Soil Test for Hospital Building

7/26/2019 Soil Test for Hospital Building

1/8

GEO TECHNICAL INVESTIGATION REPORT FOR THE PROPOSED

HOSPITAL BUILDING AT POTHIREDDYPALLY (V), SANGAREDDY,

MEDAK DT., TELANGANA STATE

1. INTRODUCTION

Dr Anand Naik is proposing to construct a Hospital Building at Tirumala Enclave in

Pothireddypally (V), Sangareddy (M), Medak Dt in Telangana State.

Fig. 1 gives the site plan.

The aim of this Report is to determine the depth of foundations and the safe bearing

capacity, based on Field and Laboratory Investigations

2. SCOPE OF WORK

The geo technical Investigation job was awarded to M/s Geo Explorations,

Hyderabad. The scope of the work is as follows :

i) To drill four (4 ) Bore holes at specified locations as shown in Fig.1.

ii) Collection of Samples from the Bore holes at significant depths

iii) Conduct SPT as per IS : 2131 in the Bore holes

iv) To conduct Laboratory Testing for relevant engineering properties

v) To prepare a Technical report incorporating Field and Lab test results,

recommending the foundations and SBC.

All sub soil investigations are carried out in accordance with the following BIS (IS

Codes).

IS : 1892 .. Code of investigations for Subsurface Investigations

IS : 2131 Method for Standard Penetration Test for soils

Other applicable IS (BIS) Codes are listed in Appendix

.


2/8

3. FIELD INVESTIGATIONS

a) BORE HOLES :

The bore holes were planned so as to yield complete information in the effective and

critical zones under the foundations.

The following relevant data was recorded during drilling operations.

Nature of strata Details of samples

Rate of drilling Colour of water

The bore holes were drilled to a depth of 6.0 m each below the existing GL.

b) SPT :

In addition, Standard Penetration Tests were conducted in the Bore holes, as per

with IS : 2131. In this test, a standard weight is dropped through a specified height

for a penetration of 300 m The number of blows is designated as N. According to the

Code, if N exceeds 50, refusal is said to be reached, and further drilling is

discontinued

4. LABORATORY TESTING

The soil samples were tested at the Geotechnical Engineering laboratory at

Hyderabad. The following tests were performed on soil samples:

a) Densityb) Natural Moisture contentc)Specific gravityd)Particle size analysis ( Sieve & Hydrometer )e)Atterberg Limitsf)Shear tests

All the relevant tests were conducted as per IS : 2720.

A brief description of various Tests is given below :


3/8

a) Specific gravity :

In this test as per IS : 2720-3, small quantity of the sample is tested using Specific

gravity bottle . Weights are obtained with and without water, and Specific Gravity

(G) is calculated. Low G indicates the presence of chalky components.

b) Bulk Density :

The test is conducted as per IS : 2720- 29. The weight and volume of the sample

give the bulk density.

c) Moisture content :

The test is conducted as per Is : 2720 -4. Weights of the wet sample and dry smple (

after oven- drying ) are determined to evaluate the moisture content.

d) Grain size analysis :

The test is conducted as per Is : 2720 -4. In this test, Sieves are used to separate

different sizes of coarse grained particles into gravel, sand and fines.

Hydrometer is used the differentiate silt and clay size particles.

e) Shear Test :

Direct shear test is conducted as per IS : 2720-13. A block of sample is tested in

shear to determine the friction and cohesion parameters of the soil.

5. RESULTS

Fig. 2 gives the Summary of Bore Logs. The strata details, depth wise, are

given.

Table 1 gives the soil properties.


4/8

6. FOUNDATIONS

Following is the generalized profile of sub soil.:

Depth below GL Strata N value

0 -1.5 m Silt

1.5 3 m Silty gravel 13 - 24

3 6 m SDR >50 Refusal

No water is seen in the BH ,

The soft disintegrated rock is weathered and fissured, and is relatively soft.

Significant portions of the rock show discoloration and weathering effects. The rock

has dull sound under hammer, and shows significant loss of strength as compared

with fresh rock. The degree of weath ering may be termed moderate.

Open foundations are recommended.

Appendix gives the calculations for SBC.

7. RECOMMENDATIONS :

Based on Field Investigations and Laboratory Tests, following recommendations are

given for the proposed Hospital Building at Tirumala Enclave in Pothireddypally (V),

Sangareddy (M), Medak Dt in Telangana State.

The recommendations are based on (4) Bore holes of depth 6 m each.

a) Following is the generalized profile of the site :


5/8

Depth below GL Strata N value

0 -1.5 m Silt

1.5 3 m Silty gravel 13 - 24

3 6 m SDR >50 Refusal

No water is seen in the BH ,

b) Open foundations ( Footings) are recommended.

c) It is understood that there will be a Cellar for the Building. Accordingly, SBC for

Open foundations is recommended as follows :

Depth of foundation

below cellar level

Resting in Strata Recommended SBC

1 m SDR 40 t / sq m

d) The actual size of the foundations will be based on the loads from the

superstructure.

For GEO EXPLORATIONS

Pramod Nair

Consulting Geologist


6/8

TABLE 1 :

SUMMARY OF SOIL PROPERTIES

HOSPITAL BUILDING AT POTHIREDDYPALLY (V)SANGAREDDY, MEDAK DT., TELANGANA STATE

BH No.Depth

, mSoil Moistur

econtent

%

Specific

Gravity

Grain size,percentage

KN/

Cum

ShearParameters

Gr

>4.75mm

Sa

4.75to

0.075mm

Si

.075to

.002mm

Cl


7/8

Appendix :

Calculation of SBC

HOSPITAL BUILDING AT POTHIREDDYPALLY (V)SANGAREDDY, MEDAK DT., TELANGANA STATE

FOUNDATIONS RESTING IN SDR ( Based on N Value)

a) Shear Criterio n :

Assumed value of N = 50

Assumed width of foundation =2 m

Assumed depth of foundation = 1 m inside SDR

Correction factors Rq = Rr = 0.5

With a F.S. of 3 ,

Allowable q = 1 / 18 [ 2 N 2 B Rr + 6 ( 100 + N 2 ) D Rq ] = 711 kN / sq m

b) Set t lement Cr i ter ion :

For permissible settlement of 40 mm,

Allowable Bearing Pressure = 12.25 N ( B + 0.3) / B

= 704 kN / sq m

Adopt 400 kN / sq m .

c) As p er IS : 8009 ( Fig . 2 ) Code of Pract ice for ca lcula t ion of s e t t lements o f

founda t ions :

For N = 50, B = 2 m ,

Settlement = 0.0048 m per unit pressure of 1 kg / sq cm


8/8

For a pressure of 40 t/ sq m,

Settlement = 0.004 x 4.8 x1000 = 19.2 mm OK

d) As p er IS : 12070 ( Code of Pract ice for Design & Con struct io n of Shal low

Founda t ions on Rocks ) :

Weathered and disintegrated rock is treated under Classification No. V of

Table 3 of the Code

For this very poor rock , net allowable bearing pressure is recommended as

45 t / sq m , for settlement less than 12 mm.

Keeping the above considerations in view, Recommended Safe Bearing

Capacity is 40 t per sq m

Documents

Soil Test for Hospital Building