بعض التأثيرات السلبية لمياه الصرف الصحي على التربة الطينية

الملخص EN

This study deals with the effect of wastewater on some physical, chemical and consolidation properties of clayey soil and investigates the effect of wastewater flow beneath buildings’ and structures’ foundations due to; breaking of wastewater pipes, the permeation of sewage water in to the soil, or its flow on the land that hasn’t been constructed yet.

Soil samples have been taken from the University of Technology site at a depth (1– 1.5) m and the preparation of samples were in two manners: the first by taking undisturbed samples which have been flooded with wastewater that allowed to permeation and flow through soil sample, the second, by taking disturbed samples saturated with wastewater to ferment.

The soil that used in this study was silty clay with low plasticity (CL-ML) and the result of this study which lasted for (10) months showed an increase in the chlorides and sulphates ions during the first months and then decreased, it has been noticed an increase in the concentration of carbonates ions along the period of study and an increase in organic matter due to wastewater nature.

The results of soil-wastewater interaction showed an increase in liquid limit, plastic limit and plasticity index for both undisturbed and disturbed samples and the specific gravity of soil decreased due to wastewater chemical contents.

The void ratio has been increased and preconsolidation pressure decreased which may be attributed to the dissolution of soluble salts and the influence of carbonate bonding that may be broken when subjected to load.

Also, the results showed an increment in the ability of soil to be compressed when soil compression index (Cc) increased and soil swelling index (Cr) increased, too.