Geotechnical Engineering Parameters Research Articles

Prediction of relative density of carbonate soil by way of a dynamic cone penetration test

Relative density is an important parameter in geotechnical engineering and the dynamic cone penetration test has been widely used for its assessment. The currently established relationships between the dynamic penetration index and relative density might not be suitable for carbonate sediments due to their unique engineering properties. Therefore, 18 dynamic cone penetration model tests were conducted for carbonate coarse-grained soils. Simultaneously, 18 other laboratory model tests for quartz soils with similar gradations were carried out for comparison. The test results indicate that under the same relative density, the dynamic penetration index of carbonate coarse-grained soils is lower than that of quartz soils. In addition, the particle size and gradation of soils exert a greater influence on the dynamic penetration index of carbonate coarse-grained soils. Based on the test results and considering the influence factors mentioned above, two relationships between the dynamic penetration index and relative density are presented for carbonate and quartz soils, and these relationships could be used to evaluate the properties of soil backfills and base materials.

Effect of fabric on shear wave velocity in granular soils

The small-strain elastic shear wave velocity ($$V_S$$) is a basic mechanical property of soils and is an important parameter in geotechnical engineering. Recently, $$V_S$$ has been adopted as one of the indices for development of liquefaction charts. This implies that if a parameter affects $$V_S$$, it may also affect liquefaction resistance. Some of the parameters whose effects have been accounted for include relative density, stress state and geologic age. An important parameter that affects both liquefaction resistance and $$V_S$$ is fabric. Quantification of in situ fabric is still an open problem and hence, considerable judgement is needed in order to map laboratory test results to field conditions. In this paper, we conduct numerical simulations at the grain-scale to investigate the effect of fabric on $$V_S$$. We start by showing that two granular assemblies, with the same stress state and void ratio but different fabrics, can exhibit different trends in liquefaction behavior. Furthermore, via a numerical implementation of the bender element test, we obtain two distinct trends of $$V_S$$ anisotropy for the two granular assemblies. Finally, we consider three different fabric measures based on contact properties and explore correlations between $$V_S$$ anisotropy and fabric anisotropy. We also look at fabric tensors of the ‘strong’ and ‘weak’ network, respectively, of the granular assemblies. Our results suggest that for liquefiable soils, i.e., recent Holocene-age deposits with negligible cementation and with a stress history of seismic loading, a knowledge of $$V_S$$ anisotropy can give information about fabric anisotropy. A knowledge of in situ fabric could help in more accurately mapping laboratory test results to field conditions.

Seismic Performance of Ancient Masonry Structures in Korea Rediscovered in 2016 M 5.8 Gyeongju Earthquake

The Gyeongju Historic Areas, which include the millennium-old capital of the Silla Kingdom, are located in the region most frequently affected by seismic events in the Korean peninsula. Despite the numerous earthquakes documented, most of the stone architectural heritage has retained their original forms. This study systematically reviews and categorises studies dealing with the seismic risk assessment of the architectural heritage of the historic areas. It applies research methodologies, such as the evaluation of the engineering characteristics of subsoil in architectural heritage sites, site-specific analysis of the ground motions in response to earthquake scenarios, geographic information system (GIS)-based seismic microzonation according to the geotechnical engineering parameters, reliability assessment of dynamic centrifuge model testing for stone masonry structures and evaluation of seismic behaviour of architectural heritage. The M 5.8 earthquake that hit Gyeongju on September 12, 2016 is analysed from an engineering point of view and the resulting damage to the stone architectural heritage is reported. The study focuses on Cheomseongdae, an astronomical observatory in Gyeongju, whose structural engineering received considerable attention since its seismic resistance was reported after the last earthquake. Dynamic centrifuge model tests applying the Gyeongju Earthquake motions are performed to prove that it is not a coincidence that Cheomseongdae, a masonry structure composed of nearly 400 stone members, survived numerous seismic events for over 1300 years. The structural characteristics of Cheomseongdae, such as the well-compacted filler materials in its lower part, rough inside wall in contrast to the smooth exterior, intersecting stone beams and interlocking headstones are proven to contribute to its overall seismic performance, demonstrating outstanding seismic design technology.

Gradation-Dependent Thermal Conductivity of Sands

AbstractAlthough thermal conductivity is a widely applied parameter in geotechnical engineering, the effect of soil gradation on the thermal conductivity is not well understood. Thermal needle test...

Case study: using the point load test to estimate rock strength of tunnels constructed by a tunnel boring machine

Rock strength is one of the most important parameters in geotechnical engineering. During excavation using a tunnel boring machine (TBM), a rapid and effective method to estimate rock strength is needed. The TBM muck produced during excavation contains blocky fragments which are suitable for a point load test (PLT). To use the PLT on blocky fragments to estimate rock strength, it is necessary to find the relation between the point load strength (PLS) of blocky fragments and uniaxial compressive strength (UCS) of surrounding rocks. In the present study, PLT was performed on both blocky fragments and core samples of limestone for the Yinsong Water Conveyance Project, China. The UCS of limestone was acquired. The PLS of blocky fragments and core samples was compared. The results show that the blocky fragments’ PLS is lower than that of core samples; the declining ratio depends on the fractured degree of sampling sites; blocky fragments with width and thickness in a certain range are suitable for estimating rock strength; and when the size of the blocky fragment exceeds a certain range, it means the blocky fragment was not generated from the tunnel face. The limestone core samples simultaneously drilled from side wall have an average conversion factor from PLS to UCS of 24.61. The mean conversion factor from PLS of blocky fragments to UCS of limestone in the present study is 40.38.

Modelling and mapping of landslide hazard using remote sensing and GIS techniques

This research examines the use of GIS and remote sensing techniques to model landslide hazard and its risk assessment in and around Wau–Bulolo. In achieving this, risk evaluation is carried out with the use of eleven geotechnical engineering parameters which include altitude, slope, aspect, rainfall, lithology, soil erodibility function, landform, distance from river, distance from road, earthquake magnitude, and land use/ land cover to generate and calculate landslide susceptibility zones and risk zones. Landslide vulnerability of Wau–Bulolo district in Morobe province was assessed using the weighted linear combination (WLC) method. The study area shows the distribution of the five vulnerability/susceptibility classes ranking from very low (1) to very high (5). Areas with very high landslide vulnerability zones are found in the northern and north-eastern of the study area compare to southern parts have very low vulnerability areas. From the calculations 12.49% of area is at very low risk, 30.33% at low risk, 32.84% of moderate risk, 11.58% of high risk and 14.76% of very high risk area coverage.

Optimization techniques for identifying soil parameters in geotechnical engineering: Comparative study and enhancement

SummaryA comparative study of optimization techniques for identifying soil parameters in geotechnical engineering was first presented. The identification methodology with its 3 main parts, error function, search strategy, and identification procedure, was introduced and summarized. Then, current optimization methods were reviewed and classified into 3 categories with an introduction to their basic principles and applications in geotechnical engineering. A comparative study on the identification of model parameters from a synthetic pressuremeter and an excavation tests was then performed by using 5 among the mostly common optimization methods, including genetic algorithms, particle swarm optimization, simulated annealing, the differential evolution algorithm and the artificial bee colony algorithm. The results demonstrated that the differential evolution had the strongest search ability but the slowest convergence speed. All the selected methods could reach approximate solutions with very small objective errors, but these solutions were different from the preset parameters. To improve the identification performance, an enhanced algorithm was developed by implementing the Nelder‐Mead simplex method in a differential algorithm to accelerate the convergence speed with strong reliable search ability. The performance of the enhanced optimization algorithm was finally highlighted by identifying the Mohr‐Coulomb parameters from the 2 same synthetic cases and from 2 real pressuremeter tests in sand, and ANICREEP parameters from 2 real pressuremeter tests in soft clay.

In situ determination of hydraulic conductivity in Yangtze Delta deposits using a modified piezocone model

In order to more precisely determine the in situ hydraulic conductivity of soils as an essential parameter in geotechnical engineering, this article presents a new method based on piezocone tests. In light of results obtained from a series of classical numerical simulations of piezocone dissipation tests and in situ tests, the modified direction and value assumptions of excess pore water pressure distribution are fundamental: (1) the flow surface of pore water is assumed to be cylindrical in shape at larger scales, and (2) the initial state of induced excess pore pressure is assumed to satisfy a negative exponential distribution in dissipating. After detailing the existing approaches, a comparison of data in the Yangtze Delta region between them and the proposed method based on graphical and statistical analysis has been accomplished; the comparison revealed the accuracy and validity of the proposed method, with five indices utilized, including a new relative error index. The reasonable assumptions, logical derivation and mathematical analysis together indicate the academic value and application potential of the proposed method.

Bearing Capacity of Circular Footing on Sand Deposit

Bearing capacity and settlement are two important parameters in geotechnical engineering. The bearing capacity of circular foundations on sandy soils is important to geotechnical practicing engineers. Design of foundations includes soil parameters and bearing capacity of foundation. This paper presents the results of laboratory experimental model tests of circular footings supported on sand deposit under static load. The finite element software Abaqus is used to compare the results. The effects of the relative density of the sand (30%, 50%, and 70%) and the diameter of circular footing (75 mm and 100 mm) are investigated. It can be concluded that the experimental test results fit quite well with the results of numerical method.

Application of the Arrhenius Equation in Geotechnical Engineering

The reliable measurement of geotechnical properties in cold regions should account for their fluctuations with temperature. The objective of this paper is to introduce a chemical model based on the Arrhenius equation that can predict the properties of materials as their temperature changes. The model can monitor phases and reaction rates as they change with temperature. It has been already applied in the fields of geology, construction, chemistry, materials engineering, and food science. The application of the Arrhenius equation requires a reliable estimate of the activation energy. Therefore, this study also demonstrates several methods for evaluating activation energy in different contexts through summaries and reviews of previous research related to the Arrhenius equation. This paper may be of wide use in obtaining temperature-dependent parameters in geotechnical engineering.

Study on Lateral Earth Pressure Coefficient at Rest for Frozen Soils

The lateral earth pressure coefficient at rest, K0, is an important parameter in geotechnical engineering. There have been many studies for unfrozen soils; however, this is not the case for frozen soils, which impedes reasonable calculation concerning cold regions engineering. This paper introduces a novel triaxial apparatus for frozen soils with reference to that for unfrozen soils. The device is capable of performing experiments on frozen soil samples with K0 status under precisely controlled negative temperature. Two soils along the Qinghai-Tibetan highway are taken as study objects. K0 experiments are carried out with the apparatus and K0 is obtained under different testing conditions. It is found that temperature is a dominant factor in influencing K0 of frozen soils, while stress state and soil type should also be taken into account.

Study on the Compressibility of the Silt in Hangzhou, China

To investigate the compressibility of the silt, three soil samples are collected from Xiasha zone, Hangzhou, Zhejiang Province, China. The geotechnical engineering parameters of the silt soil are measured in the soil mechanics laboratory. Tests results show that the uniformity coefficient of the silt is 13.6, the natural density is 1.96t/m3, the moisture content is 17.0%, the plasticity index is 9.4, the compression coefficient varies from 0.06 to 0.40MPa-1, and the compression index varies from 0.015 to 0.108. Finally, the properties of the compression are studied, and find that the compressibility of the silt soil is very large, and the relationship between the initial void ratio and the logarithm pressure is linear.

Study on the Shear Strength Properties of the Silt in Hangzhou, China

To investigate the shear strength properties of the silt, three soil samples are collected from Xiasha zone, Hangzhou, Zhejiang Province, China. The geotechnical engineering parameters of the silt soil are measured in the soil mechanics laboratory. Tests results show that the uniformity coefficient of the silt is 13.6, the natural density is 1.96t/m3, the moisture content is 17.0%, the plasticity index is 9.4, the cohesion force varies from 20.8 to 28.3kPa, and the internal friction angle varies from 12.3 to 31.8degree. Finally, the properties of the shear strength are studied, and find that the relationship between the shear stress and the shear strain is conformity with the strain hardening curve, and the relationship between the shear strength and the vertical pressure applied on the soil samples is linear, and agrees with the Coulombs law.

Study on the Geotechnical Engineering Properties of Polluted Soil

To investigate the geotechnical engineering properties of polluted soil, ten soil samples are collected from Anqing copper ore, Anhui Province, China. The geotechnical engineering parameters of the polluted soil are measured in the soil mechanics laboratory. Tests results show that the natural density varies from 1.56 to 2.04t/m3, the moisture content varies from 15.36% to 27.87%, the modulus of the compression varies from 1.27 to 8.10MPa, the cohesion force varies from 32 to 210kPa, and the internal friction angle varies from 25.4 to 57.9 degree. Finally, the properties of the shear strength and the compression are studied, and find that the compressibility of the polluted soil is very big, and the relationship between shear strength and the normal pressure conforms to the law of Coulomb.

Numerical Solution to Identification Problems of Material Parameters in Geotechnical Engineering

The identification of material parameter in geotechnical engineering is a typical complicated nonlinear function optimization problem. The optimum inverse method based on ABAQUS is discussed in the paper. A new evaluation function is established which unites multi objective function to single objective function according to the actually measures and corresponding calculated results. The inversion model combining the Nelder-Mead algorithm and finite element method is proposed, in which the finite element program is embedded as a module in the Nelder-Mead algorithm. This approach is applied to the parameter identification of strongly weathered granite as an example. The results show that the calculated results are similar with the measured ones, which suggests that the reasonability of finite element identification for material parameters.

Geotechnical properties of deep oceanic sediments recovered from the hydrate occurrence regions in the Ulleung Basin, East Sea, offshore Korea

This study presents comprehensive geotechnical data of the natural marine sediments cored from the hydrate occurrence regions during the Ulleung Basin Gas Hydrate Expedition 1 (UBGH1), East Sea, offshore Korea in 2007. Geotechnical soil index properties of the Ulleung Basin sediments, including grain size distribution, porosity, water content, Atterberg limits, specific gravity, and specific surface area, were experimentally determined. These soil index properties were correlated to geotechnical engineering parameters (e.g., shear strength and friction angle) by using well-known empirical relationships. By performing standard consolidation tests on both undisturbed specimens (as recovered from the original core liner after hydrate dissociation) and remolded specimens, stress-dependent mechanical and hydraulic properties (e.g., compressibility and hydraulic conductivity) were measured. The experimental results provide important engineering parameters, and demonstrate the effect of hydrate presence and consequential dissociation to index properties, engineering parameters, and innate sediment structures.

A New Alternative for Estimation of Geotechnical Engineering Parameters in Reclaimed Clays by Using Shear Wave Velocity

Abstract The consolidation behavior of reclaimed clay can be categorized as large strain deformation. Findings from previous studies indicate that the effective stress and the void ratio are important geotechnical engineering parameters for the characterization of large strain consolidation behavior. However, existing in situ consolidation characterization methods of reclaimed clay cannot adequately estimate changes of the effective stress and void ratio during a consolidation process. This paper suggests an alternative method for estimating the geotechnical engineering parameters of reclaimed clays using a shear wave. An in situ self-weight consolidation process of reclaimed clay is simulated in laboratory while shear wave velocity is continuously measured. Experimental results show that there are single trends in relationships among the shear wave velocity, effective stress, void ratio, and geotechnical engineering parameters for a normally consolidated clay (e.g., reclaimed clay). As a practical application, the in situ parameters and the expected settlement are predicted by incorporating the obtained relationships with the in situ shear wave velocity. The predicted values are in good accordance with the values measured in field. Therefore, the proposed method can be used effectively for geotechnical engineering parameter estimations of reclaimed clay during/after self-weight consolidation with the aid of in situ seismic exploration techniques.

Prediction of Effective Porosity of Contaminated Fine Grained Soils Using Electrical Properties

Abstract The effective porosity is a required parameter for mass flow rate calculations in groundwater hydrogeology and movement of contaminants through clay liners. It is also an important soil parameter in geotechnical engineering. In this manuscript, a laboratory methodology based on electrical properties of soils is proposed to estimate the effective porosity of contaminated soils. Based on the cluster model proposed by Olsen 1962 and the three possible electrical current paths through soils, a three-element electrical model is proposed. Bulk electrical properties of a soil element were mathematically derived for input frequencies of 1–100 MHz. The bulk electrical properties of three soils at different confining pressures in both horizontal and vertical directions were measured for the said frequency range. The measured and the predicted bulk electrical properties of soil were compared; the predictions were used to establish effective porosity of the soil element. The predicted effective porosity values for three soils under different chemical environments were compared with those measured using tracer test. The comparisons show that electrical measurements could predict effective porosities of contaminated fine grained soils. These measurements can then be used to estimate in situ effective porosities, to be used in contaminant transport models.

Signal processing method for shear wave velocity measurement

Soil shear wave velocity (SWV) is an important parameter in geotechnical engineering. To measure the soil SWV, three methods are generally used in China, including the single-hole method, cross-hole method and the surface-wave technique. An optimized approach based on a correlation function for single-hole SWV measurement is presented in this paper. In this approach, inherent inconsistencies of the artificial methods such as negative velocities, and too-large and too-small velocities, are eliminated from the single-hole method, and the efficiency of data processing is improved. In addition, verification using the cross-hole method of upper measuring points shows that the proposed optimized approach yields high precision in signal processing.

Apparatus Induced Error in Hydraulic Conductivity Measurement Using a Lucite® Fixed Wall Permeameter

Abstract Hydraulic conductivity is the most variable parameter in geotechnical engineering. Although accurate measurement of hydraulic conductivity of fine-grained soil is not an easy task, it is often required to satisfy the legitimate requirements of various agencies regulating the design, construction, and operation of compacted clay liners. Results are sensitive to the experimental apparatus and testing procedure used for the measurement. As the flow volumes being measured are very small, any minute leakage of permeant during the test will significantly affect the results obtained. The quantification of a significant unexpected loss of permeant through fixed wall permeameters made of Lucite is documented and discussed in this paper.