Seismic Cone Research Articles

Stress-Based Model for Interpreting Shear Wave Velocity from Seismic Cone Penetration Tests in Unsaturated Soil

Shear wave velocity is an important parameter for estimating soil properties used in analyzing the dynamic response of soil to seismic loading. This paper focuses on developing a model for predicting shear wave velocity in unsaturated soils. The model was developed primarily for the interpretation of seismic cone penetration tests (SCPTs) in unsaturated soil to account for seasonal variations in moisture conditions. In practice, SCPTs typically occur over a period of days without the option of choosing a wet or dry period. The question becomes, if tests are conducted during a dry period, how can shear wave velocity corresponding to a wetter period be predicted, or vice versa? Answering this question was the primary motivation of this work. The work involved field testing with the seismic cone penetrometer during wet and dry periods and a focused study at three sites involving comparison between field and laboratory testing for shear wave velocity. The model presented in this paper is built upon the significant work of many other researchers with reference to new experimental data obtained by the authors. It is demonstrated that a stress-based model incorporating matric suction can provide reasonable predictions of shear wave velocity and provides a method to interpret the impact of changing moisture content on shear wave velocities determined with SCPTs.

Susceptibility to Liquefaction of Iron Ore Tailings in Upstream Dams Considering Drainage Conditions Based on Seismic Piezocone Tests

One of the critical challenges facing the mining sector is related to the prevention and mitigation of catastrophic incidents associated with its tailing dams. As mining tailings are very heterogeneous and field characterization is expensive and complex, geotechnical properties of these materials are largely unknown. The seismic cone penetration test (SCPTu) provides a field approach to estimate a large array of geotechnical information, including the liquefaction potential of tailing dams. Yet, the exploration of strain softening behaviors in geomaterials under undrained loading, utilizing the state parameter (ψ) inferred from SCPTu tests initially applied to soft soils, has been often used for mining tailings. This study is concerned with the implementation of a tailing classification system which uses the ratio between the small strain shear modulus and the cone tip resistance (G0/qt). A series of laboratory tests was executed, and three different methodologies were adopted to assess the effects of (partial) drainage conditions based on 531.26 m of SCPTu measurements conducted at three different upstream iron ore tailing dams in Brazil. Furthermore, the G0/qt ratio is integrated with ψ to assess the liquefaction tendencies of the investigated materials. The findings reveal the heterogeneous nature of the tailings, wherein indications of partial drainage are discernible across numerous records. Liquefaction analyses demonstrate that the tailings exhibit a contractive behavior in over 94% of the SCPTu data, confirming their susceptibility to flow liquefaction. Our findings are relevant for site characterization within iron ore tailing dams and other mining sites with similar geotechnical attributes.

Will Japan Sink? ———The Explanation of the Seismo-Geothermics

Using the local earthquake catalog of Japan, based on the author’s original Seismo-Geothermics and it’s working methods, and from the study of the stereoscopic image of seismic cone structure, the independence of seismic cone tectonic activity and the inheritance of volcanic activity, this paper draws a conclusion that the Japanese home islands will not sink as long as earthquake still exists, volcano is still active and their lava cones are still there. In this paper, based on the independence of seismic cone tectonic activities, the general relationship between strong earthquakes, volcanoes and seismic cone tectonics in Japan and its adjacent areas is preliminarily clarified. Relying on the mature seismic data in Japan, Interested parties may be able to find out the prediction methods of intracrustal strong earthquakes and seismic cone type volcanism as soon as possible through the principle and working method of Seismo-Geothermics.

The Dawn of Earthquake Prediction Research in China: A Case Study of Seismic Activity in the Tianshan Mountains

The paper adopts the Unified Earthquake Catalog of China and according to the Chen Lijun's Seismo-geothermcs and its working method, and studies the planar and three-dimensional distribution images, sequential processes, abnormal states in the last two years, the background of historical seismic activity and the influence of seismic cone tectonic environment in the Tianshan Mountains. In this paper, with reference to the author's experience in the global case study of intracrustal strong seismic activity, it is believed that the seismic geothermal anomaly of the Nantianshan seismic sub-seismic cone tectonic can be confirmed without error, so it is speculated that the intracrustal strong seismic activity of M6. 5-7 may occur in Aksu area in the next 1-2 years in the tectonic influence area, which is worthy of high vigilance and close attention. This strong earthquake prediction opinion has been verified by the M7. 1 earthquake in Aksu, Xinjiang on January 23, 2024, which deserves affirmation.

Distributed acoustic sensing for seismic surface wave data acquisition in an intertidal environment

The application of distributed acoustic sensing (DAS) for shallow marine seismic investigations is assessed, in particular with respect to the collection of seismic surface wave data in an intertidal setting. Appropriate selection and directional sensitivity of fiber-optic cables is considered and the measured data is validated with respect to conventional seismic data acquisition approaches, using geophones and hydrophones, along with independent borehole and seismic cone penetration test (SCPT) data. In terms of cable selection, a reduction in amplitude and frequency response of an armored cable is observed, when compared with an unarmored cable. For seismic surface wave surveys in an offshore environment where the cable would need to withstand significant stresses, the use of the armored variant with limited loss in frequency response may be acceptable from a practical perspective. The DAS approach also has indicated good consistency with conventional means of surface wave data acquisition, and the inverted [Formula: see text] also is very consistent with downhole SCPT data. Observed differences in phase velocity between high tide (Scholte wave propagation) and low tide (Rayleigh wave propagation) are not thought to be related to the particular type of interface wave due to shallow water depth. These differences are more likely to be related to the development of capillary forces in the partially saturated granular medium at low tide. Overall, this study demonstrates that our novel approach of DAS using seabed fiber-optic cables in the intertidal environment is capable of rapidly providing near-surface S-wave velocity data across considerable spatial scales (multikilometer) at high resolution, which is beneficial for the design of subsea cables routes and landfall locations. The associated reduction in deployment and survey duration, when compared with conventional approaches, is particularly important when working in the marine environment due to potentially short weather windows and expensive downtime.

Applicability of soil‐type index for shear wave velocity‐based liquefaction assessment

AbstractThe current simplified liquefaction assessment method based on the shear‐wave velocity, Vs has uncertainties about how the fine contents change the Vs‐based liquefaction resistance. According to the simplified method, for a given Vs, the cyclic resistance ratio (CRR) increases with an increase in fine contents. However, field investigations recently revealed that for various silty sands, the correlation between CRR and Vs is soil‐type index dependent and not specific for all sand‐silt mixtures with the same fine contents. Therefore, a detailed experimental research program is performed in this study to clarify the effect of the soil‐type index on the shear wave velocity and CRR correlation. In the first part of the present study, the cyclic resistance of sand mixed with non‐plastic (NP) fines (dry weight of 0%, 5%, 15%, and 35%) was investigated using cyclic direct simple shear (CDSS) tests. Seismic cone penetration (SCPT) tests were performed inside the large‐scale box to facilitate normalized cone penetration resistance (qc1N) and shear wave velocity measurements on the soils used in the CDSS tests. A new correlation was proposed between the qc1N and normalized shear wave velocity (Vs1) using the soil‐type index Ic representing the behavior of soil. Then, CRR‐Vs1 correlation was obtained experimentally for four distinct ranges of soil‐type index. Finally, the results of this study and the proposed CRR‐Vs1 trends in other investigations were used to discuss the soil‐type dependent Vs‐based liquefaction susceptibility zones.

Evaluation of Flow Liquefaction Susceptibility in Non-Plastic Silty Soils Using the Seismic Cone

The state parameter allows the evaluation of the in situ state of soils, which can be particularly useful in tailings impoundments where flow liquefaction is the most common failure model. Positive state parameter values characterize a contractive response during shearing and, for non-plastic soils, can indicate flow liquefaction susceptibility. This paper presents a methodology to classify and estimate the state parameter (Ψ) for non-plastic silty soils based on seismic cone penetration measurements. The method expands on a previous methodology developed for sands that use the ratio of the small strain shear modulus and the cone tip resistance G0/qt for classification and Ψ assessment. For non-plastic silty soils, drainage conditions during cone penetration must be accounted for and are used to allow soil classification and correct the cone tip resistance. An empirical formulation is proposed to correct qt for partial drainage measurements and predict Ψ for non-plastic silty soils. Mining tailings results of in situ and laboratory tests were used to validate the proposed methodology producing promising responses. The Ψ value estimated through the proposed methodology are in the range of those obtained from laboratory tests, indicating an adequate prediction of behavior for non-plastic silty soils.

In-situ material damping measurements using the crosshole seismic method

Crosshole seismic testing is commonly used to determine detailed and reliable wave velocity profiles. Material damping measurements can also be performed in crosshole seismic testing, but these measurements require a window function to maintain similar amplitude shapes over the frequency range of interest for the calculation. In-situ seismic testing, including downhole and seismic cone penetration testing (SCPT), also requires a window function for the material damping calculations. However, the length of the window function has the largest influence on the material damping calculation. Therefore, the half-power bandwidth method is introduced to determine the material damping ratio without the window function in crosshole testing by replicating the unconfined, free-free, resonant column (Fr-Fr) test. To demonstrate the influence in the length of the window function, the first cycle of the signal is used in the material damping calculation. The half- power bandwidth method is verified using synthetic signals and field data. Two sets of crosshole and downhole tests were performed, one at a backfill test pad and the second at a Hornsby Bend research site operated by the University of Texas at Austin. The in-situ material damping ratio calculated from these two sets of crosshole tests using the half-power bandwidth method are compare with the Spectral Ratio Slope (SRS) method applied to the downhole testing at these sites. The material damping calculated from the half-power bandwidth method using the full signal results in a reliable and precise damping value compared to the SRS method applied to the downhole data.

A machine learning framework for in situ sensing of pile length from seismic cone penetrometer data

Several hundred high mast light towers (HMLTs) throughout the state of Minnesota have foundation systems, typically concrete-filed steel pipe piles or steel H-piles, with no construction documentation, e.g., pile lengths. Reviews of designs within current standards suggest that some of these foundations may have insufficient uplift capacity in the event of peak wind loads. Without knowledge of the in situ pile length, an expensive retrofit or replacement program would need to be conducted. Thus, developing a screening tool to determine in situ pile length – as compared to a bulk retrofit of all towers with unknown foundations – would provide significant cost savings. The goal of the project is to establish a non-destructive evaluation (NDE) technique, including the testing setup and data analysis algorithms, for determining in situ pile lengths by way of seismic waves. This work specifically focuses on (i) the use of ground vibration waveforms captured by a seismic cone penetrometer; (ii) three-dimensional visco-elastodynamic finite element method (FEM) used as a tool to relate the sensory data to in situ pile length; and (iii) the use of machine learning (ML) algorithms, trained with the outputs of FEM simulations, to solve the germane inverse problem. In principle, the scarcity of existing HMLT configurations with known pile depth creates an absence of field data needed to adequately train an ML algorithm. However, we demonstrate that the use of FEM simulations as proxy training data for the ML algorithms leads to a robust data interpretation scheme.

Identifying Collapsible Soils from Seismic Cone (SCPT): A Qualitative Approach

Collapsible soils are unsaturated low-density soils that undergo abrupt settlement when flooded without any increase in the in-situ stress level. The first stage of the site characterization is identifying collapsible soils, since these are problematic soils. Seismic cone testing (SCPT) has been increasingly used for site characterization, because it allows combining stratigraphic logging with the maximum shear modulus (G0) determination. In this paper, laboratory and in-situ tests carried out at 21 sites with collapsible and non-collapsible soils are interpreted to differentiate between such soils, based on the seismic cone test (SCPT). Collapsible soils have G0/qc values greater than 23 and qc1 values less than 70, while non-collapsible soils have G0/qc values less than 23 and qc1 values greater than 70. The investigated collapsible soils have microstructure (bonding/cementation), but the classical approach cannot be sufficient to identify collapsible soils alone. An approach was used to identify collapsible soils based on maximum shear modulus (G0), normalized cone resistance (qc1), and cone resistance (qc). The chart G0/qc versus qc1 and boundaries is an alternative for distinguishing between collapsible and non-collapsible soils in the early stage of site investigation. This qualitative approach should be used in the preliminary investigation phase to select potentially collapsible soils and helps guide the sampling of potentially collapsible soils for laboratory testing. Further SCPT data from different soil types, particularly the collapsible ones, are valuable to adjust or confirm the boundary equations suggested.

Field and laboratory measurements of shear wave velocity in unsaturated soils

Shear wave velocity measurements in soil are important for assigning site soil profiles to seismic site classes and for calculating other dynamic soil properties. The seismic cone penetration test (SCPT) is commonly used to determine shear wave velocity profiles in the field. In the laboratory, bender elements provide an easy means to measure shear wave velocity of soil specimens from discrete depths. In this study, shear wave velocity measurements obtained from unsaturated soil profiles in the field and on field samples in the laboratory under similar stress conditions were analyzed and compared. Additionally, the influence of seasonal changes on the behavior of shear wave velocity was investigated. Comparisons of shear wave velocities from the field and laboratory were favorable for similar moisture and stress conditions. However, results showed that as the degree of saturation increases and suction decreases the shear wave velocity can decrease significantly.

Developments in the seismic CPT and links to the Ménard Pressuremeter Test

The seismic cone penetration test (SCPT) was developed in the early 1980s and significant developments have been made in its use and application. This paper provides a review of these developments with particular emphasis on its application to identify soil microstructure. The Ménard pre-bored pressuremeter test (PMT) is one of the most popular in situ tests in France and links between SCPT results and the PMT are suggested.

A database of ground motion recordings, site profiles, and amplification factors from the Groningen gas field in the Netherlands

A comprehensive database that has been used to develop ground motion models for induced earthquakes in the Groningen gas field is provided in a freely accessible online repository. The database includes more than 8500 processed ground motion recordings from 87 earthquakes of local magnitude ML between 1.8 and 3.6, obtained from a large network of surface accelerographs and borehole geophones placed at 50 m depth intervals to a depth of 200 m. The 5%-damped pseudo-acceleration spectra and Fourier amplitude spectra of the records are also provided. Measured shear-wave velocity (VS) profiles, obtained primarily from seismic Cone Penetration Tests (CPTs), are provided for 80 of the ∼100 recording stations. A model representing the regional dynamic soil properties is presented for the entire gas field plus a 5 km onshore buffer zone, specifying lithology, VS, and damping for all layers above the reference baserock horizon located at about 800 m depth. Transfer functions and frequency-dependent amplification factors from the reference rock horizon to the surface for the locations of the recording stations are also included. The database provides a valuable resource for further refinement of induced seismic hazard and risk modeling in Groningen as well as for generic research in site response of thick, soft soil deposits and the characteristics of ground motions from small-magnitude, shallow-focus induced earthquakes.

CPT-Vs correlations for post-glacial sediments in Metropolitan Vancouver

A comprehensive Seismic Cone Penetration Test (SCPT) database for post-glacial sediments in Metro Vancouver is compiled to assess and establish relationships between CPT parameters and shear-wave velocity (Vs). Five world-wide and one existing Fraser River Delta (FRD) specific empirical CPT-Vs correlations are examined and found to have limited applicability in predicting Vs from our SCPT database. Region-specific CPT-VS models are then developed from a training dataset using 4 different regression approaches and 6 different CPT parameters combinations. The regression approaches include multi-linear (MLR) and nonlinear (NLR) regressions, and Random Forest and Extreme Gradient Boosting supervised ensemble machine learning models. The performance of different models and CPT parameters combinations is assessed using a testing dataset. The machine learning models are found to perform slightly better than MLR and NLR models in predicting Vs. Based on performance and practicality, a final CPT-Vs model is selected and applied to predict Vs for 59 compiled CPTs in the region. The comparison between predicted CPT-Vs profiles and measured Vs profiles in similar geology units confirms accuracy of our developed model. The developed CPT-Vs prediction models can be employed to obtain Vs profiles for site response analysis, compare CPT- and Vs-based liquefaction evaluation methods, or map Vs30 in Metro Vancouver.

Verification of Seismic Cone Penetration Test Calibration Chamber Tests on a Sand

Abstract Calibration chambers are experimental apparatuses that allow the physical modeling of an in situ testing method, such as the cone penetration test (CPT), by performing laboratory experiments on soil samples with known stress, strain, and density characteristics. Over a series of development and improvements, more recent calibration chambers and laboratory cone penetrometers have become compact and less laborious than their predecessors. This includes the focus of this study where a miniature cone penetration testing (MCPT) calibration chamber previously designed and used at Western University is upgraded to measure shear wave velocity (VS) and enable anisotropic consolidation of soil specimens using a hydraulic piston. In addition to VS, MCPT can also measure cone tip resistance, sleeve friction, and excess pore water pressure developed behind the cone tip. A full test plan using the newly upgraded MCPT calibration chamber is presented in this study. These tests are performed on Fraser River sand at various relative densities and effective stresses. Results of this testing program are validated by comparison with a series of in situ seismic CPTs in the Fraser River delta, existing correlations between VS and cone tip resistance, and several other calibration chamber tests on different sands. Through these comparisons, the overall viability of the initial MCPT calibration chamber design, modifications made to the MCPT setup, and ultimately the results produced from this device are confirmed.

Influence of source-to-site distance and diagenesis on liquefaction triggering of 200,000-year-old beach sand

Liquefaction triggering of the outcropping 200,000-year-old Ten Mile Hill beds sand facies (Qts) near Charleston, South Carolina is characterized in this paper. The characterization includes evaluating the relative susceptibility to liquefaction of Qts assuming a uniform seismic load and using seismic cone penetration testing at 46 sites, the ratio of measured small-strain shear wave velocity to estimated small-strain shear wave velocity (MEVR), and the liquefaction potential index (LPI). The computed LPI values indicate a slight decrease in the liquefaction susceptibility of Qts moving away (5 to 30 km) from the likely source of the 1886 Charleston earthquake (Mw ~ 7). Also characterized is the liquefaction potential of Qts during the Charleston earthquake and a range of other earthquake loadings. The results for the range of other earthquake loadings are summarized in terms of liquefaction probability curves, which provide a method for mapping liquefaction potential in Qts. A back-calculated, lower-bound diagenesis correction factor of 1.11 for areas of Qts where liquefaction surface manifestations were not observed agrees well with the published data.

Laboratory-scale seismic CPT calibration chamber tests on Fraser River sand

Physical modeling of cone penetration testing (CPT) can be carried out under known stress, deformation, and density conditions using laboratory calibration chambers. This study presents the results of reduced-scale model CPTs (MCPT) on Fraser River sand using a calibration chamber that allows anisotropic consolidation of soil specimens, as well as the measurement of shear wave velocity (VS), using bender elements. In addition to VS, MCPT can also measure cone tip resistance (qc), sleeve friction (fs), and pore water pressure developed behind the cone tip (Δu2). The CPT model tests are performed on Fraser River sand at different effective stresses and relative densities. The CPT calibration chamber test results are comparable with those of in situ seismic cone penetration tests (SCPT) in the Fraser River delta, existing correlations between VSand qc, and calibration chamber tests on other sands. This confirms the overall feasibility of the MCPT calibration chamber design for the measurements of qc, fs, and VSin sandy soils.

In-situ properties of Poisson's ratio based on KiK-net seismic observations

Poisson's ratio has been considered as an important parameter for the analysis of a geotechnical structure under both static and dynamic loads by many researchers. However, most of the studies have been performed using laboratory test such as resonant column and bender element, or the field test without seismic data such as suspension logging, seismic cross-hole and seismic cone penetration, the studies using the geophysical method based on seismic observations are rare. In this study, in-situ properties of Poisson's ratio are investigated based on KiK-net seismic data. The methods for extracting the in-situ Poisson's ratio and describing its variation with shear strain considering effect of groundwater are firstly introduced. Then, an empirical model for the in-situ assessment of small-strain Poisson's ratio is proposed based on the studies of the effects of vertical effective stress, groundwater and rock layer type. Moreover, it is found that the change threshold of the in-situ Poisson's ratio is larger than the laboratory test results. The results of the study are verified in part based on the fact that they are generally consistent with the theoretical and experimental relationships in many ways, and they can be employed as the reference to the engineering practice and related studies, such as site response analysis and specifying material constitutive relationships for the numerical analysis.

Modified refracted ray path method for determination of shear wave velocity profiles using seismic cone

The commonly used data reduction methods to determine shear wave velocity (Vs) require the depth interval of the Vs profile to be the same as the in-situ testing interval. The Vs values derived in this way are the mean values within the depth intervals. However, the in-situ multilayer interfaces do not always coincide with the predetermined testing depths, and the materials may change dramatically across layers and thus the above interpretation methods may not always produce representative soil properties. In this study, a modified refracted ray path method for more flexible Vs calculation is proposed. The method takes advantage of the routine cone penetration testing data obtained in SCPT tests and applies a combined approach for the soil layer identification using both the corrected cone tip resistance (qt) and the Soil Behavior Type Index (Ic) as indicators. Vs is then calculated using the Snell's law based on the original shear wave travel times and the newly identified layer profiles. The proposed method can avoid the error caused by crossing the multilayer boundaries and provide a more accurate prediction of soil type and the corresponding stiffness properties. The data show that by using the proposed method, the accuracy of the estimated Vs can be improved by up to 77% for a soil layer with interface not located at testing depths, as compared to Vs obtained from the conventional methods.

Assessment of small-strain characteristics for vibration predictions in a Swedish clay deposit

Environmental vibrations induced by human activities such as traffic, construction or industrial manufacturing can cause disturbance among residents or to vibration sensitive equipment in buildings. In Sweden, geological formations of soft clay overlying a stiff bedrock are soil conditions prone to ground vibrations that are encountered both in urban areas and along parts of the national railway network. This paper presents an extensive investigation of the small-strain soil properties for the prediction of environmental ground vibrations in a shallow clay where the bedrock is situated at 7.5 m depth. The small-strain properties are estimated using available empirical correlations, bender elements, seismic cone penetration tests, seismic refraction and inversion of surface wave dispersion and attenuation curves. The results are synthesised into a dynamic layered soil model which is validated by measurements at the soil's surface at source-receiver distances up to 90 m in the frequency range 1–80 Hz. Analyses of uncertainties in the estimated values of wave speeds and material damping are performed by model investigations, indicating that surface wave tests overestimate the damping compared to bender element tests. The properties of the topmost unsaturated part of the soil is found to have a significant influence on the response at large distances, caused by critically refracted P-waves resonating in the top layer.