湿陷性黄土地区海绵城市建设湿陷性风险模拟评估研究

在湿陷性黄土地区开展雨水集中下渗的海绵城市建设面临着湿陷变形的风险,以黄土湿陷性较为严重的西咸新区空港新城临空产业区为例,采用数值模拟的方法模拟了研究区湿陷性黄土在不同设计降雨情况下的雨水集中入渗后的湿陷情况。应用GAST模型计算雨洪过程,并将降雨量下渗过程作为边界条件输入Midas GTS/NX软件来模拟黄土基础变形情况。通过分析5个典型黄土区因降雨下渗导致的湿陷量,发现其等级为Ⅱ级及以上,其中最严重情况下的雨水下渗深度为5.02~6.51 m,总湿陷量和自重湿陷量分别为468.18~1015.56 mm和88.99~239.03 mm,湿陷等级为Ⅲ级。可见局部集中下渗会导致较高的湿陷风险,故建议在湿陷性黄土地区海绵城市建设中应进行量化评估并合理规避湿陷风险。

Study on simulation assessment of collapsible risk of sponge city construction in collapsible loess area

The sponge city construction in areas with collapsible loess is faced with the risk of collapse deformation. Taking the airport industrial zone of Airport New Town in Xixian New Area as an example, the collapsibility of collapsible loess under different rainfall conditions was numerically simulated. The rainfall flood process was calculated using GPU accelerated surface water flow and transport (GAST) model, and the rainfall infiltration process was introduced to Midas GTS/NX software as the boundary condition to simulate the deformation of loess foundation. Based on the analysis of five typical loess regions with collapse deformation, it is found that the collapsibility of the five regions are all classified as grade II and above. The depth of rainwater infiltration under the most serious condition is 5.02 ~ 6.51 m, the total collapsibility and dead weight collapsibility are 468.18~1 015.56 mm and 88.99~239.03 mm respectively, which is classified as grade III collapsibility. Therefore, it is suggested that quantitative assessment and reasonable avoidance of collapsible risk should be carried out in the construction of sponge city in collapsible loess area.