CORRELATIONS AMONGST STRENGTH PARAMETERS OF SOIL REINFORCED WITH GEOTEXTILE

Abstract

The prime objective of a pavement desiyn is to determine the thickness of different layers so that the pavenient structure can bear the load without any distress. Different parameters are used in the various desiyn methods. As it is not always possible to conduct all the tests in laboratory or field to determine, specific parameter, correlations are used to evaluate the unknown parameter provided others are known. Enouyh research work ilas rem done in all parts of the wo-rld to develop such correlations for soils. Use of reinforced soils is quite a common practice in a country like India where laryc area is covered by black cotton and other weak soils. Amony the latest developments in Civil Enyineeriny, use of geotextile is the most significant. Its use in pavements has started since last twenty five years. Studies have been conducted to see the effect of geotextile reinforcement on various strength parameters of soil and other pavement materials. But no attempt has been made to correlate these parameters of soil reinforced with yeotextile. In the present study, various laboratory tests like CBR, triaxial, plate load were conducted on unreinforced and reinforced subyrade soil (Dhanauri clay) to yet various parameters like CBR, modulus of elasticity (E) and modulus of subyrade reaction (K). All these testswere conducted for various conditions of reinforcement and confinement. CBR values were determined for both soaked and unsoaked conditions of soil and by varying the mould-plunyer ratio to see the effect of lateral confinement. For conducting the plate load tests, a pit of size 1.2m long x 1.2m wide and 1.2m deep was prepared at O.M.C. and M.D.D. in Pavement Testing Hall of Transpoqation Engineeriny Laboratory. The study shows that C.B.R. value of reinforced soil is affected by mould-plunger diameter (D/d) ratio and decreases with increase in D/d ratio. Rate of decrease however, depends on position of yeotextile in the sample. There exists a yood correlation between soaked and unsoaked C.B.R. Relationship between E and CBR is found as linear for (iv) various position of yeotextile reinforcement. E-CBR relations have been developed for different positions of reinforcement. Relationship between CBR and modulus of subyrade reaction was found exponential. D/d ratio in CBR test and confinement has also }been correlated. It is recommended that further correlations should be developed usiny other types of soils and yeotextiles before yeneralisiny the above results.