2013-12-31 - @preliminary report - kawasan industri akr - improvement menthod

8/12/2019 2013-12-31 - @Preliminary Report - Kawasan Industri Akr - Improvement Menthod

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AKR INDUSTRIAL ESTATE - GRESIK

EAST JAVA, INDONESIA

INITIAL REPORT

FOR

AKR INDUSTRIAL ESTATE

AT

GRESIK, EAST JAVA

GROUND IMPROVEMENT SCHEME

Document No : ILSIWJKT24001/001

REV DATE PREPARED BY REVIEWED BY APPROVED BY

NAME SIGN DATE NAME SIGN DATE NAME SIGN DATE

00 LY 29/12 MD 29/12 LR 29/12


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TABLE OF CONTENT

I. INTRODUCTION .......................................................................................................... - 3 -II. SITE AND SOIL CONDITION .................................................................................... - 4 -III. GROUND IMPROVEMENT METHODS................................................................... - 8 -IV. GROUND IMPROVEMENT RESUME .................................................................... - 15 -


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I. INTRODUCTIONThis document describes various method of ground improvement may apply for roadconstruction at AKR Industrial Estate, Gresik, East Java.

Key Plan

The detail calculation will perform by PT. Geotekindo after more discussion with owner

about their need and technical requirement of the area.

This report is produced based on the following documents :

Block Plan. Soil properties. Boreholes. Oral explanation about the requirement.


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II. SITE AND SOIL CONDITIONBLOCK PLAN

Area is dividing in 4 section named M-1, M-2, M-3 and M-4. Map below shows the block

plan.

Block Plan

Base on oral information from consultant, it state area M-1 already backfill use limestone

with 1 m thickness but quite bouncy. Area M-2, M-3 and M-4 not prepared yet (swamp or

fish pond) and later will backfill use limestone as in M-1.


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SOIL DATA

Typical boreholes for M-1


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Typical boreholes for M-2 and M-3

Here we can see the soft clay depth about 1012 m from surface. The soft clay has CPT

between 0 to 2 means it has a very low bearing capacity.

Base on lab test, Compression Index (Cc) value around 0.8 to 1.1 means its a highly

compressible layer.


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LOAD PLAN, ASSUMPTION, CROSS SECTION AND PROPOSE METHOD

Base on drawing, ROW is 80 m : road, drainage, infrastructure space and open area. In

our opinion the ground improvement should only focus on road area because its the only

area bearing a high traffic load.

The assumption below is use in proposal :

ROW : 80 m. Road section : 15 m x 2 = 30 m. Road length : 6.000 m Road area : 180.000 m2. Traffic load : 3.5 t/m2. Road structure : 27 cm concrete + 0.15 m base + 0.60 limestones.

Total permanent load is (0.27*2.4 + 0.15*1.8+0.60*1.8)= 2.0 t/m2.

Total load : 3.5 + 2.0 = 5.5 t/m2. Total preload : at least 7.0 t/m2. Soft soil depth : average 10 m. Soft soil type : Clay. Base material : limestone is preferred by owner. Working hours : 2 shift. Construction : finish at 9 September 2014. Ground level : +0.00 (treatment final level)

Above +0.00 is the layer of Road Structure construction

Here we propose several methods as mention below. In each section it will describe

advantage and disadvantage of each method and estimated cost and schedule.

Propose method are :

1. Soil Preloading2. Vacuum Preloading3. Stone Column4. Dynamic Replacement


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III. GROUND IMPROVEMENT METHODSSOIL PRELOADING

Soil preload method is a well-known conventional ground improvement. Here we only

shows the work sequence, construction cost and duration. The calculation is based on

10.000 m2 area.

Schedule :

Area : total 18.000 m2 divide by 6 sub-zones with 3 Ha each.

Work group : 3 groups.

PVD installation : 8.000 m / unit / day.

PHD installation : finish 2 weeks after PVD installed.

Soil backfill : max 1 m thickness / week to avoid sliding.

Consolidation : 6 months.

Start to finish : 11 months.

Overlapping with road construction : No.

Notes :

The width of road need to improve is 30 m width only. However it need to backfill more

than 30 m for the berm area. Here we assume slope is 1: 2.

At M-1 there is limestone backfill. This limestone should remove before proceed PVDinstallation.


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VACUUM PRELOADING

The vacuum preloading method or vacuum consolidation method was firstly proposed by

Kjellman in 1952 for treatment of the soft soil strata. Now the vacuum consolidation

method has become a popular technology in the soft soil improvement work in East Asia.

The principle of the method is that when vacuum pressure is induced into the soil, it will

not only drain water but also atmosphere out of the improving site. Thus, it accelerates the

soil consolidation process, reduces the construction time and increases the soil stability.

The design and the construction work of the method of the must follow standards.

Execution Process of Vacuum Preloading Method is show clearly in picture below.

1. PVD installation 2.

Geomembrane

installation

3. Monitoring

equipments

installation

4. Vacuum +

surcharge

preloading

Construction process of vacuum consolidation method

Here we shows the work sequence and improvement cost.


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Schedule :


Work group : 3 groups.PVD installation : 8.000 m / unit / day.PHD installation : finish 2 weeks after PVD installed.

Soil backfill : can backfill fast as possible.

Consolidation : 3 - 4 months.

Start to finish : 6 months.

Overlapping with road construction : No.

Notes :

The width of vacuum area same with road width of 30 m.

At M-1 there is limestone backfill. This limestone should remove before proceed PVD

installation.


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STONE COLUMN

Stone column construction aims to provide a high bearing capacity and reduce post

settlement by reinforce method. Here we propose stone column construct by vibro-

displacement. Picture below shows the work sequence.

Assumption :

Stone column diameter : 1 m Stone column distance : 2 m, square. Stone column depth : 5 m and 10 m. Installed alternating. Stone size : 37 cm. Clean stone. Top surface :0.5 m of limestone (not include limestone for

road structure).

Here we shows the work sequence and improvement cost.


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Schedule :



Install capacity : 240 m / unit / day.

Start to finish : 5 months.Overlapping with road construction : Yes.

Notes :

Minimum Su of original soil is 25 kPa.

Bearing capacity of each stone column is 15 t of each stone column with 0.80 m2 surface

area.


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DYNAMIC REPLACEMENT

Dynamic Replacement construct use special crane for dynamic compaction. The aim is to

make a dense top layer with a short column which construct by hit the limestone material

use special hammer and let it penetrate the soft soil.Typical depth of penetration is 3.0 m (below the stone layer) with diameter about 2.5 3.0 m.

Picture below shows the work sequence.

Assumption :

Column diameter : 2.53.0 m. Use 2.75 m as average. Column distance : 3.5 m, square. Column depth : 3 m under the limestone layer. Stone type : Limestone. Top surface :0.5 m of limestone (not include limestone for

road structure).

Number of hit : 2025 hit / point.Here we shows the work sequence and improvement cost.


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Schedule :

Area : total 18.000 m2 divide by 8 sub-zones with 2.25 Ha each.


Work cap : 4050 minutes / column / unit.

Productivity : 147 m2 of area / unit / day.Start to finish : 5 months.Overlapping with road construction : Yes.

Notes :

Bearing capacity of each column about 80 t of each column with 7.56 m2 surface area.

There is 45 m soft soil layer under the column which may still contribute for long term

settlement. However this soft soil already improved due to replacement effort.

Long term settlement is estimated about 20 cm.


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IV. GROUND IMPROVEMENT RESUMETable below shows the comparison between methods.

2013-12-31 - @preliminary report - kawasan industri akr - improvement menthod

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