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The Effects of Seismic Behavior on High Ground Stress Soft Rock Tunnel: A Review
No full textThe purpose of this review is to critically assess seismic activity's effects on soft rock tunnels under high ground stress scenarios. The paper seeks to identify key novelties and research gaps in the existing literature, offering new insights into analytical techniques, excavation methods, support systems, and monitoring technologies. A comprehensive review of recent studies was conducted, focusing on seismic behavior, analytical techniques, and mitigation strategies for soft rock tunnels. Case studies were selected based on their relevance to high ground stress conditions and their contribution to understanding seismic resilience. Significant findings include the identification of specific geological conditions that exacerbate seismic risks and the comparative effectiveness of various analytical techniques and support systems. Novel insights into the interaction of structural reinforcements and monitoring systems are also discussed. The review highlights new analytical techniques and advanced monitoring systems that improve predictive accuracy and early detection of seismic risks. It also proposes a refined approach to integrating mitigation strategies for enhanced tunnel resilience. Doi: 10.28991/CEJ-2024-010-09-020 Full Text: PD
Polyethylene Terephthalate Modified Asphalt Concrete with Blended Recycled Aggregates: Analysis and Assessment
No full textThe research study attempts to ascertain the mechanical performance of asphalt concrete, using reclaimed asphalt concrete pavement (RAP) and recycled concrete aggregate (RCA) blends with polyethylene terephthalate (PET) as a modifier. The influence factors were evaluated, including RAP/RCA ratios and PET contents on static and cyclic performances. The static performance was assessed through the indirect tensile strength (ITS) tests, while the cyclic performance was assessed through the indirect tensile resilient modulus (ITMR), indirect tensile fatigue life (ITFL), and wheel tracking tests. Compared to asphalt concrete using natural aggregate (NA), the ITMR of RAP-RCA-PET asphalt concretes was higher when PET contents were between 0.2% and 0.6% for RAP/RCA = 80/20. The ITFL of RAP-RCA-PET asphalt concretes was found to be higher than that of NA asphalt concrete when PET contents ranged from 0.2% to 0.6% for RAP/RCA < 90/10. The ITFL was also higher when PET content was between 0.4% and 0.6% for RAP/RCA = 100/0. RAP-RCA-PET asphalt concretes exhibited lower rut depth than NA asphalt concrete with RAP/RCA = 90/10 and 60/40 at PET contents of 0.4% to 1.0% and with RAP/RCA = 80/20 at PET contents of 0.2% to 1.0%. The RAP/RCA = 80/20 and PET content = 0.6% were found to be the best ingredient in term of both fatigue cracking and rutting resistances. As per the systematic analysis, the fatigue distress models of RAP-RCA-PET asphalt concretes for various PET contents were developed in term of ITFL and tensile strain (𔜀𔑡) relationship and useful for mechanistic design. The results of this research will contribute to promoting RAP-RCA-PET asphalt concrete as a greener material in pavement construction. Doi: 10.28991/CEJ-2024-010-11-08 Full Text: PD
Strength Characteristic of Lightweight Modular Block (LMB) Element using Stabilized Dredged Soil-EPS
No full textFor several decades, lightweight material applications have been extensively studied. Modifying various types of soil with EPS beads or lightweight geomaterials is an alternative construction material on site that can reduce excessive problems such as large deformation and lateral pressure. This study aims to examine the strength characteristics of lightweight geomaterials, namely lightweight modular block/LMB. LMB is composed of EPS beads, dredged soil, and cement. The cement amounts are 3%, 5%, 7%, and 9%, with EPS variations of 0.5% and 0.75% to the mixture weight. Laboratory tests were conducted to investigate the strength with unconfined compression and undrained direct shear tests. Before testing, the specimens were made using the one-layer static compaction method and were cured for 7, 14, and 28 days. This paper also presents explanations related to the specimens making and treatment by providing preliminary test results to compare the effectiveness of the three-layer and one-layer methods. Moreover, the curing treatments to avoid cracking were explained explicitly. The result shows linearity between both increasing the amount of cement and adding more curing time to the increase of the strength parameter. In contrast, adding more EPS decreased the strength, but adding cement helped increase the strength parameter with a remarkable value at C7% and C9%. Increasing the amount of EPS also reduced the density of the mixture by 18%–29%. Doi: 10.28991/CEJ-2023-09-03-014 Full Text: PD
Demand Modeling for Taxi and Ride-hailing Transport Services (RTS)
No full textThe rapid growth of Ride-hailing Transport Services (RTS) demand is found to have caused a fierce market share battle with conventional taxis in previous decades. In selecting a taxi or RTS, understanding the factors affecting passenger's decisions is substantial for better development and more reliable transit service. The aims of this study to evaluate the demand for taxis and RTS in the Jakarta Greater Area, Indonesia, using the demand-supply and dynamic models. It has been conducted by using 519 respondents, with the model inputs consisting of waiting and travel time, trip costs, and the destination of the conventional passengers. Moreover, the choice between taxi and RTS was analyzed based on the stated preferences of respondents. The results showed that the waiting and travel time, as well as costs per trip of RTS, were 1.49 and 2.67 minutes lower and IDR10,902 cheaper than a taxi, respectively. The factors influencing the demand for these transport modes were also the number of trips per-day, mode share, the average vehicle occupancy, operating hours/day, passengers and driver waiting time, as well as travel period. In the dynamic model, the addition of variable service area, peak hour, and average vehicles speed was subsequently observed. Based on the results, the requests for these transport modes in the Greater Area of Jakarta were 64,494 and 55,811 vehicle units for the demand-supply and dynamic models, respectively. This proved that the dynamic model was better than the demand-supply, due to the added parameters representing the area's traffic characteristics. Additionally, subsequent future research are expected to focus on modeling of taxi and RTS demands through the global positioning system data, as well as analysis using machine learning and deep learning. Doi: 10.28991/CEJ-2023-09-05-03 Full Text: PD
Analysis of Combined Vertical and Radial Consolidation of Soil under Time-Dependent Loading
No full textFine-grained compressible soils are usually associated with strength challenges in the course of carrying structures, roadways, embankments, and other civil engineering facilities. In addition, due to their low permeabilities, compressible soils take an awfully long duration to achieve optimal consolidation, with its attendant negative effects on the facilities supported by the soils. Engineering practitioners and researchers have established the efficacy of vertical drains for accelerating the consolidation process of such soils through the shortening of horizontal flow distances, thereby stabilizing them and improving their load-bearing capacities. Application of the pre-loading surcharge provides additional drive for rapid consolidation. The case of soils carrying time-dependent loading is quite topical because it reflects reality most appropriately. However, a rigorous analysis of soils undergoing vertical and radial consolidation with a constant or time-varying surcharge is conspicuously lacking in the literature because most authors of publications in this subject area have largely based their solution procedure on the assumed decoupling of the vertical and radial flows by treating their associated pore pressures as separate. This assumption, notwithstanding the simplification it introduces into the mathematics of the problem, is not supported by physics. Therefore, the theory presented herein aims at addressing that gap in the literature. Throughout this analysis, the coupled (vertical and radial) flow, driven by a common pore water pressure, is handled as a single process. Successive applications of the integral transformations of Laplace and finite Hankel have been used to obtain an explicit expression for the image of the pore water pressure as a function of the transformation parameters. This is followed by successive inversions of the integral transforms, leading to a closed-form solution in the sense of a generalized Fourier series. The classical definition of the average degree of consolidation is easily applied in this case, unlike other methods in the literature that rely on the principle of superposition, whose applicability in this circumstance remains questionable. The validity of the present analysis has been established through logical checks and comparison with previous results in the literature. This theory has been proven to be applicable to cases of constant as well as time-varying surcharges. Doi: 10.28991/CEJ-2023-09-01-014 Full Text: PD
Reliability Assessment of Masonry Infilled RC Frame Building's Earthquake Performance through Accidental Torsion Consideration
No full textAccidental torsional behaviour induced by horizontal loading is difficult to predict, being a complex phenomenon governed by many variables. This problem gains an additional dimension of complexity when nonlinear responses with imperfections need to be considered. Therefore, evaluation and understanding the influence of accidental torsion are fundamental in seismic reliability estimation. This study offers vital insights based on the results of a 1/2.5 scale three-story masonry infilled reinforced concrete frame building's test on a shaking table. The building was tested under ten consecutive ground motions with increasing ag/g, recorded at Herzeg Novi station during the 1979-M6.9 Montenegro earthquake. The accidental eccentricity, considered a random variable, resulted from unsymmetrical masonry infill wall damage in an otherwise regular building. Its effect, in relation to that of other random (design) variables, was evaluated utilising weight factors and, in addition, assessed through various building code provisions and state-of-the-art research findings. The analysis revealed that the accidental eccentricity, as compared to other random variables considered, could, under certain conditions, reach values higher than those prescribed by the building codes. This unacceptable seismic reliability clearly warns that accidental torsion of masonry-infilled reinforced concrete frames in in-situ conditions must be considered even in regular buildings. Doi: 10.28991/CEJ-2023-09-02-017 Full Text: PD
Behaviour of Steel I Beams with Web Openings
No full textThis paper aims to study the behavior of steel I beams with web openings. However, web openings might lead to a noteworthy reduction in the load-carrying capacity of beams, but can also be so supportive and essential from an economic point of view. An experimental investigation and nonlinear three-dimensional finite element analysis using the ABAQUS computer program were planned and conducted on six steel I-beams having the same dimensions, different diameter ratio spacing, and opening shapes such as circular, rectangular, and hexagonal. Experimental results showed that the ultimate load of a steel beam with web openings reduced with an increase in the area of the opening. A circular opening has a stronger shape than a rectangular opening because a rectangle has fast deflection and torsion angles, so it resists an applied load less than a circular opening. Also, the beam with hexagonal openings is better than that with rectangular openings because hexagonal openings are more resistant to deflection and deformation than rectangular openings. The finite element results, which are validated against the experimental results, show good accuracy with the experiment. Besides, a parametric study is presented here to study the influence of varying the shape of openings on the value of the failure load and midspan deflection. It can be noticed that the steel beam with a circular opening, which had been tested experimentally and modeled by the Abaqus program, is the best case and gives a higher failure load as compared to the diamond, octagonal, trapezoidal, transverse, and longitudinal ellipses. Thus, providing web openings reduces the weight and increases structural efficiency. Doi: 10.28991/CEJ-2023-09-03-08 Full Text: PD
Stress Path Behaviour and Friction Angle Transition Due to the Cyclic Loading Effects
No full textIn various aspects, peat soil is different from mineral soil. Peat is a biogenic deposit that emerged within the last 10,000 years, during the post-glacial (Holocene) era. Peat is a soft soil that is unable to support external loads without experiencing significant deformations. Tyre pressure from automobiles and/or aeroplane wheels on paved surfaces creates traffic load, which can manifest as static or dynamic types of loading. To resolve the problem with peat soils, a thorough understanding of the static and dynamic behaviour of peat is still required. Many people who live near regularly used highways feel traffic vibration, and it is important to comprehend the nature of this issue to make predictions about potential solutions to this problem. As such, this study aims to investigate the cohesion (c) and friction angle (φ) properties of peat soil after it has been subjected to cyclic stress. Monotonic triaxial tests are conducted to ascertain the initial shear strength characteristics of the soil. Cyclic triaxial tests are performed with half of their maximum deviator stress to simulate the behaviour of peat soil under various effective stresses and frequencies of loading that are applied with 100 number of cycles. After applying various numbers of cycles of dynamic loading, the post-cyclic monotonic shear strengths were subsequently evaluated. It has been noted that irregular behaviour tends to occur more frequently at higher frequencies, particularly between 2 and 3 Hz. With higher frequencies being applied, the reduction in cohesion and friction angle becomes more evident. Doi: 10.28991/CEJ-2023-09-04-010 Full Text: PD
Labor Productivity Study in Construction Projects Viewed from Influence Factors
No full textProductivity is one of the fundamental factors affecting competitiveness in the construction industry. Construction and productivity are two things that are interrelated. This study aims to identify the factors and model relationship these factors that affect labor productivity using the Structural Equation Modelling (SEM) in road construction projects in Indonesia as seen from each side area I, II, and III, respectively. The results obtained the factors that influence labor productivity in road construction projects in Indonesia, namely field conditions, time, financial factors, and internal labor. The study's findings indicate that internal labor is one of the elements influencing labor productivity in Indonesian construction projects, particularly road maintenance work. Labor productivity research in Indonesia is conducted by comparing planned and realized labor productivity calculations, which are conducted by collecting project data and making firsthand observations of work in the field. Labor productivity is measured using characteristics other than the variables used in the research, as well as a larger population and sample coverage. The findings of this study can be utilized as input for government agencies in determining the ability of specialists to carry out work in the field connected to the preservation of non-structural flood handling roads on Indonesian territory. Doi: 10.28991/CEJ-2023-09-03-07 Full Text: PD
Applying the Porosity-to-Cement Index for Estimating the Mechanical Strength, Durability, and Microstructure of Artificially Cemented Soil
No full textFine, expansive, and problematic soils cannot be used in fills or paving layers. Through additions to these soils, they can be converted into technically usable materials in civil construction. One methodology to make them viable for construction is through a stabilization process. Nevertheless, current methodologies regarding dosage based on compaction effort and the volumetric amount of binder used are unclear. Thus, this research describes cement-stabilized sedimentary silt's strength and durability properties from Curitiba (Brazil) for future application in paving. Splitting tensile strength, unconfined compressive strength, and loss of mass against wetting and drying cycles (W-D) were investigated in the laboratory utilizing greenish-gray silt (originating from one of the Guabirotuba Formation layers, Paraná) and high-early strength Portland cement- ARI (CPV). Utilized were cement concentrations (C) of 3, 5, 7, and 9%, molding dry unit weights (d) of 14, 15, and 16 kN/m3, curing periods (t) of 7, 14, and 28 days, and constant moisture content (w) of 23%. With an increase in cement concentration and curing time, the compacted mixes demonstrate an increase in strength, an improvement in microstructure, and a decrease in accumulated mass loss (ALM) and initial porosity (η). Using the porosity/volumetric cement content ratio (η/Civ), the lowest amount of cement required to stabilize the soil in terms of strength and durability was determined. The porosity/cement index provided an appropriate parameter for modeling the mechanical and durability properties, and a unique equation between the strength/accumulated loss of mass and the porosity/binder index was obtained for the curing times studied. Lastly, C = 5% by weight is the minimum acceptable amount for prospective subbase soil application. Doi: 10.28991/CEJ-2023-09-05-02 Full Text: PD