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Spectech's multi-purpose drill rigs offer the versatility of being able to perform both cable percussion drilling, automatic SPT and Diamond Core (“Core”) drilling and can be switched interchangeably mid-way through a hole with little effort or down-time.
This provides clients with the advantage of drilling both percussion drilling and Core drilling to complete the hole, avoiding the need to have two types of rigs on site. Having the ability to perform both percussion and Core drilling saves the client standby charges, preparation charges and mobilization charges that would normally be associated with switching rigs, effectively reducing the actual cost per metre associated with a drill program.
SES drilling believe that an efficient and effective Geotechnical study is an integral component of any proposed mine and construction project. The Geotechnical investigation is often a phased study. The first phase should identify the main issues and opportunities and define the follow-up site work. A phased approach ensures that the work is carried out efficiently and economically and allows the engineer to review the options and redefine the objectives of the investigations as required.
Spectech provides Cable percussion drilling, Diamond Core (Core), Grade control (GC), Geo-technical investigation (GT), Piezometer installation and Water bore (WB), drilling services to major, intermediate and junior mining and construction companies.
Spectech provides a broad selection of diverse drilling services (both exploration, construction and delineation) to meet the specific needs of its clients. By offering surface drilling as well as specialized and more routine drilling services, Spectech has established itself as a “one-stop shop” for drilling services, which it believes is a strong selling feature.
In providing this diverse range of drilling services in Geotechnical and Construction industry, Spectech is able to leverage its performance in one aspect of the drilling cycle to position itself favorably for other projects for the client.
Core drilling is a system that drills and collects a core (cylindrical) sample in the state it is found, i.e. in-situ. The system known as 'wireline coring' is used, ie a diamond impregnated (hollow) core bit is used which cuts until the core barrel is full. Drilling Mud / Cutting oil cools / Lubricates bit and acts as medium for lifting cuttings to surface.
Spectech provides Core Drilling in the following sizes:
Cable percussion drilling (shell and auger) is the most common drilling method used for Geotechnical site or ground investigations in the world. Depending upon access limitations and favourable ground conditions boreholes up to 60m depth can be formed.
The borehole is formed using a 'clay cutter' for cohesive soils or a 'shell' (or bailer) for non-cohesive materials. A chiselling tool can be used to penetrate very hard ground or obstructions. The sides of the borehole are supported using steel casing which is lowered into the ground as the boring proceeds. If the exploratory hole is formed in sands or gravels, particularly within the saturated zone below the water table, the steel casing will be driven into position to support the borehole sides to allow in-situ testing to be carried out and the soil to be recovered using the shell.
The material sampled from the borehole is generally sufficiently representative to determine the depth and description of the geological strata. Disturbed samples may be collected from both the clay cutter and the shell. Undisturbed samples may be recovered from any cohesive strata or from weak chalk by driving a hollow tube (100mm open tube sampler) into the ground and withdrawing the resultant core for examination and laboratory analysis. Thin-walled piston samples are sometimes used for recovering undisturbed samples of soft normally consolidated soils.
The standard penetration test, commonly known as the 'SPT', was developed to provide Geotechnical Engineering properties for foundation design purposes. The test is carried out within a borehole and the results can be used to determine relative density, bearing capacity, settlement of granular soil and to correlate the approximate strength of cohesive soil.
Dynamic probing involves driving a steel cone vertically into the ground using a sliding hammer and recording the number of blows for each 100mm of penetration. The results obtained from the dynamic probe tests can be correlated to the standard penetration test (SPT).
The test was designed to provide a rapid and economic method of assessing the penetration resistance of the ground and can be roughly equated to equivalent SPT 'N' values. The test provides a continuous profile of ground resistance with depth, rather than at the discrete depths of a conventional SPT test. The cone diameter and angle will depend upon the chosen method. For example, the super heavy dynamic probe (DPSH) has a cone diameter of approximately 50mm and a cone angle of 90 degrees.
Trial pits are carried out in order to recover large bulk samples of soil or if detailed visual examination of the strata is required. The main advantage of this method compared with light-cable percussion drilling or window sampling is the relative speed with which the work can be carried out. The disadvantage is the level of surface disturbance and the difficulty in carrying out effective reinstatement of the excavations.
