Geotechnical Engineering Journal of the SEAGS & AGSSEA

Influence of Initial Water Content and Water-to-Cement-Ratio on the Strength and Suction Characteristics of Cement-Stabilized Sediments from Drainage Canal

Dr. Supakij Nontananandh — Tue, 25 Jun 2024 00:00:00 +0700

This research aimed at investigating the basic properties of the canal sediments, which constitute waste materials dredged from drainage canal in Phetchaburi province. They were originally classified as silty sand with low shear strength due to their high water content and being unsuitable for construction use in their original conditions. An attempt was made to stabilize the canal dredged sediments with the Ordinary Portland Cement (OPC) in order to solve the environmental problems caused by the large amount of sedimentation to determine the potential use of construction materials based on the geo-environmental engineering framework. In this experimental study, air-dried canal dredged sediments were mixed with OPC by applying cement mix proportions of 150, 200, and 250 kg/m³and initial water contents of 14.32% and 17.0% with early curing times of 3, 7, 14, and 28 days in order to investigate the gain in strengths with different water-to-cement ratio (w/c ratio) using unconfined compression tests. The underlying mechanisms which contributed to the hardening effects were evaluated using moisture properties, suction test, X-ray diffraction analysis (XRD), and scanning electron microscopic observation (SEM). The results indicated that a desirable unconfined compressive strength of the cement-stabilized canal sediments of more than 689 kPa could be achieved after being cured for 7 days. Utilizing this criterion, the appropriate w/c ratio within the range of 1.00 - 1.50 ensured that the material had been suitable as a subbase layer for all mixing proportions. In addition, higher initial water content with similar w/c ratio played significant role in the strength development. These findings were confirmed by the formation of reaction products such as calcium silicate hydrate (CSH) and Ettringite which improved internal microstructures. In addition, Soil-Water Retention Curve (SWRC) revealed that an increase in suction significantly reduced water content which conformed to an increase in strength. The utilization of cement-stabilized canal sediments had the potential to be used as construction materials, representing a sustainable approach to waste management.

Optimizing Soil Characterization with Automated Pressuremeter Software Integration for the Pencel Pressuremeter in In-situ Testing

Farid Messaoud, Mohamed Salah Nouaouria, Paul. J Cosentino — Tue, 25 Jun 2024 00:00:00 +0700

The integration of the Pencel Pressuremeter (PPMT) model with the Automated Pressuremeter (APMT) software represents a significant advancement in in-situ soil testing. This combination simplifies the process of data reduction and analysis, resulting in substantial time savings. The APMT software efficiently records digital pressure and volume data, performs necessary calibrations, and offers quick access to essential strength and stiffness properties for engineering analysis. Through extensive testing conducted on various soil types, the integration of a linear potentiometer and a digital pressure transducer into the control unit has significantly improved the accuracy of digital volume measurements and pressure readings. Notably, the Stabilization Time (ST) for volume increments, as estimated by the APMT software, ranges from 20 to 70 seconds depending on the specific soil conditions. The APMT system not only enhances data quality but also minimizes the potential for human recording errors. It drastically reduces the time required for data collection and analysis when compared to manual methods, establishing itself as an efficient and precise tool for evaluating soil properties.

Mechanical Properties of Soft Clay Soil Improved with Nanomaterials and Chitosan Biopolymer

Tue, 25 Jun 2024 00:00:00 +0700

Soft clay soil is a concern in geotechnical engineering due to its low strength and high compressibility. Soil improvement with stabilization techniques is an interesting topic in the field of geotechnical engineering and pavements. Nanomaterials and biogeotechnical-based soil improvement are in high demand, as is the case with the objective of this research which is to determine the effect of the addition of nano lime, nano silica, and chitosan biopolymers to soft clay soil on its mechanical properties. The ratio of additives in this study was taken based on previous research, namely 2% nano lime, 4% nano silica, and 0.1% chitosan biopolymer from shrimp shell waste. Compaction and unconfined compression strength (UCS) tests were conducted on each specimen. The results show that mixing soil with nanomaterials and chitosan provides advantages in mechanical properties. This can be seen from the increase in the UCS value which is up to 11 times that of the initial soil and the increase in the maximum dry density value. Soil stabilization using nanomaterials and chitosan biopolymers has a good impact on the environment.

A Systematic Review on Slope Stability and Deformation Analysis Subjected to Rainfall and Earthquake

Partha Pratim Boruah, Jumrik Taipodia, Arunav Chakraborty, Aditya Kumar Anshu — Tue, 25 Jun 2024 00:00:00 +0700

The most common type of natural disaster is a landslide which impact millions of people and costing tens of thousands of lives and billions of dollars in damage every year. Earthquakes have the potential to trigger landslides of varying sizes in mountainous regions, endangering the residential communities situated at the base of mountains. The earthquake impact on the slope stability during the subsequent rains is not considerable in certain regions where the earthquake impact is not high enough to produce major soil movement. However, in some Landslide prone regions, the stability of slopes that are impacted by subsequent rains is significantly influenced by massive fissures on the surface of the slopes that are generated by earthquake shaking. The coupling effect of these two factors can significantly reduce the stability and safety of slopes, leading to catastrophic consequences. This paper reviewed the response of slopes under the combined influence of rain and seismic loading. This critical review highlights the importance of integrating rainfall and earthquake parameters simultaneously in slope deformation studies. In addition to slope stability analysis, slope deformation analysis should also receive equal attention. Future directions of this research should be focused on developing robust models and algorithms to simulate and assess slope failures caused by earthquakes and heavy rainfall in light of technological advancements, improvement of computational efficiency.

Updating the Background Seismicity Catalog in the Surabaya Area using USGS PSHA with a 2475-Year Return Period Study

Prastika Wahid Santoso — Tue, 25 Jun 2024 00:00:00 +0700

Seismic analysis is very important along with the development as well as the spatial and territorial layout of an area. However, unfortunately, the development of Indonesia's latest national earthquake hazard map still uses the 2017 earthquake database, not yet the latest seismic hazard catalog. This study presents an analysis using a new Probabilistic Seismic Hazard (PSHA) in the Java region, especially Surabaya, which is contains a very complex tectonic region. The Probablistic Seismic Hazard Analysis (PSHA) includes active faults, megathrust and intraplate subduction, as well as an updated background earthquake source database and attenuation equation. The logic tree method was used to quantify the epistemic uncertainty of the source parameter components. This research calculates the bedrock Peak Ground Acceleration (PGA) with a 2475-year return period for the greater Surabaya area, which has the greatest concentrations of population and business in East Java. The analysis shows the seismic hazard is dominated by the background source in the Surabaya area. The result of this study may be useful for updating the hazard map and attracting the interest of researchers to conduct research related to seismic hazards, especially in the Surabaya area.

Test Equipment and Application of Gas Preferential Flow Characteristic of Municipal Solid Waste

Gang Zeng — Tue, 25 Jun 2024 00:00:00 +0700

In order to study the gas preferential flow characteristics of municipal solid waste (MSW), a set of test equipment was independently developed. The experimental equipment had the function of measuring gas permeability, porosity and gas preferential flow parameters of MSW. The composition and operation method of the equipment were introduced. What's more, the laboratory tests on gas permeation of MSW under the influence factors of initial pressure and moisture content were carried out. The experimental results showed that the peak value of gas breakthrough curve increased gradually with the increase of initial pressure, and increased with the increase of moisture content. In addition, a mathematical model for describing gas preferential flow in the macro-porous region and the fractured region was established. The whole process of gas passing through the MSW was simulated by the established model. The model simulation results showed that the peak value of gas breakthrough curve increases with the ratio of fissure to pore permeability, while the time of gas passing through the sample decreases with the ratio of fissure to pore permeability. The peak value of gas breakthrough curve decreases gradually with the decrease of the proportion of fracture area in pore space.