Pressuremeter Tests Research Articles

Study of the Correlation between Menard Pressuremeter Modulus and Peak Dynamic Resistance Obtained by the Super Heavy Dynamic Cone Penetrometer of Sands of Lome in Togo

The bearing capacity of soils is obtained in various ways using in situ tests, especially pressuremeter and penetrometer tests which are in fact frequently used for the design of foundations. The pressuremeter provides detailed information on the resistance and deformability characteristics of soils at depth. The dynamic cone penetrometer test, on the other hand, is simpler to produce and used to assess the dynamic resistance of the soil, i.e. its behavior under dynamic loads. This study establishes correlations between the dynamic resistance qd of the soil obtained with the super heavy dynamic cone penetrometer and the pressuremeter modulus EM measured with the Menard pressuremeter. The data used in this analysis are those obtained during geotechnical investigations on sands in Lome in Togo and which combined on the same site the super heavy dynamic cone penetrometer test and the Menard pressuremeter test. It appears that for the sands studied, the EM/qd ratio can be bounded as follows: 0.60 ≤ EM/qd ≤ 0.92. Keywords: Correlation, pressuremeter modulus, dynamic resistance, sand.

Rate effects of cylindrical cavity expansion in fine-grained soil

Soil responds to cavity expansion is inherently rate-dependent, especially in the case of fine-grained soils. To better understand such rate effects, self-boring pressuremeter tests were conducted on Kunming peaty soil within a strain rate range of 0.1%/min to 5.0%/min. The results showed a clear dependence of cavity pressure and excess pore pressure (EPP) on strain rates—both increased with higher rates for a given radial displacement. In light of the experimental results, three cases of cylindrical cavity expansion were investigated using the finite element method and analytical method, partially drained expansion in Modified Cam-Clay (MCC) soil, and undrained and partially drained expansion in elastoviscoplastic (EVP) soil. The EVP behavior was and modeled using the MCC model and the overstress viscoplastic theory. The results indicated that over the strain rate range of 0.0001%/min and 50%/min, the rate response of cavity pressure for the case of partially drained expansion in MCC soil (permeability coefficient ranging from 5×10-6 m/s to 2.5×10-11 m/s) is not obvious, while the EPP response during undrained expansion in EVP soil shows rate-independent. Only the partially drained solution for cavity expansion in EVP soil captured the rate-sensitive responses of both cavity pressure and EPP, confirmed by the pressuremeter tests on the Kunming peaty soil, Saint-Herblain clay, and Burswood clay. This suggests that the rate effect results from a combination of drainage-related and time-dependent soil behavior. Parametric studies further demonstrated that both viscous behavior and the overconsolidation ratio significantly influence cylindrical cavity expansion response, and the drainage conditions during expansion can be assessed using a nondimensional velocity.

Cylindrical cavity expansion-contraction solutions in undrained MCC soils with the auxiliary variable approach

Cylindrical cavity exhibits non-self-similarity during contraction process following expansion. Previous studies solve this problem with total strain approach and simple constitutive models, but the approach is not applicable when using an advanced constitutive model. This paper presents a semi-analytical solution for a cylindrical cavity undergoing expansion-contraction in undrained soils with auxiliary variable approach, incorporating the Modified Cam-Clay (MCC) model. The stress states around the cavity are formed by the superposition of initial and superimposed stress states. By treating superimposed effective stresses as self-similar, a semi-analytical solution is derived for solving the cavity expansion-contraction problem. The elastoplastic stress-strain relationship is formulated as a set of first-order differential equations, which can be solved as an initial value problem though Runge-Kutta (RK) method. Then the stress distribution around the cavity during expansion-contraction process can be determined. To validate the proposed approach, a series of well-conduced self-boring pressuremeter (SBP) tests are used to verify the proposed approach, which shows good agreements. Additionally, a FEM simulation incorporating the MCC model is performed, and the simulation results are presented to carry out parametric studies on soil parameters. A significant influence on the range of the plastic and reverse plastic zones is shown for overconsolidation ratio, while the in-situ coefficient of the earth pressure only quantitatively affects the stress distribution.

A multi-target ligand (JM-20) prevents morphine-induced hyperalgesia in naïve and neuropathic rats

The present study examines the possible inhibitory effect of JM-20, a multi-target neuroprotective compound, on the development of morphine-induced hyperalgesia in Male Sprague-Dawley naïve rats. Additionally, the impact of JM-20 on chronic constriction injury (CCI) rats under chronic morphine exposure was investigated, and its efficacy in reducing mechanical hypersensitivity and histopathological changes in the sciatic nerve was assessed. JM-20 (20 mg/kg, per os [p.o.]), administered 60 min before morphine (10 mg/kg, s.c. twice daily at 12 h intervals) for ten days, significantly inhibited the development of morphine-induced hyperalgesia assessed using an electronic pressure-meter paw test, hot-plate, and formalin test, as well as the appearance of spontaneous withdrawal somatic symptoms in rats. Furthermore, JM-20 decreases spinal pro-inflammatory interleukin-1β and restores glutathione to close physiological concentrations, biomarkers directly related to the intensity of mechanical hypernociception. After CCI and sham surgery, co-treatment with JM-20 (10 mg/kg, p.o.) for five days decreased morphine increased-mechanical hypersensitivity, even 12 days after its discontinuation. Continued morphine treatment imposed a neuroinflammatory challenge in CCI animals, further increasing cellularity (>75% immune cell infiltration) with lymphocytes and macrophages. However, JM-20 co-treatment still reduced the presence of cellular infiltrates (51–75%) with a predominance of lymphocytes. Even in the absence of nerve injury, JM-20 attenuated the peripheral neuroinflammatory response observed in morphine-treated sham-operated animals (0% vs. 1–25%). These findings suggest that JM-20 could prevent morphine-induced hyperalgesia by anti-inflammatory and antioxidant mechanisms.

Drained Cavity Expansion–Contraction in CASM and Its Application for Pressuremeter Tests in Sands

Drained Cavity Expansion–Contraction in CASM and Its Application for Pressuremeter Tests in Sands

Prediction and interpretation of limit pressure of clayey soils using ensemble machine learning methods and shapely additive explanations

The pressuremeter test (PMT), a valuable geotechnical in situ test, is used to design foundations of varying depths (shallow, semi-deep, and deep). It assesses a soil's bearing capacity and settlement through two key parameters: limit pressure and pressuremeter modulus. However, the high cost and time demands of PMTs limit their widespread use. This study addresses this challenge by exploring the effectiveness of ensemble machine learning algorithms. To achieve this main goal, we employ two methods, Extreme Gradient Boosting (XGBoost) and Random Forest, to predict limit pressure of soil. To develop the mentioned models an experimental database was used to train and validate the developed models. The effectiveness of these methods are evaluated using three statistical metrics: Mean Absolute Error (MAE), Root Mean Square Error (RMSE), and Coefficient of Determination (R²). The performance metrics show that the developed XGBoost and Random Forest models are viable alternatives to the pressure meter test for estimating limit pressure. Both models achieved high R-squared values (around 0.99 for training and 0.90 for testing) and a low root mean squared error (RMSE) of 3.23 and 4.13 for the testing set, respectively. These results demonstrate the effectiveness of using machine learning in the geotechnical field. To further understand the influence of individual factors on the predictions, we will utilize the Shapley Additive explanations (SHAP) method. This technique analyzes the contribution of each input variable (feature) to the model's predictions of limit pressure. By quantifying the importance of these features; SHAP provides valuable insights into which soil properties most significantly affect the foundation design parameters.

Assessment of Anisotropic Elastic Parameters Using Laboratory Triaxial and In-Situ Pressuremeter Tests in Opalinus Clay

AbstractOpalinus Clay is a stratified shale that exhibits anisotropic deformation properties. In this work, the transversely isotropic deformation parameters of Opalinus Clay are summarized from recent undrained triaxial test campaigns. Relatively consistent values are found for Poisson’s ratios representing different orientations, regardless of the lithofacies and the effective confining stresses used in the tests. Pressuremeter tests were performed at the Mont Terri Rock Laboratory in two boreholes perpendicular and parallel to bedding, respectively. The elastic moduli normal to the borehole wall (borehole moduli) are determined using unloading data obtained at multiple diametric caliper axes and exhibit strong anisotropy for the tests in the borehole parallel to bedding. The anisotropic borehole moduli are predicted based on Amadei and Savage’s (Int J Rock Mech Min Sci 28:383–396, 1991. https://doi.org/10.1016/0148-9062(91)90077-Y) analytical solution using the laboratory-derived Poisson’s ratios and the shear modulus derived from pressuremeter tests in the borehole perpendicular to bedding. The prediction overestimates the magnitude of the borehole moduli but underestimates their anisotropic ratio compared to that from pressuremeter measurement. Drilling a borehole parallel to the bedding of Opalinus Clay is known to induce a local borehole damage zone preferentially developed normal to bedding. The results from a finite element analysis that incorporates this local damage are in better agreement with the pressuremeter measurement.

Sarıçay Dam: a case study on in-depth seismic evaluation, deformation modulus and key geotechnical parameters

The Sarıçay Dam project in southwestern Türkiye integrates advanced geotechnical evaluation methods for building dams in areas with challenging geology and seismic activity. This study foregrounds an in-depth analysis of deformation modulus, the efficacy of consolidation grouting and shear strength parameters. It addresses critical issues such as encountering faults during construction and their mitigation, with the ‘observational approach’ being adopted to inform strategies and solutions and/or any modifications to these, including any design aspects. The appropriate selection of the deformation modulus and understanding its enhancement through consolidation grouting remain long-standing issues in geotechnical engineering. The comprehensive analyses of the deformation modulus revealed that certain empirical equations yield results comparable to those from in situ tests, although some may significantly overestimate; hence, correlating these tests with geophysical methods is crucial for accurate evaluation. Moreover, the deformation modulus results, derived from both rock pressuremeter and dilatometer tests on similarly characterized rock masses, displayed a notable comparability, despite the inherent scatter attributed to rock masses’ heterogeneity and anisotropy. The findings revealed that consolidation grouting, despite its minimal effect on increasing the deformation modulus (4–18%), plays a role in reinforcing the foundation by filling joints and fractures. The research experiences and outcomes on this project will contribute to the knowledge base for future dam projects.

Time-dependent deformation of marine gas hydrate-bearing strata conditioned to a wellbore: Experiments and implications

Natural gas hydrate (NGH) is a promising alternative energy resource, whereas marine NGH exploitation suffers from various potential geo-environmental concerns. The existence of a production wellbore not only provides channel for gas extraction, but also causes specific boundary conditions for the occurrence of geo-environmental risks. Almost all kinds of geo-environmental risks during NGH production initiate from time-dependent deformation of the near-wellbore strata. In this paper, the pressuremeter test (PMT) method was firstly introduced to investigate the lateral creep behaviors of the NGH-bearing sediment. The PMT probe was used to apply outwards lateral stress onto the hydrate-bearing sediment to simulate the horizontal stress state of the near-wellbore reservoir during drilling, completion, and/or hydraulic fracturing, during which the pressure inside the wellbore is higher than the reservoirs static pressure. The results indicated that the decelerated creep accounts for more than 70% of the lateral strain before the effective stress reaches the long-term strength. The hardening modulus of the sediment was proven to be increased from the magnitude of ∼102 MPa–∼103 MPa, when the hydrate saturation increases from 2.2% to 50.0%. The PMT creep test results can be used for interpretation of the in-situ horizontal stress and geomechanical parameters such as pro-plastic pressure and ultimate pressure. Based on the fact that PMT test results complies with the previous results from other techniques, a field-applicable PMT technique for NGH reservoir test is suggested to be developed in future study, and a systematic hypothesis and workflow for NGH reservoir modelling is also proposed in this study.

An extended graphical solution for undrained cylindrical cavity expansion in K0‐consolidated Mohr–Coulomb soil

AbstractThis paper develops a general and complete solution for the undrained cylindrical cavity expansion problem in nonassociated Mohr‐Coulomb soil under nonhydrostatic initial stress field (i.e., arbitrary values of the earth pressure coefficient), by expanding a unique and efficient graphical solution procedure recently proposed by Chen and Wang in 2022 for the special in situ stress case with . It is interesting to find that the cavity expansion deviatoric stress path is always composed of a series of piecewise straight lines, for all different case scenarios of K0 being involved. When the cavity is sufficiently expanded, the stress path will eventually end, exclusively, in a major sextant with Lode angle θ in between and or on the specific line of . The salient advantage/feature of the present general graphical approach lies in that it can deduce the cavity expansion responses in full closed form, nevertheless being free of the limitation of the intermediacy assumption for the vertical stress and of the difficulty existing in the traditional zoning method that involves cumbersome, sequential determination of distinct Mohr–Coulomb plastic regions. Some typical results for the desired cavity expansion curves and the limit cavity pressure are presented, to investigate the impacts of soil plasticity parameters and the earth pressure coefficient on the cavity responses. The proposed graphical method/solution will be of great value for the interpretation of pressuremeter tests in cohesive‐frictional soils.

Undrained cavity expansion-contraction analysis in CASM and its application for pressuremeter tests

Many geotechnical scenarios involve cavity unloading from a loaded state, particularly in pressuremeter tests, and the unloading data of pressuremeter tests has exceptional attraction as it is less disturbed by the insertion process. However, the analyses for continuous cavity loading and unloading (i.e., cavity initially experiences expansion and then contracts) in critical state soils are rarely studied. To this end, a novel semi-analytical solution based on the unified state parameter model for clay and sand (CASM) is proposed for the whole expansion-contraction of spherical and cylindrical cavities under undrained condition. The problem assumes that the cavity is unloaded after a monotonic loading stage, leading to plastic regions during both loading and unloading periods. The cavity response for the whole expansion-contraction process is investigated, with the total pressure and stress paths at the cavity wall presented and validated against numerical simulation. The developed solution is successfully implemented to interpret both loading and unloading data of pressuremeter tests. The undrained shear strength, in-situ effective horizontal stress and initial overconsolidation ratio are back analyzed by using a curve fitting method based on the proposed solution.

Method for Determining Foundation Bearing Capacity Based on Pressuremeter Test Curve

The pressuremeter test is a horizontal in-situ load test that can objectively reflect the lateral strength and deformation characteristics of the tested soil. The existing methods for determining the characteristic values of foundation bearing capacity through pressuremeter tests are mainly based on the pressure values corresponding to the starting and ending points of the straight line part of the lateral pressure load deformation curve, which has significant uncertainty. Based on the characteristics of the p-s curve, this article uses a cubic polynomial to fit the p-s curve, and the goodness of fit is greater than 0.99; gives a method for determining the characteristic values of foundation bearing capacity based on the pressure value at the inflection point of the p-s curve; and obtains the bearing capacity of the silty clay layer and the fine sand layer in the depth range of 46.0 meters. The calculation results show that compared with the near line method, the relative error of the bearing capacity characteristics of the foundation is within 20%, which can meet the engineering needs. This provides a new approach for determining the bearing capacity of foundations through lateral pressure tests.

Variability and loss of uniqueness of numerical solutions in FEM×DEM modeling with second gradient enhancement

AbstractIn the last decade, a new multi‐scale FEM×DEM approach has been developed using Finite Element Method (FEM) coupled with Discrete Element Method (DEM) as a constitutive law to account for the specificities of the mechanical behavior of granular materials. In FEM×DEM model, a DEM calculation is performed on a particle assembly (volume element—VE) at each Gauss point. Recent publications have demonstrated that FEM×DEM approach naturally captures the discrete and anisotropic nature of granular materials. Despite its advantages, FEM×DEM with classical FEM, suffers from mesh dependency, especially when material enters softening phase and exhibits strain localization. To overcome this limitation, FEM×DEM model has been enriched by incorporating a local second gradient model. Nevertheless, the existence of multiple possible solutions is observed. In this paper, we study the variability and loss of uniqueness of numerical solutions to a boundary value problem. Different VEs with equivalent mechanical properties are generated and used to model the pressuremeter tests by means of FEM×DEM. The modeling results show a great variability of the numerical results, both in shape of borehole and in different modes of shear bands. For the same VE, the loss of uniqueness of numerical solutions is evidenced by a slight modification of loading history at the level of the internal pressure applied to the borehole. Finally, we show that when a certain heterogeneity is introduced by using different VEs within the same BVP, even if the uniqueness of the solution is not guaranteed, the set of possible solutions seems more restrained.

Evaluation of using hardening soil model for predicting wall deflections caused by deep excavation: A case study at the Ho Chi Minh metro line 1, Vietnam

The goal of this study is to assess the application of the Hardening soil model in predicting the deformation of retaining walls of excavations in 2D and 3D finite element analysis at the Ho Chi Minh Metro project. Designed as the deepest underground station in the first metro line built in Ho Chi Minh City (HCMC), Opera House station is located in an area with a dense building zone and close to historical buildings. A summary of the input soil properties is provided using data from site investigations, in-situ tests, and laboratory tests. By numerical simulation using the Hardening soil model, the parameters of the soil stiffness modulus value are verified based on the Standard Penetration Test (SPT), and Pressuremeter test (PMT). The obtained results of the numerical analysis by 2D and 3D finite element methods, and field observations indicate that applying the Hardening soil model with soil stiffness modulus obtained in situ tests gives reasonable results on the displacement of the retaining wall at the final phase. The relationship between the SPT value and the stiffness modulus of HCMC sand is a function of depth. This correlation is obtained through the comparison of wall deformation between the simulation and monitoring at the construction site. The results of the difference between 2D and 3D finite element analysis also are discussed in this study.

Field testing of shear strength of granite residual soils

The characteristics of residual soils are very different from those of sedimentary soils. Although the strength characteristics of sedimentary soils have been studied extensively, the shear strength characteristics of granitic residual soils (GRS) subjected to the weathering of parent rocks have rarely been investigated. In this study, the shear strength characteristics of GRS in the Taishan area of southeast China (TSGRS) were studied by field and laboratory tests. The field tests consisted of a cone penetration test (CPT), borehole shear test (BST), self-boring pressuremeter test (SBPT), and seismic dilatometer Marchetti test (SDMT). The shortcomings of laboratory testing are obvious, with potential disturbances arising through the sampling, transportation, and preparation of soil samples. Due to the special structure of GRS samples and the ease of disturbance, the results obtained from laboratory tests were generally lower than those obtained from situ tests. The CPT and scanning electron microscopy (SEM) results indicated significant weathering and crustal hardening in the shallow TSGRS. This resulted in significant differences in the strength and strength parameters of shallow soil obtained by the BST. Based on the SDMT and SBPT results, a comprehensive evaluation method of shear strength for TSGRS was proposed. The SBPT was suitable for evaluating the strength of shallow GRS. The material index (ID) and horizontal stress index (KD) values obtained by the SDMT satisfied the empirical relationship proposed by Marchetti based on the ID index, and were therefore considered suitable for the evaluation of the shear strength of deep GRS.

Karakterisasi Tanah Vulkanik di Kabupaten Kediri, Jawa Timur, Indonesia Berdasarkan Uji CPT, SPT, dan PMT

Indonesia is a country surrounded by the Pacific Ring of Fire so that various areas are dominated by volcanic soil. Volcanic soils have unique and unusual characteristics, different structures and properties from soil in general, and are strongly influenced by geological processes. Volcanic soils were also found to be problematic and caused a lot of geotechnical damage. Research on volcanic soils from a geotechnical perspective in Indonesia is still very limited. This study aims to characterize volcanic materials in Kediri Regency, East Java, Indonesia, based on in situ testing using CPT (Cone Penetration Test), Standard Penetration Test (SPT), and Pressuremeter Test (PMT). CPT and SPT are the most common and frequently used field tests, while PMT is used to obtain horizontal stresses. Some data from the X-Ray Diffraction Analysis (XRD) test and corebox drilling results will also be used in this study. Field test results will display soil classification and parameters, which will then be combined, and empirical correlations will be obtained for site characterization as well as comparisons with other volcanic soil literature studies. The results showed that the volcanic soil in Kediri Regency consists of non-lateritic to lateritic soil. Based on the CPT and SPT correlations, it was found that the qc/N value was greater than in general soils for both cohesive and non-cohesive soils. The authors also found a relationship between parameters and interpretation of PMT data against NSPT for cohesive volcanic soils in the study area.

Evaluation of Jacking Forces in Weathered Phyllite Based on In Situ Pressuremeter Testing and Deep Learning

Pipe jacking is a trenchless technology used to install buried pipelines, such as sewer lines in wastewater management systems. Existing mechanistic approaches based on geomaterial strength parameters (i.e., friction angle and apparent cohesion) can provide an estimation of the potential jacking forces during construction. However, extracting intact rock cores for strength characterisation is challenging when dealing with highly weathered ‘soft rocks’ which exhibit RQD values of zero. Such was the case for a pipe jacking drive traversing the highly weathered lithology underlying Kuching City, Malaysia. Furthermore, mechanistic approaches face limitations during construction when jacking forces are dependent on operation parameters, such as jacking speed and lubrication. To address these knowledge gaps, the primary objectives of this study are the development of rock strength parameters based on in situ pressuremeter testing for the purpose of estimating jacking forces. Furthermore, this study investigates the influence of various pipe jacking operation parameters, with a particular focus on their impact on jacking forces in weathered ‘soft rocks’. To achieve this, a novel deep learning model with an attention mechanism is introduced. The proposed methods of rock strength parameters derived from pressuremeter testing and the utilisation of deep learning will help to provide insights into the key factors affecting the development of jacking forces. This paper successfully shows the use of in situ pressuremeter testing in developing Mohr–Coulomb (MC) parameters directly from the site. In addition, the developed deep learning model with an attention mechanism successfully highlights the significance of pipe jacking operation parameters with an accuracy of 88% in predicting the jacking forces.

Discussion of “Measuring strength and consolidation properties in lacustrine clay using piezocone and self-boring pressuremeter tests”

Discussion of “Measuring strength and consolidation properties in lacustrine clay using piezocone and self-boring pressuremeter tests”

Correlation of Pressuremeter Test Results with SPT N Values and Liquidity Index for Cohesive Soil of Normal Calcutta Deposit

Correlation of Pressuremeter Test Results with SPT N Values and Liquidity Index for Cohesive Soil of Normal Calcutta Deposit

The monotonic behaviour of a low- to medium-density chalk through in-situ and laboratory characterisation

Chalk is a highly variable cemented biomicrite limestone that can show widely different rock strengths and patterns of micro to macro fissuring and jointing, due to variations in depositional environments and local geological histories. This paper describes the characterisation of a very weak to weak, low- to medium-density chalk through in situ profiling and laboratory testing, which provided new insights into the geomaterial’s mechanical behaviour. The chalk de-structures when taken to large strains, leading to remarkably high pore pressures beneath penetrating cones and degraded responses in full-displacement pressuremeter tests. Laboratory tests on carefully formed specimens explored the chalk’s unstable structure and marked time-, rate- and pressure dependency. A clear hierarchy was found between profiles of peak strength with depth from Brazilian tension, drained and undrained triaxial and direct simple shear tests conducted from in-situ stress conditions. Highly instrumented triaxial tests sheared from low confining stresses indicated stiffness anisotropy and showed very brittle failure behaviour from small strains. Progressively more ductile behaviour was seen as confining pressures were raised, with failures being delayed until increasingly large strains and finally stable critical states were attained. The chalk’s mainly sub-vertical jointing and micro-fissuring led to properties depending on specimen scale, with high-quality laboratory stiffness measurements significantly exceeding those obtained from in-situ geophysical testing, which far exceed the operational stiffnesses of the chalk mass. While compressive strength and stiffness appear relatively insensitive to effective stress levels, consolidation to higher pressures closes micro-fissures and reduces anisotropy. The results provided the basis for numerical analysis with advanced constitutive models that inform the interpretation of axial and lateral tests on driven piles and inform the development of new practical design methods.