REPORT - Earthquake Commission€¦ · Geotechnical Factual Report Southshore Prepared by Tonkin & Taylor Limited for the Earthquake Commission February 2011 Applicability This report

Darfield Earthquake Recovery Geotechnical Factual Report Southshore T&T Ref. REP-SSH-FAC

Earthquake Commission February 2011

REPORT Earthquake Commission

Darfield Earthquake Recovery Geotechnical Factual Report Southshore



REPORT

Report prepared for:

EARTHQUAKE COMMISSION

Report prepared by:

TONKIN & TAYLOR LTD

Distribution:

EARTHQUAKE COMMISSION 3 copies

TONKIN & TAYLOR LTD (FILE) 1 copy

February 2011

T&T Ref: REP-SSH-FAC

Earthquake Commission


Darfield Earthquake Recovery Geotechnical Factual Report Southshore Prepared by Tonkin & Taylor Limited for the Earthquake Commission

February 2011

Applicability This report was produced for the Earthquake Commission (EQC) to assist in assessing insurance claims made under the Earthquake Commission Act 1993. This report is not intended for any other purpose. It is recognised, however, that this report may assist central and local government planning for effective long-term solutions for the affected communities. Neither Tonkin & Taylor Ltd (T& T) nor the Earthquake Commission accepts any liability to any third party with respect to this report.

Limitations

This document is released for general information purposes only and should only be used for design purposes by appropriately qualified and experienced Scientists, Geologists and/or Professional Engineers.

All of the data and information which is contained in this document may only be used for the purposes of recovery and repair of land and building damage associated with the 04 September 2010 Darfield Earthquake.

This report comprises a main body and separate appendices which must be read in their entirety and are to be used in conjunction with each other.

Darfie ld Earthquake Recovery Geotechnical Factual Report Southshore Earthquake Commission

T&T Ref. REP-SSH-FAC February 2011



Table of contents

1 Introduction 1

2 Project background 1

3 Site description 2 3.1 General 2 3.2 Regional geology 2

4 Geotechnical investigations 2 4.1 General 2 4.2 Cone penetration testing (CPT) 2 4.3 Machine boreholes 3 4.4 Geophysical testing 3

5 Groundwater observations 3

6 Laboratory testing 3

7 Environment Canterbury information 3

8 References 4

Appendix A: Investigation Location Plans

Appendix B: Cone Penetration Testing

Appendix C: Environment Canterbury Boreholes

1



1 Introduction

The Earthquake Commission (EQC) engaged Tonkin & Taylor (T&T) to undertake site investigations around selected suburbs of Canterbury following the Darfield Earthquake sequence that started on 4 September 2010. These site investigations comprise:

a) Cone penetration testing b) Machine boreholes c) Geophysical testing d) Groundwater observations e) Laboratory testing

Site investigation works and factual reporting is being undertaken for a number of suburbs that were affected by liquefaction induced land damage.

The report contains factual data to provide a geotechnical source for council consent applications for the suburb. This report presents all currently available geotechnical and engineering geological investigations that were commissioned by EQC after the 2010 Darfield Earthquake and all readily available data that Environment Canterbury and Christchurch City Council hold for the suburb.

This is a factual report of field investigations. The field investigations have been undertaken at discrete locations and no inferences about the nature and continuity of ground conditions away from the investigations locations are made. No interpretation of investigation results has been made in this report.

2 Project background

The magnitude (M) 7.1 Darfield Earthquake occurred on 4 September 2010. The epicentre was close to the town of Darfield, approximately 40 km west of Christchurch. The earthquake caused extensive ground liquefaction, in localised areas of Canterbury. The liquefaction resulted in major ground settlement, lateral spreading and, to a lesser extent, foundation support failure, with consequential building damage.

T&T carried out a broad geotechnical land damage assessment and mapping of the main urban areas in the Canterbury region that have been significantly affected by strong ground motion arising from the earthquake. The results of that assessment are presented in the T&T Stage 1 report (Ref 1) dated October 2010 and released to the general public by EQC. The Stage 1 report presented the land damage categorisation, mapping methodology, information and results generated to 1 October 2010. Land remediation concepts and generalised land remediation options were also presented.

The T&T Stage 2 report (Ref 2) dated November 2010 and released to the general public by EQC is based on a detailed suburb-by-suburb engineering assessment into the nature and extent of land damage. It also identifies land repair strategies for each suburb and areas most affected by land damage. The report presents 22,500 mapped properties as at 5 November 2010 in Canterbury and separates them into three recovery zones; A, B and C. These recovery zones relate to the extent of land repair required and allow for a coordinated recovery plan.

2



3 Site description

3.1 General

Southshore is a suburb in the east of Christchurch and is located approximately 9 km from the Christchurch CBD (Drawing LOC-SSH-01, Appendix A) and within Christchurch City Council jurisdiction. The subject area is situated on sand dunes of the South Brighton spit east of the estuary of the Avon and Heathcote rivers. It is bounded in the east by Pegasus Bay, to the south by the estuary outlet and to the west by the estuary. The suburb is built on fixed coastal dune systems and the coast line lies immediately to the east of the suburb.

The area is low lying and topographically is typically flat.

3.2 Regional geology

Geology of the Christchurch Urban Area (Ref 3) shows the subject area to be underlain by sand of fixed and semi-fixed dunes and beach deposits of Holocene age.

4 Geotechnical investigations

4.1 General

The geotechnical investigations commissioned by EQC from September 2010 were determined and located under direction from T&T. The locations were selected taking into account access for the site investigation plant, the presence of services and any traffic management requirements. The current investigations comprise 10 cone penetration tests (CPTs).

The location of the site investigations is shown on Drawing GIP-SSH-01 (Appendix A) and the above investigation technique is discussed below.

4.2 Cone penetration testing (CPT)

Five companies were commissioned to provide CPT probing services on this project and information on the CPT rig capability is summarised briefly below. The output of each CPT rig varies and therefore the testing data has been produced on a standard T&T template. The company which carried out each CPT test is identified on the CPT log. The companies that carried out the testing were:

a) Opus International Consultants Ltd (Opus) - 18T truck-mounted rig b) Perry Drilling Ltd (Perry) - 20T rubber tracked truck-mounted rig c) McMillan Drilling Services (McMillan) - 14T truck-mounted rig d) Geotech Drilling (Geotech) - 16T truck-mounted rig e) Ground Investigations Ltd (GI) - self-augering Pagani CPT rig. The rig augers reaction

anchors into place in the ground in order to drive a standard CPTu cone with up to 20T of force.

Selected CPT probes had down-hole seismic shear wave velocity testing carried out. These are identified on each CPT log and summarised in Table 4-1 below.

Each CPT probe location was pre-dug by hand to between 800 mm and 1200 mm to mitigate the risk of unforeseen underground services being present at the selected investigation locations.

The results of the CPT probing are presented in Appendix B.

3



The CPT testing undertaken is summarised in Table 4-1.

Table 4-1 Cone penetration testing summary

CPT ID Maximum depth (m) Comments

CPT-SSH-01 11.14 Pilot CPT

CPT-SSH-02 25.97

CPT-SSH-03 26.02

CPT-SSH-04 23.58 Seismic CPT

CPT-SSH-05 22.79

CPT-SSH-06 23.25

CPT-SSH-07 28.50 Seismic CPT

CPT-SSH-08 45.11

CPT-SSH-09 17.30

CPT-SSH-10 16.32

4.3 Machine boreholes

No machine boreholes have been carried out in the suburb of Southshore.

4.4 Geophysical testing

No geophysical testing has been carried out in the suburb of Southshore.

5 Groundwater observations

In Southshore, during the investigations, groundwater depths ranged from 2.3 m to 0.9 m below existing ground level. These identified levels were based on dynamic pore water pressure results in CPT testing and field observations of waterways (rivers and sea levels).

6 Laboratory testing

No laboratory testing has been carried out for the subject area.

7 Environment Canterbury information

Additional borehole data, which is held by Environment Canterbury for the subject area, has been included in Appendix C. This data has been reproduced with the permission of Environment Canterbury and forms part of previous investigations undertaken by a variety of geotechnical consultants. Records for boreholes outside of the area covered by this report may be obtained from Environment Canterbury.

4



8 References

1. Tonkin & Taylor Ltd (October 2010), prepared for the Earthquake Commission Darfield Earthquake 4 September 2010 Geotechnical Land Damage Assessment & Reinstatement Report STAGE 1 REPORT.

2. Tonkin & Taylor Ltd (November 2010), prepared for the Earthquake Commission Darfield Earthquake 4 September 2010 Geotechnical Land Damage Assessment & Reinstatement Report STAGE 2 REPORT.

3. Brown, L.J.; Weeber, J.H. (1992), Geology of the Christchurch urban area. Institute of Geological & Nuclear Sciences 1:25,000 geological map 1. 1 sheet + 104p. Lower Hutt, New Zealand, Institute of Geological and Nuclear Sciences Limited.

5




Darfield Earthquake Recovery Geotechnical Factual Report Southshore Appendix A: Investigation Location Plans

Darfield Earthquake Recovery Geotechnical Factual Report SouthshoreSouthshore

Appendix A: Investigation Location Plans T&T Ref. REP-SSH-FAC


REPORT



Report prepared by:

Tonkin & Taylor LTD

Distribution:


Tonkin & Taylor LTD (FILE) 1 copy

February 2011



Darfield Earthquake Recovery Geotechnical Factual Report Southshore Appendix A: Investigation Location Plans




Appendix A: Investigation Location Plans

SOUTHSHORE

Environmental and Engineering Consultants

Tonkin & TaylorLevel 6, 151 Kilmore St, Christchurch

Tel. (03) 363-2440 Fax. (03) 363-2441www.tonkin.co.nz

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Environmental and Engineering Consultants

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Earthquake Commission January 2011


Darfield Earthquake Recovery Geotechnical Factual Report Southshore Appendix B: Cone Penetration Testing


Appendix B: Cone Penetration Testing T&T Ref. REP-SSH-FAC


REPORT



Report prepared by:

TONKIN & TAYLOR LTD

Distribution:



February 2011



Darfield Earthquake Recovery Geotechnical Factual Report Southshore Appendix B: Cone Penetration Testing




Appendix B: Cone Penetration Testing

Summary Sheet – Southshore SSH 20

CPT ID Maximum depth (m)

Location (mE)

Location (mN)

Ground Surface R.L

Comments

CPT-SSH-01 11.14 2489579.02 5739454.11 1.90 Pilot CPT

CPT-SSH-02 25.97 2489739.07 5738929.22 2.00

CPT-SSH-03 26.02 2489694.10 5739016.79 1.86

CPT-SSH-04 23.58 2489797.82 5739037.08 1.73 Seismic CPT

CPT-SSH-05 22.79 2489723.23 5739372.39 1.73

CPT-SSH-06 23.25 2489735.62 5739500.19 1.66

CPT-SSH-07 28.50 2489492.49 5739775.09 1.73 Seismic CPT

CPT-SSH-08 45.11 2489347.34 5740118.43 1.81

CPT-SSH-09 17.30 2489215.91 5740476.65 1.84

CPT-SSH-10 16.32 2489116.91 5740865.48 1.60

Project: Darfield 2010 Earthquake - EQC Ground Investigations Page: 1 of 1 CPT-SSH-01 Test Date: 7-Oct-2010 Location: Southshore Operator: Geotech

Pre-Drill: 0m Assumed GWL: 2.1mBGL Located By: Survey GPS

Position: 2489579.1mE 5739454.1mN 1.795mRL Coord. System: NZMG & MSL

Other Tests: Comments:

0

2

4

6

8

10

12

14

16

18

20

0 40 80 120 160 200 240 280 320 360 400

0

2

4

6

8

10

12

14

16

18

20

0 2 4 6 8 10 12 14 16 18 20

Sleeve Friction (kPa)

Dep

th(

m)

Cone Resistance (MPa)Cone Sleeve

0 1 2 3 4 5 6

0 1 2 3 4 5 6

Friction Ratio (%)

0 100 200 300

0 100 200 300

Pore Pressure (kPa)

T+T Ref: 51731.001 Printed: 16/12/2010 4:24 p.m. Template: CPT Graph Template v0.41.xls

Project: Darfield 2010 Earthquake - EQC Ground Investigations Page: 1 of 2 CPT-SSH-02 Test Date: 26-Nov-2010 Location: Southshore Operator: Perry

Pre-Drill: 1.2m Assumed GWL: 2mBGL Located By: Survey GPS

Position: 2489739.1mE 5738929.2mN 2mRL Coord. System: NZMG & MSL


0

2

4

6

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12

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18

20

0 40 80 120 160 200 240 280 320 360 400

0

2

4

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20

0 2 4 6 8 10 12 14 16 18 20


Dep

th(

m)


0 1 2 3 4 5 6

0 1 2 3 4 5 6

Friction Ratio (%)

0 100 200 300

0 100 200 300

Pore Pressure (kPa)

T+T Ref: 51731.001 Printed: 14/01/2011 11:11 a.m. Template: CPT Graph Template v0.41.xls



Position: 2489739.1mE 5738929.2mN 2mRL Coord. System: NZMG & MSL


20

22

24

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32

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40

0 40 80 120 160 200 240 280 320 360 400

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40

0 2 4 6 8 10 12 14 16 18 20


Dep

th(

m)


0 1 2 3 4 5 6

0 1 2 3 4 5 6

Friction Ratio (%)

0 100 200 300

0 100 200 300

Pore Pressure (kPa)



Pre-Drill: 1.2m Assumed GWL: 1.2mBGL Located By: Survey GPS



0

2

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6

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10

12

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20

0 40 80 120 160 200 240 280 320 360 400

0

2

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16

18

20

0 2 4 6 8 10 12 14 16 18 20


Dep

th(

m)


0 1 2 3 4 5 6

0 1 2 3 4 5 6

Friction Ratio (%)

0 100 200 300

0 100 200 300

Pore Pressure (kPa)






20

22

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36

38

40

0 40 80 120 160 200 240 280 320 360 400

20

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40

0 2 4 6 8 10 12 14 16 18 20


Dep

th(

m)


0 1 2 3 4 5 6

0 1 2 3 4 5 6

Friction Ratio (%)

0 100 200 300

0 100 200 300

Pore Pressure (kPa)


Project: Darfield 2010 Earthquake - EQC Ground Investigations Page: 1 of 2 CPT-SSH-04 Test Date: 26-Nov-2010 Location: Southshore Operator: Opus



Other Tests: Seismic downhole Comments:

0

2

4

6

8

10

12

14

16

18

20

0 40 80 120 160 200 240 280 320 360 400

0

2

4

6

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10

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16

18

20

0 2 4 6 8 10 12 14 16 18 20


Dep

th(

m)


0 1 2 3 4 5 6

0 1 2 3 4 5 6

Friction Ratio (%)

0 100 200 300

0 100 200 300

Pore Pressure (kPa)






20

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0 40 80 120 160 200 240 280 320 360 400

20

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40

0 2 4 6 8 10 12 14 16 18 20


Dep

th(

m)


0 1 2 3 4 5 6

0 1 2 3 4 5 6

Friction Ratio (%)

0 100 200 300

0 100 200 300

Pore Pressure (kPa)






0

2

4

6

8

10

12

14

16

18

20

0 40 80 120 160 200 240 280 320 360 400

0

2

4

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8

10

12

14

16

18

20

0 2 4 6 8 10 12 14 16 18 20


Dep

th(

m)


0 1 2 3 4 5 6

0 1 2 3 4 5 6

Friction Ratio (%)

0 100 200 300

0 100 200 300

Pore Pressure (kPa)






20

22

24

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30

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40

0 40 80 120 160 200 240 280 320 360 400

20

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38

40

0 2 4 6 8 10 12 14 16 18 20


Dep

th(

m)


0 1 2 3 4 5 6

0 1 2 3 4 5 6

Friction Ratio (%)

0 100 200 300

0 100 200 300

Pore Pressure (kPa)






0

2

4

6

8

10

12

14

16

18

20

0 40 80 120 160 200 240 280 320 360 400

0

2

4

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10

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16

18

20

0 2 4 6 8 10 12 14 16 18 20


Dep

th(

m)


0 1 2 3 4 5 6

0 1 2 3 4 5 6

Friction Ratio (%)

0 100 200 300

0 100 200 300

Pore Pressure (kPa)






20

22

24

26

28

30

32

34

36

38

40

0 40 80 120 160 200 240 280 320 360 400

20

22

24

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36

38

40

0 2 4 6 8 10 12 14 16 18 20


Dep

th(

m)


0 1 2 3 4 5 6

0 1 2 3 4 5 6

Friction Ratio (%)

0 100 200 300

0 100 200 300

Pore Pressure (kPa)






0

2

4

6

8

10

12

14

16

18

20

0 40 80 120 160 200 240 280 320 360 400

0

2

4

6

8

10

12

14

16

18

20

0 2 4 6 8 10 12 14 16 18 20


Dep

th(

m)


0 1 2 3 4 5 6

0 1 2 3 4 5 6

Friction Ratio (%)

0 100 200 300

0 100 200 300

Pore Pressure (kPa)






20

22

24

26

28

30

32

34

36

38

40

0 40 80 120 160 200 240 280 320 360 400

20

22

24

26

28

30

32

34

36

38

40

0 2 4 6 8 10 12 14 16 18 20


Dep

th(

m)


0 1 2 3 4 5 6

0 1 2 3 4 5 6

Friction Ratio (%)

0 100 200 300

0 100 200 300

Pore Pressure (kPa)


Project: Darfield 2010 Earthquake - EQC Ground Investigations Page: 1 of 3 CPT-SSH-08 Test Date: 2-Dec-2010 Location: Southshore Operator: Perry




0

2

4

6

8

10

12

14

16

18

20

0 40 80 120 160 200 240 280 320 360 400

0

2

4

6

8

10

12

14

16

18

20

0 2 4 6 8 10 12 14 16 18 20


Dep

th(

m)


0 1 2 3 4 5 6

0 1 2 3 4 5 6

Friction Ratio (%)

0 100 200 300

0 100 200 300

Pore Pressure (kPa)






20

22

24

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28

30

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34

36

38

40

0 40 80 120 160 200 240 280 320 360 400

20

22

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28

30

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34

36

38

40

0 2 4 6 8 10 12 14 16 18 20


Dep

th(

m)


0 1 2 3 4 5 6

0 1 2 3 4 5 6

Friction Ratio (%)

0 100 200 300

0 100 200 300

Pore Pressure (kPa)






40

42

44

46

48

50

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54

56

58

60

0 40 80 120 160 200 240 280 320 360 400

40

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58

60

0 2 4 6 8 10 12 14 16 18 20


Dep

th(

m)


0 1 2 3 4 5 6

0 1 2 3 4 5 6

Friction Ratio (%)

0 100 200 300

0 100 200 300

Pore Pressure (kPa)


Project: Darfield 2010 Earthquake - EQC Ground Investigations Page: 1 of 1 CPT-SSH-09 Test Date: 27-Nov-2010 Location: Southshore Operator: McMillan




0

2

4

6

8

10

12

14

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18

20

0 40 80 120 160 200 240 280 320 360 400

0

2

4

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8

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12

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16

18

20

0 2 4 6 8 10 12 14 16 18 20


Dep

th(

m)


0 1 2 3 4 5 6

0 1 2 3 4 5 6

Friction Ratio (%)

0 100 200 300

0 100 200 300

Pore Pressure (kPa)


Project: Darfield 2010 Earthquake - EQC Ground Investigations Page: 1 of 1 CPT-SSH-10 Test Date: 27-Nov-2010 Location: Southshore Operator: McMillan




0

2

4

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12

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20

0 40 80 120 160 200 240 280 320 360 400

0

2

4

6

8

10

12

14

16

18

20

0 2 4 6 8 10 12 14 16 18 20


Dep

th(

m)


0 1 2 3 4 5 6

0 1 2 3 4 5 6

Friction Ratio (%)

0 100 200 300

0 100 200 300

Pore Pressure (kPa)






Appendix C: Environment Canterbury Boreholes T&T Ref: REP-SSH-FAC



Darfield Earthquake Recovery Geotechnical Factual Report Southshore Appendix C: Environment Canterbury Boreholes




REPORT



Report prepared by:

TONKIN & TAYLOR LTD

Distribution:



February 2011



Darfield Earthquake Recovery Geotechnical Factual Report Southshore Appendix C: Environment Canterbury Boreholes




Appendix C: Environment Canterbury Boreholes

Borehole ID Maximum depth (m) Location (mE) Location (mN) Ground level R.L

M36/5893 54.30 2489642.00 5739908.00 2.15

M36/5894 84.70 2489649.00 5739892.00 2.15

M36/5895 138.00 2489655.00 5739877.00 2.15

M36/8868 8.53 2489519.00 5739864.00 1.82







Documents

REPORT - Earthquake Commission€¦ · Geotechnical Factual Report Southshore Prepared by Tonkin & Taylor Limited for the Earthquake Commission February 2011 Applicability This report