High-strength mortar (HSM) gradually has wide applications due to its exceptional strength, micro-expansion properties, and excellent fluidity. Behavior deterioration of structures in saline soil areas is primarily attributed to freeze-thaw cycles and sulfate attack. In this study, the coupling effect of freeze-thaw cycles and sulfate attack on the appearance, mass loss, and relative dynamic elastic modulus of HSM was investigated during erosion. Then, compressive experiments were conducted to assess the mechanical properties of HSM subjected to both freeze-thaw cycles and sulfate attack. The influences of coupling freeze-thaw cycles and sulfate attack on the compressive properties of HSM were quantified through regression analysis of experimental results. Empirical models for compressive stress-strain curves and damage constitutive behavior of HSM were developed, taking the coupled adverse effect into account. The results indicate that the coupled effect of freeze-thaw cycles and sulfate attack causes performance deterioration of HSM. The empirical models reproduce the compressive behaviors of HSM subjected to freeze-thaw cycles and sulfate attack.

The under-consolidated state affects the deformation behavior of deep excavation in soft soil and poses potential risk to the safety of adjacent facilities. However, the deformation model of deep excavation in under-consolidated ground has not been well investigated yet. This study presents a series of numerical analyses on the deformation characteristics of deep excavations in under-consolidated and normally-consolidated ground, each of which is retained by diaphragm walls with rigid struts and a bottom improvement layer. Under-consolidated cases without excavation activities (i.e., simplified as Consolidate cases) were also included for comparison. The modelling results showed that, with the lateral constraint of inner rigid support system, the under-consolidated ground resulted in only a slight increase of lateral wall deformation but a significant increase in ground settlement as compared to normally-consolidated ground. The under-consolidated ground with lower initial average consolidation ratio, thicker surface fill, higher permeability, and longer construction period produced greater wall deformation and ground settlement during excavation. Besides, this study proposed an empirical method to estimate the settlement envelope for deep excavation in under-consolidated ground as the superposition of two parts: settlement induced by excavation activities, and settlement induced by residual consolidation with consideration of average consolidation ratios before and after excavation.

Understanding the temperature-dependent behavior of sands is essential for geotechnical engineering applications, especially in environments with long-term temperature variations. This study investigates the effects of temperature (T) on the shear strength and creep deformation (Delta epsilon CP) of KMUTT and Hostun sands through a series of consolidated drained triaxial compression (CDTC) tests. Monotonic loading (ML) and sustained loading (SL) schemes were applied to evaluate shear strength and creep behavior under various stress levels (SL) and temperatures. The temperature effect parameter (Af) was introduced to quantify the reduction in shear strength at elevated T relative to a reference temperature (T0 = 30 degrees C). Experimental results show that shear strength decreases as temperature increases, with Hostun sand being more temperature-sensitive than KMUTT sand. Under SL, significant Delta epsilon CP was observed, increasing with both SL and T, while resumption of shearing after SL did not affect peak shear strength. A hyperbolic empirical equation was developed to predict Delta epsilon CP for a given creep duration (Delta tCP), SL, and T, incorporating temperature effects via Af. The model was validated with experimental results and showed strong predictive capability, especially during the primary creep stage. However, discrepancies appeared at high SL, where secondary creep effects became more pronounced. The proposed model offers a practical framework for predicting long-term creep deformation in sands under temperature variations, enhancing geotechnical design in thermally influenced environments.

Offshore wind turbines (OWTs) are subjected to prolonged external loading, including loads induced by wave action. The soil undergoes bi-directional coupled shear, due to this low-frequency and long-duration loading, the cumulative deformation of the offshore foundation is observed to increase, which poses a threat to the functional reliability of the offshore wind turbines. The soil around the piles is distributed with clay layers. Due to the complex mechanical properties of clay, bi-directional cyclic loading tests are performed to research the drainageinduced deformation characteristics of clays in this paper. Based on these test results, the variation of hysteresis loops of stress-strain, resilient modulus, and the cumulative strain are found to exhibit a strong correlation with both the cyclic stress level and the confining pressure. The stress-strain hysteresis loops and resilient modulus have significantly different trends at higher or lower cyclic stress levels. Then an empirical model that uniformly reflects the strain-hardening and softening characteristics, and an empirical model reflects the characteristics of cumulative strain development in soils is established. Finally, the performance of the permanent cumulative strain prediction model is assessed based on the in-situ test findings from the clay foundation.

Despite significant advances in laboratory testing in recent decades, geotechnical designs that incorporate data from in-situ testing remain predominant worldwide. One of the most commonly employed techniques for correlating soil mechanical properties is the standard penetration test. However, while this test provides valuable information for identifying soil strata and offering general descriptions of soil characteristics, its correlation with shear strength parameters has several limitations that are often overlooked. In this article, we aim to i) present a critical literature review concerning the applicability of correlations between the undrained shear strength of fine-grained soils and standard penetration test data; ii) estimate the uncertainties associated with the adoption of these empirical correlations, which are frequently disregarded in engineering practice; iii) present simulation results from typical slope stability analyses, taking into account the uncertainties associated with the estimation of the undrained shear strength. The findings of our study suggest that geotechnical engineers should exercise caution when using such simplified equations, as they often lead to underestimations or overestimations of the stability of geotechnical structures.

The seismic effects of complex, deep, and inhomogeneous sites constitute a significant research topic. Utilizing geological borehole data from the Suzhou urban area, a refined 2D finite element model with nonuniform meshes of a stratigraphic crossing the Suzhou region was established. Within the ABAQUS/explicit framework, the spatial inhomogeneity of soils, including the spatial variation of S-wave velocity structures, was considered in detail. The nonlinear and hysteretic stress-strain relationship of soil was characterized using a non-Masing constitutive model. Ricker wavelets with varying peak times, peak frequencies (fp), and amplitudes were selected as input bedrock motions. The analysis revealed the spatial distribution characteristics of 2D nonlinear seismic effects on the surface of deep and complex sedimentary layers. The surface peak ground acceleration (PGA) amplification coefficients initially increased and then decreased as fp increases. The surface PGA amplification was most pronounced when the fp is close to the site fundamental frequency. Additionally, when fp = 0.1 Hz, the surface PGA amplification was found to depend solely on the level of bedrock seismic shaking, with amplification factors ranging from 1.20 to 1.40. Furthermore, the ensemble empirical mode decomposition components of seismic site responses can intuitively reveal the variations in time-frequency and time-energy characteristics of Ricker wavelets as they propagate upward from bedrock to surface.

The pressuremeter test is a widely used in-situ test method in geotechnical engineering for determining ground properties. It is applicable to all types of soil and weak rocks, it records soil deformation under loading conditions. This paper presents a literature review on the application of the pressuremeter test in evaluating the behavior of foundations under load. It explores the methods used to interpret pressuremeter test data in various soil types, reviews the different analytical models employed, and focuses on approaches for assessing the behavior of foundations using pressuremeter test results. The achievements and limitations of each method are presented and discussed. Despite the extensive literature on the applications, interpretation, and development of the pressuremeter test, its use in evaluating the behavior of foundations under load remains limited. This work seeks to address this research gap by identifying challenges in utilizing pressuremeter test data for such analyses and providing recommendations for future research. This work aims to encourage further investigation into the potential of pressuremeter tests for advancing the understanding of foundation behavior under loading conditions.

The offshore wind turbines (OWT) are subjected to cyclic loads, such as ocean waves and wind, over extended periods. The soil surrounding the pile experiences bi-directional cyclic shear. As a result of the low-frequency and long-term loading in the pile-soil interaction, the cumulative deformation of pile foundation increases, posing a risk to the operational safety of wind turbine system. The soil around the piles is distributed with soft clay and clay layers. To study the cumulative deformation properties of clay under complex stress states. A series of tests are conducted, the variation of resilient modulus under different cyclic stress levels and confining pressures is analyzed based on test results. Then an empirical model uniformly reflecting strain-hardening and strainsoftening properties of clay is proposed. The variations of model parameters are investigated. Then the established empirical model is used to modify the maximum elastoplastic modulus at each unloading within the bounding surface constitutive model, a parameter reflecting the magnitude and rate of strain accumulation is also introduced. This method is characterized by a simple expression and requires fewer model parameters. Finally, the predicted results of modified constitutive model are compared with test results to verify the validity of the established model.

This study explores the mechanical properties of casein-treated and agar-treated sand, considering biopolymer content, dehydration time, immersion periods, relative densities, porosity ratios, and porosity/volumetric biopolymer contents. Adding casein was found to improve the water resistance of agar-treated sand. Results reveal that 4 % and 5 % casein-treated sand exhibit the highest water resistance after a week of submersion, with wet strength of 0.359 MPa and 0.493 MPa, respectively. Increased relative density and biopolymer content correlate with higher unconfined compressive strength, inversely linked to sample porosity. An empirical equation connecting unconfined compressive strength to porosity/volumetric biopolymer content is derived.

Seismic Site Characterization involves the qualitative assessment of top-soil properties that have the capability of amplifying the generated earthquake ground motions. The geotechnical properties of topsoil refer to the top 30m subsurface profile which plays a vital role in seismic microzonation and Ground Response Analysis (GRA) studies. Among various geotechnical parameters, shear-wave velocity (Vs) of the top 30 m subsurface is mainly linked to seismic site characterization and amplification studies. The average shear-wave velocity of the top 30 m subsurface, Vs(30), has been used for seismic site classification in accordance with the National Earthquake Hazard Reduction Program (NEHRP) and various building codes. In this study, an attempt has been made to retrieve the geospatial variation of average shear-wave velocity for Coimbatore city using the active Multichannel Analysis of Surface Waves (MASW) test which is one of the non-destructive geophysical tests. To retrieve the spatial distribution of shear-wave velocity (Vs), the test was carried out at 35 locations in the vicinity of important structures, schools, colleges, and hospitals within the city. The seismic records have been acquired in the field and analyzed using the winMASW software. From the one-dimensional MASW test, the study area has an average Vs(30) in the range of 640 m/s to 909 m/s and has been classified as site-class BC (soft rock) according to NEHRP standards. These test results have been validated using the collected SPT bore log data from various locations, including 40 sites in the vicinity of the conducted MASW tests. The site-specific correlation between the shear-wave velocity (Vs) and the corrected SPT N- Value, N1(60), and between Vs and shear modulus (G) have been developed for Coimbatore city with a regression coefficient of 0.79 and 0.83 respectively. From the fundamental site period map, the study area has a site period in the range of 0.1 to 0.2 s, which indicates that 1to 2- storey buildings that are densely distributed throughout the city may lead to damage in case of probable future earthquakes. This study bridges the connectivity from the evaluated bedrock acceleration using the Seismic Hazard Analysis (SHA) and provides insights for evaluating surface acceleration using GRA studies.