GEOMATE Journal

EVALUATION OF THE EFFECT OF TURBID WATER IN CANALS ON UNDERWATER ULTRASONIC ROUGHNESS MEASUREMENTS

Nozomu Urahata, Kenji Okajima — Sun, 30 Jun 2024 00:00:00 +0000

Abrasion occurs on the concrete surfaces of irrigation canals because of the flow of water and sand. Abrasion increases the roughness of the concrete surface. Increased roughness reduces water flow function. Underwater ultrasonic roughness measurements estimate roughness from the peak-to-peak strength of reflected underwater ultrasonic waves. However, the effect of turbid water flowing in a canal on peak-to-peak strength has been unclear. The objective of this study was to evaluate the effect of turbid water on underwater ultrasonic roughness measurements. The characteristics of the attenuation of the peak-to-peak strength of underwater ultrasonic waves were investigated as a function of the particle size and concentration of suspended solids. The suspended solids used in the experiments were kaolin with a particle size of 0.5 µm and alumina with particle sizes of 2, 4, and 8 µm. Peak-to-peak strength was measured as a function of the concentration of each particle size. The experimental results indicated that peak-to-peak strength was attenuated only with increasing concentrations of suspended solids and was not affected by particle size. A proposed correction equation for peak-to-peak strength took into consideration the concentration of suspended solids in turbid water. The coefficient of determination between this equation and measured data was as high as 0.98. Using this correction equation, peak-to-peak strength without turbidity could be calculated from peak-to-peak strength measured in turbid water. It is thus possible to make effective use of underwater ultrasonic roughness measurements in turbid water.

INFLUENCE OF IMPERFECTION IN LENGTH AND LOADING ON DYNAMIC RESPONSE OF TRUSSES UNDER HARMONIC LOAD

Thuy Van Tran Thi, Ngoc Tien Dao, Bich Quyen Vu Thi — Sun, 30 Jun 2024 00:00:00 +0000

In structural engineering, trusses are important for covering large-span structures. However, imperfections are often present in the manufacture and assembly of truss structures, particularly in terms of the length and loading. This article presents the influence of imperfection, both in length and loading, on the dynamic response of trusses under harmonic loads considering geometrical nonlinearity. To analyze trusses, the hybrid matrix of elements of the truss is established to solve dynamic equations by applying the Newmark integration and Newton–Raphson iteration methods. The authors continue to develop the previous study by investigation of the influence of two imperfect parameters of structures in terms of element length and loading. An incremental-iterative algorithm was developed, and a calculation programming routine in MATLAB software was written to illustrate the dynamic responses of trusses with imperfections under harmonic loading. The results obtained in this study verified the accuracy and effectiveness of the proposed approach in the analysis of trusses under harmonic loading. The numerical results show that when considering both length and load imperfection, the dynamic response of the trusses is significantly different in comparison to the case of consideration of length imperfection separately. With consideration of both imperfect parameters in length and loading, the critical load is significantly decreased. From there, it can be concluded that, in the dynamic analysis of trusses, all possible imperfect parameters, especially in element length and loading, must be considered.

SIMULATION OF EARTHQUAKE INTENSITY FOR TSUNAMI PREDICTION AND DISASTER RISK MANAGEMENT

Yusran Asnawi, Muhammad Gunaya, Suko Prayitno, Andrean Simanjuntak, Umar Muksin — Sun, 30 Jun 2024 00:00:00 +0000

On January 15, 2023, a major earthquake with Mw 6.2 occurred in the northern part of Sumatra, Indonesia, and generated widespread ground shaking around III – V MMI without any damages. The hypocenter was located at a shallower depth than the common slab contour, which may address another blind tectonic system called backthrust. An extended waveform inversion and hypocenter relocation analysis is demonstrated to identify the responsible system. A total of 1,750 earthquakes were compiled from the 10-year catalog (2010 – 2022) and recorded by 72 stations associated with 1,2536 P-phase and 5,604 S-phase. Up to 85% (1211) of the total earthquakes were successfully relocated, while 15% (103) were not relocated because they did not meet the predetermined criteria. Furthermore, the mainshock was resolved with a thrusting fault with NW – SE orientation, steeply dipping to the SW direction, and a moment magnitude estimation of Mw 6.2 ± 0.03 at a depth of 35.50 ± 2 Km. The focal parameters include two nodal planes, i.e., the 1^st nodal plane with strike 319°, dip 15.5°, and rake 101° while the 2^nd nodal plane with strike 127°, dip 74.8° and rake 86.8°. The results successfully show the existence of the blind back thrust in the Sumatra subduction zone, which will provide new insight and contribute to the recent tectonic system in the northern part of Sumatra and its surroundings.

PRELIMINARY LABORATORY STUDY ON EXPANDABLE GROUND ANCHORS FOR EXPANSIVE SOIL

Sun, 30 Jun 2024 00:00:00 +0000

Expansive soil is one of the problematic soil types due to its potential to swell highly when moisture content increases and shrink when moisture decreases. The soil exhibits mechanical behavior that is highly sensitive to changes in natural moisture content influenced by environmental factors such as infiltration and evaporation. It has the potential to damage civil structures such as road pavement and lightweight buildings. An alternative method to overcome this phenomenon is the use of ground anchors, a structural element installed into a soil or rock layer to withstand the tension load. An expandable ground anchor is proposed as an alternative to overcome the drawback of a helical anchor. Wings are installed in such a way that additional passive pressure is developed. The study was firstly conducted by performing anchor pullout capacity tests on a dense sand layer, followed by a swelling test of expansive soil, and finally, the performance test of ground anchor to withstand swelling pressure using three different sizes of steel box anchor prototypes, 4 cm × 4 cm × 30.5 cm, 5.5 cm × 5.5 cm × 30.5 cm and 7 cm × 7 cm × 30.5 cm. A series of anchor pullout capacity tests were conducted on a 90 cm dense sand layer, continued by a swelling test of 25 cm expansive. The result indicates that an expandable anchor can significantly withstand the swelling of expansive soil.

WEATHERED MARBLE AS AN ALTERNATIVE EMBANKMENT MATERIAL FOR ROADWAY DEVELOPMENT IN NORZAGARAY, BULACAN

Sun, 30 Jun 2024 00:00:00 +0000

Road networks facilitate socioeconomic growth in developing countries, such as the Philippines. An increased traffic volume exacerbates the gradual progression of erosion, breaching, and degradation of road embankments. Weathered marble from local quarries in Norzagaray, Bulacan, was repurposed to provide an economic solution. This study quantified the effect of five varying proportions of weathered marble and aggregate on index properties, such as specific gravity, grain size distribution, plasticity, and compaction, and assessed the capacity of the embankment against vehicular loads using the California bearing ratio and direct shear tests. A mix of 60% marble and 40% aggregate (60M40A) was determined to display the best performance in terms of maximum dry density (20.512 kN/m³) and California bearing ratio (78%). The Proctor compaction test results indicated a very stable embankment according to the USCS criteria and good to excellent embankment performance according to the AASHTO criteria. The local criteria on embankment marked the 60M40A samples as an excellent material for the embankment base layer. The same specimen demonstrated the highest shear strength before failure and had the highest friction angle before failure (37 degrees). These results indicate that weathered marble exhibits excellent compaction behavior, yields friction angles comparable to well-graded soil, and possesses a suitable load-bearing capacity, thus establishing its feasibility as a potential material for road embankments, especially in rural areas within proximity to marble quarrying sites.

EXPERIMENTAL STUDY ON THE BOND STRENGTH BETWEEN REPAIR MORTAR AND CONCRETE SUBSTRATE

Leandro Madeira Branco, Abel Fernandes , Isamu Yoshitake — Sun, 30 Jun 2024 00:00:00 +0000

Concrete is widely used in infrastructure projects worldwide, including Timor-Leste, a newly independent country struggling to advance its social and economic development. Concrete repair and rehabilitation are critical for extending its service life. The effectiveness of the repair depends on the strength of the bond between the repair material and the concrete substrate. This experimental study focused on the bond properties of ordinary performance cement mortar (OPCM) and polymer-modified cement (PMC) mortar and also examined the interfacial bond strength under tension, shear, and a combination of both. Slant shear and double shear tests were conducted to investigate the bond strength. The test results showed that the epoxy resin used as an interfacial bonder exhibited a lower bond strength than the other test parameters. The results obtained from the tests indicated that the expected interfacial bond strength was achieved between the repair material and concrete substrate using the proposed method. The use of OPCM in repairs is considered sustainable and applicable in countries where access to repair materials is difficult, as experiments have shown satisfactory results with existing repair materials and combinations.

NUMERICAL SIMULATION OF WAVE REDUCTION WITH MANGROVE FOREST USING DELFT3D MODELING AT BANYUGLUGUR BEACH

Retno Utami Agung Wiyono, Gusfan Halik, Slamet Waluyo, Risqi Sofiana — Sun, 30 Jun 2024 00:00:00 +0000

Coastal erosion caused by continuous sea wave action is destructive. One potential solution to reduce the impact of waves and coastal erosion is the utilization of mangrove forests as natural barriers. The Banyuglugur Coastal Area has a thriving mangrove forest that grows along 5.1 km of coastline. The objective of this research is to determine the percentage reduction of the mangrove forest as an energy buffer and the wave height along the Banyuglugur Coast. The method employed to achieve this goal involves numerical simulation using Delft3D, considering the influence of mangrove forest length, tides, wind, and wavelength. The Delft3D-Coupling model is used, combining two modules, FLOW for tidal simulation and WAVE for wind-wave simulation. Mangroves with a width of 70 m in Zone A are high-density mangrove locations that can reduce wave energy by 62.14%, while low-density mangroves in Zone D with a width of 30 m can reduce wave energy by 44.28%. The simulation results indicate that mangrove forests on Banyuglugur Beach, with an average width of 50 m, can dampen waves by an average of 52.8% and reduce the average wave height by 39% compared to incoming waves.

COMPARATIVE ANALYSIS OF OVERLAY THICKNESS USING THE ASPHALT INSTITUTE’S AND MEPDG WITH KENLAYER

Sun, 30 Jun 2024 00:00:00 +0000

The Mechanistic-Empirical Pavement Design Guide (MEPDG) is widely regarded as the current state of the art in mechanistic-empirical pavement analysis and design. The guide offers a comprehensive set of procedures for determining overlay thickness, a crucial aspect of pavement design. The objective of this study is to investigate the differences that arise when designing overlay thickness using two distinct methods: the Asphalt Institute's mechanistic-empirical and the MEPDG. This study utilized KENLAYER software, which enables stress and strain analysis by modeling the nonlinear elastic pavement structure. Accordingly, the Asphalt Institute method solely relies on alligator cracking and rut depth as its failure indicators, while the MEPDG encompasses several additional criteria that serve as determinants for evaluating the performance of pavement structure. The subject of this study is flexible pavement situated on a road located in West Java, Indonesia. Following this, a falling weight deflectometer (FWD) test was conducted to obtain the deflection characteristics of the road. This paper provides a detailed explanation of overlay thickness calculation processes employed in both the Asphalt Institute's mechanistic-empirical and the MEPDG method. The Asphalt Institute Method resulted in a slightly thicker overlay of 30 cm, while the MEPDG method produced a thickness of 25 cm. To adapt and apply MEPDG effectively in Indonesia, adaptations such as employing Weigh-In-Motion data for load spectra and conducting local calibration are necessary.

EFFECTS OF LIQUEFACTION COUNTERMEASURE USING BURIED GABION INSTALLED TO SHALLOW FOUNDATIONS

Hiroyuki Araki — Sun, 30 Jun 2024 00:00:00 +0000

Liquefaction damage to small buildings, such as detached houses, has been conspicuous in recent earthquake disasters. To mitigate liquefaction damage in residential areas with existing houses, it is reasonable to take measures to mitigate damage to buildings even if liquefaction occurs rather than improving the ground to prevent liquefaction. However, few damage-mitigation measures have been applied to existing buildings. This study proposes a method for mitigating settlement by burying gravel-filled geogrid gabions on the sides of existing or newly constructed foundations. In addition, it evaluates the effect of using gabions to mitigate settlement by shaking table tests using a physical model. The results showed that installing geogrid gabions reduced the settlement of existing strip foundations by 40%-60% compared with that without geogrid gabions. The settlement of the existing mat foundation was reduced by half compared to that without geogrid gabions, depending on the conditions. The gabions were assumed to reduce foundation settlement by locally suppressing liquefaction around the ground.

A STUDY OF RADIO WAVE PROPAGATION IN THE CAVE FOR DEVELOPING THE THROUGH-THE-EARTH APPLICATION

Sun, 30 Jun 2024 00:00:00 +0000

Radio waves are significant for operating in an underground tunnel or a cave, such as two-way radio systems or emergency communication during rescue operations. Most applications used in the tunnels require wired connections because of the high attenuation of the wireless propagation. In particular, the attenuation in caves is higher than in tunnels because of the non-uniform nature of the walls. Therefore, this paper presents a study of the radio wave propagation within a cave. The experiment covers the low-frequency (LF) to ultra-high frequency (UHF) bands that aim to analyze the attenuation and behavior of waves in caves. Study results show that the low frequency and medium frequency (MF) bands can penetrate cave walls due to the deeper skin depth. At the same time, higher frequencies perform well in line-of-sight (LOS) propagation over short distances, albeit encountering significant attenuation in non-uniform cave environments. The skin depth condition obtained in the propagation result led to the Through-the-Earth (TTE) experiment by making two hand-made transceivers in the beginning band of MF at 350 kHz for transmitting and receiving waves between the mountain surface and the cave passage directly through the rock layer. The results of the TTE experiment show that the transceivers can transmit to 571 meters with a received power of -85.0 dBm before encountering an obstacle that makes it impossible to continue. Finally, the results are significant for developing the application of radio frequency within caves or tunnels and improving the application of the TTE technique with more versatility and efficiency.

THE EFFECT OF DIFFERENT CONCRETE MIX DESIGNS AND MAXIMUM AGGREGATE SIZE VARIATIONS ON THE COMPRESSIVE STRENGTH OF NORMAL CONCRETE

Yusep Ramdani, Nur Azizah, Nina Herlina — Sun, 30 Jun 2024 00:00:00 +0000

Each component of the material that makes up concrete has a significant influence on its mechanical properties, so a mix design is needed to obtain the optimum concrete quality. This research uses three mix design methods, namely based on SNI 03-2834-2000, SNI 7656:2012, and Dreux Gorisse. SNI 03-2834-2000 refers to the DOE method from the UK, while SNI 7656:2012 adopts the ACI method from America. SNI 03-2834-2000 and SNI 7656:2012 are the applicable methods in Indonesia. While Dreux Gorisse is a concrete mix design method originating from France. This study aims to analyze the effect of concrete mix design and maximum aggregate size variation on the compressive strength of normal concrete. The maximum size of coarse aggregate used was 10, 20, and 40 mm. The planned concrete quality (f'c) was 25 MPa with cylindrical specimens measuring 15x30 cm. The highest compressive strength test results at the age of 28 days are with the SNI 7656:2012 method for a maximum aggregate size of 10 mm at 31.33 MPa. While the lowest compressive strength value with Dreux Gorisse for a maximum aggregate size of 40 mm was 25.38 MPa. In all mix design methods, the smaller the maximum size of coarse aggregate, the higher the compressive strength value. The maximum aggregate size of 10 mm in the SNI 7656:2012 method resulted in an increase in the maximum compressive strength by 25.31% from the planned compressive strength because it has a lower w/c ratio and slump values of 0.49 and 65 mm.

WORKABILITY, MECHANICAL AND DURABILITY INVESTIGATIONS ON SELF-COMPACTING CONCRETE WITH HIGH FLY ASH CONTENT AND RECYCLED FINE AGGREGATE

Nguyen Hung Cuong — Sun, 30 Jun 2024 00:00:00 +0000

Currently, in Vietnam, the natural sand resource is depleted; thus, it is unable to meet the growing demand for construction. In this context, recycled fine aggregate (RFA) from waste concrete emerges as an effective alternative for sand in the production of self-compacting concrete (SCC). In this paper, the author presents the experimental results on the properties of SCC with high fly ash content using RFA. The research utilizes RFA to replace natural sand at the rates of 0% and 100%, respectively while applying fly ash concurrently at a 50% volume ratio of cement. The evaluated properties of the SCC include its workability, compressive strength, flexural tensile strength, chloride ion permeability, and water absorption. The research results show that the use of RFA combined with high fly ash content can produce SCC that meets EFNARC requirements, with only a 1.48% reduction in compressive strength, 1.85% decrease in flexural tensile strength, 19.79% reduction in chloride ion permeability, and 5.12% increase in water absorption compared to the use of natural sand. These findings demonstrate the effectiveness of incorporating RFA and high fly ash to replace natural sand and cement in SCC production, opening up prospects in the construction industry with positive environmental impacts.

POROTHERMOELASTIC MODEL FOR ANALYSIS OF STRESS STATE AROUND WELLBORES IN ANISOTROPIC ROCK

Tran Nam Hung, Pham Duc Tiep, Nguyen Van Hieu — Sun, 30 Jun 2024 00:00:00 +0000

Analyzing the stress state around wellbores, and thereby the safe mud pressure window, is an indispensable task in the design as well as assessment of wellbore stability. As considering a realistic behavior model of materials, distributions in the literature mainly referred to the development of analytical or numerical calculation models without mentioning the stress state around the wellbore related to the form of well wall instability. This study aims to analyze the stress state of the rock mass around the wellbore in a homogenous porothermoelastic anisotropic rock based on the finite element method. Two scenarios involving thermal conditions at the well wall are taken into account, i.e. cases of “cooling” and “heating” the wellbore. The coupled thermo-hydro-mechanical behavior model of the rock is used to describe instantaneously the thermic, hydraulic, and mechanical processes and their reciprocal interactions. The results showed that the temperature conditions on the well wall strongly affect the stress distribution around the wellbore, and thereby the stability of the well wall. For the cooling case, the compressive stress around the well wall is not large, but high tensile stress can appear, especially for the axial stress component which can reach 23 MPa. For the heating case, both the compressive tangential and axial stresses with very high values occur around the wellbore ranging from 70-75 MPa. The parametric study showed that the degree of anisotropy of Young’s modulus, thermal expansion coefficient, as well as bedding angle of the transversely isotropic rock, strongly affect the stress distribution around the wellbore

A COMPUTER-BASED PROGRAM FOR PILE DESIGN WITH CONSIDERATION OF RESISTANCE, SETTLEMENT, AND NEGATIVE FRICTION SIMULTANEOUSLY

Hoa Cao Van — Sun, 30 Jun 2024 00:00:00 +0000

Pile design is an important aspect of construction engineering, and it involves the use of physico-mechanical formulas that are suggested by national standards. Finite element software can be used to validate the results obtained from these formulas. According to design standards, pile group design usually determines the resistance capacity with a large safety factor. This safety factor is meant to maintain the elastic behavior of piles in the soil environment. However, pile group settlement is often calculated based on different theories, such as equivalent rafts, which can make it challenging for engineers to understand piles' resistance and settlement behavior. To overcome this limitation, a study was conducted using a modified Unified Method integrated with MATLAB programming. This resulted in a program that can compute the bearing capacity and validate the elastic behavior of pile-soil interaction while using reasonable safety factors. The program simultaneously calculates piles' bearing capacity and elastic settlement based on unified soil input parameters. The program was verified through the design and construction analysis of the apartment project Connect 1 in Binh Duong, Vietnam. The settlement of piles, the lengths of which were reduced from 29.0 m to 16.5 m, ranges from 2.0 to 4.5 mm, indicating that the pile-soil behavior remains elastic. This demonstrates that the program has the potential to be used in practice, at least allowing engineers to understand the unified behavior of the pile groups.

AN EMPIRICAL STUDY OF THE BEHAVIOR OF RECYCLED AGGREGATE CONCRETE BEAMS FROM CDW IN HANOI, VIETNAM

Sun, 30 Jun 2024 00:00:00 +0000

The employment of recycled materials from construction and demolition waste (CDW) for mixing recycled aggregate concrete (RAC) is widely practiced in developed countries. In Vietnam, however, being a developing country with a rapid rate of urbanization, especially in major cities, the substantial amount of CDW generated is still mainly treated by landfilling. To promote the recycling of CDW, studies of the performance of structural members fabricated with recycled aggregates must be conducted, which are lacking in quantity in Vietnam. Adopting a standard experiment set up of reinforced beams, the study employed local recycled coarse aggregates in Hanoi, Vietnam, produced from crushed concrete and crushed brick (which is mixed with crushed concrete at controlled percentages) to conduct experiments to observe flexural behaviors with reference to equivalent natural aggregate concrete (NAC) such as cracking load, ultimate load, crack pattern, crack width, etc. The results showed that the ultimate loads were only reduced by less than 10% for all percentages of recycled coarse aggregate produced from crushed brick in the concrete mix, compared to the reference beams using NAC. However, the cracking loads of RAC beams were significantly reduced by 17.86% to 50.45% when increasing the content of crushed brick from 0% to 70%. Moreover, together with an increase in the number of flexural cracks, the deflections of RAC beams also increased with increasing content of crushed brick, demonstrating a reduction in the stiffness of the beams. These observations may serve as recommendations to structural engineers in Vietnam when designing flexural RAC members.

COMPARISON OF REDUCING SUGARS AS AGENT TO RETARD CORROSION RATES

Sun, 30 Jun 2024 00:00:00 +0000

This study reports the effect of adding sugars to prevent the corrosion of reinforcing bars. Various types of sugars, including reducing sugar aldose (sugar with an aldehyde group), ketose (sugar with a ketone group), and syrup with an expiration date, were used in experiments. These sugars exhibit remarkably similar skeletal structures and identical hydroxyl groups and hydrogen positions at carbon numbers 4–6. Inductively coupled plasma atomic emission spectroscopy (ICP-AES) and Tafel extrapolation were performed to reveal the effects of the sugars and their reductive abilities. ICP-AES showed that the concentration of dissolved iron in the fructose solution was about 1/270 of that observed in the blank, the lowest concentration of dissolved iron in this experiment, followed by waste syrup (WS). This demonstrated the reducibility of rebar by sugars. The ICP-AES results are consistent with the experimental results obtained using Fehling's solution and Benedict's reagent, as reported in a previous study conducted in 2021. The results of Tafel extrapolation showed no significant differences in corrosion rate. However, the current measurement methods are not optimal. Furthermore, molecular orbital calculations performed to evaluate the binding energies of the transition states of sugars to enediol structures confirmed that ketose was more reductive than aldose.

MECHANICAL PROPERTIES OF FOAMED CONCRETE (FC) USING HIGH-VOLUME FLY ASH

Yohans Sunarno, Parea Rusan Rangan, Ermitha Ambun, Miswar Tumpu — Sun, 30 Jun 2024 00:00:00 +0000

The production of foamed concrete (FC) using high-volume fly ash concrete (HVFAC) is an effort developed to minimize the adverse effects of construction activities on the environment. This initiative is associated with the ability of HVFAC to significantly reduce the use of Portland cement, including its lightweight nature, which requires a large volume of substitute additives. Therefore, this study aimed to evaluate the effectiveness of foam concrete produced using different HVFAC contents. The experimental process included the creation of five specimen variations. These included non-fly ash FC (FC0), which was used as the control with 100% Portland cement, and four variations, namely FC50, FC60, FC70, and FC80, produced using 50, 60, 70, and 80% fly ash of the total cementitious, respectively. Dry density and compressive strength were tested on the hard specimens at ages 7, 28, and 56 days, while the Initial Rate of Water Absorption (IRA) was conducted at the age of 56 days. The results showed that in 56 days, the increase in fly ash content in FC was inversely proportional to dry density and compressive strength values. However, the increase showed a direct proportionality to the water absorption value. FC produced with fly ash, which accounts for 50–80% of the total binder, can be efficiently used as an alternative infill wall material with substantial properties of being lightweight, cost-effective, and environmentally friendly, with acceptable technical specifications.