Study On Engineering Properties Of Phyllite And Waterproof And Drainage Technology Of Its Roadbed

The highway from Ankang to Pingli is located in the middle and low mountainous region of southern Qinling Mountains,where terrain conditions are relatively complex and the vally is broad.The project areas belong to subtropical moist climate zones,and its overall natural geographical features are as follows:warm climate,abundant rainfall,lush vegetation,good ecological environment.Lithology is mainly of the Silurian(S) colored sericite phyllite.There are also peaty slate,various schist and limestone.In this area phyllite are widely distributed.Because a lot of phyllite is discarded in the cutting and tunnel excavation process,and other local better subgrade filling is relative deficient in the engineering construction,if a large number of abandoned slag is used for highway subgrade filling,we can not only reduce the amount of abandoned residue,protect the ecological environment,but also reduce the cost of the project,which has a very positive economic,social and ecological benefits.However,the phyllite is not only of low mechanical strength resistance,but also the water-stability is poor and easy to be softened.So,it needs to be further studied whether phyllite could be used as the construction of the highway roadbed.This paper has been written through a combination method of laboratory test and field test,which is a comprehensive study that includes the engineering properties of phyllite and the waterproof and drainage measures of its subgrade.Original rock mineral composition,physical indexes such as natural moisture content,density,strength are tested and filler particles,liquid plastic limit,heavy compaction and CBR are analyzed.The results show that the phyllite’s natural moisture content and material plasticity index is low;its density is relative high;it has poor strength and stability and water has a big influence on it.The typical sample test indicates that packing CBR value is more than 3%,which can meet the requirements of the embankent filling.The hydrological characteristics of phyllite, such as softening, disintegration, swelling and permeability are tested, and results showed that:prolonged softening of phyllite ispoor;water disintegration is not sensitive;expansion and permeability are both small.After a analysis of the water influence on phyllite roadbed,put forward a few waterproof and drainage technology measures to improve the subgrade stability.Aimed at An-ping project,a reasonable and feasible phyllite’s structure combination is put forward and after a real engineering application and field test,the results are analyzed.Construction technology scheme and process,waterproof and drainage measures during construction,and construction quality control have been put forward,and these research results have a very strong application and popularization value.