The free fall of the hammer is controlled and set by the operator via the steel sheet piles hammer operation and control equipment. If the word readings are displayed, diesel hammers are often difficult to do. Although there may be corresponding control equipment, the hydraulic hammer distance can be calculated by the number of squares, and then refer to the graph provided by the manufacturer to use different control equipment, but usually the energy is estimated.
Recording hammering speeds is also necessary for double-acting hammers, but the best way to date is to install a digital reader or to connect to a portable laptop to store and monitor piling records.
The sensor can be mounted on steel sheet piles by means of dynamic monitoring, and the following data are measured with a piling analyzer (PDA): hammering efficiency, steel sheet piling stress and pile bearing capacity. The number of hits and hammers can be measured using a Saximeter or similar device. The measured data can be analyzed in software. For example, the CAPWAPX curve fitting software can be used to determine soil parameters for the site.
Impact hammer selection study shows that the existing hammer in the normal hammering speed of 5m / s, each hammer in its best performance to overcome the piling resistance of about 1000kN, on the basis of the pile hammer operating efficiency 80% to 95% When approaching the standard penetration rate, the relationship between the required energy and the piling resistance can be found, and the line indicates the acceptable boundary between piling performance and effective stopping criteria (defined here as Each 10 hit 25mm penetration); selected pile hammer should not exceed this line.
The total resistance can be estimated according to the following formula: R-pile into the soil within the scope of the internal resistance and F sheet pile dynamic resistance coefficient, and the impact speed, damping effect and lock mouth friction related to the selection of steel sheet pile hammer, Into the speed of less than every 10 hit 25m, so the pile end resistance can be ignored, only in the pile can not fight it, the pile end resistance was gradually apparent. Surface friction: pile contact area of soil X unit friction. The damping effect per meter of the Larsen steel sheet piles and the frictional resistance of the lock are also related to the soil properties and the depth of the buried soil.