The followings is an example report to be prepared by civil engineer on the slope failure cases.
Project
: KEGAGALAN CERUN DI KM 44, JALAN
SIMPANG PULAI-CAMERON HIGHLANDS ( GUNUNG PASS
) PAHANG
1.0
Introduction
The
Simpang Pulai – Cameron
Highlands
Generally,
the geology of the Gunung
Pass Mount Pass
Kumpulan
IKRAM Sdn Bhd (Contractor) was issued a Letter of Intent on 30.05.2008 to carry
out deep boring works to determine the slip surface depth of landslide at the
KM 44 Simpang Pulai – Cameron
Highlands
Kumpulan
IKRAM Sdn Bhd. is required to assess the location or depth of slip surface of
the landslide at the KM44, Simpang Pulai – Cameron Highlands
2.0
Objective of the Study
The
primary objective of the study is to provide the Government of Malaysia with
the location or depth of slip surface of the landslide at the KM 44, Simpang
Pulai – Cameron Highlands
3.0
Scope of work
Kumpulan
IKRAM Sdn Bhd proposes the following
scope of work that is deemed appropriate to meet the above stated objective.
3.1 To carry out site investigation works
including drilling six numbers boreholes (deep boring works) for depth 90m.
3.2 To carry out geological study of soil and
rock and provide a qualified Engineering Geologist through the duration of the boring
works for the purpose of mapping or recorded the type of soils / rocks, sub- soil profile, the rock fractures and the
location of slip surface along the discovered
samples.
3.3 Kumpulan IKRAM Sdn Bhd shall provide JKR with the Report
explaining engineering
properties of the soils / rocks, sub – soil profile, the rock fractures, the location of probable slip
surface.
3.4 To carry out instrumentation works
including in-situ Field Permeability test in Rock using a Single Packer in N
size diamond drill holes, standpipe piezometer, vibrating wire piezometer and
preparation for TDR.
3.5 To carry out laboratory tests including shear
strength tests, unconfined compressive test (UCS) , petrographic test and other
strength test on rock where necessary.
3.6 To prepare and submit program for the works. The program shall include
deliverable and delivery dates.
3.7 To provide JKR with all materials related
to the works such as data, documents, drawings, photographs and reports both in
digital and hard copies.
4.0 Method of Statement
4.1 Justification for preliminaries and
movement
The
cost of study including drilling works as appendix 2. However we could not use
the SOR as in agreement. The justification for certain items such as
preliminaries and movement of rigs as follows:-
4.1.1 Preliminaries
and General Conditions
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||||||||||
a
|
Insurances
|
42,000.00
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WC
|
}
|
2 % 1,400,000.00
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CAR
|
}
|
|||||||||
PL
|
}
|
|||||||||
SOCSO
|
}
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|||||||||
Special
insured on equipments
|
1.0%
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b
|
Inspection
of Site
|
6,000.00
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c
|
Temporary
Access
|
15,000.00
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d
|
Personal/Workmen
safety (10 person)
|
3,500.00
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||||||||
Safety
boots
|
2500
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Helmets
|
500
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Safety
vests
|
500
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e
|
Compliance
to safety plan and Environment Impact Assessment (EIA)
|
10,000.00
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||||||||
f
|
Watching
and security at site@ 2 months
|
10,000.00
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g
|
Workmen’s
Accommodation@ 2 months
|
20,000.00
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||||||||
h
|
Transportation
for water and fuel
|
5,000.00
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||||||||
i
|
CIDB
Levi
|
3,500.00
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j
|
Site
clearance and rehabilitation of site after completion of works
|
5,000.00
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k
|
Storage for core samples/core boxes
|
10,000.00
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Total
|
130,000.00
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4.1.2 Movement
Breakdown
of movement from BH to BH (7 days)
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||||||
Personal
/ workers (10 person)
|
10,500.00
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|||||
Salary,
OT and allowances
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||||||
RM1,500/day
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||||||
Rental
of bulldozer / excavator
|
17,500.00
|
|||||
RM
2,500/day
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||||||
Fuel
consumption for boring machine
|
2,500.00
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|||||
Total
|
30,500.00
|
|||||
Profit
and attendance (15%)
|
4,575.00
|
|||||
Total
|
35,075.00
|
|||||
Downtime
(loss of time)
|
9,000.00
|
|||||
Total
|
44,075.00
|
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4.1.3 Methodology
of movement
A feasible study on the site condition was carried
out during the site visit. Based on the study it was reckoned that there were
two possibilities of accessing to the positions; either by tracking the most
suitable access through a longer route that will take a longer time to reach or
by using an excavator half way the mount and then dismantle the components of
the boring machine to bring them manually to the test positions. Either way
both methods will consume time and energy. Every shift has to be assessed
separately on a case to case basis based on site and confidence of the team.
The element of risk cannot be discarded. (See appendix 3 and 4 for details)
4.2 Safety and health plan
All safety measures and work procedures shall comply
with OSHA requirements. IESSB shall not compromise on the safety aspects when
carrying out the S.I works.
All forms of digging and cutting of soil shall be
carried out in a manner to ensure minimum disturbance to the ground and environment
4.2.1 Objective
To
conduct operation in such a manner so as to avoid harm to employees and all others
who may be affected by the Site Investigation activities.
(a)
To
maintain the highest practically achievable standards of safety occupational
health and environmental protection.
(b)
The
company’s safety targets are :
-
Zero fatalities and minimal environmental
damage.
- To prevent any
accident by pre planning and implementing the safety system.
- To create safety awareness amongst all staff
- To protect the
environment on land from accidental contamination and damage.
4.2.2 Risk
Protection
4.2.2.1 Personal Health
a)
High
standard of hygiene is expected at all work places.
b)
Cuts
and abrasions should be cleansed at once and given
first aid treatment.
c)
Proper
first aid kit shall accompany the field crew at all
times.
4.2.2.2
Personal
Protective Equipment (PPE)
a)
Appropriate
PPE shall be worn in consistent with the
hazard :
(i)
long
sleeve shirt
(ii)
gloves
(iii)
high-top
boots
(iv)
helmets
(v)
reflective
safety vest
4.2.2.3 Traffic Safety
a)
All
personnel shall comply with traffic rules whether
on
land or water.
b)
Drivers
must be in possession of valid driving
licenses.
c)
Night
driving is to be avoided whenever possible.
d)
Only
authorized personnel may drive company
vehicles.
4.2.2.4 Storm
Lightning
usually strikes the highest point or object in any area because it is seeking
the shortest path. The following precautions shall be taken when a storm is
approaching:
a)
Inform
the CSA / STE of the storm and suspend all
operations
b)
Drop
all metal tools, pipes and cables
c)
Take
shelter. Stay away from trees; if possible take
shelter inside a vehicle parked in a low
open area rather
than under trees.
4.2.2.5 Shifting of machinery in difficult terrain
a)
All
personnel shall take necessary precaution to ensure
the mast is lowered during shifting.
b)
Ensure
minimum disturbance to soil and loose boulders
when moving equipment and machinery.
c)
Always
be alert for rolling boulders or possible landslides
d)
Use
only the proper cable or rope to move the boring
machine.
e) When moving the machine up a steep grade,
anchor all
lines.
4.2.2.6 Emergency Procedures
In case of
injury or illness the site Agent is to be contacted and informed of:
- Nature of the accident / incident
-
Seriousness
of injury
-
Whether
medical assistance is required
- Administer
first aid if necessary
- Investigate cause of accident / incident
- Report to CSA / STE
- Ensure a vehicle is on standby at the
test location at
all times.
4.3 Role of geologist
4.3.1 Objective:
The
objective of work:
1)
To
carry out Geological mapping of the project area
2)
To
record the type of soil/rocks and sub soil profile
3)
To
record the rock fractures and the location of slip surface along the discovered
samples
4)
To
carry out full time supervision by Geologist at site
4.3.2 The method
of work:
1)
Methodologies for the geological mapping with recording detail
data; by choosing sections with a lot of rock outcrops. This geological mapping
use appliance of topographic map of this area, geological compass, hammer,
measuring tape, digital camera and GPS. Final report of the geological mapping
is “Geological Map” of the project area. This map contains various type of rock
and strata graphic of rocks from the bottom towards top.
2)
Methodologies for the recording detail data of rocks, sub soil and
soil; with many detail sections from the bottom to the top. This detail
sections use appliance geological compass, measuring tape, digital camera and
GPS. The final report of this method will get rock formation from bottom to the
top; it is including fresh rocks, weathering rocks and top soil.
3)
Methodologies for the recording detail data of rock fractures and
slip surface; with detail measurements along the every area of rocks fractures
and failure (slip surface) of the location of probable slip surface. This
measurement use appliance, such as geological compass, tape and digital camera.
Data recording are processing with the stereo and stereographic program to
determine many type of slip surface and lineament or arrow of slip
surface.
4)
The C.V of the Geologist is as attached in appendix 9.
4.4 Field Exploration
4.4.1 Procedure
All
drilling works and test procedures shall be carried out in accordance with MS
2038:2006 , BS 5930:1999 and all laboratory testing shall comply with MS 1056
4.4.2 Deep Boring
4.4.2.1 Deep Boring Plant
The Boring
Plant to be used is a ‘YWE D90R’ which is capable of boring and drilling to a
depth of 100 metres using N size casings. It is a light machine and can be
winched along the slopes using trees to hold. But , however, it is not suitable
to drill to a depth of 90 metres using H size casings due to its limited
capacity.
To drill into
rock/ soil using bigger size casings
like the H or P sizes, a more powerful and bigger machine is more suited. But,
however, bringing the bigger rig to the proposed site at the summit of the
mount is not possible due to its size and weight. The terrain is too steep for
such machines. It may pose a safety problem and endanger the lives of the
workers and also the road users below.
4.4.2.2 Method
of Advancing Boreholes – Wireline drilling and
Sampling
Kumpulan IKRAM
Sdn Bhd proposes that the wireline drilling and sampling method be used to
advance the boreholes.
The main
difference between wire-line drilling and conventional core drilling equipment
is the drilling rods. Wire-line drill rods are thin hollow tubes known as ‘Q’
drill rods. The rods are hollow to allow the inner core barrel, over-shot
assembly and wire-line to pass through them. Wire-line core drilling is
basically the same as conventional drilling rods and core barrel. A diamond
drilling rig with all other accessories is required.
Core barrel
can be raised on a wire-line without removing the entire string of rods, as in
the case of conventional core drilling. This is done by lowering the overshot
assembly down the hole on the end of the wire-line. The overshot graps the
inner barrel which can then be brought to the surface to remove the core. The
inner barrel can then be lowered back down the hole where it fits into the
outer core barrel and is in position to retain another core once the drilling
is resumed. The drill rig must include a wire-line hoist in this operation .
Wire-line
drilling is faster and cost effective for deep core drillings (please see
appendix)
4.4.2.3 Size and Depth of Boreholes
The size of
boreholes would be about 76mm. in diameter. It would be such that all the
requirements of the sizes in sampling, in-situ testing, etc are satisfied.
4.5 Rock Drilling
4.5.1 The
procedure for rock drilling
The procedure for rock drilling shall be
carried out in accordance with BS 5930 : 1999. The diameter of the core barrel
used shall be such as to produce a rock
core of about 50.0mm diameter that of
NQ core barrel. The Core Recovery Ratio (CRR) and the Rock Quality
Designation (RQD) shall also be reported for each core run.
The CRR means the ratio of the total length
of good quality core over the drilling length expressed to the nearest 5%. The
RQD is the ratio of the total length of the good quality core each exceeding
100mm in length over the drilling run correct to circular circumference or in
the case of broken rock fragments assembled to form cores with circular
circumference.
4.5.2 Preservation, Storage and Transportation of Rock Cores
Core samples shall be stored in the standard
core boxes clearly labeled to show the drilling sequence. Any discontinuity in
the core shall be clearly noted. The name of the project and borehole number
printed on the cover.
All
rock cores shall be kept at IKRAM Central for a period of 6 months for the S.O.
to inspect.
Samples
of cores randomly to be sent to approval laboratory and or JMG Ipoh/UKM (Jabatan
Geologi) for identification type of rocks.
4.5.3 Limitation
of Rock Core size
As
requested by JKR rock core size 75mm Ø for the whole depth of 90 meters could
not be obtained due to the limited capacity of the boring machine.
5.0 Instrumentation and Monitoring Works
5.0.1 Packer
test (Permeability test in rock)
5.0.1.1 General Principles
The packer or
Lugeon test gives a measure of the acceptance by in-situ rock of water under
pressure. The test was originally introduced by Lugeon to provide a standard
for measuring the impermeability of grouted ground; it is also widely used as a
packer test to measure the permeability of dam foundations. In essence, it
comprises the measurement of the volume of water that can escape from an
uncased section of borehole in a given time under a given pressure. Flow is
confined between known depths by means of packers, hence the more general name
of the test. The flow is confined between two packers in the double packer
test, or between one packer and the bottom of the borehole in the single packer
test. The test is used to assess the amount of grout that rock accepts, to
check the effectiveness of grouting, to obtain a measure of the amount of
fracturing of rock, or to give an approximate value of the permeability of the
rock mass local to the borehole.
The results of the test are usually expressed in terms of
Lugeon units. A rock is said to have a permeability of 1 Lugeon if, under a
head above groundwater level of 100 m, a 1 m length of borehole accepts 11/min
of water. Lugeon did not specify the diameter of the borehole, which is usually
assumed to be 76 mm, but the test is not very sensitive to change in borehole
diameter unless the length of borehole under test is small.
A simple rule that is sometimes used to convert Lugeon
units into permeability is to take one Lugeon unit as equal to a permeability
of 10-7 m/s. An approximate value of permeability may also be
calculated from the following formula, although the assumptions on which it is
based are not always borne out in practice.
Q L
k = 2p HL loge r
where,
k is the permeability in metres per second
(m/s);
Q is the rate of injection in cubic metres
per second (m3/s);
H is the pressure head of water in the test
section in metres (m);
L is the length of the test section in
metres (m);
r is the radius of the test section in
metres (m).
Tests to assess permeability by means of packer tests are
usually carried out at varying values of Q
and H, and the value of k determined from the slope of the flow
versus pressure graph.
5.0.1.2 (Pneumatic) Packers
This comprises a rubber
canvas duct tube, which can be inflated against the sides of the borehole by
means of pressurized gas. Bottled nitrogen or compressed air is fed down the
borehole through a small diameter nylon tube. The inflation pressure should be
that required to just inflate the packer to the required diameter, to seat the
packer and to overcome the hydrostatic pressure in the borehole. Excessive
pressures should be avoided. The difference between the diameter of the
uninflated packer and the diameter of the borehole should be such that the
packer can be easily inserted. At the same time, the inflated diameter of the
packer should be sufficient to prove an efficient seal. A double packer is two
packers connected by a length of pipe of the same length as the test section.
The test water is introduced between the packers.
5.0.1.3 Application and measurement of pressure
It is essential that the maximum water pressure to
be applied is not sufficient to cause uplift of the ground or to break the seal
of the packers in deep holes in weak rock. The pressure to be determined for
use in the calculation of permeability is that causing flow into the rock
itself. The pressure can be measured directly with an electric pressure gauge
set in the test zone or indirectly by gauges at ground level. The use of direct
pressure measurement is preferred and pressures should be measured at the
bottom and preferably below the test section. This avoids the difficulties
associated with corrections for fluid density, friction losses etc. in indirect
measurements. If it is necessary to take indirect readings at ground level,
these are adjusted in accordance with the following expression:
HT
= P + (H – Hg) – Hf
Where
HT
is the pressure head causing flow
into the rock in metres (m);
P is the Bourdon gauge reading converted
to head in metres (m);
H is the height of Bourbon gauge above
mid-point of test section in metres (m);
Hg
is the height of natural groundwater
level above mid- point of test
section in metres (m);
Hf is the
friction head loss in the pipes in metres (m).
5.0.1.4 Measurement of flow
The
rate of flow of water may be measured either by a flow-meter or by direct
measurement of flow out of a tank of known dimensions by means of a dipstick or
depth gauge. Where a flow-meter is used, it should be installed upstream of the
pressure gauge, well away from bends or fitting in the pipe-work, and in
accordance with the manufacturer's instructions. The accuracy of the meter
should be checked before the test begins, and periodically afterwards, by
measuring the time taken to fill a container of known volume at different rates
of flow. Where the flow out of a tank is to be measured, the use of one large
tank can lead to inaccuracies where the plan area is large and the fall in
level correspondingly small. A better arrangement is to use a number of small
containers.
5.0.1.5 Execution of test
Developing
or cleaning the borehole before testing is vital. The test may be carried out
either as a single or as a double packer test. Appropriate measurement devices
should be included to allow detection of leakage past the packers; this is
assisted by continuous logging of the readings. However, the single packer test
is normally done periodically during the drilling of the hole, which makes it
more costly. An important point is to ensure that the packer is properly seated
in the boreholes. Where a complete core has been recovered from the borehole,
or where appropriate logging or television inspection has been carried out, a
careful examination may reveal suitable places to seat the packer. Where the
seating proves unsatisfactory, the length of the test section should be altered
or test sections overlapped, so as to seat the packer at a different depth in the
borehole.
Because
of the limitation on the pressure referred to in 3.0, it may not be practicable to run the test at the (Lugeon)
specified head of 100 m above groundwater level. The assumption is made that
the water flow is proportional to the pressure, although this is not
necessarily true. It is then possible to obtain the Lugeon value by
extrapolation. For hydrogeological purposes, test pressures of less than about
5 m head are usually adequate. It is customary to run a series of tests at
different pressures. Typically a series of five tests is desirable, with the
maximum pressure applied in three or five equal increments and then reduced
with decrements of the same amount. The full data record obtained from these
measurements is particularly useful in assisting in the interpretation of the
behaviour of the rock under test. ( see Appendix 5)
5.1 Ground water
monitoring
5.1.1 Standpipe
Piezometer
Standpipe Piezometers shall be installed in selected
boreholes as instructed by the Engineer. The final details of any piezometer
installation shall be decided by the Engineer.
The piezometer tip shall consist of a porous ceramic
element or other suitable element not less than 150 mm long with a diameter not
less than 40mm, and shall be protected at each end by unplasticised
polyvinylchloride ( upvc ) fittings. The ceramic shall have a pore diameter of
the order of 60 microns and a permeability of the order of 3 x 10-4
m/s.
The tube shall be jointed together and to the porous
element with approved couplings and glued is such a manner that the joint
remain leak proof under the anticipated head.
5.1.1.1 Grouting
A grout of cement and bentonite in the proportions
of 1:4 shall be used. If water in the exploratory hole is contaminated by grout
it shall be replaced by clean water, the method being to the approval of the
Engineer.
5.1.1.2 Sand Filter
The sand filter surround to the porous element shall
be clean and fall wholly between the limits of grading 1200 and 210 microns and
the volume of sand filter placed shall be recorded. The final elevation of the
top of this sand shall be recorded. The porous element shall be placed in the
hole and the remaining sand filter shall then be added as described above.
5.1.1.3 Surface Installation
The top of the UPVC tubing shall be covered by a
plastic cap or similar as approved by the Engineer. An air vent shall be
provided. Arrangement to protect the top of the UPVC tubing shall consist of a
steel barrel of 75mm diameter which shall be set in concrete.
5.1.1.4 Water Level
The ground water level shall be recorded immediately
before and after installation of the piezometer. Before readings are commenced,
the piezometer shall be filled with water and its correct functioning
demonstrated to the Engineer. Each peizometer shall be clearly and permanently
labeled giving the exploratory hole a reference number. During field works the
ground water level in the standpipes piezometers shall be recorded. (see
Appendix 6)
5.2 Vibrating Wire Piezometers
5.2.1 General
The basic principle of operation is that a porous element is placed in
the ground so that the soil water is continuous through the pores of the
element, and this water is collected in a container unit. The pressure of the
water in the container unit is recorded, and hence the water pressure in the
ground is determined.
The Vibrating Wire (VW) piezometer comprises of a porous tip which
contains a pressure –sensitive diaphragm, a tensioned steel wire and an
electro-magnetic coil. One end of the wire is concreted to the diaphragm and
the other to the body of the piezometer.
Pressure causes the diaphragm to deflect, reducing tension in the wire.
The magnetic coil is used to ‘pluck’ the wire, causing it to vibrate.
The vibration of the wire near the coil generates a frequency signal that
is transmitted via a signal cable to the readout unit.
5.2.2 Equipment
a)
Drill rig capable of drilling a hole of 100mm ID (
HW casing ) to the required depth
b)
Vibrating Wire (VW) piezometers with High Air Entry
or Low Air Entry ceramic filters, and signal cable.
c)
Installation tools and materials, geotextile bag,
sieves 1.18mm and 600 um
d)
Vibrating Wire (VW) data recorder
e)
Protective device made of steel and lockable to
cover the top of the borehole to minimize vandalism.
5.2.3 Drilling of
Hole
The size of the borehole is 100mm ID and is drilled with the use of
water. Steel casing is used when necessary to prevent the collapse of the
borehole.
The borehole is advanced to the specified depth as near vertical as
possible, and the borehole flushed with water to clean the hole.
5.2.4
Vibrating Wire (VW) piezometers Installation
The VW
piezometer tip is immersed in cooled boiled water(de-aired water) for at least
24 hours to saturate the ceramic filter. It is then placed in a geotextile bag
filled with clean sieved sand (passing 1.18 mm, retained on 600µm)
This operation
is carried out with the piezometer underwater at all times. The whole assembly
is left in de-aired water until just before placing in the borehole.
The use of the
geotextile bag filled with sand is to prevent the clogging up of the ceramic
filter of the piezometer during installation, and also it provides a minimum
thickness of clean sand between the ceramic filter and the soil should the
assembly for some reason cannot be placed in the centre of the borehole (this
system in fact allows the piezometer to be placed more accurately in the centre
of the borehole)
Ten to fifteen
minutes after the piezometer has been lowered to the required depth, a reading
is taken using the VW Data Recorder to check whether the piezometer is
functioning or not.
Clean, sieved
sand (passing 1.18mm and retained on 600µm BS test sieves) is poured into the
borehole until a layer of sand is obtained at the bottom of the borehole (the thickness
will be as directed by the Engineer)
The piezometer
is lowered into the borehole and placed on that layer of sand. More sand is
then poured in until the piezometer is covered by a layer of sand of thickness as directed by the Engineer.
A bentonite
plug is formed above this sand layer, and this sand layer by slowly dripping bentonite
pellets of 0.5 inch diameter.
The thickness
of this plug will be as directed by the Engineer. The rest of the borehole is
the then grouted to ground level with a pumpable cement – bentonite mix (4.1)
The thickness
of the various layers are measured using a measuring tape weighted down with a
heavy weight, and lowered into the borehole periodically.
Each borehole
will have only one piezometer and the piezometers will be marked at the end of
the signal cable at ground level with tape bearing identification numbers
written with permanent ink as directed by the Engineer.
5.2.5 Monitoring
of the VW Piezometer
Present day
vibrating wire indicators incorporate automatic features which simplifies the
taking of readings.
To read the pressure,
the signal cable of the piezometer is attached to the indicator box, and the
pressure or frequency read from the digital gauge. (see Appendix 8)
5.3 Preparation of Time Domain
Reflectrometry Holes ( TDR )
Time Domain Reflectrometry holes shall be constructed , as instructed by
the Engineer. The final details of any Time Domain Reflectrometry hole shall be
decided by the Engineer.
The Time Domain Reflectrometry hole shall consist of a 50mm diameter unplasticised
polyvinylchloride ( UPVC ) tube jointed together with approved couplings and
fitted with an end cap. It is placed in a pre-bored hole through the whole
length of the hole with about a metre of the UPVC sticking out of the ground at
the surface. The UPVC shall be packed with cement bentonite grout in the
proportion of 1:4.
A coaxial cable ( RG8) of approved quality with an
outer diameter size of 10mm, as specified by the Engineer shall be affixed
firmly to a 1kg weight at one end. The size of the weight shall be such that it
can be placed at the bottom of the 50mm diameter UPVC tube with the cable
positioned centered and as near vertical as possible.
The inner part of the UPVC tube with the coaxial
cable shall be grouted with bentonite cement grout in a proportion of 1:9.
5.4 The
Monitoring of work starts after completion of field works on per trip basis
irrespective number of different test.
6.0 Work programme
The
whole S.I works will take about 6 months to complete including instrumentation
works. ( see appendix 1)
7.0 Financial
costing
The
proposed S.I works is estimated to cost about RM 1.4 million.
Items
that are not in SOR are subject to approval by JKR.
( see appendix 2 )
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