— Recent urbanization of central parts of Addis Ababa has necessitated the use of deep excavations for the foundation of high - rise buildings and related infrastructure projects. The conditions of the subsoil, the safety of neighboring structures, groundwater condition s, experience by contractors , working space, the effect of vibration, and noise must be considered for the choice of deep excavation support system. Besides, e conomic factors, local availability of equipment, and technical staff are also governing factors for choosing an appropriate shoring technique . The study focused on the major construction methods and techniques of shoring works in Addis A baba, Ethiopia. Only f our projects utilized shoring construction techniques from the total number of high -rise buildings available in the City. The target population included a minimum of twenty respondents from the four construction sites constructed arou nd Beherawi, Lideta sub -city in Addis Ababa. Two of the projects were supervised by S pecialists from Varnero Foundation and Meseret Foundation PLC . Primary and secondary data are gathered to support the objective of the study . All the frequency distribution, Reliability, and Pear son correlation were analyzed usi ng SPSS. All groups of factors that affect shoring construction were ranked using the Relative I mportance Index (RII) . Results indicated that geotechnical investigation , building type, and excavation depth were the major factors with an RII value of 0.89 and 0.86, respectively. Besides, the analys es showed that were strong correlations between the different factors with in each group of factors in undertaking the shoring construction . Hence, it is suggested to take a deep and detailed sub-soil investigation to determine the suitability of shoring materials , appropriate construction methods, and technique s. Keywords – Deep Excavation, Foundation Work, Geological N ature, High -Rise Building , Shoring Technique. I. INTRODUCTION Urbanization is a trend that has been growing worldwide since the middle of the last century. Large metropolitan cities in Europe, North America, and the South East Asia region have evolved this trend. Fast population growth, limited land resources, high rise buildings, sophisticated and complex infrastructure needs have caused extra pressures for deep excavation undergrou nd construction. Environmental and social constraints such as limitations on noise levels, vibration, and soil movement in nearby or neighboring existing stru ctures have been considered [1]. Addis Ababa was founded as Ethiopia's official capital city in 1886 by Emperor Menelik II and his wife, Empress Taytu Betul; the capital holds 527 s quare kilometers of the area of Ethiopia. Addis Ababa consists of 3,384,569, with a growth rate of 4.37%, based on the 2007 census. The number may become inaccurate when recording and underestimated the city population, and the population is estimated to b e around 4,793,699 in 2020 according to the world urbanization prospects. The population density of the City is estimated to be near 5,165 individuals per square kilometers available [2]. Throughout the century, the rural expansion is associated with movement and displacements of the population from the rural countryside areas to Addis Ababa were dramatically increased. It is associated with poverty issue and lack of infrastructure for an ever-increasing number of people; because of this and other fact ors, Addis Ababa experienced a considerable rise in land prices, the emergence of multi -story buildings as a norm with an increasing number of floors from two and three stories to higher buildings exceeding twenty stories. Due to land scarcity at these cit y centers, deep excavation for the underground construction of multiple basements is now normally considered [3]. When space is available, the most economical way to build a permanent basement is to construct an open cut excavation foundation. This require s a sufficient right to construct safe slopes and access to excavation, dewatering, and backfill construction expertise [4]. Limitations associated with an open cut solution typically happened in construction sites with restricted laydown areas far away fr om the building, restricted crane access, and dewatering problem. The latter is often associated with detrimental settlement s of surrounding properties [5]. In the central business district area of Addis Ababa, particularly around "Senga Tera, Beherawi," several high -rise buildings are being constructed that needs a deep excavation for structural and functional purposes. As a result of these, it is important to practice shoring technology to protect the adjacent building s and the surrounding soil from possible collapse. Shoring renders a support system for trench faces to prevent soil movement, underground utilities, roadways, and foundations. Shoring is used when the cut's location or depth makes sloping back to the maximum allowable slope impractical and within a Journal of Xidian University VOLUME 14, ISSUE 10, 2020 ISSN No:1001-2400 http://xadzkjdx.cn/ https://doi.org/10.37896/jxu14.10/074 692 confined space. Shoring design can be a challenging task. The designer has to contend with many unknowns and factors that influence the excavation shoring [6]. Due to the construction industry's different emerging technology and complexity, many infrastructures become high -rise building and high way pavement. Much of those structures were constructed around the CBD area of Addis Ababa. Most of the CBD areas are confined and densely populated. For this reason, it is difficult to have a lar ge plot of land to construct those high -rise buildings. Moreover, the excavation is being conducted with a small land plot using slope bracing as a conventional system, leading to damage to adjacent buildings, highway, and Underground utilities. Hence the use of shoring technology to solve these problems is highly valuable. However, in Ethiopia, shoring work is generally performed with a small number of specialized firms in foundation work. However, the need for advanced technology, technique, cost, and higher deman d comes from the fast -growing building construction project. Due to this case, those involved in shoring work may suffer capacity problems to cover the whole projec t, making the project delay and fail. Considering these problems, the study investigates the main factors and challenges the local firms faced to ad apt to this Ethiopia technique. II. RESEARCH METHODS A. Study Area Addis Ababa is Ethiopia's capital city and found in the western margin of the Ethiopian Rift valley. Its geographical coordination is 90 0' 19.4436" N, 380 45' 48.9996" E and 2355m above sea level. The study area has been located under "Lideta sub-city" around "Beherawi," Addis Ababa, Ethiopia [7]. B. Sample Size and Selection The purposive sampling method was utilized in selecting construction sites . The samples were purposively selected from the Addis Ababa construction sites. Now a day the construction sites found in the town is mostly high rise building. Besides , only three licensed foundations specialists have been practicing the shoring construction technique in Ethiopia. Due to the above reason , all respondents were taken from four construction sites, which was being constructed under three construction firms, two under anchor foundation specialists, one under the Varnero foundation. In contrast, the remaining is from Meseret construction firms. In the case of the research population, it did not mean that all stakeholders are possible respondents for the questionnaire. Rather the questionnaire was distributed to engineers & other professionals who know the concerned construction projects during the specified time. The minimum number of respondents is calculated based on Slovin's sampling formula (Yemane, 1967). n=N 1+N(ⅇ)2 …………………………………………………………………………… (1) Where: n is the sample size N is the popula tion size e error margin / margin of error, a 95% confidence level was taken and e = 0.05 So, for 25 stakeholder’s respondents: n =20 is taken C. Data Collection Process The study has used a different data source to attain its objective. In connection with this, Literature reviews were conducted to develop a conceptual foundation for the study. Simultaneously, through the l iterature reviews, the research questions were identified. The literature review provided the questionnaire and interview design root, distributed to professionals involved in the construction companies. A questionnaire is designed based on the literature review's collected data considering various factor s that affect shoring construction in the deep excavation . Similarly, secondary data sources were collected based on the case study on Ethiopia's different shoring work techniques. Correspondingly, it is used as a reference and as an input to assess the cu rrent trend. Lastly , a desk study on c ase studies, questionnaires, interview, and field survey has been cross -checke d to obtain the required result D. Data Analysis The results of the questionnaires are analyzed using statistical techniques. All the frequency distribution, Reliability, and Pearson correlation were conducted using SPSS [8]. All groups of factors (i.e., variables) that affect shoring construction were ranked using the relative importance index (RII). The data were analyzed through statistical tools such as: i. Statistical Pa ckage for Social Science (SPSS) According to the contributing level, the questionnaires were prepared based on the Likert scale of five ordinal measures from 1 to 5 (very low effect to very high effect [9]. Frequency distribution, which shows the frequencies of observation of each response to each variable, was investigated using SPSS and used to analyze some questions. The level of measurement must be ordinal Journal of Xidian University VOLUME 14, ISSUE 10, 2020 ISSN No:1001-2400 http://xadzkjdx.cn/ https://doi.org/10.37896/jxu14.10/074 693 scales. The ordinal scale is a ranking or rating data that normally use integers in increasing or decreasing order. The numbe rs are assigned to the agreement or degrees of influence (1, 2, 3, 4, and 5) do not indicate that the i ntervals between scales are equal, nor do they indicate absolute quantities. They are merely numerical labels. Based on this scale, the researcher has the following table: TABLE I A RATING SCALE FOR A S IGNIFICANT LEVEL OF FACTORS Significance Level Extremely Significant Very Significant Moderately Significant Slightly significant Not Significant Scale 5 4 3 2 1 Likert scale is important to know respondents' feelings or attitudes about something and is utilized for the data analysis. The respondents must indicate how closely their feelings match with the question or statement on a rating scale. MS = ∑[𝑓∗𝑆] 𝑁………………………… ………………………… …………………(3) Where: MS = Mean Score f = Frequency of responses for each scores. S = Scores given to each factor. N = Total No. of responses concerning each factor One of the most common methods used to measure the relat ionship between variables is Spearman Rank's Correlation Coefficient method and Pearson's correlation. In this study , Pearson's correlation method is used since it’s often used to evaluate relationships involving ordinal values. ii. Relative Importance Index (RII) The contribution of each of the factors to overall delays was examined, and the ranking of the attributes in terms of their criticality as perceived by the respondents was done by use of Relative Importance Index (RII), which was computed using an equation and the results of the analysis are presented in Tables. To determine the ranking of different factors from responden ts' viewpoint, the Relative Importance Index (RII) was computed using the Equation below [10]. RII = ∑𝑊 (𝐴 𝑋𝑁)…………………………………… ……………………… ……. (4) Where: W = Weightage given to each factor by the respondents A = Highest weight (i .e., 5 in this case) N = the total number of respondents Finally, after the questionnaires' results were analyzed using statistical techniques, it is used to form recommendations for further researc h. This was followed by thorough discussions to draw a conclusion and forward recommendations based on the study's findings. III. RESULTS AND DISCUSSION A. Assessment on Current Shoring Construction Techniques In this part of the study, the study found out the current trend on shoring construction in line with the first specific objective. Case studies were collected from four building construction projects in the CBD areas of Addis Ababa, Ethiopia, those have be en under execution from the year 2010 E.C. to 2012 E.C. The data were collected from archival documents, Discussion with participants on the project site, and data from the parties conducting the shoring work. The following information was gathered from the open -ended questionnaires distributed t o the stakeholders in the study area. This subtitle of the study is described like the steps used to carry out shoring construction. A.1 Drill and Pour Concrete into Shoring Pile After soil investigation and design, the first activity is drilling and casting a pile into excavation depth around the propo sed site's perimeter. The s teps to undertake the process are: Adjust the piling machine on the pile axis and haul with the auger to the drilling place & Start drilling until the auger is fill ed, Swing to the uploading area, then Swing back to the top of the hole after that Repeat the above two steps until the pile is completely drilled, start erecting rebar cage using a crane using a funnel for dry method and tremie for wet method start pouring the concrete into the shoring pile care must be taken to avoid segregation and Finally, after this process completed and the concrete cure, start excavation. Journal of Xidian University VOLUME 14, ISSUE 10, 2020 ISSN No:1001-2400 http://xadzkjdx.cn/ https://doi.org/10.37896/jxu14.10/074 694 TABLE II BAR DIAMETER AND SPACING OF ANCHOR PILES From the above table , 50% of the respondents agree that the diameter of anchor piles should be 80cm2, and 60 of them agree 1.80m is enoug h for spacing in the study area . i. Excavation The second activity in shoring construction is excavation; it is carried out in a manner illustrated in the figure below to t he excavation depth. Figure 1: Excavation ii. Tie back anchorage Tie-back anchorage technique a general term in this technique drilling of piles, grouting, stressing is included. The inclination angle for drilling a pile varies as the nature of soil and depth of e xcavation change from the questionnai re survey. TABLE III TABLE 4. ANGLE OF INCLINATION FOR TIE BACK CONSTRUCTION Drilling Angle Frequency Percentage 200 2 10% 250 6 30% 300 4 20% 350 8 40% Total 20 100% From the above table, 40 % of the respondents execute their work with 35% the inclination angle. The recommended design standard of tie back is 10 -40% of inclination, so all the results are within the standard. iii. Mesh for Shotcrete Reinforcing in Shotcrete is designed like conventional concrete, and bars must be sized a nd positioned to minimize interference with shotcreting. The common diameter of bars and spacing are summarized as follows based on the questionnaire survey. Parameter Frequency Percentage Diameter (cm2) 60 6 30% 70 4 20% 80 10 50% Spacing (m) 1.50 4 20% 1.70 4 20% 1.80 12 60% Journal of Xidian University VOLUME 14, ISSUE 10, 2020 ISSN No:1001-2400 http://xadzkjdx.cn/ https://doi.org/10.37896/jxu14.10/074 695 TABLE IV BAR DIAMETER AND SPACING OF SHOTCRETE Parameter Frequency Percentage (%) Diameter (mm2) Horizontal Bars 10 12 60% 12 8 40% Total 20 100% Vertical Bars 8 6 30% 10 14 70% Total 20 100% Spacing (cm) 1.50 11 55% 1.80 5 25% 2.00 4 20% iv. Shotcrete Construction Shotcrete is the generic name for cement, sand, and fine aggregate concretes, which are applied pneumatically and compacted dynamically under high velocity by compressed air [11]. There are two techniques of shotcrete construction used in Ethiopia. These a re:  Wet-mix shotcrete  Dry mix shotcrete Figure 2: Wet and Dry shotcrete process B. Analysis of Factors Affecting Shoring Work Construction The results of this part of the study are directly related to the study 's second specific objective. It includes the Reliability of research instruments based on SP SS scale analysis and combined Relative Importance I ndex (RII) of ranking factors affecting the shoring work construction during deep excavation. According to all and each participan t's respectively and correlation coefficients between responses of the participants. B.1 Reliability of research instruments Reliability means consistency. It is the degree to which an instrument will give similar results for the same individuals at different times. It is the degree of uniformity of the results obtained from repeated measurements. The data quality has been assured and measured through an internal validity instrument into correct research instruments to measure the variables during the dat a collection procedures. Besides, data consistency was checked using a reliability test (Cronbach‟s Alpha methods). According to Sekaran (2010), Reliability less than 0.6 is considered poor; those in the 0.7 range , acceptable, and those above 0.8 are good [12]. WATER CONCRET E Journal of Xidian University VOLUME 14, ISSUE 10, 2020 ISSN No:1001-2400 http://xadzkjdx.cn/ https://doi.org/10.37896/jxu14.10/074 696 TABLE V CRONBACH’S ALPHA COEFFICIENTS OF THE VARIABLES No. Group of Factors No. of Items Cronbach’s Alpha Coefficients 1 Selection Criteria Factors 5 0.712 2 Geotechnical Investigation 4 0.763 3 Design 7 0.806 4 Construction Techniques 7 0.742 5 Economy 4 0.708 The table above indi cated the value of the Cronbach’ s Alpha for the group of factors was above 0.7, which explains the scale's acceptability for further analysis. B.2 Shoring Type Selection Criteria In this category, around five factors were identified from the literature reviews that affect the shoring type selection process. Based on the Relative Importance Index (RII) and Pearson correlation value results , table VI and figure 3 displayed the results of participants' and RII and the rank of factors affecting the shoring type selection process. TABLE VI RANK ED OF SELECTION CRITERIA FACTORS No. Factors Frequency RII Rank 1 2 3 4 5 1 Subsoil Condition 0 0 1 9 10 0.89 1 2 Depth of Excavation 0 0 4 11 5 0.81 2 3 Space to a nearby structure 0 0 9 10 1 0.71 3 4 Cost 0 2 12 6 0 0.64 4 5 Technology 0 8 10 2 0 0.54 5 Figure 3: Selection criteria factors Based on the combined Relative I mportant Index and rank ing, as shown in figure 3, the critical and top -ranked factors considered during shoring type selection are discussed below. Subsoil condition became the first main factor that extremely affected shoring type selection criteria with a relatively impo rtant index value of 0.89. The nature of soil highly affects the type of shoring structure to be constructed on the proposed site. As the researcher describes in the literature part of the study, the selection process of earth retaining structures differs as soil layer changes. The excavation depth has been the second main factor that affects the shoring type's selection process extremely with a relatively important index value of 0.81. This is because of the depth of excavation of a structure is governed by several fa ctors, including the func tion and type of a building, Availability of excavation equipment, Availability of time. Because of this and other factors, excavation depths have highly affected the type and methods of shoring. Nearby utilities and cost have been the third and fourth fac tors with a relative importance index value of 0.71 and 0.64, respectively, and affect significantly. There is a higher demand for land for construction in most CBD areas, leading to a hi gh- rise building in small land plots. Excavation work in a small plo t of land may seriously affect the stability of any portion of a building structure at or adjacent to the proposed excavation location, which can lead to structural failure or collapse. Cost s of shoring work also affect the selection criteria because it is a machine intensive works which need expensive equipment to rent as well to own. 40% 30%15%10%5%Percentage of Factors subsoil Condition Depth of Excavation Nearby Structure Cost TecnologyJournal of Xidian University VOLUME 14, ISSUE 10, 2020 ISSN No:1001-2400 http://xadzkjdx.cn/ https://doi.org/10.37896/jxu14.10/074 697 Technology has been the last factor that affects moderately, with a relative importance index value of 0.54. Shoring is a new technique of earth retaining structure in Ethiop ia, and it needs advanced equipment, skilled labor that best feet with the techniq ues in which shoring requires. Generally, in this study, the nature of the soil, depth of excavation, space of nearby structures, cost, and technology affect the selection of excavation support systems. B.3. Geotechnical Factors A subsurface investigation is a process of collecting information and evaluating the site's conditions to design and construc t the foundation for a structure, such as a building, roads, etc. The geot echnical site investigation's effort and detail are mandatory to obtain sufficient and correct site information to select and design a shoring structure. Table s VII and VIII showed the participants' RII, the rank, and the Pearson correlation of geotechnica l factors affecting the shoring structure. In General, Pearson correlation or bivariate correlation is a statistic that provides a measurement of the linear correlation between two variables X and Y. It has a value between +1 and -1, where 1 is a total pos itive linear correlation, 0 is no linear correlation, and -1 is a total negative linear correlation [13]. 1. Relative importance index: TABLE VII RANK ED OF GEOTECHNICAL FACTORS No. Factors Frequency RII Rank 1 2 3 4 5 1 Groundwater level 0 0 3 12 5 0.82 2 2 Effect on nearby utilities 1 2 9 6 2 0.66 3 3 Nature of soil 0 0 0 6 12 0.84 1 4 Water from the side of the excavation 0 4 13 2 1 0.60 4 During the geotechnical investigation, the soil is ranked first with a relative importance index (RII) value of 0.84. The main reason is obtaining information about the soil condition used to select the shoring wall's type and depth and angle of inclin ation for the tie -back anchors. The groundwater level is ranked second with an RII value of 0.82. The groun dwater level highly affects excavation depth and challenges the excavation process by incurring additional cost for continuous pumping. This process caus e delay for the whole project life. These two factors extremely affect the geological investigation, an d great care must be taken when preparing a geotechnical analysis. Effect on nearby structure and water which comes from the side must be carefully investigated and ranked with an average RII value of 0.66 and 0.60 third and fourth, respectively. Excavatio n work must not be started until steps are taken to prevent the collapse or partial collapse of any potentially affected building or structure. Any excavation below the level of the footing of any structure, including retaining walls that could affect the structure's stability, must be assessed by a competent technical individual and secured by a suitable grou nd support system designed by an expert . 2. Pearson correlation: TABLE VIII PEARSON CORRELATION OF GEOTECHNICAL FACTORS Inter - Variables Correlation Groundwater Nearby Utilities Soil Nature Water from side Groundwater Pearson correlation 1 0.055 0.342 .523* Sig. (2. tailed) 0.846 0.212 0.018 N. 20 20 20 20 Nearby Utilities Pearson correlation 0.055 1 0.721** 0.049 Sig. (2. tailed) 0.846 0.022 0.838 N. 20 20 20 20 Soil Nature Pearson correlation 0.342 0.721** 1 0.19 Sig. (2. tailed) 0.212 0.022 0.421 N. 20 20 20 20 Water from side Pearson correlation .523* 0.049 0.19 1 Sig. (2. tailed) 0.018 0.838 0.412 N. 20 20 20 20 **. Correlation is significant at the 0.01 level (2 -tailed). *. Correlation is significant at the 0.05 level (2 -tailed). Journal of Xidian University VOLUME 14, ISSUE 10, 2020 ISSN No:1001-2400 http://xadzkjdx.cn/ https://doi.org/10.37896/jxu14.10/074 698 Table VIII s howed how the group of factors interrelates or correlates and affects each other; this result is based on the SPSS Pearson correlation. Correlation analysis is used to measure the association (linear relationship) between two variables, onl y concerned with the relationship's strength. Groundwater has a significant value of 0.018 with water from the side of the excavation. As the groundwater table increases, the challenges from the side of the excavated area also increase. The nature of soil and effect on nearby utility also linearly related to each other with a significant Pearson value of 0.022. If the soil is weak, it leads to a shrink in volume and affects the nearby structure. B.4 Design Related Factors After evaluating site conditions and shoring selection criteria, the designer should determine if shoring is viable for the project based on the feasibility. The design methodology includes steps to determine the reinforcement members to resist bending mome nt and shear stresses. The soil -cement between the re inforcement members is considered the same way as lagging in traditional walls to resist and redistribute the horizontal stresses to the adjacent reinforcement. In this part, all the structural elements o f the shoring wall are considered and analyzed based on the average RII value and Pearson correlation and ranked. TABLE VIX RANK ED OF THE DESIGN FACTORS No. Factors Frequency RII Rank 1 2 3 4 5 1 Diameter of anchor piles 0 0 3 9 8 0.85 2 2 Spacing between consecutive anchor piles 0 0 3 11 6 0.83 3 3 Height of anchor piles 0 0 5 4 11 0.86 1 4 Diameter of rebar mesh 0 2 8 7 3 0.71 4 5 Spacing of rebar mesh 0 2 13 5 0 0.63 6 6 Angle of inclination of tie -back anchorage 0 1 8 11 0 0.70 5 7 Percentage of stressing 0 4 14 2 0 0.58 7 The anchor pile height has been ranked in the first position, with an average RII value of 0.86. This is because the height of anchor piles and depth of excavation is directly related, and if it is not carefully considered, it will cause a serious stru ctural failure. The height of the wall increased with an increase in the displacement of the structure. The diameter of anchor piles considered the second major factor affects the shoring work's design process by the Relative important index of 0.85. An increase in the pile' s diameter increases displacement near the wall's surface in x and y directions. The designer must give great care while designing those piles. Spacing between consecutive piles is ranked in the third position with a random importance index of 0.83. Horizo ntal and vertical spacing of anchors were considered for this study. Decreasing the horizontal spacing can increase the anchor's stiffness per unit width; with high anchor stiffness, the anchor's compressi on will be quite small. The maximum deformation occ urs near the excavation surface. The diameter of shotcrete meshes and angle of inclination of tie -back anchors are ranked in the fourth and fifth with an average relative importance index of 0.71 & 0.70, respectively. These two factors affect shoring work because the meshes must be good enough to resist the soil's lateral load. The angle of inclination of tie back angel must be calculated carefully by consider ing the nearby utilities and excavation depth. The spacing of shotcrete mesh and percentage of stre ss affects the design processes moderately with RII value of 0.63 and 0.58, respectively. This is because a machine does stress, and it has its own gauge to fix the process, and the bar's diameter also more governs the spacing. Figure 4 : Major Design factor 40% 35% 25% 0%10%20%30%40%50% Pile Depth Pile Diameter Pile SpacingPercentage Major Design FactorsJournal of Xidian University VOLUME 14, ISSUE 10, 2020 ISSN No:1001-2400 http://xadzkjdx.cn/ https://doi.org/10.37896/jxu14.10/074 699 1. Pearson Correlation TABLE X PEARSON CORRELATION OF DESIGN FACTORS INTER - VARIABLES CORRELATION Pile Diameter Pile Spacing Pile Depth Mesh Diameter Mesh spacing Tie- back angle stress Pile Diameter Pearson correlation 1 .575** 0.382 0.104 0.094 0.182 0.332 Sig. (2 tailed) 0.008 0.096 0.664 0.694 0.444 0.152 N. 20 20 20 20 20 20 20 Pile Spacing Pearson correlation .575** 1 .554* 0.385 0.073 194 0.043 Sig. (2 tailed) 0.008 0.011 0.094 0.758 0.413 0.858 N. 20 20 20 20 20 20 20 Pile Depth Pearson correlation 0.382 .554* 1 0.323 0.114 0.201 0.176 Sig. (2 tailed) 0.096 0.011 0.165 0.632 0.396 0.457 N. 20 20 20 20 20 20 20 Mesh Diameter Pearson correlation 0.104 0.385 0.323 1 .642** .538** 0.011 Sig. (2 tailed) 0.664 0.094 0.165 0.002 0.014 0.964 N. 20 20 20 20 20 20 20 Mesh Spacing Pearson correlation 0.094 0.073 0.114 .642** 1 0.074 0.049 Sig. (2 tailed) 0.694 0.758 0.632 0.002 0.757 0.839 N. 20 20 20 20 20 20 20 Tie-back angle Pearson correlation 0.182 0.194 0.201 .538** 0.074 1 0.157 Sig. (2. tailed) 0.444 0.413 0.396 0.014 0.757 0.509 N. 20 20 20 20 20 20 20 Percent of stress Pearson correlation 0.332 0.043 0.176 0.011 0.049 0.157 1 Sig. (2. tailed) 0.152 0.858 0.457 0.964 0.839 0.509 N. 20 20 20 20 20 20 20 **. Correlation is significant at the 0.01 level (2 -tailed). *. Correlation is significant at the 0.05 level (2 -tailed). From the above table, the pile diameter and pile spacing, pile depth and pile spacing mesh diameter, and mesh spacing are significantly correlated with a Pearson correlation value of 0.008, 0.011, and 0.002, respectively. B.5 Construction Technique Factors As the design completed, other challenge faces the shoring work, which is construction technique and environmental fact ors. Shoring is a new technology in the Ethiopia construction industry, and only limited firms engaged; it needs a more advanced workforce and equipment to execute the construction work. Table XI and figure 5 illustrate the number of factors that affect th e construction process with RII and Pearson correlation analysis results . TABLE XI RANK ED OF CONSTRUCTION TECHNIQUE FACTORS No. Factors Frequency RII Rank 1 2 3 4 5 1 Site condition and access to the site 0 0 6 13 1 0.75 4 2 Lack of training 0 0 3 6 11 0.88 1 3 Poor communication 0 0 10 9 1 0.71 6 4 Season 0 0 3 9 8 0.85 2 5 Health and safety 0 0 7 13 0 0.73 5 6 Lack of experience 0 0 5 11 4 0.79 3 7 Corrosion 0 8 11 1 0 0.53 7 Journal of Xidian University VOLUME 14, ISSUE 10, 2020 ISSN No:1001-2400 http://xadzkjdx.cn/ https://doi.org/10.37896/jxu14.10/074 700 Lack of training or skilled labor, season, and experience are the major factors that extremely affect the construction process of shoring work with a random importance index of 0.88 & 0.85. This is because shoring is a new technology, and it needs more advanced and huge equipment and skilled operator for drilling an d shotcrete purposes. As a result of this, continuous training and experience sharing is mandatory. The weather condition or season is the most significant factor that affects all excavation and shoring work. So the stockholders must schedule the work in a dry season. Experience is directly related to the training of workforce; most of the construction workers have experience with ordinary construction work like concreting, mason, or carpeting but have not any related experience in shoring work, so they nee d continuous training and experience sharing. Access to the site, health and safety, and poor communication are factors that highly affect the construction process of shor ing work in the CBD area of Addis Ababa ranked fourth, fifth, and six with an average RII value of 0.79, 0.75, and 0.71, respectively. Condition and location of the site are the major factors because the construction process was executed in a confined and cong ested location (i.e., CBD area). It is difficult to access the site to load and u nload materials like excavated materials and also equipment. Excavation in a deep more than 20m deep is the most dangerous activity, so health and safety or assurance to the workers and also equipment must be considered. Communication also affected highly good communication between owner, consultant, and contractor and was mandatory to minimize cost overran, time delay, and dispute. Corrosion is the last factor that slightly affects shoring work with a Relative Importance I ndex of 0.53. This is because all the steel structures are covered with concrete, and even the tie -back rad also has a cover, so; all the components are safe from corrosion. Figure 5: Construction Technique Factors 1. Pearson Correlation TABLE XII PEARSON CORRELATION OF CONSTRUCTION TECHNIQUE FACTORS Inter - Variables Correlation Access to site Training communication Season Health & Safety Experience Corrosion Access to site Pearson correlation 1 0.131 0.435 0.119 0.44* 0.105 0.204 Sig. (2 tailed) 0.581 0.055 0.618 0.052 0.661 0.389 N. 20 20 20 20 20 20 20 Training Pearson correlation 0.131 1 0.119 0.024 0.266 0.063 0.468 Sig. (2 tailed) 0.581 0.616 920 0.257 0.791 0.038 N. 20 20 20 20 20 20 20 communication Pearson correlation 0.435 0.119 1 0.424 0.507 0.437 .571** Sig. (2 tailed) 0.055 0.616 0.062 0.023 0.054 0.009 N. 20 20 20 20 20 20 20 Season Pearson correlation 0.119 0.024 0.424 1 0.027 .564** 0.274 Sig. (2 tailed) 0.618 0.92 0.062 0.911 0.01 0.242 N. 20 20 20 20 20 20 20 Health & Safety Pearson correlation 0.44* 0.266 0.507 0.027 1 0.212 0.101 Sig. (2 tailed) 0.052 0.257 0.023 0.911 0.371 0.673 N. 20 20 20 20 20 20 20 Experience Pearson correlation 0.105 0.603 0.437 .564** 0.212 1 0.438 Sig. (2 tailed) 0.661 0.791 0.054 0.1 0.371 0.054 01020304050 Lack of Training Season Lack of ExperiencePercentageMajor Construction Techinque Factors Journal of Xidian University VOLUME 14, ISSUE 10, 2020 ISSN No:1001-2400 http://xadzkjdx.cn/ https://doi.org/10.37896/jxu14.10/074 701 N. 20 20 20 20 20 20 20 Corrosion Pearson correlation 0.204 0.468 0.571** 0.274 0.101 0.438 1 Sig. (2 tailed) 0.389 0.038 0.009 0.242 0.673 0.054 N. 20 20 20 20 20 20 20 **. Correlation is significant at the 0.01 level (2-tailed). *. Correlation is significant at the 0.05 level (2 -tailed). Table XII displayed the Pearson correlation of construction -related factors access to the site is linearly related to health and safety with a significance value of 0.05. Experience with a significance value of 0.1. This is because as the access to site and space availability decrease, it will increase the workers' percentage of risk and even damage to equipment. B.6 Co st Related Factors From the questionnaire distributed to the stakeholders, 100% of the respondent agrees that shoring work is expensive, with different percentage costs per the project's total cost as illustrated in table XIII below. TABLE XIII COST IN PERCENTAGE FROM THE TOTAL COST OF PROJECT Percentage of Cost Frequency Percentage 3% 2 10% 4% 6 30% 5% 10 50% 10% 2 10% Total 20 100% From the above table , 50% of the respondent agree d that shoring work consume d 5% of the total work budget. The cost of shoring work is directly related to the cost of equipment, availability of equipment, a limited number of firms, and laborato ry material. Table XIV ranked and correlate d several factors based on the RII value of ea ch factor. TABLE XIV RANK ED OF COST FACTORS No. Factors Frequency RII Rank 1 2 3 4 5 1 Cost of equipment’s 0 0 6 11 3 0.77 2 2 Availability of Resources 0 2 11 6 1 0.66 3 3 A limited number of firms 0 0 3 15 2 0.79 1 4 Laboratory materials 0 7 9 4 0 0.57 4 A limited number of competent firms ranked in the first position with a relative importance index value of 0.79. This is beca use Addis Ababa is one of the cities that are registering rapid growth globally. The city construction sector also shows a fast growth in which many residential, commercial, and mixed -use buildings have been built for over a decade. Especially in CBD areas where a high rise building is built, shoring work is mandatory. Besides the regulation, the number of firms specializing in shoring work has the inability to cover the demand that comes from the fast growth of the building construction sector. And their lim ited number creates a non -competent market at work. It adds a great burden on those firms without upgrading the capacity to cover and run the ongoing projects properly. This may direct to an increase in cost and delay at the time of the project. The cost of equipment and resource availability is ranked in the se cond and third with an average Relative Importanc e Index of 0.77 & 0.66. Shoring is a machine intensive work, and equipment used for this technique are too expensive to own and rent. The availability of resources like a skilled workforce to operate and fix those machines is another factor that plays a si gnificant role in the project's economy. The last factor is the laboratory's availability, and the cost ranked fourth and moderately affects the project's cost with a random importance index value of 0.57. This is because only tensile for steel and concret e test was conducted, which is common as other ordinary concrete construction. Journal of Xidian University VOLUME 14, ISSUE 10, 2020 ISSN No:1001-2400 http://xadzkjdx.cn/ https://doi.org/10.37896/jxu14.10/074 702 Figure 6: Major Cost Factors 1. Pearson Correlation TABLE XV RII RANK OF COST FACTORS Inter - Variables Correlation Equipment Cost Resource Availability No. of Firms Laboratory Equipment Cost Pearson correlation 1 0.203 0.131 0.479* Sig. (2 tailed) 0.39 0.583 0.033 N. 20 20 20 20 Resource Availability Pearson correlation 0.203 1 .605** 0.106 Sig. (2 tailed) 0.39 0.005 0.656 N. 20 20 20 20 No. of Firms Pearson correlation 0.131 .605** 1 0.021 Sig. (2 tailed) 0.583 0.005 0.931 N. 20 20 20 20 Laboratory Pearson correlation .479* 0.106 0.021 1 Sig. (2 tailed) 0.033 0.656 0.931 N. 20 20 20 20 **. Correlation is significant at the 0.01 level (2 -tailed). *. Correlation is significant at the 0.05 level (2 -tailed). Table XV showed how the group of cost factors interrelates or correlates and affects each other; this result is based on SPSS Pearson correlation cost of equipment has a si gnificant value of 0.033 with laboratory cost. A limited number of firms engage in shoring work, also linearly related to a resource with a significant Pearson value of 0.005. When we see the number of firms within the market demand, it shows a shortage of firms. The number of specialized professional and construction firms on soil protection (shoring) work is limited and leads to cost overrun and time delay. B.7 Summary of Factors Affecting Shoring Work Based on the above discussions, the researcher prepares a group of factors to determine which group of factors highly affects shoring work construction in the study area and filled by the respondent and measured spastically. There were twenty -two key factors that are grouped under five group factors. T able XVI and fig ure 7 clearly presented the rank of this group of factors. TABLE XVI RANK ED OF GROUP OF FACTORS No. Factors Frequency RII Rank 1 2 3 4 5 1 Geotechnical investigation 0 0 2 7 11 0.89 1 2 Design 0 0 5 15 0 0.75 3 3 Construction Technique 0 1 10 9 0 0.68 5 4 Building type and depth of excavation 0 0 3 8 9 0.86 2 0%10%20%30%40%50% No. of Firm Equipment Cost Avaliabilty of ResourcePercentage Major Cost Factors Journal of Xidian University VOLUME 14, ISSUE 10, 2020 ISSN No:1001-2400 http://xadzkjdx.cn/ https://doi.org/10.37896/jxu14.10/074 703 5 Economy 0 0 8 12 0 0.72 4 6 Environmental and safety factors 0 1 14 5 0 0.64 6 The group of factors ranked first is a geotechnical investigation of the proposed site with a Relative Importance Index (RII) of 0.89. The purpose of a geotechnical investigation is to obtain information used to select the wall's type and depth, estimate earth pressures, locate the groundwater level, estimate settlements, the nature of soil by each layer of excavation, and distance from nearby structures through identifying the possible construction problems. So the good geotechnical investigation is the first critical factor to be considered du ring shoring work. Building type and depth of excavation is the second major factor, with an average RII value of 0.86. The depth of excavation is governing and interrelated with different factors. Some of the factors to be considered when the stakeholder s discuss the depth of excavation is listed below:  Function: the building is supposed to have four basement space levels, which is expected to involve excavation of up to 20m of overburden.  Geological and Geotechnical Conditions: the shear strength and compressibility characteristics of formation immediately below the mandatory excavation and extending to the foundation pressure's depth of influence are important factors determining the structure's stability.  Availability of excavation equipment: the cho ice between deep and shallow excavation depends on equipment availability for drilling piles holes.  Availability of time: the use of cast -in-situ piles implies a longer time for excavation and casting than needed for casting a shallow option.  Economy: Pile d foundation systems are generally costlier than any shallow foundation option. Design and economy are listed as the third and fourth main factors of shoring construction with a relative importance index o f 0.75 & 0.72. These factors considered as a group of factor which moderately affects the construction process. Construction techniques are grouped as a factor that slightly affects the shoring work. Figure 7: Major Cost Factors C. Alternative techniques of Shoring Work This part of the study tried to investigate and ask the respondent about the alternative material used in shoring work to decrease the cost, time, and minimize wastage during shotcrete construction. But most of the respondents (55%) have no idea about Ferro - cement , even the material ty pe. However, in the study , awareness creation should be made about Ferro -cement as an alternative material by discussing the physical and mechanical properties. As illustrated in the first chapter, the third specific object ive of the study is to recommend Ferro -cement construction in place of normal rebar will increase some industry significance. It decreases the cost of shotcrete construction by up to 20%. These discussions were made based on the site visit made during data collection and interview made fo r two sites practicing Ferro -cement in shoring work this technique as an input. C.1 Properties of Ferro -cement Ferro -cement, often regarded as just another form of reinforced concrete, is unique concerning material behavior and structural applications' suitability. Ferro -cement possesses a very significant degree of toughness, ductility, durability, strength, and crack resistance that it is considerably higher than that found in other forms of concrete construction [14]. These properties are obtained in structures with a thickness that is less than 25mm, a dimension that is nearly improbable in other forms of concrete constr uction, 0%5%10%15%20%25%30%35%40% Geotechnical FactorsDepth of ExcavtionDesign Economy Construction Techiniquepercentage Group of Shoring Work Factors Journal of Xidian University VOLUME 14, ISSUE 10, 2020 ISSN No:1001-2400 http://xadzkjdx.cn/ https://doi.org/10.37896/jxu14.10/074 704 and a clear improvement over conventional reinforced concrete. Some of the properties of [14] Ferro -cement were discussed below. a) Tensile Behavior Unlike reinforced concrete, the tensile behavior of Ferro -cement is considerably different due to its spacing that is closer and uniformly than in reinforced concrete, and its smaller diameter results in a larger specific surfac e area. This, in turn, affects cracking behavior (finer and number of cracks) in Ferro -cement. b) Compression Strength The high compressive strength of mortar materials contributes primarily to the compressive strength of the Ferro-cement composite. However, the type of reinforcement may have some influence on the compressive strength. c) Flexural strength An experiment conducted to stud y Ferro -cement's behavior, and strength in flexure found that the ultimate moment will increase with increasing matrix grade (decreasing water -cement ratio) and increasing volume fraction of reinforcement. d) Shear Shear strength depends on mortar, strength of wire mesh, volume fraction & shear span. Fatigue Resistance Fatigue strength plays an essential role in restricting F erro-cement in structures subjected to such a loading as in bridges. The strength of the wire, as tested in air, is the primary factor affecting fatigue of the composite. e) Durability When F erro-cement is exposed to an aggressive environment, its successful performance depends greatly on its durability against the environment than on its strength properties. The external causes may be physical, chemical, or mechanical. They may be due to weather ing, the occurrence of extreme temperatures, abrasion, electrolytic action, and attack by natural and industrial liquids and gases. Generally, Ferro-cement has good durability. f) Water (or Liquid) Retaining Capacity: Another special property to be noted w as water retention when the Ferro-cement application was considered in liquid storage tanks. The significant aspect is the small crack widths so that leakage may be minimal. C.2 Advantage of Ferro -cement Construction Ferro -cement is a labor -intensive material that does not require compressors, pumps, or mechanical mixer used for cement and sand mixing, but may be mixed on the ground with shovels. Handwork is good quality and builds pride through solidarity, and it's also peacefully quiet. a. Ease of P lacement It can be easily placed with minimal or no formwork. Cement slurry, the generally used bonding agent, is very cheap & quite effective. Even though the mortar used has a very less water -cement ratio, it can still be worked onto the inverted beams. b. Workmanship The application of Ferro -cement jacketing does not require skilled labor. Even masons well versed with the art of cement plastering can do this job satisfactorily. Only minimal supervision will suffice the job at hand. c. Cost Ferro -cement uses steel wire meshes that are about 2 to 5 times cheaper by weight than ordinary steel bars. The assemblage of those meshes required medium level or non -skilled labor, which is advantageous in developing countries where labor costs are relatively low. C.3 Ferro -cement for Developing Countries  It may be fabricated into almost any conceivable form to meet the particular requirements of the user.  Ferro -cement's construction's basic raw materials such as sand, cement, and reinforcing mesh are readily ava ilable in most countries.  Except for highly stressed areas or critical structures such as deep -water vessels, adequate Ferro -cement construction does not demand stringent specifications.  The cement should be specified its s tandard quality used in building construction. Special grades are unnecessary.  Specific training is necessary for the laborers; providing a skilled supervisor is on hand.  Cement construction techniques are widely known in developing countries, and indigenous construction workers often show a good plastering aptitude.  Transportation, logistics, and materials‐handling are serious problems in developing countries. And Ferro -cement construction simplifies each one.  Under challenging conditions, wire mesh may be hand -loomed on -site from reel s of straight wire. IV. CONCLUSION Urbanization is a worldwide trend in all countries. The need for deep excavation is a result of such urbanization trends. An overview of different deep excavation support types is given for various loading, sub -soil conditions, adjacent structures, Journal of Xidian University VOLUME 14, ISSUE 10, 2020 ISSN No:1001-2400 http://xadzkjdx.cn/ https://doi.org/10.37896/jxu14.10/074 705 environmental constraints, equipment, and technical expertise availability. In the analysis and discussion part, the study ha s determined several factors that affect shoring work construction in CBD areas of Addis Ababa, Et hiopia. Based on the results, the followi ng major conclusions were drawn : a. Poor geotechnical inves tigation and nature of the soil  Lack of well -trained geotechnical investigators and those who interpret that report.  The varying nature of the soil stratum creates a difficult situation to determine the best -suited design parameter and results in uncertainty during excavation work.  A small number of samples are taken to deduct the soil's whole soil nature around the site. b. Design Error  Giving little consideration for existing structure and utility while deciding the length and inclination of anchor tie-backs.  The designer's inability to suggest an alternative soil protection method, while the current construction trend (anchor technology) becomes impr actical in black cotton (expansive) soil.  Improper spacing between anchor piles & shotcrete fibers which will cause structural failure in the shoring system. c. Poor construction techniques d. A limited number of compet itive firms executing shoring construction  The higher gap between the demand from the fast -growing construction industry and the smallest firms specialized in shoring and other substructure works becomes the major cause in raising the work's cost and delaying the projects' overall progress.  The cur rent trend in soil protection works is highly machine -intensive and requires qualified person nel and professionals to execute the work.  The soil stratum found in CBD areas restricted the firms from seeing alternative cost -effective soil protection methods; rather, they will be stacked with the current expensive soil protection shoring technique. ACKNOWLEDGMENT The authors are grateful to all the respondents that made ample support during the data collection , including our friends, especially to Mr. Mussie T. and Eng. Esayas B., anchor foundation specialists .