武汉地区沙漏型岩溶塌陷数值分析与模型试验研究

隧道穿越沙漏型岩溶地质时，岩溶处理范围直接影响工程安全和投资。为量化计算岩溶处理范围进行岩溶塌陷角的分析和研究，首先，采用模型试验模拟岩溶塌陷过程,验证饱和砂性土渗流液化塌陷机制，定量研究砂层漏失量和塌陷角大小，测算出塌陷角为35.8°； 然后，通过5种工况下的岩溶塌陷过程模拟分析隧道变形形态，结合隧道变形控制标准确定隧道与溶洞的最小安全距离，反算出塌陷角为33.9°； 最后，对比分析模型试验和数值计算得到的岩溶塌陷角大小，得出沙漏型岩溶塌陷角与砂土内摩擦角近似的结论，塌陷角取值可在内摩擦角的基础上加1~3°。将研究结果应用在武汉地铁6号线沙漏型岩溶治理中，取塌陷角为35°计算岩溶处理范围，按此方案实施后盾构顺利穿越岩溶区。

Numerical Analysis and Model Test of Hourglass shaped Karst Collapse in Wuhan Area

When the tunnel passes through the hourglass shaped karst in Wuhan area, the karst treatment range will directly affect the project safety and investment. The analysis and research of karst collapse angle are carried out to quantify the karst treatment area. Firstly, the model test is adopted to simulate the process of karst collapse to verify the mechanism of seepage liquefaction collapse of saturated sandy soil; the sand loss and collapse angle are researched quantitatively; and the collapse angle is calculated to be 35.8°. And then, the deformation morphology of the tunnel is analyzed by numerical simulation of karst collapse process under 5 working conditions; the minimum safety distance between tunnel and karst cave is determined based on the tunnel deformation control standards, and the karst collapse angle is calculated to be 33.9 °. Finally, comparison is made on karst collapse angle between model test and numerical calculation, and the conclusion that the collapse angle of hourglass shaped karst is similar to the friction angle of sand soil and the collapse angle is 1 ~ 3 ° larger than internal friction angle is obtained. The research results are applied to the hourglass shaped karst treatment of Wuhan Metro Line 6, and the collapse angle is taken as 35° to calculate the karst treatment range. According to this scheme, the shield passed through the karst area smoothly.