The Research On Alkali-Activated Composite Grouting Material For Reinforcing Loess Foundation

In the western part of China,there is a large area of loess.After the collapsing of the loess foundation,the buildings and infrastructure in the upper part of the foundation are prone to various diseases and need to be treated.As an important branch of static pressure grouting,with the development of science and technology,split grouting has been used in the consolidation of collapsible loess foundations in recent years.However,the scientific selection of grouting materials,which is suitable for the split grouting project of the collapsible loess foundation in the western region,and the problem of judging the slurry diffusion law of the grouting material and the final reinforcement effect,are still urgently needed to be solved.Ordinary cement grouting slurry has many characteristics such as high cost,low condensation and high water-discharging rate.So,it can not meet the requirements of eliminating collapsibility and improving foundation bearing capacity when grouting loess foundation.Therefore,this paper proposes an alkali-excited composite grouting slurry which is suitable for splitting grouting in loess area,and studies the properties of alkali-excited composite grouting material from macroscopic and microscopic perspectives through material pro perties test;the simulation test method compares the diffusion law and reinforcement effect of alkali-excited composite grouting;using field test,the method of direction al and stratified split grouting using alkali-excited composite grouting material is proposed,and the reinforcement of splitting grouting was evaluated.The main research contents of this paper are as follows:(1)The properties of alkali-activated composite grouting,such as viscosity and gel time,were tested and analyzed by orthogonal test.It was found that the most important factor affecting the gel time of alkali-excited composite grouting materials is the water glass content;the most important fact or affecting the strength and resistance of the serous stone body is the water-binder ratio.Finally,the optimal mixing ratio of alkali-excited composite grouting materials was obtained by microscopic experimental study of slurry stone.(2)By grouting simulation test,using alkali-activated composite grouting material grouting soils with different ground parameters,and analyze the characteristics of these soils.The results show that the compaction degree of soil will have a great influence on grouting volume,slurry pressure,the average width of the serous stone bodies and the diffusion radius of the slurry,and the compaction degree of the soil is smaller,the grouting volume is larger,the grouting pressure required is smaller,the effect of grouting reinforcement is better.At the same time,study the diffusion law of the slurry in the soil with the same ground parameters under different grouting conditions.The results show that the grouting slurry always flows along the direction of the smallest stress in the grouting soil during the grouting process.The larger the slurry water-binder ratio,the easier it is to form the hydraulic splitting of the slurry to the surrounding soil.The smaller the grouting pressure required,the shorter the grouting tim e required,and the final slurry diffusion radius will be larger.(3)According to the field test of splitting grouting,by the obtained test parameters and the analysis of the diffusion law of the serous stone bodies formed in the loess,it is considered that the layered grouting can better achieve the directional splitting grouting.More dendritic veins are formed,so that the veins can better exert the skeleton effect on the soil.The alkali-excited composite slurry has good effect in the actual grouting reinforcement project in the collapsible loess area,and can achieve the reinforcement effect on the soil.