Study On The Disintegration Properties And Microstructure Of Guilin Red-Clay Under The Different Environmental Conditions

In order to avoid the engineering hazards caused by the disintegration of red clay in the construction of highway in karst area,this paper studied the factors affecting the disintegration characteristics of red clay,and the mineral composition,chemical composition and microstructure of red clay has been discussed,which provided some basic theory to exert the application potential of red clay as well as to improve the safety and stability of red clay.The main conclusions were as follows:（1）Under the condition of low moisture content and low degree of compaction,the disintegration of red clay was obvious and the rate of disintegration was fast.In the process,there were a lot of bubbles,and complete disintegration almost occurs.When the water content was more than 30%and the compaction degree was more than 90%,the disintegration of red clay was not obvious and the rate of disintegration was slow,thus the complete disintegration would not occur.With the escaping bubbles,the surrounding water was clear.（2）Under the condition of water content and compaction degree,with the higher the ambient temperature,the more obvious the disintegration of red clay was appeared,and with the faster the disintegration rate.At 60°C,all the samples were disintegrated completely,accompanied by a large number of bubbles.It is also found that the effect of water content on the disintegration characteristics of the soil was more obvious than the compaction degree at the same temperature.（3）Under the conditions of water content,compaction degree and temperature,the sample was placed in different solution,in which the acid solution of PH=4.5,the alkali solution of pH=10 and the natural rain water of Guilin.Under the conditions of acid solution and rain water,the disintegration phenomenon was more obvious than the groundwater condition,and the disintegration rate was faster.Under the condition of alkaline solution,the disintegration of red clay was weaker than that of groundwater,and the rate of disintegration was slow,which could inhibit the disintegration of red clay.（4）The water quality of the rainwater in Guilin was analyzed by the XRD,XRF and scanning electron microscopy.The results showed that the content of the mineral composition of the red clay had little effect on disintegration experiment,in which kaolinite has a certain expansion,that increased the pore water content.The main chemical composition in red clay were Al₂O₃ and Fe₂O₃,that react in acid solution and rain water,the degree of consolidation decreased and the disintegration increased.On the contrary,in alkaline solution,the adsorption force of the particles and the cementation of red clay were enhanced and the disintegration was reduced.The results show that the porosity of the soil was increased and the connectivity of the pores was increased,and the micro-aerial structure was occasionally formed.The arrangement and distribution of the particles were not obvious in the micro-structure change analysis.（5）Combining the characteristics of karst highway subgrade in Guilin area and the disintegration characteristics of red clay,the measures to prevent highway engineering harm were put forward.The following measures were:1.Try to set up a good drainage channel;2.Reduce the damage of soil strength caused by human engineering activities;3.To avoid construction in the long-term rain or exposure environment.