【Sany construction method】A brief analysis of the causes of the eccentricity of the rotary drilling rig

With the rapid development of the piling foundation industry, rotary drilling drills occupy most of the market share by virtue of environmentally friendly, convenient and efficient construction technology, but under complex construction conditions, rotary drilling rigs inevitably have some shortcomings, and oblique holes are one of them. According to the engineering specifications, the verticality of the borehole should be controlled within 1%, and the verticality requirements of individual sites will even reach 5‰.

Oblique hole not only has a bad impact on the quality of the project, but also causes huge economic losses and psychological impact to the construction party, especially in the process of sweeping and correcting the deviation, it is more likely to cause a large secondary accident, including: serious over-square, collapsed hole buried drilling, so as to the constructionRotary drilling rigsCause the drill pipe key bar to break, power head oil leakage, wear and other equipment failures. How to effectively prevent the occurrence of borehole deflection accident is an important task in the construction process of rotary drilling rig.

The uneven distribution of the mechanical strength of the formation is very easy to induce inclined holes. It is found that oblique hole accidents are easy to occur in inclined rock formations, limestone karst cave formations, solitary boulder formations, hard rock formations, alternating soft and hard strata and pebble strata.

Due to equipment, debugging or operator operation, the mast automatic sag function of individual rotary drilling rigs cannot ensure the verticality of the mast, and the mast will have a slight deviation. During the construction process, the uneven settlement of the chassis caused by the vibration of the rotary drilling rig and the pressure relief of the cylinder will also cause the original vertical mast to deviate. The mast deflection can be detected by borrowing a theodolite or total station from the construction party, and using the instrument.

The hole deviation phenomenon in the construction process of rotary drilling rig is not simply caused by the objectivity of equipment and geology, or by the subjectivity of operation, or some other factor, and the causes of the problem must be considered from multiple angles and aspects. To deal with any construction method problems in the construction of rotary drilling rigs, it is necessary to consider and reconcile the relationship between equipment, geology and operation in the construction.