LAX86FA282

The plt performed 1 normal touch & go operation, & touched down normally on the second planed touch & go which was to terminate with a right dep out of the pattern. After touchdown, witnesses observed the acft roll straight along the rwy centerline for about 800 ft then begin a gradual divergence from the rwy which seemed to stabilize at about a 30 degree angle. After departing the rwy edge, the acft rolled at a constant rate of speed for an additional 900 ft through the dirt area between the rwy & adjacent taxiway before colliding with a concrete drainage abutment. The witnesses saw the wings of the acft rock back & fourth during the gnd roll through the dirt. Examination of the acft tracks confirmed that the acft did oscillate about the roll axis & shift weight from side ot side during the gnd roll. The plt had accrued only 8 dual hours to the first unsupervised solo. The accident flight was the second solo flight without supervision. No preimpact failures or malfunctions were found.