Actual Settlement Research Articles

파쇄대가 과대분포한 암반지역에서 터널의 거동특성에 관한 연구

본 논문은 설계단계에서 지반조사와 수치해석을 통해 예측된 터널의 거동특성과 실제 시공단계에서 어떠한 변형특성을 보이고 있는지 RMR 및 계측데이터의 비교분석을 통해 선정된 터널지보시스템의 선택적 적용을 보여준다. 이는 파쇄대가 과대분포한 암반지역에 터널을 설치할 경우, 터널굴착지반의 거동은 지반의 특성과 보강공법 등의 영향에 따라 상이한 거동특성 때문이다. 그러므로, 본 연구에서는 지반설계자가 단층대 및 파쇄대가 과대 분포한 암반지역의 터널 설계시, RMR-계측 데이터 분석과 지반물성치 저감에 따른 매개변수 분석을 비교하여, 지반 설계자가 향후 유사한 파쇄대가 과대분포한 지역의 터널거동특성을 예측할 수 있도록 하고자 한다. This article is to apply the tunnel support system selected after comparatively analyzing of RMR and tunnel instrumentation between the tunnel behavior characteristic predicted through geotechnical investigations and the numerical analysis at the design stage and the properties deformation occurred at the construction stage. This attempt results from the behavior characteristic of the tunnel excavation ground shown differently in accordance with the ground quality and reinforcement method. This, therefore, provide the data and results analysed the actual decision RMR-crown settlement & convergence and reduction of material property of ground as parameters. Also, it's shown that the tunnel designer is able to predict tunnel behavior characteristic when designing in bedrock areas excessively distributed faults and fractured zones.

Differential settlement effect on reliability of bridge superstructure and implementation in Load and Resistance Factor Design specification

Maximum deterministic differential settlement is used in current American Association of State Highway and Transportation Officials Load and Resistance Factor Design specification. However, the deterministic differential foundation settlement is quite different from the actual settlement due to the soil’s large variability. This article investigates the effects of the random differential foundation settlement on the reliability of bridge superstructure. A lognormal distribution with a coefficient of variation of 0.25 of random settlement is used in reliability analysis. Dead and live loads are modeled as random variables with normal and Gumbel Type I distributions, respectively. Then, the reliability of bridge superstructure considering random differential settlement effect is calculated using the first-order reliability method. Considering the regional traffic condition on Missouri roadways, the effect of a live load reduction factor on bridge reliability is investigated. The reliability indices of 14 existed bridges and 31 new designed multi-span girder bridges are calculated. It is demonstrated that small change in differential settlement can significantly reduce the reliability of the superstructure, depending upon the span length and rigidity of the girder. For the 31 new designed bridges without the settlement consideration in design can tolerate an extreme settlement of L/500 without reduced live loads and L/2500 with reduced live loads in the case of a bridge reliability index of 3.5. The reliability analysis results also indicate that without reduced live loads, current American Association of State Highway and Transportation Officials specification with a load factor of 1.0 for the differential settlement has enough safe margins within an allowable settlement of L/250. However, when live loads are reduced, the load factor for settlement has to be amplified. The calibrated load factor curve of differential settlement within allowable settlement L/250 is provided to achieve the target reliability index of 3.5.

Design of pile configuration for optimum raft performance

Design of raft foundations on medium to dense sand is usually dictated by the allowable settlement rather than by a requirement to achieve an adequate margin against bearing failure. Piles are often installed under rafts to improve settlement performance, primarily the differential settlement, thereby to enhance structural performance. A practical design method has been developed for piled-raft foundations as a part of the Kinaxixi multi-use complex project in Angola; this is aimed at achieving an optimum pile configuration and is described in this paper. This method involves an iterative procedure to achieve consistency, with the design models representing the geotechnical and structural behaviours. The actual settlement of the raft is compared with the predictions as a means of validating the design method.

Settlement Prediction of Road Soft Foundation Using a Support Vector Machine (SVM) Based on Measured Data

The suppor 1 t vector machine (SVM) is a relatively new artificial intelligence technique which is increasingly being applied to geotechnical problems and is yielding encouraging results. SVM is a new machine learning method based on the statistical learning theory. A case study based on road foundation engineering project shows that the forecast results are in good agreement with the measured data. The SVM model is also compared with BP artificial neural network model and traditional hyperbola method. The prediction results indicate that the SVM model has a better prediction ability than BP neural network model and hyperbola method. Therefore, settlement prediction based on SVM model can reflect actual settlement process more correctly. The results indicate that it is effective and feasible to use this method and the nonlinear mapping relation between foundation settlement and its influence factor can be expressed well. It will provide a new method to predict foundation settlement.

The Pre-Evaluation of Stability during Tunnel Excavation using Unconfined Compression Strength of Intact Rock or Rock Mass and Crown Settlement Data

PURPOSES : It is difficult to estimate tunnel stability because of lack of timely information during tunnel excavation. Tunnel deformability refers to the capacity of rock to strain under applied loads or unloads during tunnel excavation. This study was conducted to analyze a methods of pre-evaluation of stability during tunnel construction using the critical strain concept, which is applied to the results of tunnel settlement data and unconfined compression strength of intact rock or rock mass at the tunnel construction site. METHODS : Based on the critical strain concept, the pre-evaluation of stability of a tunnel was performed in the Daegu region, at a tunnel through andesite and granite rock. The critical strain concept is a method of predicting tunnel behavior from tunnel crown settlement data using the critical strain chart that is obtained from the relationship between strain and the unconfined compression strength of intact rock in a laboratory. RESULTS : In a pre-evaluation of stability of a tunnel, only actually measured crown settlement data is plotted on the lower position of the critical strain chart, to be compared with the total displacement of crown settlement, including precedent settlement and displacement data from before the settlement measurement. However, both cases show almost the same tunnel behavior. In an evaluation using rock mass instead of intact rock, the data for the rock mass strength is plotted on the lower portion of the critical strain chart, as a way to compare to the data for intact rock strength. CONCLUSIONS : From the results of the pre-evaluation of stability of the tunnel using the critical strain chart, we reaffirmed that it is possible to promptly evaluate the stability of a tunnel under construction. Moreover, this research shows that a safety evaluation using the actual instrumented crown settlement data with the unconfined compression strength of intact rock, rather than with the unconfined compression strength of a rock mass in the tunnel working face, is more conservative.

PERFORMANCE PREDICTION OF PREFABRICATED VERTICAL DRAIN IN SOFT SOIL USING FINITE ELEMENT METHOD

Prefabricated vertical drain (PVD) had successfully been applied in many soft ground construction projects. Finite element method (FEM) could assist designers to model very complex subsoil and structural elements. In this study, finite element analysis (FEA) is performed to verify the effectiveness of modelling of PVD in subsoil using computer software, Plaxis V8. The field settlement data were collected at two particular locations and were analysed using Asaoka’s method to estimate the ultimate settlement and back-calculated the coefficient of horizontal consolidation for these two particular location. Thereafter, by using back-calculated coefficient of horizontal consolidation, FEA were performed to predict the time rate settlement and compared against field settlement results. From the time rate settlement curves generated by FEM, the ultimate settlements were predicted using Asaoka’s method. The ultimate settlement predicted from FEM is slightly lower compared to actual field settlement monitoring result, but the degree of consolidation settlement achieved were higher.

Transportation Modeling as a Didactic Tool

Background. Interconnections of settlement, transportation, and society are extremely varied, complex, and context-specific. The Simulation Game HUMAN SETTLEMENT AND TRANSPORT (HST) aims to assist in the training and continuing education of transportation students and professionals with the transportation modeling software VISUM. Aim. The key research questions are as follows: Can transportation models be used as didactic tools to improve the teaching on causal chains between land use and transport? Why and how does transport modeling enhance students learning in transportation planning and settlement structure? What are the self-reported learning outcomes and how do they vary from conventional didactic settings such as chalk-and-talk teaching, case studies, closed exercises, and desk research? Method. A case study is used to evaluate the game’s ability to simulate the complexity of actual human settlement and transportation. We focus on self-reported learning and how the expert game encourages students to discover knowledge. Results. This expert game successfully replicated complex and context-specific scenarios that actual urban planning committees might face. Participants revealed that they unearthed interrelations between settlement, transportation, and society similar to those found in the relevant academic literature. Conclusions. The results affirm the game’s effectiveness as an educational tool for transportation engineering, urban planning, and transportation modeling students and professionals. Recommendation. This research suggests that properly incorporating policy games into the curriculum can enhance students’ learning in transportation planning and settlement structure.

Livelihood Transitions and Changes of Sea Nomads or Urak Lawoi Fisher-folk in response to Tourism on Lipe Island, Andaman Sea, Southern Thailand

The Urak Lawoi fishing community on Lipe Island, Andaman Sea in Southern Thailand have faced challenges in the transition of livelihood patterns as well as from other changes due to rapid development of tourism sector on the island. This study aimed to investigate the transitions at the island and the changes to the Urak Lawoi community by employing a qualitative approach. Data collection was designed to analyze level and patterns of livelihood transitions and changes to the Urak Lawoi using field observation, interviews, and structured questionnaires. A total of 128 Urak Lawoi households were approached and engaged in formal interviews. Data obtained were analysed using descriptive statistics. Historical evidence revealed that the Urak Lawoi were the first inhabitants of the Lipe Island located just on the Thai side of the national border between Thailand and Malaysia. Looking back, there are four main periods affecting the lives and livelihood of the Urak Lawoi on the island; 1) first actual settlement of the Urak Lawoi on the island (at around 1897); 2) changes in social structure and decentralization that emerged in the period after the second World War; 3) intensive tourism on the island that followed major tourist promotions in the early 2000’s; and 4) present stage with increased competition over resources and space. Tourism development affected in many ways on livelihood of the Urak Lawoi. Some impacts are more visible while other impacts are more difficult to distinguish. Among the obvious negative impacts there were an increase in sewage accumulation, poor relationship with park officials, and drug addiction among youths. Impacts defined as positive included improved convenience of travel to the mainland, increases in income and (material) benefits, and more occupation opportunities in tourism-related enterprises.

Emerging socio-spatial pattern of Chinese cities: The case of Beijing in 2006

China's market reforms are restructuring its cities. The value of land, previously allocated by the state – is now better reflected in market price, with a strong gradient from high values in the center to lower values in the periphery. Using data from a 2006 Beijing household survey, this paper explores the extent to which the emerging socio-spatial pattern conforms to this new pattern of land value gradient. The results offer little support for this. We argue that although land prices are becoming a significant determinant of urban development, the actual settlement pattern is still strongly affected by other factors. One is the inertia of the socialist pattern placing households with higher standing in that system near the center. Another is the continuation of a set of policy rules that relegated migrants to peripheral locations. Land values do matter but market processes based on price still operate within a larger pattern determined by settlement history and public policy.

Monitoring of Inland Tide Embankment of Binzhou Port

For the purpose of foundation and structure stability during the construction of tide embankment, three monitoring projects including embankment settlement monitoring, berm platform settlement monitoring and pore water pressure monitoring are installed. Integrated monitoring data shows that foundation appears oversize instantaneous settlement on account of high construction speed, short loading interval at initial stage. Following with the shaping of embankment, stable monitoring data range, slow change rate and high dissipation speed of pore water pressure come along. Based on actual embankment settlement data, consolidation degree of soil mass is high and foundation stability becomes strong by means of hyperbolic curve.

Design and analysis of a large horizontal vessel supported on multiple saddles according to three-moment theorem and Zick’s method

For the engineering design of large horizontal vessels with uneven multiple saddles, no clear specifications are given in design codes, especially with uneven settlements. In this paper, an analytical method based on three-moment theorem with settlements is introduced to evaluate the shear forces and bending moments at some critical cross-sections of a large horizontal pressure vessel supported on 10 saddles with uneven settlements. Zick’s stress analysis method for a horizontal vessel supported on two saddles is extended to the multiple saddle arrangements. It is found that as a result of varied cross-section and uneven saddle supports, the shear forces and bending moments are different at different saddle sections. Finite element calculations are also performed to prove the analytical solutions. Results show that for the vessel without settlements, the bending moments and reactions obtained by the three-moment equation method are slightly larger than those obtained by finite element method. Non-uniform deformation of the vessel at different saddles may be contributed to the differences of the two results. For the vessel with settlements, the bending moments and reactions at some saddles obtained by the three-moment equation method are quite larger than those obtained by finite element method. But if the actual axis settlement of the vessel is applied to the three-moment equation method, the two results are close to each other. Experiments are also carried out to verify the reliability of the proposed method.

Refined Model of the Concrete Dam at the Boguchanskaya HPP Based on Field Obervations

An example is cited for use of actual settlement observations of the rock bed of the dam under construction at the Boguchanskaya HPP for more precise definition of its deformation model.

Predictions of settlement in peat soils

Predictions from laboratory tests of the compression behaviour of peat from 14 sites are compared with full-scale field loading at five sites. Data presented confirm the heterogeneous nature of the deposits. However, for typical engineering works, calculations based on laboratory test data are likely to give reasonable predictions of the magnitude of immediate and primary compression. Standard (20 mm thickness) samples may give misleading data on time for primary consolidation. Thicker samples (e.g. 50 mm) should be used. Sampling by conventional samplers, as used for mineral soils, can cause densification of the peat, resulting in underestimation of actual settlement. Block samples or sample tubes with serrated cutting edges are recommended for peat soils. It was found that the data presented follow the C α / C c law of compressibility. There is also is some evidence to suggest that the H 2 scaling law may be applicable. Good correlations were found between vertical yield stress ( p vy ′) and compression index ( C c ) and index parameters such as water content ( w i ). Conventional staged construction with surcharge loading may be successfully applied to peat soils as long as adequate drainage exists to permit consolidation over reasonable time intervals.

Prediction on Ground Surface Settlement Caused by Subway Shield Construction in Xi'an

In order to study the ground surface settlement induced by shield tunneling, on the background of Xi'an metro line 2, this paper made use of the measured ground surface settlement to conduct characteristic parameters fitting of the settlement trough by Peck formula and the modified stiffness approach, proposed the initial suggestive value of the relevant calculation parameters, predicted the ground surface settlement by the formula with the determined parameters and compared the settlement with the actual settlement observation. The results show that the determination of the parameters is basicly right, the revised formula can be used to forecast ground surface settlement of Xi'an subway construction and finally a modified prediction formula is given.

Performance of soil instrumentation on settlement prediction

Settlement analysis is very important and should be calculated before construction begins. In this study, there were two methods used to determine the prediction of total settlement. The actual value of total settlement was obtained from the instrumentation, which consists of the settlement plate and the magnetic extensometer. The prediction of total settlement was calculated by using the Asaoka (1978) method and compared to actual settlement from the settlement plate. Another method to predict the total settlement is the Terzaghi method in theory of one-dimensional consolidation and comparing those data with the actual settlement obtained from the magnetic extensometer. The comparison shows that both settlement predictions tend to give higher values of settlement than those obtained from the instrumentation.

Discussion of “Load tests on full-scale bored pile groups”

Discussion of “Load tests on full-scale bored pile groups”

Wavelet Estimation Method for Short-Term Prediction of Deep Pit Settlement

A wavelet estimation method is presented herein to estimate deep pit settlement. In this method, the pit settlement is decomposed into the trend settlement and the stochastic settlement by using Wavelet Analysis based on the characteristic of influencing factor. The model identifier is established by using artificial neural network (ANN), and trained to approximate the trend settlement. Then, the prediction controller developed could be applied for estimating the actual settlement. Finally, the verification examples show that the WIAN is an effective tool for predicting the pit settlement dynamically , high precision could be expected and achieved.

Tall Building Subsidence Data Regression Analysis Methods and the Final Settlement Value Prediction

In order to provide reference data for the safe construction and validation of the design method is correct, the subsidence monitoring for tall buildings (high-rise structures) which are being in the construction or completed. In this paper according to the actual settlement monitoring data, on basis of considering the construction stage, the settlement data were segmented regression analysis. The results show that in stage of load (in construction) uniform increasing, the settlement and load a linear regression analysis results are better than the results of settlement with time linear regression analysis, While in the building after the completion, the settlement with time were the logarithm function regression analysis, hyperbolic regression analysis and power function regression analysis. The regression analysis results show that hyperbola regression analysis method is of minimum variance and the regression analysis effect is best, the final settlement value was predicted and providing reference basis for construction and design.

Lystrup Østergård – En værkstedsplads fra yngre stenalder

Lystrup Østergård – En værkstedsplads fra yngre stenalder

Predication and Analysis on Ground Settlement Induced by Shielding Tunneling Construction

This paper takes Shenyang metro engineering with sandy soil for background, and the ground settlement induced by shielding tunneling construction is predicated and analyzed. Make clear the influential areas of lateral settlement in accordance with the monitoring data. Use traditional Peck Formula to fit actual settlement curve of the cross-section. From the curve fitted by Lagrange interpolation function, the half width i of the settlement tank can be gained. And then calculate the volume of the settlement tank, the improvement factor k and volume loss rate VL. The Peck Formula with improved factors can suitably predict the ground surface settlement.