Settlement Values Research Articles

Stress-Strain State Assessment of Building Subfoundations Having Flexible Constructive Scheme in Irregular Soil Stratification

Introduction. One of the main problems in the operation of buildings and structures is possibility of their damage due to non-uniform deformation of subfoundation soil caused by the various natural and technogenic factors. To establish the possible character and degree of damage of the above-surface structures, it is necessary to calculate the value of subfoun- dation relative differential settlement at the level beneath the foundation bottom. The subfoundation settlement is calculated within the compressible soil thickness using the specific gravity values and soil deformation modulus. The increment of settlement is induced by the increase of vertical stresses in the massif and increase of soil deformability upon growth of moisture. The purpose of the study is to establish the dependence of the magnitude of the relative difference in settlement on the deformation properties of soils with uneven occurrence of layers in order to predict the nature of damage to above-ground structures.Materials and Methods. An example of subfoundation deformation calculations at the bottom level of the free-standing foundations of a building having flexible constructive scheme has been studied. A model of stratification of two heterogeneous geotechnical elements with a 1:4 boundary slope and differing physical and mechanical properties has been used. It has been assumed that one of the geotechnical elements has natural properties enabling the building foundations to rest on it without prior site preparation. Another geotechnical element has significantly worse properties. The calculations on determining the settlement have been made in accordance with the layer-wise summation methodology.Results. The regularity in alteration of the predicted settlement value depending on the ratio of firm and soft soils thickness in the irregular stratification has been established. It has been proven that the difference between the specific gravity values of the heterogeneous beds within 10 % does not affect the depth of compressible soil thickness if the calculation of settlement is made using the layer-wise summation methodology.Discussion and conclusions. The calculation results analysis of the subfoundation settlement of the equidistant column foundations was carried out, the engineering solution was proposed to ensure reliability per limit state groups.

BiLSTM for Predicting Post-Construction Subsoil Settlement under Embankment: Advancing Sustainable Infrastructure

The load and settlement histories of stage-constructed embankments provide critical insights into long-term surface behavior under embankment loading. However, these data often remain underutilized in predicting post-construction settlement in the absence of geotechnical subsoil characterization. To address this limitation, the current study integrates bidirectional long short-term memory (BiLSTM) into a three-phase framework: data preparation, model construction, and performance evaluation. In the data preparation phase, the feature vector comprises basal pressure, pressure increments, time intervals, and prior settlement values to facilitate a rolling forecast. To manage unevenly spaced data, an Akima spline standardizes the desired time intervals. The model’s efficacy is validated using observational data from two distinct construction case studies, each featuring diverse soil conditions. BiLSTM proves effective in identifying key attributes from load and settlement data during the staged construction process. Compared to traditional curve-fitting methods, the BiLSTM model exhibits superior performance, robustness, and adaptability to varying soil conditions. Additionally, the model demonstrates low sensitivity to the range of post-construction data, allowing for a data collection period reduction—from six months to three—without compromising prediction accuracy (relative error = 0.92%). These advantages not only optimize resource allocation but also contribute to broader sustainability objectives.

Study on the effect of excavation sequence of three-hole shield tunnel on surface settlement and segment deformation

In order to study the influence of excavation sequence of three-hole parallel shield tunnel on surface settlement and segment convergence, an improved “three-stage analysis method” was proposed to calculate the surface settlement of three-hole parallel shield tunnel. Based on Peck's existing theory, this method deduced the ground settlement formula under the three-hole parallel condition, and can calculate the ground settlement more accurately. Based on the engineering background of a shield tunnel section in Jiangsu Province, a three-dimensional model of a three-hole parallel shield tunnel was established by using Flac3d software, and the three-hole parallel shield tunnel was simulated under four working conditions: right–center–left, right–left–center, right–left–right and right–center (reverse)–left. This paper analyzed the influence of tunnel excavation sequence on surface settlement, soil displacement and deformation of tunnel segments. The construction sequence was optimized based on the above influencing factors. It was found that Case 4, S-type sequential excavation, produced the least ground settlement. The surface settlement value caused by S-type excavation sequence was only 11.41 mm, and the convergence value of the segments generated by S-type excavation sequence was relatively small. Considering the economic factors such as construction efficiency and benefit, the S-shaped excavation sequence was better. The new calculation method of tunnel surface settlement and the optimal sequence of tunnel construction proposed in this paper can provide reference for actual construction.

Analysis of Land Subsidence in Peatlands in the Awareness Area of Pekanbaru, Riau, Indonesia

This study area is administratively located in Parit Indah District, Bukit Raya District, Pekanbaru City, Riau Province. Geographically, the research area is located at coordinates 0° 28' 30.92" N 101° 28' 9.45" E N 0° 27' 25.63" - 101° 29' 47.30" E. The aim of this study was to find out the effect of peat soil types on subsidence. The data collection method in this study was carried out using sieve analysis, water content analysis, specific gravity, subsidence analysis, and soil testing in the laboratory. The effect of peat soil on subsidence has a significant effect between the type of peat and subsidence, the higher the maturity level of the peat, the lower the level of subsidence on peat soil. Based on the study's results, the soil consolidation test with a depth of 75cm-3m had a soil settlement value of 0.467. It is recommended to do this to reduce the impact of subsidence in the land area such as the research area so that it does not have too much impact on the construction which is carried out by hardening the location using the vertical wick drain method, as well as for building foundations it can be done using chicken claw foundation.

The Influence of Ground Water Level Conditions on the Stability of Road Slopes with Retaining Walls

This research was carried out using the P laxis 8.0 finite element method and manual calculations as well as by evaluating the safety factor value. Slope stability analysis using the P laxis program aims to determine the safe value of the slope before and after reinforcement using a cantilever - type retaining wall. Based on the analysis of the P laxis program before the installation of the cantilever retaining wall, in general the condition of the retaining wall on Jalan Ahmad Yani Gg. Batu Mas, Singkawang City experienced a landslide due to the condition of the soil which was classified as having low soil mechanical properties. Slopes with designed cantilever wall reinforcement are considered safer because they have the smallest displacement and settlement values, and meet all slope stability requirements, ie, shear stability is 1.251 > 1.5 (Safe), stability against overturning is 2.415 > 2 (Safe) , and bearing capacity is 0.555 < 0.583. The cantilever retaining wall structure uses D16-100 principal reinforcement and D10-100 shrinkage reinforcement, the base plate uses D16-150 principal reinforcement and D10-100 shrinkage reinforcement.

Settlement Analysis of Ground Surface and Adjacent Building Caused by Driving and Expansion Excavation of Shield Tunnel Using Artificial Freezing Method

The artificial freezing method can effectively improve the stability of strata and provide favorable conditions for the construction safety of shield tunnel in water-rich strata. Based on the frozen shield tunneling project of a metro station, which is close to important buildings, a reasonable freezing method and parameters are proposed in this paper. The simulation model was established by using Plaxis 3D finite element software (Version 2017). The numerical model was verified based on a large amount of field data. The characteristics of segment deformation, ground surface settlement and vertical displacement of buildings were compared between frozen layer and nonfrozen layer during shield tunnel excavation. It was found that segment deformation in the nonfrozen layer is three times that in the frozen layer. The surface settlement above the frozen layer is less than 2 mm. Expansion excavation of shield tunnel was carried out to meet the space function of subway station using artificial freezing method. The deformation of frozen layer was compared between full section excavation and partial excavation. It was found that the deformation of the former is 4.5 times that of the latter, so the partial excavation was chosen as the main research object. Subsequently, the characteristics of vertical displacement and surface settlement of buildings under partial excavation were studied. It was found that the vertical settlement of buildings away from the frozen layer is greater than that of buildings near the frozen layer. All settlement values meet the requirements, thus ensuring the feasibility of partial excavation and ensuring the safety of construction.

Finite Element Analysis on Load-Settlement Behavior of Axially Loaded Pile on Sand

The analysis of geoengineering problems using various constitutive models necessitates substantial field and laboratory research, which entails a significant investment of time and money. As a result, the application of Finite Element Analysis in geoengineering projects is limited. This research focuses on numerically examining the behavior of a pile in a sandy soil layer. The study employs different relationships to estimate soil parameters from standard penetration tests and simple lab tests. These derived parameters, required for the Mohr-Coulomb & Hardening Soil constitutive model and the linear elastic model of the pile, are implemented in the PLAXIS 3D software. This software is used to simulate the settlement of the pile in sandy soil incorporating factors like mesh density and soil-pile interaction. The results of the study reveal that employing a finer mesh size leads to more precise results. Additionally, an interface strength of 67% proves to be more accurate for this study. Furthermore, the correlation introduced by Papadopoulos (1982) exhibits a close relation with field settlement values. In contrast, other correlations either overestimate or underestimate the results. Moreover, the study conclude that Mohr-Coulomb constitutive model satisfactorily predicts the behavior of the pile for the study area.

Assessment of Spatial Patterns of Backyard Shacks Using Landscape Metrics

Urban informality in developing economies like South Africa takes two forms: freestanding shacks are built in informal settlements, and backyard shacks are built in the yard of a formal house. The latter is evident in established townships around South African cities. In contrast to freestanding shacks, the number of backyard shacks has increased significantly in recent years. The study assessed the spatial patterns of backyard shacks in a formal settlement containing low-cost government houses (LCHs) using Unmanned Aerial Vehicle (UAV) products and landscape metrics. The backyard shacks were mapped using Object-Based Image Analysis (OBIA), which uses height information, vegetation index, and radiometric values. We assessed the effectiveness of rule-based and Random Forest (RF) OBIA techniques in detecting formal and informal structures. Informal structures were further classified as backyard shacks using spatial analysis. The spatial patterns of backyard shacks were assessed using eight shapes, aggregation, and landscape metrics. The analysis of the shape metrics shows that the backyard shacks are primarily square, as confirmed by a higher shape index value and a lower fractional dimension index value. The contiguity index of backyard shack patches is 0.6. The values of the shape metrics of backyard shacks were almost the same as those of formal and informal dwelling structures. The values of the assessed aggregation metrics of backyard shacks were more distinct from formal and informal structures compared with the shape metrics. The aggregation metrics show that the backyard shacks are less connected, less dense, and more isolated from each other compared with formal and freestanding shacks. The Shannon’s Diversity Index and Simpson’s Evenness Index values of informal settlements and formal areas with backyard shacks are almost the same. The results achieved in this study can be used to understand and manage informality in formal settlements.

Assessment of the Probability of Exceeding the Limiting Deformations of a Building Foundation

Abstract The level of ground settlement under the effect of certain factors is one of the markers indicating the adequacy of adopted design solutions. By comprehending settlement values, it is possible to infer the degree of risk associated with a project and, if necessary, introduce changes to the design. The concept of reliability management here manifests itself in the timely adjustment of the decisions made, while it is necessary to use the procedure of the quantitative assessment of the probability of the occurrence of a particular limit state. A qualitative assessment indicates only the limits of an area, which approximately characterizes the effects of changes in the geotechnical situation. In this article, a method for determining the probability of exceeding the limit deformation of a building-base massif using the Monte Carlo statistical method is developed, and an algorithm and computer program implementing the proposed calculation method are created.

Reliability of super-slope rack railway under bridge pier settlement

Bridge pier settlement always occurs on the super-slope rack railway, which has serious impact on reliability and stability of rack-bridge system. Aiming at this issue, a coupled dynamic model of the super-slope vehicle-rack(track)-bridge system under pier settlement is established considering gear-rack nonlinear meshing behavior, wheel-rail nonlinear contact behavior and pier settlement. On this basis, the mechanical characteristics of gear-rack system induced by pier settlement are studied. Then, the dynamic influences of two common gear-rack connections (rigid connection and elastic connection) on the adaptability and safety of this system are discussed. Finally, the safety control value of pier settlement of the large-slope railway in mountainous areas is proposed. Results show that pier settlement potentially leads to fracture of gear-rack fasteners under multi-loads such as gear-rack meshing and wheel-rail contact. When the rack and the sleeper are rigidly connected, the maximum shear stress of the fastener is 346.43 MPa when the settlement is 10 mm, which seriously exceeds the standard limit (235 MPa). When they are elastic connected, the maximum shear stress of the fastener is 262.80 MPa, slightly exceeding the limit value. The structural stress of rack is far less than the tensile strength of rack. Under the two connection modes, the maximum deformation of the rack is 14.02 mm and 11.08 mm respectively, which is about 140% and 125% of the pier settlement. The main frequencies of the vibration of the rack are located at 70 ∼ 80 Hz and 65 ∼ 70 Hz respectively. Pier settlement has a significant effect on the stress of the fastener and the deformation of the rack, but has little effect on the vibration and stress of the rack railway.

Study on the consolidation behavior of horizontal drainage foundation under complex aquifer formation conditions in karst regions

Introduction: The consolidation behavior of horizontal drainage foundation under complex aquifer conditions in karst areas is a hot topic in the field of geotechnical engineering.Methods: This paper presents a modified piecewise-linear model for plane-strain consolidation. In this model, the distributed drainage boundary was used to describe the drainage performance of soil layer boundaries, and the UH model considering the time effect was selected to reflect soil’s rheological property. Through comparison with existing research, the validity of the calculation model in this paper was verified. Then several examples were used to analyze the consolidation behavior of the foundation under the combined action of rheological effect and distributed drainage boundaries.Results and discussion: Numerical studies show that the phenomenon of the increase of excess pore pressure exists in the foundation of the distributed drainage boundary after considering the rheology in the early stage of consolidation. Moreover, the larger the secondary consolidation coefficient and the initial over-consolidation parameter, or the smaller the pave rate and the thickness-width ratio, the above phenomenon is more obvious. In terms of the dissipation of the pore water pressure, the larger the secondary consolidation coefficient and the initial over-consolidation parameter, the slower the pore pressure dissipation, and the smaller the pave rate or the thickness-width ratio can achieve the above effects. In terms of the impact on settlement, the above-mentioned parameters are consistent, that is, the larger the corresponding parameter, the larger the corresponding settlement value.

Field-Scale Experimental Study on Thermomechanical Behaviors of Super-Long and Large-Diameter Energy Piles under Liquefied Natural Gas Tank

In this work, field-scale experiments were carried out on two energy piles to investigate the mechanical behavior of the piles when subjected to thermomechanical loads under a liquefied natural gas tank. The results showed that the super-long and large-diameter energy pile exhibited a better heat transfer performance. After pile heating or cooling, the temperature in the mid-depth of the pile increased or decreased rapidly, and at the two ends, the temperature varied relatively slowly. Regarding the observed axial strain, energy pile 1 exhibited predominately compressive deformation during the coupled heating–loading process, while a certain tensile deformation was found near the pile toe of energy pile 2 during the coupled cooling–loading process. Moreover, for both energy piles, positive shaft resistances appeared predominately under both the pure mechanical and coupled thermomechanical conditions, and occasional and local occurrences of negative resistances could be related to the ground conditions on site. The settlement and bearing capacity values of the two energy piles were not significantly affected by the coupled thermomechanical loads, and thus, the serviceability of the gas tank would not diminish.

Numerical Simulation of Karst Collapse in Qingling Town, Wuhan

With background information on the geological conditions of Fenghuo village, Qingling town, Wuhan, based on Terzaghi consolidation theory and GMS software, a hydrodynamic-mechanics coupling model was established. On the basis of simulating the groundwater flow field by GMS software, a mechanical calculation program was developed, and the coupling simulation of hydrodynamic mechanics was achieved. The results showed that the stress state, vertical deformation, and damage of soil are closely related to the underground water flow. The soil pressure value and effective stress value are relatively low from July to August every year. It is the result of buoyancy produced by groundwater. Soil settlement generally occurs in the dry season. When the load is not considered, the deformation value of soil settlement is generally less than 6 mm. In the wet season from July to August every year, the soil will float up, and the floating value is less than 4 mm. The groundwater table changes frequently, and the destruction around the cave body eventually leads to karst collapse.

Analysis of Geosynthetic – Reinforced Stone Piles – Supported Embankments

The low bearing capacity, high compressibility, and lack of lateral resistance of stone pile-supported embankments on soft clay deposits pose design challenges. To overcome these difficulties, geosynthetics have been widely favored by geotechnical engineers in recent years. A two and three dimensional (2D, 3D) finite element model study that simulates a geosynthetic-reinforced and geosynthetic-encased stone pile-supported embankment on soft ground is presented in this paper. To study the effect of reinforcement and encasing on the vertical displacement of stone piles and soft soil, numerical analyses are performed. The results show a significant reduction in settlement with the casing, which is believed to be a direct result of the additional containment pressure created by the geosynthetic casing. With the help of soil reinforcement, the surface settlement values ​​of the soft soil could be significantly reduced.

Deformation Analysis and Reinforcement Effect of Tunnel Pile Excavation of a Subway Station in a Weak Stratum

The underground hole pile excavation method causes a large vertical displacement in a weak stratum, which affects the safety of structures. For the first time, the hole pile excavation method is being used to construct a subway station in South China, and the settlement law of the area is not clear. It is important to clarify the deformation law of the hole pile excavation method in weak strata and the effect achieved by appropriate reinforcement measures. In this paper, by establishing a three-dimensional finite element model of the structure–soil contact element and combining it with the field monitoring data, the law of surface settlement caused by the hole pile excavation method with different thicknesses of the weak stratum has been studied. In order to improve the stability of the surrounding rock and reduce the vertical deformation of the surface, the Metro Jet System (MJS) is used to form inclined piles in the area of large surface deformation, and the effect after reinforcement was evaluated. The results show that as the weak layer thickness ratio increases, the surface settlement also increases. In the case of no reinforcement, a vertical settlement of 116 mm can be achieved when the thickness of the weak layer is 14 m. The vault of the tunnel is in the weak layer and the deformation is obvious. When the vault is not in the weak layer, the settlement is obviously reduced. After MJS pile reinforcement, under the action of soil extrusion, the self-stability of the surrounding rock is strengthened, and the oblique jet grouted pile forms a stable ‘triangle’. The vertical settlement value is basically stable at around 30 mm, which meets the requirements of the regulations. If the tunnel is not reinforced, the self-stability of the surrounding rock above the tunnel arch is poor and the maximum settlement is at the surface. After MJS reinforcement, the maximum settlement is at the vault. The vertical settlement of the ground surface can be effectively controlled by using the MJS pile forming technology in the middle of the tunnel pile driving method.

Influence of Heterogeneous Foundation on the Safety of Inverted Cone Bottom Oil Storage Tanks under Earthquakes

In order to study the mechanical properties of inverted cone bottom oil storage tanks under earthquakes when the foundation is uneven, finite element modeling calculation for a 20,000 m3 storage tank is carried out based on ANSYS Workbench. Wind load, hydraulic pressure load, and seismic load are all equalized as distributed loads with varying spatial positions. Considering various combinations of different heterogeneous foundations and seismic loads, and by adjusting the preset foundation bed coefficient, the final foundation bed coefficient and the maximum foundation settlement value when the equivalent stress of the tank floor reaches yield strength under different conditions are calculated. The results show that under the condition of heterogeneous foundation stiffness considering seismic action, when the coefficient of local foundation bed is higher than that of natural silty clay, the requirement for safe use of the inverted cone bottom storage tank can be met. Among the seven simulated heterogeneous foundation forms, the form with high foundation stiffness on the windward side has a great influence on the safety of storage tanks.

Study on the Mechanical Response of a Dense Pipeline Adjacent to the Shallow Tunnel

This paper aims to address the issue of disturbance caused by excavation tunnel construction on nearby dense pipelines. Relying on the actual project of Nanchang Metro, the three-dimensional finite element numerical simulation method is used to establish a multi-condition numerical model. At the same time, key influencing factors such as the clear distance, intersection angle, surrounding rock parameter, and construction method are considered. The mechanical response of the dense pipeline adjacent to the dug tunnel was systematically studied, and the influence of key factors on the mechanical behavior of the pipeline was analyzed. The results show that when using the CRD method for construction and grouting reinforcement of the surrounding strata of the tunnel, the maximum settlement of the vault is located at the vault of the right guide tunnel, and the maximum settlement value is located at the bottom of the rainwater pipe directly above the tunnel. The vertical displacement, maximum principal stress, and minimum principal stress of the pipeline are arranged in descending order for the full-face, stepped method, and CRD method. The greater the disturbance to the soil caused by the construction method, the more unfavorable the effect on the pipeline.

Recessed Reinforced Concrete Structures to Strengthen Weak Foundations

Ensuring reliable operation of high-speed lines is an important geotechnical task. To ensure normalized values of settlement of the roadway in the presence of weak engineering-geological elements in the bases, the issues of increasing their bearing capacity are especially relevant. To do this, modern construction has a number of geotechnical technologies, as a rule, these include buried reinforced concrete structures immersed in the ground. ready-made or manufactured in the ground.

The Average Wage in the North-West Federal District: An Assessment of Territorial Disparities on a Settlement Level

Introduction. Effective management of regional socioeconomic development processes is not possible without an objective understanding of impact on the economy exerted by internal territorial disparities. The lack of open data in the official statistics concerning settlements and displaying such a basic indicator as an average wage does not contribute to the task also. For the first time, the suggested solution of the following problem is to use an alternative source of data ‒ Russian form of personal income tax (5-NDFL) tax reports. The goal of the article is to determine territorial disparities between average wages on the settlement level in the North-West Federal District. Materials and Methods. The research covers all municipalities of the North-West Federal District from 2015 to 2020. Average wages in urban and rural settlements, municipal districts and city districts were calculated based on the analysis of 7947 5-NDFL tax reports. A comparison was made with the data from the official statistics. The coefficient of variation and the Gini index were calculated for each area and the North-West District in whole as well as the difference between progressive and regressive types of average wages. Mappings were made for selected municipal areas. Results. Based on the data extracted from 5-NDFL forms, the research suggests a method of average wage calculation in municipalities. The proof is given that the following tax reports can be viewed as an appropriate source of data for determination of income inequality in case of settlements. It is established that territorial disparities in the Federal District have decreased due to the slight growth of average and median wages. Through the example of selected municipal districts, the research displays the existing difference in wages amid urban and rural settlements and also indicates the decisive role of the area center in the consolidated regional scores. Discussion and Conclusion. A comparative analysis of inequality indicators in wages has revealed higher values of territorial disparities at the settlement level. In practical terms, the transition from district values of indicators to settlement values in the state monitoring system makes it possible to increase the objectivity of assessing ongoing processes and improve the quality of managerial decision-making.

Investigation on Bearing Characteristics of Gravity Wharf Rubble-Mound Foundation in Different Influencing Factors

The use of the heavy hammer compaction method can enhance the bearing characteristics of underwater rubble-mound foundations. This is crucial to ensure the safety and stability of port and coastal engineering projects. In the present work, a combination of image-recognition technology, 3D laser scanning technology, a discrete element numerical simulation, and a field test was first utilized to establish riprap particles and reconstruct a discrete element numerical model of a rubble-mound foundation, and then the effects of various influencing factors on the bearing characteristics of the rubble-mound foundation were studied. The main conclusions are as follows. (1) The load–settlement curve of the rubble-mound foundation can be divided into three stages: rapid growth stage, slow growth stage, and failure stage. (2) The ultimate bearing capacity of the rubble-mound foundation is positively correlated with the vibration time and vibration amplitude. The riprap particle size and the foundation thickness have negligible effects on the ultimate bearing capacity of the rubble-mound foundation. (3) When adjusting the vibration time, vibration amplitude, and foundation thickness, the settlement value of the rubble-mound foundation tends to increase as the compactness increases. On the other hand, the effects of factors such as the riprap particle size, riprap particle gradation, and vibration frequency on the compactness and settlement value of the rubble-mound foundation are less significant.