abstract: Existing robotic excavation research has been primarily focused on lunar mining missions or simple traffic control in confined tunnels, however little work attempts to bring collective excavation into the realm of human infrastructure. This thesis explores a decentralized approach to excavation processes, where traffic laws are borrowed from swarms of fire ants (Solenopsis invicta) or termites (Coptotermes formosanus) to create decision rules for a swarm of robots working together and organizing effectively to create a desired final excavated pattern. First, a literature review of the behavioral rules of different types of insect colonies and the resulting structural patterns over the course of excavation was conducted. After identifying pertinent excavation laws, three different finite state machines were generated that relate to construction, search and rescue operations, and extraterrestrial exploration. After analyzing these finite state machines, it became apparent that they all shared a common controller. Then, agent-based NetLogo software was used to simulate a swarm of agents that run this controller, and a model for excavating behaviors and patterns was fit to the simulation data. This model predicts the tunnel shapes formed in the simulation as a function of the swarm size and a time delay, called the critical waiting period, in one of the state transitions. Thus, by controlling the individual agents' behavior, it was possible to control the structural outcomes of collective excavation in simulation. To create an experimental testbed that could be used to physically implement the controller, a small foldable robotic platform was developed, and it's capabilities were tested in granular media. In order to characterize the granular media, force experiments were conducted and parameters were measured for resistive forces during an excavation cycle. The final experiment verified the robot's ability to engage in excavation and deposition, and to determine whether or not to begin the critical waiting period. This testbed can be expanded with multiple robots to conduct small-scale experiments on collective excavation, such as further exploring the effects of the critical waiting period on the resulting excavation pattern. In addition, investigating other factors like tuning digging efficiency or deposition proximity could help to transition the proposed bio-inspired swarm excavation controllers to implementation in real-world applications. / Dissertation/Thesis / Masters Thesis Mechanical Engineering 2018

The happening of life can reduce you in to a machine where its only focus is on the relentless rationing of energy. When down on the deep sea plane, not much work gets done. But; I write everything down. Because of my fear of forgetting. I forget anyway, so it might seem pointless. I leave the notes, tucked away behind my back while trying to get out of bed, get dressed, answer an email, speak and understand language, remembering the now. Why take notes that does not get read for weeks, months, years or never. Halfway through my masters I realized its importance; my practice contains of the excavation of my own archive. The words of time has always been my foundation, my point of departure; this essay is surrounded of the past but exists in the now. "All this time with a different pulse. Maybe it is something inside of the water."

In view of the recent catastrophes associated with deep excavations, there is an urgent need to provide vital guidelines on the design of the construction process. To develop a simple tool for predicting ground deformation around a deep excavation construction for preliminary design and decision-making purposes, small scale centrifuge models were made to observe the complicated mechanisms involved. A newly developed actuation system, with which the construction sequences ofpropping could be implemented, was developed, the new procedures were proven to give more realistic initial ground conditions before excavation with minimal development of pre-excavation bending moment and wall displacement. Incremental wall deformation profiles generally followed the O'Rourke cosine bulge equation and a new deformation mechanism was proposed with respect to wall toe fixity and excavation geometry. Validation of the conservation energy principle was carried out for the undrained excavation process. The total loss of potential energy was shown to be balanced by the total work done in shearing and the total elastic energy stored in structures with an error term of 30%. An improved mobilizable strength method (MSD) method using observed mechanistic deformation patterns was introduced to calculate the displacement profile of a multi-propped undrained excavation in soft clay. The incremental loss in potential energy associated with the formation of settlement toughs was balanced by the sum of incremental storage of elastic energy and the energy dissipation in shearing. A reasonable agreement was found between the prediction by the MSD method and the finite element results computed by an advanced MIT-E3 model for wall displacements, ground settlement, base heave and bending moment on fixed base walls. For cases of excavations supported by floating walls, the effect of embedded wall length, depth of the stiff layer, bending stiffness of wall and excavation geometry and over-consolidation ratio of soils were found to have a influence on the maximum wall deflection. In general, the predictions fell within 30% of the finite element computed results. A new chart Ψ versus normalized system stiffness was used to demonstrate that MSD could correctly capture the trend of wall displacements increasing with the ratio ofexcavation depth to depth of stiff layer, which could be controlled by increasing wall stiffness for very stiff wall system only. The incorporation of a simple parabolic curvequantifying small strain stiffness of soil was proven to be essential to good ground movement predictions. A new dimensionless group has been defined using the MSD concepts to analyze 110 cases of excavation. The new database can now be used to investigate the relationship between structural response ratio S and soil-structure stiffness ratio R where this is shown on log-log axes to capture the enormous range of wall stiffness between sheet-piles and thick diaphragm walls. Wall stiffness was found to have a negligible influence on the magnitude of the wall bulging displacements for deep excavation supported by fixed-based wall with stiffness ranging from sheet pile walls to ordinary reinforced concrete diaphragm walls, whereas excavations supported by floating walls were found to be influenced by wall stiffness due to the difference in deformation mechanisms.

The testing undertaken for this dissertation is intended to help quantify the various time-dependant deformation processes around typical deep level hard rock tabular excavations. Three mechanisms were investigated and two different hard rock types, Ventersdorp Lava and Elsburg Quartzite were used. Uniaxial compression creep studies were done as the first part of the study followed by shear creep studies on discontinuities where crushed lava and crushed quartzite as well as a natural gouge were used as infilling. An important conclusion made is that the relationship between grain size and infilling thickness is more important than previously might have been assumed. The last part of the study consisted of triaxial post-failure relaxation tests. As far as could be determined, this is the first time triaxial post-failure tests were attempted, particularly on typical South African hard rocks. An important finding of this study is that during compression creep as well as during triaxial post-failure relaxation the amount of energy dissipated for the lava is significantly less than for quartzite. For mines operating at great depth (more than 2000m) the implication is that the rock material might relax much more slowly than might have been assumed and this means that after failure the rock mass continues to store large amounts of strain energy. This study provides the first data available for energy change calculations in fractured rock masses. Three mechanisms of time-dependant deformation were quantified providing valuable data for numerical investigations. / Dissertation (MSc (Mine Strata Control))--University of Pretoria, 2006. / Mining Engineering / unrestricted

On the Island of Gotland, there is a phenomenon called grinding grooves, Sw. slipskåror. They occur in bedrock and boulders. About 3600 are known on the island today and having a length of less than half a meter to over one meter. Their purpose was unknown to the scientific community as well as their age. The directions of some 1250 Gotlandic grinding grooves, measured by the author shows there is a correlation to astronomical orientations. An archaeological excavation carried out by the author at a stone with grinding grooves gave some crucial results. The grinding groove phenomenon occurs in some other places in the world as well. In South-West of Sweden, there are quite many in a few places. They are, however shorter and have another appearance because they are more curvature than the Gotlandic ones. Their purpose and age are unknown as well. In France, there are many places with grinding grooves, Fr. polissoirs. Their appearance is more similar to the Gotlandic ones than those in the Swedish mainland. They are supposed to be Neolithic.  In Africa and Australia, there are places with different kinds of carvings in stones. Some resemble those mentioned above, more or less. The difference between grinding grooves and other phenomena is floating.  They are sometimes associated with the circular indentations called cup marks. There are different explanations, and some are supposed to be marks from creating stone tools, while the cult is the explanation to others.

M.Sc. (Eng.),Faculty of Engineering and the Built Environment, University of the Witwatersrand, 2012 / Mining is a sensitive business that yields high returns and at the same time is associated with high risk of injuries/fatalities and potential losses of revenue. There is increasing intolerance for injuries and fatalities by governments and the other stakeholders involved in the mining business often resulting in mine closures and revenue loss. Chief among the mining risks is the occurrence of rockfalls where people work and access. The rockfalls are bound mainly by joints that intersect the rockmass thereby forming rock blocks that may fall once an excavation has been created. There are many methods that have been used over time to predict the occurrence of rockfalls. More recently probabilistic methods have gained more ground over deterministic methods. The properties of the joints that are identifiable on exposed excavations are the main inputs used in simulating rockfalls. To date there has been little work that has been done to compare predicted rockfalls to actual rockfalls. This dissertation presents a practical method for collecting rockfall and joint data in the stope hangiwall at two mines in the Bushveld Complex. The joint data has been used in simulating rockfalls using JBlock (a probabilistic keyblock stability programme). A comparison between simulated rockfalls and mapped rockfalls has been presented. Based on this comparison, a number of iterations were done to calibrate the JBlock results until near realistic rockfalls were achieved. Three case studies have been conducted to investigate the effectiveness of different stope support systems in reducing rockfall. The potential losses and injury risk associated with the different support systems have been quantified for all the individual rockfalls. In general the rockfall frequency is directly proportional to the risks associated with the rockfalls. Through this research it has been demonstrated that it is possible to use joint data found on excavation surfaces to statistically predict the occurrence of potential rockfalls in similar ground conditions. The optimum support system that has minimum injury and cost risk can also be selected from a comparison of a number of support systems. Armed with this information, rock engineers can now make strategic decisions versus the existing common tactical approach.

The mining industry is an important part of the society’s green transition by providing the metals and minerals necessary for an increased electrification. One downside of the mining industry is that the mining operation typically contaminates the land to some degree. Excavation-and-refill is a traditional remediation approach for soil contaminations, a method that often could be very expensive and cause a large amount of greenhouse gas emissions. This study aims to compare different excavation strategies to find out how they affect the sustainability dimensions and the climate. This is done by using two measuring tools: SAMLA for contaminated sites and Carbon footprint of remediations and other groundworks. The results show that the largest greenhouse gas emissions occur when transporting the contaminated soils to the designated landfill. The different excavation approaches have a positive impact primarily on the ecological and social sustainability dimensions, including reducing the risks for the environment and people’s health. To make excavation-and-refill remediations more sustainable the main focus should be towards the largest contributor of greenhouse gas emissions, together with developing the knowledge regarding the climate impact of remediation methods and to improve the knowledge of alternative, more sustainable, remediation methods. Implementation of environmental regulations focusing on remediations could also be an important factor in the transition towards more sustainable remediation methods.

An alternative to the displacement finite element method, the hybrid stress model, is applied to problems in geomechanics. A two-dimensional finite element procedure based on the hybrid stress model is developed for simulation of construction sequences including underground and surface excavations. In this procedure, an eight-node isoparametric element is employed. In the analysis, the effect of soil-structure interaction is incorporated by using a special interface element for behavior at the contact between two different materials. In the elastic-plastic analysis, the Drucker-Prager model is used as a constitutive law. In order to verify the computer program and to examine the accuracy of the hybrid stress model, several problems such as a beam, a plate with circular hole, and footings are analyzed, and the results are compared with those from the displacement method and closed-form solutions. The proposed procedure for simulation of excavation is verified by performing an excavation in linear elastic material. Finally, two field cases of excavation are solved and the results are compared with the displacement method and the field observations. It is believed that the proposed (stress) hybrid method can have significant potential of application for various problems in geomechanics, and it can be particularly appropriate for a situation where computation of stresses is important. / Ph. D.

No / The University of Bradford was constructed in the 1960s, following the demolition of Victorian streets, houses, and local community buildings. An on-campus archaeological excavation took place in 2021 as a result of Covid-19 restrictions. Using a variety of archive sources, the results of the Dig led to an armchair exploration of both former Victorian residents and also the social history of the former community. This reflective piece documents the archive journey taken by someone who is not an archaeologist and touches upon the experiences of heritage attachment. / University of Bradford, School of Social Sciences Research Fund

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