长大明挖隧道回填土堆载预压研究

堆载预压是处理软弱地基的一种有效方法,可以加快软弱地基的固结沉降。为了研究在明洞回填土地段采用堆载预压加快固结沉降的可行性,以京张高铁东花园隧道为工程背景,通过有限元软件对结构覆土进行验算,得出不同衬砌类型明洞所能承受的最大覆土厚度,利用改进高木俊介法对明洞回填土堆载预压进行计算,得出不同堆载高度下回填土的固结度。研究结果表明:(1)在堆载条件下,回填土的固结度随着覆土厚度的增大而呈幂函数形式减小,且固结度受堆载高度的影响不大。(2)在相同的覆土条件下,堆载高度对保留土高度影响较小;(3)堆载预压可以加快明洞回填土的固结沉降,是一个比较可行的方案。

Study on Surcharge Preloading of Backfill for Long and Large Open-excavated Tunnel

Surcharge preloading is an effective method to deal with soft foundation,which can accelerate the consolidation settlement of soft foundation. In order to study the feasibility of using surcharge preloading to accelerate consolidation settlement of backfill soil in open-excavated tunnel,taking the Donghuayuan Tunnel of Beijing-Zhangjiakou High-speed Railway as the engineering background,the structural overburden is checked by finite element software,and the maximum overburden thickness of open-excavated tunnel with different lining types is obtained. The surcharge preloading of backfill for open-excavated tunnel is studied by improved Takagi Shunsuke method,the consolidation degree of backfill under different surcharge loading height is obtained. The results show that:( 1) Under the condition of surcharge loading,the consolidation degree of backfill decreases in power function form with the increase of the thickness of overburden soil,and the surcharge loading height has little effect on the consolidation degree.( 2) Under the same conditions of overburden soil,the surcharge loading height has little effect on the height of the retained soil;( 3) Surcharge preloading can accelerate the consolidation settlement of backfill in open-excavated tunnel,which is a feasible scheme.