Showing papers on "Settlement (structural) published in 2002"

Traffic-Load-Induced Permanent Deformation of Road on Soft Subsoil

Abstract: A method for predicting the traffic-load-induced settlement of road on soft subsoil with a low embankment is proposed. The traffic-load-induced dynamic stress in subsoil is calculated by the multilayer elastic theory (not covered in this paper). Then the plastic vertical strain in subsoil is calculated by an empirical equation, in which constants are related to the physical and mechanical properties of subsoil. The method was applied to analyze three different cases in Saga, Japan. Comparisons of the calculated values with field data indicate that the proposed method can provide a reasonable prediction of traffic-load-induced permanent settlement of the road on soft subsoil with a low embankment. The method is useful for designing the road with a low embankment on soft subsoil. For the cases studied with embankment thickness of 0.75 to 2.7 m, the depth significantly influenced by traffic load is about 6 m below the base of the embankments.

Effects of sedimentation on coral settlement and survivorship

Abstract: Settlement and survival of juveniles are key components of recruitment, which is in turn crucial to the persistence of coral populations. Settlement and juvenile survival of the coral Acropora millepora were measured in situ using experimentally elevated sedimentation rates. Sedimentation rates ranged between 0.76-1.32 mg.cm.d for reference sites and 1.88-11.70 mg.cm.d in sediment treatments. Settlement was significantly lower in the sediment treatments where it reached only 71% of levels in reference areas. The number of juvenile corals surviving at sediment treated sites after 8 months was 39% of levels at reference sites, however mortality did not vary significantly between treatments. These effects indicate that even relatively small increases in sediment accumulation would have negative impacts on coral recruitment. 1 University of Auckland Leigh Marine Laboratory, PO Box 349 Warkworth, New Zealand, r.babcock@auckland.ac.nz. 2 Australian Institute of Marine Science, PO BOX 264 Dampier Western Australia, 6713, Australia

Card settlement system, method, terminal device, information processing device and program, and recording medium storing card settlement program

Abstract: PROBLEM TO BE SOLVED: To provide an inexpensive card settlement terminal device using a cellular telephone. SOLUTION: This card settlement system 1 using the cellular telephone is composed of: a settlement information processing unit 11 installed in a settlement information center 10 for receiving and decrypting e-mails including the encrypted card settlement information, transmitting the same to a data processing unit 13 of a settlement agency 12 as the card settlement information, receiving the settlement result information from the data processing unit 13 of the settlement agency 12, and sending the settlement result information by means of an e-mail, a card reader for encrypting the card settlement information including a membership number, a settlement agency code and the other settlement information and transmitting the same as the encrypted card settlement information; and the cellular telephone 9 taking the encrypted card settlement information from the card reader 5 in a mail box, transmitting the encrypted card settlement information stored in the mail box to the settlement information processing unit 11 by means of the e-mail, and receiving the e-mail of the settlement result information from the settlement information processing unit 11. COPYRIGHT: (C)2004,JPO

Movements in the Piccadilly Line tunnels due to the Heathrow Express construction

Abstract: This paper presents the results of analyses of monitoring records taken from inside one of the existing Piccadilly Line tunnels during the construction of three station tunnels at the Heathrow Express Central Terminal Area. The monitoring data allow a detailed picture of the way in which existing segmental concrete-lined tunnels behave as a result of tunnelling works below. Settlement curves at critical construction stages are presented. It is shown that the computed ‘volume loss’ varied between 1·3% and 2·5%. Long-term settlement records indicate that the maximum settlement increased by 27% for a period three years after tunnel completion. This result is compared with earlier findings from the Heathrow trial tunnel. Asymmetry of the settlement troughs caused by the outer tunnels, constructed after the central concourse tunnel, is discussed, and asymmetry parameters are defined from a number of case histories. The relationship of asymmetry parameters to pillar width between tunnels is presented and discus...

Geogrid-reinforced railroad bed settlement due to cyclic load

Abstract: Results of large-scale laboratory model tests conducted to determine the permanent settlement due to cyclic load of the railroad bed for a proposed high-speed train route extending from Seoul to Pusan in South Korea are reported. The possibility of using geogrid layers as reinforcement to reduce settlement of the subbase layer was investigated. Based on the present model test results, it appears that practically all permanent settlement due to cyclic load is completed after application of 105 cycles of load. The most beneficial effect of reinforcement is derived when one layer of geotextile and one layer of geogrid are placed at the interface of the subgrade soil and subbase course.

Filling ability and plastic settlement of self-compacting concrete

Abstract: The use of self-compacting concrete (SCC) facilitates the placing of concrete by eliminating the need for compaction by vibration. Given the highly flowable nature of such concrete, care is required to ensure excellent filling ability and adequate stability. This is especially important in deep structural members and wall clements where concrete can block the flow, segregate and exhibit bleeding and settlement which can result in local defects that can reduce mechanical properties, durability and quality of surface finish.

Artificial Neural Network based Settlement Prediction Formula for Shallow Foundations on Granular Soils

Abstract: The problem of estimating the settlement of shallow foundations on granular soils is very complex and not yet entirely understood. The geotechnical literature has included many formulae that are based on several theoretical or experimental methods to obtain an accurate, or near-accurate, prediction of such settlement. However, these methods fail to achieve consistent success in relation to accurate settlement prediction. Recently, artificial neural networks (ANNs) have been used successfully for settlement prediction of shallow foundations on granular soils and have been found to outperform the most commonly-used traditional methods. This paper presents a new hand-calculation design formula for settlement prediction of shallow foundations on granular soils based on a more accurate settlement prediction from an artificial neural network model. The design formula presented is a quick tool from which settlement can be calculated easily without the need for computers.

Evaluation of Decomposition Effect on Long-Term Settlement Prediction for Fresh Municipal Solid Waste Landfills

Abstract: A considerable amount of settlement occurs due to the decomposition of municipal solid waste (MSW) in landfills over a period of years. Therefore, the effect of biological decomposition governs the long-term settlement characteristics of municipal solid waste landfills. In this study, we investigated the long-term settlement characteristics by applying a number of prediction methods to fresh MSW sites and predicting the settlement curves. Most proposed methods, excluding the power creep law, successfully predicted long-term settlement only if accelerated logarithmic compression due to decomposition of biodegradable MSW was included in the settlement prediction.

Effects of remedial measures for mitigating embankment settlement due to foundation liquefaction

Abstract: In Japan, after the Hyogoken-nambu earthquake remedial measures have often been constructed for river dikes supported on liquefiable sand beds. In this study a series of dynamic centrifuge tests wa...

Protrusion, Bioturbation, and Settlement Detection during Surface Survey: The Lowland Maya Case

Abstract: In upland settings in humid and semihumid temperate and tropical environments, bioturbation is a major factor in the burial of modest architectural remains, which are abundant components of the settlement systems of complex societies. Surface survey, favored by archaeologists of complex societies as a settlement detection method, seldom is appropriate for discovering architectural remains buried through bioturbation. Where the focus of analysis includes settlement represented by architectural remains, surface survey is appropriate only where all or a representative sample of all types of architectural remains are protrusive. “Protrusion” describes a relationship (affected by climate, environment, topography, and cultural variables) between the height of a ruined building and the depth of the biomantle, which is the zone of bioturbation. To enable archaeologists to assess the appropriateness of settlement detection procedures, including surface survey, I propose a scheme that classifies architectural remains in terms of their protrusion, building height, and visibility characteristics. The scheme can be employed to determine if and why architectural remains are protrusive in particular study areas. To demonstrate its analytical utility, I apply the scheme and the model of building burial through bioturbation that underlies it to the problem of Maya “invisible” settlement. I conclude that in the Maya lowlands of Mesoamerica, building remains buried through bioturbation are a more abundant settlement category than many archaeologists have supposed.

Temporal and spatial variation in settlement of the gastropod Concholepas concholepas in natural and artificial substrata

Abstract: Settlement of Concholepas concholepas (Gastropoda: Muricidae) on natural and artificial substrata was studied between April 1999 and March 2001 at two sites in central Chile; the Las Cruces Marine Reserve and El Quisco Management and Exploited Area. Four different artificial materials were tested in the low intertidal zone during 1999 settlement season to determine their properties as settlement and microhabitat substrata for competent Concholepas larvae. Globular pads made of plastic filaments were identified as the best artificial collectors, exhibiting overall higher settlement rates than rock plots and lower variability among replicates within a given site. Thus, subsequent monitoring of settlement used only these globular pads that were replaced twice monthly. The temporal pattern of settlement was remarkably similar from year to year, starting at the end of austral winter (August-September) and ending in summer (December-January), defining a temporally restricted settlement season. Settlement at two sites within the Marine Reserve of Las Cruces was significantly higher than at sites in El Quisco. However, during the second settlement season, an additional site at El Quisco exhibited settlement rates comparable to those observed at Las Cruces. The results show that Concholepas settlement varies significantly over scales of several hundreds of metres as well as tens of kilometres, probably due to differences in coastal oceanographic conditions.

Ground Subsidence due to a Shallow Tunnel in Dense Sandy Gravel

Abstract: Finite-element procedures have been applied to predict ground subsidence caused by tunneling; however, the calculated results are strongly dependent on the adequacy of the model used. The construction of a shallow tunnel in the typical gravel of Santiago (Chile) is herein back-analyzed using a finite-element method based on a modified version of the hyperbolic model. Observed ground subsidence as a function of distance to the face and to the tunnel axis is examined and related to the construction procedure. Although the ratio of overburden cover to excavation width was 0.52, the maximum settlement measured was only 9 mm. It was found that, as a result of the excavation process, a certain thickness of soil behind the excavation line experienced a significant alteration. The hyperbolic parameters of the disturbed soils were determined by fitting the calculated subsidence to the observed results. From the good agreement obtained, it is concluded that the model used represents reasonably well the construction stages of the tunnel and the stress-strain behavior of the materials involved.

Larval settlement of corals in flowing water using a racetrack flume

Abstract: Although the larvae of marine invertebrates settle in currents, few studies have examined settlement under flow. We studied the settlement of two brooding coral larvae with different behavior in a flow using a small racetrack flume made of polycarbonate and acrylic (58 cm long). Flow was generated using a digitally controlled gear-motor-driven paddle wheel. The settlement rates of the larvae, Heliopora coerulea and Pocillopora damicornis, were observed at three flow speeds: 1.6, 4.4, and 9.8 cm/sec, which correspond to the currents at low, mean, and ebb or flood tides, respectively, at Shiraho Reef flat, Ishigaki Island, Japan. The settlement rate of H. coerulea larvae decreased with increasing flow speed (20% at 1.6 cm/sec, 2% at 9.8 cm/sec). In contrast, the settlement rate of P. damicornis larvae was high at all flow speeds (> 50% at all flow speeds). This difference in the larval settlement rates of the two species is in accordance with the current conditions in which the adult corals are distributed.

Electronic settlement system and electronic settlement method

Abstract: PROBLEM TO BE SOLVED: To provide an electronic settlement method capable of functioning without being influenced by a use limit or a deposit balance, and applying a use result to processing by a user SOLUTION: This electronic settlement method receives a deposit from a user 4 in an electronic settlement account every installment period dividing a specified period, and the difference generated due to electronic settlement processing is cleared up at the expiration of the specified period To a use result of the electronic settlement, classification codes such as a use place classification, a use item classification, and a user classification are added in advance The use result of the electronic settlement is classified and totaled up by using the added classification codes to output, thereby obtaining an electronic settlement use statement recording medium 5 capable of being applied to processing required by the user 4

Investigation of settlement at bridge approach slab expansion joint: numerical simulations and model tests

Abstract: Researchers propose a new approach slab, which has a one-span slab, after reviewing the existing knowledge and the existing practice, performing numerical analyses, and conducting model scale simulations. Some of the most important conclusions from the numerical analyses are: (1) The presence of the abutment wall founded on piles creates a difference in settlement between the abutment wall and the embankment; (2) This differential settlement is drastically reduced in the absence of the wall; (3) The transition zone is about 40 ft with 80% of the maximum settlement occurring in the first 20 ft for a uniform load case; and (4) The size of the sleeper slab and support slab influences the settlement of the slab when load is applied to the slab, the optimum width of both slabs is about 5 ft, and the height of the embankment is influencing the settlement of the embankment. Based on the work done in this research project, the new recommended approach slab is at least 20 ft long and has one span from the abutment to the sleeper slab. It should be designed to carry the full traffic load without support on the soil except at both ends; the support slab used in the current solution is removed and the wide flange is kept on the embankment side as a temperature elongation joint. This new approach slab will simplify construction, be less expensive, and place less emphasis on the need for very good compaction close to the abutment wall. The BEST (Bridge to Embankment Simulator of Transition) device, which is a 1/20th scale model of the typical transition, was used to simulate the existing approach slab and the new proposed approach slabs. The results indicate the following: (1) The proposed new approach slab (one-span) with a 20 ft simulated span length gave a smaller bump than the current two-slab approach slab; (2) The soil with the higher compaction level developed less bump at the sleeper slab than the lower compaction soil; and (3) The bump size increased with the number of cycles in a straight line on a log-log plot. The maximum vertical acceleration of the simulated car was 32 m/sq sec at a velocity of 13.78 km/hr.

Invertebrate re-colonisation i Mariager Fjord (Denmark) after a severe hypoxia: I. Zooplankton and settlement

Abstract: Abstract A severe hypoxic event was observed in the innermost 20 km of the Danish estuary Manager Fjord during August 1997 where the entire water column was totally anoxic for two weeks causing extinction of almost all metazoa. A sampling programme was initiated the following spring and summer at three stations in the anoxic part of the estuary. We describe the re-colonisation by zooplankton and in particular meroplankton, and the subsequent potential settlement by bivalves, gastropods, polychaetes and cirripeds. Due to extinction of the benthic community the zooplankton organisms were considered recruited entirely from outside the study area. Two water intrusions from the open water Kattegat were identified based on calculations of mass balance of salt and on phytoplankton composition. Rotifers were the first zooplankters to appear followed by cladocerans and copepods. The meroplanktonic bivalve larvae were followed by polychaete larvae, gastropod larvae and last cirriped nauplii, all with a maximum density of <100 larvae l-1. Mortality of meroplankton comprised 59–99.5% during the study period when the population is considered to develop in a closed system. However, a simple model including estimated in- and outflow of water and hence larvae forecast 13–69% mortality depending on simulation time and instantaneous mortality rate. In the absence of predators, the disappearance of larvae is suggested to be due to functional food limitation and settlement. Potential settlement was observed at all three stations after 3 weeks of sampling. The succession observed among settlers was: bivalves and polychaetes — gastropods — crustaceans (cirripeds). This is comparable to the succession of taxa in the plankton. The potential settlement rate of polychaetes increased from the outermost station towards the innermost station and a tendency to initiate settlement earlier at the innermost station was observed. The polychaete settlement rate comprised up to 30–40 × 103 ind. nr-2 d-1 and was evident mainly in relation to the first water intrusion. A similar pattern, although with a lower settlement rate, was found for bivalves. The settlement rates of the other taxonomic groups revealed no systematic pattern and were in the range of >5 × 103-10 × 103 individuals m-2 d-1. Due to hypoxia the inner section of Manager Fjord is susceptible to defaunation regularly, but the benthic diversity is remedied after a surprisingly short time by re-colonisation from adjacent sections of the estuary.

A simplified nonlinear settlement prediction model for foundations on sand

Abstract: This paper presents a simple method for predicting the settlement of spread foundations on sand operating under typical working loads. The method accounts for the well known effects on soil stiffness of strain, stress level, and density dependence, but adopts the simplifying assumption that the stress distribution beneath a loaded foundation can be obtained from Boussinesq's equations for an elastic half space. Despite this simplification, the method is shown to predict foundation responses that closely match those computed using more sophisticated finite element (FE) analyses and those measured in laboratory footing tests, where the stiffness characteristics in triaxial compression were well defined. The method is also seen to predict general variations of foundation settlement with bearing pressure, foundation width, and degree of preloading that are entirely consistent with empirically observed trends. It is concluded that satisfactory settlement predictions for shallow foundations on cohesionless soil may be obtained using Boussinesq's equations if the soil's vertical stiffness characteristics, as inferred from triaxial compression data, can be specified with some degree of precision.

Approaches to numerical modelling of ground movements due to shallow tunnelling

Abstract: Numerical prediction of ground movements due to tunnelling depends on the methods, constitutive models and parameters applied. Firstly, two basic assumptions widely used in current computational practice to predict surface settlement due to tunnelling are analysed in the paper. These are the elastic-perfectly-plastic material model and the load reduction or lambda-method approximating the 3D effect of tunnel face advance through 2D FEM solutions. Results of three parametric studies are presented. Applying different material models and parameters, the results of the lambda-method are compared with monitoring results in the first study and with 3D FEM results in the second one. In the third study the effect of in situ stress state (K sub 0 = 0.5; 1.0; 1.5) on the shape of surface settlement trough is analysed using 3D FEM and lambda-method with different constitutive models and parameters. A strong influence of K sub 0 on the amount of stress release due to tunnelling and hence on the depth and width of settlement trough was found.