EARTH PRESSURE, DEFORMATION AND CONCRETE STRAIN MEASUREMENTS ON AN ABUTMENT OF THE RAHMEDE VALLEY CROSSING NEAR LUEDENSCHEID

ERDDRUCK-, VERFORMUNGS- UND BETONDEHNUNGSMESSUNGEN AN EINEM BRUECKENWIDERLAGER (RAHMEDE-TALBRUECKE BEI LUEDENSCHEID)

THE CONSTRUCTION OF THE SAUERLANDLINIE MOTORWAY REQUIRES BRIDGE STRUCTURES ABLE TO BE FOUNDED ON ROCK. THIS RAISES THE QUESTION OF WHETHER THE WINGS OF THE ABUTMENTS WOULD REMAIN ABSOLUTELY STABLE ON THE SUBGRADE SO THAT THEIR DESIGN COULD BE BASED ON THE PARAMETER OF LATERAL EARTH PRESSURE AT REST OR WHETHER WALL MOVEMENTS, CAUSED BY SETTLEMENTS AND DEAD-LOAD DEFORMATIONS OF THE WALL WOULD OCCUR WHICH WOULD BE SUFFICIENT TO PRODUCE A PRESSURE CONSISTENT WITH COULOMB'S THEORY. IT WAS THE OBJECTIVE OF THE RESEARCH PROJECT TO CLARIFY THIS QUESTION TO MAKE IT POSSIBLE TO DESIGN SIMILAR STRUCTURES MORE ECONOMICALLY. THE WINGS OF THE ABUTMENTS ARE DESIGNED AS ANGULAR RETAINING WALLS WITHOUT STIFFENING RIBS. THE RESEARCH WORK WAS CARRIED OUT BY MEANS OF EARTH PRESSURE METERS, RESISTANCE THERMOMETERS, STRAIN GAUGES, INCLINOMETERS AND HIGH PRECISION LEVELLING INSTRUMENTS. THE EVALUATION OF THE MEASUREMENTS DO NOT ALLOW UNIVERSAL CONCLUSIONS TO BE DRAWN AS TO THE DESIGN OF HIGH RETAINING STRUCTURES. WITH ROCK OF INADEQUATE STABILITY, AS WAS THE CASE WITH THE SUBGRADE UNDER CONSIDERATION, THE SUBGRADE AND RETAINING WALL DEFORMABILITY, WHICH WAS DESIGNED ON THE BASIS OF CONDITION I, IS NOT SUFFICIENT TO REDUCE THE EARTH PRESSURE AT REST TO THE EARTH PRESSURE CONSISTENT WITH COULOMB'S THEORY. IN SUCH A CASE, THE CALCULATION SHOULD ALWAYS BE BASED ON AN EARTH PRESSURE VALUE WHICH IS LARGER THAN THE LIMIT MENTIONED. THE EXTENT TO WHICH THE EARTH PRESSURE VALUE SHOULD BE INCREASED DEPENDS ON THE STABILITY OF THE ROCK, ITS MORPHOLOGY AND DEFORMATION PROPERTIES. IF THE DEFORMABILITY OF ROCKY SUBGRADE IS NOT KNOWN IT IS RECOMMENDED THAT HIGH RETAINING WALLS BE CALCULATED AS IN RETAINING WALLS ON STABLE ROCK, THE CALCULATION BEING BASED ON THE COEFFICIENT OF EARTH PRESSURE AT REST LAMDA = 1 - SIN PHI ACCORDING TO JAKY (SEE FINAL BAST REPORT DATED JANUARY 1970).