Occurrence and Uses Of Carbon

Applications Of Geology In Engineering ConstructionDayarathne G.R.I.SS/09/213There are three major rock types that cover the earth crust.Igneous RocksSedimentary RocksMetamorphic RocksThese are different from each other by there origin texture composition and mineralogy.

Introduction Most part of the Sri Lanka consists of pre-cambrian metamorphic rocks.North and North West costal plains are covered by horizontal Miocene limestone deposits and Pleistocene to recent deposits.Sri Lankan metamorphic terrain is divided into four complexes.Highland complex(HC)Vijayan complex(VC)Wanni complex(WC)Kadugannawa complex(KC)

Geology Of Sri Lanka

Fig:01:-Geological map of SL Introduction To Geo Engineering (Pvt) Ltd

Geo technical activities in Sri Lanka got a higher demand after the past war period followed by the rapid acceleration in the construction industry. As a result, drilling and other related activities are undertaken by a large number of state and private drilling and consulting companies functioning in the field of Geotechnical Engineering. Geo Engineering Consultants (Pvt) Ltd is one of the diversely skilled geo technical consultant company. which is young and active geo technical service provider operating throughout the Sri Lanka and many experienced and hard working professional geo technical consultants working with the company to ensure quality and reliability of their service.

Introduction To Geo Engineering (Pvt) Ltd Main objectives of this detailed geological and geotechnical investigation was to find out additional information and parameters regarding soil profile, rock mass quality and bed rock structure, or geological regime of the site required prior to the design and construction of the proposed structures and can be elaborated further as follows,1. To study the Geological background and sub soil material with a view to understand the subsurface conditions to identify, assess and determine the engineering geological aspects of the subsurface2. To determine and performance necessary field and laboratory tests to classify soil and rock, and evaluate their various characteristics to enable safe and economic design of the proposed structures. 3. To provide recommendations based on the field and laboratory test results, which can be used for foundation design work to come out with safe and most economical foundation type and foundation level.

OBJECTIVES OF THE INVESTIGATION

Geo Engineering Investigations

Performed by geotechnical engineers or engineering geologists.Obtain information on the physical properties of soil and rock around site. Design earthworks and foundations for proposed structures . Include surface exploration and subsurface exploration of a site.Projects typically include dams, pumping and power plants ,highways, railways, bridges, aqueducts, tunnels and levees.Subsurface exploration usually involves.Drilling .Seismicity studies.Grouting estimates .Soil sampling.Laboratory tests of the soil samples retrieved.

Field testDrilling in sand and clays to hard strata.Drilling in weathered and hard rock.Conducting standard penetration test (SPT).Collecting U.D. sample.Laboratory test.Seive analysis.Aternberg limit.Moisture content.Dry density and wet density.Hydrometer test.Proctor compaction testFIELD TEST Standard Penetration Test

Figure 1: SPT Test equipments.

Test Procedure The test uses a thick-walled sample tube, with an outside diameter of 50 mm and an inside diameter of 35 mm, and a length of around 650 mm. This is driven into the ground at the bottom of a borehole by blows from a slide hammer with a weight of 63.5 kg (140 lb) falling through a distance of 760 mm. The sample tube is driven 150 mm into the ground and then the number of blows needed for the tube to penetrate each 150 mm (6 in) up to a depth of 450 mm (18 in) is recorded.The sum of the number of blows required for the second and third 6 in. of penetration is termed the "standard penetration resistance" or the "N-value". In cases where 50 blows are insufficient to advance it through a 150 mm (6 in) interval the penetration after 50 blows is recorded. The blow count provides an indication of the density of the ground, and it is used in many empirical geotechnical engineering formulae BOREHOLESBorehole locations were given by the client. Drilling of boreholes with 76mm diameter in overburden (NX) was done by rotary boring and samples were collected in overburden for visual classification and for detailed laboratory tests. As a result 54mm core samples were yielded. After checking by a representatives of the client, termination of boreholes were decided by him. All core boxes were submitted to the Client after completion and inspection by the Client. Piezometers were installed in selected boreholes to different drilled depths as requested by the Client.Done with either tungsten carbide or diamond core bits .Use a double or triple tube core barrel when sampling weathered or fractured rock.

Fig03; Drilling Equipments with cross sectionCORE BOXES

Fig04;Images of boreholes.

Figure 05: Ruwanpura Expressway Drill site of Horana .

Field Experiences

Figure 06: Ruwanpura Expressway Drill site of Ingiriya.

Figure 10: Box sample site of Ruwanpura Highway project Ingiriya.Soil nailing is an earth retention technique using grouted tension-resisting steel elements (nails) that can be design for permanent or temporary support.The walls are generally constructed from the top down. Typically, 3 to 6 feet of soil is excavated from the top of the planned excavation. Near-horizontal holes are drilled into the exposed face at typically 3 to 6 foot centersTension-resisting steel bars are inserted into the holes and grouted. A drainage system is installed on the exposed face, followed by the application of reinforced shotcrete facing.Soil Nailing

Fig 11; Soil Nailing site during construction

Fig 12; Soil Nailing site during construction

Suggestions

Experienced Gathered through Industrial placement, as a engineering geologist and trainee site manager some problems were noticed that needs the attention of authorities.Communication between high and low level management is at very poor stage. it is recommended that at least have a one meeting for a month and give opportunities to middle and low level management to express their ideas with higher authorities.As a geologist I noticed that there are lot of petrological data available to update geological maps. Unfortunately that is not happening yet.Cooray,P.G.,1994.The Precambrian of Sri Lanka:A historical review.Precam.Res,66:3-18Das, B. M. (2006). Principles of geotechnical engineering. Stamford,CT: Thomson Learning College. Sowers, 1979. Introductory Soil Mechanics and Foundations: Geotechnical Engineering, 4th Ed., Macmillan, New York. (as referenced in Coduto, 1999. Geotechnical Engineering: Principals and Practices. Prentice Hall. New Jersey.)

REFERENCESThank You