Hard Soil Research Articles

Direct Shear Testing of Various Hard Soils and Weak Rocks from Greece

Direct Shear Testing of Various Hard Soils and Weak Rocks from Greece

Cyclic response of granular soils evaluated through a strain hardening model incorporated into the generalized plasticity framework

ABSTRACT In this study, constitutive behavior of granular soils is modeled through a generalized plasticity-based theoretical framework. The soil hardening is addressed by a novel relationship proposed to calculate plastic strains and their evolution during loading history. The model is effective in predicting the response and incorporating it into a numerical scheme. Focus is given to stress ratios yielding liquefaction in a few stress cycles. The proposed hardening law is based upon a combined deviatoric-volumetric hardening rule updating the stress-strain relationship and plastic strain vector. Numerous undrained monotonic and cyclic triaxial tests are simulated for verification of the constitutive formulation. Results indicate that the developed model for sand-like cohesionless soils proves to match fairly well with the available experimental data. Plastic strains are calculated accurately and accumulated pore pressures are well captured. Triaxial test simulations exhibit a successfully improved way of capturing the essential static and cyclic behavior of granular soils.

Design of water level detection monitoring system using fusion sensor based on Internet of Things (IoT)

River flooding is a condition when the water in a river overflows and exceeds its normal capacity, thereby flooding the surrounding area. This flood disaster has been a known problem for a long time and causes great damage in the affected areas. Flood events inRivers are influenced by many factors, such as climate change, rapid urbanization, inappropriate land use, ineffective water management patterns, as well as uncontrolled addition of hard soil surfaces. Flood conditions in rivers involve complex processes and are influenced by various factors components, such as rainfall, water flow, topography, vegetation, and many other factors. Therefore, this research is very urgent because it can help reduce the negative impacts of flooding, increase public safety, become a basis for decision making, save costs and resources and make a positive contribution to technological development. This study aims to create a prototype of a flood early warning system. The system is based on a wireless sensor network whose interconnections are connected by a star topology. Every node is a combination of several sensors (sensor fusion) that are related to detecting floods, such as: height sensors, water flow speed sensors and rainfall intensity sensors. Design of hardware (hardware) and software (software) will be done. A classification mechanism based on Fuzzy Logic will be used to estimate flood conditions based on existing data. Flood estimation will determine the time and distance of flood events that will occur. Several experiments in the laboratory will be carried out to determine the performance of the designed system.

Innovative ways to improve machines for preliminary work given the needs of the modern construction industry

The bulldozer-ripper is the main machine during preliminary work. The creation of high-performance machines is carried out in two directions: the production of fundamentally new working elements and machines based on the use of fundamental scientific achievements and the improvement of existing working elements, and traditional type machines that are in operation.
 The creation of working elements for ripper-picks is a perspective development direction of machines designed for ripping frozen and hard soils. They would make it possible to significantly increase the productivity of ripping work through the rational use of the base machine traction force. We applied the superposition principle of the impact on the working medium of several factors concurrently for this, such as static and dynamic loads, through the energy accumulation and its subsequent use to create a high-speed power impulse on the cutting edge to ensure the preliminary formation of the compressed zone in the soil massif. This will lead to the power intensity reduction of the static load on the soil element separation.

Design of precision seeding device based on hexarotor UAV platform and its application in hard soil

Drones, also known as unmanned aerial vehicles (hereinafter referred to as UAV), are widely used in both military and civilian applications, but agricultural drones have made great strides in recent years. Agricultural drones are often used to detect and evaluate crops, aid crop pollination, and spray fertilizers and disperse seeds. However, in terms of seed seeding, the vast majority of drones can only achieve extensive sowing of seeds, and seeds can only be sown on the surface of the soil, and the sowing accuracy of this method is extremely low, and there is a large waste of seeds. In order to improve the sowing efficiency of UAVs and the sowing effect on hard soil, this paper conducts relevant research on the seeding device carried by UAV and designs a new seeding device. On the basis of the traditional spreading function, the device performs design calculation, three-dimensional dynamic feasibility analysis, and is equipped with a precise interval sowing mechanism, which can also send seeds into the deep soil while accurately sowing seeds, which solves the problem of low efficiency of UAV seeding.

Effects of community camel and sheep grazing on vegetation cover in Al-Mayla rangeland in northern Saudi Arabia

The present study was conducted to investigate the effects of community camel and sheep grazing on vegetation cover and production at Al-Mayla rangeland enclosure in Arar, northern Saudi Arabia, protected for 40 years. Following a first vegetation sampling conducted in August 2022, two different sites (Artemisia and Atriplex sites) were identified and management plan involving grazing for one month on the Artemisia site by 769 heads of camels and the Atriplex site by 2739 heads of sheep was proposed. Upon pressure from the pastoral community, the number of sheep was increased to 7500 head and the grazing period was reduced to 2 weeks in September 2022. Field data collection was conducted after grazing. Total plant cover and soil surface states, species cover and density, and biomass available for grazing were measured and compared to the situation before introducing animals. Results showed that long-term protection (40 years) had a negative effect on vegetation cover dynamics through the development of more competitive and stress-tolerant low-range value species and hard soil crust which reduces infiltration, emergence of seedlings, and growth of plants. The findings suggested that short-period grazing with a high stocking density of mixed herds of camel and sheep which reduced animal selectivity and improved soil structure is not harmful to vegetation cover and range production and had social implications by allowing the grazing of more herds from the community

Application of HVSR Method on Microtremor Data for Analysis of Earthquake Potential in Candipuro District, Lumajang, Indonesia

The Earthquake of 6.1 magnitude occurred on April 10, 2021, in Lumajang district. One affected area suffered building losses, road damage, and casualties in Candipuro District, Lumajang Regency, East Java. Then the research was conducted to determine the strength of the soil against the potential earthquake by micro zoning the area in Candipuro District. This research uses the microtremor method with HVSR (Horizontal to Vertical Spectral Ratio) analysis. Analysis of earthquake potential includes parameters of Ground Amplification (A0), Dominant Frequency (f0), Ground Vulnerability Index (Kg), and Ground Shear Strain (GSS). The acquisition was completed with 16 measurement points in Supiturang Village with 500 meters between points using the Portable Seismograph TDS - 303. The results obtained in Supiturang Village have the results of the amplification value factor which is classified as medium-high (2.7 - 8.7), low dominant frequency value (0.5 - 1.4 Hz), medium-high soil susceptibility index (10 - 90), VS30 value which includes medium - hard soil (187.81 - 548.38) m/s, and GSS value which shows the response of cracks and soil subsidence to shaking (2 x 10-5 - 2 x 10-4).

Application of microalgae in wastewater: opportunity for sustainable development

Industrial sustainability is a process that has been gaining space in recent years. The use of microalgae for wastewater treatment could solve some environmental challenges, optimize resources, and generate value-added products in agriculture, biofuel, food, and feed. The use of High Rate Algal Pond (HRAP) presents economic benefits, by treating contaminated effluents and taking advantage of the microalgae biomass generated. The microalgae growth in wastewater can be limited by lighting energy or the easily assimilable carbon source, due to the high load of nutrients and organic matter present in these effluents. In the same way, other physical, chemical, and biological parameters must be controlled to guarantee that the process reaches its maximum performance. The technology applied with microalgae for the waste industrial treatment seeks to generate sustainable, economical, and efficient processes that guarantee the discharge of water under standard parameters that allow for preserving the environment, the quality of life of citizens and generating inputs such as biofertilizers that allow avoiding crucial problems such as NPK ratio imbalance, soil hardening, salinization, nutrient depletion, groundwater contamination and food for animal consumption that allows generating nutritional alternatives. In this way, the treatment of wastewater with microalgae is an opportunity to solve sanitary and environmental problems under a sustainable approach to obtain inputs, although some challenges must be solved for scale production. This document intends to show outstanding aspects related to effluent treatment, water reuse, and sustainable production of agricultural inputs through the use of microalgae.

A thermomechanical model for argillaceous hard soils–weak rocks: application to THM simulation of deep excavations in claystone

The paper presents the enhancement of an existing constitutive model for argillaceous hard soils–weak rocks to incorporate non-isothermal conditions, to be used in coupled thermo-hydro-mechanical (THM) simulations of underground excavations subjected to temperature variations within the context of deep geological nuclear waste disposal. The proposed thermo-elastoplastic extension accounts for the effect of temperature on the yield and plastic potential functions and on the elastic stiffness. The resulting model is validated through the simulation of relevant non-isothermal laboratory tests reported in the literature. The model is then applied to the coupled THM simulation of an in situ heating test conducted at the Meuse/Haute-Marne underground research laboratory in Bure, France, excavated in the Callovo-Oxfordian claystone. Results show that the incorporation of thermal effects into the constitutive description of the host rock plays a significant role in the behaviour of the excavation when subjected to thermal loading, particularly in the evolution of the excavation fractured zone.

Analysis of Ultimate Bearing Capacity of Bore Pile Foundation in High-Rise Building at Pulomas, East Jakarta

<p class="Abstract">Soil condition at the Pulomas tower project site with a water level of 17 m below the ground and the hard soil at ground depth of 18 – 22 m, as well as the project location surrounded by houses and office buildings made the choice of bore pile as the foundation in this project. This condition is the background to the need for a bore pile capacity analysis in this tower project. The objective of this study is to analyze the bore pile capacity which is based on Standard Penetration Test (SPT) and Cone Penetration Test (CPT) and to be compared to the interpretation result of static loading test at a tower project location in East Jakarta. The ultimate bearing capacity of bore pile foundation was calculated using Meyerhof method and Reese & Wright method, and static loading test using Chin method. This study indicated that the ultimate bearing capacity using Reese & Wright method is closer to the interpretation result of static loading test from Chin method compared to Meyerhof method.</p>

A review on compaction and loosening of agricultural soils

Many soil experts and farmers are very concerned about the hard soil layers of agricultural soils. A layer known as hard soil is created when soil is compacted repeatedly over a long period of time. A type of physical soil degradation known as soil hardening modifies soil structure, restricts air and water penetration, and lessens root encroachment. These effects on the crust of the earth are still not fully understood. Therefore, to solve the worldwide dilemma of future food security, a thorough understanding of the subsurface processes is required. Compaction research must also be taken seriously because climatic conditions are shifting as a result of climate change, opening the door for the creation of novel mechanical tillers that can address compression problems. As a result, the focus of this study is on investigating the type, traits, causes, and effects of soil compaction on agricultural production as well as potential remedies using soil tillage.

Influence of excavation depth on the interaction between barrette and subgrade soil (Moscow)

Barrette is a type of piles used in the construction of high-rise buildings on soft soils, as an additional option of bored piles. It is shown that the use of barrettes activates the search for new ways to improve the design quality of foundations, in particular the development of new calculation methods. The paper analyses the computational results of the interaction between long length barrette and subgrade soil at different excavation depths. Methodology: The numerical analysis combined with analogy; numerical simulation based on PLAXIS 3D geotechnical software for the elastic-plastic model of hard and soft soils. Comparison and analysis of numerical simulation data on the barrette interaction and bearing capacity. Findings: Data obtained for excavations of different depths are compared and analyzed. It is evident that piles with greater excavation depth in the considered soil conditions, always have greater bearing capacity and less settlement. The soil bearing capacity can be defined as the barrette load at 40 mm settlement by analogy with in-situ barrette tests. Based on the calculation results, load-settlement plots are given for loading at different excavation depth. It is shown that zones of plastic deformation appear on the lateral surface of the barrette, which is the reason for the settlement growth. Conclusion: The proposed computational model confirms the research results based on the state standard 22.13330.2016 " Building Foundations". The excavation depth affects both bearing capacity and vertical settlement of the barrette. Further research based on numerical calculations and experimental and theoretical data will allow to develop new calculation methods and increase the efficiency of design solutions.

Study on Shock-Absorbing Effect of a Double-Story Isolation Structure Considering Soil–Structure Interaction

The double-story isolation structure is a novel development based on the mid-story isolation structure. To accurately reflect the seismic response of the double-story isolation structure, this study considers a dynamic elastoplastic analysis model that incorporates soil–structure interaction (SSI). Comparative models of a base-fixed structure and a mid-story isolation structure are also established. The results indicate that the double-story isolation structure has a longer structural period compared to the mid-story isolation structure. Furthermore, the structural period increases as the soil softens and the structure becomes more flexible. When considering SSI on hard soil versus not considering SSI, the double-story isolation structure exhibits smaller base shear, story force, inter-story displacement, maximum acceleration of the top floor, and displacement of the upper isolation layer, indicating the significant shock-absorbing effect of the double-story isolation structure. However, when SSI is considered on soft soil, the shock-absorbing effect of the isolation structure diminishes, and the effectiveness of the double-story isolation structure may not necessarily surpass that of the mid-story isolation structure. In all three soil conditions, the compressive stresses of the isolation bearings in the upper isolation layer of the double-story isolation structure were lower than those in the isolation bearings of the base isolation layer. Additionally, the double-story isolation structure demonstrates reduced compressive stress in the isolation bearings, fewer plastic hinges in the frame, and less stress damage compared to the mid-story isolation structure. Consequently, the risk of overturning damage in the double-story isolation structure is significantly reduced compared to the mid-story isolation structure. The effect of soft ground on structures can be highly detrimental, which should be paid more attention to during the design process. This study offers valuable insights for future research on double-story isolation systems and serves as a reference for the development of high-performance building structures in the future.

Sumatra-fault Earthquake Source Variation for Analysis of Liquefaction in Aceh, Northern Indonesia

Introduction: Areas that are situated on active faults experience a severe risk of earthquakes. During earthquake shocks, pore water pressure increases and soil shear strength decreases, resulting in water saturation of the loose sand layer and the possibility of liquefaction. Banda Aceh is a city on Sumatra Island, northern Indonesia, located on active faults that run along Sumatra Island. Aims: To ascertain the liquefaction potential in Banda Aceh City, it is important to conduct a research analysis on the soil profile below Banda Aceh City. This research focused on earthquake acceleration to determine the strength capacity of soil to withstand loads and wave propagation to minimize infrastructure failure. Methods: The liquefaction potential of Banda Aceh was determined by analyzing N-SPT records from three sites using three different approaches. This liquefaction study considered the cyclic loading and seismic acceleration associated with the Sumatra-fault earthquake source, which has a design magnitude of Mw 9.3. Results: The results of cyclic loading showed that Banda Aceh City has liquefaction potential. Using the 3D surface approach, soil profiling gives a cross-vault-shaped soil profile that shows liquefaction potential starting at 2.5 m and the hard soil layer found at 6.0 to 10 m. Conclusion: This study examined the liquefaction potential of Banda Aceh City. The research was carried out using a simplified approach to determine the liquefaction potential index (LPI) at three-dimensional cross faults of discontinuous sand generated by the Sumatra-fault acceleration of earthquake.

Effect of Depth of Water and Container Diameter in Seismic Analysis of R. C. Elevated Circular Water Tank

Safety of water tanks is very important as they are very important life living structures. Tanks shall always be functional for the access to drinking purpose as well as for the requirement of fire fighting in the area of occurrence of earthquake. The study focus on analysis of RC water tank of circular shape in accordance with IS 1893 (Part-2):2014. The analysis of tank is carried out for zones II, III, IV and V and Rocky or Hard Soil, Medium Stiff Soil and Soft Soil conditions in accordance to Indian standard. Further three different depth of water with constant diameter ratios with tank full, half-filled and tank empty condition are considered for analysis. From the analysis, it is found that tank design is governed in full tank condition. Values of seismic horizontal design coefficient in impulsive mode (Ahi) are less than those for convective mode (Ahc), for full tank condition. This is due to lower values of time period in impulsive mode. For the same soil condition, values of Ahi and Ahc increases for higher seismic zone. The values of highest shear and moment at bottom of container are found to be governing in full tank condition as compared with half-filled and empty tank condition.

Remedial Measures to Protect Transmission Tower from Excessive Soil Movement : A Case Study

The research background focused on investigating deformation in the T.73 Nonohonis-Kefamenanu transmission tower structure that was suspected to be caused by soil movement due to the tower’s location on a sloped area. To analyze this, various tests were conducted to examine the soil properties and slope stability considered the impact of intense rainfall. The Cone Penetration Test (CPT) results revealed hard soil at depths of 6.8 meters (S1), 8.4 meters (S2), and 7.4 meters (S3), falling within the Silty Sand to Sandy Silt - Sand zone, with qc > 200 kg/cm2. Boring & N-SPT tests indicated hard soil with N-SPT values > 50 at depths of 18 meters (BH-1) and 8 meters (BH-2). The geoelectrical survey using the Wenner-Schlumberger configuration found a groundwater layer at 3-5 meters and suggested the presence of a slip plane. Janbu’s method was used to analyze slope stability, taking into account the complex profiles, layers, and soil characteristics. Modeling results showed minimum safety factors after rainfall (SF 1 = 1.827) and after 30 days (SF 3 = 3.302) following the installation of a 15-meter bored pile foundation with a 50-ton load at the chimney.

Evaluation of Water Content on the Mechanism of Action of Different Soils

Water content is one of the important physical parameters of soil. In different soils, water content has different effects on their physical and mechanical properties. In the face of the increasingly complex international situation, the study of battlefield activities and support is particularly important. As an important part of the battlefield environment, rock and soil mass elements need to be explored in actual combat. Taking a training ground as an example, this paper collects samples of different soil types and makes mathematical statistics and analysis of laboratory results on the basis of in-situ tests. The research shows that: (1) In soils with relatively low porosity and dense matrix, the moisture content has a delayed effect on the timeliness. With the increase of moisture content, the cohesiveness of the soil increases, while the internal friction Angle decreases. For viscous soil, the moisture content contributes to the shear resistance, while for non-cohesive soil, the moisture content decreases the shear resistance. (2) The sensitivity of different soils to water content is obviously different. In the dense and hard soil area, water content changes slowly and has little influence on the final military-related activities. Compared with the three soils in the area, the sensitivity is in the order of silt > gravel sand > crushed (pebble) stone; (3) In the simulated pre-rain and post-rain training environment, the bearing capacity of soil mass and the damage effect evaluation of the same type of shell in the anti-strike area are consistent with the correlation of soil water content, indicating that under the same environment, the change of different water content will affect the mechanical properties of soil mass itself. (4) Moisture content has a great influence on geotechnical physical parameters, which is an important part of the analysis of battlefield environmental factors, and the research results can guide the design of relevant exercises and training activities.

Seismic Behavior of Colliding Buildings, Incorporating Soil-structure Interaction and Accounting for Variability in Structural Parameters, Soil Parameters, and Seismic Action

Pounding between buildings that are not sufficiently separated has been observed several times during earthquakes. This destructive impact may severely damage the structure and lead to its collapse. Although it is impossible to completely eliminate such losses, measures can be taken to minimize them. This article investigates the effect of the variability of structural parameters, soil parameters, and seismic action on the seismic response of two colliding buildings, taking the soil-structure interaction (SSI) into account. Two adjacent structures closely separated, modeled as inelastic lumped mass systems with different structural characteristics, were considered in this study. Both structures were modeled in the analysis using multi-degree-of-freedom (MDOF) systems, and the pounding was simulated using the modified linear viscoelastic model. The analysis was conducted in two cases: probabilistic analysis and deterministic analysis. Probability curves were established to analyze the effect of the variability of the parameters on the responses of the two colliding buildings. The comparison between the two analyses indicates that the probabilistic analysis is more precise than the deterministic analysis. It has been indicated that taking into account the variability of structural parameters, soil parameters, and seismic action is efficient in determining the realistic behavior of colliding buildings. Additionally, pounding is more critical in the case of buildings founded on very soft soil, followed by those on soft soil, then on hard soil, and finally on rocky soil.

Thermo-hydro-mechanical coupled model of unsaturated frozen soil considering frost heave and thaw settlement

Frost heave and thaw settlement of subgrade is the most typical engineering disease in permafrost regions, which seriously threatens the safe construction and operation of transportation infrastructure. On the basis of the Modified Cam Clay model, a thermoelastoplastic constitutive model of unsaturated frozen soil is proposed. This model can effectively describe two key issues of the mechanical behavior of frozen soils, that is, soil hardening caused by temperature reduction and volume compression during thawing. The proposed constitutive model is realized in the established thermo-hydro-mechanical (THM) coupled mathematical model, and the reliability of the coupled model is verified by comparing with the experimental results. In addition, the proposed THM framework is applied to describe the long-term freezing and thawing behavior of typical railway subgrade sections in the permafrost region of western China. The results show that water-heat transfer and deformation frequently occur on the subgrade surface as the seasons change. Moreover, the variation of thaw settlement is greater than that of frost heave, which seriously threatens the operation safety of railways in permafrost regions.

Macro- and Micro-Characteristics and Mechanical Properties of Xigeda Formation Claystone in Luding County, Western Sichuan, China

Claystone is actually a type of hard soil or soft rock. To reveal the engineering geological characteristics of the Xigeda formation claystone in Luding County (Western Sichuan, China), some experiments, including X-ray diffraction (XRD), scanning electron microscopy (SEM), and geotechnical tests, are performed. The testing results indicate that the Xigeda formation claystone primarily consists of silt, clay, and other fine-grained materials. It is characterized by interbedded yellow and gray thin layers with a horizontal lamination structure. The yellow and gray claystones are made of the same materials but differ in their proportions. Additionally, yellow claystone is characterized by a higher density, resulting in enhanced cementation among clay particles. The permeability coefficient of Xigeda formation claystones ranges from 3.62 × 10−4~7.34 × 10−4 cm/s. The cohesion of yellow and gray claystones decreases with increasing moisture content, and the decline is greater at higher moisture contents. However, the relationship between internal friction angle and moisture content is different. The mechanical properties of the Xigeda formation exhibit significant differences in sensitivity to changes in moisture content across various regions. Notably, the claystone within the study region experiences a particularly pronounced weakening of its mechanical properties when exposed to water.