Determination of the resistance of the cylindrical­tubular drill for trenchless laying of underground communications

Svyatoslav Kravets,Olena Chevychelova,Dmytro Klets,Vladimir Suponyev,Oleksandr Kosiak,Anatolii Nechydiuk,Oleksandr Rieznikov

doi:10.15587/1729-4061.2018.131838

Abstract

The determination of the total resistance to penetration of the annular drill into the soil is based on the concept of changing the elastic state of the soil during its compaction, which is defined by the compression modulus of soil deformation. This parameter comprises all the physical and mechanical properties of each type of soil and makes it possible to specify the laws of the normal pressure of penetration resistance acting on the surface of the conical and cylindrical parts of the working body. The proposed theoretical models of processes occurring during penetration of the annular drill into the soil give s an opportunity to determine the influence of the parameters on the resistance force for each working procedure, depending on the physical and mechanical properties of the soil. It has been found that the maximum length of the annular drill is determined for the conditions of soil movement (unplugged condition), which, for example, with a cylinder diameter of 28 mm, is 0.87 m, 1.04 m and 1.16 m respectively for sandy clay, semi-solid loam and tough clay. It is now clear that a 2-fold increase in the internal diameter leads to an increase in the core length of 1.75 times. It has been determined that the two-cone drill does not facilitate passage of soil through itself and it causes soil plugging as well as formation of soil plugs on the frontal planes, which leads to an increase in drag force. Therefore, to provide unplugged conditions during pipe jacking, the drill with a single external cone should be used. The obtained results of the work can be used to substantiate the rational parameters of the working equipment for creating a horizontal borehole in different types of soils.

Highlights

One of the methods of trenchless laying of underground communications is pipe jacking or shield tunnelling method
The problem is the compression deformation modulus of the soil; g is the of determining the resistance to penetration of the cylin- ratio of the inner and outer diameters of the annular drill, drical-tubular drill for trenchless laying of underground communications requires further research
The proposed theoretical dependences for determining the forces resisting the penetration of the annular drill of the equipment for trenchless laying of underground communications are based on the physics of the process of interaction between the drill and the soil and give an opportunity to obtain objective calculations of design parameters of the working equipment as well as to determine power characteristics of installations for the formation of boreholes by the pipe jacking method

Summary

Introduction

One of the methods of trenchless laying of underground communications is pipe jacking or shield tunnelling method. It is employed for constructing tunnels of relatively large diameters from 300 mm to 800 mm and larger ones. In this case, a borehole is usually formed by a steel pipe, which serves as a protective casing. To reduce soil cutting resistance and to adjust movement direction, the end of the pipe is equipped with a pointed annular drill. This process requires a lot of effort.

The aim and objectives of the study

Determination of the resistance of the cylindrical-tubular drill

Findings

Conclusions