Study On The Western Mountain Area Of Zhejiang Expressway Concealed Karst Subgrade Treatment And Evaluation Method

Karst， general terms in the international for Karst， usually translated as Karst isoriginally the Balkan peninsula northwest of a limestone plateau name， where the karst isvery extensive， and later in the plateau will be named the special geological. Early in the endof the nineteenth Century， a foreign scholars have interpreted it as "the cave of karst water ora special geological effect and the result"， this explanation is recognized in the international，and continues to use until now.With the further development of China’s expressway， the stability and reliability ofsubgrade and foundation has become an important factor restricting the traffic infrastructureconstruction， to the corresponding construction has caused great inconvenience， and evencause economic loss or engineering safety accident of great. Zhejiang province highwayconstruction in mountainous area of Western Zhejiang Province during， will inevitably faceand goaf karst foundation treatment problems. Construction in Karst and mined out area to thehighway road foundation brings great hidden danger， so the treatment and its quality controlin Karst and mined out area road foundation often become the key to the success or failure ofhighway construction， the urgent need to solve the key technology of karst and mined outarea of road foundation treatment.Zhejiang carbonate rocks in northwest area of widespread distribution， most of karstdevelopment in bare and covered karst area， and at different times of the formation of karstmorphology exhibits different characteristics. Yan Rong bare zone of surface morphologywith corrosion grooves， Yan Rong swales， sinkholes， stone forest； bedrock surfacemorphological cover type Yan Rong region is more complex， the bedrock surface heighthigher ups and downs， solution groove， stone bud， sinkholes Yan Rong phenomenon ismore development， formed the Yan Rong system and surface morphology of perplexing YanRong. Carboniferous and Permian in pure limestone， karst morphological diversity， karstcaves are well developed， there are underground river distribution； Cambrian Ordovicianlimestone， the lithology of argillaceous limestone， dolomitic limestone and calcareousmudstone banded limestone karst dissolution mainly to ditch， solution groove， dissolutionfissure， solution hole and small caves mainly， I see large caves. In the area of karst development direction is mainly controlled by the Neocathaysian trunk fracture and itssupporting torsion fracture surface and east-west fault matching the rifting and the low ordertranstensional fault.Karst roadbed treatment is rare in Zhejiang province highway construction， but also thelack of relevant techniques and evaluation index of industry standards. This paper will takethe highway in a mountainous area of Western Zhejiang as engineering background， usingvarious means and methods， research from the karst prospecting exploration， karstdistribution， treatment methods of Karst Subgrade karst injection treatment selection andevaluation， all has the important significance to guarantee the construction safety， economyand rationality etc..According to the western Zhejiang Mountainous Highway Subgrade in karst topographyfeatures， geotechnical property， meteorological and hydrological and geological conditionsand geological structures， the engineering geological conditions of the sections wereevaluated. And on the basis of further analysis of the rock formation mechanism andunderground caverns soluble formation conditions and distribution process.In Zhejiang mountainous highway K242+290~K242+350， K242+870~K243+100，K243+615~243+800， K245+662~K245+847section of subgrade cave as an engineeringexample， analysis of the general principles of karst and mined out area subgrade treatmentand the common treatment methods. It analyses the karst grouting treatment， dynamiccompaction treatment and bridge across the economic indicator and the disposal effect ofthree kinds of karst treatment method etc.. And according to the multilayer evaluation modelto optimize the karst treatment programs， and ultimately determine the research section ofKarst Subgrade Treatment optimal solution for bridges crossing.On the basis of the above research， further explore the three kinds of solution treatmenteffect evaluation， summed up the sections of the treatment experience， methods andstandards through sampling drilling comprehensive evaluation，core and geophysical confirmeach other to investigate the evaluation of karst roadbed treatment effect.