Horizontal Settlement Research Articles

Analysis of sensor parameters for ultra close range lateral penetration of subway tunnel full section sand layer soil pressure shield tunneling

In order to solve the problem of large disturbance to the stratum caused by shield tunneling in the full face sand layer geology by using the earth pressure balance full bin tunneling technology in the subway tunnel shield construction, this paper presents a parameter analysis of the ultra close side penetration of the full face sand layer earth pressure shield in the subway tunnel. By analyzing the monitoring data of surface settlement caused by subway shield construction, it is concluded that the law of surface horizontal settlement basically conforms to peak settlement theory, and the law of surface vertical settlement basically shows a steady downward trend. Through the mathematical modeling of the cumulative settlement data affected by the shield passing of the right line tunnel at the surface monitoring point, the influence of the shield passing of the left line tunnel on the surface settlement is predicted, and the prediction result is accurate. The experimental results show that the maximum deviation is 1.47 mm and the minimum deviation is 0.03 mm. The prediction accuracy is high and meets the accuracy requirements of practical engineering. Under the same geological conditions and construction parameters, the disturbance law of tunnel shield construction on the ground surface has important guiding significance in practical engineering.

Updating of the seismic fragility curves for RC buildings subjected to slow-moving settlements

The seismic assessment of reinforced concrete (RC) structures is commonly carried out neglecting potential previous damage induced by other phenomena, for example, those related to the actions of slow-moving settlements. Many efforts are dedicated by the research community in properly considering multi-hazard actions and their inter-relations on the structure, instead of a reductionist approach, to be included in the numerical models adopted for the assessment of the seismic vulnerability. Such consequences are increasingly becoming an important issue in the structural assessment, since several structures have an age close to, or higher than, their design life. In this work, a typological 3D case study RC building, chosen to represent gravity loads designed buildings constructed in Italy from the 1950s to the 1970s, is used. The seismic assessment of the building structural elements, caused by the design seismic action, is initially shown. Then, the seismic assessment is repeated, considering as point zero of the analysis the “damaged” building as consequence of slow-moving settlements, acting in different configurations, potentially due to different causes (e.g., landslides, subsidence). A novel comparison in terms of fragility curves is proposed between the safety condition of the building expected in both cases, with or without the consideration of the precedent induced displacements. The effect of the configuration of the previous slow-moving settlements on the seismic response is investigated, by showing that the application of the horizontal settlements has a stronger effect on the penalization of the seismic response of the building, but also the application of the vertical settlements produces a decreasing of the median seismic capacity.

Thrust in a symmetric masonry arch with frictional joints on spreading supports

The effect of a supports settlement in a symmetric masonry arch is studied by modeling the arch as a system of rigid plastic blocks with frictional sliding. It is shown that in a collapse state due to a horizontal settlement the thrust attains its minimum statically admissible value, so extending to the case of frictional sliding a well-known result of standard limit analysis, which considers collapse states only due to the opening of joints. The case of both vertical and horizontal settlements is also analyzed. It is demonstrated that the collapse thrust in case of horizontal settlement is a lower bound for the collapse thrust in case of generic settlement. Extensive numerical analyses illustrate the above results.

Settling velocity of submillimeter microplastic fibers in still water

Microplastic fibers (MPFs) are one of the most important MP contaminants of aquatic environments. However, little research has been conducted on the movement of submillimeter MPFs in water. Herein, the settling of 519 submillimeter MPFs in still water was measured and the settling velocity was analyzed. Observations of the settling velocity of MPFs with lengths of 300, 500, and 600 μm showed that most MPFs settled individually or in pairs. The sedimentation of a single fiber could be divided into three patterns, that is, horizontal, inclined, and vertical. The average settling velocity increased with an increase in the MPFs length and orientation angle. As the MPFs length increased, the probability of inclined settlement decreased but that of horizontal settlement increased. The horizontal velocity of single fibers also was investigated, and the horizontal and vertical settling of MPFs exhibited minimal horizontal velocity. Because of the considerable difference between the calculated drag coefficients from existing drag coefficient models and experimental values, a drag coefficient model was developed with a deviation of <3 %. Four settling patterns were identified for two fibers, that is, X shaped, inverted-T shaped, cross shaped, and overlapping. The average velocity of the overlapping settlement of two fibers was considerably higher than that of the other three settling patterns. The average settling velocity of 600-μm two fibers was 1.47 times that of single fibers, indicating that their corresponding drag coefficient was ~46 % that of a single fiber.

Study on Stratified Settlement and Weak Reflectivity Fiber Grating Monitoring of Shield Tunnel Crossing Composite Strata

This paper proposes a set of field test technology system for layered settlement of composite strata based on weak reflectivity fiber Bragg grating sensing technology based on the shield project of “Keyuan Station ~ Shenzhen University Station” section of Shenzhen Metro Line 13, and through the comparison and verification of three-dimensional numerical simulation and field monitoring, the law and distribution characteristics of disturbance settlement of ground surface and overlying strata during shield tunneling are systematically analyzed, and the vertical and horizontal zoning (layer) system for the spatial and temporal evolution of layered settlement of composite strata during shield tunneling is constructed. On this basis, the targeted settlement control technical measures and recommendations are proposed. The findings show that the weak reflectivity fiber grating sensing technology can better perceive the evolution law and distribution characteristics of vertical and horizontal settlement of composite strata caused by shield tunneling, which is in good agreement with the numerical simulation results, and has the advantages of automation and high precision, it can be used as a supplement and alternative method for traditional measurement methods. The stratum deformation is small and layered settlement is not obvious in shield approaching stage (−5D~0), after shield crossing and shield tail falling (0~3D), the stratum is the longitudinal main deformation zone of shield tunneling disturbance, and the influence range of the whole tunneling disturbance is about (−1D~3D). Meanwhile, according to the influence degree of shield tunneling disturbance, the overlying strata of the tunnel can be divided into main disturbance layer and secondary disturbance layer, and the main disturbance layer is located in the range of 0.5D above the tunnel. In addition, based on the different stages of shield tunneling and the vertical and horizontal zoning (layers) of existing structures such as buildings (structures), the settlement control measures and suggestions are proposed. The research results demonstrate the feasibility of weak reflectivity fiber grating for distributed and continuous strata monitoring. It has important guiding value for improving the understanding of settlement law produced from shield construction in composite strata and analyzing and predicting potential risks resulting from shield construction. It also provides reference value for future subway design and construction.

Settlement of masonry barrel vaults: an experimental and numerical study

The paper deals with a experimental and numerical study of a masonry barrel vault subjected to an incremental horizontal settlement of one abutment. The analyzed vault is very slender and with no backfill, as is typical of the vaulted roofs covering many Italian churches and other religious buildings of various dimensions, that often suffer a certain amount of settlement due to the deformation of the sustaining walls. In this paper, the experimental tests conducted at the University of Florence on a full-scale specimen has been assumed as a benchmark for numerical simulations carried out via different models, some implemented in the general purpose FEM software (Abaqus), and others specifically developed for masonry structures (Mady). The capability of the considered models to describe the actual behavior of the vault has been investigated, and their potential highlighted.

Stabilization of Gypsum Clay Soil by Adding Lime

Often, the temperature and water variation exist in semi-arid areas of a clayey soil leads to vertical and horizontal settlements, cracks in the soil and in general disorder to the building installed on this soil. The objective of this work is to stabilize the local gypsum clay soil, which poses problems at the level of self-construction built on it. Chemical soil stabilization can improve soil properties. In fact, adding natural lime to these clays can provide an ideal solution for stabilizing them through interesting modifications to their geotechnical properties throw the experimental tests on both unstabilized and stabilized soil samples by adding lime in quantities of 2, 4, and 6%, in percentages by the soil's weight, prepared at room temperature, The unconfined compressive strength (UCS) at different curing ages is measured, The results obtained provide a significant increase in compressive strength and modulus of Elasticity which allow better qualities and improve strength parameters throughout any phase of earthwork construction design that leads to strengthening subgrades, reducing the thickness, and, as a result, low construction costs. The results of the study show that (1) for the best utilization effect, the optimum percentage of lime is 6%; (2) the UCS is 3.23 times of the pure soil after curing of 28 days under the optimum percentage of lime; (3) the curing age has a significant effect on strength; (4) the main reason for the strength increase of the modified soil is that the crystal produced by the pozzolanic activity fills the pores of the soil. The ideal percentage is 6% lime treatment with a resistance of 2.3 MPa and 135.60 MPa the value of elasticity modulus at 28 days. Doi: 10.28991/CEJ-2022-08-11-010 Full Text: PDF

Surface settlement induced by horizontal directional drilling

Horizontal directional drilling (HDD) is a widely used trenchless method for underground utility connections. The associated ground settlement triggered by HDD depends on the size, types, and surface texture of pipe, diameter of borehole, and soil conditions. The present study investigates the surface settlement due to the construction of a 1067 mm diameter HDD, which will replace an existing sewer siphon under the SR-60 highway in Chino, California using empirical, and numerical methods. Based on the results obtained from the subsurface investigation, an empirical analysis was conducted first. followed by numerical modeling of the HDD using PLAXIS 2D software. A careful comparison between two different methods indicated closer values of surface settlement between the empirical method (7.3 mm) and the numerical modeling (4.6 mm). In addition, the shape of surface settlement and horizontal settlement curves for the empirical and numerical methods was found to be similar. The minor discrepancy between the two methods resulted as the numerical model can host several soil layers whereas the empirical equation can use only one type of soil. Finally, a parametric study was conducted to evaluate the effect of borehole cover depth, size, and soil parameters on surface settlement. It was observed that soil strength parameters yielded a greater effect on surface movement, whereas modulus of elasticity has a relatively smaller influence with zero contribution from Poisson's ratio.

Investigating Surface Deformation Caused by Excavation of Curved Shield in Upper Soft and Lower Hard Soil

Existing studies on surface deformation prediction consider single soil layers and straight-line excavation when investigating deformation caused by metro shield construction. In this study, we provide a new prediction method for studying the soil deformation caused by curved shield tunnel construction in the upper soft and lower hard soil. The deformation equations are derived using the Mindlin solution and random medium theory and are verified using engineering examples and numerical simulation. The influencing factors and laws of the surface deformation caused by the excavation are also identified. The study found that the horizontal settlement trough on the ground surface was distributed asymmetrically during the curve construction, with maximum settlement on the inner side of the curve. The offset and settlement values were affected by the thrust difference coefficients α and β and the turning radius. When constructing in the upper soft and lower hard soil layers, the settlement trough tends to become wider and shallower. The results show that the derived equation is suitable for actual engineering calculations, and the measured data are in good agreement.

Study on Environmental Effects Induced by Quasirectangle Shield Tunnelling with Analytical Stiffness Matrix

During the quasirectangle shield tunnelling, the soil around the tunnel is inevitably disturbed which results in different degrees of additional stresses and displacement of the soil. In this paper, the environmental effects caused by the construction of quasirectangle shield are analyzed by the analytical stiffness matrix method, focusing on the law of the additional stress field and the deformation of the multilayered soil induced by the construction of a quasirectangle shield. The results show that the additional stresses field has localized characteristics around the quasirectangle shield. The further away from the excavation face, the smaller the stress is. Also, shell friction and synchronous grouting pressure have a significantly greater influence on the additional stress field. Finally, the horizontal settlement groove of the quasirectangle shield is roughly symmetrical and parabolic along the tunnel axis, with a groove width range of about 20m. Synchronous grouting pressure has a greater effect on longitudinal ground deformation.

Static and Dynamic Analysis of the Shielded Tunnel in Alluvium Soil with 2D FEM Model

Transportation tunnels are strategic parts of all urban development projects. Challenges are faced while selecting the excavation techniques and support types in these underground constructions. Hence, sufficient information and knowledge are required while designing the shield support system in soft ground tunnelling. In this study, a two-dimensional plane strain finite element simulation of a tunnel having 350-mm thick reinforced concrete liner has been carried out. The effects of soil stratification, degree of saturation, and seismic loading have been considered for the analyses. Mohr-Coulomb’s constitutive model has been adopted to simulate the linear elastic-plastic behaviour of soil in static analysis. Furthermore, the dynamic response of horizontal shear waves (S-wave) has also been investigated on the tunnel’s model. It was observed numerically that the stresses and deformation reduced to 15% and 30% respectively when sandy silt (SM), soil layer moved towards liner in stratification analysis. The tangential and radial stresses increased by 24% and 35%, respectively, due to groundwater presence above the crown. Moreover, vertical and horizontal settlements have increased exponentially that led to a reduction in the shear strength of soil due to variation in water level. Also, ovaling (egging) deformation was observed in the liner due to the propagation of seismic shear waves at the base of the tunnel.

3D Numerical Simulation of the Influence of Drilling-blasting Subway Construction on Subgrade Settlement

Based on the tunnel between Junfeng road-Xiliuzhuang of Qingdao metro, the tunnel excavation model is established by FLAC3D software. The established calculation model mainly includes:(1) Free field boundary conditions are adopted around and at the bottom of the model;(2) The blasting load is simulated by triangle pulse wave;(3) According to the peak value V of the surface velocity, the peak value Pmax of the velocity in the triangular pulse wave is calculated by Sadovsky formula;(4) The calculation results show that the vertical settlement of subgrade is more significant when compared with horizontal settlement;(5) the calculation results are in good agreement with the field monitoring data. It shows that the method can simulate the dynamic characteristics of the model and reflect the dynamic response of subgrade settlement.

Proportional Restraints in Horizontal Patent Settlements

Competitors embroiled in a patent dispute always prefer to preserve and share monopoly profits, even if the patent is likely invalid. Antitrust has come to embrace a policy that requires horizontal settlements to be proportional in the sense that their anticompetitive effects are commensurate with the expected result of counterfactual patent litigation, which might have excluded the patentee's rival(s). But the standard presents serious practical complications, due to the uncertainty about counterfactual litigation, and as yet it has only been successfully applied to one type of settlement. We show that one can evaluate proportionality by focusing entirely on the nature of the firms' agreement, as this determines what the firms can agree on in relation to their expectations about litigation. We exploit this to propose a new enforcement approach that avoids the implementation problems with the current regime. This is a previous draft. The updated version is available at: https://papers.ssrn.com/abstract=3670815

Preliminary Report on the first season of fieldwork in Berettyóújfalu-Szilhalom

This study aims to present the first results of fieldwork conducted by the teams of the Römisch-Germanische Kommission (Frankfurt am Main) and the Institute of Archaeological Sciences of Eötvös Loránd University (Budapest) in the scope of a joint project. The investigated tell site, Berettyóújfalu-Szilhalom is well known by prehistoric archaeology due to earlier excavations. The main goals of the project were to gain a better understanding of Late Neolithic tell formation processes, to investigate the relations of a tell and its adjacent horizontal settlement and to get a more detailed picture on the Late Neolithic–Early Copper Age transition. Therefore we re-opened the refilled trench of the excavation carried out in 1976, collected bone, soil and micromorphological samples for further examinations, performed geomagnetic prospections, made drillings and field surveys.

Integrated Prospection Methods to Define Small‐site Settlement Structure: a Case Study from Neolithic Hungary

ABSTRACTDifferent human activities produce different material signatures, and therefore integrating several complementary prospection data sets provides a more comprehensive picture of site structure than any one method. We combine magnetic prospection data with soil chemistry and surface collection data from two small late Neolithic (ca. 5000 bc) settlements in eastern Hungary. Magnetic gradiometer survey helps to define basic subsurface features. Semi‐quantitative soil phosphate analysis improves our understanding of vertical and horizontal settlement boundaries and the locations of some activity zones. Through the surface distribution of burnt daub and pottery, controlled surface collection aids in our interpretations of structure and preservation at these settlements, as well as providing dating evidence. Spatial analysis, including the interpolation of chemical data, is performed in a geographical information system. Results indicate two different settlement types at contemporaneous sites, and suggest excellent preservation for site types that are poorly understood, relatively rare and generally poorly preserved in the archaeological record of eastern Hungary. In addition, this work provides the first comprehensive depiction of spatial organization at small late Neolithic settlements in the region. Copyright © 2013 John Wiley &amp; Sons, Ltd.

Experimental Study on Optimization Design of Variable Diameter Pile-Raft Foundation

Test model who’s scale is 1:10 was established. According to the actual engineering, through the model test, the laws about the settlement of the pile-raft foundation, vertical and horizontal settlement of soil, pile force, soil force and pile-soil stress ratio were studied under natural foundation, uniform and variable diameter pile-raft foundation. It can provide theoretical basis for Future research the pile raft foundation.

Régészeti kutatások egy késő neolitikus településen – Polgár-Bosnyákdomb (Előzetes jelentés)

Régészeti kutatások egy késő neolitikus településen – Polgár-Bosnyákdomb (Előzetes jelentés)

A Multiscalar Approach to Modeling the End of the Neolithic on the Great Hungarian Plain Using Calibrated Radiocarbon Dates

This article presents the results of a multiscalar analysis of 168 radiocarbon dates from Neolithic and Copper Age sites on the Great Hungarian Plain. We examined chronological patterns at different geographic scales to explore socioeconomic changes that occurred during the transition from the Neolithic to the Copper Age. The beginning and end of the Late Neolithic (5000–4500 cal BC) and Early Copper Age (4500–4000 cal BC) were modeled with14C dates calibrated with the CALIB 5.01 program and IntCal04 calibration curve. Our attempts to identify chronological subphases within these 500-yr-long periods were confounded by multiple intercepts in the calibration curve. The analysis indicated that terminal Late Neolithic (4700–4300 cal BC) and “transitional” Proto-Tiszapolgár occupations (4600–4250 cal BC) at tell sites were contemporary with initial Early Copper Age habitations (4450–4250 cal BC). Calibrated dates from small Early Copper Age settlements at Vészto-Bikeri and Körösladány-Bikeri document changes in community and household organization that took place over several decades during the transition to the Copper Age. Bayesian analysis indicated that the small fortified sites were occupied contiguously in phases of 30–50 yr. The younger Körösladány-Bikeri site was established before the older Vészto-Bikeri site was abandoned. When large nucleated Late Neolithic communities dispersed and established small Early Copper Age settlements, the pattern of vertical accretion that had created the Late Neolithic tells gave way to a pattern of horizontal settlement accretion at the smaller settlements.