论蒙脱石的脱水作用及其对地面沉降的影响

The dehydration of montmorillonite and its effect on land subsidence

过去对开采地下水所引起的地面沉降,普遍采用有效应力原理进行解释。由于早期的有效应力观点是以假设土壤颗粒与孔隙水均不可压缩为前提,所以无法描述粘土矿物层间水脱水反应所造成的体积改变。因此对由地下水超采导致粘土发生脱水作用,从而产生地层次要压密并用于地面沉降的研究较少。蒙脱石作为第四纪土壤地层中粘土矿物的主要成分,虽然颗粒细小,但其具有特殊的形态和结构特征、特殊的物理化学性质,在其成岩转变的过程中,记录了地面沉降整个过程的演变信息。蒙脱石在地层压实过程中所发生的脱水作用,造成层间水释出,需纳入到地面沉降量的计算范围之内。本文讨论了用蒙脱石的脱水作用来计算次要地面沉降量的相关问题。

Traditionally, the mechanisms of land subsidence resulting from groundwater overpumping have been explained by effective stress. Because the early view of effective stress was based on that the soil partical and pore water could not be compressed,the volume changes caused by clay minerals interlayer dehydration couldn't be explored. Therefore, the mechanism of secondary compression, also resulting in land subsidence, due to clay minerals interlayer water release resulting from groundwater overpumping, is seldom recounted in these studies. Montmorillonite, a major clayey mineral in the Quaternaty soil, with fine partical, special shapes and structure characteristics ,and especial physical and chemical properties, had recorded the evolution information of the whole process of land subsidence in the diagenetic transformation process. In the compression process,it is necessary that the released interlayer water of montmorillonite resulting from dehydration should be added to the calculation of land subsidence amount. This paper ponders further over some problems about the calculation of secondary land subsidence amount by dehydration of montmorillonite.