| Red sandstone is widely distributed in southern Zhejiang Province.Red sandstone is easily slaked and broken by external factors such as dry-wet cycle,p H value,temperature and disturbance.Directly used as roadbed filler will cause roadbed diseases,and pre-slake it into red sandstone with stable particles.The use of soil for highway roadbed filling can not only reduce a large number of abandoned materials,protect the environment,but also greatly reduce the project cost,which has significant social and economic benefits.In this paper,relying on the reconstruction and expansion project of Hangjinqu G6,the mineral composition and slaking characteristics of the red sandstone in southern Zhejiang were studied.And in the engineering test section,the relationship test between the compaction degree of red sandstone soil roadbed and compaction work per unit volume was carried out.And a real-time monitoring method for judging the compaction degree of red sandstone soil roadbed by the compaction work was established.The following conclusions are reached:(1)Through XRD test,slaking resistance test and sieving test of the red sandstone in southern Zhejiang,it is found that the red sandstone in this area contains more montmorillonite,which is easy to absorb water and slake.The particles with the largest diameter are the main ones,accounting for more than 95%,and the particle size tends to be stable.(2)The liquid limit and plastic limit of the red sandstone soil formed by disintegration are 24.1%and 12.5%respectively.Its plasticity index is 11.6,which belongs to pulverized clay.The optimum moisture content is 10.3%.Under the condition of this moisture,the triaxial shear test results in c=22.39k Pa,φ=31.95°,and the strength is high.(3)The compacted red sandstone soil still has certain slaking property,which is influenced by external factors such as dry and wet cycles,p H value,temperature and disturbance.The order of influence from strong to weak under the condition of dry-wet cycle is:disturbance>p H>temperature.The slaking of compacted red sandstone is significantly affected by disturbance.The greater the degree of disturbance,the faster the slaking.When the p H of aqueous solution is in the inert range(p H=8.0～9.0),the slaking of compacted red sandstone is weakest.When p H<8,the slaking decreases with the increase of p H value,and when p H is greater than 9,it increases with the increase of p H value.Changing the water temperature or the temperature of compacted red sandstone soil will form the temperature difference△T,The disintegrability of compacted red sandstone soil increases with the increase of|△T|.(4)Applying the intelligent compaction technology,through the on-site compaction degree monitoring test,the relationship between compaction work per unit distance and the compaction degree is established.Based on this formula,the compaction degree of red sandstone soil roadbed is monitored in real time.When the unit volume compaction power is 146.50 k J/m~3,the compaction degree of red sandstone soil roadbed reaches 95%,the CBR value of roadbed is 13.6%,and the bearing capacity meets the requirements.The red sandstone soil in southern Zhejiang Province can be used for roadbed filling. |
