冻融引起黄土隧道洞口段应力变形分析

STRESS AND DEFORMATION ANALYSIS OF LOESS TUNNEL ENTRANCE CAUSED BY FREEZE-THAW

通过试验获得了原状黄土冻融后的强度参数,并利用有限元方法分析了冻融对黄土隧道洞口段应力及变形的影响。分析结果表明,在冻融作用下,覆土厚度和冻融次数均会对拱顶位移和拱顶上部土体水平压应力产生影响。覆土厚度越大,隧道在开挖和经历冻融后,拱顶沉降也越大;且冻融第1次后对拱顶沉降影响最大。拱顶上部土体水平压应力最大值随覆土厚度的增加而增大;距拱顶较近土体的水平压应力随冻融次数增加逐渐减小,距拱顶较远土体的水平压应力值随冻融次数增加逐渐增大。

Strength parameters obtained after freeze-thaw of intact loess through the test and this pa- per analyzed the factor of freeze-thaw effect on stress and deformation of loess tunnel entrance hy finite element method. The analysis results show that thickness of the overlying soil and freeze-thaw times will influence displacement of the vault and horizontal compressive stress of the vault upper soil mass under function of freeze-thaw. The greater thickness of the overlying soil, the bigger settlement of the vault ap- pears after tunnle excavation and experience of freeze-thaw and the greatest influence appears after the first time of freeze-thaw. The maximum horizontal compressive stress of the vault upper soil mass increa- ses with increasing of thickness of the overlying soil; horizontal compressive stress of soil mass near the vault gradually reduces with freeze-thaw numbers increase, but the stress of soil mass far from the vault gradually increases with freeze-thaw numbers increase.