Journal of Engineering Geology

On-site utilizing demolition waste as fine recycled aggregates to produce non-structural foam concrete, a sustainable approach

Nima Heidarzadeh

This study aims to propose a novel practical procedure to use demolition waste as recycled concrete. Foam concrete with a density of 960 (kg/m³) was produced using fine-grained demolition waste. Instead of using traditional aggregates, two groups of demolition wastes, with gypsum (WG) and without gypsum (W), have been used in the mixture of the concrete at weight percentages of 30, 70, and 100. The applied experiments were flow table, unconfined compressive strength (UCS), and scanning electron microscope (SEM). Results showed that increasing the percentage of the replaced construction waste decreases the flow rate of the samples due to their high-water absorption. Moreover, the measured wet density of the recycled samples varies from 906 to 1022 (kg/m³). By replacing construction waste with sand by 30%, 70%, and 100%, the 28-day UCS respectively decreases by 36%, 23%, and 19.9%. The highest UCSs were observed in the S0W100 and S0WG100, with the average 28-day UCSs of 2.38 and 2.55 (MPa), respectively. Then, the amount of gypsum waste (6.6%) has no significant effect on reducing the UCS. The SEM results also showed that the average percentage of the pores resulting from the use of foam reagent has decreased by 17.6%, 18.6%, and 21.3% in samples with 100%, 30%, and 70% replacement of recycled materials, respectively. The present study suggests direct use of demolition wastes as produced before disposing of them.

Evaluation and ranking of rainfall estimation database data, case study: Khuzestan Province, Iran

Arash Adib

Precipitation is one of the most important climatic variables, and due to its direct role in water resources, agriculture, and human livelihoods, its accurate assessment is of great significance. In recent years, gridded precipitation datasets, including station, satellite, and reanalysis data, have found widespread application due to their easy accessibility, lower cost, suitable spatial coverage, absence of missing data, and long temporal duration; however, examining their accuracy and validity is essential for scientific use. In this study, five precipitation datasets, namely APHRODITE and CRU (raingauge-based), PERSIANN-CDR (a combination of satellite and raingauge), and NCEP CFSR and ERA5 (reanalysis-based), were evaluated using the indicators R², NSE, NRMSE, BIAS, POD, FAR, and CSI, in comparison with data from 9 synoptic stations in the Khuzestan province. Since the number of indicators was large, the TOPSIS multi-criteria decision-making method was used for the final ranking of the datasets at each station. The results indicated that APHRODITE, CRU, and NCEP/CFSR provided the best performance, with APHRODITE exhibiting the highest agreement with observations across all stations; its average indicators were POD=0.756, FAR=0.290, and CSI=0.692. It was also found that some datasets may have lower accuracy in estimating precipitation amounts but demonstrate suitable performance in identifying rainy days. Therefore, the selection of a precipitation dataset should be based on the intended application.

Assessment of water seepage risk in the Sarploe Zahab water transfer tunnel (T4) using analytical, empirical, and numerical methods

Mashalah khamehchiyan

One of the major challenges in tunnel engineering is the estimation and prediction of water inflow into tunnels. Although numerous methods have been proposed to evaluate hydraulic behavior and to estimate the permeability of soil and rock masses depending on their geological structures, these methods still lack sufficient accuracy and certainty. Therefore, in this study, the amount of water seepage into different sections of the Sarploe Zahab water transfer tunnel (T4), as part of the Sirvan river water transfer project to the tropical regions of Kermanshah and Ilam provinces, was evaluated using analytical (Goodman, Karlsrud, and El Tani), empirical (SGR and TIC), and numerical (SEEP/W) methods. The tunnel has a total length of 3.4 km, a diameter of 8.6 m, and inlet and outlet elevations of 552.51 m and 549.50 m above sea level, respectively. The results indicate that the water inflow into different tunnel sections varies from <1 to 161 L/s based on analytical methods, from <1 to 8 L/s and from <1 to 35 L/s according to the SGR and TIC empirical methods, respectively, while values ranging from <1 to 19 L/s are obtained from numerical modeling. Furthermore, the hydraulic flow components, the influence of the river on water inflow into the tunnel, and the differences resulting from considering layer-by-layer hydraulic conductivity instead of equivalent hydraulic conductivity were modeled. Finally, by correlating the results with the geological conditions of the study area, it was determined that water inflow may pose a risk at chainages 0+239 and 1+829, and these sections of the tunnel should receive special attention during construction.