Geotechnical Report 02 Revised

8/10/2019 Geotechnical Report 02 Revised

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GROUP:

Final Geotechnical Exploration and

Evaluation Report

Gymnastic and Meeting Building

Florida

Date:- _____________

Prepared For

The Parks and Recreation Department of Relax City, Florida


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The Parks & Recreation Department, Our Ref:

Relax City, Date:

Florida

Attn: The Manager

SUB: Final Geotechnical Exploration and Evaluation Report of Gymnastic and

Meeting Building, Near City Hall, Florida

Dear Sir,

We have the pleasure to submit our site investigation report on your proposed project at the

above site. This report includes field and laboratory test results in addition to our conclusions

and recommendations for design and type of foundation

We are happy to render our services upon your request and would like to thank you for your

confidence. Please do not hesitate to call on us for any assistance whenever needed.

Yours Faithfully,

(Student Name)


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Table of Contents

1. INTRODUCTION 3

2. PURPOSE OF INVESTIGATION 3

3. SCOPE OF WORK 3

4. SITE DESCRIPTION 3

5. SUBSOIL CONDITIONS AND DESCRIPTION 4

6. FIELD TEST 4

7. DISCUSSION 5

8. FOUNDATION DESIGN CONSIDERATION 5

10. SUMMARY OF RECOMMENDATIONS 8

11. APPENDIX 8


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1. INTRODUCTION

This report presents the field work and test results of geotechnical investigation of the proposed

site with the following information.

Client : The Parks and Recreation Department of Relax City Site area : 4,877 m

2

Project : Gymnastic and Meeting Building

Location : Florida

Height of building : 13.7 m

2. PURPOSE OF INVESTIGATION

The main purpose of this study is to determine the surface and subsurface conditions at the

proposed site and to define physical and mechanical properties of the foundation materials inaddition to specifying other engineering characteristics of the encountered strata. This is in

order to guide the designer to achieve an adequate and economic design of the foundation type,

shape and size.

3. SCOPE OF WORK

Geotechnical Investigation was made at the proposed site by drilling 05 (five) boreholes

numbered as given in the borehole location plan given in figure 01. The location of the site is

given on Location Plan.

Boreholes of 50 mm diameter were drilled down to 7.62 m from, the respective borehole levels,

using 63.5 kg weight. Drilling in soils was carried out by the Cable Tool Percussion method.

Sampling and subsequent laboratory testing were used to classify various soil strata.

Fieldwork was commenced on 16/03/2009 and was completed on 16/03/2009.

4. SITE DESCRIPTION

The proposed site covers an area of 4877 sq. meter. It is bordered three sides from buildings and

in front with existing roads. At the time of investigation, the site was highly undulating and was

vacant. There were not such differences among the ground levels at certain locations.


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5. SUBSOIL CONDITIONS AND DESCRIPTION

The nature of subsurface as encountered by borehole drilling, described in accordance with

ASTM, is summarized below. A section through boreholes is presented on the borehole

correlation chart in appendix B figure 03 to 07.

Depth

Range (m)"N" Range Description

0.03 12-45 Brown silica sand with fragmented limestone

37 14 - 45 Fragmented limestone

Stratum # 1:In general the top stratum starts off below a thick cover of dense dark brown silica

sand consisting of sand mixed with fragmented limestone. The soil can in general be classified

as SP.

Stratum # 2: This stratum underlying stratum # 2 consists of tan fragmented limestone and

extends to the final depth explored. In borehole No 01 & 03, again tan sand with fragmented

limestone of depth 1.5 m is encountered. This stratum is rock and exists in a soft to medium

dense condition of compactness with SPT value ranging 14 to 40.

Groundwater: Ground water was encountered at depths ranging from 1.98-2.1 m below the

investigated ground level. Measurements of ground water levels were taken on the day

following the completion of fieldwork-

6. FIELD TEST

6.1. STANDARD FENETRATION TESTS

Standard penetration tests (SPT's) were conducted regularly at 15 cm intervals up to the

investigated depth in accordance with the drilling procedure specified in ASTM D-1586.

The test was carried out using a manual drop hammer assembly, which utilizes a manual trip

mechanism to release the weight all in accordance with ASTM D-1586. Results are presented

on borehole logs appendix B figure 03 to figure 09.


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7. DISCUSSION

The proposed construction is Gymnastic and Meeting Building with approximate 13.7 m height.

Based on the type of structure and the soil conditions encountered, shallow foundations are

recommended.

The level survey reveals the following points;

The site was not so undulating and there were no significant differences among the existing

ground levels at certain locations as the ground levels.

There were zero differences of among the borehole levels as their levels of all the bore holes

depth are 7.62 m.

At the time of investigation, the following facts were observed:

In one of the boreholes drilled, the subsoil strata show presence of loose to medium dense

silica sand and gray concrete fill layers up to 0.61m below the investigated ground level.

These SPT values are coming within the load influence zone of shallow foundations and

limiting the bearing pressure values (which are evaluated based on both shear and settlement

criteria).

The ground water table was encountered at depths ranging from 1.98~2.1 m below the

investigated ground level.

8. FOUNDATION DESIGN CONSIDERATION

8.1. ALLOWABLE BEARING CAPACITY

There are many methods to calculate the allowable bearing pressures of the soil and there are

considerable variations in the values obtained by different methods and hence it is practically

impossible to fix a single value for a particular site for a given breadth and type of foundations

even after considering the same magnitude for factor of safety. This is because of the many

uncertainties in determining the allowable bearing pressure values. Based on our experience we

may be assigning different values for factor of safety for different areas and this will be a

minimum of 3.0 for shallow foundations.


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Meyerhof Bearing Capacity Theory Based on Standard Penetration Test Values

Qu= 31.417(NB + ND) (kN/m2) (metric)

For footing widths of 1.2 meters or less

Qa= 11,970N (kN/m

2

) (metric)

For footing widths of 3 meters or more

Qa= 9,576N (kN/m2) (metric)

Where:

N = N value derived from Standard Penetration Test (SPT)

D = depth of footing (m) (ft), and

B = width of footing (m) (ft).

Taking into consideration the above described criteria the net allowable bearing pressure has

been calculated at 1 m depth below the existing ground surface. The recommended allowable

bearing pressure values in general are as follows:

Depth of

Foundation

Type of

Foundation

Least lateral

Dimension of

Foundation

Net Allowable

Bearing

Pressure

1 m Shallow Square 1.25 m 565 kN/m

The actual net bearing pressure value for any particular Isolated Square foundation can be seen

from Table 02.

9. ENGINEERING RECOMMENDATIONS

9.1. SHALLOW FOUNDATIONS CONSIDERING GROUND IMPROVEMENTS

The following lines shall be considered prior to placing shallow foundations:
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Excavate the construction area up to a level 1 m and compact the excavated surface to not less

than 95% of the maximum dry density of the soil using a heavy vibratory roller.

Compaction tests shall be carried out for each compacted layer to confirm the

aforementioned percentages of compaction. Since excavation exceeds 1 m below the natural ground level, suitable side protection has to

be ensured during excavations, ground improvements and foundation placement works.

Since the ground water table was encountered at levels 2.1 m, dewatering may not be

necessary to be carried out to below the aforementioned excavation level.

Based on the above, allowable bearing pressures as given in table may be used for isolated

square footings of width 1.25 m, at 1 m above excavated and backfill compacted level.

Depth of

Foundation

Type of

Foundation

Least lateral

Dimension of

Foundation

Net Allowable

Bearing

Pressure


These allowable bearing pressures are obtained using Meyerhof bearing capacity theory based

on "Estimating allowable bearing pressure for foundations in sand on basis of results of standard

penetration tests" and incorporates a factor of safety of at least 3 on the-ultimate bearing

pressure assuming ground water to rise to foundation level.

9.2. CONSTRUCTIONAL ASPECTS

We recommend the following measures for long-term stability of the structures.

As mentioned in the report the boreholes made were of 50.8 mm in diameter. The

information received from the limited number and the stipulated diameter of boreholes may

not represent the entire site and may not reveal all the weak layers or conditions especially

when they are localized. Hence no responsibilities can be born for conditions not revealed

by boreholes or trial pits made on the site. In case of any such findings we shall be contacted

immediately to arrange a site visit by our engineer to make an on-site study of such

conditions after which recommendations if it is deemed necessary will be revised.


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In case ground improvements are necessary to be carried out, techniques suitable for any

particular site shall be selected in consultation with geotechnical engineer.

In case of any hard strata like the sandstone, siltstone or other rock types, use of special

excavators for excavations of such strata shall be considered.

Prior to providing foundation concrete, the foundation soil after excavation may be

thoroughly compacted before placing foundation concrete.

9.3. INSPECTION AND MONITORING

It is necessary that all the geotechnical aspects of foundation construction and earthwork be

monitored by competent construction supervision staff including qualified and experienced

engineers. For this purpose a comprehensive inspection and monitoring program should be

prepared.

10.SUMMARY OF RECOMMENDATIONS

10.1. TYPE OF FOUNDATION

Shallow foundation Isolated Square type with size 1.25 m x 1.25 m is selected and drawing is

attached

10.2. MINIMUM DEPTH OF FOUNDATION

Minimum depth of foundation should be 1 m below the existing ground level on well

compacted soil.

10.3. BEARING PRESSURE

The recommended allowable bearing pressure values in general are as follows:

Depth of

Foundation

Type of

Foundation

Least lateral

Dimension of

Foundation

Net Allowable

Bearing

Pressure


11.APPENDIX

Tables

Bore Hole Logs figures


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APPENDIX - A

TABLE-1

Empirical Values For , Qu, Drand Unit Weight Of Soils Based on The SPT

Soil Properties at depth 3 ft

Relative Density, Dr= 0.56

Standard Penetration Test value, N = 24

Approximate angle of internal friction, (degree) = 33.5

Approximate range of moist unit weight, y (pcf) = 124 Ib/ft3=1986 kg/m3

Submerged unit weight, sub= 67


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Table-2

Calculation of Foundation Width

Let

B = 1.25 mD = 1 m

Meyerhof Bearing Capacity Theory Based on Standard Penetration Test Values

Qu= 31.417(NB + ND) (kN/m2) ------------(1) (metric)

Thus,

Qu= 31.417((24)(1.25) + (24)(1)) = 1696 kN/m2

Qa= QU =565 kN/m2 ----------(2)

F.S

Qa= 565 kN/m2

As column load for 1.25 m x 1.25 m square footing is 800 kN (180,000 lb) and stress applied is

800/1.62= 512 kN/m

2,thus Qa >565 lb/ft

2


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APPENDIX - B

Figure -01


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LEGENDS

Figure -02


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Figure -04


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Figure -05


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Figure -06


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Figure -07


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Fig

ure-08


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Figure-09

Documents

Geotechnical Report 02 Revised