Q2、Q3黄土深堑中高填方地基变形规律离心模型试验研究

采用大尺寸原状黄土与重塑黄土联合制作模型，针对Q2、Q3黄土深堑中超高填方地基在天然含水率及饱和状态时的沉降变形规律开展大型离心模型试验研究，系统模拟了超高黄土填方地基在施工期及工后期的变形规律。结果表明：此类高填方地基的施工期沉降变形是总变形量主要组成部分；地基填筑完毕后表面沉槽轮廓清晰，填筑过程中沉降速率随施工填方高度增加而增大，沉降变形中部大、两侧小，且填方体与原地基结合部位的变形缓坡较陡坡一侧小；天然状态下的地基整体沉降变形较小，差异变形量较大，饱和状态下的地基沉降变形增大，差异变形量较小，稳定性较差，差异变形使得原地基与填方体极易发生错动开裂。根据模型试验的分析规律，建议此类地基施工过程中宜对填方体与原地基接触带进行处理，以改善填方体约束条件，同时，填筑完工前可预留一定高度，待前期变形基本完成后，再施工至设计标高，以防止过大差异变形导致的工后开裂。

A centrifugal test study of the deformation of high backfill foundation in deep ravine of Q_2 and Q_3 loess

The settlement of high backfill foundation in deep ravine of Q2 and Q3 loess under natural moisture content and saturated conditions was investigated based on the centrifuge testing. A large-scale centrifugal model test was carried out to simulate the behaviors of the high backfill foundation in its construction and post-construction periods. In this test, the intact loess and disturbed loess were selected as testing materials. It is shown that the settlement deformation of the high backfill foundation mainly occurs in the construction period, and the settlement rate increases with the filling height. After the test, the settlement trough can be clearly seen on the top of the foundation. The maximum settlement occurs in the middle of the filling body. The deformation on the gentle slope with the joint of the filling body and the original foundation is smaller than that on the steep slope. Under the natural moisture content, the total settlement is small, whereas the differential settlement is large. In contrast, the deformation under the saturated condition shows different characteristics, and the foundation is less stable. Differential settlements can yield a rupture between the original foundation and the filling body, so that the joint zone needs special treatments during construction period to improve the constraint of the filling body. It is suggested here that a certain reserved height of the filling body should be determined by the end of the filling process, and then measures must be taken to avoid the post-construction cracking owing to large differential settlement deformation.