Monitoring Report for Inclinometer & Piezometer

INCLINOMETER The use of the inclinometer for the investigation any potential failure and scour protection at piers. It can use for the following purpose: a) Measure lateral movement of the earthworks or structure b) Stability adjacent to excavation or underground work c) Deflection of piles, piers and abutment The inclinometer casing was drill to 20m depth from the ground level at the river bank of the Abutment B of the Batukawa Bridge. The monitoring was carried out 2 weeks once to check the lateral movement of the river bank due to the Road D construction. During the installation time and the base reading taken then road D was at the at the subgrade level. The following monitoring was taken during the construction of the sub- base of the road, compaction was carried out for the earthwork area. Beside the piezometers were installed at vicinity of the inclinometer to determine the pore pressure. The depth of the piezometers was located at 3m and 10m each from the ground level. The piezometer was installed to determine water level and the pore water pressure cause by the the road D construction and the fluctuation due to the water tie of Sungai Sarawak. The base reading for the inclinometer was taken on 31th Oct 12 and then 4th monitoring reading was carried out on 24th December 2012. After the field reading was taken, the incli-analysis will produce the graphical results. The analysis gives the absolute position, checksum and mean deviation. The observation of the slope stability at the river bank, any sign of (lateral movement) failure shall show from the data collected. Each time the data collected will plotted and show at the cumulative displacement for both direction Axis-A (toward river bank- A+) (toward Proposed Road D-A-)

GRAPH PROPERTIES Various graph properties can be manipulated as shown below In general, most inclinometer installations are designed to be finished in stable ground. Cumulative Displacement plots are thus created assuming the base of the borehole is at “zero” displacement. Data is summed from the base of the borehole to the top of the borehole (in the same manner as the inclinometer survey is performed). MEAN DEVIATION During an inclinometer survey, readings are taken at intervals of the probe length throughout the entire length of the borehole. The probe is then turned 180 degrees and the survey is repeated. Ideally, when each specific reading is summed, the result should be zero (see checksum). In reality, the sum is not zero as the probe always has a slight zero offset. In order to minimize the effects of this offset, an average is taken of the difference of the two readings [(A+) + (A-)]/2

The mean deviation plots this average data for each depth. The graph Axix- A show the red line and the blue line (base line) was different at the top of 1.5m which then casing which was above ground level should take as consideration of the lateral movement. The reading below 1.5 was found that not much different and less noise compared to the base line reading. Therefore the, checksum result was consider minor and closed to zero.

INCREMENTAL DISPLACEMENT The incremental displacement plot uses the mean deviation data and compares it to the baseline survey file. In turn, this plot reveals the exact depth where displacements are actually occurring. It has the advantage in that errors do not have a chance to accumulate (unlike the cumulative displacement plot).

The inclinometer was monitored on 24th December 2012 3pm the data collected and analysis using the incli-analysis program to generated the graphical plot. The displacement plots were generated in the unit (mm) the mean deviation compare to baseline reading at each depth was given (0.5m interval). The displacement was occurred at the depth of 1.5m to 4.5m from the Axis-a toward the river back with 0.5 E-3 m (0.9mm) compared to the previous monitoring reading of 0.5mm. For B the displacement happened the B- (left hand) at depth of 1.5m was obviously deviated if approximate of 0.45mm compared to data collected on 20-Nov-12 (0.2mm)

ABSOLUTE POSITION This plot reveals the actual shape of the inclinometer casing as it has been installed. Although it does not show displacements as well as the other plots, it can reveal whether potential errors are being caused by non-vertical casing.

The graphical results shown the casing was installed inclined of the maximum 280mm at Axix A+ to river after the grouting of casing was stable. It might due to the movement during the drilling and inserting the casing. The same phenomena happened to the Axix-B which inclined to the B- about 200mm away. No significant of movement from the casing shape plotted for depth below 1.5m to 21.5m depth.

CUMULATIVE DISPLACEMENT The most common presentation of inclinometer data, the cumulative displacement is the sum of the displacements from the base of the borehole. This plot shows the change in the position of the casing since the first set of readings. Caution must be exercised as this plot is very sensitive to errors in the probe. Changes in probe calibration (drift) over time can affect the data significantly if there has been significant movement of the casing from vertical. In general, rapid deviations from the centre line over a few sets of readings are more important than gradual changes.

By assuming the base of the casing was at the stable ground / hard layer. The reading shown that the soil from 1.5m depth to 21.5m depth was found the lateral movement of 2.2mm to A+ River (compared to pevious 1.2mm) to A- the proposed road construction after the compaction and sub-base and road base laying. For Axix-B the casing moved 0.75 mm to B-, monitoring shall continue to observe the ground movement for further study and investigate of slope stability.

CHECKSUM A checksum’s primary function is to verify data integrity (or quality) during a survey. A checksum is the mathematical addition of the A+, A- and the B+, B- readings from identical depths in the borehole. The checksum plot displays the checksum data for each depth interval. The most common cause of inaccuracies in inclinometer data is due to errors in probe placement. Large checksums are the often the result of these placement errors. Any jumps in the checksum data can indicate a questionable reading. Small drifts in checksum data over time can indicate aging and the bumps and shocks a probe takes over normal use. RST recommends calibration of the probe on an annual basis, or more frequently if the checksums confirm a problem with the probe.

The check sum was compare the reading taken below the ground from 1.5m to 21.5 m. maximum different at the 9m for Axix A around 0.3mm and for Axix B 12m depth to 21m was 0.4mm only.

PIEZOMETER The piezometer which installed at the 3m & 10m depth from to determine/ monitor the pore water pressure at the river bank of Sg. Sarawak. The data collected shall inter-relate with the inclinometer and the hydrograph water level for Batukawa.

The daily fluctuation of the daily for the 3m and 10m was compared. The monitoring period start on 28th September 2012 and the data collected were dated 23th November 2012. On going monitoring was carried out for month December 2012. The data collected found that the 23th November to 11th December 2012 and from period 11th December to 31th December 2012. The data obtained lost connection after 12/13/2012 4:30:00 PM. The data logger might distrusted. Therefore the data provided was insufficient for observed the pore water pressure for month December 2012. The maximum pore water pressures achieve 79.56 kPa at 12/10/2012 4:30:00 PM, and minimum pore water pressure is 59.51kPa at 12/2/2012 1:30:00 AM for the piezometer at 10m depth. The

maximum daily fluctuation was 18.35 kPa (or 1.83m different of water level) compared with the water level provided by hydrograph. The pore water pressure for the piezometer located at the 3m depth was showing the different trend of fluctuation compared with the piezometer at 10m depth. The significant increase after the contractor start the sub-base & road base construction at above location. The maximum pore water pressure of 4.64 kPa at 12/10/2012 4:30:00 PM, the effect of the water tie wad reducing compared before construction. The ground treatment have denser the ground condition and the saturation of water was lesser. The pore water pressure detected was increase from -0.2 kPa to + 1.5 kPa Average. The construction works seem affecting the pore pressure reading for the piezometer at 3 meter due to the extra loading applied to the ground level. But not affecting the piezometer under 10m depth.

Water level for Batukawa Bridge by Station ID 1502404 http://infobanjir.water.gov.my/wl_chart_scatter.cfm?state=SRK&station_id=439