The commonly used design specifications of caisson foundation were reviewed in this paper. The model that simulates lateral resistance of a caisson foundation contributed from various soil springs connected to the caisson was investigated analytically and numerically. Results showed that the resistance comes majorly from the horizontal subgrade reactions in front/back of the caisson. Based on that, modeling for the lateral response of a caisson can be approximately simplified to only considering the horizontal soil reactions sarrounding the caisson, which makes the mechanis analysis much easier. This simplified model can then be utilized to directly implement the analytical solutions of the lateral response of a rigid caisson embedded in the elastic soils and in the perfectly elasto-plastic soils, which are useful for preliminary analysis in engineering parctice.
In this case, the cable connection station locates at Taipei metropolis, which located on a slope land and of protected forest areas. For the machine tools transportation and the mud hole as waste soil dump, the Raise Boring Method with temporary cableway is applied to reduce the environment impact. This paper introduces the design and construction of foundation for cable connection station, including the Raise Boring Method, cableway installation, shaft reaming, the excavation expansion construction of fan room and the structure construction task.
In this article, the geological properties of Jhongli Terrace are reviewed and rule of selecting foundation type for bridges herein is proposed. Because of the limitation of construction area and high loading requirement of bridges, well foundation is recommended. Design and construction procedures of well foundation are also reviewed. Due to the high permeability of gravel layer and loose deposit of weak rock, scouring and gushing water occurred during excavation, engineer adopt measures such as grouting, cut-off pile, and drainage system to accomplish the construction of well foundation. The purpose for the article is to provide a helpful reference on similar ground condition.
Kao-132 line in Maolin, Kaohsiung city was constructed along the upstream of Jhoukou River. The landscape is eminent because of its meandering form and has been a well-known tourist resort. In 2009, the typhoon Morakot severely damaged the road. After detailed forensic investigation and reconnaissance study, the future disaster-induced damage can be minimized by using various design methods. From the geotechnical point of view, the rebuilt can be categorized with different causes of failure, including trench erosion, dip slope and slate creep. For roads that are restricted by available funding and construction feasibility, simple repair is recommended.
Since the disasters usually happen repeatedly in the same areas, monitoring devices were installed in sections of road in order to study the rainfall and seismic effects to the road after construction. When sever rainstorm warning is issued from the Central Weather Bureau, the monitoring data can provide agencies reference information for traffic control. The rebuilt has been completed for more than 3 years and the road has been maintained in good condition. The sever rainstorm on June 12, 2013 did not cause much damage except a few large displacement. From this case study, the concept of simple repair with monitoring system is a viable option for new construction and rebuilt of mountain roads.
To meet the tight schedule of construction, a caisson method that uses anchors to provide reaction forces can be introduced for the launching shaft in shield tunneling. The method does not require an interior bracing system to provide excavation stability that always becomes obstruction during assemblage and trial operation of shield machine. Compared to traditional one that uses dead weights to descend each caisson section, the method can reach higher criteria for verticality. The induced surface settlement can be significantly reduced, resulting in less effect on adjacent structures or facilities. This paper describes a case history in Kaohsiung City where a launching shaft with 18 m in diameter and 40 m in depth is constructed using the caisson method. Key consideration in planning, design, and construction management is illustrated. According to monitoring results, the method is proved to be time and cost effective for a tight-schedule project.
The units of diaphragm wall, also called as walled-type piles or rectangular piles, were designed as foundations to support the vertical loadings of superstructures common recently in Taiwan. However, the cross-sections and construction methods of walled-type piles were rather different from those of conventional larger-diameter circular bored piles and the available test results of walled-type piles loaded to ultimate failure were still few, thus the bearing behaviors of walled-type piles should be investigated. Results of six compressive load tests of walled-type piles, which fully instrumented and installed in New Taipei City, are studied in this paper. First the characteristics of t-z curves of various alluvial soils and q-w curves of gravel layer are evaluated, and the differences of load-deflection (Q~S) curves and q-w curves for piles with or without base grouting are discussed. Then the representative nonlinear t-z curves and q-w curves for various soil strata are summarized; in addition, the simplified linear models for representative t-z curves and q-w curves together with the corresponding parameters of stiffness and strength are proposed. Accordingly the load-deflection curves, which designated as the “performance curves”, for walled-type piles with various cross-section and lengths are simulated. Besides, the bilinear models for load-deflection curves as well as the corresponding equivalent stiffness are suggested for the analysis of soil-structure interaction of pile-raft foundation. Results of this case study indicates that the simulation method employing the t-z and q-w curves can be used to estimate the bearing behavior of walled-type piles very well; the simplified linear models and analysis methods proposed are suggested to be utilized in interpreting the results of pile load tests conducted in the other sites, thus the applicable analysis models can be established.
A construction case located in Taipei which is adjacent to main road and important structures is introduced in this paper. In order to increase construction safety and reduce the risk in the deep excavation projects, cross walls, buttresses and ground treatment are used aside from retaining diaphragm wall. The cross walls are also served as the foundation for the building while completing excavation. Two commercial software including RIDO and Plaxis are used to analyze the deformation behavior of retaining wall as well as adjacent ground. Besides, ETABES is used to simulate the interaction of structure and cross walls.
The excavation has reached the designed depth so far. Based on the monitoring results, the deformation of retaining wall is quite consistent with analyzing results which shows the assumptions and parameters used in the analysis are reasonable. Also, cross walls, buttresses and ground treatment are helpful to control the deformation. Due to the good agreement, the follow-up construction of building and persistent monitoring are expected.
For the needs of domestic economic development, the public transportation construction have been not enough gradually. However, the available land for the construction is reducing, and the demand of the environment protection is increasing. So that these projects must consider a variety of environmental factors, and select the appropriate foundation type to various environmental constraints. In the past, the foundation type is usually selected the spread footing type and pile foundation. But for the space-constrained and steeper slopes areas, the large construction equipment is hard to work. In such case, the well foundation is the another better choice. However, there are also some limited and considerations of the design and construction of well foundation. This article presents the case studies on design and construction of well foundation for the reference of the future construction works.
Taiwan Taoyuan International Airport Access MRT System A1 Station & C1/D1 Relevant Development Building Pile Foundation Preliminary Loading Test Content and Application
本次前期載重試驗主樁尺寸為1.3m x 2.7m x 52m，利用電子式荷重計、電子位移計、鋼筋應力計、樁體變位計、自動化測讀設備等儀器，於每階段加載時所規定之時間擷取試驗數據資料，配合各儀器所埋設位置，計算每一節樁身分段之軸力傳遞與摩擦力分佈狀況，以及每一地層之摩擦應力發揮與變位關係之t-z曲線、承載層反力發揮與變位關係之q-z曲線等成果，提供作為進行不同尺寸壁樁承載力與載重－沉陷量關係之回饋分析計算之用。
Taiwan Taoyuan international airport access MRT system A1 station and relevant development building is located on Parcel C1, D1. In order to provide the design parameter of high building’s deep foundation, performing preliminary loading test in diaphragm wall and pile engineering contract.
The scale of test pile is 1.3mx2.7mx52m, the automatic electric instruments including load cell, LVDT, installed in testing pile reinforcing bar stress transducer, telltale etc. had been measured by computer and data logger at indicated time for every step of loading. The load transfer and friction development of pile and stratum t-z & q-z curve may be calculated using the data from every instrument. The result of loading test could be applied in feedback analysis for different scale of pile bearing capacity and settlement analysis for C1/D1 relevant development building pile foundation.
A new viaduct was constructed to relieve the congesting traffic flow on National Expressway No. 1,from Wugu to Yangmei. Three difference excavation methods were used to install the bridge pier foundation along the slope of embankment for National Expressway, such as braced cut with soldier beam retaining wall, open rectangular excavation with shotcrete wall and soil nail retaining system, and vertical round shaft excavation with shotcrete wall and horizontal beams.
Monitoring results of inclinometers located near the bridge pier foundations during foundation excavation were used to investigate the soil movement of upslope after each stage of excavation. In addition, the possibility of potential sliding failure was also analyzed due to the appearance of several parallel tensile cracks on the expressway pavement. The advantage and disadvantage of these excavation methods are evaluated based on the monitoring results and construction records. Then a nonlinear 3-dimensional finite element software, PLAXIS 3D, are used to verify the soil engineering properties so that the calculated and measured inclinometer deflections are well matched. Finally this finite element method with the same calibrated material parameters is used to simulate vertical round shaft excavation with shotcrete wall and horizontal beams. The calculated deflection of inclinometer matched very well to the measurement on the site. The monitoring results and numerical results also demonstrate the superiority of vertical round shaft excavation over the other two excavation methods in this formation of clayey gravel with cobble.