Pit Design Research Articles

Soil parameters inversion and influence based on MIDAS GTS

The foundation pit engineering design is continuously optimized and improved. With the development of scientific computing, especially the finite element analysis software technology in the popularization of soil parameter inversion, it provides a new technical approach. Midas GTS was developed to quickly complete the analysis and design of geotechnical and tunnel structures. It provides a variety of theoretical analysis and design functions, as well as a variety of constitutive and user-defined constitutive models to properly analyze the safety of foundation pit design. has become an important method for obtaining effective parameters in recent years.

Back-Analysis of the Bingham Canyon South Wall: A Quasi-static Complex Slope Movement Mechanism

A 610-m-high portion of the South Wall of the Bingham Canyon open pit has experienced slow-moving slope deformations several times during spring melt until the movement was stabilized approximately 7 years ago. To develop and optimize life of mine slope designs, an understanding of the mechanism(s) and associated material strength parameters, was required. A back-analysis and calibration of the strength parameters for the salient rock mass and structural features was undertaken. The back-analysis consisted of understanding the conditions and trigger for the slope movement and adjusting strength parameters to match available monitoring data (time-domain reflectometer cables, inclinometers, interferometric radar data, etc.). The trigger for the movement was attributed to the spring high-perched water levels in the upper part of the wall. A FLAC3D model was built to back-analyze and capture the complex behavior of the slope during the high deformation period (August 2011). The back-analysis was consistent with the conceptual model and indicated that the slide was composed of mixed mechanisms, namely, a structurally controlled mechanism for the upper wall and a rock mass controlled mechanism for the lower wall (toe). The analysis supported by a converging FLAC3D model, were used to guide mining engineers in developing robust pit design in the South Wall. Today, the O-Slide instability is being fully managed by rigorous monitoring, implementation of a toe buttress, successful dewatering efforts, and unloading of the movement mass as another slice of mining advances down the South Wall.

Probabilistic assessment of potential leachate leakage from livestock mortality burial pits: A supervised classification approach using a Gaussian mixture model (GMM) fitted to a groundwater quality monitoring dataset

After a severe epidemic of foot-and-mouth disease (FMD) in 2010–2011 in South Korea, more than 3 million livestock carcasses were promptly disposed of in a large number of on-site livestock mortality burial pits (approximately 44,000 sites) over the country. There has been significant concern regarding the potential leakage of carcass leachate from burial pits into underlying groundwater. To detect leakage, we monitored three chemical parameters (NH4+-N, Cl−, and EC) of groundwater from monitoring wells downgradient of burial pits (n=274) in 2011. The monitored data were applied as the prediction set to a supervised classification scheme using the Gaussian mixture model (GMM) which involves chemical analysis of both the leachate effluent and background groundwater (as the training set). The GMM was tested to the different data distributions of the training set and resulted in statistically accurate models (with 10-fold CV error <16%) that allocate the probabilistic leachate leakage (i.e., the posterior probability) to each burial pit in the prediction set. However, the overall likelihoods tended to be underestimated due to the uncertainty mainly associated with leachate contamination in background groundwater. Therefore, the best-fit GMM for the bivariate distribution of NH4+-N and Cl− was tuned by redefining the probability density function (pdf) of background groundwater only using a Gaussian component fitted to the distribution at the lowest concentration levels, which predicted the leakage more precisely. Consequently, according to the cutoff (p=0.5) of the probability, we concluded that leachate leakage occurred in 49% (n=133) of the burial pits. This study suggests that the burial method for the disposal of livestock carcasses requires careful consideration on the site selection and pit design to prevent leakage, and also demonstrates that GMM is very flexible for the model tuning in the supervised classification scheme.

Ultimate pit limit determination for semi mobile in-pit crushing and conveying system: a case study

ABSTRACT Semi mobile in-pit crushing and conveying systems have different pit shape requirements to traditional truck haulage systems due to the inclusion of a conveyor flight in the pit. As the shape of a pit is heavily influenced by the ultimate pit limit, it is desirable to have the additional shape requirements included in the ultimate pit limit determination process. This paper introduces in-pit crushing and conveying systems and discusses their differences and benefits. The differences and requirements of pit design between truck haulage and semi mobile in-pit crushing and conveying systems are then highlighted. A method of including the additional requirements during the ultimate pit limit determination is presented. A case study has been included that shows the method working successfully, with scheduling of the pits to further highlight semi mobile in-pit crushing and conveying viability. This case study shows that through the reduced mining costs, a semi mobile in-pit crushing and conveying pit can return a higher Net Present Value, despite being smaller than the traditional truck and shovel pit for the same deposit. The development of this method provides the opportunity for the metalliferous industry to accurately determine ultimate pit limits for a mines considering the use of semi mobile in-pit crushing and conveying systems.

3D Fabric analysis of Venetia Mine, South Africa: Using structural measurements and implicitly-modelled surfaces for improved pit slope design and risk management

The geometry and structural history of high-grade granite-gneiss units, which host the Venetia diatremes in South Africa, have been modelled in 3D using an implicit, rules-based, conditional geometrical technique. The volume contains a pervasive, dominant foliation, which forms the main plane of strength anisotropy in ongoing design and mining of the Venetia pit, which has a planned final depth of approximately 465 m below surface. The well-developed S2 foliation is a continuous feature that was locally re-oriented during D3 and D4 and localised ‘wrapping’ around competent amphibolite/hornblendite lenses or boudins. These local variations have important implications for pit design and operational risk management, particularly where they dip adversely out of the slope, or occur at the base of bench stacks, or in inter-ramp areas. These structures, when undercut by dips steeper than their friction angle, may result in planar sliding, presenting an operational safety risk. Best practice requires early identification of these occurrences, to make design adjustments where warranted. Lithological contacts, which have been transposed into parallelism with the S2 foliation, and a robust set of structural data collected over the last 10 years, are analysed to quantify and represent the variable orientation of S2 in 3D space. This contribution describes several methods, using leading software packages such as Leapfrog Geo™, Micromine™ and Python, to generate representative S2 form surfaces and anisotropy block models, both of which are used for downstream geotechnical engineering analysis. Outputs are also translated into apparent dip “heat” maps that show the angular interaction between S2 foliation and a pit design surface. These methods augment, and lessen the dependence on, typical 2D wedge-shaped design sectors that are commonly employed in pit design. This approach has important safety and economic benefits. As the rock mass fabric is characterised, it supports quick identification of potentially higher-risk areas (e.g. adverse undercut fabric with greater likelihood of slope instability) in current mine plans, which justifies more detailed analysis and/or additional monitoring controls to ensure safe and efficient mining. It also allows rapid mine design optimisation.

Determination of safety factor value of PIT design based on cohesion and friction angle

This research was conducted in East Kalimantan area. Which aims to determine the value of safety factor to know the level of the slope stability in order to make the right PIT design. The greater the SF value of a slope, the more stable the slope, so the activity of production will remain safe. This analysis uses bhisop method. This method is used by assuming the type of landslide that will occur on the high wall side is a circular landslide, while on the low wall is the plannar landslide. In this analysis, the data used are slope geometry, cohesion values and friction angle resulting from direct shear and unit weight from basic test. The greater the value of cohesion and the friction angle, the value of the safety factor will also be greater, then the PIT design will be stable. Result of this research, the SF values are varied, on the high wall side of 2,050 to 8,298, on the low wall of 2,174 to 12,670 and on the end wall of 1.838.

Study on Space Effect Coefficient of Deep Foundation Pit

The foundation pit is a three-dimensional space system with length, width and height. The current code is designed according to the plane problem. It does not consider the space effect of foundation pit. Based on the numerical model, the effects of the ratio of depth to length and the ratio of the distance of pit angle to the length of pit on the spatial effect was studied. It provides the basis for optimal design of deep foundation pit. The results are as follows, when the ratio of depth to length of foundation pit is less than 1/8, the deformation in the middle of foundation pit is close to that in plane strain design. The influence coefficient of foundation pit space changes exponentially with the ratio of the distance of pit angle to the length of pit edge. The influence coefficient of foundation pit space changes exponentially with the ratio of foundation excavation depth to pit length.

Observed Performance of a Large-Scale Deep Triangular Excavation in Shanghai Soft Clays

An 18.4-m-deep triangular foundation pit with in-plane excavation area of approximately 10,000 m2 was constructed in soft clay. The excavation located at Hongqiao comprehensive transportation hub center in Shanghai, in which an energy gallery, many underground pipelines, and viaduct piers exist. Deformation characteristics of the foundation pit and the impact on the adjacent buildings and structures were observed by a monitoring system during excavation. Field data including wall deflections, vertical wall movements, ground subsidence, as well as vertical column movements were analyzed and compared with other excavations of metro stations or rectangular excavations in Shanghai. This excavation exhibited different deformation characteristics from other excavations because of its triangular shape with acute corners. The deformation law of this special excavation was beneficial for the design and construction of special-shaped foundation pit in complex environment.

A methodology for automatic ramp design in open pit mines

The design of ramps in open pit mining is a complex problem that, even though it has a great impact in the value of a project, does not rely on optimization tools as other problems like the computation of nested pits or direct block scheduling.In this paper, we present a methodology for the design of open pit ramps that aims to assist the design of open pit phases. The methodology is based on mathematical programming and suggest the location and design of a ramp for a reference pushback given as input, then considers constraints like interramp angles, decline and with of the ramp and generates and generates a new puchback with the highest possible value and on a second stage it applies an interpolation algorithm to produce an actual profile of the phase. This work focuses on this second, algorithmic part to show that the interpolation algorithm can generate profiles that are very close to the optimal ones, generated by the mathematical model, and therefore together they provide a viable procedure for automatic pit design in open pit mines.

Kajian Geoteknik Untuk Desain Pit Tambang Batugamping Di Daerah Karang Dawa, Kecamatan Margasari, Kabupaten Tegal, Jawa Tengah

Location of research situated in the village Karangdawa, district Margasari, Tegal Regency,&#x0D; Central Java. The location of the research is the exploration Licences PT.&#x0D; Indocement Tunggal Prakarsa Tbk., with commodities limestone. This research is aimed at&#x0D; mengetahuikualitas, batugampingserta reserves and resources geotechnical model based on&#x0D; the geological model. Geotechnical models also determined based on the model of rockmass used&#x0D; slope stability analysis as a model to design the mine pit. The methods used&#x0D; in this research include field work in the form of observation of outcrops of rocks and&#x0D; develop the sample, as well as laboratory analysis in the form of analysis of petrographic analysis and XRF&#x0D; using the sample surface, analysis of physical and mechanical properties of the rock mass classification, as well as&#x0D; rocks based on Geological Strenght Index (GSI) uses a secondary data in the form of core data&#x0D; drilling. Analysis of the stability of slopes in this study using the method of limit equilibrium&#x0D; (limit equilibrium method). Interpretation and correlation of data indicating that the drilling core location&#x0D; stratigraphic research is composed by three units of rock: limestone, batulempung, as well as&#x0D; sandstones. XRF analysis results and modeling geology suggests the quality of limestone meet&#x0D; cement raw material standards as to the amount of 13,180,000 tons of limestone resources. The geometry of the slope resulting from the analysis of the stability of slopes of which are: single slope height of 10 meters,&#x0D; the angle of slope of a single 80-degree slope, the slope of the overall 48 degrees, 50 degrees, 60 degrees, 54&#x0D; degrees, the wide level of 8.31 meters. Limestone reserves estimation is determined only on the basis of&#x0D; consideration of the mine pit design and ultimate pit limit which is limited by the territory of IUP. Backup&#x0D; tertambang (mineable reserve) limestone amounted to 7,477,000 tonnes.

An Agent-Based Simulation of Deep Foundation Pit Emergency Evacuation Modeling in the Presence of Collapse Disaster

With the gradual expansion of high buildings and underground spaces, deep foundation pits have been widely used in these engineering projects, but if they are not well-designed, safety problems occur. Proper deep foundation pit design requires proper exit distribution. However, calculating an adequate number of exit distributions for evaluation is difficult due to the numerous influential factors existing in the deep foundation pit environment. To this end, this paper presents a prototype of a decision-making system that uses agent-based modeling to simulate deep foundation pit evacuation in the presence of collapse disaster. By modeling the collapse occurrence process and agent escape process, an agent-based evacuation model is built, and a modified simulation-based particle swarm optimization algorithm is used to solve the optimization problem of exit distribution. Extensive experiments are conducted to verify the system, and the results show that the system provides a feasible framework for deep foundation pit evacuation.

Appraisal of Commonly used Mine Planning and Design Software in Ghanaian Surface Mines

Mine planning and design software improve productivity at every stage of a mine’s life and simplify mine planning and design processes so that a given deposit can be mined safely and economically. This study was set out to appraise Surpac and MineSight as the commonly used mine planning and design software in most Ghanaian surface mines. Questionnaires were administered to users in seven (7) producing mines using seven (7) appraisal criteria which include: ease of installation/configuration; user friendliness; performance capability; customisation (scripting) capability; compatibility with other software; cost effectiveness; and vendor support. Secondary data from Abosso Goldfields Limited (AGL) was used to plan and design AGL’s Huni pit using the two software to validate responses from the questionnaire administration. This enabled a comparative assessment of the strengths and weaknesses of the two software to be done. Surpac was ranked ahead of MineSight in all the seven (7) appraisal criteria, except for performance capability. The two software during the validation process gave good solid model volume and tonnage estimates but had little differences in the volumes and tonnages of partials. Surpac showed strength in installation and learning, block modelling, and partials extraction and estimation whilst MineSight showed strength in multiple user flexibility, pit design, and solid model creation and estimation. Recommendations to improve the two software have been offered as part of the study and a careful consideration of Datamine is suggested as they are making inroad into the Ghanaian market especially with their underground modules. Keywords: Mine Planning and Design, Surface Mining, Mining Software, Surpac, MineSight, Datamine

A Basic Study on Shock Resistant Design for Explosion Pit

The mechanism of damage on the structure of an explosion pit which belongs to the Institute of Pulsed Power Science, Kumamoto University is investigated. Investigated is the mechanism of damage on the structure of an explosion pit which belongs to the Institute of Pulsed Power Science, Kumamoto University. Here, three-dimensional model with square opening (door) is used to simulate by numerical simulation. The numerical result with the actual egg-type model implies that firstly the cracks occurred at the corners of the door and grew larger. In addition, the numerically simulated results with a spherical form model are also demonstrated to study on optimizing the design of an explosion pit.

Stormwater infiltration capacity of street tree pits: Quantifying the influence of different design and management strategies in New York City

Street trees are abundant in the urban landscape and provide many ecosystem services including stormwater management. For trees housed within tree pits, the ability to mitigate stormwater runoff can be modulated by the permeability of the soil within the tree pit itself. Thus, developing a better understanding of how tree pit design and management impact soil permeability can be important to quantifying, and potentially improving, the stormwater benefits of street trees. To this end, water infiltration rate was measured at forty tree pits representing the variety of physical conditions commonly seen in New York City, including the presence or absence of a tree pit guard, the size of the tree pit, the size of the tree, the presence or absence of ground cover planting, the presence or absence of mulch, and the elevation of the pit’s soil surface relative to the sidewalk. An initial analysis of results first tested the impact of each physical condition on infiltration rate individually. Genetic programming was then used to investigate interactive effects between the physical conditions, and to develop a statistical model that captured 66% of the variability in the observed infiltration rate using simple physical features of a tree pit. Results showed that the most significant factor influencing the infiltration rate was the presence of a guard around a tree pit, with guarded tree pits having higher infiltration rates. Additionally, higher infiltration rates in guarded pits were associated with larger pit areas, built-up surface elevations (binary) and the combined presence of ground cover planting (binary) and mulch (binary). Tree size, as measured by circumference at breast height, was found to be a less significant indicator of the infiltration rate. The statistical model, together with the study measurements, can be used to estimate the stormwater benefits of different tree pit management strategies, inform designs for improved stormwater management, and help identify useful observations or measurements for a street tree census.

Cutoff grade optimization in open pit mines using genetic algorithm

The fundamental objective of production planning is to create a mechanism for the implementation of the mining cutoff grades and short-term production planning. One of the most important parameters in open pit design is a determination of the optimal cutoff grade. Optimum cutoff grade results in maximizing profits or maximizing the net present value. Given that in determining the cutoff grade with the goal of maximizing profits, a constant value is obtained for the entire life of the mine. The annual income of the mine will be the same throughout its lifetime, and the time value of the money has not been neglected; which is the main disadvantage of this optimization process. While in optimization with the goal of maximizing net present value, the optimal value will be a function of the time and will be greater in the early years of the mine and will gradually decrease. Optimization of cutoff grades with the aim of maximizing the net present value over the life of the mine is important due to its dependence on the economic parameters, the design of the open pit mining and fundamental issues. Maximizing the net present value is a nonlinear programming problem. To determine the optimal cutoff grade Lane method is commonly used. Lane provided his method to determine the optimal cutoff grade by considering factors such as the capacity of the mine, concentrator and load capacity of the treatment plant, the time value of money and distributing grade. The procedure of the Lane method for cutoff grade calculation is complicated and time-consuming. Considering the widespread use of heuristic methods in optimizing parameters, In the present study genetic algorithm, which is a smart algorithm, is used to determine the optimal cutoff grade. In this paper, we compare the efficiency of the genetic algorithm and Lane's theory in optimizing the degree of limit based on maximizing the net present value. Using separate programming based on the genetic algorithm and considering the capacity limitations and the proportion between the parameters of mining to smelter and refining in the mine is done. For this purpose, consider precision of 0.001%, optimum cutoff grades, the amount of output per unit and the net present value are calculated. The optimum cutoff grade at the beginning of the life of the mine is equal to 0.506% and at the end of the life of the mine to 0.222% using the genetic algorithm. Using the Lane model at the beginning of the life of the mine the optimum cut-off grade from 0/503% to 0/220% reaches at the end of the mine's life. The net present value of earnings over a lifespan of 7 years mine in the genetic algorithm and Lane model is $ 93,467,914 and $ 94,408,000 respectively. Also, the amount of mining, the amount of processing and the amount of refinery obtained by the genetic algorithm method are compared to the Lane model. The results of the research indicate high speed and very low error of genetic algorithm and also a convergence of results with the Lane method.

An inverse analysis of weak structural plane parameters for a limestone foundation pit based on critical stability

The article uses the Fast Lagrangian Analysis of Continua in 3 Dimensions (FLAC3D) to make an analysis of the deformation characteristics of the structural plane, which is based on a real rock foundation pit in Jinan city. It makes an inverse analysis of the strength of the surface structure and the occurrence of the parameters by Mohr-Coulomb strength criterion value criterion in the way of numerical simulation, which explores the change of stress field of x-z oblique section of pit wall and the relation between the exposed height of structural plane and the critical cohesion, the exposed height and critical inclination angle of the structure surface. We can find that when the foundation pit is in the critical stable state and the inclination angle of the structural plane is constant, the critical cohesive force of the structural plane increases with the increase of the exposed surface height. And when the foundation pit in the critical stability of the situation and the structural surface of the cohesive force is constant, the structural surface exposed height increases and the structural angle of inclination is declining. The conclusion can provide theoretical basis for the design and construction of the rock foundation pit with structural plane.

Analysis of influence of seepage on stability of foundation pit

Numerical analysis is executed to deep foundation pit by using the finite element software. In combination with the site data, the consequences with the consideration of groundwater seepage are contrasted to the consequences without the consideration of groundwater seepage including the stability of the foundation pit. The analysis indicates that the result with the consideration of seepage is relatively close to the site data. Compared with the result without consideration of groundwater seepage, the maximum horizontal offset of the pile increases approximate 5mm and the location of the maximum horizontal displacement moves 2m down. So seepage is harmful to the retaining structure of foundation pit and should be considered in the design of foundation pit.

Zoning Supporting Design of Deep Foundation Pit Based on Controlling Deformation of Surrounding Buildings

According to the deep foundation pit of a spatial dimension in Shijiazhuang, the retaining and protection structure of pile and anchor cable is selected because of property of the soil layer. The interaction between the support system and the surrounding buildings is analyzed by the finite difference method, on this basis, according to the deformation of surrounding environment and the stability requirement of slope, the deep foundation pit is made zoning supporting design. When there is a building on the outside of foundation pit wall and the building is located in the middle side of the slope wall, the effect of building on horizontal displacement of foundation pit is mainly happened in the middle of the slope wall, and the range is (0.22~0.78) L (L is the length of the foundation pit) or 1.85A (A is the length of the building along the direction of the pit). The settlement and different settlement of the building foundation can be controlled by increasing the stiffness of the retaining structure, such as increasing the diameter of pile or reducing the spacing of pile. When reducing the diameter of pile or increasing the spacing between the piles in the west side of the slope, the deformation and different deformation of the area are obviously reduced, so as to meet the requirements for the deformation of the underground pipelines outside the slope wall.

The Slope Instability Emergency Rescue Analysis When the Neighboring Deep the Foundation Pit Retaining Structure Construction

An excavation was introduced in this paper both side slope leads to large deformation analysis of the disaster and monitoring. By analyzing the known not to identification, both the slope reinforcement is a major cause of slope deformation occurred, slope construction safety and construction time limit for a project into consideration, determine the slope to the slope toe bulldozing back pressure, the building of a miniature pile reinforcement before emergency measures, to strengthen the segment foundation pit design, and encryption of foundation pit and slope monitoring. Conclusion analysis of monitoring data before and after the disaster, the slope to take the temporary settlement of construction control has good effect; not completely temporary slope reinforcement to ensure slope stability, but unable to control deformation of sustainable development. Displacement on the top of the foundation pit supporting structure is affected by both side slope displacement.

English

Inadequate information on physiochemical properties of faecal sludge leads to inappropriate design of pit emptying devices and poor faecal sludge disposal contributing to environmental pollution. This study undertook a critical analysis of physiochemical properties of feacal sludge that influence design and performance of pit emptying devices and faecal sludge disposal for improved faecal sludge management in urban slums. The physiochemical properties determined were; Moisture content (MC), ash content (AC), total solids (TS), volatile solids (VS), nitrogen (N), phosphorous (P), potassium (K) and pH. Samples were collected from 55 unlined pits at depths of 0, 0.5, 1 and 1.5 m from pit surface. The unlined pits in this study were purposively selected from slums in Kampala. A sample of 300 g was sucked from each depth using a manual sampling tool and emptied into a plastic container. The container was then wrapped in a black plastic bag and transported in cooler boxes to the lab for analysis. The properties were subjected to Principal Component Analysis to isolate the critical parameters that affect pit emptying and faecal sludge disposal. The mean results were: MC of 86 &plusmn; 8.37%; TS of 0.14 &plusmn; 0.08 g/g wet sample; VS of 0.73 &plusmn; 0.32 g/g dry sample; pH of 8.0 &plusmn; 1.5; AC of 0.35&plusmn; 0.18 g/g dry sample; TN of 3.5 &plusmn; 0.08%; K of 2.2&plusmn; 0.13%&nbsp; and P of 1.4&plusmn; 0.05%. It was concluded that physiochemical properties in Ugandan pits are comparable to those of global pits except for the acidic conditions at top surface in some pits, and higher moisture content in pits due to the high water table. PCA results showed that moisture content and total solids affected pit emptying techniques while fractional content of N, P and pH affect most choice of faecal sludge disposal technique. &nbsp; Key words: Pit latrine, faecal sludge management, developing countries, physiochemical properties, pit emptying.