Shear Wave Velocity Measurements Research Articles

The failure type-dependent characterization of liquefaction resistance by small-strain shear modulus for saturated sand

In this study, a re-visit of existing laboratory tests was carried out to study the relationship between the liquefaction resistance (CRR) and the small-strain shear modulus (Gmax) of saturated sands with consideration of the failure types of both cyclic mobility and flow liquefaction. The result indicates that the relationship between CRR and Gmax is failure type-dependent, and the liquefaction resistance of cyclic mobility grows faster than that of flow liquefaction. Then discrete element method was used to explore the relationship between the liquefaction resistance and the small-strain shear modulus for a typical saturated granular material, with consideration of different liquefaction types. A series of undrained stress-controlled cyclic tests together with shear wave velocity measurements were simulated, and results similar to the laboratory studies were obtained. Then a new expression is proposed to describe the relationship between CRR and Gmax for granular material. The corresponding micromechanical mechanism is further explored, which shows that there are two kinds of distinct behaviors of the particle contact structure when the granular material changes from loose to dense state under the same confining stress. Compression behavior is dominant for flow liquefaction while collapse behavior is dominant for cyclic mobility type of liquefaction. The different behaviors of the particle contact structure influence the growth of the mechanical contacts, which further leads to the failure type-dependent growth of liquefaction resistance for a saturated granular material.

Quantitative measurements of radiation-induced fibrosis for head and neck cancer: A narrative review.

To provide a comprehensive summary of the different modalities available to measure soft tissue fibrosis after radiotherapy in head and neck cancer patients. PubMed, Scopus, and Web of Sciences. A search was conducted using a list of medical subject headings and terms related to head and neck oncology, radiation fibrosis, and quantitative measurements, including bioimpedance, MRI, and ultrasound. Original research related to quantitative measurement of neck fibrosis post-radiotherapy was included without time constraints, while reviews, case reports, non-English texts, and inaccessible studies were excluded. Discrepancies during the review were resolved by discussing with the senior author until consensus was reached. A total of 284 articles were identified and underwent title and abstract screening. Seventeen articles had met our criteria for full-text review based on relevance, of which nine had met our inclusion criteria. Young's modulus (YM) and viscoelasticity measures have demonstrated efficacy in quantifying neck fibrosis, with fibrotic tissues displaying significantly higher YM values and altered viscoelastic properties such as increased stiffness rate-sensitivity and prolonged stress-relaxation post-radiation. Intravoxel incoherent motion offers detailed insights into tissue changes by assessing the diffusion of water molecules and blood perfusion, thereby differentiating fibrosed from healthy tissues. Shear wave elastography has proven to be an effective technique for quantifying radiation-induced fibrosis in the head and neck region by measuring shear wave velocity. There are various modalities to measure radiation-induced fibrosis, each with its unique strengths and limitations. Providers should be aware of these implications and decide on methodologies based on their specific clinical workflow. Step 5.

An improved characterization model of liquefaction resistance by shear wave velocity for binary mixtures with consideration of coarse content

This paper aims to develop an improved CRR-Vs1 characterization model for soil liquefaction evaluation for binary mixtures via a series of DEM simulations of drained monotonic tests, undrained cyclic tests and shear wave velocity measurements. The contributions of different contact types to the mean effective stress of binary mixtures depend mainly on the coarse content and to a negligible extent on the confining pressure and particle size ratio. The threshold coarse content, denoting the mechanical behavior transition of binary mixtures, can be identified either by the macroscopic evolutions of critical state lines or the distributions of microscopic contact forces. The skeleton reinforcement factor m decreases approximately linearly with the increase of coarse content, while the skeleton supporting factor b exhibits a nonlinear decrease relationship with coarse content, both of which are influenced by particle size ratio. Under the condition of the same equivalent skeleton void ratio, a Vs-correction function and a CRR-correction function are introduced to consistently describe the nonlinear coarse content effects on the shear wave velocities and liquefaction resistances of binary mixtures. The improved CRR-Vs1 characterization model with consideration of coarse content is established by relating the shear wave velocity and liquefaction resistance of binary mixtures to those of the base fine or coarse matrix using the concept of equivalent skeleton void ratio. Application of the proposed characterization model to real geotechnical materials requires laboratory element tests to determine the Vs-correction function and the CRR-correction function, together with the CRR-Vs1 benchmark curve of the base fine or coarse matrix.

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.

Regional seismic velocity model for the U.S. Atlantic and Gulf Coastal Plains based on measured shear wave velocity, sediment thickness, and surface geology

The Atlantic and Gulf Coastal Plains (CPs) are characterized by widespread accumulations of low-velocity sediments and sedimentary rock that overlay high-velocity bedrock. Geology and sediment thickness greatly influence seismic wave propagation, but current regional ground motion amplification and seismic hazard models include limited characterization of these site conditions. In this study, a new regional seismic velocity model for the CPs is created by integrating shear wave velocity (VS) measurements, surface geology, and a sediment thickness model recently developed for the CPs. A reference rock VS of 3000 m/s has been assumed at the bottom of the sedimentary columns, which corresponds to the base of Cretaceous and Mesozoic sediments underlying the Atlantic CP and the Gulf CP, respectively. Measured VS profiles located throughout the CPs are sorted into five geologic groups of varying age, and median VS profiles are developed for each group by combining measured VS values within layer thicknesses defined by an assumed layering ratio. Statistical analyses are also conducted to test the appropriateness of the selected groups. A power law model with geology-informed coefficients is used to extend the median velocity models beyond the depths where measured data were available. The median VS profiles provide reasonable agreement with other generic models applicable for the region, but they also incorporate new information that enables more advanced characterizations of site response at regional scales and their effective incorporation into seismic hazard models and building codes. The proposed median velocity profiles can be assigned within a grid-based model of the CPs according to the spatial distribution of geologic units at the surface.

Using ultrasound shear wave elastography to characterize peripheral nerve mechanics: a systematic review on the normative reference values in healthy individuals.

Ultrasound shear wave elastography (SWE) is an emerging non-invasive imaging technique for peripheral nerve evaluation. Shear wave velocity (SWV), a surrogate measure of stiffness, holds promise as a biomarker for various peripheral nerve disorders. However, to maximize its clinical and biomechanical value, it is important to fully understand the factors that influence nerve SWV measurements. This systematic review aimed to identify the normal range of SWV for healthy sciatic and tibial nerves and to reveal the factors potentially affecting nerve SWV. An electronic search yielded 17 studies eligible for inclusion, involving 548 healthy individuals (age range, 17 to 72 years). Despite very good reliability metrics, the reported SWV values differed considerably across studies for the sciatic (1.9-9.9 m/s) and tibial (2.3-9.1 m/s) nerves. Factors such as measurement proximity to joint regions, limb postures inducing nerve axial stretching, and transducer alignment with nerve fiber orientation were associated with increased SWV. These findings suggest regional-specific nerve mechanical properties, non-linear elastic behaviour, and marked mechanical anisotropy. The impact of age and sex remains unclear and warrants further investigation. These results emphasize the importance of considering these factors when assessing and interpreting nerve SWE. While increased SWV has been linked to pathological changes affecting nerve tissue mechanics, the significant variability observed in healthy nerves highlights the need for standardized SWE assessment protocols. Developing guidelines for enhanced clinical utility and achieving a comprehensive understanding of the factors that influence nerve SWE assessments are critical in advancing the field.

Practical use of shear wave velocity measurements in UK clays (BGA Touring Lecture 2023)

This paper seeks to promote use of shear wave velocity (Vs) measurements in UK clays as a complement to more standard ground investigation techniques. Vs measurements seem to be repeatable and independent of the method of measurement used in isotropic soil conditions – for example, soft clays. However, in glacial tills, and especially in the overconsolidated clays of south-east UK, Vs measurements will differ depending on the direction of propagation and polarisation of the shear waves due to natural stress anisotropy and the fissured nature of the materials. Correlations between Vs and other in situ data and with a variety of soil properties can be very powerful and some have been proposed here for UK clays. However, these correlations should ideally be local and only applied to other soils and areas with great caution. Other uses of the techniques, beyond those of classical dynamic analyses, have been described together with some future challenges. Uncertainties in the methods have been well researched and several methods have been proposed to deal with these uncertainties. Nonetheless, advice from a geophysical colleague will enhance the geotechnical engineers’ use of Vs data.

Characterization of an organic soil deposit using multi-faceted geotechnical field and laboratory investigations

The findings from a comprehensive characterization of an organic soil deposit using multi-faceted geotechnical field and laboratory investigations are presented. The field-testing program comprised cone penetration testing (SCPT) with shear wave velocity (Vs) measurements, full-flow ball penetration testing (BPT), and electric vane shear testing (eVST). The work was supplemented by a laboratory program comprising index testing, one-dimensional consolidation testing, and direct shear testing conducted on the tube and disturbed soil samples obtained from the site. Data originating from this wide range of testing tools deployed at a single site provided a unique opportunity to get insights into the strength and stiffness properties of organic soils and examine possible correlations between such properties and test measurements. The work confirmed the suitability of BPT for characterizing organic soils due to its ability to mobilize/test a larger representative volume of soils during penetration, thereby reflecting a practical average response for the tested soil mass. It was possible to develop simple correlations to directly estimate the small-strain stiffness (Gmax) and undrained shear strength (Su) of organic soils using data from BPT. With these capabilities, combined with the simplicity and the relatively easy field deploy ability, BPT emerges as a tool with high applicability for the geotechnical characterization of organic soils - an activity essential to support the design of buried energy pipelines that traverse over large distances in remote muskeg terrains in Canada.

Martian Crustal Model From a Joint Inversion of Receiver Functions and Apparent Shear Wave Velocity

AbstractReceiver function (RF) based studies have revealed the layered Martian crustal structure beneath the InSight, which provides key information about the composition, rock alteration, deep magma process, and thermal history of Mars. However, limited by the frequency and trade‐offs between the thickness and velocity, inverting RFs alone is difficult to provide an accurate image of the upper crust. Here, by achieving stable measurements of the apparent shear wave velocities (Vs,app) at different frequencies for high‐quality marsquakes, we perform a joint inversion with the RFs. Our crustal models differ from previous models by having an extra shallow structure in the upper crust, either a layer with a sharp velocity jump interface at 4.0 ± 0.9 km depth or a gradient structure with shear wave velocity increasing gradually from 1.1 ± 0.1 km/s near the surface to 1.7 ± 0.3 km/s at a depth of 6.0 ± 2.4 km, which well fits both RFs and Vs,app's. Such an upper crustal velocity model is consistent with the depth‐decaying of porosity due to self‐compaction and indicates a highly porous upper crust with a surface porosity larger than 30%. Besides, a much higher porosity decay constant than that scaled from the Moon is derived, suggesting different mechanical properties of the lunar and Martian crust.

Detecting advanced liver fibrosis using ultrasound shear wave velocity measurement in the general population.

Advanced fibrosis detection in the general population is an unmet need. Additionally, screening method for advanced fibrosis in the general population is not established. Thus, this study aimed to examine the use of shear wave measurement (SWM), which measures liver stiffness by ultrasound elastography as a screening tool for advanced fibrosis in health checkups that represents the general population. SWM was performed in all subjects. Magnetic resonance elastography (MRE) was performed in those with SWM shear wave velocity (Vs) ≥1.3 m/s to determinate advanced fibrosis. The diagnostic accuracy of SWM Vs for advanced fibrosis (determined by MRE of ≥3.62 kPa) was examined. This prospective study was registered with the University Hospital Medical Information Network clinical trial registry (UMIN000041609). A total of 2,233 subjects were included. SWM Vs of 1.64 m/s was selected as the best threshold for advanced fibrosis. Using the threshold of SWM Vs at ≥1.64 m/s, subjects were narrowed down to 1.7%, and sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for advanced fibrosis were 53.3%, 92.4%, 47.1%, and 94.0%, respectively, among these subjects. The multivariable analysis, after adjusting the age, sex, body mass index (BMI), hypertension, diabetes mellitus (DM), dyslipidemia, and alcohol use, revealed an SWM Vs of ≥1.64 m/s as the significant factor for advanced fibrosis with an odds ratio (95% confidence interval) of 14.5 (3.4-62; P<0.001). SWM has high diagnostic accuracy for advanced fibrosis (PPV 47.1%) and may be used as a screening tool for liver fibrosis in the general population.

Seismic and Liquefaction Hazard Maps for Five Western Tennessee Counties

Abstract A five-year seismic and liquefaction hazard mapping project for five western Tennessee counties began in 2017 and supported natural hazard mitigation efforts in Lake, Dyer, Lauderdale, Tipton, and Madison counties. Additional geological, geotechnical, and geophysical information has been gathered in all five counties to improve the base northern Mississippi Embayment hazard maps of Dhar and Cramer (2017). Information gathered includes additional geological and geotechnical subsurface exploration logs, water table level data collection, new measurements of shallow shear-wave velocity (VS) profiles, and the compilation of existing VS profiles in and around the counties. Improvements have been made in the 3D geological model, water table model, the geotechnical liquefaction probability curves, and the VS correlation with lithology model for these counties. The resulting updated soil response amplification distributions on a 0.5 km grid were combined with the 2014 U.S. Geological Survey seismic hazard model (Petersen et al., 2014) earthquake sources and attenuation models to add the effect of local geology for Lake, Dyer, Lauderdale, Tipton, and Madison Counties. The resulting products are similar to the Memphis and Shelby County urban seismic hazard maps recently updated by Cramer, Dhar, and Arellano (2018). Generally, the effect of local geology is to reduce seismic hazard at short periods and increase it at long periods. Liquefaction hazard is high only in the alluvial lowlands, but not in the loess covered uplands.

Use of shear wave velocity for assessing engineering properties of compacted bentonite after swelling

The characteristics of compacted bentonite after swelling determine the long-term stability of barrier systems. Due to the fact that the current stress level is the most important variable in determining the performance of engineered geosystems, this study aims to investigate the stress states and the consequent change in engineering properties of compacted bentonites after swelling. A series of vertical and horizontal swelling pressure tests were performed for compacted bentonites with varying initial dry unit weights at varying pore fluid concentrations. The compacted bentonite samples after swelling were loaded to investigate the changes in lateral stress and deformability. In addition, the shear wave velocity was continuously measured during and after swelling processes. The results of this study demonstrate that the swelling pressure increased with increasing dry unit weight of tested materials and decreasing pore fluid concentrations. The changes in lateral stress and void ratio of compacted bentonite after swelling were only measurable when the applied vertical stress was greater than the swelling pressure, reflecting that the swelling pressure cancels out the externally applied stress. Most notably, this study reveals that the initiation and termination of the swelling process and the change in engineering properties of compacted bentonite after swelling can be determined by measuring shear wave velocity.

Bender-element-based penetrometers for measuring shear wave velocity and shear strength

A bender-element-based dynamic penetrometer (BE-DP) was developed for the measurement of shear wave velocity (Vs-hh and Vs-hv) and shear strength parameters (cohesive strength (c) and internal friction angle (ϕ)) of soils. Shear wave velocity was measured through two pairs of bender elements installed in the cone shafts. Small-strain stiffness (Ghh and Ghv) and stiffness anisotropic ratio (Ghh/Ghv) were calculated through the measured shear wave velocity. Shear strength parameters were obtained through a series of theoretical formulas. In-situ tests of fully weathered slate (FWS) and granite residual soil (GRS) by applying BE-DP indicated that FWS had obvious stiffness anisotropy while GRS had slight stiffness anisotropy, which were in consistent with SEM and TEM observations of two kinds of soils. Meanwhile, SEM and TEM observations also showed that soil particle size of FWS was much larger than that of GRS, resulting in a much larger shear wave velocity and small-strain stiffness of FWS than GRS. Due to less disturbance of in-situ tests than laboratory experiments, shear strength measured by BE-DP was a little bit larger than that measured by laboratory experiments for both FWS and GRS. In-situ test results proved that the newly developed BE-DP was feasible, robust, multifunctional and cost-effective.

Static Liquefaction Assessment Combining Shear Wave Velocity, Peak Strength and Soil Grading

A large set of undrained compression triaxial tests was carried out on different types of cohesionless soils, from sands to silty sands and silts. Shear wave velocity measurements were also carried out. These tests exhibit distinct state transitions ranging from flow liquefaction to strain softening or strain hardening. With the purpose of defining a framework to assess soil liquefaction, it was found that the ratio between the shear wave velocity (VS0) and the peak undrained deviatoric stress (qpeak), VS0/qpeak, could be accurately used to define a boundary between liquefaction and strain hardening for sands and between strain softening and strain hardening for silty sands and silts. Since this ratio is a function of the tested material, the prediction of these boundaries can be made as a function of soil grading, namely via the coefficient of uniformity, CU. Despite not being regarded as a strong geomechanical parameter, CU is easily determined from a grain-size distribution test and has an empirically proven correlation with critical state parameters.

Airfield suitability assessment from geophysical methods

The construction of new airfields on semi-prepared terrain and the repair of existing airfield requires a quick and accurate suitability assessment of the subgrade soil strength and stability. The suitability of an airfield for regular operations is a function of the stiffness of the subgrade soil under small deflections. Stiffness is characterized by the elastic modulus of the soil. In-situ soil modulus values are commonly estimated from California Bearing Ratio (CBR) values via an empirical relationship. Currently, the dynamic cone penetration (DCP) testing method is the most widely used technique for determining the in-situ CBR. For airfield design, a DCP value is used to estimate a CBR value, which in turn, is used to estimate a modulus value. When these individual empirical equations are combined, the errors inherent to each empirical equation are compounded. Geophysical measurements such as seismic wave velocity and electrical resistivity can directly quantify modulus and eliminate a need for a multistep empirical process.This paper presents the results of an effort to use seismic wave velocity and electrical resistivity data to determine airfield design parameters. For the reported study, CBR values estimated from DCP penetration resistance were compared to equivalent CBR values estimated from shear wave velocity and electrical resistivity values. Relationships linking the geophysical measurements to CBR estimates were established using laboratory data. These relationships were then applied to field in-situ measurements. The field in-situ measurements were further used to calculate airfield design parameters such as allowable aircraft load and the number of aircraft passes. The results of this study show that CBR values estimated from shear wave velocity measurements well matched DCP-derived CBR values. Thus, establishing the viability of utilizing geophysical methods to assess airfield suitability.

Ultrasound Shear Wave Elastography Quantitatively Assesses Tension Changes of Supraspinous/Interspinous Ligament Complex Under Varied Loads.

Although interspinous and supraspinous ligaments of the lumbar spine are thought to contribute to spinal stability, little is known about their dynamic biomechanics. We demonstrate that shear wave elastography (SWE) offers a novel technique to noninvasively and quantitatively evaluate posterior spinous ligament complex functional loading and stiffness in different physiologic positions. We performed SWE and measured the length of the interspinous/supraspinous ligament complex in cadaveric torsos (N = 5), isolated ligaments (N = 10), and healthy volunteers (N = 9) to obtain length and shear wave velocity measurements. For cadavers and volunteers, SWE was utilized in 2 lumbar positions: lumbar spine flexion and extension. In addition, SWE was performed on isolated ligaments undergoing uniaxial tension to correlate shear wave velocities with experienced load. Average shear wave velocity in cadaveric supraspinous/interspinous ligament complexes increased for lumbar levels (23%-43%) and most thoracic levels (0%-50%). This corresponded to an average increase in interspinous distance from extension to flexion for the lumbar spine (19%-63%) and thoracic spine (3%-8%). Volunteer spines also demonstrated an average increase in shear wave velocity from extension to flexion for both the lumbar spine (195% at L2-L3 to 200% at L4-L5) and thoracic spine (31% at T10-T11). There was an average increase in interspinous distance from extension to flexion for the lumbar spine (93% at L2-L3 to 127% at L4-L5) and thoracic spine (11% at T10-T11). In isolated ligaments, there was a positive correlation between applied tensile load and average shear wave velocity. This study creates a foundation to apply SWE as a noninvasive tool for assessing the mechanical stiffness of posterior ligamentous structures and has potential applications in augmenting or evaluating these ligaments in patients with spine pathology. The interspinous and supraspinous ligaments are critical soft tissue supports of the posterior lumbar spine. Disruption of these structures is thought to have a negative impact on spinal stability in trauma and spine deformities.

Evaluation of skeletal muscle elasticity using color Doppler shear wave imaging

PurposeThis study aimed to (1) assess the precision and reproducibility of color Doppler shear wave imaging (CD SWI) by comparing it with shear wave elastography (SWE) via elasticity phantom measurements, and (2) investigate the potential clinical applications of CD SWI in the upper limb muscles by assessing the reproducibility of skeletal muscle elasticity evaluations.MethodsFour elastography phantoms of different stiffness (6.0–7.5 wt%) were used to assess the precision and reproducibility of CD SWI (compared with SWE) at depths. Typical upper limb muscles of 24 men were also assessed for this comparison.ResultsAt superficial depths (0–2 cm), the phantom measurements obtained using CD SWI and SWE were similar at all levels of stiffness. Furthermore, both methods were highly reliable, with almost perfect intra- and inter-operator reliabilities. At greater depths (2–4 cm), measurements obtained using both methods were similar at all stiffness levels. Although standard deviations (SDs) of the phantom measurements obtained using both methods at lower stiffness were similar, those at higher stiffness were different. The SD of the CD SWI measurements was < 50% of that of the SWE measurements. However, both methods were highly reliable in the phantom test, with almost perfect intra- and inter-operator reliabilities. The intra- and inter-operator reliabilities of the shear wave velocity measurements for typical muscles of the upper limbs were also substantial in clinical settings.ConclusionCD SWI is a valid method for measuring elasticity, with precision and reliability as high as those of SWE.Graphical abstract

Assessing the liquefaction potential of seabed soils based on ocean ambient noise in the Yellow River Delta

Seabed soils can undergo liquefaction under cyclic loading, resulting in a rapid decrease in strength and stiffness, which may lead to the destruction of offshore structures. Therefore, the assessment of seabed soil liquefaction will become an important factor in disaster prevention and risk analysis in coastal and offshore engineering construction. In this study, the ocean ambient noise with low-frequency, long-wavelength, and wide-band characteristics was used to conduct and analysis noise based on the horizontal-to-vertical spectral ratio method. The shear wave velocity of the seabed soil was obtained by inverting the ocean ambient noise dataset. Then, we proposed a shear wave velocity threshold that can be used for liquefaction assessment of Holocene unconsolidated fine-grained soils by statistical analysis, and the liquefaction potential of the soils was evaluated according to 1-D shear wave velocity structures and 2-D shear wave velocity profiles. The results showed that the distribution of the shear wave velocity obtained by inverting ocean ambient noise was generally consistent with the measured shear wave velocity in the field, indicating that the inversion results have a certain degree of accuracy. A shear wave velocity threshold of 200 m/s was proposed for liquefaction assessment, determining that the soils within 0-10 m depth in the coastal area of Yellow River Delta have liquefaction potential. This result is in accordance with the assessment based on the critical shear wave velocity, indicating that this threshold is applicable to the assessment of seabed soil liquefaction in the Yellow River Delta. The in-situ observations of ocean ambient noise provide a more convenient, economical, and environmentally friendly method, which can help to investigate marine geology disasters and serve marine engineering construction.

Model uncertainties of SPT, CPT, and VS-based simplified methods for soil liquefaction assessment

Simplified methods for assessing soil liquefaction potential based on the standard penetration test (SPT) are prevalent in practice and widely accepted by several seismic design codes. When encountering sites that have not been investigated using SPT, such as offshore sites or sites with a high level of gravel content, engineers can only substitute the methods based on piezocone penetration test data (CPT-qc methods) or shear wave velocity measurements (VS-based methods); however, these two approaches perform inconsistently with methods based on SPT data (SPT-N methods). As a result, this paper exploits the datasets consisting of SPT, CPTU, and in situ seismic test measurements from 13 alluvium sites in the Taipei Basin to compare the performance of prevalent SPT-N, CPT-qc, and VS-based methods. The discrepancies (uncertainties) of these methods are characterized as Gaussian distribution models, which is believed to be a feasible strategy for predicting equivalent results for SPT-N methods when SPT data are not available. Finally, the application of the proposed models to liquefaction potential index evaluation is demonstrated using a real case study.

Predicting the chemotherapeutic response of colorectal cancer liver metastasis using shear-wave elastography.

The aim of this study was to assess the role of the shear-wave velocity (SWV) value in predicting chemotherapeutic response and progression-free survival (PFS) in patients with colorectal cancer liver metastasis (CRLM). In this prospective single-center study, participants with CRLM scheduled for chemotherapy were enrolled between May 2018 and June 2021. SWV measurements were obtained using shear-wave elastography at the CRLM site before and after initiating chemotherapy. Based on the Response Evaluation Criteria in Solid Tumors, the participants were categorized by chemotherapeutic response into responders (complete remission and partial remission) and non-responders (stable disease and progressive disease). Receiver operating characteristic (ROC) curve analysis was conducted to evaluate the performance of changes in SWV measurements in predicting the chemotherapeutic response of CRLM. In addition, a Cox proportional hazards model was used to identify variables associated with PFS. In total, 67 participants (40 men; mean age, 62.3±10.1 years) were enrolled, including 34 responders and 33 non-responders. The area under the ROC curve, sensitivity, and negative predictive value of the SWV measurement in predicting non-responders were 0.840, 97.0%, and 95.2%, respectively, using a cutoff value of a 13% decrease. Additionally, a change in SWV values was independently associated with PFS (hazard ratio, 1.020), non-responder status, and the presence of five or more CRLMs. A change in SWV values measured after chemotherapy demonstrated meaningful diagnostic performance in predicting non-responsiveness among patients with CRLM. Additionally, a change in SWV values was independently associated with PFS.