The intervertebral discs are of the most important body tissues that provides the required flexibility for the spine during daily activities. Due to the lamellar structure of the Annulus Fibrosus, that surrounds the central part of Nucleus Pulposus, it may show anisotropic behavior in carrying the applied loads. Therefore, this aspect was investigated using the experimental data that were obtained by Confined Compression relaxation Tests on samples in three different directions: Axial, radial and circumferential. To obtain the experimental values of the permeability and aggregate modulus as material parameters, Test data in three directions were fit to the constitutive equations that were based on the biphasic relaxation model. The results for the permeability and aggregate modulus in three directions show that the material parameters are almost independent of direction and therefore, it is concluded that AF can be treated as an isotropic material under the compressive loads.

This paper presents the results of Adaptive Neuro-Fuzzy Inference System (ANFIS) based model for Reinforced circular columns strengthened with Carbon fibre reinforced polymer (CFRP) sheets. The main objective of this paper is to propose ANFIS based model for predicting the performance characteristics of CFRP strengthened RC columns and to compare it with the experimental results. ANFIS uses neural network for computing the numerical results of functions and fuzzy logic for making decisions based on the resulting values. The ANFIS predicted results show good agreement with the experimental Test results.

There are several methods to predict the Compression strength of reinforced concrete columns Confined by FRP, such as experimental methods, theory of elasticity and plasticity. Meanwhile, due to its good potential and high accuracy in predicting different problems, the soft computing techniques has attracted considerable attentions. Soft computing includes methods and programs to deal with complex computational problems. The objective of this study is to evaluate and compare the performance of four methods of Least Squares Support Vector Machine (LS-SVM), the Weight Least Squares Support Vector Machine (WLS-SVM), Adaptive Neuro-Fuzzy Inference System (ANFIS) and Particle Swarm Optimization-Adaptive Network based Fuzzy Inference System (PSO-ANFIS) for predicting the Compression strength of reinforced concrete columns Confined by FRP. A total of 95 laboratory data are selected for use in these methods. The Root Mean Square Error (RMSE) and the correlation coefficient of the results are used to validate and compare the performance of the methods. The results of the study show that the PSO-ANFIS method with the RMSE of 4. 610 and the coefficient of determination of R2 = 0. 9677 predicts Compression strength of reinforced concrete columns Confined by FRP with high accuracy and therefore, it can be a good alternative to time-consuming and costly laboratory methods.

In developing new pedotransfer functions, finding new input variables is a major challenge for improving the estimation of soil hydraulic properties. In this study, behavior of soils under compaction along with some basic soil properties were used as new inputs for the estimation of saturated hydraulic conductivity (Ks) of 120 soil samples from five provinces, namely, Mazandaran, West and East Azarbaijan, Kermanshah, and Hamadan. The Ks was estimated using Atterberg limits (liquid limit, plastic limit and shrinkage limit), Confined Compression curve parameters and basic soil properties (silt/sand, clay percentage and bulk density) as predictors, at 3 steps. At the first step, only the basic soil properties were used as predictors. Pedotransfer functions developed by regression method showed that step 2, with the inputs of Confined Compression curve parameters, and step 3, with the inputs of only Atterberg limits, both along with basic soil properties, led to relative improvement in the Ks estimates. The root mean square error (RMSE) values in training and Testing of the steps 1, 2, and 3 were 0. 624, 0. 620, 0. 584 and 0. 887, 0. 821, 0. 829, respectively. According to RMSE criterion, relative improvement values for the training of the second and third steps were 0. 64% and 6. 35% and for the Testing of the second and third steps were 7. 55% and 6. 33%, respectively. According to the R2adj entering Confined Compression curve parameters or Atterberg limits along with the basic soil properties could not improve the estimations. Accuracy of the third step (according to RMSE and Akaike’ s information criterion) and reliability of the second and third steps (according to RMSE and Akaike’ s information criterion) were improved in comparison with the first step.

This study is an attempt to investigate the mechanical behavior of proppant packs deforming under Compression loading. A generalized Confined Compression Test (CCT) was simulated in the present study to investigate the deformation of walnut/ceramic proppants against Compression. In this way, the CCT was simulated using ABAQUS explicit code. Unlike ordinary CCT, we obtained permeability of compressed packs through image processing of deformed packs. It was observed that a pack with small particles could markedly withstand deformation, however, at the expense of having lower permeability. Also, selecting a proper proppant pack strongly depends on the prevailing stress regime, where at low stress (<30 MPa) uniform walnut pack has the same permeability as a medley of walnut/ceramic pack. But, at greater stresses (> 40 Mpa), the pack with more ceramic is the best choice. Mixtures of walnut and ceramic proppants showed greatly strength improvement compared to similar cases with pure walnut granules. As a result, making use of such packing is highly recommended due to significant mechanical stability and also being of lower price compared to packs of pure ceramic granules.

For prevention of soil compaction, knowledge of allowable Compression stress limit (compaction strength) in soil is important. Pre-compaction stress ( spc ) was introduced as soil compaction strength and often used as a criterion for evaluation of soil susceptibility to compaction. In this research, pre-compaction stress was measured for a sandy loam soil with plate sinkage (PST) and Confined Compression (CCT) Tests. To prepare soil samples with different initial compactness, two soil water contents (17 and 19%db) and six pre-loading stresses (0, 25, 50, 100, 150 and 200 kPa) were used. The effects of soil water content and pre-loading stress on estimated pre-compaction stress were studied using a factorial experiment in a completely randomized design with three replications. The spc values were significantly influenced by loading combination and soil water content. For PST, pre-load increase and higher soil water content resulted in higher and lower values of spc , respectively. However, predicted spc value increased with higher soil water content for CCT. The results also showed that the spc predicted with PST was accurate, whereas the values obtained with CCT were 4.5 (at 17 %db) and 8.5 (at 19 %db) times higher than the applied pre-loads. Overall, the findings indicated that spc prediction depends on the Compression Test, and PST could be a suitable method for soil pre-compaction stress (compaction strength) determination in sustainable soil management, i.e., soil trafficability and tillage. The PST method is also suitable to assess the effect of managing factors on pre-compaction stress.

Frozen sand soils are often observed in underground urban and engineering constructions in cold climates. Artificial ground freezing is a soil improvement technique, and soils in coastal areas are mostly comprised of poorly-graded sand with low moisture and temperature. Thus, it is required to explore the effects of different factors on the strength of frozen soils in such areas. In addition, the freezing age required to obtain sufficient strength is studied. The present study investigates sand from the Shorabil Lake shore in Ardabil, Iran, frozen in cold seasons. To evaluate the effects of the soil grain size, sands with gran sizes of 0.15 and 0.25 mm mixed with clay in different ratios were employed. Uniaxial compressive Testing was implemented to measure the unConfined compressive strength of ten soil mixtures with four moisture contents. Thus, a total of 40 mixtures were studied at three freezing ages. The stress-strain curves showed strain softening. The specimens had almost the same strength at shorter freezing ages. As the freezing age increased, different stresses were observed due to the clay content; the strength of a specimen with a low clay content remained almost unchanged as the freezing age increased. The specimen with a clay content of 50% and a moisture content of 15% had a strength of 205.5 kPa at a freezing age of 24 h and 283.8 kPa at a freezing age of 72 h. Also, the specimen with a clay content of 10% and a moisture of 15% was found to have strengths of 265.4 and 283.8 kPa at the freezing ages of 24 and 72 h, respectively. Several specimens underwent an up to 36% decline in strength as the sand grain size decreased; however, the trend was still the case, and the specimen with 30% clay showed the highest strength in most cases.

The Confined Compression curve (CCC) of soil and its parameters reflect the impact of management operations such as tillage, cover crops, and intercropping on the physical and mechanical properties of the soil. No research has investigated the simultaneous effect of these three factors on the CCC. Therefore, the effects of two different tillage systems, moldboard plowing (MP, conventional tillage) and chisel plowing (CP, reduced tillage), combined with cover crop (CC) and without cover crop (NC) (i.e., planting Lathyrus sativus as/without cover crop) and three cropping systems (summer squash (Cucurbita pepo), green bean (Phaseolus vulgaris), and their intercropping) were investigated on soil compaction characteristics. Next, the CCC of the soil was measured, and its parameters were derived. In MP-CC treatment compared to MP-NC, the Compression index (0.43) decreased and pre-Compression stress increased by 19%. The low organic matter in NC-summer squash treatment reduced the swelling index (soil mechanical resilience) compared to other treatments in the ranges of 4.76-33%. Besides, MP increased the loading swelling index compared to CP by 33%. Overall, the best management was the application of the CP-CC under intercropping of summer squash with green beans because it reduced the soil compaction. Moreover, CP improved the soil’s physical-mechanical properties.