Department of Civil Engineering

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    Numerical Analysis of Pile Group Bearing Capacity Using Finite Element Method
    (Mekelle University, 2025-06-02) Lchya Gebre
    Pile group foundations are widely used to support heavy structures where individual piles cannot provide adequate bearing capacity or settlement control. This study focuses on the numerical analysis of pile group bearing capacity under axial loading using PLAXIS 3D v. 2013 a finite element software for geotechnical applications. The analysis investigates the load settlement behavior of pile groups embedded in clay, considering homogeneous and layer soil profiles, using the Mohr Coulomb constitutive model to represent soil behavior. To analyze the influence of a group of piles on bearing capacity and load transfer mechanism among them, the research includes the use of different pile configurations such as changes in the pile spacing, geometry, and even material properties. In behavior of the structures tested, contact elements have been used to model the integration of piles with soil whereas the model boundary conditions are properly placed so as to avoid displacement that is deemed arbitrary. Numerical results obtained from the simulations are validated against results obtained from traditional analytical methods like Meyerhof’s and Vesic’s equations. The key findings state that the pile group bearing capacity is highly associated with the multiplier of pile spacing, and interaction between the pile and soil. The investigation also underlines the necessity to employ modern numerical methods, like PLAXIS 3D, to solve complex interaction of soil and structure that is common place in the analytical approach. This research offers some crucial information to the geotechnical engineers as aid in development and analysis of pile foundations to be more precise and more reliable. The results highlighted the importance of combining classical techniques with numerical ones in order to achieve more secure and more competitive design concepts for the foundation.
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    Assessment of the Performance and Challenges of Public Procurement of Works in Semera, Afar National Regional State
    (Mekelle University, 2025-09-25) Ali Amin Ibrahim
    Public procurement is a pivotal mechanism linking project aspirations to the delivery of quality infrastructure. In Semera, Afar National Regional State, despite substantial investment in public works, procurement outcomes have often fallen short of expectations. This study assessed thirty public works projects implemented between 2018 and 2023, revealing systemic inefficiencies, delays, and quality shortfalls. Only 58% of projects complied with national procurement guidelines, procurement cycles averaged 6.5 months, and cost overruns affected 40% of projects, with an average escalation of 18% above contract values. Time and quality performance were also suboptimal, with less than half of projects completed on schedule and only 60% meeting technical standards. The analysis identified several institutional and market-related challenges undermining procurement performance. Capacity constraints were significant, with 72% of procurement staff lacking formal training and high turnover reducing continuity. Planning weaknesses were widespread, as 65% of procurement plans were delayed or incomplete, often without adequate market analysis. Transparency and accountability were insufficient: only half of tenders were openly advertised and nearly a third lacked complete bid evaluation reports. Market limitations further constrained performance, with an average of only three bidders per tender and contractor capacity often insufficient, resulting in project suspensions or abandonment. The consequences of these challenges were evident in persistent cost overruns, project delays, and compromised quality, particularly in essential infrastructure such as schools, roads, and health centers. Stakeholder confidence in procurement was low, with 68% rating performance as ineffective. These systemic weaknesses reduce the value for money and delay the delivery of public services, highlighting the urgent need for institutional reforms and operational improvements in public procurement practices in Semera. To address these gaps, the study recommends capacity building, improved planning, enhanced transparency, stronger oversight and accountability, and support for local contractors. Implementing these reforms will enhance efficiency, cost-effectiveness, and quality in public works, promoting sustainable economic development in Afar.
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    Assessment and Design of Suitable Flood protection work at the Downstream of Gereb Burka River, Southern Tigray
    (Mekelle University, 2025-09-05) TESFAY HAILU
    Flooding along the downstream section of the Gereb Burka River in Southern Tigray's Raya Azebo Wereda near Mekoni city poses significant risks to communities and infrastructure. This study proposes flood defense measures to mitigate these hazards through gabion structural interventions. Hydrological analysis was conducted using rainfall data from the Maichew meteorological station (1993–2019), applying methods for missing data estimation, adequacy testing, and outlier detection. The Soil Conservation Service Curve Number (SCS-CN) method was employed to estimate runoff, considering land use/land cover and hydrologic soil groups (CN = 86 for AMC III). Peak discharge was calculated as 234.5 m³/s for a 25-year return period, with a probable maximum rainfall of 80 mm derived from log-normal distribution analysis. Gabion structures were identified as the most suitable flood defense mechanism due to their cost effectiveness, adaptability, and compatibility with the erosion-prone, semi-arid conditions of the region. A detailed stability analysis confirmed the structural integrity of the proposed gabion design, with factors of safety against overturning (>4.1), sliding (>1.6), and bearing capacity failure (>7.6) meeting engineering standards. The design includes a 2.2 m-high gabion wall with a 73 m waterway width. This research provides a practical solution for flood mitigation in the study area and serves as a reference for similar projects. Recommendations emphasize regular maintenance of flood defenses, community awareness programs, watershed reforestation, and further studies on sediment management to enhance long-term resilience. The project underscores the importance of integrating hydrological and geotechnical analyses in flood protection planning.
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    Assessment and evaluation of hydraulic parameters in Raya irrigation pumping wells
    (Mekelle University, 2025-09-05) Samiel Gigar
    The Raya well field located in the northern part of Ethiopia, southern part of Tigray region and have raised concerns with respect to the ability of the aquifer system to sustain production. As the aquifer of Raya well field in particular is heavily used in this area, understanding the hydraulic parameters of the area is essential for efficient sustainable management of the groundwater resource. An overview of the hydraulic parameters estimated for the 22 pumping irrigation wells in the study clearly show strong evidence of inappropriate estimation. Thus, this study was conducted to identify the possible miss-interpretation of the observed time-drawdown, step drawdown, time residual drawdown-based hydraulic parameter estimation. After data quality checking, appropriate data correction for partial penetration, well loss and unconfined aquifer were conducted. Then the standard methods like Theis curve fitting, Cooper-Jacob methods for time drawdown data & Theis recovery method for time-residual drawdown data were used for parameter estimation. Beside Aquifertest v8.0 software was also used to verify the results of the original study. Evaluation and analysis result showed that out of the 22 well analyzed, 15 transmissivity values used in the well yield estimate were overestimated (0.22 up to 29.23 percent) and 6 underestimated (0.26 up to 1700.72 percent) the other one well has not stated transmissivity value, such highly overestimated transmissivity value misleads the designers & operators in fixing the well yield, 15-25% cost overrun, Poor water supply reliability, planning inequity and trust erosion with the client or society and reduce the life span of the pumping wells by 26-62 percent. Additionally, from 22 pumping wells 18 or 81.81 percent out of the total sample wells have not efficiency stated in the design documents. The minimum efficiency of irrigation wells should be 60%, considering this minimum irrigation wells efficiency limit 3 pumping wells have efficiency greater than 60 percent this is around 13.63 percent the others 19 pumping wells have less than 60 percent efficiency, this is around 86.36 percent. The storativity of unconfined aquifer is 0.1-0.3 and the storativity of confined aquifer is 0.005-0.00005. data from Tigray office of water resources and energy shown that the storativity of the 13 wells are far away from the range whereas 2 wells are slightly out of the range. The rest 7 wells have not storativity stated in the document. results from this research computations shown that the storativity of the 14 wells are far away from the range, whereas 7 wells are slightly out of the range. The rest 1 well falls within the range or accepted. the reason behind this large error in storativity value is the wells are only pumping or production wells, for accurate and precise storativity computation an observation well is very mandatory. The recommendation for the less efficiency is to Reduce the pumping rate or Optimize Pumping Operation. Results also shown that most of the irrigation pumping wells fall on the category of class of transmissivity magnitude “II” and fall on the “high” designation of transmissivity magnitude. a well pumped for 18 hours per day and for 120 days in a year it can lead to cumulative land subsidence from 0.009 meter or 9 mm up to 0.056 or 56 mm per year. Therefore, in this evaluation it is recommended to conduct multiple well test to determine the actual hydraulic parameters of the aquifer in order to obtain the safe yield of the wells which is intended to prolong the productivity of the aquifer and to delay excessive loss of saturated thickness.
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    Investigating Causes of Failure of Diversion Structure for Irrigation Scheme. (Case Study; May Timket River Diversion, Central zone of Tigray)
    (Mekelle University, 2025-09-05) Nigsti Teklay
    Small scale irrigation schemes are a key component of the Ethiopian government's food security strategy, Intended to boost agricultural productivity in smallholder farming. Over the past years, numerous schemes have been designed and implemented in the Tigray Region. While some have been successful, others have failed to fulfill their intended purposes. This research focuses on investigating the causes of failure of diversion headwork’s used for irrigation, with specific emphasis on hydrological, hydraulic, and structural design issues. The study centers on the May Timket River Diversion, located in Kola Tembien Woreda. Various data sources were collected and analyzed to identify the primary causes of failure in the May Timket irrigation scheme. ArcGIS was used to delineate the watershed of the study area. Therefore, peak flood discharge was estimated to be 367.66 m^3/s by using the Tekeze Basin method for a 50 year return period. The previous peak flood was 203.18 m^3/s. This difference shows that the causes of failure of the Diversion is mainly due to underestimation of peak flood discharge.in addition there were a problem on material they used; the stone used for masonry is from the river which is rounded and smooth. This makes loose bondage on each other. Therefore the remedial measure to be taken to solve the problem is redesigning the diversion weir based on the new peak flood that found through this study and reconstruct the weir structure using gabion inserted concrete, and gabion inserted hard core to strengthen the structure and protected with proper energy dissipation by constructing stair like structure at downstream of the weir to dissipate energy and downstream scour protection. Strict quality control during construction and regular maintenance are also essential to ensure long term stability and performance.
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    Improvement of Weak Sub base Materials Performance by Stabilization with Sand: A Case Study Wukro – Tsigereda Gravel Road.
    (Mekelle University, 2025-07-22) Asfaw Berhe Gebreslassie
    Road pavements commonly consist of several layers of various materials and thickness. The performance of a pavement depends on the quality of its subgrade and sub base layers. There are many soil stabilization methods to gain the required engineering properties. These methods range from mechanical to chemical stabilization. Chemical treatments are relatively expensive to be implemented in most developing countries and the best way is to use locally available materials with relatively cheap costs and affordable. A laboratory experiment carried out in this study which aimed to highlight the physical mechanisms of improvement of the weak sub base materials performance by Stabilize with sand. On the collected weak sub base soils from Bellesa quarry sites, Tsabat quarry sites and Tseartet quarry sites a laboratory tests such as Atterberg’s limit test, Grain Size Analysis, Compaction test, CBR and CBR Swell test were done for weak sub base and sand materials from river Suluh a laboratory tests such as Specific Gravity, Grain Size Analysis and water absorption for a sand. The result of the analysis reveals that the weak sub base materials were investigated and examined by mixing with sand. Thus, the mixtures used in the stabilization of weak sub base materials with sand were 0%, 10%, 20%, 30% sand content by weight. In conclusion the result shows that the addition of 0%, to, 30% sand content in to the weak sub base materials improves the CBR (%) values of weak sub base materials to Bellesa quarry sites from 20.3 to 39.7, to Tsabat quarry sites from17.0 to 32.1 and to Tseartet quarry sites from 9.8 to 31.7 respectively. The maximum dry density (g/cm3) of weak sub base materials are maximized to Bellesa quarry sites from 1.868 to 2.058, to Tsabat quarry sites from 1.14 to 2.156 and to Tseartet quarry sites from 1.775 to 2.036 respectively. And, the liquid limit (%) of weak sub base materials are minimized to Bellesa quarry sites from 24.6 to 19.65, to Tsabat quarry sites from 27.76 to 19.03 and to Tseartet quarry sites from 33.14 to 19.96 respectively and the other results are changed the result. This study relates to soil investigations data collected from worked laboratory. The provision of improved layer avoids the necessity of an extraordinary thick sub-base, and provides an adequate working platform for base course and surfacing compaction as well as reduces the risk of damage to the sub base during construction. The study objective was to identify variables that mainly contribute to the type, extents and severity level of the pavement distresses.
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    Developing a Predictive Model for CBR Value Using Soil Index Properties: A Case Study of the Mekelle Asphalt Road Project
    (Mekelle University, 2024-04-15) Million Abrha Weldegeorgis
    California Bearing Ration (CBR) value is an important soil parameter considered as main design input in the design of flexible pavements and runways of airfields. The design of pavement thickness determined depending on the strength and stability of sub-grade materials are evaluated before construction of pavement by using CBR test. And Index properties of soil are properties which are used to characterize soils and facilitate identification and classification of soils for engineering purposes. However, in a large-scale road project soil properties vary from region to region and season to season as it appears naturally. Thus, developing empirical equations specific to a certain region and soil type could be considered nearly as good insight of soil behavior. This study was conducted to developing a predictive model for CBR value using soil index properties of soils in the case study of the Mekelle Asphalt Road Project. The study was carried out using 27 samples collected from SUR Construction PLC Mekelle Asphalt Road Project. And test procedures were carried out based on the (ASTM) and (AASHTO) at Mekelle Asphalt Road Project Laboratory. This study tries to use a single linear regression model and multiple linear regression models to characterize the strength of the subgrade soils from the soil index properties using a statistical method. The laboratory test results and statistical analysis were carried out using Microsoft Excel and SPSS software. To develop the intended correlation and regression analysis CBR value at different blows such as 10, 30 and 65 blows were considered as dependent variable. And index properties of soil such as percent passing 2.0, 0.425, and 0.075 mm (sieve No. 10, 40, and 200) sieve size, LL, PI, OMC and DD at points 10, 30, 65 blows were considered as independent variables. From the regression analysis result, the equation and coefficient of determination developed are:  CBRat 10 Blow = -7.99 - 0.024LL - 0.025PI + 0.187P10 - 0.133P40 + 0.027P200 - 0.025OMC + 2.68DDat 10 blow, R2=0.913, adj R2=0.881  CBRat 30 Blows = -3.1 - 0.058LL + 0.006PI + 0.133P10 - 0.092P40 + 0.008P200 - 0.055OMC + 2.87DDat 30 Blows, R2=0.965, adj R2=0.953  CBRat 65 Blows = -3.301 - 0.113LL + 0.054PI + 0.085P10 - 0.004P40 + 0.050P200 - 0.088OMC + 1.373DDat 65 Blows, R2=0.928, adj R2=0.902
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    Investigation on Practice of Ethiopia Building Regulations and Codes of Standard in Mekelle City Municipality - Tigray
    (Mekelle University, 2025-07-24) Mebrahatu Tadele
    Since 1983, Ethiopia has established three Building Codes of Standards, along with national building regulations, a building proclamation, building directives, a construction policy, training institutions, a product standardization agency, and directives for licensing contractors and consultants. However, the proper enforcement of these laws, regulations, and standards remains questionable due to poor implementation, inadequate monitoring, and weak oversight by relevant authorities. Additionally, the compatibility of these regulations, policies, codes, and standards with the country's economic development, existing technologies, and available workforce is debatable. As a result, the country continues to experience significant loss of life, property damage, and economic setbacks. This research project aims to investigate the implementation of Ethiopia’s building regulations and codes of standards in the Mekelle City Municipality, Tigray. A review of relevant literature provides a foundation for the study, and data is collected through questionnaire surveys and records reviews. The data is then analyzed using SPSS v.20 software. The study reveals that out of 75 targeted respondents, 61 (86.7%) participated, including contractors, consultants, building officials, and regional professionals. The findings highlight a significant gap between established building regulations and actual practices due to inadequate inspections and weak enforcement mechanisms. The lack of a centralized authority and clearly defined procedures further contributes to non-compliance. Key issues identified include unclear professional responsibilities, insufficient regulation of building materials, and a lack of standardized practices. The failure to implement Ethiopian building regulations and codes of standards stems from multiple factors, including a lack of awareness, weak enforcement mechanisms, corruption, economic constraints, rapid urbanization, political instability, cultural preferences for traditional practices, and inadequate infrastructure for monitoring compliance.
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    Investigating Challenges of Construction and Demolition Waste Management, in the Case of Mekelle, Tigray
    (Mekelle University, 2025-07-18) Kiros Hailemariam Mesele
    With rapid urbanization and economic growth, All the activities, new construction, renovation, and demolition of buildings and structures generate huge amounts of waste, which require reduction in generation and proper management. Nevertheless, due to several barriers and constraints this could not be implemented. The purpose of this study was investigating challenges of construction and demolition waste management in Mekelle construction projects. Based on this objective, the factors that contribute waste, effects of C&DW, current construction waste management practice and major challenges of C&DW management have been investigated. The study used semi structured interview and questionnaire survey for data collecting techniques, and relative importance index for descriptive data analysis. The result of the study shown the improper material handling and storage, poor supervision, lack of skilled man power and late design changes are the most contributing factors to waste generation. Whereas, Project cost overrun, Environmental Pollution, Reduction in profit, Resources depletion and public health and safety risks are the main effect of C&DW. In the current construction waste management practices, the governing strategies i.e. waste reduction and proper management were not effectively implemented. Furthermore, the following main challenges were identified in this research. The challenges are; Improper planning & waste management practice, Ineffective waste management plan, Insufficient waste management training programs, Poor supervision practice, Lack enforcement of regulations, Absence of training on waste minimization strategies for construction firms, insufficient legislation & regulation, Lack of Government incentives, Low Concern for socio-economic and environmental effect of wastage, Resistance to change traditional management practices, Poor coordination among construction stakeholders, Believing waste not a problem on site, High cost with low quality of recycled materials, Lack of demand for recycled materials, and High cost of waste disposal. The study also recommends that Managing C &D Waste needs a serious attention from all the stakeholders involved throughout the construction process.