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GOVERNMENT OF INDIA
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MINISTRY OF RAILWAYS
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Consultancy Report
On
Rehabilitation Of Weak Formation
Between
Pandrasali And Rajkharswan Stations
Chakradharpur Division: South Eastern
Railway
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Consultancy No. RDSO/2008/GE:CR-
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May 2008
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Geo-technical Engineering Directorate
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Research Designs & Standards Organisation
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Consultancy Report on Rehabilitation of weak formation between Pandrasali & Rajkharswan stations, SER
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I N D E X
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Particulars
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Preface
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Synopsis
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Introduction
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References
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Scope of work
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History
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Track Structure
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Details Of Soil Samples
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Slope Stability Analysis
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Site Inspection And Collection Of Field Data
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Analysis & Discussion Of Test Results
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Formulation Of Remedial Measures
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Recommendations
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Annexure I ( Lab test results of soil samples)
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Annexure II ( Slope stability analysis)
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Annexure III ( Slope stability analysis)
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Consultancy Report on Rehabilitation of weak formation between Pandrasali & Rajkharswan stations, SER
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SYNOPSIS
The double line section between Pandrasali and Rajkharswan stations
Chakradharpurr Division of South Eastern Railway is posing problem
in track maintenance due to weak formation at number of
intermittent locations having maximum permissible speed of the
section as 80 kmph.
On the request of South Eastern Railway, detailed field investigations
between Pandrasali and Rajkharswan stations was carried out along-
with testing of field’s undisturbed/disturbed soil samples at RDSO.
Present Report includes suggested remedial measures for
rehabilitation of weak formation on two such stretches on the above-
mentioned line. Recommendations include provision of blanket
material on top of formation and extra earthwork for unstable slopes.
Consultancy Report on Rehabilitation of weak formation between Pandrasali & Rajkharswan stations, SER
1. 0 INTRODUCTION
Pandrasali to Rajkharswan is a double line section in the jurisdiction of
Chakradharpur Division of South Eastern Railway. The section lies on heavy
mineral route. The borrow pits/Ditches lie adjacent to the toe of the embankment and filled with water in one of the problematic locations between Pandrasali to Rajkharswan.
South Eastern Railway vide letter no. TC/TWF/GENL/Pt.XIII/2157 dated 30.10.07 referred this section to RDSO for investigation & suggesting remedial measures. Accordingly RDSO team visited site in the month of February 2008 to investigate and suggest remedial measures. Two most problematic weak stretches were selected as given here under:
SL Referred Location
Length Locations Selected
Between Stations
- Km.296- Km.294 2000 m Km 294/36-34(Dn.) & Km 294/64-62(Dn.)
Pandrasali & Rajkharswan
Accordingly site observations were made & soil samples were collected from these locations, which are representative of the affected section of the track as stated by Shri P.K.Rudra, AEN/Chaibasa.
2.0 REFERENCE
Chief Track Engineer vide his letter no. TC/TWF/GENL/Pt.XIII/2157 dated 30.10.07 (received on 12.12.07) requested RDSO for investigating and suggesting remedial measures.
3.0 SCOPE OF WORK
Site inspection, soil exploration, testing and recommendations for the stabilisation of unstable formation on the stretches indicated vide letter in reference (Para 2.0).
4. 0 HISTORY OF PROBLEM
The traffic density on this section has increased considerably in recent years. The ballast under the sleeper got mixed with iron ore and soil and caked, partly on account of the intensity of traffic and heavy axle loads. According to the site engineers there are number of locations where proper maintenance of track has posed problem due to bad formation. The trouble is experienced mostly during rains, when the track settles unevenly and cross-levels go out frequently. On opening the track it was found that the ballast is mostly in a caked condition. It was also found that the ballast has penetrated more than 1.6 m from top of rail. This shows that whatever extra ballast has been put into the track from time to time has been gradually disappearing into the formation as a result of puncturing into the formation.
Consultancy Report on Rehabilitation of weak formation between Pandrasali & Rajkharswan stations, SER
8.0 SITE INSPECTION AND COLLECTION OF FIELD DATA
8.1 General
The alignment between Pandrasali to Rajkharswan lies on heavy mineral route in which 25 tones axle load plies. The borrow pits/Ditches lie adjacent to the toe of the embankment and filled with water in one of the problematic locations between Pendrasali to Rajkharswan. Low cess, flattening of slope & tilting of OHE mast have also been observed. Bank slip has been reported in the past during monsoon between Pendrasali and Rajkharswan.
8.2 Km. 294/36-34 (Dn.)
In this stretch frequent variation of cross level and alignment is reported.
Borrow pits/ Ditches filled with water was found adjacent to the toe of the embankment. To maintain cross level and alignment track is lifted by ballast. Iron ore was found on the top of formation. Flattening of slope was found. Three undisturbed and one disturbed soil samples were collected, to assess the capacity to withstand dynamic loads.
8.3 Km 294/64-62 (Dn.)
In this stretch frequent variation of cross level and alignment has been reported. To maintain the alignment and cross level, the track is lifted by ballast. Flattening of slope was found. Ballast penetration was found more than 1.6 m from Rail level. One undisturbed & two disturbed soil samples were collected, to assess the capacity to withstand dynamic loads.
9.0 Analysis & Discussion of Test Results
9.1 Location - Km 294/36-
One disturbed soil sample and three undisturbed soil samples collected from this location were tested & test results are as under :
Consultancy Report on Rehabilitation of weak formation between Pandrasali & Rajkharswan stations, SER
Soil Properties –
SL Soil Parameters Sub grade Soil (UDS)
Top Formation Soil (UDS)
- Classification CH SC Grain Size Distribution :
Gravel (%) 00 16 Sand (%) 24 40 Silt (%) 49 35 Clay (%) 27 09
Fines passing 75 sieve (%) 76 44 Consistency Limits : Liquid Limit 53 40 Plastic Limit 23 15 Plasticity Index 30 25 SL 9.0 -
DFS 45.45 36.
4. NMC (%) 11.58 14.
NDD (g/cm^3 ) 1.446 1.
- C (^) u 1272.7 - C (^) c 0.17 - Shear Parameters : C (kg/cm^2 ) 0.140 0.
(degree) 23.17 29.
Soil Properties –
SL Soil Parameters Ground Soil (UDS)
Top Formation Soil (DS)
- Classification CH SC Grain Size Distribution :
Gravel (%) 00 28 Sand (%) 26 35 Silt (%) 44 33 Clay (%) 30 04
Fines passing 75 sieve (%) 74 37
Consultancy Report on Rehabilitation of weak formation between Pandrasali & Rajkharswan stations, SER
Soil Properties –
SL Soil Parameters
Ground Soil (DS)
Sub grade Soil (UDS)
Top Formation Soil (DS)
- Classification CH CH CH
- Grain Size Distribution: Gravel (%) 01 01 00 Sand (%) 07 10 36 Silt (%) 77 64 61 Clay (%) 15 25 03 Fines passing 75 sieve (%) 92 89 64 Consistency Limits : Liquid Limit 57 59 54 Plastic Limit 27 24 27 Plasticity Index 30 35 27 SL 11.00 11.00 9.
DFS 54.55 15.38 45.
4. OMC(%) 10.80 - 12.
MDD(g/cm^3 ) 1.86 - 1. NMC(%) 20.25 - NDD (g/cm^3 ) 1.428 -
- C (^) u 18.13 - 12. C (^) c 0.44 - 0.
- Shear Parameters : C (kg/cm^2 ) 0.080^ 0.129^ 0. (degree) 27.71^ 23.95^ 28.
Grain size distribution & test for consistency conducted on the collected soil samples classify the soil as CH i.e. highly compressible clay, for Ground soil, Sub-grade soil and Top formation soil. NMC of Sub-grade soil approaches to plastic limit therefore, Sub-grade soil is in plastic stage. SL and DFS value indicate that the Top formation soil is highly shrinkable and swelling in nature.
C (^) u , C (^) c value indicate that Top of Formation soil is not well graded. C’ and value has been determined for ground soil, sub-grade soil and top formation soil for slope stability analysis. Under above circumstances for CH type of soil at top, minimum 100 cm. thick compacted blanket layer is required at top of formation as per Para
- 4.3.2 and 4.3.4 of “Guidelines For Earthwork in Railway Projects”: July
- After executing the work for proposed profile, erosion control measure like turfing should be carried out.
Consultancy Report on Rehabilitation of weak formation between Pandrasali & Rajkharswan stations, SER
Photograph Showing Site View
10.0 FORMULATION OF REMEDIAL MEASURES :
The analysis and discussion of test results, as given in Para - 9 emphasise the need of providing : (i) Adequate cess width. (ii) Adequate thickness of blanket material conforming to specification given in Para - 4.3.4 of “Guidelines for earthwork in Railway projects”: July 2003.
11.0 RECOMMENDATIONS:
Following recommendations are made: General:
(i) Minimum 100 cm thick compacted blanket cushion shall be provided in the stretches having CH type of soil and 100 cm thick compacted blanket cushion shall be provided in the stretches having SC type of soil having plasticity index more than 7 after removing the loose ballast under formation, and it shall be provided in full width of formation.
(ii) 30 cm clean ballast cushion should be ensured. (iii) Minimum cess width of 900 mm should be ensured.
(iv) Bank slope shall be provided as per design given in Annexure-II & III. (v) Top of formation must have a cross slope of 1:30. (vi) Dry stone pitching 1.0 m above HFL, should be provided in flood prone area.
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Consultancy Report on Rehabilitation of weak formation between Pandrasali & Rajkharswan stations, SER
Page 12 of 18
ANNEXURE –I
Research Designs & Standards Organization^ Geo-technical Engineering Directorate of R.D.S.O.
Reporting of soil testing
Name of Project:
- Weak Formation Between Pandrasali-Rajkharswan. Chakradharpur Div, SER.
Reference No.: - RS/G/72/SER,
Date of Receiving sample -
Report No. 15/2008 (Part-I),dated 09.04.
Mechanical Analysis
(In %)
Consistency Limit
Tri-axial shear /Direct shear test
Laboratory Sample
No.05/2008/SER
Chainage (Km)
Soil Classification
As per IS Specification
Natural Moisture
Content (in %)
Natural Dry Density
(in gm/cc)
Gravel
Sand
Silt
Clay
Percentage Passing
75 micron sieve
Uniformity Coefficient
(Cu)
Coefficient of Curvature
(Cc)
Liquid Limit
(in %)
Plastic Limit
(in %)
Plasticity
Index
Shrinkage
Limit (in %)
Differential
Free Swell
(in %)
Cohesion C'
Kg/Cm²
Angle of Internal
' friction
In degree
Optimum moisture
Content (in %)
M
D
D
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
294/36-34(DN)
SC
-^
294/36-34(DN)
CH
-^
-^
-^
294/36-34(DN)
CH
-^
-^
-^
294/36-34(DN)
SC
-^
-^
-^
-^
294/64-62(DN)
CH
-^
-^
-^
294/64-62(DN)
CH
-^
-^
294/64-62(DN)
CH
-^
-^
DD/GE
SSRE/GE
Consultancy Report on Rehabilitation of weak formation between Pandrasali & Rajkharswan stations, SER
ANNEXURE-II
Pandrasali – Rajkharswan Section Chakradharpur Division, South Eastern Railway. Profile at km. : 294/36- Height of Bank: 8.16 m. Factor of Safety = 1.512 At Slope 2:1 with 2 m wide berm below 6.0 m from top
Designed Profile
Soil 1 Top Soil Soil model Mohr- Coulumb Unit Weight 18 Cohesion 5 Phi 29. Unsaturated Phi B 0 Peziometric Line # 0 Ru (added) 0. Pore Air Pressure 0
Soil 2 Sub-grade Soil Soil model Mohr- Coulumb Unit Weight 18. Cohesion 14 Phi 23. Unsaturated Phi B 0 Peziometric Line # 0 Ru (added) 0. 25 Pore Air Pressure 0
Soil 3 Ground Soil Soil model Mohr- Coulumb Unit Weight 18. Cohesion 14. Phi 22. Unsaturated Phi B 0 Peziometric Line # 0 Ru (added) 0. 5 Pore Air Pressure
Soil 4 BED ROCK Soil model Bed Rock Unit Weight - Peziometric Line # 0 Ru (added) 0
Consultancy Report on Rehabilitation of weak formation between Pandrasali & Rajkharswan stations, SER
To Kharagpur
Barajamda Jn.
Padapahar
Index Plan Showing Location Of Weak Formation On Rajkharswan-Chaibasa Section, Chakradharpur Division, South Eastern Railway NOTE:- NOT TO SCALE^ DRG. NO. GE/SK/SE/609/REV.0/
Research Designs & Standards Organisation
Chakradharpur Barabamboo
To Adra
Rajkharswan
Chaibasa
Pandrasali
Sini Jn.
Tatanagar
N
FIGURE - 1
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Consultancy Report on Rehabilitation of weak formation between Pandrasali & Rajkharswan stations, SER
Page 16 of 18
Rehabilitation Of Weak Form ation DRG. NO. GE/SK/SE/595/Rev.0/
From Km 294-296 Between Pendrasali-Rajkharswan stationson Rajkharswan-Chaibasa section,
Chakradharpur Division,South Eastern Railway
Research Designs & Standards Organisation
FIGURE - 2
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Consultancy Report on Rehabilitation of weak formation between Pandrasali & Rajkharswan stations, SER
Page 18 of 18
1 in 30
Blanket thickness as per soil classification as discussed in para 9.
EXISTING BANK PROFILE SHOWN IN BLACK. PROPOSED PROFILE IS SHOWN IN RED.
1 in 30
1 in 30
900
Rehabilitation Of Weak Formation DRG. NO. GE/SK/SE/610/Rev.0/
From Km 294-296 Between Pendrasali-Rajkharswan stationson Rajkharswan-Chaibasa section,
Chakradharpur Division,South Eastern Railway
Research Designs & Standards Organisation
1 in 30
900
FIGURE - 4
