Report on Embankment Distress Remedial Work Submit

8/2/2019 Report on Embankment Distress Remedial Work Submit

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1.0 GENERAL DESCRIPTION OF PROJECT

1.1 General

Jabatan Kerja Raya Negeri Perak intend to construct the road (JKR R3 Standard

single carriageway) connecting Alor Pongsu and Bukit Merah, Perak. The approximatelength of the road is about 7.0 km. The proposed road would bring social benefic to the

local community by establishing a local road network for subsequent integration into the

state transportation system.

2.0 EMBANKMENT DISTRESS

2.1 Introduction

During the construction of the road embankment along the stretch of the road

there are several occurrence of embankment distress. The first occurrence happened at

CH4100-CH4250 on 3 August 2010 and then the second happened at CH100-CH240 on

12 November 2010. The third occurrence happened on 2 December 2010 at CH260-

CH400, and the last occurrence happened at CH2720-CH2860.

2.1.1 CH4100-CH4250

Figure 1 Cracks propagated from the centerline towards the right hand side of the carriageway


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The embankment fill heights between CH4100 and CH4250 are less than 2.0m.

The fill height ranges from less than 0.5m to about 1.5m above the original ground. The

prescribed ground treatment at the area was removal of 1.5m thick unsuitable material

and replaced with suitable fill and sand in the ratio of 70:30. Non-woven geotextile

Polyfelt TS40 has been prescribed as separator.

2.1.2 CH100-CH240

The embankment fill heights between CH100 and CH240 are in the range of 1.5m

to 3.1m above the existing ground level. The prescribed ground treatment was Partial

Removal and Replacement of 1.5m unsuitable material, and surcharge. Surcharge fill

height was 1.0m high and the surcharge period was 3 to 6 months. Basal reinforcementwith woven geotextile Polyfelt PEC100 was specified in the drawing.

Figure 2 Cracks have propagated from the edge of carriageway towards the embankment toe


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2.1.3 CH260-CH400

The embankment fill heights between CH260 and CH400 are in the range of 1.5m

to 3.1m above the existing ground level. The prescribed ground treatment was Partial

Removal and Replacement of 1.5m unsuitable material, and surcharge. Surcharge fill

height was 1.0m high and the surcharge period was 3 to 6 months. Basal reinforcement

with woven geotextile Polyfelt PEC100 was specified in the drawing.

Figure 3 Cracks propagated at the centerline towards the right and left hand side of the

carriageway


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2.1.4 CH2680-CH2760

The embankment fill heights between CH2680 and CH2760 are in the range of

1.5m to 3.1m above the existing ground level. The prescribed ground treatment at thearea was removal of 1.5m thick unsuitable material and replaced with suitable fill and

sand in the ratio of 70:30. Non-woven geotextile Polyfelt TS40 has been prescribed as

separator.

3.0 EMBANKMENT DISTRESS REMEDIAL METHOD

3.1 Recommendation by Consultant

It is proposed that the following remedial action be carried out to the embankment

distress/ failure areas.

Remove the loose fill material

Reconstruct the slope with 2 layers of reinforced geotextile (woven

geotextile) Tencate/ Polyfelt PEC200 (or equivalent)

Figure 4 Cracks propagated from the left hand side of the carriageway towards the right hand side

of the carriageway


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Surcharge period of 3 month with rod settlement gauge installed to

monitor the progress of settlement

A filling rate restriction of 0.5m per week

The proposed remedial works is presented in Appendix B.

APPENDIX 1 Proposed Remedial Work

2 LAYERS OF POLYFELT PEC200 (OR

TYPICAL SECTION FOR REMEDIAL WORK USING GEOTEXTILE

DETAIL 'A'


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4.0 EMBANKMENT DISTRESS REMEDIAL WORK

4.1 Embankment Distress Remedial Work Method Statement

4.1.1 Joint Survey

A joint survey first conducted by contractors site engineer and JKR

representative to determine the existing reduces level of the distress embankment

before an excavation works starts.

4.1.2 Excavation and Backfilling Work

The excavation of the distress embankment has been determined to specificrequirement. The depth of the excavation is 2.5m from the top of the existing

embankment. The width of the excavation is 11.0m from the centerline to both left

and right hand side of the proposed carriage way.

The loose soil of the excavation is dumped nearby. When there are sufficient

excavation areas for laying reinforced geotextile, one layer of reinforced

geotextile PEC200 then spread on the ground. The step then repeated, the end of

two reinforced geotextile sheets will be sewn 3 times using electric powered hand

sawing machine. This will ensure no puncture between the reinforced geotextile.

Figure 5 Excavation and backfilling works


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The loose soil excavated and dumped before, then be used as the filling

material. The soil will be dumped on the reinforce geotextile which has been lain

earlier and will be spread and leveled to the whole area using tractor/backhoe. The

thickness of the soil spread is ensured not exceeding 0.6m. During this process,

rod settlement gauge installed at the desired position.

Figure 6 Sewing process

Figure 7 Spreading and leveling soil


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4.1.3 Soil Compaction Work

Soil compaction is the method of mechanically increasing the density of soil.

If performed improperly, settlement of the soil could occur and resultingembankment failure. In order to achieved the desired strength to carry the

intended embankment loading, the soil that spread and leveled before has been

properly compacted using vibratory smooth drum roller. Besides that well

compacted soil may reduce water seepage and provide stability.

Vibratory force uses a mechanism, engine-driven to create a downward force

in addition to the machine's static weight. The vibrating mechanism is the rotating

eccentric weight or piston/spring combination. The compactors deliver a rapid

sequence of blows (impacts) to the surface, thereby affecting the top layers as wellas deeper layers. Vibration moves through the material, setting particles in motion

and moving them closer together for the highest density possible.

Figure 8 Compaction work using vibratory smooth drum roller


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4.1.4 Constructing Second Layer of Fill Material

Once completed, the process continued with second layer of fill material. The

reinforced geotextile sheet laid before then folded onto the soil that has been

compacted.

Then another layer of reinforced geotextile PEC200 spread on the compacted

soil. The step then repeated, the end of two reinforced geotextile sheets will be

sewn 3 times using electric powered hand sawing machine. This will ensure no

puncture between the reinforced geotextile.

The soil then fill onto the reinforced geotextile layer that sewn before. The

step is almost the same as the previous backfilling method. The loose soil from theexcavation before reused as the backfilling material. Since the quantity of soil is

inadequate, imported soil from nearby borrow pit required. The soil is transferred

using lorries. The soil then spread and leveled to the whole area using

tractor/backhoe. The thickness of the soil spread is ensured not exceeding 0.6m.

Figure 9 Reinforced geotextile that be folded onto the compacted soil


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Figure 10 Backfilling earth to form second fills layer

Figure 11 Imported soil from nearby borrow pit


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Soil compaction process is continuously done after the soil is spread and

leveled. The step is almost the same as the previous compaction work.

Figure 12 Continuously soil compaction process

Figure 13 2nd layer of reinforced geotextile be folded and backfilling with soil


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4.1.5 Constructing Third, Fourth and Fifth Layer of Fill Material

The construction of third, fourth and fifth layer of fill material is a repetitive

sequence of constructing second layer fills material, the different when backfilling

soil to form third layer is that there is no more reinforced geotextile laid on theground. After the second layer reinforced geotextile be folded the loose soil can be

dumped on it. Since the quantity of soil is inadequate, imported soil from nearby

borrow pit required. The soil is transferred using lorry. The soil then spread and

leveled to the whole area using tractor/backhoe. The thickness of the soil spread is

ensured not exceeding 0.6m. Then extensively compaction process did to the fill

material layer. The steps are repeated to the fourth and fifth layer.

4.1.6 Constructing SurchargeThe construction of surcharge load is also a repetitive process of layer fourth

and fifth. The filling earth for the surcharge is divided into two layers. There is

restriction for filling rate of 0.5m per week. During the construction of the first

surcharge level, the soil is spread and level not exceeding 0.5m, the soil then

compacted using vibratory smooth drum roller. The process is repeated during the

construction of second layer surcharge load.

Figure 14 Compaction work on surcharge load


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Report on Embankment Distress Remedial Work Submit

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