This paper describes the study of the permeable grouting method as a liquefaction countermeasure using actual execution data and laboratory test data. Following results are obtained.
(1) The shear modulus at a small strain of soils improved with permeable grouts is as same as that of unimproved ones.
(2) The modulus of deformation at a large strain of the improved soils increases with the unconfined compressive strength, and the relationship between the modulus of deformation and the unconfined compressive strength is obtained as follows,
E50=40～100qu
(3) The permeable coefficient of the improved soils decreases to 1/100 to 1/1000 times the original one although the coefficient of volume compressibility does not change.
(4) The unconfined compressive strength of 100KN/m2 may be a target value for improvement as the liquefaction countermeasure. However, the target value of improvement strength shall be determined with the method using cyclic triaxial test result.
(5) The strength of soils improved in site decreases with distance from the injection point of the grout.