General Failure Research Articles

Retracted: Breaking Stress Criterion That Changes Everything We Know about Materials Failure

The perennial deficiencies of the failure models in the materials field have profoundly and significantly impacted all associated technical fields that depend on accurate failure predictions. The heart of this study is the presentation of a methodology that identifies a newly derived one-parameter criterion as the only general failure theory for noncompressible, homogeneous, and isotropic materials subjected to multiaxial states of stress and various boundary conditions, providing the solution to this longstanding problem. This theory is the counterpart and companion piece to the theory of elasticity and is in a formalism that is suitable for broad application. Utilizing advanced finite-element analysis, the maximum internal breaking stress corresponding to the maximum applied external force is identified as a unified and universal material failure criterion for determining the structural capacity of any system, regardless of its geometry or architecture. A comparison between the proposed criterion and methodology against design codes reveals that current provisions may underestimate the structural capacity by 2.17 times or overestimate the capacity by 2.096 times. It also shows that existing standards may underestimate the structural capacity by 1.4 times or overestimate the capacity by 2.49 times. The proposed failure criterion and methodology will pave the way for a new era in designing unconventional structural systems composed of unconventional materials.

An evaluation on large language model outputs: Discourse and memorization

We present an empirical evaluation of various outputs generated by nine of the most widely-available large language models (LLMs). Our analysis is done with off-the-shelf, readily-available tools. We find a correlation between percentage of memorized text, percentage of unique text, and overall output quality, when measured with respect to output pathologies such as counterfactual and logically-flawed statements, and general failures like not staying on topic. Overall, 80.0% of the outputs evaluated contained memorized data, but outputs containing the most memorized content were also more likely to be considered of high quality. We discuss and evaluate mitigation strategies, showing that, in the models evaluated, the rate of memorized text being output is reduced.

Early Endpoints in High-risk Localized Prostate Cancer: Exploratory Analysis of Three Radiation Therapy Oncology Group Phase 3 Studies

BackgroundEarly endpoints in clinical trials of high-risk localized prostate cancer (HRLPC) that resemble those monitored in real-world practice could expedite clinical development. ObjectiveTo assess the association of prostate-specific antigen (PSA) recurrence (PSA-R)-based early endpoints with metastasis-free survival (MFS), overall survival (OS), and prostate cancer (PC)-specific survival (PCSS), and to identify clinically undetectable disease. Design, setting, and participantsA post hoc analysis of patients with HRLPC from Radiation Therapy Oncology Group studies 9202, 9902, and 0521 was performed. InterventionLong-term adjuvant androgen-deprivation therapy (ADT) and post-primary definitive radiotherapy. Outcome measurements and statistical analysisEvent-free survival (EFS; PSA-R, locoregional recurrence [LRR], distant metastasis [DM], or death), biochemical failure (PSA-R), general clinical failure (PSA-R, LRR, DM, ADT initiation, or death), and no evidence of disease (NED; alive patients without PSA-R, LRR, DM, and subsequent PC therapy, and with testosterone recovery) were assessed for association with MFS, OS, and PCSS using correlation and landmark analyses, Kaplan-Meier method, and Cox proportional-hazard model. PSA-R was defined as PSA nadir + 2 ng/ml; PSA nadir + 2 ng/ml and rising; PSA >5, 10, and 25 ng/ml; or PSA doubling time (PSADT) <6 mo. Results and limitationsAmong assessed early endpoints, EFS with PSA nadir + 2 ng/ml and rising, or with PSA >5 ng/ml was associated with MFS, OS, and PCSS. No development of EFS with PSADT <6 mo or ADT initiation event or achievement of NED at 3 yr was associated with prolonged OS, MFS, and PCSS (hazard ratio [95% confidence interval], 0.53 [0.45–0.64], 0.63 [0.52–0.76], and 0.26 [0.18–0.36], or 0.56 [0.48–0.66], 0.62 [0.52–0.74], and 0.26 [0.19–0.37]) after the landmark time. Older studies performed before the current guidance should be interpreted with caution. ConclusionsWe identified EFS with PSA nadir + 2 ng/ml and rising, PSA >5 ng/ml, or PSADT <6 mo ± ADT initiation and NED as potentially promising early endpoints in HRLPC that should be validated further. Patient summaryWe identified novel clinical measures that may expedite the development of new medicines for patients with localized prostate cancer at a high risk of progression. These measures, which took into account prostate-specific antigen assessments and other clinical characteristics, should be confirmed in future studies. We also defined a novel measure of no evidence of disease that can help treating physicians identify patients with clinically undetectable disease.

Developing failure criteria for laceration injury of dermal tissue

Despite its importance, there is a poor understanding of human injury tolerance to trauma generally, and more specifically understanding of the mechanics of skin penetration or laceration. The objective of this analysis is to determine the failure criteria that will allow the evaluation of the laceration risk of blunt-tipped edges within a computational modeling environment. An axisymmetric tissue finite element model was set up in Abaqus 2021 to match the experimental set-up from a previous study. The model simulated the pressing of penetrometer geometries into dermal tissue, and stress and strain outputs were evaluated at the experimental failure force. Two separate nonlinear hyperelastic material models were calibrated for the dermis to data from the literature (high and low stiffness models). For both the high-stiffness and low-stiffness skin models, the failure force appears to occur near a local maximum in the principal strain. All failures occurred after the maximum strain near or at the top surface is or above 59%, with mid-thickness strain at a similar level. The strain energy density is concentrated near the edge tip for each configuration, indicating highly localized material damage at the point of loading, and increases rapidly prior to the approximate failure force. As the edge is further compressed into the tissue, the stress triaxiality near the edge contacting point decreases towards zero. This study has identified general failure criteria for skin laceration which can be implemented in a computational model. A higher risk for laceration would be indicated with strain energy density larger than 60 mJ/mm3, dermal strain larger than 55%, and stress triaxiality below 0.1. These findings were largely insensitive to the dermal stiffness and broadly applicable across different indenter geometries. It is expected that this framework may be implemented to evaluate hazardous forces for product edges, interactions with robots, and interfaces with medical and drug delivery devices.

Transition from rock mass creep to progressive failure for rockslide initiation at Mt. Conero (Italy)

The full description of rock mass behaviour involved in slope deformation, through its onset and progression until ultimate failure, is still a challenge in numerical simulations. The slope deformation that involved the coastal sector of Mt. Conero (Italy), leading to the rock avalanche of Portonovo, is an impressive example of a multistage creep evolution involving a jointed rock mass towards general failure. A landslide mass for the last event up to 5 Mm3 has previously been estimated from geomorphological analysis. This volume is not consistent with the size of the scar or the landslide deposit, suggesting a history of failures. Moreover, field evidence of pre-failure strain suggests progressive failure of the slope leading up to failure. In this study, a numerical back-analysis was set up using the finite difference method in a stress–strain approach, which applied an uncoupled solution to simulate the creep process and the progressive failure of the slope, as well as the accumulation of damage. The modelling outputs support the hypothesis that the landslide event was marked by two distinct episodes, each with volumes of approximately 20 Mm3, at 56 and 16 ka, which is consistent with the relative dating constraints. Additionally, a numerical back-analysis of the rock mass viscosity was calibrated and validated on the size of the scar area of the Portonovo landslide and on the morphological and structural evidence. The adopted strain-softening models caused significant differences in strain distribution and slope failure evolution. The proposed modelling demonstrated the importance of the creep process in controlling slope evolution and the reliability of the tested analytical approach for the analysis of progressive brittle rock failure, including the three-stage evolution of time-dependent viscous processes.

A General Self-Adaptive DC Current Control of LCC-HVDC for Eliminating Subsequent Commutation Failure

With more renewable resources are integrated into the receiving-end AC grid through the LCC-HVDC link, a single-infeed LCC-HVDC (SIDC) system is facing a critical subsequent commutation failure (SCF), which stems from the poor dynamic reactive power support capability of the existing LCC-HVDC link's control strategies. This letter proposes a general self-adaptive DC current control (GSDC <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) of LCC-HVDC to eliminate the SCF, based on the dynamic reactive power interaction mechanism. Then, multiple comparative studies with the existing control strategies are implemented to verify the validation of the proposed control strategy by PSCAD/EMTDC <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TM</sup> . A fast evaluation index, called general commutation failure immunity index (GCFII), is also defined to show the performance of the proposed control strategy in eliminating the SCF.

0944 Telemedicine (TM) to provide outpatient care for sleep disorders in complex neurological patients in an academic Medical Center

Abstract Introduction Since the widespread adoption of telemedicine (TM) as a reimbursable option for the delivery of healthcare, (particularly clinic visits), the field of sleep medicine has been a beneficiary. In complex neurological patients, it was hypothesized that physical and cognitive constraints would limit the use of TM. This analysis was undertaken to evaluate patient care strategies in an academic neurology department based in a large metropolitan city Methods 2964 adult patients who opted for neurology clinic visits via video TM in the last 6 months were included from electronic medical record review at the University of Texas Health Sciences Center in Houston. Of these, 557 were seen in sleep medicine specialty. A successful visit was defined as a simultaneous connection of at least 2 parties for a minimum duration of time defined by institutional guidelines. Patients were analyzed in age subgroups (&amp;lt; 30, 31-50, 51-70 and &amp;gt;70 years of age) as well as race (Asian, Black, Hispanic, White and Others). Neurological diagnoses in these patients included stroke, epilepsy, movement disorders, cognitive disorders, neuromuscular conditions and less commonly multiple sclerosis Results Sleep medicine providers comprise of 2/53 (3.7%) of the department’s clinical providers, but accounted for 18.7% of TM visits. 97% (182/186) of new patients and 95% (354/371) of established patients had successful TM visits. Among general neurology patients, these numbers were 89% and 88% respectively. There was a statistically significant difference between successful visits in the sleep medicine and overall neurology patient groups (p value 0.0003 for new, 0.0001 for established patients). Among sleep medicine patients, percentage failures were 2.9, 3.3, 4.1 and 3.9 among the respective age groups. Percentage failures across the respective racial groups were 0, 6.1, 4.8, 4.2 and 1.9. Reasons cited for unsuccessful visits included camera, microphone and general hardware failures. Surprisingly network failure was not reported Conclusion The success of telemedicine clinic visits for the management of sleep disorders is not impacted by physical and cognitive impairment in patients with complex neurological conditions. Further analysis to include success of sleep diagnostics and treatment of sleep disorders (start-to-finish pathway), via telemedicine in this complex population is underway Support (if any) None

Choosing the Best Design in Surgical Research.

Choosing the Best Design in Surgical Research.

Response of UPVC pipes buried in sand under lateral ground movement

As a key part of global lifeline infrastructure, buried pipelines play a vital role in transporting products for the daily life of human beings. However, the ultimate soil resistance and yield displacement are only derived for rigid pipes in current design guidelines, which are difficult to guide the analysis of flexible pipes. This investigation presents large-scale laboratory tests on flexible UPVC pipes subjected to lateral ground movements. The soil failure mechanism and pipe deformation were tracked. The reaction developing on UPVC pipe was measured as a function of pipe lateral displacement, embedment depth, sand bed density and pipe wall thickness. Analysis results reveal that the failure mode of soil changed from the general shear failure to the local shear failure, in which the soil arching effect occurred in both the active and passive loading areas, as the embedment ratio increased. Current design approaches could overestimate or underestimate the ultimate soil resistance of UPVC pipe heavily under various conditions, while the measured yield displacement was 2 to 3 times the prediction from the design guidelines. Finally, a simplified design method was proposed based on the pipe yield displacement for predicting the maximum longitudinal strain of UPVC pipes under lateral loading.

Detonation of high explosives containing phosphorus(V) nitride, P3N5

AbstractComposition A4 (RDX/wax, 94/6 wt %) modified with additional phosphorus(V) nitride, P3N5 (CAS‐No.: [12136‐91‐3]) and aluminum does not show increased detonation velocity, Gurney energy or blast pressure when compared with the baseline formulation. The general failure of P3N5 to contribute to the detonation performance is understood to result from the low negative enthalpy of formation of P3N5 that makes this compound a “heat sink” in the detonation and post detonation zone. A formulation containing both P3N5 and Al (RDX/P3N5/Al/wax: 50.76/36/10/3.24 wt %) shows superior luminosity and temperature of the post detonation fireball when compared with both Comp A4 and even aluminized Comp A4 (Hexal=RDX/Al/wax: 65.8/30/4.2 wt %). The superior luminosity is understood to be due to formation of aluminum phosphate, AlPO4 a material with high optical emissivity which however, decomposes above T=1600 °C.

Relationship between Cognitive Failure and Internet Addiction of Higher Secondary Students of Purulia District of West Bengal: A Study

In the 21st-century internet, addiction has become a common phenomenon among students. Internet addiction is sometimes referred to as internet addiction disorder, pathological internet usage, internet reliance, problematic internet use, overuse and compulsive internet use. And cognitive failure is outlined as the probable consequence of a general failure of the cognitive and control system. The present study has aimed to determine the relationship between cognitive failure and internet addiction of higher secondary students of the Purulia district of West Bengal. For the present study, the researchers have used descriptive survey-type research. The data for the present study has been collected from seventy-eight (78) class XI students from randomly selected two schools in the Purulia district of West Bengal, India, using a simple random sampling technique. The researchers have used appropriate descriptive statistics like mean, standard deviation, correlation and inferential statistics like the Shapiro-Wilk test for normality test, ‘t-test and Mann-Whitney U test for data analysis. The result revealed a significant relationship between cognitive failure and internet addiction among higher secondary Purulia district of West Bengal students. However, no significant difference has been observed in cognitive failure and internet addiction regarding gender, location and stream.

A discrete element analysis for general failure behavior of basalt

Discrete element method is a commonly used numerical method in rock mechanics and rock engineering. In this research, the flat-joint contact bond model is used to reproduce the macro-properties of basalt on an assembly of particles. A series of laboratory tests, including uniaxial compression test, Brazilian tension test, and fracture toughness test are used to simulate progressive degradation of rock mass strength in a size-independent model with a unique set of micro-properties. The work involves a detailed analysis for estimating compressive elastic modulus, Poisson's ratio, bimodularity, mode I fracture toughness, crack closure, crack initiation, and crack damage thresholds, as well as the tensile and compressive strengths. The constructed flat-jointed material yields a realistic uniaxial compression to tensile strength ratio and nonlinear stress-strain response through sustaining adequate particle interlocking and embedded pre-existing microcracks. The role of sample size on the compressive elastic modulus, crack initiation and crack damage stress limits is demonstrated in detail. A model size-independency analysis was also performed to examine the effect of particle size on the results. The numerical results presented in this study are within 10% of the laboratory results.

Seismic behavior and theoretical analysis of mortise–tenon joints reinforced with steel components

Wood structures have been vigorously popularized and developed because they have low carbon emissions and acceptable earthquake resistance. To solve the general pull-out failure of mortise–tenon joints (MTJs) under earthquake loads, reinforcement techniques, such as steel strip plate (SSP), hollow rectangular steel plate (HRSP), U-shape steel plate (USP), and T-shape steel plate (TSP) methods, have been proposed. Low cyclic loading tests were conducted on five joints to investigate the effect of reinforcement methods on the seismic behavior of MTJs. Furthermore, the peak bearing capacity of reinforced MTJs was theoretically analyzed based on European, American, and Chinese specifications; the calculations were compared with the test results. To verify the accuracy of the theoretical analysis, ABAQUS software, a finite element simulation application, was used. The test results show that the failure modes of joints with or without reinforcements are tenon pull-out, self-tapping screw pull-out, and shear failure. Moreover, the USP-reinforced MTJ exhibited the best seismic performance, followed by the MTJs reinforced with TSP, HRSP, and SSP. The theoretical calculation and test results are in good agreement. The simulation results indicate that the proposed calculation methods can accurately predict the peak bearing capacity of steel-reinforced MTJs.

HSPB8 frameshift mutant aggregates weaken chaperone-assisted selective autophagy in neuromyopathies

ABSTRACT Chaperone-assisted selective autophagy (CASA) is a highly selective pathway for the disposal of misfolding and aggregating proteins. In muscle, CASA assures muscle integrity by favoring the turnover of structural components damaged by mechanical strain. In neurons, CASA promotes the removal of aggregating substrates. A crucial player of CASA is HSPB8 (heat shock protein family B (small) member 8), which acts in a complex with HSPA, their cochaperone BAG3, and the E3 ubiquitin ligase STUB1. Recently, four novel HSPB8 frameshift (fs) gene mutations have been linked to neuromyopathies, and encode carboxy-terminally mutated HSPB8, sharing a common C-terminal extension. Here, we analyzed the biochemical and functional alterations associated with the HSPB8_fs mutant proteins. We demonstrated that HSPB8_fs mutants are highly insoluble and tend to form proteinaceous aggregates in the cytoplasm. Notably, all HSPB8 frameshift mutants retain their ability to interact with CASA members but sequester them into the HSPB8-positive aggregates together with two autophagy receptors SQSTM1/p62 and TAX1BP1. This copartitioning process negatively affects the CASA capability to remove its clients and causes a general failure in proteostasis response. Further analyses revealed that the aggregation of the HSPB8_fs mutants occurs independently of the other CASA members or from the autophagy receptors interaction, but it is an intrinsic feature of the mutated amino acid sequence. HSPB8_fs mutants aggregation alters the differentiation capacity of muscle cells and impairs sarcomere organization. Collectively, these results shed light on a potential pathogenic mechanism shared by the HSPB8_fs mutants described in neuromuscular diseases. Abbreviations: ACD: α-crystallin domain; ACTN: actinin alpha; BAG3: BAG cochaperone 3; C: carboxy; CASA: chaperone-assisted selective autophagy; CE: carboxy-terminal extension; CLEM: correlative light and electron microscopy; CMT2L: Charcot-Marie-Tooth type 2L; CTR: carboxy-terminal region; dHMNII: distal hereditary motor neuropathy type II; EV: empty vector; FRA: filter retardation assay; fs: frameshift; HSPA/HSP70: heat shock protein family A (Hsp70); HSPB1/Hsp27: heat shock protein family B (small) member 1; HSPB8/Hsp22: heat shock protein family B (small) member 8; HTT: huntingtin; KO: knockout; MAP1LC3B/LC3: microtubule associated protein 1 light chain 3 beta; MD: molecular dynamics; MTOC: microtubule organizing center; MYH: myosin heavy chain; MYOG: myogenin; NBR1: NBR1 autophagy cargo receptor; CALCOCO2/NDP52: calcium binding and coiled-coil domain 2; NSC34: Neuroblastoma X Spinal Cord 34; OPTN: optineurin; polyQ: polyglutamine; SQSTM1/p62: sequestosome 1; STUB1/CHIP: STIP1 homology and U-box containing protein 1; TARDBP/TDP-43: TAR DNA binding protein; TAX1BP1: Tax1 binding protein 1; TUBA: tubulin alpha; WT: wild-type.

Sentinel Lymph Node Biopsy in Breast Cancer Patients Undergoing Neo-Adjuvant Chemotherapy: Clinical Experience with Node-Negative and Node-Positive Disease Prior to Systemic Therapy

Sentinel lymph node biopsy (SLNB) has emerged as the standard procedure to replace axillary lymph node dissection (ALND) in breast cancer (BC) patients undergoing neo-adjuvant chemotherapy (NAC). SLNB is accepted in clinically node-negative (cN0) patients; however, its role in clinically node-positive (cN+) patients is debatable. We performed a retrospective analysis of BC patients undergoing NAC and SLNB. Our aim was to evaluate the clinical significance of SLNB in the setting of NAC. This was accomplished by comparing the characteristics and oncological outcomes between cN0 and cN+ patients prior to NAC and type of axillary surgery. A total of 291 patients were included in the analysis: 131 were cN0 and 160 were cN+ who became ycN0 after NAC. At a median follow-up of 43 months, axillary recurrence occurred in three cN0 (2.3%) and two cN+ (1.3%) patients. However, there were no statistically significant differences in oncological outcomes (disease-free survival, distant disease-free survival, overall survival, and breast-cancer-specific survival) between cN0 and cN+ patients nor between patients treated with SLNB only or ALND. SLNB in the setting of NAC is an acceptable procedure with a general good prognosis and low axillary failure rates for both cN0 and cN+ patients.

Structural Damage Evolution of Mesoscale Representative Elementary Areas of Mudstones

The mechanical behavior of mudstones is significantly affected by their mesostructure. This study investigates the damage evolution of red mudstone mesostructures under uniaxial compression through U-Net image segmentation, mesoscopic representative elementary area (mREA), meso-element equivalent method, and linearly superimposed model. Results show that the mREAs can be simplified as a binary structure comprising nonclayey minerals and a porous matrix. The inclusion-matrix interfaces constituted by the dominant inclusions, such as large inclusions and a series of inclusions with specific arrangements, are the weakest regions at the postpeak stage. The shear failure of these interfaces leads to general shear failure with a penetrating principal fracture or local shear with several nonpenetrating local fractures in the mREAs. The damage evolution and failure mode are sensitive to the inclusion geometric features, e.g., inclination, grain size, and spacing. However, the uniaxial compressive strength (UCS) is mainly determined by the included angle between the dominant inclusion inclination and the loading direction. With consistent composition, an increase in the included angle from 0 to 90° results in an increase in the UCS of the muddy facies and a decrease in the sandy facies, with the UCS of the sandy facies being more sensitive to changes in the included angle. Our findings indicate that the structural failure of red mudstones from mesoscopic to macroscopic is driven by the accumulation and expansion of shear failure at multiple scales due to the presence of hard–soft interfaces. This study enhances our understanding of the structural failure mechanism of mudstones and serves as a practical reference for the mesomechanical testing of clay rocks.

Does anterior plus posterior interosseus neurectomy lead to better outcomes than isolated posterior interosseus denervation in the treatment of chronic wrist pain? A systematic review of the literature and meta-analysis.

Partial wrist denervation can be performed by isolated posterior interosseous nerve (PIN) or combined PIN plus (+) anterior interosseous nerve (AIN) neurectomy procedures. The purpose of the current systematic review is to investigate any differences in clinical outcomes and failures in patients undergoing AIN + PIN vs isolated PIN neurectomy. A review of the English Literature was performed on Medline, WOS and Scopus according to PRISMA protocol combining 'wrist denervation', 'PIN neurectomy', 'AIN neurectomy', anterior interosseous nerve neurectomy' and 'posterior interosseous nerve neurectomy'. Studies were assessed with a modified Coleman Methodology Score (CMS). The primary outcome for meta-analysis was 'Failures', including all patients who have required a second surgery or those who are left with pain (defined as 'bad'). Overall, 10 studies totalling 347 wrists were included in this systematic review, with a 'moderate' CMS. The isolated PIN neurectomy technique showed a 15.1% pooled failure rate at a median follow-up of 22 months, while the combined AIN+PIN denervation had a pooled failure rate of 23.6% at a follow-up with a median of 29 months. The combined analysis of both procedures did not show significantly better results in favour of either technique, with a general failure rate of 21.6% (P = 0.0501). Partial denervation for chronic wrist pain is a salvage procedure that leads to an overall success of 78.4% for pain relief, with no substantial complications. Apparently, performing the neurectomy also of the AIN does not offer greater advantages compared to the isolated PIN neurectomy.

Resisting Nonperformativity: Emma Sulkowicz’s Challenges to Victimhood

On May 19, 2015, Columbia University President Lee Bollinger stood on stage and shook the hands of all the students whose degrees were conferred that day…all except one. This student, Emma Sulkowicz (they/them/she/hers), carried a dorm-issue mattress onto the dais—the same type of mattress on which they were raped. Sulkowicz, a gender-fluid performance artist, created the endurance performance Mattress Performance (Carry That Weight) to work against the nonperformative sexual assault process at Columbia. For one academic year, they bore the mattress everywhere on campus, reminding those around them not only of their own rape but of the university’s general failure to properly adjudicate sexual assault cases. When critics took to the internet to cast aspersions on Sulkowicz’s motives, accusing them of not being raped, Sulkowicz refused to be disciplined, filming a re-staging of their rape and posting it online. This article explores how Sulkowicz’s performances with and beyond the mattress inhabit victimhood and destroy it. By countering nonperformativity with performance, Sulkowicz transfers agency from perpetrator to survivor.

A quasi-2D exploration of optimum design settings for geotextile-reinforced sand in assistance with PIV analysis of failure mechanism

Many earlier studies were focused on testing different types of geosynthetics to investigate effect of reinforcement on bearing capacity, but the effect of tensile strength on the failure mechanism has not been examined sufficiently. Within this scope, a test setup was prepared to apply strip loads on densely compacted reinforced sand under the plane strain condition. The tank containing the reinforced sand was a rectangular prism with perfect transparency, and its interior dimensions were 960 × 200 × 650 mm3. Firstly, optimum values of design variables (depth of first sheet, length and number of sheets, space between sheets, tensile strength of sheets) for the woven geotextile reinforced sand were determined experimentally. Then, the failure mechanisms of the soil, which were reinforced with geotextiles of different tensile strengths, were observed and analyzed with particle image velocimetry (PIV) technique. Consequently, the failure mechanism of the sand with a single geotextile reinforcement was similar to general shear failure of unreinforced soil. Contrarily, the failure surfaces were deeper and longer. Additionally, the deep-footing mechanism reached out large depth in the case of four reinforcement layers. The failure mechanism converted into a punching type due to a hypothetic increase in the bearing depth of reinforcement.

Two-dimensional study of the inclusions of skirt sand and deep cement piles to improve the load‒displacement behavior of circular foundations on soft clay soil

The bearing capacity of clayey soils is low, and the induced settlements play an important role in estimating the stability of structures built on these weak soils. Therefore, these clayey soils need improved mechanical strength. In this study, a two-dimensional finite element model was used to improve the bearing capacity and settlement of soft clay soil by employing skirt sand piles, and the results were compared with reinforced cement piles. Skirt sand piles consisting of thick sand cores and closed tubes placed under a circular shallow foundation with a steel plate of suitable dimensions, as well as reinforced cement piles of different lengths and in nondrained situations were studied. These calculations were carried out using PLAXIS 2D software, and a series of finite element analyses were performed. The Mohr‒Coulomb and hardening soil models were used to model the fine-grained and granular soils, respectively. A linear elastic model was used to simulate the circular plate and skirt components. Previous experimental studies were used to validate the numerical model. The experimental test and the 2D axisymmetric model agree well. According to the assumptions, the efficiency of skirt sand piles is superior to that of deep cement piles. In addition, increasing the length of SSP skirt sand piles has a significantly greater effect on improving the bearing capacity than increasing the length of deep cement piles. As a consequence, the failure modes of piles with skirt sand were determined. It was found that the failure mode when skirt sand piles were tied into clayey soils occurred in the underlying sandy soil layer as a general shear failure.