Static Probing Research Articles

APPLICATION OF GEOTECHNICAL AND GEOPHYSICAL RESEARCH FOR SOIL CHARACTERIZATION

In the last few decades, modern geotechnical and geophysical in situ researches have been increasingly applied because they represent methods of quickly and instantly obtaining data on the properties and structure of the soil. Exploratory drilling is a research method that only obtains one-dimensional data, and compared to geotechnical and geophysical in situ research, it is relatively expensive and time-consuming. By combining all the research methods mentioned above, the most reliable and high-quality data for soil characterization is obtained. In this paper, examples of the application of geotechnical and geophysical research at two locations, Dugo Selo and Sesvetski Kraljevac, are processed. Applied geotechnical methods include, in addition to exploratory drilling, static cone penetrometer probing (CPTu), dilatometer probing (DMT) and dynamic heavy percussive penetration (DPH). From the geophysical investigations, 2-D geoelectric tomography (ERT) and multichannel analysis of surface waves (MASW) were performed. Also, an analysis of soil parameters obtained by exploratory drilling and in situ geotechnical methods was carried out. Undrained shear strength (cu) and compressibility modulus (M) were selected for comparison. The analysis shows that exploratory drilling results in lower values of the analyzed parameters on average compared to the results of in situ testing.

DEM investigation into the small-strain stiffness of bio-cemented soils

AbstractBio-mediated methods, such as microbially induced carbonate precipitation, are promising techniques for soil stabilisation. However, uncertainty about the spatial distribution of the minerals formed and the mechanical improvements impedes bio-mediated methods from being translated widely into practice. To bolster confidence in bio-treatment, non-destructive characterisation is desired. Seismic methods offer the possibility to monitor the effectiveness and mechanical efficiency of bio-treatment both in the laboratory and in the field. To aid the interpretation of shear wave velocity measurements, this study uses the discrete element method to examine the small-strain stiffness of bio-cemented sands. Bio-cemented specimens with different characteristics, including properties of the host sand (void ratio, uniformity of particle size distribution) and properties of the precipitated minerals (distribution pattern, content, Young’s modulus), are modelled and subjected to static probing. The mechanisms affecting the small-strain properties of cemented soils are investigated from microscopic observations. The results identify two mechanisms controlling the mechanical reinforcement associated with bio-cementation, namely the number of effective bonds and the ability of a single bond to improve stiffness. The results show that the dominant mechanism varies with the properties of the host sand. These results support the use of seismic measurements to assess the mechanical efficiency and effectiveness of bio-mediated treatment.

Application of the BP neural network algorithm to the ultimate bearing capacity test of building structures

The ultimate bearing capacity test effect directly influences the safety performance of the design of building structures. To enhance the safety of building structures, applying the BP neural network algorithm to their ultimate bearing capacity test is studied to improve the test effect. The shear wave velocity of the building structure during stress is collected using the static probing technique. The input samples of the BP neural network are the building structure’s shear wave velocity and construction parameters. They are processed by dimensionality reduction through principal component analysis. The firework algorithm is used to optimize the weight of the BP neural network. An early termination training method is designed, and the optimal weight is combined to train the BP neural network. After training, the samples are input after dimensionality reduction, and the building structure’s ultimate bearing capacity test results are output. Experimental results show that this method can effectively collect the shear wave velocity of building structures and complete the dimensionality reduction of samples. Under different coaxial stresses, this method can effectively measure the ultimate bearing capacity, about 3800 kN. After parameter optimization, the test value of this method is very close to the target value; that is, the ultimate bearing capacity test precision is high.

Imaging the mechanical properties of nanowire arrays

Abstract Dimensional and contact resonance (CR) images of nanowire (NW) arrays (NWAs) are measured using our newly developed microprobe CR imaging (CRI) setup. Then a reference method is employed to calculate the indentation modulus of NWs (M i,NW ) representing the elasticity of NWs, by measuring NWAs and reference samples at the same static probing force. Furthermore, topography is imaged in combination with CR and M i,NW separately by software, in which the z values indicate the topography of the NWs and the color bars show its CR or M i,NW . Then NWs’ topography relation to M i,NW is visualized. As typical examples, 3D imaging of topography and measurement of M i,NW is performed with Si<111> pillar arrays as well as Cu and ZnO NWAs. The novel method enables fast mechanical performance measurements of large-scale vertically-aligned NWAs without releasing them from their respective substrates. For instance, the diameter and pitch of the Si<111> pillars and the diameter of the Cu NWAs are in good agreement with the values measured by scanning electron microscopy (SEM). The position of ZnO NWs bunches grown at arbitrary sites on silicon can be identified with the help of combined topography and indentation modulus images. Furthermore, M i,NW measured by our homemade CRI setup agrees well with bulk values. Differences between the measured M i,NW and bulk M i values may be related to a size effect in NW elasticity.

Prediction of CPTu static sounding parameters based on DPH dynamic probing heavy test on the example of “the Praski terrace” sands inWarsaw title

This paper attempts to relate the parameters obtained from CPTu static sounding and DPH dynamic test conducted in non-cohesive alluvial deposits of the Vistula River. The investigation was carried out in eight test stations located on the left bank of the Vistula River in Warsaw. The presented theses were based on the results of static CPTU and dynamic DPH tests obtained at 8 test stations. Additionally, in order to associate the obtained sounding results to the lithological type of the tested medium, drillings and grain size analyses were performed. The correlation of the different test methods stems from the need to identify and explain observed discrepancies against the background of different geological conditions, such as moisture content or grain size distribution. The comparative analysis of the parameters obtained from static and dynamic probing, is relevant to the alluvial sediments formed the lower over-flood terrace (called “the Praski terrace”) of Warsaw. Based on the comparison this paper proposes a correlation between the cone penetration resistance the sleeve friction and the number of blows, expressed by the functional relationship. Differences in the matching formulas were shown depending on the saturation of the tested sediments. Correlations were referred to a soil type, which enabled to specify the range of applicability of the proposed relationships. The results of the study were further used to show their diversity using statistical methods. This made it possible to assess the variability of the parameters of the non-cohesive soil, which forms a single lithogenetic unit.

Finding reserves of bearing capacity of bored piles

In recent years, due to population growth plans and accelerated economic development, high-rise buildings have become increasingly common in many cities and megapolises around the world. Due to the development of engineering construction, the type and technology of pile footing, which form the basis of such buildings, as well as the control of both single piles and a group of piles, have been significantly improved. At the same time, today the task of adequate assessment of the pile load capacity and justification of effective methods of revealing the reserves of its increase is actualized, because the manufacturing technology is constantly developing, in addition, often the functional purpose of the building itself, the type and intensity of the loads acting on it change. In view of the above, the purpose of the article is to investigate modern scientific- methodological approaches to search for reserves of bored pile load capacity. In order to carry out the study, the article used numerical methods for analyzing the stress-strain state of piles and means of the software package "Plaxis 3D Faundation". In the course of empirical experiments, it was found that the most acceptable results in the load testing of bored piles are given by the Shen method. Besides, the comparison of the results of static probing and static tests with theoretical calculations allowed to reveal the reserves of the actual pile load capacity, and also to determine on what parameters of its installation and characteristics the difference in load capacity depends more: the soil sciences in the pile base, pile diameter, pile length. Theoretical significance of the obtained results lies in the development of methodology for identifying reserves to increase the load capacity of bored piles. Conclusions have practical value that can be used in the process of laying the foundation of high-rise buildings to optimize the number and geometry of pile placement taking into account the reserve of their bearing capacity.

Heavy vibratory plate compaction of silty sand: A field study

Heavy vibratory plate compaction is an efficient technique for improvement of granular soils. However, its practical application is limited by insufficient knowledge about the compaction process and the optimum procedure of execution. In this study, compaction tests were conducted in the field with a 40.5-ton heavy vibratory plate compactor. The site consisted of partially saturated, overconsolidated medium-dense silty sand and sandy silt. Such conditions can generally be characterized as difficult for vibratory compaction. The objective of the tests was to study the compaction depth and the influence of treatment layout, duration of compaction, and vibration frequency. In-situ measurements conducted before, during and after treatment included static cone penetration tests, flat dilatometer, and heavy dynamic probing. The in-situ tests showed a statistically significant compaction after treatment. The main conclusions highlight the importance of a sufficient centrifugal force of the vibratory hammer to cause disconnection between the plate and the soil. Other important parameters are the vibration frequency and the duration of treatment, which can be optimized by field monitoring. Full coverage of the ground surface is required for compaction of the entire soil volume. It was also found that the compaction depth corresponds to the side length of the plate, in line with previous studies.

SCIENTIFIC AND TECHNICAL SUBSTANTIATION OF SOIL BASES STRENGTHENING WITH REINFORCED SOIL-CEMENT PILES

Purpose. The aim of the work is to substantiate the technological parameters of effective use of reinforced soil-cement piles obtained by jet mixing technology. Such studies are needed to determine the possibility of increasing the bearing capacity of pile foundations in the body of earthen structures of buildings and roads. Methodology. Determination of bearing capacity of reinforced soil-cement piles was carried out by reasonable choice of structure, soil base, material, depth of piles in accordance with engineering and geological conditions, structural scheme of the structure and method of their arrangement. Findings. Significant differences in soil engineering and geological elements in plan and depth necessitated an in-depth study of soil characteristics, so it was decided to determine their strength and deformability based on static probing of reinforced piles. Analysis of the results of static studies showed that the soil-cement pile, reinforced with a reinforcing frame, has a higher bearing capacity in soil and material, and the unloading branch confirms the fact that in specific conditions the soil and piles work in elastic mode. Originality. It consists of the obtained dependences of the change of vertical loads on the reinforced soil-cement pile, created on the basis of brown mixing technology. Graphs of the dependence of the values of deformations occurring during the action on the reinforced soil-cement pile under static loading and unloading are obtained. Practical value. In practical conditions, the solution for the manufacture and testing of static load of the experimental reinforced soil-cement pile was implemented at the construction site. The manufacturing technology is designed so that the spatial frames of the soil-cement element with a length of 5…7 meters are immersed under their own weight, and the frames of 12 and more meters are lowered with a vibrator.

Assessment of physical and mechanical indicators of sandy soils by static and dynamic probing data

In the work, on the basis of the analysis of tabular data of both current and former normative documents on engineering-geological surveying and design of soil bases and foundations of structures and literary sources, as well as own experience, a graphical and analytical interpretation of determination of the basic values of physical-mechanical normative and calculated indices of sandy soils according to the indicators of static q, MPa and dynamic RD, MPa probing are given. The use of the proposed empirical analytical dependencies can significantly accelerate the processing of field engineering-geological surveying and provide more objective comparison of such soils condition at different objects while making design decisions. They can also be used in the development of resident software, in case of its development and manufacture for automatically calculating the values of the physical and mechanical parameters of sandy soils. The obtained analytical dependencies are presented in the form of two tables for different types of sandy soils: separately for surveying that are carried out using both static and dynamic probes. And the graphs allow you to visually compare these dependencies, that can provide new material for further scientific generalizations and conclusions in the field of soil science and mechanics.

Щодо оцінки значень фізико-механічних показників піщаних ґрунтів за даними статистичного динамічного зондування

Introduction. During engineering and geological surveys at the stage of objects designing or to assess the condition and bearing capacity of a natural foundation or earthwork during the operation stage, static or dynamic probing methods are often used. Results. Based on the analysis of tabular data, both current and former regulations and literature sources, as well as own experience, graphical and analytical interpretation of the values of the main physical and mechanical parameters of sandy soils according to static and dynamic probing data is given. Conclusions. The obtained new empirical and analytical dependences allow significantly accelerating the processing of field engineering and geological surveys data and providing more objective comparison of the condition of such soils at different sites during design solutions taking for preliminary calculations of the buildings and facilities foundations.

Comparative Analysis of Cone Resistances in Cone Penetration Test (CPTu) and Dynamic Probe Heavy Test (DPH)

This paper presents a comparison of geotechnical soil testing with the use of Piezocone Penetration Test (CPTu) and Dynamic Probing Heavy (DPH) in a uniform coarse-grained medium located in southwest part of Poland. The soil medium was identified in detail. The interpretation of results included both grain-size analysis of samples from drillholes and soil behavior type results obtained from the Robertson nomograph (Soil behaviour type from the CPT: an update. In: 2nd international symposium on cone penetration testing, USA, 2010). Cone penetration resistances qc obtained in the static CPTu tests were compared with the results of dynamic probing N10H and of dynamic point resistance qd obtained in the dynamic DPH tests. The evaluation of soil density index was based on both dynamic DPH and static CPTu probing. The obtained results were analyzed and plotted in a form of graphs corresponding to the Eurocode 7 and other works describing coarse-grained soils.

Acoustic Emission of Frozen Soils under Quasi-Static Mechanical and Cyclic Thermal Loading

The effects of acoustic emission (AE) in soils during freezing and thawing under cyclic thermal and quasi-static mechanical loading have been studied. The composition and characteristics of the developed instrumentation set are presented. The informative AE parameters and primary data processing approaches were justified. The acoustic emission patterns of soil material behavior under the variable thermobaric conditions were obtained. The comparative tests were performed using static probing and ultrasonic scanning.

Elastic wave propagation in dry granular media: Effects of probing characteristics and stress history

Elastic wave propagation provides a noninvasive way to examine polydisperse, frictional granular materials. The discrete element method (DEM) allows for a micromechanical interpretation of the acoustic response. Using experimentally measured granular microstructures as input, after straining them to various cyclic, oedometric compression states, we numerically perform both static and dynamic probing to deduce elastic moduli/wave velocities from small-strain modulus degradation and time/frequency-domain signals.Static probing allows to understand the path dependency of the elastic moduli, i.e., the stress response to small strain increments, as well as their degradation behavior, for medium-to-large probing strains. Complementarily, dynamic probing provides insights into the acoustic properties (dispersion relations) at different wavelengths, for various probing characteristics. The wave velocities extracted from the space-time evolution of particle motion are sensitive to travel distance and input waveform, but converge to the same long-wavelength velocities far away from the source, where short wavelengths are dispersed and attenuated. Analyzing the same space-time data in the frequency domain leads to the same results, much less dependent on the probing characteristics than in the time domain, and much faster than static probing.Concerning the dependence on the stress history, as expected, the moduli (and wave velocities) increase under initial oedometric compression. First unloading reveals a significant plastic, irreversible decrease of the moduli, whereas reloading along the oedometric path leads to a reduced degradation. The elastic regime, i.e., the probing strain at which the moduli begin to degrade, gradually decays, as the change of the deviatoric to mean stress ratio increases towards its maximum where plasticity/irreversibility is strongest. Interestingly, the moduli from static probing show that the degradation curves immediately before and after a load reversal are almost identical, suggesting that the elastoplastic behavior is symmetric around the turning point for tiny strains, as also confirmed by identical vibrational densities of states at reversal. Remarkably, the moduli, their degradation behavior and the shapes of the dispersion relations (normalized by their large wavelength limits), are all very similar during unloading and reloading, whereas they reflect a strongly different material behavior under initial loading.

Optimizing static and adaptive probing schedules for rapid event detection

We formulate and study a fundamental search and detection problem, Schedule Optimization, motivated by a variety of real-world applications, ranging from monitoring content changes on the web, social networks, and user activities to detecting failure on large systems with many individual machines.We consider a large system consists of many nodes, where each node has its own rate of generating new events, or items. A monitoring application can probe a small number of nodes at each step, and our goal is to compute a probing schedule that minimizes the expected number of undiscovered items at the system, or equivalently, minimizes the expected time to discover a new item in the system.We study the Schedule Optimization problem both for deterministic and randomized memoryless algorithms. We provide lower bounds on the cost of an optimal schedule and construct close to optimal schedules with rigorous mathematical guarantees.

Methods for Estimating the Load Bearing Capacity of Pile Foundation Using the Results of Penetration Tests - Case Study of Road Viaduct Foundation

Studies using static probing guarantee the precision of measurements and reliability of results which are of fundamental importance for the entire design process. More and more new modeling and calculation schemes and concepts using the direct results of static probing have been developed and still are being developed based on direct probing parameters, which is the result of a very rapid development of this approach, and increasingly more common use by designers and constructors in various research centers working in the field of soil mechanics, geotechnics and geoengineering.This paper presents the estimation of load bearing capacity based on direct parameters obtained from the results of static probing test of ground, which are mainly used in engineering in Poland and in Europe, and which form the basis for new ideas and concepts for calculation. The calculations of the reference pile foundation based on the results of the actual study conducted for the road overpass in the expressway currently under construction near Miłomłyn town in Warmia-Mazury province are shown in the paper using the described methods.

Using Electrical Resistivity Tomography (ERT) as a tool in geotechnical investigation of the substrate of a highway

Abstract Geological and geotechnical engineering field tests, like structure drillings and dynamic (DPL, DPSH) or static probing (CPT), are considered for a fundamental source of information about soil and water environments. Since Eurocode 7 has been introduced, it has become more common to use also dilatometers (DMT) or pressure meters (PMT). Results obtained using all the mentioned tests are always of a discrete nature - information is provided in certain points in the field. However, they determine the basis for creating spatial models of geological structure and geotechnical condi- tions of a substratum. The range and number of investigations conducted (including drilling, probing and laboratory tests) influence precision, in which a geological structure is identified and thus, also affect probability of compatibility between spatial model and real geological conditions of a substratum. In the paper, results of non-invasive electrical resistivity tomography (ERT) method are presented, comprising 2-dimensional image of a soil medium resistance. Electrical resistance is a parameter that reflects diversification of a soil medium, considering its lithological aspect. In addition, when combined with drilling results, it can be used to accurate determination of boundaries between soil layers. Carrying out of ERT tests in the field during expressway construction contributed to identification of weak, low-strength soils like organic soils (peat, aggradated mud) and of soft consistency cohesive soils. These kinds of soil are the main cause for unacceptable deformations appearing in the new road engineering structure.

Deformation characteristics of the Jurassic clayey soils of Moscow

The upper-Jurassic soils of Moscow, which are frequently the bed and medium on which underground structures and deep pits are installed, are examined. Archival materials derived from surveys are statistically processed using the theory of correlation-regression analysis, and correlation relations between the compression modulus based on plate-test data and the physical parameters and specific resistance of the soil under the tip of the probe are investigated during static probing. Factors for conversion from the compression modulus of the soils examined to the compression modulus as determined by a plate are obtained.

A dynamic method of evaluating the bearing capacity of foundations in tamped pits

A dynamic method is outlined for evaluating the bearing capacity of foundations in tamped pits. Results of investigations on an experimental construction site are discussed. Computational formulas are proposed for evaluation of the bearing capacity of foundations on the basis of data derived from tamping and static probing of soils.

Refinement of design rules for beds and foundations on soils prone to slump-type settlement

Suggestions are given for refinement of rules governing the design of beds and foundations on soils prone to slump-type settlement; these suggestions are based on consideration of additional settlements and zones of compression of the underlying soil stratum prone to slump-type settlement, calculation of the bearing capacity of piles from results of static probing of the soils, and determination of additional loads on the piles due to forces of loading friction throughout the mass of soil suspended on the piles.

Estimation of Pile Resistance in Soils Prone to Slump-Type Settlement from Results of Static Probing

Results are presented for static tests of precast piles 6–24 m long, and static probing of soils at experimental proving grounds. Negative-friction forces of soils prone to slump-type settlement and total pile resistance are estimated on the basis of data derived from static probing of the soils. The need for correction of individual positions taken in Body of Rules 50-102-2003 in conformity with Construction Rule and Regulation 2.02.03-85 is noted.