Triaxial Tests Research Articles

Dynamic mechanical properties and damage constitutive modelling of paste phyllite under triaxial impact testing

Dynamic mechanical properties and damage constitutive modelling of paste phyllite under triaxial impact testing

Numerical Study of Cone Penetration Tests in Lunar Regolith for Strength Index

The cohesive properties of lunar regolith, combined with a low-gravity environment, result in it having a distinct mechanical behavior from sandy soil on Earth. Consequently, empirical formulas derived from cone penetration tests (CPTs) for calculating the shear strength parameters of Earth’s sand cannot be directly applied to lunar regolith. This study utilized the three-dimensional discrete element method (DEM) to numerically simulate triaxial shear tests and cone penetration tests in a lunar environment. The particle contact model for lunar regolith in the discrete element method (DEM) simulation incorporated the hysteresis effect of van der Waals forces, thereby simulating the cohesive properties of lunar regolith in a lunar environment. We proposed a relationship for calculating the shear strength index of lunar regolith based on normalized cone tip resistance using the results from triaxial and CPT simulations and referencing empirical formulas derived from ground-based CPT data. The results of this study provide a valuable reference for future lunar CPTs.

Effect of High-Stress Levels on the Shear Behavior of Geosynthetic-Reinforced Marine Coral Sands

As an important construction material, the mechanical and deformation properties of marine coral sand determine the safety and stability of related island and coastal engineering construction. The porous and easily broken characteristics of coral sand often make it difficult to meet engineering construction needs. In particular, coral sand undergoes a large amount of particle breakage under high-stress conditions, which in turn negatively affects its mechanical and deformation properties. In this study, the macro- and micro-mechanical behavior of geosynthetic-reinforced coral sand under high confining pressure was investigated and compared with unreinforced cases using the three-dimensional discrete element method (DEM), which was verified by indoor triaxial tests. The results showed that the stress–strain responses of unreinforced and reinforced coral sand under high confining pressure showed completely different trends, i.e., the hardening tendency shown in the reinforced case. Geosynthetic reinforcement can significantly inhibit the stress–strain softening and bulging deformation of coral sand under high confining pressure, thus improving the shear mechanical performance of the reinforced sample. At the microscopic scale, high confining pressure and reinforcement affected the contact force distribution pattern and stress level between particles, determining the macroscopic mechanical and deformation performance. In addition, the breakage of particles under high confining pressure was mainly affected by shear strain and reinforcement. The particle fragment distribution, particle gradation, and relative breakage index exhibited different trends at different confining pressure levels. These breakage characteristics were closely related to the deformation and stress levels of unreinforced and reinforced samples.

Pavement performance over deep trenches backfilled with recycled aggregates under different compaction efforts

Insufficient understanding of the stress-strain behavior of pavements built over backfilled trenches, particularly with recycled aggregates, often leads to over-design or over-compaction, raising costs and project delays. This research investigates how compaction levels during backfilling impact the pavement performance over these trenches. Various recycled material mixtures, both unbound and cement-treated, are compared with conventional crushed rock. Investigations included repeated load triaxial (RLT) tests, microstructural analysis with Scanning Electron Microscopy (SEM), environmental assessments, and modeling with FlexPAVETM, a pavement response and performance analysis software. RLT test results were incorporated into the FlexPAVETM models by utilizing established constitutive resilient modulus models. Stress-strain responses of pavements over recycled aggregate backfill, compacted with standard and modified Proctor efforts, were compared with those over crushed rock and natural clay subgrades. Outcomes revealed that the standard compaction energy was sufficient for the desired performance. Fatigue and rutting strains with recycled mixtures closely resembled those with crushed rock, making them viable green alternatives. Pavements over backfilled trenches exhibited 1.5 and 1.8 times longer fatigue and rutting lives, respectively, than those over natural clay subgrades.

Hyperbolic Evolutionary Model for Equivalent Modulus of Sand and Characterization of Its Cyclic Hardening Properties

The cyclic hardening characteristics of soil hold significant importance for understanding its performance, and the evolution of the deformation modulus serves as a crucial indicator of the hardening properties. Deformations can be classified into elastic and plastic deformations and expressed in terms of modulus; however, their roles in the cyclic hardening process remain unclear. In this study, the elastic and plastic moduli were separated using the hyperbolic evolutionary model, which characterized the evolutionary properties of both to reflect the cyclic hardening process. A series of cyclic triaxial shear tests was conducted utilizing ISO sand and emery as test materials. A hyperbolic evolution model relating the equivalent modulus to the number of cycles was established, and the effect of various test conditions on the elastic modulus is discussed. The results indicate that: (1) the relationship between the equivalent modulus and the number of cycles is hyperbolic; and (2) the parameters k and b of the hyperbolic evolution model correspond to the elastic and plastic moduli, allowing for the separation of the evolution of both from that of the deformation modulus. The hyperbolic evolution model of the equivalent modulus proposed in this paper offers new insight into the cyclic hardening properties of sand.

Long short term memory networks for predicting resilient Modulus of stabilized base material subject to wet-dry cycles.

The resilient modulus (MR) of different pavement materials is one of the most important input parameters for the mechanistic-empirical pavement design approach. The dynamic triaxial test is the most often used method for evaluating the MR, although it is expensive, time-consuming, and requires specialized lab facilities. The purpose of this study is to establish a new model based on Long Short-Term Memory (LSTM) networks for predicting the MR of stabilized base materials with various additives during wet-dry cycles (WDC). A laboratory dataset of 704 records has been used using input parameters, including WDC, ratio of calcium oxide to silica, alumina, and ferric oxide compound, Maximum dry density to the optimal moisture content ratio (DMR), deviator stress (σd), and confining stress (σ3). The results demonstrate that the LSTM technique is very accurate, with coefficients of determination of 0.995 and 0.980 for the training and testing datasets, respectively. The LSTM model outperforms other developed models, such as support vector regression and least squares approaches, in the literature. A sensitivity analysis study has determined that the DMR parameter is the most significant factor, while the σd parameter is the least significant factor in predicting the MR of the stabilized base material under WDC. Furthermore, the SHapley Additive exPlanations approach is employed to elucidate the optimal model and examine the impact of its features on the final result.

Faulting by the 2023 great earthquakes of Türkiye and associated stress field and its effects on built environment

Abstract Background Faulting induced by earthquakes and its analysis are of great importance for areas with high probability of earthquakes. However, there has been no particularly effective methods to evaluate the damage and applicable solutions for recovery. In this paper, the damage from Türkiye earthquakes is investigated by authors, which has important theoretical significance and practical value. On 6 February, 2023, two successive earthquakes with magnitudes (Mw) of 7.8 (called Pazarcık earthquake) and 7.6 (Ekinözü earthquake) occurred in the south-eastern part of Türkiye. The total length of the surface ruptures was more than 500 km long and resulted in striations reflecting the sinistral faulting and extensive ground deformations. In this study, the authors present the outcomes of the investigations on the surface ruptures, their characteristics, stress field associated with both earthquakes, shear strength property of fault segments and the damaging effects on various structures and made some recommendations with the purpose of how to build structures in active fault zones and decrease the negative effects of faulting on structures. Results Besides summarizing the main characteristics of the world-shaking Kahramanmaraş earthquake doublet in southeast Türkiye in 2023, this study described the main features of the surface ruptures, their relation to the inferred crustal stresses in Türkiye, and the damaging effects on the major engineering structures. The observations and inferences are of great significance for understanding the causes of earthquakes and future seismic risk assessment. Various laboratory experiments were performed on the samples of fault gouge gathered from the sites of surface ruptures and these experimental results provided very valuable quantitative information on the constitutive models of the fault zones. The observations clearly showed that it is almost impossible to prevent damage on structures due to surface ruptures, if certain engineering principles such as increasing higher ductility, lowering gravitational center and/or the implementations of raft foundations are followed. Conclusions The stress state inferences obtained from the striation of the fault surface ruptures as well as from the focal plane solutions are expected to be useful to evaluate the regional stress state of the earthquake region. Assessments indicated that the stress states in Arabian plate and Anadolu platelet are different from each other. However, in-situ direct stress measurement techniques would be quite useful to validate the stress state inferred in this study. The laboratory experiments on samples gathered from the fault outcrops of the earthquakes using direct shear tests, stick-slip tests as well as conventional tensile, compressive and triaxial tests provided the quantitative values for the parameters of constitutive laws for fault zones, which can be utilized in the numerical simulation of earthquakes. If a fault break happens to be just passing underneath the structures, it is almost impossible for mankind to prevent the damage to structures. However, the authors made some recommendations to reduce the negative effects of fault ruptures on structures. These recommendations are such that the structures should be built as ductile and redundant structures with lower center of gravity and raft foundations. Dam construction should be on active faults should be avoided. If they are to be built for whatever reason, they should be of rock-fill type. As tubular structures and tunnels would be generally subjected forced displacement field, it is recommended to utilize flexible joints, segmented and enlargement to deal such displacement fields.

Geosynthetic-stabilized aggregate: quantitative modulus evaluation via Bender Element

Geosynthetics, mainly geogrids and geotextiles, are commonly used to mechanically stabilize unbound aggregate layers in paved road applications. They provide lateral restraint to aggregates to initially increase the layer modulus during construction and minimize its time-dependent decrease under vehicular traffic loading. Different types of geosynthetics may provide different improvement mechanisms and stiffness enhancement levels. Quantitative evaluation of various stabilization geosynthetics is presented herein to compare modulus improvement trends and help incorporate geosynthetic benefits into state-of-the-art mechanistic-empirical (M-E) pavement design procedures. Five geogrids (three extruded, one woven, and one welded) and two geotextiles (one woven and one nonwoven) were studied with a dense graded aggregate in laboratory triaxial testing. Geosynthetics were placed at specimen mid-height and three pairs of Bender Element (BE) sensors were placed at various heights above the geosynthetic to collect shear waves and quantify the degree of mechanical stabilization during resilient modulus testing. While resilient moduli did not distinguish effectiveness of different geosynthetics, shear wave measurements could clearly show local stiffness increases achieved with geosynthetic inclusions. Meanwhile, trends observed in shear modulus profiles at various distances from the geosynthetic, when compared to that of control specimen, properly established the modulus enhancement level achieved in mechanical stabilization with geosynthetics.

Evaluation of Steel Slag as a Sustainable Alternative Aggregate for Railway Ballast: A Shakedown Theory-Based Approach

Recent advancements in railway construction have emphasized environmental sustainability, integrating considerations of environmental impact into the planning and execution of infrastructure projects to reduce costs and mitigate adverse effects. This study investigates the use of steel slag as a sustainable alternative for railway ballast, grounded in shakedown theory. The characterization of the aggregates was performed in accordance with NBR 5564 and AREMA standards, confirming that the material meets most requirements. The mechanical behavior of the ballast was analyzed under cyclic loading conditions, assessing permanent deformation and the material’s ability to achieve stability (shakedown). Triaxial tests with repeated loading simulated real railway conditions, applying vertical stresses up to 600 kPa and confining pressures ranging from 35 to 200 kPa. The results indicate that steel slag aggregates exhibited promising performance, with seven specimens achieving stable deformation levels, characterized by residual deformations of less than 2.5 mm. Notably, these specimens approached deformations on the order of 10−7, indicating stability under cyclic loading. Furthermore, a comparative analysis of shakedown criteria proposed by various authors revealed variations in limits for granular materials, enhancing the understanding of steel slag aggregate behavior. The experimental results were validated through numerical simulations conducted with Systrain software 2.0, which simulated a loading condition of 32.5 tons per axle, confirming the observations with maximum principal stresses ranging from 166 to 184 kPa in the ballast. The analysis showed that steel slag aggregates can withstand stress levels higher than those of granodiorite, reinforcing their viability as a sustainable alternative for railway ballast.

Evaluating Rock Brittleness Through a Novel Statistical Damage Theory-Based Index: A Case Study on Sandstones

Evaluating the brittleness of rocks or rock masses is a fundamental problem in geotechnical engineering. This study proposed a new index that expresses brittleness as the rate of damage development in rock. The brittleness index was derived from statistical damage theory. It depends on the four material parameters, i.e., the peak strain, peak strength, Poisson’s ratio and elastic modulus. The validity of the proposed brittleness index was confirmed through two case studies, including triaxial compression test results for coals subjected to varying confining pressures and for sandstones at various temperatures. Uniaxial compression experiments were then performed on rock-like materials to examine the effects of model size and joint dip angle on rock brittleness using the proposed brittleness index. Results show that the brittleness of the jointed specimens varies in a complex pattern with the model size and joint dip angle. Generally, the brittleness index initially reduces and then grows with the increasing joint dip angle, and larger specimens tend to be more brittle. Furthermore, large specimens containing horizontal or vertical joints are particularly susceptible to brittle damage. The proposed brittleness index has merits such as a clear physical meaning and simple expression, making it a valuable tool for evaluating rock brittleness.

Mechanical properties and energy evolution of outburst coal seams under different load regimes

AbstractCoal elasticity and gas expansion are important factors for coal and gas outburst. During the outburst process, the elastic strain energy of coal is mainly released from the stress region, and the gas expansion energy near the working face is larger, and it is not a continuous release process. To reveal the mechanical characteristics and energy evolution of outburst coal seam, uniaxial and triaxial compression tests were carried out on outburst coal seam samples under different loading methods. The experimental results show that the elastic characteristics become more obvious with the increase of loading rate, the peak strain increases, the elastic modulus is linearly related with the loading rate，and the overall degree of fragmentation increases with the increase of loading rate, which is consistent with the severity of macroscopic coal failure. The failure mode of coal under uniaxial compression conditions is often manifest as brittle failure. The strength characteristics of coal under different loading rates comply with the Mohr‐Coulomb criterion, and the peak strength is linearly related to the failure time and loading rate. With the increasing confining pressure causes the failure of coal samples to transition from ductile to brittle, and the failure mode develops from local shear to overall splitting. The elastic energy evolution curve is consistent with its stress‐strain curve. With the increase of confining pressure, the limiting elastic energy and peak total energy increase in a quasi‐linear manner. The accumulated limit elastic energy plays an important role in the failure of coal samples, and the macroscopic manifestation thereof is that the coal samples fail more severely under high confining pressure conditions than under low confining pressure conditions. The research results are of great significance for the comprehensive prevention and control of coal and gas outburst.

FEM Analysis on Isotropic Consolidation of Unsaturated Soils Using Ceramic Disks and Microporous Membrane Filters for Suction Control

Abstract Microporous membrane (MM) filters with a significantly thin thickness have recently been used as an alternative to ceramic disks for matric suction control in the axis-translation technique for element tests on unsaturated soils. Although researchers have highlighted some discrepancies in test results when ceramic disks and MM filters are used, the mechanism leading to these discrepancies has not yet been clarified. In this study, suction-controlled triaxial tests were first conducted on unsaturated completely decomposed granite using two filters. Then, it is natural to believe that the different thicknesses of ceramic disk and MM filters may significantly influence the suction equilibrium process of specimens. To clarify this issue, soil-water-air coupled finite element modeling was performed to simulate the consolidation process in triaxial tests as an initial/boundary value problem. In the numerical calculation, the influence of the void ratio on the water retention curve (WRC) of soil was properly considered by adopting a deformation-dependent WRC model. In particular, the ceramic disk and MM filter, along with the specimens, were modeled, and their differences in thickness were considered. The calculated results show that a nonuniform distribution of suction occurred in the ceramic disk, leading to greater drainage discharge of the specimens. In other words, the influence of the thickness difference between the MM filter and ceramic disk cannot be neglected. However, regardless of whether ceramic discs or MM filters are used, the uneven distribution of the state variables in the specimens may occur in the triaxial tests for unsaturated soils, which emphasizes the importance of assessing the soil tests using the present axis-translation technique as initial/boundary value problems.

Strength and dilatancy of an unsaturated expansive soil at high suction levels

A series of suction-controlled triaxial tests was conducted on Nanyang expansive clay to investigate the effects of dry density and suction on dilatancy and strength. The suction of the soil samples was controlled using a vapour equilibrium technique, with four suction levels ranging from 3.29 MPa to 198.14 MPa, where water retention is dominated by adsorption. The experimental results show that the tested soil exhibits a brittle failure mode under high suction, significantly distinguishing the hydro-mechanical behaviour of the soil at high suction from that observed at low suction. This brittle failure mode significantly increases the contribution of suction to peak strength compared to residual strength, causes the soil to fail before reaching the critical state, a phenomenon not observed in soils under high suction, and results in dilatancy caused by damage to the soil particle aggregates rather than particle rearrangement. The dilatancy data obtained from the triaxial tests reveal that significant soil dilatancy occurs during shear after reaching peak strength, with the maximum dilatancy angle increasing with suction and decreasing with confining pressure. However, the initial dry density has a negligible impact on the soil's dilatancy under high suction levels. This observation further supports that, for unsaturated soils under high suction levels, dilatancy is attributed to damage to soil particle aggregates rather than the rearrangement of soil particles.

Soil fluidisation induced by fine particles migration: Insights from the Shenzhen 2015 landfill landslide

Naturally completely decomposed granite (CDG) soil typically exhibits strain-hardening behavior under undrained shear conditions. Nevertheless, flow-type landslides are not uncommon in CDG landfills. This paper endeavors to address the observed contradiction by conducting a case study of the 2015 Shenzhen landslides. Based on field investigations, we propose a hypothesis for the initiation and evolution of flow-type landslides in CDG landfill slopes, termed ‘clay particle argillization, mud-water migration, and static liquefaction’. This hypothesis was verified by element-scale internal erosion tests and triaxial tests, and further elucidated by microscale particle analysis. It was observed that the internal erosion-induced removal of plastic fine particles and retention of low-plasticity fine particles from CDG soil promotes the sliding and reorganization of coarse granules under shear stress, thereby increasing the soil's susceptibility to fluidization under undrained conditions. The proposed hypothesis and experimental findings provide new insights into the instability and subsequent extensive runout of CDG landfills and analogous broadly graded landslides.

Application of Asaoka’s Method in Multistage Triaxial Compression Testing of Normally Consolidated Soils

Abstract Determination of shear strength parameters becomes a challenge when it is difficult to retrieve a minimum of three identical undisturbed soil specimens. In such a situation, multistage triaxial compression testing can be adopted using a single specimen. Multistage triaxial testing involves stage-wise consolidation and shearing at three confining pressures without the failure of the specimen until the last stage. A critical issue associated with multistage triaxial testing is the estimation of ultimate deviator stress and the corresponding pore pressure as the specimen was not allowed to reach failure in each stage. Conventionally, the failure stress state in each stage is computed by extrapolating the stress–strain and pore pressure–strain data to a finite strain by employing Kondner’s rectangular hyperbola model. However, it is reported in the literature that the aforementioned method often overestimates the deviator stress and pore pressure values. In this context, the present study investigates the suitability of Asaoka’s observational procedure for predicting these values at failure state. The validity of the proposed procedure is verified by comparing the ultimate deviator stress and pore pressure values obtained by analyzing the stress–strain data collected from the literature and by performing multistage triaxial testing on three reconstituted soil samples with that of the rectangular hyperbola method. From the results, it was observed that Asaoka’s method is more suited for predicting the shear strength parameters. It is believed that the proposed methodology would aid in obtaining the shear strength parameters of a soil from a single specimen by conducting multistage triaxial testing.

Impact of triaxial stress state at various pavement depths on the dynamic modulus of asphalt mixture

The mechanical characteristics of asphalt mixture are closely related with its stress state, temperature, and loading rate, therefore, the loading condition of the asphalt mixture's dynamic modulus test should be consistent with the actual temperature, loading frequency, and stress state that are applied to the mixture in actual pavement, thus can the test produce an objective result that can accurately reflect the actual stress-strain relationship for the asphalt mixture. However, due to limitations in the loading capacity of current dynamic modulus test equipment, the present modulus tester cannot yet set such a loading condition whose stress state is consistent with that of asphalt mixture in actual pavement. As a result, the modulus testing results of the current test may not accurately reflect the actual stress-strain characteristics of an asphalt mixture under real traffic loads. Therefore, this paper aims to figure out the impact of stress state on asphalt mixture’s dynamic modulus, and firstly conducts a numerical analysis to ascertain asphalt pavement’s triaxial stress state at different depth, then, utilizing the nonlinear elasticity theory of Soil Plasticity, proposes a theoretical model that can reflect triaxial stress state’s effect on asphalt mixture’s dynamic modulus, and then, arranges a series of triaxial dynamic modulus tests for asphalt mixture in different stress state to verify the model’s effectiveness, and meantime analyzes stress state’s influencing rule to asphalt mixture’s dynamic modulus. Their results indicate, the asphalt mixture of the actual pavement is in an obvious triaxial stress state, and that the higher the triaxial stress state, the larger the dynamic modulus, particularly for the mixture near the surface, whose high stress state will lead to their dynamic modulus to be significantly larger than that of the underlying course, while the model proposed in this paper can to a large extent reflect this impact.

Experimental study on multiscale strain localisation based on soil cell element model

The granular and natural characteristics of soil introduce size effects to its deformation and strength properties. Therefore, investigating the phenomenon of strain localisation in soil requires a multi-scale characterisation. This study examined the intrinsic scale patterns in samples with different sizes of reinforcing particles through triaxial compression tests. Additionally, the formation mechanism of microscopic shear bands was investigated using numerical simulation methods. Drawing from the soil cell model theory, the average strain energy release coefficient was introduced to validate the transformation of the overall strain energy of the specimen after reaching the peak stress. This reflects the progressive initiation and competitive process of multiple bands. The results indicate that samples with different sizes and types of reinforcing particles exhibit various failure patterns, including single-type, ‘x’-shaped, ‘v’-shaped, parallel and others. The soil exhibits size effects, with the ratio of intrinsic scale to particle size decreasing as the size of reinforcing particles increases. Prior to the stress peak, non-elastic dissipation energy begins to increase, indicating the initiation of plastic deformation in the soil. Localised strain zones are activated, and after the peak, there is a sharp increase in stress within the shear bands, accompanied by rebound outside the band.

Permanent deformation and particle crushability of calcareous sands under cyclic traffic-induced loadings through simple shear apparatus

This study focuses on investigating permanent deformations, encompassing normal and shear strains, of calcareous sandy soils subjected to drained cyclic traffic-induced loadings. The investigation utilizes a Simple Shear (SS) apparatus allowing for variations in both normal and shear stress components over each cycle and incorporates Principal Stress Rotation (PSR), a feature not replicable in conventional cyclic uniaxial triaxial tests which is the key aspect of this research. The study also accounts for the harmonically changing the effective horizontal stress resulting from cyclic variations of effective vertical stress, conducted under a horizontally constrained boundary condition with zero lateral strain. A series of drained cyclic simple shear experiments is carried out, implementing a heart-shaped stress path, encompassing up to 1000 cycles. The objective of the study is to analyze permanent normal and shear deformations, along with associated total particle crushing, using both sieving analyses and 2D image processing of particles. The study also evaluates the impact of an initial static shear stress originating from the longitudinal slope of roads. The findings highlight the influences of induced cyclic amplitudes of stress components, principal stress and strain rate rotation, and initial static shear stress on the development of permanent strains. Furthermore, the research characterizes particle crushability in terms of total crushability over such loading, examining its dependency on relative density and variations in both shear and normal stress components.

Constitutive behaviour of a granular matrix containing coal mine waste intermixed with rubber crumbs

AbstractTraditional railway substructure materials (i.e., natural crushed rock aggregates used for ballast and capping layers) degrade under service loads, incurring higher periodic maintenance costs compared to recycled materials. Using recycled waste materials such as coal wash and rubber crumbs for infrastructure upgrades not only reduces construction and maintenance costs but also supports environmental sustainability. By exploring unconventional avenues, earlier studies have delved into the viability of blending rubber crumbs (RC) and coal wash (CW) as an innovative substitute for traditional railway substructure materials, with a specific focus on the capping layer. This study introduces a semi-empirical constitutive model to simulate the response of mixtures of coal wash and rubber crumbs (CWRC) using the bounding surface plasticity framework. The novelty of this study is that a modified volumetric strain expression is introduced to capture the compressibility of rubber, thus enabling a more accurate representation of the internal deformation of rubber within the granular matrix. The variation of rubber content in the mixture is captured by the corresponding critical state void ratio surface and the hardening modulus. The theoretical model is then calibrated and validated using static drained triaxial test data for CWRC mixtures as well as mixtures of steel furnace slag, coal wash, and rubber crumbs (SFS + CW + RC).

Improving non-uniform gravelly sand using microbially induced carbonate precipitation: An outdoor cubic-meter scale trial by engineering contractors

Soil improvement using microbially induced carbonate precipitation (MICP) remains largely confined to the laboratory, with only a very small number of large-scale experiments having been completed under field conditions and none by engineering contractors. This study presents a cubic-meter scale improvement of heterogeneous natural sand collected from a local quarry, with a wide variation in grain size, via MICP. The MICP trial was conducted by engineering contractors in a cubic test cell under variable temperatures ranging from 5 °C to 19 °C. The upscaling of cultivation of Sporosarcina pasteurii (600 L for each treatment cycle) under non-sterile conditions, as performed by engineering contractors, achieved an optical density (OD600) of 0.89 and a specific urease activity of 2.5 mM urea/min/OD600. Post-MICP-treated sands were subjected to a series of coring, block sampling and laboratory tests. The block sampling process indicated that the majority of sand was effectively cemented, with a small region near a side wall forming a less well-cemented zone, likely induced by less effective fluid delivery in this region. The unconfined compressive strengths of three cores (diameter: 10 cm, length: 22 cm) were 3.6, 4.4, and 7.6 MPa. Consolidated-drained triaxial tests on sub-sampled cores also demonstrated rock-like material behaviour, with a peak friction angle of 43.6° and peak cohesion of 0.64 MPa, and ultimate state frictional angles of 42.0° and ultimate cohesion of 0.12 MPa. The increased shear parameters of the bio-cemented samples (relative to the untreated samples) have many implications for mitigation of geotechnical hazards such as soil liquefaction. The study marks a step forward industrial implementation of MICP for soil improvement by engineering contractors without prior knowledge of MICP.