受到新建結構物施工之周邊地層位移影響，以致鄰近既有結構物之安全性或功能性有疑慮的工程施工，謂之「鄰近施工」，英文字意有採Adjacent Construction、 Neighboring Construction 及 Close Construction 等用法，過去國內工程界亦有沿用日本專業術語 「近接施工」之用法。在人口及建物密集之都會區為主的地下結構工程建設，諸如建築物地下室或基礎、高架橋基樁、捷運隧道、大型上下水道或地下管道等之地上以及地下結構物，未來勢必經常遭遇毗鄰既有結構物之環境下施工，所面臨的施工條件愈益嚴苛，為期在既有結構物不受到有害影響下，安全且合理的進行新建工程之調查、設計、施工以及維護管理等，編輯委員會特規劃出版本專輯，以饗廣大讀者之殷切需求。
Urban developments are often carried out in congested area with limited space. Construction sites adjacent to existing structures are liable to induce ground movement that may cause structural damages. Protection of buildings close to any underground MRT construction sites become a must nowadays. However, once the MRT structures are completed, they may themselves be influenced by future new engineering activities along the MRT lines and hence needed to be protected. Therefore continual interactions among new sites with adjacent existing structures are important topics for recent geotechnical studies. This Paper introduces the basic concept of neighboring construction in civil engineering works that may likely induce ground movement, such as deep excavation, shield tunneling. piling, diaphragm wall trenching and dewatering of groundwater etc. This Paper suggests that the types of structures, their locations as related to the construction site should be critically reviewed and classified. Major items for review and implementation procedures are established. Other major topics like evaluation methods of the extent of influence to structures, construction strategy used to minimize possible damages and instrumentation monitoring are also included. Two local case studies are reported to demonstrate (a) the influence of shield tunneling on a bridge pier and the protection technique used, and (b) selection of construction procedures to reduce the cross influences between two adjacent deep excavation sites.
This paper presents an evaluation procedure for estimating movements of retaining system and ground caused by adjacent underground construction in clayey soils and also evaluating the damage potential of existing buildings adjacent to the site. The evaluation procedure includes three steps: (1) estimate excavation-induced wall deflection and vertical and lateral movements; (2) estimate ground movement-induced building deformation considering the soil-structure interaction effect; (3) evaluate the damage potential of buildings based on the estimated angular distortion and lateral strain of buildings. For upgrading the efficiency of evaluation, all methods included in the three steps have been formulated and incorporated with the reliability concept. The analytical results could provide more complete information to engineers for decision making.
In this paper, the authors summarized the construction strategies and management for close construction such as deep excavation, soft ground shield tunneling, deep foundation and soil improvement. Purpose of this paper is hoped to be helpful to those engineers who encountered related challenges.
With ample road width, tunnels were constructed at least 6 meters apart, and open-cut stations were at a good distance away from adjacent buildings for the first stage of Taipei MRT. For later stages of Taipei MRT, some tunnels and stations were restricted by the road width, therefore spacing between tunnels was reduced, and stations were excavated near adjacent buildings. Since then, close-up construction had become a very important issue at both design and construction stages. Some close-up cases of Taipei MRT regarding tunnel and station construction are reviewed discussed in this article. The results may be helpful for the planning and design of similar cases in the future.
Since the opening of Taipei MRT system, in Taipei metropolitan area, the development of the private buildings and public construction along the MRT route has been booming vigorously. However, the said construction actually brought great threat to the security of the MRT facilities. In order to ensure safety of the MRT relevant facilities and to protect land developers’ benefits, the Department of Rapid Transit Systems (DORTS) has set up a comprehensive control system of “prohibition and limits of construction”, which made the review operation more standardized and systematized. So far, the said system has been implemented successfully and smoothly by relevant MRT administration units and the public. This article aims to introduce the legal structure and other important content of the said system.
At present, DORTS has accumulated many practical examples of which received great impacts from the development projects carried out near the MRT construction “prohibition and limits of construction” area. Among them the bored tunnels bear the greatest ones. This article will take a number of six impacted bored tunnels as examples and discuss the effect of protective measure to each case. It is expected to provide valuable information to the similar construction projects as reference.
Due to the importance and high standards of management values HSR, it is a key issue of the present management of HSR adjacent construction to grasp the factors possible to lead to HSR structural displacement precisely and definitely by severe control measures. The current construction cases of safety for HSR with no special control required are listed as general engineering cases to develop directly whilst those identified unsafe are listed as controlled subjects with necessary management. The control measures include 3 control phases (1) license application and design, (2) construction start application and (3) under-construction and final settlement application. The monitoring measures indicate that the construction authority shall, during the under-construction period, adopt the “automated real time monitoring system” and have the independent third party appraise the initial values of automated monitoring system, check the accuracy of monitoring data and result analysis and identify the final deformation of construction on HSR structural facilities, which are the HSR automated real time monitoring measures. Due to the deficient understanding of governments at all levels and construction companies about the current enforced related operating regulations, the license application and development schedule will be impacted; moreover, the direct development and construction without authorization in restrained areas or construction not in compliance with approved plans has become the potential factor to damage the HSR operation safety. This paper introduces the application procedures and control measures of design to construction of HSR adjacent construction and illustrates the necessity of control and management concerned by case study.
The Xinzhuang line and thd Xinyi line intersect at Dongmen Station, with two of the four tunnels connecting to Guting Station on the Zhonghe line and the other two stretching to Chiang Kai-shek Memorial Hall Station on the Danshui line. Due to topographical considerations, the crossing of the four tunnels was built beneath Hangzhou South Road near Zhongzheng Junior High School. The closest any of the tunnels come to each other is approximately three meters. As the tunnels extend out in an S-shape with a minimum radius of 200meters, grouting ground treatment had to be completed before excavation. After excavation is completed,the tunnel needs to be protected before proceeding with the subsequent construction. By examining the difficulties of constructing Taiwan’s first-ever crossed tunnels, this article aims to gain valuable suggestions from precursors in related domestic industries so as to assure a safe and efficient completion of construction.
Constructing shield tunnels near existing structures such as passing underneath buildings, bridges or railways has become more and more common in metropolitan rapid transit projects. For these works it is quite essential to assess the construction impact level, adjust drilling parameters by feedback analysis, arrange monitoring systems based on the behaviors of the existing structure and perform protection countermeasures such as ground improvement. Some cases of the shield tunnel construction near existing structures in Kaohsiung Metropolitan Rapid Transit project will be introduced in this article as a reference for similar projects in the future.
This paper introduces the variety, characteristic and application history of underpinning adopted when the new underground structural passing through the existing structure of being operation. The adjacent construction is getting increasing as the more intensive future transportation systems will be built. In view of this, this paper integrates the new trend of underpinning applied on the adjacent construction in Japan. In addition, two underpinning case studies are included in this paper. It is expected that the underpinning described in this paper can be served as the reference basis of future engineering protection project.
The Neighboring constructions of local structures increase everyday. The result of this type of constructions should be investigated beforehand. Then, the degree of influence should be evaluated and last, the construction method and construction Machinery should be decided. This study investigates the construction equipments and tools used, foundation work, retaining wall work and ground improvement work to provide information for investigations of similar future works.