黄土结构性对其压缩-回弹变形特性的影响

Influence of Characteristics of Loess Structure on Loess Compression Rebound Deformation

工程中的地基沉降、基坑回弹等均与其压缩-回弹特性直接相关。原状黄土具有特殊的结构性,为揭示黄土结构性对其压缩回弹特性的影响,以西安某地两个不同深度Q_(3)黄土为研究对象,开展原状黄土、重塑黄土及原状饱和黄土压缩-回弹特性试验,得到原状黄土的压缩-回弹-再压缩-再回弹曲线,通过分析黄土压缩回弹过程中结构性指标的变化规律,揭示黄土结构性对压缩、回弹系数的影响规律。结果表明:当荷载不超过前期所受最大荷载时,压缩系数随结构性指标的增大而减小,超过后随结构性指标的增大而增大。直到荷载达到结构屈服应力时,黄土压缩-回弹的结构性指标最大,压缩系数同时达到极大值,随后两者均减小。回弹系数随结构性指标的减小而增大,且不同黄土回弹系数与结构性指标的关系近乎相同,说明黄土压缩、回弹系数均受其结构性的控制。

The undisturbed loess has special structural.In engineering,foundation settlement and foundation pit re-bound are directly related to its compression-rebound characteristics.To reveal the influence of the loess structure on its compression rebound characteristics,taking two different depths of Q_(3) loess in an area of Xi'an as the research ob-ject,experiments were conducted on the compression-rebound characteristics of undisturbed,remolded and saturated undisturbed loess.The compression-rebound-recompression-rebound curves of undisturbed loess were obtained.The variation law of structural indexes in the process of compression-rebound of loess was analyzed,and the influence of lo-ess structure on compression and rebound coefficients was revealed.The results indicate that when the load does not exceed the maximum load in the early stage,the compression coefficient decreases with an increase in structural index,and increases with the increase of structural index after exceeding.When the load reaches the structural yield stress,the structural indicators for the loess compression-rebound process are at their maximum,and the compression coeffi-cient also reaches its peak,followed by a decrease in both.The rebound coefficient increases with the decrease of the structural index,and different loess exhibit a similar relationship between the rebound coefficients and structural inde-xes,indicating that the compression and rebound coefficient of loess are controlled by its structure.