Hasil untuk "Engineering geology. Rock mechanics. Soil mechanics. Underground construction"

XU Peng 1, MENG Yuhan 2, LI Ting 2, YANG Guangqing 2

The Material Point Method (MPM) is a mesh-free simulation technique that integrates the advantages of Lagrangian and Eulerian methods, providing a novel approach for simulating large deformations of slopes subjected to rainfalls. A two-dimensional two-phase single-point MPM is employed to analyze slope responses under short-duration heavy rainfall with varying soil saturated permeability coefficients and rainfall intensities. The research findings indicate that: (1) The onset of slope instability is delayed as the intensity of short-duration heavy rainfall decreases. Concurrently, the displacement curve at the slope toe transitions from rapid steep increases to gradual increments during instability progression. (2) Primary failure modes under short-duration heavy rainfall manifest as deep and shallow overall sliding or retrogressive sliding, with the latter exhibiting greater destructive potential. Under identical rainfall intensities, slopes with lower and higher saturated permeability coefficients tend to result in shallow and deep sliding failures, respectively. (3) Decreasing soil saturated permeability coefficients progressively weakens the influence of rainfall intensity on both the magnitude and distribution patterns of pore water pressure within slopes.

Tian Lan, Ran Hu, Xi-Ning Su et al.

The capillary pressure curve provides fundamental insights into the dynamics of fluid-fluid displacement and phase distributions. Capillary scaling is crucial for extrapolating capillary pressure-saturation data from laboratory tests to field applications. However, the classic scaling method fails to capture the effect of wettability as the pore surface approaches neutral wetting. Here, inspired by the role of pore-filling events in controlling fluid-fluid displacement, we perform a theoretical analysis of the burst events occurring during drainage processes. We find that the median threshold capillary pressure, which corresponds to the occurrence of burst events for the median pore throat, is closely correlated with the capillary pressure curve across various contact angles. Using this concept, we propose a new scaling method for capillary pressure curves under various wetting conditions. We conduct microfluidic experiments and pore-network modeling across different contact angles, porosities, and disorders to evaluate the new scaling methods, indicating that the new scaling method performs better than the Leverett J-function as the contact angle approaches 90°. We further perform geometry analysis on the critical radius of curvature for burst events in an ideal tetrahedral arrangement and extend the new scaling method to 3D (three-dimensional) porous media. Model evaluation shows that the 3D version of the scaling method also performs well but requires fewer parameters compared to the Leverett J-function. Our work enhances the prediction and interpretation of experimental data for capillary pressure curves under various wet conditions, and more importantly, establishes a methodology that relates Darcy-scale flow behavior to pore-scale fluid displacements.

Wei Zhang, Huijian Fu, Yingke Liu et al.

Abstract In coal mines, dynamic disasters such as rock bursts seriously threaten the safety of mining activities. Exploring the dynamic behaviors and disaster characteristics in the impact failure process of coal serves as the basis and prerequisite for monitoring and warning rock bursts. In this context, impact failure tests of coal were carried out under different axial static loads and impact velocities to analyze the dynamic behaviors and acoustic emission (AE) response characteristics of coal. The results show that the dynamic behaviors of coal under combined dynamic and static loads are significantly different from those under static loads, and the stress‐strain curve displays double peaks without an obvious compaction stage. As the axial static load grows, the dynamic strength and peak strain both have a quadratic function with the axial static load. When the coal damage intensifies instantaneously, the AE count and energy parameters both witness pulse‐like increases and reach their peak values. The damage effect of axial static loads on coal, though limited, has an extreme point. In contrast, the impact velocity can strengthen the response of AE signals and has linear function relationships with the peak values of AE count and energy. This plays a leading role in the damage to samples and sets a critical point for coal failure and fracture. Compared with the analysis results of stress and strain, the responses of AE signals are more accurate and reliable. Based on AE response characteristics, the damage evolution process of coal under the combined dynamic and static loads can be identified more accurately to reveal the moment corresponding to coal damage and the characteristics of coal failure. The research results are conducive to the further application of AE monitoring methods to early warning of rock burst disasters in coal mining sites.

Mahdieh Azimi, Amin Soltani, Mehdi Mirzababaei et al.

WANG Jun 1, 2, 3, 4 , ZHANG Kaiyu 1, NI Junfeng 1, 2, 3, 4 , FU Hongtao 1, 2, 3, 4, PENG Yi1

To address the issues of poor permeability and long consolidation time of dredged sludge, the flocculation-vacuum preloading method has been widely employed to treat such soil. For the existing soft soil foundation, a combined method that integrated grouting flocculation and vacuum preloading was proposed. The indoor model tests were conducted on the dredged sludge with varying initial water contents where different lime contents were controlled. The changes of the pore water pressure, displacement and settlement were monitored. The pH, salinity, water content and vane shear strength of soil were measured after the tests. The optimal lime content, considering the influence of strength growth and soil salinization, was determined for the grouting flocculation-vacuum preloading. Then the efficacy of the combined method was further verified through its application in Longwan Phase Ⅱ coastal wetland restoration project. The results of this study can be used as a design reference for the applications of the combined method in other similar projects.

LIAO Raoping 1, CHEN Yonggui 1, 2 , LIU Cong 1, YE Weimin 1, 2, WU Dongbei 3, WANG Qiong 1, 2

The highly compacted bentonite, as the preferred buffer/backfill materials, is inevitably subjected to chemical erosion in the T-H-M-C environment of the high-level radioactive waste repositories, leading to dissolution or phase transition of smectite, and diminishing the buffer performance. The latest researches on the chemical mechanism are summarized on the basis of reviewing the effects of the solution on the buffer performance of the compacted bentonite. The analysis indicates that the dissolution or phase transformation of layered smectite into a framework mineral is the key factor leading to the attenuation of the specific surface area, density, water retention, swelling and permeation resistance of bentonite. The chemical interaction mechanisms include mineral phase transformation and chemical cementation. The phase transformation of minerals is influenced by chemical composition, pH, temperature and catalytic ions of the pore solution, and can be divided into isomorphous phase transformation and recrystallization. The chemical cementation associates with saline precipitate filling and the cementation of aluminosilicate gelation during wetting-drying cycles. The dissolution rate of minerals in bentonite is influenced by both the intrinsic factors like surface area and stress, and the extrinsic factors including pore solution. Further clarification of chemical reaction parameters, cementation effects and multi-field coupling reaction model within the bentonite reaction system remains the focus of further researches on the chemical evolution of bentonite in the future.

Liangjie Gu, Xia-Ting Feng, Rui Kong et al.

Surrounding rocks at different locations are generally subjected to different stress paths during the process of deep hard rock excavation. In this study, to reveal the mechanical parameters of deep surrounding rock under different stress paths, a new cyclic loading and unloading test method for controlled true triaxial loading and unloading and principal stress direction interchange was proposed, and the evolution of mechanical parameters of Shuangjiangkou granite under different stress paths was studied, including the deformation modulus, elastic deformation increment ratios, fracture degree, cohesion and internal friction angle. Additionally, stress path coefficient was defined to characterize different stress paths, and the functional relationships among the stress path coefficient, rock fracture degree difference coefficient, cohesion and internal friction angle were obtained. The results show that during the true triaxial cyclic loading and unloading process, the deformation modulus and cohesion gradually decrease, while the internal friction angle gradually increases with increasing equivalent crack strain. The stress path coefficient is exponentially related to the rock fracture degree difference coefficient. As the stress path coefficient increases, the degrees of cohesion weakening and internal friction angle strengthening decrease linearly. During cyclic loading and unloading under true triaxial principal stress direction interchange, the direction of crack development changes, and the deformation modulus increases, while the cohesion and internal friction angle decrease slightly, indicating that the principal stress direction interchange has a strengthening effect on the surrounding rocks. Finally, the influences of the principal stress interchange direction on the stabilities of deep engineering excavation projects are discussed.

Mojtaba Mohammadi, Hossein Jahantigh, Farahad Zolfaghari

Introduction Evaporation, the process by which water molecules escape a surface after absorbing sufficient energy to overcome vapor pressure, is a major contributor to water scarcity, especially in arid and semi-arid regions where heat readily facilitates this escape. Accurately estimating evaporation losses is crucial for effective water resource management, crop water demand prediction, and irrigation scheduling. Machine learning (ML) has emerged as a powerful tool for tackling the complex and stochastic nature of environmental problems. ML models excel at identifying relationships between predictor variables and outcomes (predictands), often surpassing traditional methods. However, their performance can vary depending on input factors and climatic conditions. Recently, hybrid techniques that combine multiple models have gained traction in climate and hydrology studies. These techniques leverage the strengths of different approaches within a single algorithm, potentially capturing more complex patterns in data series. This research will explore the potential of various individual ML models and propose a novel hybrid approach for estimating pan evaporation in Sistan and Baluchistan Province.   Materials and Methods This study investigates pan evaporation simulation and prediction in Sistan and Baluchistan Province, Iran. Synoptic station data (1980-2019) served as model inputs, while pan evaporation measurements from these stations provided the observed values. In this research, in the approach of individual performance of data mining models, eight data mining models were used to simulate and predict evaporation from the pan. In addition to the individual performance approach, the combined VEDL approach was used to provide a hybrid model (a combination of the mentioned eight individual models of deep learning). In this hybrid approach to regression issues, the estimators of all models are averaged to obtain an estimate for a set called vote regressors (VRs). There are two approaches to awarding votes: average voting (AV) and weighted voting (WV). In the case of AV, the weights are equivalent and equal1. A disadvantage of AV is that all of the models in the ensemble are accepted as equally effective; however, this situation is very unlikely, especially if different machine learning algorithms are used. WV specifies a weight coefficient for each ensemble member. The weight can be a floating-point number between Zero and one, in which case the sum is equal to one, or an integer starting at one denoting the number of votes given to the corresponding ensemble member. the weight of each model was selected based on the accuracy of the model's performance using the evaluation criteria obtained from the training implementation section of individual models. the model’s performance was assessed using statistical measures, including R2, RMSE, MAE, and Taylor diagram.   Results and Discussion The results showed that all the models had very good results in both the training and testing stages. All models exhibited excellent performance during training and testing. The Artificial Neural Network (ANN) achieved the highest accuracy in both phases at the Zahedan station (R² = 0.89, RMSE = 45.95 in training; R² = 0.96, RMSE = 44.18 in validation). It emerged as the best model for monthly pan evaporation prediction at this station. Other models also performed well, with the Support Vector Machine (SVM) and Random Forest (RF) models achieving R² values of 0.89 and 0.88 in training, respectively. Notably, the BART model ranked second in validation (R² = 0.96). The Tree Model (TM) had the lowest accuracy (R² = 0.84 and 0.93 in training and validation, respectively). Across all stations, ANN, SVM, and RF consistently delivered the best results in both training and testing. In the test phase, the SVM model outperformed others in Khash, Iranshahr, and Chabahar stations (R² = 0.94, 0.96, and 0.94, respectively). At the Saravan station, the RF model achieved the highest R² (0.94) during testing. To develop a hybrid data mining model, the Voting Ensemble for Deep Learning (VEDL) technique was employed with weighted voting in the training stage. The combined model significantly improved upon the best individual model. RMSE decreased from 45.95 to 33.1, R² increased from 0.89 to 0.94, and MAE improved from 32.92 to 23.9. Evaluation using the Taylor diagram further confirmed the superior performance of the VEDL model compared to the individual ANN model.   Conclusion The results showed that among all the models, ANN, SVM, and RF models had the best performance in the two stages of training and verification. In the validation stage, the SVM model with R2 values equal to 0.94, 0.96, and 0.94 performed best in the Khash, Iranshahr, and Chabahar stations. At the Saravan station, in the Sensji validity stage, the RF model with an R2 value of 0.94 had the best performance among the models. The excellent performance of the models in the two stages of training and validation is another finding of the research, These results are consistent with the results of researchers who have expressed the appropriate efficiency of machine learning models in estimating evaporation/evaporation and transpiration in different climatic regions of Iran. The results of the combined model showed that the combined model improved the results compared to the best individual model so that the RMSE values increased from 45.95 to 33.1, the R2 values increased from 0.89 to 0.94, and the MAE value improved from 32.92 to 23.9. The use of the VEDL approach to estimate evaporation from the pan was a new approach that has not been used in past studies. Therefore, according to the results of this research, the proposed deep sensing model is proposed to estimate the evaporation of arid and semi-arid areas for water resources management and agricultural planning.

Lingxiang Wei, Dongjun Guo, Junyuan Ji et al.

Subways, underground logistics systems and underground parking, as the primary facilities types of underground, contribute significantly to the achievement of carbon–neutral cities by moving surface transportation to underground, thereby releasing surface space for the creation of more urban blue-green space for carbon sink. Therefore, in-depth studies on carbon neutrality strategies as well as reliable layout optimization solutions of these three types of underground facilities are required. This study proposes a spatial layout optimization strategy for carbon neutrality using underground hydrogen storage and geothermal energy for these three types of underground facilities employing a multi-agent system model. First, three spatial layout relationships, competition, coordination, and followership, between five underground facilities that contribute to emission reduction were investigated. Second, the implementation steps for optimizing the spatial layout of underground facilities were determined by defining the behavioral guidelines for spatial environment, underground facility, and synergistic agent. Finally, using the Tianfu New District in Chengdu City, China, as a case study, layouts of underground facilities under three different underground space development scenarios were simulated to verify the model. The findings of this study address the gap in the research on underground spatial facilities and their layout optimization in response to emission reduction. This study provided a significant reference for the study of underground space and underground resources at the planning level to aid in achieving carbon–neutral cities.

Wenhao SHAN, Lin WANG, Xiang'en WU et al.

Objective Accelerated the generation of natural gas hydrate is crucial for advancing hydrate-based technologies such as gas storage, gas separation, and CO2 capture. Methods The kinetic characteristics of methane hydrate generated with the wB=0.05% functionalized (hydroxylated, carboxylated, and aminated) multi-walled carbon nanotubes(MWCNT) system, and in combination with the wB=1.0% L-leucine were investigated through constant temperature and constant volume methods. Results The combination of multiwalled carbon nanotubes and carboxylated and hydroxylated multiwalled carbon nanotubes with L-leucine, significantly reduced the induction time for natural gas hydrate nucleation to approximately 25, 22, and 13 minutes, respectively. This promotion effect is comparable to that of the typical promoter sodium dodecyl sulfate, and the promotion effect is better than that of a single additive system. The methane storage density of the compounded system reached 136-142 mg/g. Analysis of both the average and instantaneous methane uptake rates indicated that multiwalled carbon nanotubes had minimal impact on the growth kinetics of methane hydrate during the growth phase. The growth of methane hydrate in both the compounded and L-leucine systems were similar, characterized by a rapid increase in uptake rate to a peak value, followed by a rapid decrease and eventual completion of the growth phase. Conclusion A comprehensive analysis suggests that the combination of MWCNTs and L-leucine synergistically enhances the nucleation rate of methane hydrate, whereas the process and rate of the growth phase are predominantly influenced by L-leucine. This study presents a new idea for exploring the differentiation mechanism of different types of additives in enhancing the kinetics of methane hydrate generation.

Rafał Misa, Anton Sroka, Mateusz Dudek et al.

Monica Ghirotti, D. Donati, D. Stead

The Research Topic “Developments of Remote Sensing and Numerical Modeling Applications for Landslide Analysis” gathers high-quality original research articles on case studies covering a broad spectrum of subaerial landslide types from a wide range of places throughout the world. The common factor of these contributions is the application of state-ofthe-art and new remote sensing techniques, numerical modeling methods, and their combination, for the characterization, monitoring and simulation of the behaviour and the geomorphic evolution of landslides. Where traditional survey methods are used, the Research Topic of geological data required to characterize landslides may be limited or prevented by difficult terrain and the state of activity of the slopes. The use of remote sensing techniques can help overcome these challenges, at the same time allowing monitoring of surface slope displacements and mapping of slope damage features. Multi-sensor, multi-platform, and multi-temporal datasets and approaches maximize the quality and the quantity of remotely sensed data to better characterize the behaviour and the spatial-temporal evolution of landslides. Identification and interpretation of the mechanism and factors controlling the behaviour and the evolution of the landslide can be tested using numerical modelling analyses. Simulations conducted using continuous, discontinuous, and hybrid numerical analyses can be validated and constrained against field andmonitoring data, therebymaking them an important tool to support and substantiate hypotheses and geological interpretations of the mechanisms and factors influencing the behavior of landslides in both natural and engineered slopes. Addressing these Research Topic requires a multidisciplinary approach encompassing engineering geology, rock and soil mechanics, structural geology, and geomorphology. This Research Topic adds to the state of knowledge of landslides (s.l.) through contributions dealing with case studies of landslide that employ or combine different remote sensing and/or numerical modelling methods to investigate the behavior and evolution of present and past landslides. Research Topic addressed in this Research Topic include the application of state-of-the-art remote sensing techniques for landslide mapping and characterization at various scales (Donati et al., Rouhi et al. Muhammad et al.), landslide susceptibility mapping (Titti et al.), landslide and landslide dam evolution analysis (Bonneau et al., Rabus et al., Wolter et al.), and numerical OPEN ACCESS

H. Jiang, T. Balz, J. Li

Abstract. Satellite Interferometric Synthetic Aperture Radar (InSAR) is widely utilized for topographic, geological, and natural resource investigations. However, many existing InSAR studies on ground deformation are limited to relatively short observation periods and single sensors. This paper introduces a novel method for fusing multi-sensor InSAR time series data, specifically designed to address scenarios involving partial overlaps and temporal gaps. The method employs a new Power Exponential Knothe Model (PEKM) to fit and fuse overlaps in the deformation curves, while a Long Short-Term Memory (LSTM) neural network predicts and fuses data during temporal gaps in the series. In this study, the city of Wuhan in China was selected as the experimental area. SAR datasets from COSMO-SkyMed (2011–2015), TerraSAR-X (2015–2019), and Sentinel-1 (2019–2021) were fused to map long-term surface deformation over the past decade. An independent InSAR time series analysis from 2011 to 2020, based on 230 COSMO-SkyMed scenes, was used as a reference for comparison. The correlation coefficient between the fusion algorithm’s results and the reference data is 0.87 in the time overlapping region and 0.97 in the time-interval dataset. The overall correlation coefficient of 0.78 demonstrates that the proposed algorithm achieves a similar trend as the reference deformation curve. Based on the long time series settlement results obtained through fusion, a detailed analysis of the causes of settlement was conducted for several subsidence zones. The subsidence in the Houhu area is primarily attributed to the consolidation and compression of soft soil. Soil mechanics were employed to estimate the expected completion time of subsidence and calculate the degree of consolidation for each year. The COSMO-SkyMed PSInSAR results indicate that the area has entered the late stage of consolidation and compression, gradually stabilizing over time. Furthermore, the subsidence curve observed in the area around Xinrong reveals that the construction of an underground section of subway Line 21 has caused significant settlement in that particular region. The high temporal granularity of the PSInSAR time series also enables precise detection of a rebound phase following a major flooding event in 2016. The experimental results demonstrate the accuracy of the proposed fusion method in providing robust time series for analyzing long-term land subsidence mechanisms. Additionally, these findings unveil previously unknown characteristics of land subsidence in Wuhan, thus clarifying the relationship with urban causative factors.

Akiyoshi Kamura, Tomomi Kaneko, Noboru Sato et al.

Check dams constructed in steep mountainous areas require the rationalization of the dam body and foundation system. In general, soil cement replacement or caissons are often adopted for foundations. In such cases, reducing the construction effort is a critical issue. To address this, the authors studied the viability of a new type of check dam foundation consisting of a group of micropiles whose heads are structurally disconnected from the dam body. The system, coined a head-separated micropile group (HMG) foundation, enables the saving of labor and a reduction in the cross-sectional forces applied to the micropiles. Firstly, a full-scale loading test of the HMG was conducted. Then, a finite element model was formulated and its parameters fitted to make it suitable for reproducing the experimental results. Finally, using the FE model, the performance of a typical rigidly connected micropile foundation and that of the HMG system were compared in terms of the bearing capacity and displacement of the check dam body. The results confirmed that, although its displacement was 1.25 times larger than that of the rigidly connected foundation, the HMG system led to a factor of safety of 3.5 against micropile buckling.

Jian Wu, Quansheng Liu, Xiaoping Zhang et al.

The radiated seismic energy is an important index for the intensity assessment of microseismic (MS) events and the early warning of dynamic disasters. However, the energy of MS signals is significantly attenuated due to the heterogeneity and viscous damping of rock media. Therefore, the study on attenuation characteristics of MS signals in underground engineering has practical significance for the accurately estimation of radiated seismic energy. Based on a pendulum impact test facility and MS monitoring system, an in situ investigation was carried out to explore attenuation characteristics at a deep tunnel. The results show that the seismic energy and peak particle velocity (PPV) attenuation are exponentially related to the propagation distance. The attenuation coefficient of energy is larger than that of PPV. With the increase in the input impact-energy, the seismic energy attenuation coefficient decreases as a power function. An empirical relationship between energy attenuation coefficient and wave impedance of rock mass was established in this scenario. Moreover, the time-frequency characteristics and energy distribution laws of impact-induced signals were investigated by the continuous wavelet transform (CWT) and wavelet packet analyses, respectively. The dominant frequency of signals decreases gradually as the propagation distance increases. Based on the energy attenuation characteristics, a new method was proposed to calculate the released source energy of MS events in the field. This study can provide an insight into energy attenuation characteristics of seismic waves and references for attenuation correction in seismic energy calculation.

Zhixiang Chen, Xiaoxia Guo, Longtan Shao et al.

In the construction of artificial freezing methods and cold region engineering, the determination of the accurate temperature field is the demand of both ensuring the stability of frozen soil and reducing the project investment. Affected by the external environment, phase change latent heat, non-linear thermal parameters, etc., the temperature evolution of the soil freezing process is a non-linear form, and the temperature field evolution will be more complex with the change of different influencing factors. Scientific control and utilization of the influencing factors of the frozen soil temperature field play a vital role in improving the freezing efficiency and accuracy of the soil temperature field. This study aims to analyze the sensitivity of thermal factors on the nonlinear formation process of frozen soil temperature field, and to provide the results for the control of various factors in frozen soil engineering. A freezing model test was designed and implemented, the boundary conditions and temperature evolution in the model were monitored. Meanwhile, the thermal parameters and unfrozen water content of the model soil were tested indoor. Then the theoretical relationship between unfrozen water content and parameters was deduced to determine the variation range of unfrozen water content. The boundary condition values (including the maximum, minimum and average values) and thermal parameters were used in the orthogonal simulation of the freezing model, respectively. The temperature simulation values were compared with the model test values, and the factors affecting the nonlinear heat transfer of frozen soils were analyzed quantitatively by both the range method and variance analysis method. Several suggestions of the vital factors in the soil freezing construction were offered based on this research.

ZHANG Chuang, REN Song, ZHANG Ping et al.

Phylite is widely distributed in southwest of China. Factors such as groundwater, bedding, micro-pores and micro-cracks will weaken its mechanical properties to some extent, thus posing severe challenges to the stability of the related projects. Therefore, in this paper, based on Brazilian splitting test, the evolutions of the tensile strength, energy and failure forms of phyllite under the coupling effects of water, bedding and pore are studied. The results show that the tensile strength decreases gradually with the increase of moisture content, pore diameter and bedding angle. However, the tensile strength has different sensitivities to the changes of them, which is mainly reflected in that bedding angle is the most significant, pore diameter is the second, and moisture content is the least. The tensile strength shows obvious anisotropy under different beddings. The anisotropy of tensile strength increases with the increase of water content and pore diameter, and the rate of increase with water content is more significant. Moreover, the energy increases gradually with the increase of moisture content, pore diameter and bedding angle, which is consistent with the changes of tensile strength. Although the energy under different beddings also presents obvious anisotropy, its anisotropy degree is generally higher than that of the tensile strength under the same condition. The failure form of specimens is affected by pore size, bedding angle and moisture content, among which, the existence of hole mainly affects the crack initiation position, the size of pore mainly affects the crack initiation strength, the bedding angle mainly affects the crack propagation path, and the moisture content mainly affects the number of cracks. This research results are valuable for further understanding the tensile properties of rocks and improving the stability of geotechnical engineering.

ZHANG Fu-guang , NIE Zhuo-chen , CHEN Meng-fei , FENG Huai-ping

Natural or artificial cementation formed between sand particles can strengthen the liquefaction resistance of sand. Hence, it is significant to investigate the dynamic behavior of cemented sand at the macro- and micro-scale. By introducing an existing three-dimensional (3-D) complete bond contact model into a 3-D distinct element method (DEM) code, a series of undrained cyclic triaxial shear tests on the cemented sand are simulated, where the effects of cementation and cyclic stress ratio are studied. The results show that the inter-particle cementation can restrain the development of axial strain and pore pressure, and increase the liquefaction resistance. In addition, there is an exponential relationship between the cyclic stress ratio and the number of cycles to trigger the initial liquefaction. These findings confirm the reliability of the DEM simulation in this study. When the value of cyclic stress ratio is relatively small, within the cemented specimen with given degree of cementation, a very small amount of bonds break, the mechanical coordination number remains almost unchanged, and the input work is mainly used to increase the elastic energy at the particle contacts and bond contacts. For the cemented sand before the initial liquefaction, as the cyclic stress ratio increases, the inter-particle bonds break more intensely, the mechanical coordination number declines faster. Likewise, as the cyclic stress ratio increases, the elastic energy at the particle and bond contacts tends to zero faster, and the dissipated energy reaches the maximum value in a shorter period of time. In addition, the contact normal orientation tends to be isotropic more rapidly.

van Albada

Journal of Physics: Conference Series II ALL-RUSSIAN CONFERENCE WITH INTERNATIONAL PARTICIPATION Deep foundations and geotechnical problems of territories, DFG 2021 Perm National Research Polytechnical University, Perm; Russian Federation; 26 - 28 May 2021; Editorial Preface(Editorial) Open Access Vatin N.a, Borodinecs A.b, Abdikarimov R.c aPeter the Great St. Petersburg Polytechnic University, St. Petersburg, Russian Federation bRiga Technical University, Riga, Latvia cTashkent Financial Institute, Tashkent, Uzbekistan The current 2nd All-Russian Conference with international participation “Deep Foundations and Geotechnical Problems of Territories” (DFG 2021) was successfully held in Perm, Russia, at the Perm National Research Polytechnic University from May 26 to 28, 2021. A key aspect of this conference is the strong confusion of academia and industry. This allows the free exchange of ideas and challenges faced by these two key stakeholders and encourages future collaboration between members of these groups. The conference was organized by the Perm National Research Polytechnic University, the Russian Academy of Architecture and Civil Engineering, and the Russian Society of Soil Mechanics, Geotechnics, and Foundation Engineering. The main goal of the conference is to promote research and development in advanced research in the field of geotechnics, and the other goal is to facilitate the exchange of scientific information between researchers, developers, engineers, students, and practitioners working around the world. The conference model was divided into four sessions, including oral presentations and keynote speeches from invited speakers. Key reports were presented by leading experts from France, Germany, Russia, Italy, Turkey, Kazakhstan, and Uzbekistan. The speeches were accompanied by a simultaneous translation and lasted up to 40 minutes. Then the work continued in four sections, where the speakers were given up to 15 minutes to speak. The conference included 69 reports from more than 200 authors, as well as 20 poster presentations. The conference was attended by over 100 people, including online. The conference was held in a mixed-mode. Most of the participants took part in the conference directly, the other part was online. The latter was associated with the epidemiological situation in Europe and Russia. Which of course made it difficult to communicate between specialists and worsened the lively climate of communication. Key lectures at the conference were delivered by Professor Zhusupbekov A.Zh. President of the Kazakhstan Geotechnical Association (Eurasian National University, Kazakhstan), Professor E. Guler (Bosphorus University, Turkey); Professor - Manassero M., Vice President of ISSMGE for Europe, Professor (Turin Polytechnic University, Italy); Professor Katzenbach R. (Darmstadt Technical University, Germany); Professor Varaksin S., ISSMGE TC211, (France); Professor of the Prague Technical University I. Vanicek (Czech Republic). During the conference, modern geotechnologies for the construction of foundations and foundations in various soil and climatic conditions, including in potentially dangerous areas, were discussed, as well as modern methods of engineering surveys and testing of newly erected objects. Practical experience of strengthening the foundations of existing buildings and structures. New materials and technologies in road construction are presented. The results of experimental and theoretical research in the field of geotechnics and foundation engineering, methods of modeling, and calculations of foundations and foundations are discussed. The proceedings of the conference are a collection of accepted articles and represent an interesting outcome of the conference. Topics include, but are not limited to, the following areas: laboratory and field testing of soils; experimental and theoretical studies of foundations and underground structures; technology of the device, strengthening of bases and foundations; the practice of development of underground space, geotechnical monitoring, geosynthetics in geotechnics. The exchange of views on topical issues of fundamental structures contributes to the development of geotechnics, strengthening and expansion of communication between experts in the field of soil mechanics and geotechnics in Russia and abroad.

V A Ilyichev, N S Nikiforova, A V Konnov

Abstract The article is devoted to the application of the technological soil mechanics principles in the design and construction of underground structures, also in problematic soils – loose water-saturated sands. The definition of technological soil mechanics is given. The relevance of the research topic is justified. A quantitative assessment of the stress strain behavior (SSB) of the soil mass containing the support systems of deep pits, depending on the technology and sequence of work during underground construction, was made. The possibility of the SSB of ground mass managing during underground construction in order to select the most economical options for design and technological solutions is proved. Recommendations for SSB management of underground parts of buildings and structures, as well as the surrounding soil mass, based on the technological soil mechanics application are formulated.