Snow strength penetrometer

摘要

The snow penetrometer apparatus with data acquisition hardware measure force required to push a small dimension tip member into a snow surface at constant speed that: i) is less than 5 mm in diameter or cross-sectional width, ii) has up to a 90 DEG included angle; iii) has a flared tip and iv) is extended beyond a penetrating head. The penetrometer tip member has a high elastic modulus and is attached through a connecting rod to a stiff penetrating head that is in turn attached to a driving rod. The penetrometer tip member acts through a force sensing transducer. The driving rods are a meter in sectional length that can be joined together for snow penetration up to several meters. The depth of snow penetration is determined by measuring movement of a drive motor or drive rods. The penetrometer tip member is driven downward by a constant speed rotary or linear motor. Two different penetrating head designs are used. The first penetrating head design has a diameter slightly larger than the driving rod to reduce sidewall friction. The second penetrating head design has the same diameter as the driving rod to reduce the volume of influence ahead of the penetrating head. Both heads are low included angle of 30 DEG or less. A measured event of the penetrometer tip encountered force is recorded and correlated with depth of penetration for later analysis to determine its mean value and variation about this mean value to obtain an index measure of inter-grain bonding and snow grain size.