CERS - 2015Civil Engineering Research Symposium 2015http://dl.lib.uom.lk/handle/123/177782024-03-28T16:16:21Z2024-03-28T16:16:21ZCivil Engineering Research Symposium 2015 (Pre Text)http://dl.lib.uom.lk/handle/123/204392023-10-13T02:31:38Z2015-01-01T00:00:00ZCivil Engineering Research Symposium 2015 (Pre Text)
Hettiarachchi, MTP
2015-01-01T00:00:00ZEffect of construction sequence on the behaviour of gravity type retaining wallSanjei, CDe Silva, LINhttp://dl.lib.uom.lk/handle/123/179032022-10-12T02:44:14Z2015-10-01T00:00:00ZEffect of construction sequence on the behaviour of gravity type retaining wall
Sanjei, C; De Silva, LIN
Hettiarachchi, MTP
Gravity retaining walls derive their capacity to resist lateral movement through the dead weight
of the wall. The design methodologies proposed by standards do not take into account the construction
sequences that simulate the process by which the soil and retaining wall are brought together. However, in
reality, at least during the backfilling process, the retaining wall undergoes many displacements that are not so
far considered in the design. In this investigation, effect of construction sequences in the gravity retaining
walls with different shapes is investigated with the help of finite element method. Two different construction
sequences, namely the backfilling after wall construction and the backfilling parallel to wall construction, are
compared for different wall shape models. Lateral displacement of the bottom and the top of the wall is plotted
for each model and construction sequence with construction stages. Bearing pressure distribution, lateral earth
pressure and failure wedge angle are summarized and compared with design values. Each wall showed
different behavior for each of the construction sequences. Back filling after wall construction minimizes the
sliding failure and bearing pressure. Overturning failure could be reduced by backfilling parallel to wall
construction. However, it was observed that, comparatively, backfilling after wall construction is more effective
than backfilling parallel to wall construction, suggesting that proper selection of construction method also
may reduce negative effects on the wall stability.
2015-10-01T00:00:00ZDetermination of tensile strain capacity of fresh concreteWeerasinghe, TGPLNanayakkara, SMAhttp://dl.lib.uom.lk/handle/123/179012022-06-21T08:41:07Z2015-10-01T00:00:00ZDetermination of tensile strain capacity of fresh concrete
Weerasinghe, TGPL; Nanayakkara, SMA
Hettiarachchi, MTP
Measuring physical properties of fresh concrete is important to understand the behavior of the
early phase of concrete. The measurement of tensile strain capacity of fresh concrete predicts the risk of
cracking due to restrained shrinkage. Fresh concrete means the concrete before the hardening phase which is
still in a semi liquid state. i.e. from right after mixing of concrete to 3 – 4 hours. Several research studies have
been conducted but complex test methods have been developed to measure both stress and strain and the average
strain was measured. The paper contains the procedure adopted to develop a simple test method to measure
the local strain along a sample. After verifying the test method, influence of cement type for early age tensile
strain capacity was studied. Ordinary Portland Cement, Fly ash blended and Portland Limestone Cement
were used. Concrete was mixed as a large quantity and kept inside the mixer and agitated every 10 minutes before
being taken out for testing. The method simulates the conditions where concrete is produced and kept inside
a truck mixer for a while before placing. Results indicate that fly ash blended concrete has a higher tensile
strain capacity than other cement types thus the mix is less vulnerable for early age cracking. Further tests
should be done to determine the influence of cement type for tensile strain capacity of undisturbed concrete.
2015-10-01T00:00:00ZIdentification of local soils for development of cricket pitchesPerera, WSUNawagamuwa, UPhttp://dl.lib.uom.lk/handle/123/179002022-06-21T08:42:46Z2015-10-01T00:00:00ZIdentification of local soils for development of cricket pitches
Perera, WSU; Nawagamuwa, UP
Hettiarachchi, MTP
Most of the Cricket batsmen in Indian subcontinent face a great difficulty in batting against fast
bowlers on English and Australian fast and bouncy wickets. The lack of having fast and bouncy pitches in
Indian subcontinent has led to this problem. It had been discovered that the pace and bounce of a cricket pitch
is governed by clay content, clay mineralogy and grass content of the cricket pitch. Local pitches were found
to have high silt content, low clay content and low plasticity due to a difference in clay mineralogy. In this research
“Grumusol” clay was discovered in Murunkan with a comparatively high clay content which is fulfilling
most of the required clay properties of a fast and bouncy wicket. Typical Sri Lankan clay sample used to
prepare wickets, Clay sample from Bangalore and the local “Grumusol” sample from Murunkan were tested
for the clay properties. Results showed that “Grumusol” is most suitable for constructing a fast and bouncy
wicket. Other than the clay as the basic material grass plays a vital role in binding the basic material together
and maintaining the required moisture levels in the wicket preventing the wicket from fracturing during the
game period. Here, Crouch grass was selected as the most suitable type of grass to achieve the desired output
of the fast and bouncy wicket.
2015-10-01T00:00:00Z