含砾黏土压实及强度特性的实验研究

Experimental Study of Compaction Characteristics and Strength Behavior of Gravelly Clay

摘要:

采用室内重型击实实验对含砾黏土的压实特性进行分析,结合CT断层扫描研究材料整体干密度、最优含水率及黏土的压实程度与掺砾量、含水率等因素之间的关系。根据无侧限抗压强度实验结果,比较不同掺砾量和不同含水率下的无侧限抗压强度大小。结果表明:掺砾量较低时砾粒与黏土之间就已出现粒间空隙;含水率较高时,这些空隙及黏土孔隙中的水在击实过程中难以排出,同时水还阻碍了封闭气泡的逸出,造成黏土的压实效果明显降低;随着含砾量的增加砾粒逐渐起到骨架作用,减小了作用在黏土上的击实能量,也造成黏土的压实程度差于纯黏土。含砾黏土的无侧限抗压强度主要由黏土成分的密实程度控制,因而受到砾粒含量和含水率的影响,整体上随着含砾量的增加而降低,含水率较高时的下降幅度更明显。

Abstract:

Heavy compaction tests were conducted to investigate the compaction characteristics of gravelly clay.Combining the results of a CT scan,the effects of gravel content and water content on maximum dry density,optimum water content,and clay's compaction degree were studied in detail.The undrained shear strength of gravelly clay with different gravel content and water content were also studied.It was found that there were extra voids between gravel and clay even when the gravel content was relatively low.Consequently,it was difficult for the pore water to flow throughout the soil and the air in the inter gravel voids was blocked by the water so that the dry density of the clay was significantly reduced.Simultaneously,the compaction effort applied to the clay was also reduced because of the existence of the gravel skeleton,thus the degree of compaction of the clay decreased with the increase of gravel content.The results of the compressive tests also showed that the undrained shear strength of gravelly clay depended on the gravel and water content.As the gravel content increased,the undrained shear strength decreased,especially in the case of high water content.