Backfill Height Research Articles

Research on the method of identifying vertical earth pressure of hinged prefabricated culvert box culvert on the top slab

In China, several expressways have been designed as prefabricated box culverts with hinge connections, which have different structural features from the prefabricated culverts in other countries. The difference would contribute to the culvert–soil interaction of prefabricated box culverts, which could affect the earth pressure on the culvert. Based on the field test and numerical simulation method, a hinged prefabricated box culvert (HPBC) with a span of 4 m and a rise of 4 m was investigated, which was applied to the Xi-Yu expressway in China. The objective of this research was to investigate the vertical earth pressure on the top slab of the HPBC culvert at different backfill heights through the field tests. The FLAC3D software was employed to conduct further analysis of the effects of backfill height, backfill modulus, and foundation modulus on the vertical earth pressure on the top slab of HPBC. The differences between the HPBC and monolithic box culvert (MBC) were also examined. Furthermore, a revised method for calculating the vertical earth pressure on the top slab was put proposed and compared with the AASHTO method for calculating earth pressure on the top of culverts and the values taken from the Chinese culvert design code. The proposed method is capable of improving the accuracy of the earth pressure approach, making it more representative of actual conditions. Subsequently, the sensitivity analysis of backfill height, backfill modulus and foundation modulus to the vertical earth pressure concentration coefficient of the top slab was carried out by using the principle of orthogonal array analysis and the modified calculation method proposed in this paper. The findings of this study offer valuable insights into the determination of culvert top earth pressure of HPBC.

A Study on the Factors Influencing High Backfill Slope Reinforced with Anti-Slide Piles under Static Load Based on Numerical Simulation

Based on a real engineering case, this study employs the MIDAS finite element software to model the reinforced high embankment slope using anti-sliding piles. The accuracy of the finite element method is verified by comparing calculated outcomes with field monitoring data. Expanding on this foundation, an analysis of factors influencing the reinforced high embankment slope is undertaken to scrutinize the impact of diverse elements on the slope and ascertain the optimal reinforcement strategy. The results reveal the following: The principal displacement observed in the high embankment slope is a vertical settlement, which escalates with the backfill height. Notably, the highest settlement does not manifest at the summit of the initial slope; instead, it emerges close to the summits of the subsequent two slopes. However, the maximum horizontal displacement at the slope’s zenith diminishes as the fill height increases—a trend that aligns with both field observations and finite element computations. The examination of the influence of anti-sliding pile reinforcement on the high embankment slope unveils that factors like the length, diameter, spacing, and positioning of the anti-sliding piles exert minor impacts on vertical settlement, while variations in the parameters of the anti-sliding piles significantly affect the slope’s horizontal displacement. When using anti-sliding piles to reinforce multi-level high embankment slopes, factoring in the extent of horizontal displacement variation and potential cost savings, the optimal parameters for the anti-sliding piles are a length of 15 m, a diameter of 1.5 m, and a spacing of 2.5 m, presenting the most effective combination to ensure superior slope stability and support.

Subsoil stiffness effects on the bridge-abutment dynamic behaviour

Integral abutment bridges (IABs) are robust structures that avoid the use of bearings and expansion joints and are relatively maintenance-free compared to conventional bridges. The seismic design code of IABs is not fully developed, and the complex soil-abutment interaction is not well understood. Therefore, research was carried out at the Schofield centre, the University of Cambridge, to understand the backfill-abutment interaction under earthquake loading, aimed at developing design guidelines for the industry. Understanding the mechanics by which the foundation soil stiffness and strength govern the abutment deformation and, thus, the earth pressures generated behind the abutment is essential. Two centrifuge tests have been conducted simulating an abutment with the conventional abutment-deck connection (or semi-integral abutment bridge), where moment restraint is released. In this paper, the dynamic response of the abutment founded on dry and liquefiable sandy soil is compared. Different deformation modes have been observed depending on the relative abutmentsoil stiffness. The abutment experienced minimal base displacement in dry sands. Conversely, the abutment witnessed cyclic rotational ratcheting about the deck level in liquefiable soil. The dry soil test helped identify the zones where soil stiffness and strength loss can be critical. In the case of the saturated test, the water table level was up to one-third of the abutment height, fully saturating the foundation soil while the backfill height was dry. The comparative results highlight the vulnerability of semi-integral abutment walls to liquefaction-induced failure, as witnessed in the 2011 Christchurch earthquakes.

Soil–Structure Interaction Analysis Using the Finite Element Method in Thin-Walled Steel Pipes Buried under Haul Roads

This paper addresses the challenges associated with steel pipes used for transporting liquid fluids within buried sections of mining facilities, specifically in areas with heavy mining vehicles. While existing design standards, such as AW-WA M11, and manufacturer recommendations largely consider loads from vehicles like the AASHTO HS20 or Cooper E-80, both weighing below 35 tons, these guidelines inadequately represent the actual loads experienced on certain mining roads, notably those accommodating heavy vehicles, like haul roads. The research presented here focuses on the interaction between soil and buried steel pipes under the substantial loads exerted by mining vehicles with a maximum gross load of up to 612 tons, inclusive of hauled material weight. Utilizing a parametric study with the finite element method, the paper identifies critical variables influencing efforts and deflections calculations in these facilities. The analysis of 108 models, varying parameters related to trench pipe installation conditions, offers insights that empower designers to refine soil trench parameters in mining facilities, mitigating pipe failures and optimizing installation costs. Ultimately, the key influential variables affecting pipe deflection and stress are identified as the trench backfill height and the elasticity modulus of the trench lateral fill.

Experimental Study and Numerical Simulation of the Effect of Rigid Pile Composite Foundations on Slab Culverts

For culverts installed in soft soil, the rigid composite pile foundation is used for soil treatment, and the stresses around the culverts are complicated. Centrifuge experiments and numerical simulations are conducted to investigate the vertical earth pressures and soil settlement over a slab culvert under high backfill in soft soil, and the foundations are treated with rigid composite piles. The influences of lateral pile length and pile spacing on the earth pressures at the top of the culvert are analysed, and they have significant effects on the vertical earth pressure coefficients. It also indicates a strong correlation between the backfill height and the vertical earth pressure coefficients. For a high-backfill culvert, there is a uniform settlement surface where the settlement of the interior and exterior soil prisms is at the same level. According to the experiments, the height of the uniform settlement surface and the vertical earth pressures decrease with increasing the lateral pile length and pile spacing. Numerical simulations were conducted using finite element software Midas GTS to evaluate the performance of the experiments. Further, recommendations for selecting an appropriate pile composite foundation for slab culvert in soft soil are provided.

Monitoring of barricade pressure during the entire backfilling process for a high iron mine stope

The stability of the backfill barricade is an important foundation for safe mining production. The backfill material is transported to the underground mined-out area. During the backfilling process, it is difficult to directly monitor the curing process of backfill body and its lateral load on barricades. This severely affects the accurate formulation of the mining and backfilling strategy as well as effective control of associated costs. In order to investigate the change law of pressure on barricade, a continuous monitoring experiment was conducted by installing pressure sensors inside the barricade. The results indicated that the pressure on barricade showed an initial increase followed by a subsequent decrease and eventual convergence towards zero with the increase in backfill height and curing time. A barricade pressure prediction model was established for discontinuous backfilling conditions using a fitting method that characterizes the relationship between backfill height and barricade pressure through a Gaussian function. Finally, from both on-site monitoring and theoretical analysis, it was jointly demonstrated that the continuous filling of Luohe iron ore mine quarry has safety and feasibility.

Assessing the stresses and magnitude of plastic hinge in a tunnel conduit made of precast metal corrugated structures taking into account the soil backfill parameters

The object of research is a tunnel conduit made of star-shaped metal corrugated structures. The stresses and magnitude of the plastic hinge occurring in the metal corrugated structures of the tunnel conduit were investigated, taking into account the degree of compaction and the height of the soil backfill. It was established that when the height of the backfill above the tunnel conduit made of precast metal corrugated structures increases and the degree of compaction of the soil backfill decreases, there is an increase in the values of stresses and plastic hinge in metal structures. With the height of the backfill above the conduit equal to 2.75 m and the degree of compaction of the soil backfill RP=80 %, stresses of 235.89 MPa are reached, exceeding the permissible 235 MPa. At the same time, the value of the plastic hinge is 1.03, which exceeds the normative 1.0. It was established that at embankment heights above the tunnel conduit structures from 1.75 m to 2.0 m, the smallest difference in stresses and magnitude of the plastic hinge is observed. At RP=98 %, the stress difference is 0.66 MPa, and the value of the plastic hinge is 0.008. In the case of the height of the embankment above the conduit from 1.5 m to 1.75 m, the stress increase was 5.5 MPa, and the value of the plastic hinge – 0.031. When the embankment height increases from 2.0 m to 2.25 m, the stress difference is 7.57 MPa, and the value of the plastic hinge is 0.041. It was determined that when the height of the embankment above the conduit was increased by 1.0 m in the range from 0.75 m to 1.75 m, the stress difference at RP=98 % increased by 27.84 MPa. However, when the height was increased by 1.0 m in the range from 2.75 m to 3.75 m, the stress difference increased by 12.66 MPa. At the same time, the value of the plastic hinge at embankment heights from 0.75 m to 1.75 m increased by 0.139, and at embankment heights from 2.75 m to 3.75 m – by 0.093

Study on the Influence of Wet Backfilling in Open Pit on Slope Stability

The residual open pit left in the wake of open-pit mining poses significant safety hazards, with backfilling being an effective strategy to wholly eliminate these risks. The stability of the slope following wet backfilling, however, should not be overlooked. This paper examines the impact of the seepage field conditions and backfill height on the stability of open-pit slopes using a case study of cemented backfill in a specific open pit in Anhui Province. Moreover, it utilizes onsite research, Slide simulations, and similar simulation tests. The study findings suggest that as the height of the tailing solidification backfill increases, the safety factor of open-pit slopes gradually elevates. When the backfill height exceeds 10 m, all profiles of the studied open-air slope fulfill the stability prerequisites. Furthermore, when the solidification backfill reaches 20 m, all profiles of the studied open-pit slope satisfy the stability requirements. The research outcomes offer a methodology for mining corporations to avert slope instability and destruction, thereby providing effective safeguards for the extraction of scarce resources in mines.

Ultimate capacity of large-span soil-steel structures

The ultimate limit states provided by current design codes and standards were based on full-scale field and laboratory tests performed on soil-steel structures (SSS) of spans less than 10.0 m. Recently, the spans of SSS have increased up to 32.4 m with the tendency to exceed this record. The ultimate capacity of SSS utilizing the deepest corrugation profile, i.e., 237 mm depth and 500 mm pitch, has not been yet investigated under earth and truck loading. The current study evaluates the ultimate capacity of the world’s largest-span SSS with 32.4 m span and 9.57 m rise, using three-dimensional (3D) nonlinear finite element simulation. The investigation covered both the maximum backfill height and ultimate truck loading conditions. The 3D finite element modelling technique under ultimate loading was validated by full-scale test measurements of 10.0 m span soil-steel structure subjected to tandem axle loading. The critical straining actions obtained from the steel structure at ultimate condition was used to evaluate the ultimate limit states provided by the Canadian Highway Bridge Design Code (CHBDC, 2019) and AASHTO (AASHTO LRFD, 2019). The results revealed that the ultimate capacity of the SSS was reached without conforming to all ultimate bounds provided by the current design codes. Finally, a limit state function was proposed to account for the structure instability that may occur to the steel structure under ultimate loading condition. The proposed function successfully predicted failure in the steel structure under all cases considered in the current analysis before failure occurred in the numerical results.

Influence of Using Tire-Derived Aggregate on the Structural Performance of Buried Concrete Pipe under Embankment Load

Induced trench method is a well-known technique usually used to reduce the soil pressure applied on buried pipes. This method involves the use of a lightweight compressible material above the buried pipe to increase the positive arching, and thus, to decrease the soil pressure applied on the buried pipe. However, little efforts have been given by previous studies to check the applicability of using tire-derived aggregate (TDA) as the light weight and compressible material in the induced trench method, where it is not clear if the TDA could be used to increase the positive arching for the case of concrete pipes with different diameters and backfill heights. Thus, this paper investigates the effect of using TDA on the structural performance of buried concrete pipes subjected to soil load using a validated three-dimensional finite element model. A sensitivity analysis has been carried out to examine the effect of the configuration of the TDA, backfill height, and pipe diameter on the performance of the TDA in reducing the pipe wall bending moment. It was found that increasing the backfill height decreases the performance of the TDA. Furthermore, increasing the pipe diameter up to 1.2 m increases the TDA performance. However, the performance of the TDA significantly reduces as the diameter increases from 1.2 m to 2.4 m. In addition, it was also observed that the TDA configuration has a remarkable influence on its performance, where it is necessary to place the TDA layer on top of the pipe crown to increase the positive arching. The results reported in this paper provide useful addition to the literature and will help designers to ensure the economic design of buried pipes using recyclable materials.

Performance of Bridge Envelope During Earthquake Using Finite Element and Artificial Neural Network Techniques

Background: Bridges are one of the most critical parts of a transportation network that may be damaged during earthquakes and it is necessary to have a prediction model for bridge responses under seismic loads that can be extended to other situations. Soil stiffness significantly affects load distribution when soil, piles, abutment, and superstructure all act as a combined system to resist lateral loading on a bridge. Methods: A two-dimensional (2D) model of integral abutment bridge (IAB) with soil springs around piles and behind the abutments for 18.3m, 35.4m, and 64.5m spans respectively, was developed with finite element (FE). The input variables were bridge span, backfill height, soil stiffness behind abutment, and soil stiffness around piles. Also, Artificial Neural Network (ANN) was examined for pile lateral force, pile displacement, pile head moment, girder axial force, and abutment moment. Results: Using FE the prediction of critical response for medium span (i.e., 123.6m) and large span (i.e., 249m) by ANN was performed. Findings show that backfill stiffness has an important effect on lateral displacement. The best performance was related to high stiffness backfill with intermediate clay around the pile. Conclusion: Stiffness of clay around the pile has an important effect on lateral displacement, pile lateral force, pile bending moment, girder axial force, and girder bending moment at the abutment.

Monitoring of in-situ properties for cemented tailings backfill that under drainage condition

Cemented tailings backfill technology is commonly applied to fill mined-out areas generated by mining activities. Understanding the evolution of physical and mechanical properties of tailings backfill is important for the design of a safe and high-efficient backfill system. The in-situ performance monitoring experiments in the real stope and the in-situ similarity simulation monitoring experiments (under the drainage and undrainage conditions) are conducted. The evolution mechanisms of in-situ properties such as bleeding rate, sedimentation rate, temperature, pore water pressure, total stresses, and effective stress during the curing of tailings backfill are analyzed. The results indicate that the sedimentation rates for the tailings backfill under drainage and undrainage conditions are 6.07% and 3.99%. The average maximum temperatures are 37.5 and 33.9 °C. The setting times under the two conditions are 7.1 and 355.2 h. Comparatively, the setting time measured in the stope where one filter pipe is installed is 22.6 h, indicating that the drainage condition significantly affects the sedimentation, temperature, and setting in the field tailings backfill. As the height of the tailings backfill increases, the deviation between the theoretical value and measured data for the total stresses in the field tailing backfill gradually enlarges. This phenomenon suggests that the arching of pressure formed at lower tailings backfill could reduce the load, and contribute to the stability of stopes. In addition, the effects of filling speed and backfill height on the evolution of the total stresses are discussed.

Structural Analysis and Design of Sustainable Cross-Laminated Timber Foundation Walls

There is widespread enthusiasm toward utilizing mass timber panels (MTP), mainly cross-laminated timber (CLT), in construction, including for the basements of low-rise buildings. CLT is deemed a sustainable alternative to the widely used concrete foundation walls due to significant advantages such as less vulnerability to cracking due to uneven load distribution and presence of concentrated loads, higher thermal resistance, less construction time due to whole-wall prefabrication and installation, and less detrimental environmental effects. This study is part of an extensive research program aimed at developing the structural analysis and design concepts and methodology for constructing house foundation walls using MTPs, focusing on the usage of CLT. After comparison of CLT basements with their equivalent concrete ones from the sustainability point of view, and a brief discussion on geotechnical and hygrothermal considerations, the main theme of the article includes the structural analysis and design methodology, requirements, and the procedure to achieve a reliable and efficient design of a CLT basement. A simplified analysis procedure to design the laminate thicknesses and the number of layers in CLT foundation walls for different scenarios considering various variables such as soil type and backfill height is discussed, and results in the form of pre-engineered design tables are provided. The findings of this study demonstrate that, depending on the soil type and backfill height, 3–7-ply CLT panels would be needed for net wall heights of up to 3 m. Additionally, advanced finite element analyses are performed on sample architypes to validate the simplified analysis procedure used for design. It is shown that the proposed analysis procedure and the pre-engineered tables produce conservative and efficient results.

Effect of large-span three-sided culvert configuration on its performance at service and ultimate loading conditions

The configuration of large-span reinforced concrete (RC) three-sided culverts (TSCs) with flat top slab can affect their geo-structural performance. Therefore, the measured responses of an instrumented 13.5-m-span TSC under 3.0 m of backfill were analyzed to elucidate the effect of its configuration on the pressure distribution along the top slab and sidewalls as well as underneath the footing. The field monitoring data were utilized to validate two-dimensional (2D) nonlinear finite element models (FEMs) that were then employed to analyze the culvert response at service loading conditions. The validated nonlinear 2D FEM was then extended to analyze the ultimate limit state (ULS) response at deeper backfill heights. In addition, the influence of the culvert sidewall and footing pedestal heights on the footing-culvert system performance was investigated. To further examine the effect of sidewall height on the structural capacity of the precast culvert unit, 3D nonlinear FEMs were developed to simulate a laboratory load testing for the precast unit of the subject TSC with different sidewall heights. The results from the 2D FEMs demonstrated non-uniform vertical earth pressure distribution on the top slab at all backfill heights. The height of the culvert sidewall was found to influence the location of failure surface and the maximum backfill height at failure. Moreover, the results clearly demonstrated significant influence of sidewall configuration on the performance of the footing-culvert system. Relatively short sidewall with long footing pedestal performs better than long sidewalls with short pedestals. The 3D FEMs showed that the precast unit structural capacity could decrease by up to 18% due to increased sidewall height.

Performance of the bamboo geotextile system ‘GEOBAMTILE’ for road construction on deep soft ground

Infrastructural development faces the dilemma of attempting to construct over deep soft ground. Practical methods to support heavy engineering construction over soft ground has evolved tremendously. Proper ways to treat a depth of softness that extends to a great depth technique are pretty expensive and non-functional. Furthermore, those available methods have their practical limitation during implementation. Bamboo Geotextile System “GEOBAMTILE” is designed to solve a critical contemporary civil engineering problem of supporting hefty construction safely over deep soft subgrade without attracting excessive settlements in due course. This study aims to evaluate the performance of Geobamtile on settlement reduction. Methodology to achieve the objective of the study is by data collection from the site. The next phase continues with construction of road work and analysing the result collected. Based on this study, it is found out that the implementation of Geobamtile reducing the settlement rate of foundation effectively. Compared to the predicted settlement design, the field data result is 88mm to 100mm compare the predicted settlement for the first 100 days is 301mm to 341mm. Soil settlement reaches a relatively constant value despite an increase in backfill height. From this study it shows that Bamboo Geotextile System “Geobamtile” is effective for heavy construction over deep soft ground compare to the predicted settlement design.

Design guidelines for reinforced concrete three-sided culverts

A comprehensive parametric study is conducted to investigate the structural performance of reinforced concrete (RC) three-sided culverts (TSCs) and the applied earth pressures. Nonlinear finite element models were established for a range of TSCs configurations and were validated using full-scale field measurements of three TSCs with spans of 7.3, 10.4, and 13.5 m. The parametric study covered a wide range of main design factors, including backfill height, installation method, backfill soil type and compaction level, and concrete compressive strength. The results demonstrated that embankment installation method resulted in slightly higher earth loads on the culvert top slab and sidewalls compared to trench installation method. The results revealed that vertical arching factors (VAFs) stipulated in the CHBDC (CSA, 2019) for B1 and B2 standard installations consistently overestimated the vertical earth pressure on the top slab. Therefore, the equation proposed by AASHTO (AASHTO LRFD, 2014) for evaluating VAFs was modified and proposed to evaluate vertical earth pressures for TSCs. It was found that culvert installation involving dumped soil or moderately compacted sidefill along with compacted backfill on the top slab significantly increased the vertical earth loads on the top slab, and adversely affected the structural performance of TSCs and their ultimate capacity. Therefore, these compaction scenarios should not be used in the construction of TSCs. The results also demonstrated that the predicted maximum backfill height at failure could increase by up to 50% when concrete with higher compressive strength (i.e., 60 MPa instead of 40 MPa) is used in manufacturing the RC TSCs. Finally, midspan vertical deflection limits are proposed to ensure that the crack width of the RC culvert satisfies the allowable limits considering soil-structure interaction effects.

Class-A prediction of three-sided reinforced concrete culverts and numerical investigation of the supporting strip footing geometry effect

This paper presents three-dimensional finite element analyses conducted to optimise the instrumentation plan for monitoring the structural performance of reinforced concrete three-sided culverts (TSCs). Numerical models were developed for three TSCs with spans of 7.3, 10.4, and 13.5 m to establish the anticipated range of measurements. The TSCs were instrumented with 30 pressure cells and 56 strain gauges. Comparing the numerical predictions with field measurements of the 10.4-m-span TSC verified the adequacy of simulating the concrete behaviour as linear elastic for estimating the applied earth pressures. However, such simplification would lead to underestimating the induced strains in the culvert body in case cracks develop. In addition, Class-A predictions of soil pressures on the culvert were compared with the field measurements of a 7.3-m-span TSC. The calculated soil pressures agreed well with the field measurements. The measured and calculated earth pressures suggest a vertical arching factor of 1.05 at the final backfill height. The influence of the shallow foundation geometry was investigated employing the validated numerical model. It was found that the footing geometry has no influence on the applied earth pressures. However, the calculated stresses below the footing edge on the backfill side decreased as the footing flexibility increased.

Numerical and experimental analyses for rubber-sand particle mixtures applied in high-filled cut-and-cover tunnels

With the rapid development of the automobile industry and transportation, the disposal of scrap tires has become an internationally recognized economic and environmental problem. Fortunately, high-filled cut-and-cover tunnels (first construction and then layered backfill) provide ideal solutions for waste treatment and resource reuse as mixtures of scrap tire rubber particles and sand are used as lightweight fill material (LFM) in high-fill cut-and-cover tunnels (HFCCT). Because the backfill above the cut-and-cover tunnel (CCT) requires a large quantity of material, an appropriate ratio of scrap tire rubber particles and sand should be selected as the LFM mixture. If LFM of different thicknesses is buried above the CCT, it will inevitably bring varying degrees of influence on the earth pressure around the CCT, leading to structural deformation and soil settlement above the CCT. In this paper, a method of combining numerical simulation and model test is presented to help analyze the macroscopic and micromechanical properties of LFM through the stress–strain change and the contact force chain distribution. In the model test, certain factors influencing the earth pressure, the structural deformation, and the soil settlement mentioned above are considered, including the fill height and the embedding depth of the LFM. The results show that when the rubber fraction by volume (RF) is between 30% and 45%, the deformation and load-bearing capacity of the LFM are the most stable. Moreover, a suitable rubber fraction by volume (RF = 40%) and backfill height (between 0.63 ∼ 0.83 times the height of the CCT) can eliminate the stress concentration at the top center of the CCT.

Safety Analysis of Synergetic Operation of Backfilling the Open Pit Using Tailings and Excavating the Ore Deposit Underground

The transition from open pit mining to underground mining is essential for mineral resources to achieve deep excavation. Recently, cemented paste backfill (CPB) has been proposed as a novel technology to achieve open pit backfill (OPB). The proposed method not only eliminates the danger of the open-pit slope but also reduces the disposal of waste tailings. In order to ensure safe mining during the synergetic operation of OPB and underground mining, it is of great significance to improve this technology. In the present study, an open-pit metal mine in Anhui Province was taken as the research object. Then, the safety of underground stope roofs, underground backfill pillars, and open-pit slopes was evaluated during OPB. To this end, numerical simulations were performed and experiments were conducted on a similar physical model. Accordingly, the backfill mechanical parameters were optimized. The obtained results show that backfill height exerts the most significant effect on the safety of roofs and underground backfill pillars, accompanied by small displacements along the vertical direction during the backfill process. Moreover, concentration was observed at the foot of the slope, while the overall structure remained stable with no considerable displacement. The overall safety factors met the safety requirements. Based on the obtained results, the optimal foundation strength, foundation height, backfill strength and backfill height were 4 MPa, 10 m, 1.5 MPa, and 120 m, respectively. Moreover, it was concluded that displacements in the abovementioned three regions tend to be stable when the backfill height exceeds 150 m without damage. The present article provides a certain theoretical and application guideline for OPB practices in similar metal mines and suggests possibilities for cleaner production.

Cost Optimization of Cantilever Retaining Wall Using Flower Pollination Algorithm

The flower pollination algorithm is nature-inspired in which it mimics the pollination process of the flowers. In this study, the cost of the cantilever retaining wall is optimized, which includes the cost of concrete and the cost of reinforcement steel. The eight design variables define the geometry of the RC wall. The external stability and structural stability are considered as constraints. Overturning, sliding, eccentricity, and bearing are considered external constraints. The structural stability constraints are shear and moment failure of toe slab, heel slab, and stem. The fitness function is developed using a static exterior penalty. The study found that the FPA outperforms the non-dominated sorting genetic algorithm (NSGA-Ⅱ) in this design problem without violating any constraints. An analysis of sensitivity is carried out for the angle of internal friction of backfill soil and the angle of backfill slope. Results show that the total cost rapidly increases after 5 m height of backfill but significantly decreases with the internal friction angle of backfill increases. For backfill heights from 6 to 10 m, the change in cost is significant after the value of the inclination angle of 15°.