Trenching with Drill & Split technology

Trenching by a Hydraulic Piston Splitter    

                     

         A piston splitter can clear hard rocks in trench lines efficiently

                                                                                                                  

  

                   Trenching in rock site takes lots of time and manpower. With a rock drill and a hydraulic rock splitter and an excavator with shovels can clear 60 cube meter rocks per day.

Drill pattern:

A drill pattern( plan ) is based on many factors such as  kind of rock, tunnel size, work duration, the place ( free surface or normal body rock)and the type of equipment you use.

. In case   we make a trench as below photo 1 ( 2m W x 3meter L )  in medium hard rock, the basic spacing is  500mm distance. When the rock is harder than this, you need to keep the space closer ( 500 à 450mm ), When the rock is softer, you can increase the spacing wider.

Photo 2 shows drill plans for 2 meter wide trench excavation.  If the trench starts from top to down ,the first line has 5 holes with the spacing S3, S4,S5 side by side . It is roughly 50cm wide. The second line has 6 holes. Boundary lines on the left and right side have spacing of close distance,i.e 25cm between top to down.

Photo 2 ---- Keep clearing for free face after splitting.

( Plan view of drill pattern- top) and (sectional view-bottom )

” Drilling Angle for keeping “free face

1.      Boundary Line bores: Drill straight  closely along the side lines.

2.      Intermediate bores: Drill slanted so that “free face is kept continuously.

                Diagram 3;  Drill straight in boundary lines( left side, right side)  

 





      

       ( Diagram 3 )  Intermediate bores need slanted drilling to keep free face

The free surface line of top round boundary need be drilled closely with only 20~25㎝ space ( add one in the between normal holes). The free face along the top border line is used for easy breaking of rocks during splitting..

Making free face in the center is another important to keep for continuous splitting . In this case splitting is done from the left  to right .

Manual splitter size of 95㎜ diameter cylinders are recommended. The number of pistons are between 7~9.  Shorter cylinder with 7 pistons are light and efficient.   Longer cylinder with 9 pistons are rather heavy for a manual worker. To assist the lifting splitter , lift is used .

Multi number of splitters are powered by one power pack. Either 4 or 6 splitters are used as a set of machine.  When the width is 2 meter wide, 6 splitters are used in line.

Tips for drilling.

An important tip for drilling of trench is to drill to the targeted depth. In this example, the depth is 3 meter deep.

Rock Splitter recommended,

A manual  rock splitter of 95mm diameter ( HRD 9507, HRD9509 ) is recommended for trenching work.  The number of splitters is considered in terms of width of the trench.

As explained before, splitting in a line covering the whole width saves  lots of time.
When the spacing is made with 50cm distance, 2 meter width wll require at least 5 splitters.

As the splitter length is either 590mm ( SR 9507) or 730mm ( SR9509), each splitter is inserted 4~5 times for splitting. It is usual to see drilling time take more than splitting. So it is recommended to use more powerful splitters than weak ones.

Key Point in Excavation

 In trenching work, a key point in excavation is to  (1) drill  the whole depth  (2) split the drilled line in one shot.  If the ditch depth is 3 meter deep, you need to drill 3 meter deep at a time.  Then splitting is done  from the near line to free face.

 If the splitter length is short of the whole depth, you need to insert the cylinder twice or three times. After the splitting is done ,next line of splitting is tried.

 As seen on above photos, mucking is done just after splitting . This serial work should be arranged considering the each process time. In any case, drilling takes the most of time, splitting time is less than drilling time. Mucking takes the least time.

Performance of hydraulic trenching

Spacing of 50cm between holes.  Drilling time for 3 meter deep hole: 3 minutes.

 Based on above basic assumption, drilling time for 20 holes takes one hour.  Splitting time for 20holes  with 95mm splitters of 6 cylinders 600mm long takes 50 minutes.

So in one hour, 10 cube meter rocks can be drilled and split.   Assuming 20~25% waste time, 60 cube meter of rocks can be cleared in a day time of 8 hours  by hydraulic rock splitting system.