Rd-unit penetration resistance of probe;
E- penetration per stroke;
M is the mass of the hammer;
H the falling distance of the heavy hammer;
G—— acceleration of gravity;
A- probe cross-sectional area. When the penetration resistance Rd is used to determine the bearing capacity of foundation, it is usually estimated by dividing by a coefficient.
Part of the hammering energy (the product of the weight of heavy hammer and the falling distance) in dynamic penetration test is used to overcome the penetration resistance of soil to the probe, which is called effective energy; The other part is consumed by the collision between the hammer and the sound probe.
The elastic deformation of the probe can overcome the friction between the probe and the soil of the hole wall, and the energy consumed by the plastic deformation of the foundation soil when the penetrometer pierces the human body, and the energy consumed by the elastic deformation of the soil when it pierces. Assuming that the hammering efficiency is η, the effective hammering energy can be expressed as ηMgH.
Extended data:
Dynamic penetration test is a commonly used in-situ test method in geotechnical engineering investigation, and its results are widely used. In view of many factors affecting this method, especially the inconsistent range and method of pole length correction in various industries, nonstandard test operation, improper soil layer division and unreasonable determination of soil layer density.
Then there is the problem of evaluating the conclusion of the project site and the inappropriateness of the determined geotechnical engineering design parameters. It is very necessary for geotechnical engineering to unify the scope and methods of pole length correction as soon as possible, and formulate unified regulations for pole length correction, and take them as national guiding laws and regulations.
Baidu Encyclopedia-Dynamic Penetration Test