Shear Strength Parameters Of Sand Research Articles

Laboratory assessment of shear strength parameters of sand amended via subsequent biopolymer-based soil treatment and enzyme-induced calcite precipitation combinations

Current ground improvement practices predominantly rely on cement; however, interest in strengthening the ground in an environmentally sustainable manner is growing due to concerns regarding the environmental impact, such as the high CO2 footprint associated with cement usage. Biopolymer-based soil treatment (BPST) and enzyme-induced calcite precipitation (EICP) have emerged as promising methods for environmentally friendly ground improvement. While several studies have demonstrated the effectiveness of BPST and EICP individually, both methods have their limitations, which can be seen as complementary (for instance, EICP is more effective for coarse soils, whereas BPST is more effective for clayey soils). Recently, efforts have been made to combine BPST with EICP to address these limitations. This study considered four consecutive BPST-EICP combinations: 1) EICP alone, 2) BPST alone, 3) pre-EICP followed by post-BPST, and 4) pre-BPST followed by post-EICP. Laboratory experiments were conducted to assess the shear strength parameters (i.e., direct shear cohesion and friction angle) of sand treated using these four methods. The peak and residual shear strength parameters of the pre-EICP followed by post-BPST soil were the highest among all cases. However, each combination is suited to specific site conditions, such as soil type, groundwater conditions, and the purpose of ground improvement.

Study on the mechanical characteristics of sand pebble surrounding rock considering the disturbance effect of tunnel excavation

When conducting tunnel construction in sandy gravel strata, disturbance to the sandy gravel soil is inevitable, resulting in alterations to the properties of the surrounding rock. This paper investigates the relationship between the relative density (Dr) and shear strength parameters under different disturbance states through the implementation of indoor triaxial tests. Utilizing Dr as a disturbance parameter, a unified disturbance function that reflects the weakening and strengthening of sandy gravel soil is proposed. Furthermore, a revised constitutive model based on this unified disturbance function is established for the first time. The study results indicated that the results calculated by traditional models, which do not take into account disturbance effects, deviate from the experimental results by more than 20%. However, the error rate of the results computed by the modified model can be reduced to within 8%. The new model establishes a dynamic relationship between relative compactness and shear strength parameters of sand and pebble soils, which can take into account both the effects of negative and positive perturbations. The results can more accurately characterise the strength and deformation properties of the surrounding rock under the influence of construction disturbances in sand and pebble ground tunnels.

Shear Strength Parameters of Sand Reinforced with Polypropylene Fiber

Shear Strength Parameters of Sand Reinforced with Polypropylene Fiber

Prediction of shear strength parameters of hydrocarbon contaminated sand based on machine learning methods

ABSTRACT The objective of this paper is to predict the effect of hydrocarbon contamination on the shear strength parameters of sand by using various machine learning platforms. Multilayer perceptron, support vector machine, random forest, gradient boosting method, and multi-output support vector machine were methods used to predict the hydrocarbon contamination impacts on the internal friction angle and cohesion of contaminated sand. Random forest exhibited the best results for cohesion, whereas, for the friction angle, the gradient boosting method outperformed other approaches. Moreover, the multi-output support vector machine yielded better results than those pertaining to a single support vector machine. Based on the sensitivity analyses, the most influencing parameter for cohesion prediction was the percentage of contamination for all the methods except for random forest where initial cohesion proved to be the primary governing factor, while the least influencing parameter was specific gravity for all methods. For the internal friction angle, the most influencing parameter was the initial friction angle for all methods except for gradient boosting where the percentage of contamination proved to be most controlling, whereas the least influencing factor was also specific gravity for all methods except for random forest where the initial cohesion was the least influencing parameter.

Effects of granulated waste glass and micro steel fiber on shear strength parameters of sand

During the construction of the various structures, soil strength plays a vital role in structural performance. Hence, soil improvement techniques are needed to improve soil strength as well. This study aimed to improve shear strength of sandy soil using Granulated waste glass (GWG) and Micro steel fiber (MSF). In order to apply this idea, there have been taken two kinds of sandy soil such as fine sand (locally available in Kushtia) and coarse sand (locally available in Domar). As for basic properties of sand, fineness modulus, specific gravity, maximum dry density, etc. are determined from experimental results. After grounding the waste glasses into granulated form and cutting the 0.70 mm steel wire into a uniform size of 10 mm in length, the GWG and MSF have been mixed in the sand by various proportions namely 5%, 10% and 15% by weight. The observation on the soil improvement technique which is adopted in this paper is summarized that the cohesion of the Kushtia sand is increased up to 1376.7% for 10% MSF and angle of internal friction is increased up to 8.7% for 10% GWG. The cohesion of the Domar sand is increased up to 1877.5% for 10% MSF and angle of internal friction is increased up to 24.4% for 15% MSF. Therefore, it can be concluded that the shear strength becomes increase for both sand up to optimum content using the considered percentage of GWG and/or MSF.

Experimental study of bearing capacity of strip footing on sand slope reinforced with tire chips

Tire chips and tire chips-soil mixtures can be used as alternative fill material in many civil engineering applications. In this study, the potential benefits of using tire chips as lightweight material to improve the bearing capacity and the settlement behavior of sand slope was investigated experimentally. For this aim, a series of direct shear and model loading tests were conducted. In direct shear tests, the effect of contents of the tire chips on the shear strength parameters of sand was investigated. Different mixing ratios of 0, 5, 10, 15 and 20% by volume were used and the optimum mixing ratio was obtained. Then, laboratory model tests were performed on a model strip footing on sand slope reinforced with randomly distributed tire chips. The loading tests were carried out on sand slope with relative density of 65% and the slope angle of <TEX>$30^{\circ}C$</TEX>. In the loading tests the percentage of tire chips to sand was taken as same as in direct shear tests. The results indicated that at the same loading level the settlement of strip footing on sand-tire chips mixture was about 30% less than in the case of pure sand. Addition of tire chips to sand increases BCR (bearing capacity ratio) from 1.17 to 1.88 with respect to tire chips content. The maximum BCR is attained at tire chips content of 10%.

Comparison of sandy soil shear strength parameters obtained by various construction direct shear apparatuses

An analysis of test results performed by common type of direct shear apparatuses shows that normal stress on the shear plane of soil sample is not equal to vertical component of distributed external load applied to the top of soil sample. Performed measurements cleared that only 65–85% of total vertical load is transmitted to the sample shear plane. Thus, determining of the soil shear strength depends on shear apparatus construction, i.e. on actual magnitude of vertical load transmitted to the shear plane. The paper presents an analysis of shear strength parameters of sand determined by two different construction of direct shear apparatuses with movable lower shear ring. The soil shear strength parameters by employing direct shear apparatus SPF-2 have been obtained under constant vertical load and measuring the vertical load at different positions, namely: at the bottom and that of at the top of soil sample, respectively. The soil strength parameters by employing the universal shear testing device ADS 1/3 were determined under two conditions, namely: by maintaining constant soil volume and that of for constant vertical load, respectively. In both cases the vertical load was measured at the top of soil sample.

Bearing Capacity of Eccentrically–Obliquely Loaded Footings Resting on Fiber-Reinforced Sand

This paper presents the method proposed to calculate the bearing capacity of a square footing under oblique and eccentric oblique loading condition (satisfying both shear failure and settlement criteria) resting on fiber reinforced sand layer underlain by sand with geosynthetic/fabric sheet at the interface. Large direct shear tests were carried out to investigate the shear strength parameters of sand and randomly distributed fiber reinforced sand (RDFS) and soil-plastic fabric sheet bond. The ultimate bearing capacity of RDFS was determined using direct shear results. Non-dimensional charts proposed by Kumar (Behaviour of eccentrically–obliquely loaded footing on reinforced earth slab. Ph.D. thesis, University of Roorkee, Roorkee, India, 2002) were used to consider the contribution of plastic fabric sheet in increasing the bearing capacity. Also, for calculating the settlement, horizontal deformation and tilt at a given pressure the regression analysis of plate load test data have been carried out. The predicted values of ultimate bearing capacity, settlement, horizontal deformation and tilt are compared with the experimental values which are in good agreement with each other. There appeared to be an increase in the residual shear strength and angle of internal friction of RDFS.

Influence of Optimized Tire Shreds on Shear Strength Parameters of Sand

This paper presents the usefulness of optimizing the size of waste tire shreds on shear strength parameters of sand reinforced with shredded waste tires. A relatively, uniform sand has been mixed with randomly distributed waste tire shreds with rectangular shape and compacted at 2° of compaction. Waste tire shreds were prepared with a special cutter in three widths of 2, 3, and 4 cm and various lengths for each shred width. Three shred contents of 15, 30, and 50% by volume were chosen and mixed with the sand to obtain a uniformly distributed mixture. In order to compare the shear strength of different sand.tire shred samples, two compaction efforts in terms of sand matrix unit weights of 15.5 and 16.8 kN/m³ were considered. The results show that the influencing parameters on shear strength characteristics of sand.shred mixtures are normal stress, sand matrix unit weight, shred content, shred width, and aspect ratio of tire shreds. With the selected widths of shreds, compaction efforts, shred contents, and the variations of aspect ratios, it is possible to increase the initial friction angle Φ1 up to 113.5%, that is Φ1 = 67°. The average value for the influence of aspect ratio variations on increase in friction angle of the mixtures for all tests has been found to be about 25%. These average values for lower and higher compacted samples containing different widths and aspect rations were 37.6 and 17.2%, respectively. It has been investigated that for a given width of tire rectangular shreds, there is solely a certain length, which gives the greatest initial friction angle for sand.tire shred mixtures. This is the main contribution of this paper.