Key points of subway construction monitoring?

The key points of subway construction monitoring are very important. Only by understanding the original intention of monitoring can we understand the key points, and the handling of every detail is crucial, so we should pay attention to combining with reality. Zhong Da Consulting will explain the key points of subway construction monitoring for you.

1. Introduction

Since the 20th century, the urban subway in China has developed rapidly. At present, there are 25 cities in the State Council officially approved to build subways, and 10 cities already have subways. From 2065,438+00 to 2065,438+05, the planned investment in subway construction will reach 65,438+065,438+05.68 billion yuan. By May of 20 13, the subway mileage in China has reached 25 18.6Km, the mileage under construction is 2975.58Km, and the planned mileage is 14678.84Km. Hangzhou, Chengdu, Xi and Xiamen are actively applying for or have started to build subways. It can be seen that China's subway has entered a stage of large-scale development.

Because the subway station is generally located in the downtown area of the city, the high-rise buildings near the station are dense and the underground pipe network is complex, the plane size and excavation depth of the deep foundation pit of the subway station are generally about 200 (length) ×20 (width )×17 (depth). At present, the scale of foundation pit in domestic subway stations is increasing, and the surrounding environment is extremely complex, which also brings a series of complex engineering problems, such as the deformation of retaining structure caused by foundation pit excavation and the risk to surrounding buildings, underground pipelines and ground traffic.

Subway monitoring has become an important link in the construction process of stations and sections, and its importance is mainly reflected in the following aspects:

(1) Through the analysis of the field monitoring data, the deformation of the envelope and surrounding environment can be objectively and dynamically reflected.

(2) Through feedback information, reasonably control the construction rhythm on site.

(3) Provide a reasonable basis for design change and construction scheme modification.

(4) Continuously accumulate experience to improve the design and construction level of subway.

With the increasing complexity of modern engineering construction environment, subway stations must be informatization, and on-site monitoring and measurement can provide an important basis for informatization construction. Combined with Xiamen Rail Transit 1 Line, this paper discusses the key points of subway construction monitoring.

2. The basic process of subway construction monitoring

3. Preparation before subway construction monitoring

3. 1 Familiar with design drawings and construction scheme.

Taking Tianshui Road Station as an example, according to the design drawings and construction scheme, the station crosses Tianshui Road, adopts the form of retaining piles and internal supports, adopts vertical excavation, and adopts the top-down construction method under Tianshui Road. According to the Technical Specification for Monitoring of Urban Rail Transit Engineering (GB 50911-2013), the design depth of foundation pit is 18m. According to Table 3.3.2, the risk level of foundation pit engineering is Grade I. ..

3.2 Investigation of the surrounding environment

Investigate the buildings, underground pipelines and municipal roads that may be affected by the foundation pit. Buildings are mainly about the building age, structural form, foundation type and geological conditions, and the current situation of buildings is photographed for evidence collection. Underground pipelines mainly investigate and analyze pipeline function, material, working pressure, pipe diameter, interface form, buried depth, laying method and laying years. As shown in Figure 2, according to the field investigation of surrounding environment, it can be seen from Table 3.3.3 that there are six-story buildings (1# building) and underground pipelines in the main influence area of foundation pit (0.7 times the depth of foundation pit), and the risk level of surrounding environment is determined as Grade II. According to the table 1, it can be determined that the monitoring level of foundation pit in Tianshui Road Station is Grade I. ..

3.3 Investigation on Geological Conditions of Foundation Pit

Consulting relevant literature, understanding the original landform of the station, further mastering the engineering geological and hydrogeological conditions through detailed geological exploration data, and finding bad geology and special rock and soil have an important guiding role in compiling the monitoring plan. In the process of foundation pit excavation, the geological conditions of the excavation surface are compared with the geological exploration data to further optimize the design, construction and monitoring scheme.

3.4 Preparation and audit of monitoring scheme

According to the monitoring grade of the project, the monitoring items and methods, the principle of measuring point layout, the monitoring frequency and the monitoring early warning value of the foundation pit project are determined, the monitoring scheme of the measuring station (interval) is compiled, and the on-site monitoring work is carried out according to the final scheme.

The monitoring scheme mainly includes the following aspects: (1) general situation of the project; (2) Geological conditions, surrounding environmental conditions and engineering risk characteristics of the construction site; (3) monitoring purpose and basis; (4) Monitoring scope and engineering monitoring level; (five) monitoring objects and projects; (6) Layout methods and protection requirements of reference points and monitoring points, and layout of monitoring points; (7) monitoring method and accuracy (8) monitoring frequency; (9) Monitoring control value, early warning level, early warning standard and monitoring measures under abnormal conditions; (10) Requirements for collection, analysis and processing of monitoring information; (1 1) monitoring information feedback system; (12) Monitoring instruments, equipment, components and personnel; (13) quality management, safety management and other management systems.

4. On-site implementation of subway monitoring

4. 1 Monitoring point embedding and acceptance

The measuring points should be buried in the construction site in strict accordance with the arrangement of the measuring points in the monitoring scheme, and some monitoring items need to be buried during the construction of the retaining structure, such as the inclinometer tube required for the deep horizontal displacement of the retaining pile (wall) and the steel bar meter supported by concrete. Other monitoring items that need to be buried before foundation pit excavation. Before foundation pit excavation, all monitoring items shall be checked and accepted, and initial data shall be collected and compared with the third-party data of the construction party to ensure that the initial data are within the monitoring error range.

4.2 Reasonable arrangement of monitoring tasks

There are many on-site stations and monitoring stations, and the monitoring station acceptance ledger can realize the dynamic management of on-site acceptance of each station. According to the monitoring frequency, the station monitoring ledger can reasonably arrange the personnel, equipment and vehicles needed by each station; Improve the monitoring efficiency and avoid missing the monitoring points. The combination of these two accounts can control the workload of on-site monitoring and measurement as a whole. If the measuring points are found to be unqualified or damaged, the construction unit can be urged to bury them in time or take other remedial measures according to the on-site construction conditions, and the initial values can be collected again.

4.3 Inspection of surrounding environment and foundation pit

During the construction of the foundation pit and section of the subway station, special personnel will inspect it every day. The main contents of foundation pit inspection are supporting structure, construction conditions, surrounding environment and monitoring elements. The patrol inspection work is timely, in place and serious, which can not only find and solve problems in time, but also play an important role in supplementing, perfecting and assisting the monitoring and measurement, and gain important basis for monitoring the reasons for data changes while obtaining first-hand information. Patrol and monitoring complement each other, and comprehensively analyze and judge the risks of the main structure itself and the surrounding environment.

Extreme weather such as storm has great influence on the sensitivity of monitoring elements, so patrol should be strengthened and field information should be fed back in time.

5. Data collation and submission

According to the monitoring time stage and the timeliness of the monitoring structure report, the monitoring report is divided into daily report and periodic report. Daily newspaper is the most direct and simple report form to reflect the deformation and change of the monitored object, and it is an important foundation to realize information construction. Periodic reports are mainly in the form of weekly reports, monthly reports and annual reports, which are in-depth summaries and analysis of various monitoring information and monitoring analysis results over a period of time. Through comprehensive analysis, the change law, development trend and evaluation of each monitoring project and the whole project at this stage are obtained, which provides stage guidance for information construction.

6. Conclusions and recommendations

(1) Monitoring and measurement during the construction of urban rail transit is one of the important means to ensure the construction safety.

(2) Urban rail transit engineering monitoring through design drawings and specifications, combined with engineering geological characteristics, as well as the investigation of the surrounding environment, the preparation of a reasonable and targeted monitoring program.

(3) After careful organization, with the efforts of professional technical team, advanced technical equipment is adopted to carry out on-site monitoring and measurement, and timely, accurate and reliable monitoring results are formed to ensure the safety of the engineering structure and surrounding environment.

The detailed information of "Key Points of Subway Construction Monitoring" can be found in the link of Zhong Da Consulting and Design, and all relevant building construction information you want is available.

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