The following specification particularly describes the nature of his invention and the manner in which it is to be performed
This invention relates to the new method of boring for the installation of Bored Cast In Situ (BCIS) piles specially through the thick layer of Blast Furnace Slag (BFS) fill which is a very difficult material to penetrate.
The projects in Iron and Steel industry involves the construction of Sinter Plant, Blast Furnace, Stock house. Raw material handling systems which consists of wagon tippler, tack hopper, junction towers, silos, etc. The project sites in the steel plant for TISCO, SAIL and for other clients, cover areas where the groomed is generally filled up with thick layers of BFS.
Basis of the invention
The applicant has the necessity of constructing foundations for the above mentioned structures for the ISSCO Bumper Project, executing a 2.5 minion ton per year capacity steel plant in the Harahan. Since the foundation has to support the heavily loaded structures pile foundations are to be provided. BCIS is the type of pile recommended by the consultant. The project site consists of dumped slag flu, which are of heterogeneous type and also with scrap steel parts of different sizes. Hence conventionally, boring through such slag fiU is being carried out by using tripod-bailer / chisel with permanent steel casing tube. In view of a lot of limitations and difficulties which result in excessive cost and time to carry out the boring by the above tripod-bailer / chisel method an alternative combination method of boring using a vibratory probe is conceptually developed which leads to the development of novel boring method to carry out the BCIS piles in strata with BFS or other hand granular soils.

Prior art
Boring through BFS and installation of BCIS piles are being conventionally achieved using tripod-bailer / chisel with permanent steel casing tube(Refer Figures-1&2). This involves cutting the slag boulders by chasseing to form the pile bore. This is a very tedious and time consuming work. Some times obstructions are met in the form of big boulders / steel scrap materials while forming the pile bore and as a resist it is often required to shift the pile point from the original location to a new location. Also, in the conventional method permanent steel casing tube is required to prevent the collapse of the surrounding slag into the pile bore. In view of these drawbacks, the progress of the piling is very slow and it is very difficult to maintain quietly of the pile by the conventional process. Moreover, due to the permanent steel casing tube, the friction that can be derived from the slag fill on the concrete pile is neglected by the designer which leads to a very uneconomical pile design and hence the high foundation cost.
So far some methods for piling have been developed with an auger driving tool attached to a Kelly bar as described below:
The US Patent No. 6079906 particularly defines a method for making pile foundation in soil with a driving device having an auger including two concentric tubes. The outer tube connected to the upper part of the auger and the inner tube connected to the lower part of the auger and both tubes are displaceable with respect to each other. The drilling device is by rotating both the tubes simultaneously in opposite directions and advancing the

auger through the soil whereby the soil is compacted against a wall of formed hole. After completing the flu depth of hole, the auger is removed and the concrete is poured in the formed hole.
The US Patent No.7093679 describes a drilling machine for bored piling with a drilling tool, which is generally an auger bit, attached to an end of keUy bar. The keUy bar is rotated with a rotary drive. The rotary drive rotates the Kelly bar with the driving tool contact with the ground so as to drill the hole. The spoil or cuttings created dieing the process of draping are carried out by the drilling fluid which is circxilated in and out of the dried hole. In some operations the spoil is simply lifted out of the hole by way of the auger bit.
The US Patent No. 4877091 covers the downcrowdable telescopic angering apparatus and drilling rig, which can drill large diameter holes to great depths with less overhead clearance.
Drawbacks of known art
The usually adopted BCIS piles are to be installed through the dumped slag fill which are of heterogeneous type and also with scrap steel parts of different sizes. This necessitated boring for the pile to be carried out using tripod-bailer / chisel. By this method the boring progress is a very slow and expensive.
Also to protect the pile bore from collapsing slag fiU, permanent steel casing tube is very much required. Providing this permanent steel casing has a major impact on the cost of the foundations. This item of steel casing tube, not only directly adding the cost of steel material to the foundation cost but also does not take the advantage of the inherent strength of the BFS. So, this will result in the need for more number of piles, which has an impact on the foundation cost and the construction time schedule.

Objects of the invention
The object of this invention is to develop an appropriate and efficient boring method for the installation of BCIS piles in soils overlain by thick layers of blast furnace slag or other hard granular soils.
The main components of the system, for the boring comprises of
1. vibratory probe hanging from a suitable crane
2. rotary driving rig.
Principles of the invention
i) Initial slag boring using the vibratory probe by penetrating the
vibratory probe to the full depth of the slag.
ii) Then the final borehole formation up to the required depth of the pile forming level is done by the rotary drilling rig.
Figures-3&4 show the sequence of forming a pile bore.
Differences / Distinguishing features between the invention and conventional method.
In the conventional method, boring through BFS is carried out using tripod-bailer / chisel. This involves cutting the slag boulders by chasseing to form the pile bore. In the invention the boring through BFS is by penetrating the vibratory probe and the borehole is formed by vibratory energy.
In the conventional method, permanent steel casing tube is required to protect the pile bore whereas in the invention, there is no need of casing tube.
In the conventioital method of ping, the pile design does not consider the strength of the slag. In the invention, since the slag fill is compacted due to the vibratory action of the vibrating probe, the friction

capacity of the slag can be considered in pile design resulting in higher load carrying capacity of a pile and consequential reduction of total number of piles to carry the external load and hence the cost of pile foundation is comparatively very less.
Some times due to obstruction to carry out the pile bore, in view of encountering big boulders / steel scrap materials, it may be required to shift the pile point from the original location to a new location. In the case of conventional method this wiU cause more loss of time whereas in the invention the change of pile point cam be done in comparatively very less / insignificant time.
Statement of Invention
According to this invention, the excavation method comprises of
i. initial slag boring using vibrating probe by advancing the vibrating
probe into the slag ii. the boring and the formation of pile bore to the flu depth of the BFS
is carried out by the vibratory probe, iii. below the slag, the drilling and the formation of pile bore is carried
out by the rotary drilling rig.
Advantages of the invention
i. In the invention the boring operation for the piling is comparatively
simple, ii. In the invention method, the ping operation requires far less time
compare to the time required by the conventional method, iii. In the invention method, the pie design is cost effective and hence
the cost of foundations is less than the one carried out by the
conventional method.

We Claim
i. boring and formation of pile bore in BFS, using vibratory probe by
Penetrating the vibrating probe through the slag; ii. subsequently below the slag, the pile bore through the soil is formed
by the rotary drilling rig.