Experimental Research On Mechanical Properties Of Loess Improved By Solidified Agents

Loess is mainly distributed in north and northwest of China. Many difficulties are caused by disintegration and collapse of loess with water to embankments, channels and slopes of local loess projects, such as land subsidence, landslide, ground crack and other geological disasters. Hence, some proper measures should be taken in order to improve the strength and stability of engineering buildings.Chemical improvement of loess is an important topic in the areas of loess foundation treatment. The study on improvement of loess has a good future in the areas of loess engineering. Experimental research on the improvement of loess could solve the potential hazards of loess and improve loess foundation engineering. Besides, it has important applied value and theoretical basis.In order to discuss the different effects of solidified agents on mechanical properties of loess, a series of experiments are conducted to analyze the mechanical properties and permeability of the raw loess in Taiyuan before and after treated by varying contents of cement, lime and SH. The mechanical properties and permeability of loess improved by solidified agents are taken by a series of tests including compressive strength, direct shear, frost resisting, water stability, wet-dry and permeability. The orthogonal experiment of SH and cement, lime and SH compound material were carried out to find the main factors which affect the strength of combination ratio. It will provide useful test basis and theoretical reference to foundation treating measures of loess areas. The results of the experiments show that:(1) Mechanical properties of the loess can be improved by cement, lime and SH. With the increasing of dosage of cement, lime, SH, age and dry density, the mechanical properties of loess are improved. But compressive strength of loess improved by lime do not always increase as the dosage.The mechanical properties of loess improved by SH is better than by cement and lime.(2) Orthogonal experiment of cement, lime and SH combination shows that the main factors that affect the compressive strength of loess improved by solidified agents vary with the combination of solidified agents. The former is SH, and the latter is curing age. Compressive strength of the loess improved by cement and SH compound material is higher than by cement and SH; Compared with the loess improved by lime, loess improved by lime and SH compound material have higher compressive strength. The shear strength of loess improved by Lime and SH compound material can be effectively improved.(3) The frost resistance of loess improved by SH is better than loess improved by cement. When the dosage of solidified agents is higher than16%, loess improved by SH can meet at least twenty-five times requirements of frost resistance; while loess-cement can only meet at least fifteen times requirements of frost resistance.(4) Water stability coefficient of loess improved by SH basically maintains about0.9, which has good water stability. Compared loess-cement, the water stability coefficient of loess improved by cement and SH compound material is increased14.93%, and its softening coefficient increased about550%with loess improved by SH. The water stability coefficient and softening coefficient of loess improved by lime and SH compound material are respectively increased by5.32%and281.82%.(5) When the dosage of SH is higher than14%, loess improved by SH can meet at least fifteen times requirements of dry-wet circulation. (6) With the increasing of solidified agents and the longer of age, the permeability coefficient of the improved loess is smaller. Permeability of loess improved by lime is better than loess improved by SH and loess-cement. The permeability coefficient of the loess improved by solidified agents basically maintains in the same order or the down level of magnitude, which can meet the anti-seepage requirements of general engineering projects.(7) The cost performance of loess improved by SH is1.2times as much as cement, and2.1times of lime. Therefore, SH is a new promising material for loess improvement.