Siti Noor Linda Taib

Effect of alkali on tropical peat stabilized with different stabilizers

Abstract The paper presents the effect of alkali on tropical peat stabilized with ordinary portland cement (OPC), fly ash (FA) and different chemicals e.g., accelerator (a combination of 2.0% sodium sulfate, 0.5% sodium chloride and 0.1% triethanolamine); 2.6% aluminum sulfate; and 2.6% calcium sulfate. Various physical and engineering properties tests were conducted on original peat, FA and stabilized peat samples to check the effect of alkali and chemicals. Unconfined Compressive Strength (UCS) tests were carried out on treated (i.e., peat treated with 2% NaOH to reduce its acidity) and untreated stabilized peat samples with OPC, FA, and different chemicals for various curing periods. The results show that UCS value increases with curing periods and treated peat samples show better results than untreated peat for both OPC and FA stabilized peat samples. The highest UCS value was found on treated stabilized peat where calcium sulfate and OPC were used as stabilizers for 120 days curing period. In addition, specific gravity (Gs), pH, loss on ignition (N), Organic Content (OC) and Scanning Electron Microscope (SEM) studies were also carried out on stabilized peat samples to investigate the stabilized behavior and micro-structure of the peat.

Correlation between different physical and engineering properties of tropical peat soils from Sarawak.

The present paper describes the physical and engineering properties of tropical peat soils from Sarawak, Malaysia. Different physical properties such as organic content (OC), liquid limit (LL), fibre content (FC), specific gravity (Gs) and engineering properties (mainly the standard Proctor test) have been conducted on remoulded peat soil samples. The results show that, the value of LL, FC, Optimum Moisture Content (OMC) increases with an increase in OC. Also the results show that, Gs and MDD decrease with increasing values of OC. Furthermore, the plot of OC against Gs from the current study is compared with other researchers; whereby the correlation shows that R2 values ranges from 0.71 to 0.95. This demonstrates that findings on local peat soils from Sarawak are in good agreement with other researchers as similar trends are observed. Consequently, geotechnical engineers can refer these correlations to comprehend the preliminary behavior of peat soil, where the geotechnical data are not readily available.

Landslide Susceptibility in Relation to Correlation of Groundwater Development and Ground Condition

Rainfall is inevitably one of the main factors that trigger landslides. However, not much study has been conducted on the impact of groundwater rise on slope stability. Thus, this study is intended to focus on the rise of the groundwater level from the bottom of the slope which would lead to landslides due to pore pressure development by eliminating other landslide-triggering factors (i.e., infiltration and surface runoff). Saturated sand was used for slope modeling, and sand densities of 1523u2009kg/m3, 1562u2009kg/m3, and 1592u2009kg/m3 were tested with a constant slope angle of 45°. Another set of experiments was also performed on slopes having angles of 25°, 45°, and 60° and with a maintained density of sand at 1562u2009kg/m3. Through observation, failure was initiated first at the toe of the slope before minor and major slips or total collapse occurs. Dimensions of slip surfaces were measured and included in SLOPE/W for the computation of the safety factor. In conclusion, safety factors are found to be higher in denser soil and in the lowest slope angle. However, faster occurrence of collapse in denser soil was identified and could be contributed by the faster pore water pressure development.

Variable penetration rate testing for shear strength of peat – a review

Abstract This paper presents a review of the advances in the variable penetration rate testing methods on inorganic soils and its potentials to investigate the appropriate penetration rate and resistance factors for penetrometer testing of peat. A partially drained condition, which often leads to misinterpretation of test results, has been observed in peat penetration testing when the standard rate of 20 mm/s is used. Although the impact of rate-effects on penetration resistance measured with CPTu, T-bar and ball penetrometer have been investigated extensively in various intermediate soils, research is limited on how penetration rate controls drainage conditions and affects consolidation behaviour in peat. This review synthesises research developments in using variable penetration rate tests. The objective is to evaluate the transition of drainage conditions and consolidation behaviour of inorganic soils while focusing on its adaptability for peat. The review provides guidance on the investigation of the penetration rate testing in peat.

Temperature change and the total stress anomaly in paste backfill

This paper presents preliminary results from a laboratory backfill model test in order to explain the effect of temperature change during the cement hydration on the total stress within cemented paste backfill. It is conducted via temperature control test in the absence of the cement. This investigation is an attempt to resolve an anomalous behavior reported in recent full scale monitoring reports, where the total vertical stress at the stope base shows a progressive increase after backfilling is terminated. The result in this paper shows that the total vertical stress is not affected by the level of the temperature but rather by the temperature gradient. The empirical relationship between the temperature gradient and the change in the total vertical stress is proposed. The total stress anomaly found in the full scale monitoring of paste backfill could be explained by the finding.

Measurement of Amorphous Peat Shear Strength in the Direct Shear Box at High Displacement Rates

The ASTM standard provides guidelines for the drained direct shear test (DST) and requires the samples to be sheared at rates estimated from time to failure,

Evaluation of Critical Parameters to Improve Slope Drainage System

t_{f} ge 50t_{50}

Application of Horizontal Slice Method (HSM) on Soil Nailed Slopes

tf≥50t50 (where