由於黏土的滲透係較低，黏土層加載後完成壓密所需時間較為費時，為能加速黏土層的壓密速率，有相當多之工程方法可符合需求，也兼具實務成效。近來由於電腦軟體應用程式非常普及，數值運算方法分析已成為設計的參考依據，本研究針對黏土層加速壓密利用路堤填築施工之預壓及打設砂樁為案例，利用有限元素PLAXIS程式進行分析，並探討相關之力學行為，由分析成果得知：（1）預壓工法及打設排水砂樁均有加速黏土層壓密之成效，尤其排水砂樁之施設，其功效更為顯著；（2）鄰近填築區域下方之黏土層，其水壓力之改變，較具實質性之壓密指標，至於遠離填築區域如趾部下方之黏土層，其水壓力之改變情形，似乎與壓密成效，較不具關連性；（3）排水砂樁之施設或填築預壓，配合水壓力之改變情勢分析，呈現適足之壓密資訊，可提供工程界作為評估沉陷量與完成時間之設計參考。 Much more time is ususally required in complete consolidation of clay layer after sustaining the load due to its low permeability. For accelerating complete consolidation in clay layer, many construction methods are developed for meeting the engineering requirement and having the efficiency of practice. In recent years, the computer software programs are used widely and numerically computational analysis becomes the reference of design. This study will aim at the related mechanical behavior of accelerating complete consolidation in clay layer using the cases of preloading in embankment and installing sand drain in clay layer. All analyses are performed with PLAXIS program. From the analyzed results, it indicated that (1). The methods of preloading in embankment and installing sand drain in clay layer are both effecitive in accelerating complete consolidation in clay layer. The latter is more significant; (2).The pore pressure change near the portion of fill plays a practical index in the evaluation of efficiency of consolidation. The pore pressure change far away from the portion of fill is not associated with consolidation efficiency; (3).The appropriate consolidation information incoportaed with the analysis of pore pressure change from preloading in embankment and installing sand drain in clay layer can provide the design reference of evaluating the settlement and completed time of clay layer in engineering circles.