Pile Material Research Articles

Modeling of soil-cement piles construction and testing

This article is devoted to laboratory studying of soil-cement piles. The main problems of the research are defined. The technology of pile establishing and factors that affect pile's material strength are described. The method of modeling deep soil mixing technology at laboratory with keeping soil behavior such as consistency and moisture of basement is explained. The influence of plasticizing additions on pile's material strength is experimentally studied. A set of pile samples with different composition were produced. Reference piles were produced of two cement types – portlandcement and portland-slag cement. Some piles were produced by mixing in plasticizing additions to binder. Cylindrical specimen of soil-cement were selected. The correlation that has been revealed shows the influence of plasticizing additions on soil-cement strength and consistency. It has been revealed that pile's body material strength depends on the depth of sinking. The findings of the experiment proved the validity of the suggested modeling method and efficiency of use of plasticizing additions.

Laboratory model tests on laterally loaded piles in plastic clay

This paper presents the results of laboratory model tests conducted to study the behavior of laterally loaded piles installed in plastic clay. The effects of different factors such as pile dimensions, pile material and method of installation were studied. The pile response is presented in terms of load–deflection curves, bending moment distribution, and the p–y curves. The load–deflection curves are generally non-linear specially for large length/diameter (L/d) ratios and large diameters. The ultimate lateral pile capacity increases with the increase in L/d ratio and the pile diameter. The maximum bending moment increases with the increase in L/d ratio and the pile diameter. The maximum bending moment occurs at a depth varying from 0·13L to 0·32L. The bending stresses at the ultimate load are much less than the yielding stress of steel and the flexural strength of concrete. This implies that the deflection controls the design of laterally loaded piles in plastic clays. The experimental p–y curves are different from the existing p–y curves for piles with small diameters and are approximately similar to the existing p–y curves for piles with larger diameters. The bored method of installation gives greater ultimate soil resistance than the preinstalled method for both concrete and steel piles. Overall this study showed that the laboratory model tests with relatively large diameter (>30 mm) can be used to give insight into the performance of laterally loaded piles installed in plastic clays.

Numerical Solution of Single Pile Subjected to Simultaneous Torsional and Axial Loads

AbstractTorsional loads on pile foundations are induced by the action of eccentric horizontal forces on the supporting structures. Such loading not only initiates twisting at the pile head but also reduces its axial capacity significantly with increased settlement of the foundation. Several theoretical and experimental investigations have already been carried out on piles under torsional load, as evidenced by the available literature on the subject, although contributions on the influence of combined torsional and axial loads on pile foundations are rather limited. This paper presents a novel numerical model (boundary-element method) to analyze the response of a single vertical floating pile subjected to simultaneous torsional and axial loads. The nonlinear stress-strain response of soil has been incorporated in the model by means of the hyperbolic model, whereas the pile material has been idealized as elastic–perfectly plastic. The effect of progressive pile-soil slippage at the interface is considered. ...

Numerical Solution of Single Piles Subjected to Pure Torsion

Torsional load on pile foundations is induced by the action of eccentric horizontal forces on the supporting structures. Such loading not only initiates twist at the pile head, but also reduces its axial capacity significantly associated with increased settlement of the foundation. Inadequate design of piles under torsion may lead to disastrous consequences. Although several theoretical and experimental investigations have already been carried out on piles under torsional load as evidenced from the available literature, there is ample scope for further contributions on the influence of torsional load on pile foundation. This paper presents a novel numerical model (boundary element method) to analyze the response of a single, vertical, floating pile subjected to pure torsional load. The nonlinear stress-strain response of soil has been incorporated in the model by hyperbolic correlation, whereas the pile material has been idealized as elastic–perfectly plastic. The effect of progressive pile-soil slippage at the interface is considered. Apart from predicting the load-displacement response with incremental angle of twist of pile under pure torsion, the profiles for shear stress and angle of twist and the depth of interface slippage are some of the salient features captured by the proposed model. Validation of the model developed by comparing with existing models and experimental data indicate the suitability and accuracy of the solutions developed. However, minor discrepancies in the solution appeared owing to the simplified assumptions of perfectly plastic postpeak soil behavior and the absence of residual stress in the soil owing to pile installation. The proposed model is also applied successfully to selected case studies on concrete piles (L/D ranged from 10–40) in medium-soft clay, medium-dense sand, and layered soil, and a set of design curves have been constructed.

A quasi-analytic model of the underwater sound signal from impact driving of an offshore semi-infinite pile

A quasi-analytic model is derived for the underwater sound signal radiated when an offshore pile is struck on its face by a hammer. The pile is modeled as a semi-infinite cylindrical shell of an elastic solid. The impact generates a pulse of vibration that travels down the pile at the longitudinal sound-speed. At a given distance below the pile face, the axial displacement after the peak has arrived decreases exponentially with time. There are two coupled equations of motion for the axial and radial displacements. A closed form expression is derived for the radiated sound pressure (which is proportional to the radial acceleration) in terms of the Poisson ratio and Young’s Modulus of the pile material, the hammer velocity, contact area between hammer and pile, pile radius, hammer mass, the pile’s longitudinal sound-speed, and the sound-speed and density of the external medium. This model is applied to a published scenario for which the radiated sound pressure had been computed using a Finite Element Model, but is found to produce a different result. Some assumptions used in the model are identified that may explain the difference.

Study on Calculation Method of Reinforced Embankment Bearing Capacity Based on Landslide Equilibrium Method

Foundation treatment is necessary when the construction is built on soft ground; Reinforcing is superior to many other methods when embankment is built on soft ground. This paper adopts slide block balance analysis of the composite foundation bearing capacity consisting of the horizontal reinforced and discrete material pile, while considering the level friction resistance from the reinforcement and ground on the foundation bearing capacity influence. and it is applied to practical engineering. The results show that the method is feasible.

Static and dynamic analyses of the stability of mining wastes (Ravaneti) in the Carrara marble area (Apuan Alps, Italy) / Analiza statyczna i dynamiczna stabilności hałd odpadów górniczych w regionie wydobycia marmurów Carrara (Alpy Apuańskie, Italia)

Abstract The problem of the stability of “ravanetos” (debris piles of mining waste material extracted from the Apuan Alps, Italy) is very relevant, because of the consequences a landslide would have on the people and the existing civil infrastructures throughout the territory. In this work, the stability of two ravanetos that can be considered as representative of those in the Carrara area has been studied: the Polvaccio ravaneto, a recent type of debris pile and the Torrione-Tecchione, an old debris pile at present undergoing re-naturalisation. The study using the LEM (Limit Equilibrium Method) in a static and pseudo-static field, has made it possible to first carry out a back-analysis to define the most probable apparent cohesion and friction angle values of the material that makes up the ravanetos. Subsequently, it was possible to determine the intensity of the seismic wave that would be able to lead the two ravanetos to limit stability conditions and to determine the probability of such a seismic wave occurring in the next 50 years. A more accurate analysis, carried out with a numerical method in the dynamic field, of the most critical condition (the Polvaccio ravaneto) has led to more conservative results (higher safety factors) than those obtained with the LEM. This result allows us to reveal how the LEM can be considered a cautionary instrument to judge the stability of debris piles during a seismic event and that the likelihood of a landslide occurring in the two studied representative ravanetos over the next 50 years is very slim.

Parameter Analysis of Foundation Settlement Considering Interaction between the Pile and Soil

The assignment is using Drucker-prager elastic-plastic constitutive model for vertical load to analysis the interface behavior between soil and pile materials. Through the parameter analysis, in actual projects, the pile diameter and properties of pile endpoint soil have definite influences upon stress distribution and deformation of foundation. The conclusions obtained here could be taken for reference by similar projects.

Analysis of Behavior of Composite Foundation with Sparse Pile to Control Settlement

The composite foundation with sparse piles to control settlement has been used to rapid construction and strict deformation of the structure widely currently, which can enhance the efficient of load transfer and decrease the differential settlement used with the geosynthetic. Considering the confine of analytical solution and the traditional method with a changeless modulus of geosynthetic and pile, the effects of the height of fill, the elastic modulus of geosynthetic and pile material on the differential settlement, embankment soil arching effect and tensioned membrane effect etc. are investigated using the computer code ABAQUS in this paper. The results indicate that the modulus of geosynthetic and pile has a notable influence on the differential settlement and the arching effect, which should be considered in the design. At the same time, the maximum tension in geosynthetic occurs near the edge of the pile cap.

Analysis of Settlement of Composite Foundation with Sparse Pile to Control Settlement

The embankment soil arching effect of the composite foundation with sparse piles to control settlement is caused by the differential settlement between the embankment fill and the piles. So, the settlement is an important behaviour of the composite foundation. The effects of the height of embankment, the elastic modulus of geosynthetic and pile material, the stiffness of cushion and substratum, the pile cap and the distance of piles on the settlement are investigated using the computer code ABAQUS in this paper. The results indicate that the maximum settlement and differential settlement decrease with the elastic modulus of geosynthetic, the stiffness of cushion and substratum. The maximum settlement decreases and the differential settlement increases with the elastic modulus of pile material. At the same time, the differential settlement of the embankment surface decreases with the height of fill and there will be an equal settlement plane when the fill reaches certain height. In addition, the distance of piles has a more significant influence on settlement than the dimension of pile cap.

The Coupling Effect of Composite Material with Foundation Pile and Soil Mass

The computer-aided design method is used in modeling for the interaction between pile and geotechnical material soil. The behavior of the shear coupling springs is identical to the shear behavior of a grouted cable. Then a numerical model is founded by FLAC3D, deformation and stress responses are obtained as well as the mechanical response of pile during calculation, whose result reveals the mechanism of pile with soil under the load of gravitation and load transferring mode along pile shaft for different ground surface surcharge load, during simulation, the soil consists of two types, the less consolidated soil and normal consolidated soil, both the negative skin friction stress and positive skin friction stress are studied.

Early stages of mechanical deformation in indium phosphide with the zinc blende structure

Nanoindentations were performed on a cubic semiconductor using a cono-spherical diamond tip with a 260 nm radius. The tip produces a single point of contact with the crystal surface allowing indentations with nano-scale dimensions. The early stages of deformation on (100) InP with the zinc-blende structure were observed to happen by the sequential introduction of metastable dislocation loops along the various slip planes directly beneath the point of contact. Locking of the dislocations loops forms a hardened region that acts as an extended tip during subsequent indentation, eventually leading to multiple bulk-like displacements (pop-in events) and to material pile up in the vicinity of the indentation pit. The first pop-in marks the transition of deformation from the nanometer to the micrometer scale.

Experimental Research on Strength Characteristics of Bulky Rock Material with Different Coarse Grain Content in Waste Pile of Mine

Bulky rock material of waste pile was composed of discarded rock and soil which was blasted and stripped from stope. It was characterized by dispersibility, complexity and variability. Shear strength index of bulky rock material was the main basis for analyzing slope stability of the waste pile. After the study on bulky rock material with different coarse grain content by indoor direct shear test, the results indicated that there was no obvious peak strength during the shear process, and variation of the shear displacement was slight in initial horizontal loading stage. Horizontal loading increased slowly and shear displacement had obvious change when shear displacement exceeded 5mm. Under the same normal stress, shear modulus G0.01 increased with the increase of coarse grain content when shear strain of specimen is 1/100. Shear modulus G0.01 of the specimen with same coarse grain content increased with the increase of normal stress, varying sensitive of G0.01 reduced when coarse grain content was larger. When the specimens with same coarse grain content were under failure, the shear modulus Gfailure was smaller than G0.01. Cohesive force c of the bulky rock material began to increase and then decrease with the increase of coarse grain content, and reached its maximum of 31.25KPa when the coarse grain content was 70%, internal friction angle increased with the increase of coarse grain content.

Evaluation of geophysical mass flow models using the 2006 block-and-ash flows of Merapi Volcano, Java, Indonesia: Towards a short-term hazard assessment tool

The dynamics and depositional processes associated with block-and-ash flows (BAFs) are most commonly inferred to be a function of granular or inertial grain flow, similar to debris flows and cold rock avalanches. Existing geophysical mass flow models are either based on frictional (Mohr–Coulomb) behavior (the Titan2D model developed at the State University of New York at Buffalo, USA) or another rheological law (i.e., a constant retarding stress), eventually adding some viscous and turbulent components (the VolcFlow model developed at the Laboratoire Magmas et Volcans, Clermont-Ferrand, France). The 2006 BAFs of Merapi present a rare opportunity to test these two well-established models against a well-constrained field example. Integration of high-resolution field-based data into numerical simulations allows the validity of these models to be tested and rapid quantification of best-fit input parameters. We first show that with the incorporation of spatially varying bed friction angles, Titan2D is capable of reproducing the paths, runout distances, areas covered and deposited volumes of the 2006 Merapi flows over highly complex topography. However, some discrepancies with field data are noted and the velocity and travel time of the flows do not match entirely. Using a single free parameter (a constant retarding stress), simulations obtained with the VolcFlow model also reproduce the morphology and distribution of the natural deposits as well as the time of emplacement and velocities of the flows. The results suggest that the performance of these models in simulating actual events is critically dependent on: (1) the calibration of the model by using extensive field-based data such as deposit distribution, and processes of flow generation, transport and deposition; (2) the incorporation of a suitable numerical topographic dataset (i.e., high-resolution digital elevation model), and (3) the choice of input parameters, such as location and volume of the initial pile of material and source characteristics (single or multiple dome-collapse, dome-collapse duration and total volume of collapsed material). Sensitivity analyses and inundation maps based on the probability of impact were used to produce a suite of potentially inundated areas from future gravitational dome-collapse events affecting the Gendol valley and adjacent areas on the southern flank of the volcano. Our results provide the basis for defining hazard zonations of key areas at risk from BAFs which will be generated during future comparable eruptions at Merapi.

Uric Acid and Soluble Protein Content of Feces from Three Species of Subterranean Termites (Isoptera: Rhinotermitidae)

Like all animals, termites must dispose of excess nitrogen from protein and purine digestion and metabolism. Nitrogenous wastes in insect feces are primarily ammonia or uric acid (Cochran 1985, Chapman 1998). Ammonia is often the primary nitrogenous waste product of insects that live in aquatic or very moist environments. For insects that live in dry habitats, or need to conserve body weight for flight, or have a dry diet, uric acid is typically their main nitrogenous waste product (Chapman 1998, Cochran 1985). Although termites are uricotelic, feces of a subterranean termite, Reticulitermes flavipes Kollar, were reported to have only trace amounts of uric acid (Potrikus & Breznak 1980a). Termites are coprophagous (Waller & LaFage 1987), but experimental data is lacking regarding the nutritional benefit termites receive from ingestion of their feces. Nitrogen in the feces would be of nutritional value to the xylophagous subterranean termite since wood is very low in nitrogen. Fecal protein has been suggested as a source of dietary nitrogen for termites (Nation 2002), but amounts of fecal protein have not been measured. The current study aimed to determine levels of uric acid and soluble proteins in the feces of 3 subterranean termite species, and in turn consider how these biomolecules are involved in termite digestion and nutrition. Reticulitermes virginicus Banks and R. flavipes were collected from forested areas of Pearl River County, Mississippi, and either stored in the laboratory in original nest sapwood, or separated from wood for assay within 24 h after field collection. Coptotermes formosanus Shiraki were collected in Pearl River County from a bucket trap. Soluble protein levels of whole termite workers and fecal samples were determined using Bradford reagent with a bovine serum albumin standard (Sigma-Aldrich, St. Louis, Missouri). For whole termite samples, 3 groups of 10 live workers were weighed, added to separate 1.5 ml centrifuge tubes, and ground with a micropestle. After 1 mL deionized water was added, tubes were vortexed and centrifuged 5 min at 20,600 g. Soluble protein levels in adult termites were determined spectrophotometrically at 595 nm following the standard Bradford assay procedure provided with the reagent. For determination of soluble protein levels in feces, the micro Bradford assay procedure was used. Small piles of fecal material were collected as described in Arquette & Rodriguez (2011) from laboratory arenas without food. After determination of fresh weight, feces were prepared for protein assay as for whole termite samples. Uric acid levels from feces and 3 groups of 10 whole termites were determined using a procedure detailed in Arquette & Forschler (2006). Data for uric acid and soluble protein levels are presented using the same units reported in earlier papers (Potrikus & Breznak 1980a; Arquette & Forschler 2006; Arquette et al. 2006). Uric acid was not detected in feces of 7 of 9 populations assayed (Table 1). The 2 populations measuring trace amounts of uric acid in the feces had been kept in laboratory culture for approximately 1 year, whereas other groups were assayed soon after field collection. Fecal soluble protein levels ranged from about 1 to 5 percent fresh weight (Table 2).

Gravity's effect on landslides: A strike against Martian water

A pile of sand, gravel, or other granular material takes on a familiar conical shape, with the slope of the pile's walls coming to rest at the static angle of repose. If the material exceeds this angle, it will trigger an avalanche, tumbling down until it comes to rest at the dynamic angle of repose. Static angles of repose for coarse, angular materials tend to be around 40° from the horizontal, while smooth grains are stable at up to 20°. As largely a matter of geometry, grain properties, and internal friction, scientists have assumed these two angles of repose are fixed for a given substance. Observations of the angles of gully walls on Mars, found to be too shallow for the materials involved, have been used to argue that surface water must have played a part, either lubricating landslides or depositing the material directly. However, research by Kleinhans et al., using the parabolic flight of an airplane to test the effect of gravity on angles of repose, demonstrates that water need not have been present.

Effect of Local and Global Scour on Lateral Response of Single Piles in Different Soil Conditions

Marine structures, offshore platforms and bridge piers are usually supported on foundation piles. These piles are subjected to lateral loading due to wind, waves and currents. Piles installed in marine or river environments are susceptible to scour depending on wave and current characteristics and soil types. In this paper, the effect of local and global scour on behavior of laterally loaded piles installed in different soil conditions has been investigated. Finite element model (FEM) using the software program PLAXIS and Winkler model using the software program LPILE were used in the analyses. Different parameters were investigated such as soil types, scour depth, scour hole dimension, pile material, submerged condition, magnitude of lateral load and load eccentricity. The results showed that scour has a significant impact on piles installed in sand and a less significant impact on piles installed in clay. Global scour has a significant impact on pile lateral displacement and bending stresses. The effect of scour is more significant if piles are subjected to large lateral loads due to the nonlinear response of pile-soil system. Effect of scour of stiff clayey soils on piles is more pronounced than that of soft clayey soils.

Post-mining solutions for natural stone quarries

After-use solutions for natural stone quarries were studied for planning possible ways of using an abandoned (some other word might be better) quarry area. Characteristics of a natural stone quarry include physically stable quarry faces and benches created by quarrying, a water pond at the bottom of the quarry, and piles of leftover stone material. These features can be utilized as central elements in the quarry after-use. Scuba diving, climbing, and forestry are traditional and affordable afteruse alternatives, while fish or crab farming, rock building, storing, and amusement parks are more challenging solutions. The quarry can also be used for culture, learning, and research purposes.

강관합성 현장타설말뚝 머리의 수평하중-변위 거동 분석

To analyze the lateral load-deflection behavior of steel-concrete composite drilled shafts, a series of lateral pile load tests were performed. The test results were compared with the results from various analytical methods for lateral pile behaviors using the coefficients of subgrade reaction () estimated by pressuremeter test (PMT) and standard penetration test (SPT). As a result, it was found that the analytical methods using the estimated by SPT N value were not suitable for evaluating the pile head lateral load-deflections of the piles within the allowable deflection. However, the methods using the calculated from PMT were able to represent the initial lateral behavior at the head of the piles fairly well. Also, the method by the pressuremeter curve, which was applied directly to the p-y curve of the piles, offered a reasonable lateral behavior estimation by applying the correction factor to the pile materials.

Impact of Screening on Behavior during Storage and Cost of Ground Small-Diameter Pine Trees: A Case Study

Whole comminuted trees are known to self-heat and undergo quality changes during storage. Trommel screening after grinding is a process that removes fines from the screened material and removes a large proportion of high-ash, high-nutrient material. In this study, the trade-off between an increase in preprocessing cost from trommel screening and an increase in quality of the screened material was examined. Fresh lodgepole pine (Pinus contorta) was comminuted using a drum grinder with a 10-cm screen, and the resulting material was distributed into separate fines and overs piles. A third pile of unscreened material, the unsorted pile, was also examined. The three piles exhibited different characteristics during a 6-week storage period. The overs pile was much slower to heat. The overs pile reached a maximum temperature of 56.8°C, which was lower than the maximum reached by the other two piles (65.9°C and 63.4°C for the unsorted and fines, respectively). The overs also cooled faster and dried to a more uniform moisture content and had a lower ash content than the other two piles. Both piles of sorted material exhibited improved airflow and more drying than the unsorted material. Looking at supply system costs from preprocessing through in-feed into thermochemical conversion, this study found that trommel screening reduced system costs by over $3.50 per dry matter ton and stabilized material during storage.