collapsible loess seriously threatens the safety of buildings around it. Setting up a vertical soil sand layer (VSSL) structure next to a sunken lawn as an anti-permeate method has been proposed in this study. To analyze the lateral anti-seepage effects of a VSSL, a sunken lawn model around a building was established based on soil physical parameters, and water seepage in the sunken lawn was investigated using a infiltration experiment and HYDRUS-2D software. The results show that the anti-seepage effects of a VSSL can significantly reduce the average wetting front migration length and water content at the observation points behind the sand layer. The Nash-Sutcliff Efficiency (NSE) index was used to evaluate the accuracy and reliability of the HYDRUS-2D model. The values of the NSE index obtained were greater than 0.82 (varied between 0.82 and 0.98) which confirmed the applicability of the HYDRUS-2D software in accurately describing the hydraulic behavior of the lateral anti-seepage effects of the VSSL in a sunken lawn. Simulation infiltration tests showed that, on the side of the VSSL, the wetting front migration length was reduced by 55.5% on average, and the water content of the observation points behind the sand layer was reduced by 40.5%, increasing the stability of the loess around the building infrastructure. The results are of value in practical applications, such as for devising engineering or non-engineering measures to avoid loess collapsibility around sunken lawns.

下沉式草坪的使用是一种新兴的低影响发展（LID）技术，可有效控制暴雨径流。然而，由于在可湿陷的黄土地区建造了凹陷的草坪而引起的雨水的随机渗透严重威胁着周围建筑物的安全。这项研究提出了在沉没的草坪旁建立垂直土壤沙层（VSSL）结构作为一种防渗透方法。为了分析VSSL的横向防渗效果，基于土壤物理参数建立了建筑物周围的凹陷草坪模型，并使用渗透实验和HYDRUS-2D软件研究了凹陷草坪中的渗水情况。结果表明，VSSL的防渗作用可以显着降低沙层后面观测点的平均润湿锋迁移长度和含水量。Nash-Sutcliff效率（NSE）指数用于评估HYDRUS-2D模型的准确性和可靠性。获得的NSE指数值大于0.82（在0.82和0.98之间变化），这证实了HYDRUS-2D软件在准确描述下沉草坪中VSSL的侧向防渗作用的水力行为方面的适用性。模拟入渗试验表明，在VSSL侧，湿润锋线前移长度平均减少了55.5％，沙层后面的观测点的水分减少了40.5％，提高建筑基础设施周围黄土的稳定性。该结果在实际应用中具有价值，例如用于设计工程或非工程措施以避免黄土在凹陷的草坪周围塌陷。