Study On Performance Of High Performance Solidified Soil Roadbed

Red sandstone weathered soil,difficult to meet the requirements of high-grade highway roadbed filling,is widely distributed in Southwest China,which has the characteristics of low cohesion and easy to disintegrate in water.In this paper the solidified agent A-1 is used to improve the red sandstone weathered soil to study the road performance of the improved red sandstone weathered soil in the application of roadbed.The purpose is to provide a scientific basis for the popularization and application of the soil stabilizer improvent of the red sandstone weathered soil,so that the waste earthwork can be effectively utilized,and the use of traditional road materials in the subgrade filler can be reduced,so as to reduce the impact of over exploitation of stone on the ecological environment.The main research contents and results are as follows:(1)The maximum dry density,optimum moisture content,particle size analysis,plasticity index and CBR value of red sandstone weathered soil were studied through laboratory tests.Then compaction test and CBR test were carried out by adding solidifying agent A-1 and W-0.2.According to engineering practice and economic efficiency,the mixture ratio of 3%solidifying agent A-1 was determined to improve red sandstone.The microstructure of soil before and after improvement was analyzed by scanning electron microscope.(2)The road performance and delay time of solidified soil with different dosage of curing agent A-1 were studied.The factors influencing CBR value,unconfined compressive strength and water stability of solidified soil were analyzed.The relationships between age,dosage of curing agent and unconfined compressive strength were established.The results show that the CBR value of solidified soil increases rapidly with the increase of the content of A-1,and the CBR value increases nonlinearly with the content of A-1.The unconfined compressive strength has a good logarithmic function relationship with age and a good linear function relationship with curing agent content.The water stability coefficient of solidified soil increases with the increase of the content of curing agent.With the increase of curing agent content,the shorter the setting time of solidified soil,the faster the strength of solidified soil decreases.By comparing the CBR value and delay time of solidified soil and cement soil,it is concluded that the CBR value and delay time of solidified soil are better than cement soil under the same dosage.(3)The influence of confining pressure,moisture content,compactness and the amount of curing agent on the dynamic modulus of resilience of solidified soil is studied by the dynamic triaxial test in the laboratory.The results show that the dynamic modulus of resilience increases linearly with the increase of confining pressure.The dynamic modulus of resilience of solidified soil is greatly affected by water content,and the dynamic modulus of resilience of solidified soil reaches the maximum at the best moisture content.When the amount of hardener is 2%-3%,the growth rate of dynamic modulus of resilience of solidified soil is less than that of 3%-5%,and the increase of the amount of curing agent plays a certain role in promoting the growth rate of the modulus of resilience.(4)The construction technology of solidified soil was used to pave the test section in Chengdu.The deflection and dynamic resilient modulus of the test section at different curing time were detected by PFWD.The results show that the dynamic modulus of resilience after 1 day and 7 days of curing is 1.67,3.29 and 4.07 times higher than that before.The relationship between dynamic modulus M_R of indoor test and dynamic modulus E_p of field test is established,E_P=13.66M_R-1534.44.