Prediction of load-displacement performance of grouted anchors in weathered granites using FastICA-MARS as a novel model

With the rising needs of better prediction of the load-displacement performance of grouted anchors in an era of developing large-scale underground infrastructures,the existing methods in literature lack an accurate analytical model for the real-life projects or rigorous understanding of the parameters such as grouting pressures.This paper proposes Fast ICA-MARS as a novel data-driven approach for the prediction of the load-displacement performance of uplift-resisting grouted anchors.The hybrid and data-driven Fast ICA-MARS approach integrates the multivariate adaptive regression splines(MARS)technique with the Fast ICA algorithm which is for Independent Component Analysis(ICA).A database of 4315 observations for 479 different anchors from 7 different projects is established.The database is then used to train,validate and compare the Fast ICA-MARS approach with the classical MARS approach.The developed Fast ICA-MARS model can provide more accurate predictions than MARS.Moreover,the developed Fast ICA-MARS model is easy to interpret since the evaluation of the parameter importance of the independent components can be conducted along with the considerations of the correlations with the original variables.It is noteworthy to point out that the grouting pressures play a central role in the proposed model,which is considered of paramount importance in engineering practices but has not been properly taken into account in any prior analytical or empirical predictive models for the load-displacement relationships.

Quantification of ventilation enhancement using the Eye CAN roof support

Convergence of roof and floor in underground mine openings is a common occurrence. This convergence not only adversely affects the ability of workers, equipment and supplies to travel through the mine, it also reduces the effectiveness of the mine ventilation system, which is essential for the dilution of methane gas and airborne respirable dust. While installing secondary standing supports to control floor and roof convergence, such supports, by nature, partially obstruct a portion of the airway. These added obstructions inhibit the ability of the ventilation system to operate as efficiently as it could by increasing the resistance in and reducing the cross-sectional area of the airway. This study introduces and demonstrates the benefits of The Eye CAN^(TM) standing roof support, which controls floor and roof convergence and is less obstructive to air flow than conventional wooden cribs. Laboratory findings show that the normal resistance of a supported lined airway is reduced by using this new product from Burrell Mining Products, Inc., while providing the same roof support characteristics of an established product—The CANò. Load vs. displacement curves generated from laboratory tests demonstrated that this new product behaves with the same roof support characteristics as others in The CAN product family. Ventilation data gathered from a simulated mine entry was then used for computational fluid dynamics(CFD) modeling.The CFD analysis showed an improvement with The Eye CAN vs. other accepted forms of standing roof support. This proof-of-concept study suggests that, when using this new product made by Burrell Mining Products, Inc., not only will the convergence from the roof and floor be controlled, but airway resistance will also be reduced.

Semi-Deep Skirted Foundations and Numerical Solution to Evaluate Bearing Capacity

Semi-deep foundations are a remarkable solution in conditions where the soil beneath the foundation is loose to a great depth and there is no possible way to use any way of soil improvement and applying piles would not be a logical way considering their cost and time of enforcing. Skirted foundations are a type of semi-deep foundations that can penetrate to the soil up to two times of their breadth. Estimating bearing capacity of these foundations is a long geotechnical problem for engineers whether under absolute or combined loading because of their usage in offshore and onshore projects. For estimating the vertical bearing capacity of these foundations, series of finite element analyses were performed for a range of embedment ratios to investigate the effect of the length of the skirt. The foundation has been modelled with two different types of soil and the results validated with previous analytical, numerical and experimental researches. In addition, the bearing capacity of a skirted foundation under combined loading in V-H space has been analyzed by this approach and the 2-dimentional failure envelope has been presented.

A destructive field study on the behavior of piles under tension and compression

This paper involves a series of destructive full-scale load tests on long bored piles instrumented with strain gauges along the shafts,including two compression and two tension loading tests.The load-displacement response,axial force,skin friction,and the thresholds of the slip displacement for fully mobilizing the skin resistances in different soils are discussed.Moreover,the theoretical solution for estimating the pile tip settlement under compression was adopted to analyze the test results.It was found that the measured skin frictions for the piles under compression were about 6% to 42% higher than the estimated values of the cone penetration tests(CPTs),whereas the measured skin frictions in the uplift cases were about 16% to 50% smaller than the estimated values.In addition,the average limited skin frictions for the tension piles were about 0.36 to 0.78 times the average ultimate skin frictions for the piles under compression.It also can be indicated that the skin friction along the pile depth approached the limited state,and decreased from a peak value with increasing loads.

A closed-form nonlinear model for spatial Timoshenko beam flexure hinge with circular cross-section

Beam flexure hinges can achieve accurate motion and force control through the elastic deformation. This paper presents a nonlinear model for uniform and circular cross-section spatial beam flexure hinges which are commonly employed in compliant parallel mechanisms. The proposed beam model takes shear deformations into consideration and hence is applicable to both slender and thick beam flexure hinges. Starting from the first principles, the nonlinear strain measure is derived using beam kinematics and expressed in terms of translational displacements and rotational angles. Second-order approximation is employed in order to make the nonlinear strain within acceptable accuracy. The natural boundary conditions and nonlinear governing equations are derived in terms of rotational Euler angles and subsequently solved for combined end loads. The resulting end load-displacement model, which is compact and closed-form, is proved to be accurate for both slender and thick beam flexure using nonlinear finite element analysis. This beam model can provide designers with more design insight of the spatial beam flexure and thus will benefit the structural design and optimization of compliant manipulators.