Settlement Formula Research Articles

Estimation of the settlement of pile head using ANN and multivariate linear regression based on the results of load transfer method

Abstract Artificial neural networks, machine learning, and data preparation are normally implemented in a wide range of real-world problems, especially in geotechnical applications with optimistic prospects of accurate procedure outcomes. This technique has been utilized to precisely predict the top settlement of piles with various piles and soil parameters. Generally, the pile settlement is an essential requirement to produce a secure structure and has high-performance services. The current article presents the fitting of the artificial neural network (ANN) outcomes by calculating the coefficient of correlation R 2 between the predicted and the measured or calculated value of pile settlement. The ANN algorithm is developed using Python 3.9 IDLE and open-source libraries such as Keras, sklearn, Numpy, matplotlib, pandas, and Tensorflow. Because of random training and test performance, the model has been run at least ten times. The ANN model score and R 2 are compared for all runs in the testing phase. The higher score and R 2 values are chosen. Moreover, the Multivariate Linear Regression with the sklearn library is also offered in this article and utilized to produce a pile settlement formula by applying the same dataset used in ANN. The score and R 2 for choosing the first run of the ANN are 99.95% and 0.9631, respectively, while the correlation coefficient for the Multivariate Linear Regression in the training and testing phases is 0.972 and 0.919, respectively. Both techniques illustrate considerable results.

Deformation Prediction Model of Existing Tunnel Structures with Equivalent Layered Method–Peck Coupled under Multiple Factors

The existing tunnel structure, the new underpass tunnel structure and the rock strata in the area of influence of the crossover tunnel are interacting systems that are affected by various factors, such as dynamic and static excavation loads and dynamic and static train loads. The existing theoretical models for the deformation prediction of existing tunnels lack the synergistic analysis of dynamic and static loads on both existing and new tunnels. Based on the theory of the current layer method and Peck’s empirical formula, this paper considers the stiffness of existing tunnels, the stiffness of new tunnels, the loads of excavation methods and the loads of existing tunnels. The results show that a theoretical model for the prediction of the deformation of double-lane highway tunnels underneath existing railroad tunnels with the coupling of the current layer method and Peck under multiple factors is constructed; a modified Peck settlement formula for the base plate of the existing tunnels is put forward; and, through numerical calculations and monitoring data for validation and optimization, it is proved that the theoretical model is applicable to the excavation of tunnels underneath mountainous areas mined by the blasting method.

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.

Influence of double-line large-slope shield tunneling on settlement of ground surface and mechanical properties of surrounding rock and segment

The surface settlement formula of large slope tunnel is derived firstly. Then, the finite element model of shield tunnel is established by using ABAQUS software. Finally, the influences of tunnel slope, grouting pressure and shield tail clearance on ground surface settlement, and mechanical properties of surrounding rock and segments are studied by the field measurement and numerical simulation method. The results show that (1) For the slope is less than 4°, the slope increases by 1°, the settlement of ground surface increases by about 2.85 %, the shear stress of surrounding rock increases by about 4.5 kPa, and the tensile and circumferential stresses of segment increase by about 5 % and 3.1 %, respectively. (2) The proper grouting pressure is beneficial to the settlement of ground surface, and the mechanical properties of surrounding rock and segment. (3) For the shield tail clearance is less than 15 cm, the clearance increases by 1 cm, the settlement of ground surface increases by about 0.65 mm, the shear stress of surrounding rock increases by about 4.77 kPa, and the circumferential stress of segment reduces by about 0.02 MPa. Therefore, the grouting pressure with 200 kPa and the shield tail clearance with 10 cm are recommended.

Approximate analytical solution of tunneling‐induced responses of a soil–foundation system using contact mechanics

AbstractEstimating the tunneling‐induced responses of a soil–foundation system is crucial for safety control in urban underground engineering. In existing analytical research, the soil–foundation interaction is considered based on the Winkler soil model, with minimal focus on the continuum soil model. Hence, in this study, based on the continuum soil model, an approximate analytical solution is derived to predict the tunneling‐induced responses of a soil–foundation system considering the contact effect, where an approximation by replacing the surface of the complex variable solution for an elastic half‐plane with a tunnel with the mathematical expression of Sagaseta's ground loss settlement formula is adopted. A new strategy is proposed to optimize the derivation process, where the normal contact pressure after tunnel excavation is directly determined using the contact mechanics, and the proposed solution is obtained using the superposition principle. Subsequently, the approximation is proven to be accurate when the ratio of the buried depth to the tunnel radius is greater than 2.00. The proposed solution meets the given conditions and is in good agreement with numerical results, which verify the correctness of analytical solution. Furthermore, a parametric study is performed to investigate the influences of the key parameters on the mechanical responses. The results indicate that the proposed solution can quantitatively describe the nonlinear contact characteristics in the soil–foundation system; the contact effect is found to contribute to the discontinuous displacement and stress concentration when subjected to the significant effects of tunnel excavation.

EVALUATION OF THE PILE BEARING CAPACITY IN ROCK INTERBEDDED BY COHESION SOILS UNDER VERTICAL LOADING

Introduction . The current regulatory calculation procedure for piles in rocks provides a means to determine the bearing capacity of a pile embedded in a solid rock mass containing no weak interlayers. However, it is not uncommon in actual design practice for rocky soils to be interbedded with softer and less stiff dispersive soils, whose presence affects pile performance. In this case, a summation of estimated resistances along the pile length and at its foot overestimates its estimated bearing capacity, which does not correspond to the actual work due to the different rates of friction force generation in soils of varying formations. Aim . To develop a procedure for determining the bearing capacity of a single bored cast in place pile interacting with rock mass interbedded with cohision soils under vertical indentation loading. Materials and Methods . The procedure for estimating the skin friction resistance of a pile penetrating rocky and dispersive soils is based on the analysis of static pile tests and numerical simulation, taking into account tabulated and analytical solutions given in regulatory literature. Results . A procedure for determining the bearing capacity of a single pile interacting with a rock mass interbedded with cohision soils was developed using tabulated solutions given in regulatory literature, empirical dependencies, and numerical simulation. As a criterion for the ultimate shear resistance of bearing soil, a formula for reference settlement S ref is proposed, which factors in pile dimensions and the characteristics of the pile shaft material. The extent to which the pile bearing capacity is sensitive to the parameters of the model and computational assumptions of numerical modeling is analyzed. The presented examples of determining the design pile bearing capacity via the proposed procedure show results similar to experimental data obtained in the field tests. Conclusions . The presented method allows engineers to factor in the skin friction resistance of cohision soil interbedding in the rock mass to increase its design bearing capacity.

Тактика малых шагов в урегулировании конфликтов: казус Приднестровья

The article analyzes the phenomenon of the small steps tactics in the peace process. An attempt is made to demonstrate how the systematic interaction of the parties to resolve non-politicized issues allows either to avoid another "freeze" of the negotiation process, or, at least, to maintain an informal dialogue when negotiations are not conducted at the political and diplomatic level. This approach is adjacent to the Track II diplomacy or one-and-a-half track diplomacy, as well as to the concepts of sustainable dialogue and confidence building measures. Reconciliation and finding a reliable formula for settlement is impossible in cases of protracted and smoldering conflicts without creating a sufficient level of mutual trust, at least between those social groups of representatives of the parties who form the political agenda and who are at the negotiating table. The study allowed the author to identify the similarity of confidence building measures and the "small steps" tactics, as well as conceptual differences that allow us to talk about its innovative nature. The article reviews the positive narratives of the "small steps" tactics and identifies limitations for its application. For this purpose, archival documents of the negotiation process, reports of the OSCE and foreign ministries of the parties to the conflict, statements of the involved participants, as well as the personal experience of the author, who was involved for a number of years in the negotiation process on the Transdnistrian settlement in the "5+2" format. The paper concludes that the "small steps" tactic is not able to resolve the conflict or build a settlement model, but, thanks to the principle of mutual security of behavior models, it makes it possible to achieve a change in the relations of the parties to the conflict, to transfer them from confrontational to cooperative, thus influencing the situation in the conflict zone.

Model Test and Theoretical Analysis of New and Old Embankments Differential Settlement Considering Lateral Deformation

In the embankment widening project, the new embankment will produce large deformation due to the low degree of consolidation, which will affect the stability of the embankment. Obtaining the settlement law of embankment is the premise to ensure the stability of the embankment. In this paper, the deformation law of the new embankment is studied through the embankment model test, and the settlement calculation method of the new embankment is proposed. The model test results show that the new and old embankments have a large settlement difference during the loading process, and the maximum settlement of the new embankment is twice that of the old embankment. The lateral deformation of the new embankment is directly proportional to the vertical deformation, sliding occurs under the ultimate load, and the bearing capacity is lost. Based on the one-dimensional calculation method, the lateral deformation coefficient is introduced, and the two-dimensional embankment settlement formula is obtained. The new embankment is meshed, and the deformation of each node is calculated by the formula, and the difference between the settlement and the model test data is 6.2%, which proves the feasibility and accuracy of the calculation method.

Modified Formula for Settlement of Reinforced Ground with Floating Soil-Cement Columns

Abstract Low improvement ratio soil-cement columns adopted in ground improvement are cost-effective with less environmental impact. However, the settlement mechanism of the reinforced area has not been clearly established, and the traditional settlement estimation formula only treats the reinforced area as an elastic block. Settlement of the reinforced area for a soft foundation with low improvement ratio soil-cement columns was investigated by conducting a series of 1-g model tests. By reconsidering the effect of column length, the traditional formula was modified by adopting a stiffness ratio with the function of capturing the effect of skin friction between the column and surrounding soils.

Analysis of Stratum Settlement Laws Caused by the Construction of Shallow-Buried Expressway Tunnels with Large Span and Small Spacing

Many tunnels with large spans and small spacing have been constructed due to the rapid development and construction of China’s expressways. The stratum settlement caused by the construction of these tunnels in shallow sections is large and difficult to control, and ensuring stratum stability is a key issue in the construction of expressway tunnels. According to the research differences in the prediction of stratum settlement under the tunnel construction at present, based on stochastic medium theory, in this study, the prediction formula for stratum settlement in the construction of double-line tunnels was revised and optimized by monitoring the construction of expressway tunnels with large spans and small spacing in shallow sections. The accuracy of the revised formula was verified by comparing it with on-site monitoring data. A numerical calculation method was also used to select effective deformation control measures. Results showed that the revised prediction formula of stratum settlement could roughly predict the position and shape of the settlement tank and reflect the uneven settlement caused by the mutual influence of double-line excavation. The accuracy of stratum settlement prediction was high. Moreover, reasonable grouting could effectively reduce stratum settlement. A reasonable grouting plan should be selected during construction in accordance with the actual situation to avoid material wastage and increased costs caused by excess grouting.

Formula for predicting ground settlement induced by tunnelling based on Gaussian function

A formula for the variation of the maximum ground settlement with the depth above a tunnel is proposed based on data from 25 field project cases and 10 model test cases. The Gaussian function is developed by introducing the proposed formula and an existing formula for settlement trough width coefficient, to predict the settlement above the tunnel in the transverse section. There are two parameters, n and k, in the developed Gaussian function, and determination methods of the new parameter n are provided for clay strata and sand strata, respectively. The application method of the developed Gaussian function is demonstrated by a field project case. Finally, applicability of the formula for the maximum ground settlement and the developed Gaussian function are validated by 12 field project cases and 9 tunnelling model test cases conducted by the authors.

A new model to predict ground surface settlement induced by jacked pipes with flanges

Ground surface settlement is one of the critical parameters that needs to be controlled strictly during pipe jacking. The calculation model for estimating the ground deformation induced by pipe jacking is scarce in the literature, especially for pipes with irregular cross-section (e.g., circular pipes with flanges). In this study, considering the pipe-soil interaction, the distribution characteristics of frictions between pipe and soil, and the support force at the tunnel face, a settlement formula is proposed for a single jacked pipe using the Mindlin’s solution and the Stochastic medium theory. Based on the cavity expansion theory, a relationship for calculating the circumferential plastic zone is developed considering the effect of flanges. The distribution of the plastic zone around the pipe and the superimposition effect due to multiple pipes are discussed. Finally, a correlation is established to estimate the ground surface settlement for three types of multiple jacked pipes with different spacing. A case study of a subway station project using the Steel Tube Slab (STS) method is presented. Comparisons of ground settlement from field measurements and theoretical calculations show that the proposed approach can reasonably predict the ground surface settlement for multiple jacked pipes.

Asymptotic analysis of natural frequencies of axisymmetric oscillations of orthotropic cylindrical shells in an infinite elastic medium, liquid filled

Aim of the research. Free axisymmetric fluctuation of a cylindrical orthotropic cover, the infinite length contacting to the infinite elastic medium and filled with liquid is investigated. Methods. At design of the thin-walled shell designs which are widely applied in aviation, the missile and space equipment and various fields of the industry, an important task is dynamic calculation of the intense deformed condition of these designs. At a research of dynamics of covers it is necessary to determine own frequencies and forms of small fluctuations, and frequencies from the lower part of a range are of the greatest interest. It is supposed that the rigidity of material of a cover is a little more than rigidity of material of the environment. The solution of the equations of movements of the environment is considered in two options. Results. The frequency equation is received. The analysis of frequency and a form of fluctuations of a cover is carried out. The schedule of dependence of frequency of own axisymmetric fluctuations of a system on wave formation in the longitudinal direction is constructed. By means of an asymptotic method the frequency equations of the ridge cylindrical covers filled with liquid are constructed, the approximate frequencies of the equation and simple settlement formulas allowing to find values of the minimum own frequencies of fluctuations of the considered system are received, the forced fluctuations of the supported cover filled with liquid are investigated and defined is amplitude frequency characteristics of the considered oscillatory processes.

Assessment of the effect of atmospheric pressure on the level and ground waters flow

The problem of understanding the interaction of river and ground water waters is intimately bound to questions of formation and unloading of ground waters in river network. The analysis of the previous researches showed that change of atmospheric pressure affects on the water level in observation wells and water discharge of springs. However, the mechanisms of this influence still weren't completely opened. For the solution of this task the complex laboratory, field and theoretical researches including overseeing by a drain, ground water level, atmospheric pressure and air pressure in an unsaturated (vadose) zone were conducted. On the basis of the conducted researches regularities the connecting size of change of ground water level and a drain of ground water waters with atmospheric pressure were received. As a result of generalization field and laboratory researches it was shown that the crucial role in formation of these regularities is played by the area located over a mirror of ground waters with the isolated interstitial air.With an increase in atmospheric pressure, the volume of interstitial air decreases, and at pressure drop volume increases. It, in turn, leads to change in the level and a flow of ground waters. The settlement formula for numerical assessment of variability of level ground depending on atmospheric pressure (barometric efficiency) and degree of air isolation was received from it in an unsaturated zone. As an indicator of isolation, a characteristic is used such as the volume of interstitial air involved in the inflow (outflow) of water into a measuring well or watercourse and not having direct contact with the atmosphere. Research results showed that, in addition to gravitational force in the movement of ground water and the formation of ground water inflow of rivers and lakes, another force plays a certain role - the pressure difference between atmospheric air and air in the unsaturated zone above the aquifer.

Footing settlement formula based on multi-variable regression analyses

The formulas offered so far on the settlement of raft footings provide only a rough estimate of the actual settlement. One of the best ways to make an accurate estimation is to conduct 3-dimensional finite element analyses. However, the required procedure for these analyses is comparatively cumbersome and expensive and needs a bit more expertise. In order to address this issue, in this study, a raft footing settlement formula was developed based on ninety finite element model configurations. The formula was derived using multi-parameter exponential regression analyses. The settlement formula incorporates the dimensions and the elastic modulus of a rectangular raft, vertical uniform pressure and soil moduli and Poisson\'s ratios up to 5 layers. In addition to this, an equation was offered for the estimation of average deflection of the raft. The proposed formula was checked against 3 well-documented case studies. The formula that is derived from 3D finite element analyses is useful in optimising the raft properties.

The Choice of Effective Geotechnologies to Ensure the Preservation of Historic Buildings During Their Renovation with the Underground Space Development

The research was conducted on the effectiveness of modern geotechnologies providing minimal soil mass deformations under historical buildings and monuments renovated with underground part development. Analysis of the worldwide experience in renovation of historical buildings and architectural monuments revealed trends in application of geotechnologies concerning underground part development. As a result of numerical experiments with a use of PLAXIS and MIDAS GTS software conducted in 2D and 3D for Moscow typical geology conditions and on-site deformation measurements during renovation of historical buildings with underground part development the method for the settlement prediction at the initial phase of design was proposed. For engineering calculations the graphical interpretation is presented describing the settlement formula for buildings with foundations underpinned by jet piles during the underground floor construction. Recommendations have been done for applying geotechnologies in renovation of historical buildings and monuments with underground part development.

МЕЖДУНАРОДНО-ПРАВОВАЯ БАЗА СИРИЙСКОГО УРЕГУЛИРОВАНИЯ

The article compares elements of an internationally recognized basis for the Syrian crisis settlement. The latter is comprised of documents adopted during discussions in the framework of various international formats: Kofi Annan Plan (2012), Geneva Communique (2012), United Nations Security Council Resolution 2254 (2015). The paper analyses the nature of Russian-American differences in interpretation of the three documents provisions as well as links between those decisions and various collective formats including UN Security Council, Action Group for Syria and International Syria Support Group (ISSG). The author looks into negotiation process to which these documents served as a basis, first and foremost intra-Syrian talks in Geneva, and specifies Russian and American positions on the issue of the so called political transition in Syria; identifies strong and weak points of relevant decisions, and contemplates if they could be used as an effective instrument of collective search for a Syrian conflict settlement formula. Syrian authorities’ stance towards these documents and decisions is also analysed, as it defines the behavior of the Syrian government delegation at intra-Syrian talks in Geneva under the UN auspices. The article explains why Damascus did not find acceptable provisions of the internationally-agreed document and refused to perceive them as a basis for the Syrian crisis solution.&nbsp

Comprehensive group pile settlement formula based on 3D finite element analyses

In the past, formulas for the settlement of group piles considered only a few input parameters and offered only a limited approximation of the actual settlement. Nowadays, however, thanks to the fast-growing performance of personal computers, it is possible to create large 3-dimensional finite element models with a better and more reliable settlement approximation. On the other hand, 3-dimensional finite element methods for piles are not very common in practice since the required procedure is comparatively cumbersome, expensive and needs a bit more expertise. In order to address this issue, a pile settlement formula was developed in the present study based on about 120 finite element model configurations. The group pile settlement formula incorporates the dimensions of a rectangular raft, namely, the diameter, length and spacing of the piles, vertical uniform pressure, soil moduli up to five layers, ultimate pile-soil resistance, pile-tip resistance and elastic modulus of the piles. In addition to this, the average deflection rate of the raft is estimated. The reliability of the finite element model is verified through laboratory-scale group pile tests. The proposed formula is also checked against five well-documented case studies. The formula may help engineers optimize group pile configurations more efficiently by applying the quality of the 3D finite element estimation to practice.

Simplified analysis about horizontal displacement of deep soil under tunnel excavation

Most of the domestic scholars focus on the study about the law of the soil settlement caused by subway tunnel excavation, however, studies on the law of horizontal displacement are lacking. And it is difficult to obtain the horizontal displacement data of any depth in the project. At present, there are many formulas for calculating the settlement of soil layers. In terms of integral solutions of Mindlin classic elastic theory, stochastic medium theory, source-sink theory, the Peck empirical formula is relatively simple, and also has a strong applicability at home. Considering the incompressibility of rock and soil mass, based on the principle of plane strain, the calculation formula of the horizontal displacement of the soil along the cross section of the tunnel was derived by using the Peck settlement formula. The applicability of the formula is verified by comparing with the existing engineering cases, a simple and rapid analytical method for predicting the horizontal displacement is presented.

Settlement of Soft Clay Subgrade Under Coupled Effects of Vibration Frequency and Dynamic Stress Ratio Caused by High-Speed Train Loads

Settlement regularity of soft clay subgrade under cyclic principal stress rotation caused by high-speed train loads is investigated. In laboratory tests, it is found that, with increasing vibration frequency at a fixed dynamic stress ratio, the increase of axial plastic cumulative strain in saturated soil is restricted at mid-high frequencies (0.5-2 Hz), and the changes in pore-water pressure are not evident. Combined with the empirical settlement formula and analysis of the dynamic amplification equation of German standard, a simplified settlement calculation method accounting for resonance is obtained.