Unconsolidated Research Articles

Analisis Penyelidikan Tanah Box Culvert STA. 4+550 dan STA. 8+575 dengan Sondir Manual Paket I.4 – Pembangunan Jalan Kawasan Industri Terpadu (KIT) Batang

The Government of the Republic of Indonesia is developing the Batang Integrated Industrial Estate (KIT), a national strategic project in the shape of an industrial park. A particularly vital industrial region, the Batang Integrated Industrial Estate (KIT) is situated in the northern economic corridor of Java and has access to the Trans Java Toll Road, the rail network, as well as nearby dry ports and port facilities. In order to connect the roads in the Batang Integrated Industrial Estate (KIT) with district roads and national roads or North Coast roads (Pantura), Package I.4-Road Construction of the Batang Integrated Industrial Estate was constructed. In order to ascertain the pertinent stratigraphic and physical characteristics of the soil on which the construction site was built, a soil investigation was conducted during construction. This process is used to assess whether the soil is stable enough to support the construction of a building. Data will be gathered in the form of soil resistance forces against the sondir or cone layers following an investigation or soil study. The sondir test can also be used to determine the required foundation depth, to precisely determine the original soil's bearing capacity, and to choose the appropriate type foundation to use. Location of Sta. 4+550 has a Box Culvert with sufficient embankment height so that it needs to be replaced as deep as -2.00 meters, while the location of the Box Culvert is at Sta. 8+575 embankment height is higher, it requires analysis of soil bearing capacity and settlement so that the replacement depth and use of mini pile foundation can be determined.

Consolidation Coefficient of Soil Prediction by Using Teaching Learning based Optimization with Fuzzy Neural Network

A key factor in constructing buildings leaning on soft soil is the consolidating coefficient of the soil referred as Cv. It is a crucial lab-measured engineering parameter utilized during the design and verification of geotechnical structures. Nevertheless, experimental experiments take a lot of time and money. In this study, the is projected using Fuzzy Neural Network (FNN) with optimized feature selection using Teaching Learning-based Optimization, estimating Cv as the most crucial step (TLO), which has enhanced the quality of the prediction model by removing unnecessary characteristics and relying solely on crucial ones. The experimental results demonstrate that the projected FNN, followed by the Multi-layer Training algorithm Neural Network (MLP), Impact of changing Optimization (BBO), a support vector regression (SVR), Back - propagation algorithm Multi-layer Training algorithm Bayesian Network (Bp-MLP Neural Nets), has the highest predictive validity for the prediction of (Root Mean Squared Error (RMSE )= 0.379, Mean Absolute Error (MAE) = 0.26, and coefficient of determination r = 0.835). Hence, it can be said that even if all used models perform well in predicting the soil consolidation coefficient, the FNN-TLO performs the best.

PLAXIS 3D numerical analysis of complex geotechnical problems of colossal built heritage

The paper aims to contribute to the preservation of high valuable historic masonry structures and historic urban landscapes through the combination of geotechnical, structural engineering. The main objective of the study is to conduct finite element analysis (FEA) of bearing saturated soft clay soil problems and induced structural failure mechanisms. This analysis is based on experimental and numerical studies using coupled PLAXIS 3D FE models. The paper presents a geotechnical analytical model for the measurement of stresses, deformations, and differential settlement of saturated clay soils under colossal stone/brick masonry structures. The study also discusses the behavior of soft clay soils under Qasr Yashbak through numerical analysis, which helps in understanding the studied behavior and the loss of soil-bearing capacity due to moisture content or ground water table (G.W.T) changes. The paper presents valuable insights into the behavior of soft clay soils under colossal stone/ brick masonry structures. The present study summarized specific details about the limitations and potential sources of error in Finite Element Modeling (FEM). Further field research and experimental analysis may be required to address these limitations and enhance the understanding of the studied soft clay soil behavior. The geotechnical problems in historic monuments and structures such as differential settlement are indeed important issues for their conservation since it may induce serious damages. It deserves more in-depth researches.

Numerical simulations of wave-soil-structure interactions for a subsea cover

Glass-reinforced plastic (GRP) subsea protection covers are widely used to prevent damage to offshore pipelines placed on the seabed from dropped objects, hydrodynamic wave induced loads, and trawling. The light GRP subsea covers could be stabilized by using skirts which penetrate the seabed soil. The dynamic wave pressure acting on the cover will transfer to the cover bottom and the skirt and further influence the pore pressure and seepage flow inside the soil beneath the cover. The present study performs a numerical analysis for the wave-soil-structure interaction (WSSI) of a subsea cover. Two-dimensional (2D) numerical simulations are carried out using an open-source numerical toolbox for modeling the porous seabed interaction with waves and structures under the framework of the finite-volume-method (FVM) based OpenFOAM. The nonlinear waves are solved to obtain the dynamic wave loadings on the cover and the pressure on the seabed. A soil consolidation model is used to provide the initial effective stress in the soil. Then, a one-way coupling algorithm is applied for the WSSI analysis to obtain the soil response in the vicinity of the cover. The distributions of the wave-induced pore pressure, the soil shear stress, and the seepage flow within the seabed are studied and the influences of the wave heights and the skirt lengths are discussed.

Variation of negative vacuum pressure in vertical drains with time and depth under variable well resistance

AbstractMost solutions for the large strain nonlinear consolidation of soils with vertical drains are based on the assumption that the negative vacuum pressure only depends on the depth. In response to the shortcomings of this assumption, a large strain nonlinear consolidation model of soils with vertical drains under vacuum preloading is developed by considering the time‐and depth‐dependent well resistance. By fitting the data under different well resistances, the influence of well resistance parameters on the negative vacuum pressure variation in vertical drains is investigated, and the relevant empirical formulas describing the negative vacuum pressure variation in vertical drains are provided. The results obtained from the empirical formulas are in good agreement with the theoretical results as well as the experimental data, by which the reliability of the proposed empirical formulas is verified. The advantages of proposed empirical model can be identified by comparing it with the conventional model in which negative vacuum pressure is only linearly distributed with depth.

Influence of overconsolidation ratio on hydromechanical behaviour of unsaturated silty soil under various shearing rates

Due to the limited land resources in major cities, reclamation becomes an optimal option to solve this issue, unsaturated soil is often involved in these projects, and the hydro-mechanical behaviour of this type of soil significantly are affected by the stress history and time effect. In this study, the overconsolidation ratio (OCR) effect of unsaturated silt under different shearing rates was studied through a series of constant water content tests. The specimens were under an effective confining pressure of 400 kPa. The samples were unloaded to 100 kPa, and 50 kPa to achieve different values of OCRs (4 and 8). The samples with different OCRs were then dried from saturated state to initial suction = 100, 200, and 300 kPa via axis-translation, and then sheared at three different rates. The results show that higher strain rates led to a higher degree of saturation during shearing under different OCRs. The shear strength increased with increasing shearing rates while the maximum deviator stress decreased when OCR decreased. Higher OCRs resulted in larger volume change during shearing; similar behaviour was observed for increasing rates.

Monitoring land subsidence in the Peshawar District, Pakistan, with a multi-track PS-InSAR technique.

Peshawar is one of the most densely populated cities of Pakistan with high urbanization rate. The city overexploits groundwater resources for household and commercial usage which has caused land subsidence. Land subsidence has long been an issue in Peshawar due to insufficient groundwater removal. In this research, we employ the persistent scatterer interferometry synthetic aperture radar (PS-InSAR) technique with Sentinel-1 imaging data to observe the yearly land subsidence and generate accumulative time-series maps for the years (2018 to 2020) using the SAR PROcessing tool (SARPROZ). The PS-InSAR findings from two contiguous paths are combined by considering the variance over the overlapping area. The subsidence rates in the Peshawar are from -59 to 17 mm/yr. The results show that subsidence is -28.48 mm/yr in 2018, the subsidence reached -49.02 mm/yr in 2019, while in 2020, the subsidence reached -49.90 mm/yr. The findings indicate a notable rise in land subsidence between the years 2018 and 2020. Subsidence is predicted in the research region primarily due to excessive groundwater removal and soil consolidation induced by surficial loads. The correlation of land subsidence observations with groundwater levels and precipitation data revealed some relationships. Overall, the proposed method efficiently monitors, maps, and detects subsidence-prone areas. The utilization of land subsidence maps will enhance the efficiency of urban planning, construction of surface infrastructure, and the management of risks associated with subsidence.

A hydro-mechanical coupled contact method for two-phase geotechnical large deformation problems within the SNS-PFEM framework

This paper proposes a novel numerical algorithm to solve frictional contact problems in two-phase porous media, accounting for the large deformation and interface fluid flow, within the framework of the Stable Node-based Smoothed Particle Finite Element Method (SNS-PFEM). The proposed approach builds on our previous work that was only designed for single-phase large deformation contact problems. Within this work, the hydro-mechanical coupling system is discretized using equal-order interpolation, with a polynomial pressure projection method to eliminate the pore pressure instability. Surface-to-surface discretization is then applied to formulate the contact constraint of the two-phase porous medium. Using the dual Lagrange multiplier approach, a coordinate transformation is introduced to enforce the contact constraint of the solid phase. This transformation is subsequently utilized to develop a new interface fluid element, which serves as a tool to model the fluid exchange behaviour between porous media and contact gaps. Different from existing interface fluid elements, the proposed element is constructed based on the contact algorithm, thereby enabling it to handle non-conforming interfaces and tackle challenges associated with large sliding problems. Furthermore, the proposed method can maintain a well-conditioned system matrix throughout the computation process. These distinctive attributes significantly enhance the flexibility of numerical modelling. Finally, the accuracy and performance of our method are verified through four numerical examples. The results show that the proposed method can effectively simulate various geotechnical problems, including multi-layer soil consolidation, fluid-soil-structure interaction, and geological interface-controlled slope failure.

Numerical Investigation of Two Methods to Reduce the Settlement of a Light-Weight Highway Embankment on Soft Soils

The development of road and highway networks sometimes involves passing through compressible soils of poor quality. Given their mechanical properties as foundation soils, these soils are characterized by low short-term shear strength, expressed by undrained cohesion, which increases during soil consolidation, and are also characterized by significant compressibility, resulting in large-scale settlements when a load is applied to them. Nowadays, there are reinforcement methods that make it possible to execute these structures while limiting the risks of instability. This study consists of the numerical analysis of a light-weight embankment of a highway section built on soft soils. Two reinforcement methods are investigated to support the embankment layers and reduce settlement. Interest is given to the behavior of the soils in place before and after the installation of the adopted reinforcement. The analysis is carried out in such a way as to show the importance of the complete consolidation of the soils in place in the long term, which makes it possible to take into account the dissipation of the pore pressures.

Co-simulation for optimal working parameter selection during soil vibratory compaction process

The working parameters of vibratory rollers have an important effect on the compaction quality. The traditional method of obtaining the best working parameters through field tests is time-consuming and laborious. In order to determine the best working parameters more conveniently and accurately, a mechanical-hydraulic-finite element co-simulation method is proposed in this paper. This method considers the effect of the hydraulic system on vibration compaction and makes the simulation result as close to the actual condition as possible. By analyzing the change of soil stress and settlement, the effect regulation of working parameters on compaction quality is obtained. The results show that the proposed co-simulation method can accurately reflect the real conditions, and the best compaction quality can be achieved when the walking speed is 3 km/h, the vibration frequency is 24 Hz, and the amplitude is 2.5 mm. The research provides a reference for improving the compaction quality and compacting-related simulation.

Hydrate reservoir deformation under multi-well strategies based on the dynamic elastic modulus relationship

In order to demonstrate the safety of the multi-well mining method, stratum deformation using multi-well systems is discussed. Firstly, ultrasonic experiments and triaxial tests of hydrate-bearing sediments under different confining pressure and hydrate saturation conditions were carried out. The soil static elastic modulus was compared with the dynamic elastic modulus relationship. Then the dynamic elastic modulus relations were applied to the multi-field coupling model to simulate the hydrate mining process in reservoirs by multi-well strategies. The experimental results show that hydrate saturation impacts the elastic modulus more than the effective confining pressure. In the simulation results, with the increase of the reservoir depth, the soil settlement shows a trend from small to large and then to small. The maximum soil displacement is located at the junction between the hydrate and the overlying layers, regarded as the weak point. In addition, increasing the well branches, expanding the well spacing, and increasing the wellhead radius can increase gas production. However, at the same time, it will also increase the reservoir deformation, thus posing risks to the stability of the formation and extraction wells. On this basis, the efficiency-safety factor was set, and the best mining scheme was determined.

Design and Experiment of Adaptive Profiling Header Based on Multi-Body Dynamics–Discrete Element Method Coupling

To promote the germination of rice panicles during the regeneration season, it is necessary to ensure a stubble height of 300–450 mm when mechanically harvesting the first-season rice. However, due to variations in the depth of the paddy soil and fluctuations in the height of the header during harvesting, maintaining the desired stubble height becomes challenging, resulting in a significant impact on the yield during the regeneration season. This study presents the design of an adaptive profiling header capable of adjusting the height and level of the header adaptively. Based on the theoretical analysis of the profiling mechanism, a quadratic regression orthogonal rotation combination experiment is designed. Considering the actual field conditions, the range of each factor is determined, and simulation experiments are conducted based on the MBD-DEM coupling to establish a mathematical regression model between each factor and indicator. In the case of the profiling wheel linkage length of 562 mm, profiling wheel width of 20 mm, and profiling wheel mass of 3.6 kg, the supporting force of the header on the profiling wheel would be greater than zero, the supporting force of soil on the profiling wheel and the depth of soil subsidence represent the smallest values, and the highest sensitivity and accuracy of the profiling wheel are achieved. Bench tests demonstrated that the header exerts a force on the profiling wheel, confirming the normal functioning of the profiling. The average magnitudes of forces exerted by the soil on the profiling wheel are obtained to be 31.98 N, 31.63 N, and 30.86 N, whereas the corresponding average soil subsidence depths are obtained as 3.4 mm, 5.6 mm, and 8.3 mm, aligning closely with the simulation values. The results indicate that the profiling mechanism achieves high accuracy in ground profiling and that the structural design is reasonable. By employing fuzzy PID control to adjust the height of the header, the average error in adjustment is obtained as 6.75 mm, while the average error in the horizontal adjustment is derived as 0.64°. The header adjustment is fast, offering high positioning accuracy, thereby meeting the harvesting requirements of the first season of ratooning rice.

Multi-data settlement prediction along a road section integrating InSAR and coastal subsurface information with data assimilation

This paper presents a novel approach to examining the impact of soil settlement and its spatial distribution on infrastructure. The study focuses on a specific road section in the Friesland coastal plain in the north of the Netherlands, investigating how the Holocene coastal subsurface architecture influences settlement patterns. Our study underscores the importance of integrating multiple datasets, providing data at varying resolutions. The road segment traverses lithostratigraphical units, which include tidal channel and tidal flat deposits, overlaying an older tidal basin system and intercalated peat beds. Through data assimilation of a settlement model optimized with InSAR measurements, we have identified settlement heterogeneities that can be explained by combining high-resolution variations in lithology with gradual changes in lithostratigraphy. This was accomplished by utilizing a medium-resolution model (MRM) based on borehole descriptions and a high-resolution data (HRD) approach based on cone penetration tests along the road. The HRD method proved more effective in capturing abrupt changes in lithology between channel structures, while the MRM provided a continuous representation of the lithostratigraphic setting of the area. Our study demonstrates that subsurface heterogeneities have significant implications for subsidence along roads. Settlement rates increase from 2–4 mm/year towards 9 mm/year along the road section, resulting in a differential settlement of more than 5 mm/year over a distance of less than a kilometer. This is primarily attributed to variations in lithostratigraphy. Overall, this new innovative approach offers a practical and cost-effective solution for predicting subsidence due to settlement, eliminating the need for expensive laboratory tests. By integrating lithology and lithostratigraphy, more efficient road maintenance and management become possible.

Soil liquefaction and subsidence disaster in İskenderun related to the 6 February 2023 Pazarcık (Mw: 7.7) and 20 February Defne (Mw: 6.4) earthquakes, Türkiye

Soil liquefaction and subsidence disaster in İskenderun related to the 6 February 2023 Pazarcık (Mw: 7.7) and 20 February Defne (Mw: 6.4) earthquakes, Türkiye

Thermal consolidation of layered saturated soil under time‐dependent loadings and heating considering interfacial flow contact resistance effect

AbstractDue to the presence of tiny gaps at the interface of two layers of saturated soil, water seepage occurs at a slower rate within these gaps, resulting in laminar flow at the interface. Based on the Hagen‐Poiseuille law, a general imperfect flow contact model was established for layered saturated soil interfaces by introducing the flow contact transfer coefficient Rω and the flow partition coefficient ηω. The investigation focused on the thermal consolidation behavior of layered saturated soil foundations under variable loadings considering the flow contact resistance effect at the interface. By employing the Laplace transform and its inverse transform, a semi‐analytical solution for the thermal consolidation of layered saturated soil foundations was derived. In the context of a two‐layer soil system, the effects of Rω, ηω, and permeability coefficient k on the consolidation process were examined. The obtained results were then compared with three other interfacial contact models, thereby confirming the rationality of the presented model. The study findings revealed that the flow contact resistance effect leads to a clear jump in the pore water pressure. Furthermore, an increase in Rω and a decrease in ηω were found to significantly enhance displacement and pore water pressure, while having minimal impact on the temperature increment. These insights contribute to a more comprehensive understanding of the thermal consolidation behavior of layered saturated soil foundations and underscore the significance of accounting for the flow contact resistance effect in such analyses.

Multivariate probabilistic assessment of a regional database in Copenhagen

Extensive research has been carried out to establish empirical equations between two geotechnical properties and in spite of the increase in correlation studies, a construction of a multivariate distribution function of more than two parameters is still rare. The objective of this study is to investigate the possibility of constructing two multivariate distribution functions, each consisting of 5 geotechnical parameters based on a) triaxial and soil classification tests and b) oedometer and soil classification tests in stiff over-consolidated clay till from Copenhagen. For this purpose, laboratory measurements from twenty-six sites in Copenhagen are utilized and two multivariate databases are constructed. The correlations among the ratio of deviatoric and mean effective stresses (q/p´), over-consolidation ratio (OCR), secant modulus at reference stress 100 kPa (E50ref), initial void ratio (eo) and liquid limit (LL) are investigated in multivariate model A, while multivariate model B demonstrates the correlations among oedometer modulus at 100 kPa reference stress (Eoed(ur)ref), over-consolidation ratio (OCR), permeability change index (Ck), initial void ratio (eo) and liquid limit (LL). The Nataf transformation model is used for the construction of the multivariate distributions, which are then used to simulate the correlations between geotechnical properties by generating artificial samples. Finally, the artificial samples are compared with the original database for an initial validation of the model. The constructed multivariate models obtained as a result of this study can act as prior for Bayesian updating in multivariate distribution functions when additional geotechnical tests are carried out.

Thermo-hydro-mechanical behaviour of deep Ypresian clays

Investigating the thermo-hydro-mechanical behaviour of deep Ypresian clays (300 to 400 m below ground) is crucial since they are one of Belgium’s potential host rock formations for deep geological disposal of radioactive waste. To this aim, a newly designed and fully instrumented thermal oedometer cell with lateral stress measurement was used to determine the stress state accurately. First, well-preserved core samples were loaded to bring them to the large in situ stresses and reduce the induced matric suction on deep water-undrained sampling. The remaining matric suction was then reduced by soaking with synthetic water of the formation. Next, drained loading and unloading paths were followed to attain different vertical effective stresses at varying overconsolidation ratios (OCRs) before the drained thermal paths (heating and cooling). The results indicated a systematic increase in the horizontal effective stress on heating at constant vertical effective stress. In addition, thermal-induced volume changes in heating/cooling at different OCRs were studied. Test results were finally interpreted within a thermo-mechanical elastoplastic framework.

Modeling of the accurate application of the Kernel Efficiency Method in the proportioning process of shield tunnel construction

Abstract The existing control strategies for subway construction struggle to address the challenges posed by the impact of large-diameter shield-driven underpass subway tunnels on soil settlement. In this paper, based on the mechanism of ground settlement of the shield tunnel under the KNX method, the influence of the underpass tunnel on the existing tunnel and its surrounding soil stress-strain characteristics is calculated by the Peck superposition method. The KNX method is optimized by optimizing the ratio of KNX slurry and the grouting pressure to control the existing tunnel and the ground settlement. The geotechnical general finite element analysis software is being introduced to conduct numerical simulation and engineering application experiments to verify its effectiveness. The results show that when the bonding force of the grouting material is 350Pa-s, the maximum value of the variation is 3.91mm, and the mobility is more suitable, which can effectively fill the void of the shield machine and reduce the settlement of the foundation. When the grouting pressure is 280kN/m2, the maximum contraction of the tunnel is 6.25mm, which can ensure the safety of the existing tunnel on the basis of the tunnel so that the actual settlement of the soil in the tunnel is minimized. Comprehensively, the optimization of the ratio of the KNP method in the control of the deformation characteristics of the soil and structures under the shield tunnel has effectiveness and can effectively provide theoretical and technical guidance for the construction of subway tunnels under the large-diameter shield under the subway.

Subsidence, soil suffusion and their influence on the appearance of cracks on concrete slopes of irrigation canals

The physical and physical-mechanical properties of soils, exceeding permissible hydraulic gradients, rapid filling and emptying of canals, the quality of embankments, linings and others which determine the filtration stability of canals. After completion of construction in the western part at PK47+20, PK202+80, PK218+00, longitudinal cracks appeared in the left slopes. To identify the causes of crack formation, the concrete lining was removed and comprehensive study for the causes of cracks was carried out. Based on the plasticity number, the soils were classified as sandy loams and loamy. The relative subsidence deformation for samples taken from PK 202+80, 218+00 and one sample from PK 47+20 are less than 0.007, those are not subsidence, but the results of second sample taken from PK 47+20 showed from 0.014 to 0.017 which is subsidence soil. The results for the analysis of water samples show the turbidity at PK 185+00 and 218+00, results are 128 mg/dm3 and 11.5 mg/dm3 which exceeds the 6 times than norm, and the results of dry residue are 2026 mg/dm3 and 2030 mg/dm3, which exceed 2 times than the norm.

Field test of compactability of soaked subsidence soil using heavy tamper

Dynamic compaction, including heavy compaction, is a widespread method throughout the world for improving the physical and mechanical characteristics of subsidence and low-density soils. The results of theoretical and experimental studies have established that the depth of compaction and the density of compacted soils depend on the weight, shape of the bottom, the height of the tamper and humidity, the type of structural connection, and the granulometric composition of the compacted soil. This article discusses the results of compaction with a heavy tamper when soaking loess-like subsidence soil, widespread in the city of Darkhan, Mongolia, to optimal moisture.