黄土丘陵沟壑区压实回填土地基沉降计算方法

沟谷型黄土高填方工程地基沉降控制问题既是重点也是难点,针对黄土丘陵沟壑区压实回填土地基沉降计算方法研究较少。通过室内人工配制试样与回填场地原位探井取样开展了一系列室内高、中、低压侧限压缩固结试验,探究了压实回填土的变形特性,基于割线模量法与分层总和法研究路径的不同提出了一种改进的沉降计算方法,对比分析了填筑体在不同计算方法下的最终沉降量差异。试验结果发现,采用基于Gunary模型非线性垂直压应力-压应变关系表示的割线模量法,计算所得的最终沉降量数值比分层总和法计算值偏小,两者偏差在4.8%之内。压实回填试验场地的实测压实度基本稳定在(70±5)%,通过提出的计算方法预测回填场地33 m深填方填筑体在水环境未变化时产生的总压缩固结沉降变形量为1523.2 mm,填方区的地基沉降量非常大,填方区的基础设施建设应在地基充分固结变形稳定后,同时,高填方施工应严格控制压实度,努力提升施工质量。该计算方法是对割线模量法沉降计算体系的有益补充,其计算结果可供实际工程建设参考。

Method for calculating foundation settlement of compacted backfill in hilly and gully regions of loess

The problem of foundation settlement control of high loess filled projects is important and difficult. Because of the lack of researches on methods for calculating settlement of compacted backfill foundation of high embankments in hilly and gully regions of loess, a series of indoor confined consolidation experiments using indoor artificial test samples and field samples are carried out. The deformation characteristics of compacted backfill loess are studied. Based on the different research paths of the secant modulus method and the stratified summation method, a modified foundation settlement method is proposed. The differences of the final settlements under different methods are compared and analyzed. The results show that the calculated values by the secant modulus method based on the vertical stress - strain relation of Gunary Model are smaller than those based on the stratified method, and the difference range is within 4.8%. The compactness of backfill loess is basically stable in (70±5) %. In fact, it is a very low compactness. The final compression and consolidation settlement of the 33 m-deep test site is predicted by the proposed method, and it is 1523.2 mm. The infrastructure construction in backfill area should be carried out after full consolidation of the foundation. In the meanwhile, the compactness should be strictly controlled during construction of high embankments, and the quality of construction should be improved. The new foundation settlement is a useful supplement to the computational system of secant modulus method in settlement calculation, and the calculated results are available to guide the construction and design of practical projects.