State regulations on construction monitoring

State regulations on construction monitoring

State regulations on construction monitoring

17/09/2020

Monitoring is the use of machines, equipment, and methods (geodetic or non-geodetic) to monitor and measure the deformation of the work. The task of marine monitoring is...

What are construction deformation and construction deformation monitoring?

Deformation is a common phenomenon for construction works, which is the change in position, shape, and size of a building in space and time under the influence of loads and external forces. . If the deformation value of the work is within the allowable limits, it will not affect the durability of the work and the safety of the users. If the allowable limit value is exceeded, it may cause problems that threaten the safety of the works, property, and users' lives. Deformation monitoring is the use of machines, equipment, and methods ( geographical or non-geographical ) to monitor and measure the deformation phenomenon of the work.

The task of deformation monitoring is to determine the actual state of the structure at the time of monitoring to determine the change in shape, size, and position of the work under the influence of various loads and external forces. Deformation monitoring is a very necessary measure so that we can be fully aware of the actual state of the works, promptly detect the generation and development trend of dangerous geotechnical processes.  to provide solutions to ensure project safety. The data collected during the monitoring helps us to correct the theoretical calculations when designing similar works.

  1. Existing legal documents related to construction monitoring.

1.1. Decree No. 15/2013/ND-CP dated February 6, 2013, on quality management of construction works

This Decree stipulates the quality management of construction works in the survey, design, construction, and acceptance test of construction works; regulations on safety management, problem-solving in construction, exploitation, and use of construction works; regulations on the warranty of construction works.

1.2. Circular No. 10/2013/TT-BXD dated July 25, 2013, detailing several contents on quality management of construction works

The circular clearly states 7 bases for acceptance of construction work, including the results of monitoring, measurement, and related experiments.

- In the 5 contents and order of acceptance of construction work, there is the inspection of actual monitoring and measurement data and comparison with the design requirements. (Article 20). Article 22 stipulating the acceptance of completed work items or construction works to put them into use also stipulates the results of monitoring and measurement as the basis for acceptance, in the content and order of acceptance. There are also specific regulations for checking the measurement and monitoring data books.

1.3. Decree 114/2010/ND-CP dated December 6, 2010, on maintenance of construction works xây

This Decree guides the implementation of the construction law on construction maintenance, applicable to organizations and individuals involved in the management, exploitation, and use of construction works in the Vietnamese territory. For monitoring works, the Decree is clearly stated in Article 13.

- The monitoring of the works is carried out in cases where it is required to monitor the work of the works to avoid the occurrence of incidents leading to disasters in terms of people, property, environment, and other cases according to regulations. at the request of the investor, the work owner, or the authorized person.

- The owner or authorized person shall organize the monitoring and evaluation of the work monitoring results according to the provisions of the work maintenance process. then hire a qualified organization to do it.

- Organizations and individuals performing the monitoring must make a report on monitoring results, and evaluate the monitoring results against the allowable parameters stated in the work maintenance regulations. In case of necessity, the owner or authorized person can hire an independent organization to evaluate the monitoring results.

- Agencies specified in Clause 1, Article 26 of this Decree are responsible for stipulating works and construction parts that are required to be monitored during use.

Based on this regulation, the Ministry of Construction has issued Circular No. 02/2012TTBXD dated June 12, 2012.

1.4. Circular 02/2012 TT-BXD dated June 12, 2012, Guiding some contents on maintenance of civil works, construction material industrial works, and urban technical infrastructure works

This Circular guides Article 26 of Decree No. 114/2010/ND-CP on persons responsible for maintaining works and construction parts that are required to be monitored during the process of exploitation and use. Works and construction parts that are required to be monitored during exploitation and use are specified in Article 3 of this Circular as follows:

- In the process of exploiting and using the works specified in Appendix 1 of this Circular and the works showing signs of settlement, cracking, tilting, and other abnormal signs that are likely to cause the collapse of the works. must be monitored. The parts of the building that need to be observed are the main load-bearing structural systems of the building that, when damaged, can lead to the collapse of the building (For example, the space roof, the main bearing frame system of the building. , stadium stands, chimneys, silos ...)

- Monitoring locations, monitoring parameters, and limit values ​​of these parameters (For example inclined deformation, settlement, cracking, deflection...); monitoring time; the number of cycles and necessary contents shall be specified by the work construction design contractor.

- General requirements for monitoring of works during exploitation and use:

  • Monitoring must be carried out according to the monitoring plan established by the monitoring contractor and approved by the person in charge of maintaining the works.
  • The monitoring plan must specify the measurement plan, measuring devices, layout diagram and structure of landmarks, implementation organization, method of processing measurement data, and other necessary contents.
  • The monitoring contractor must make and report to the person in charge of maintenance on the monitoring results, in which the monitoring data must be evaluated and compared with the limit value specified by the construction design contractor. , the relevant standard. In case the monitoring data reaches the limit value specified in Clause 2 of this Article or shows other abnormal signs, the person in charge of maintenance must organize an assessment of the safety of the work, the safety of exploitation, and the use of the project. take timely remedial measures.
  • Organizations and individuals performing the monitoring must have full capacity conditions of organizations or individuals conducting construction surveys or construction quality assessments.

Specialized officers are responsible for guiding the maintenance and monitoring of works according to the provisions of Article 26 of the Decree on construction maintenance No. 114/2010/ND-CP dated December 6, 2010.

Thus, the current legal documents have quite fully stipulated the purposes, requirements, contents, and tasks of the monitoring work for construction objects that are required to be monitored in service of the public. design, construction, acceptance, warranty, maintenance, and state management of the quality of construction works.

  1. The actual situation of construction monitoring by Geodetic method

Construction monitoring by the geodetic method is observing, measuring, determining the displacement values ​​in terms of shape, position, and external dimensions of the work at different times using machinery and equipment. geodesic.

 

Construction monitoring in Vietnam has been carried out since the 1980s and 1981s of the last century and has received more attention in the past 20 years, mainly monitoring the settlement of works by the hydrological method. geometric standard.

In addition to the legal documents mentioned above, in the current system of standards and standards, there are also 06 standards related to geodetic and geotechnical monitoring:

TCVN 9398:2012 - Geodetic work in construction - General requirements.

TCVN 9360:2012 - Technical procedure for determining settlement of civil and industrial works by geometric elevation measurement method.

TCVN 9399:2012 - Houses and constructions - Determination of horizontal displacement by the geodetic method.

TCVN 9400:2012 - Houses and buildings in the form of towers - Determination of inclination by the geodetic method.

TCVN 9404:2012 - GPS measurement and data processing techniques in engineering geodesy.

TCVN 8215:2009 - Irrigation works - Main regulations on design and layout of monitoring equipment for key clusters of works.

Summarizing and analyzing the results of monitoring by the geodetic method in recent years, some comments can be drawn as follows:

- Regarding legal documents and specialized standards in the field of construction monitoring, which have been promulgated relatively fully and synchronously in ministries, branches, and types of construction objects in the whole area. country. However, in the system of Vietnamese Standards and Standards, there is still a lack of Standards on Geodetic Engineering, including a section on Standards on Monitoring for Construction Objects.

- The intensive training in the field of construction monitoring in universities and vocational schools is still limited (02 to 03 courses). There are only 02 universities that have lectures on deformation monitoring by geodetic methods, while the monitoring by non-geodetic methods has almost no training at any university or vocational training.

- The formulation of monitoring plans for the works is still lacking and incomplete, not fully reflecting the characteristics of the displacement and deformation of the works.

- The procurement and arrangement of construction monitoring equipment is still incomplete, synchronous, and sometimes cannot meet the accuracy requirements for each monitoring object.

About data and monitoring results are often missing, much important information is lost, for example, period 0 is lost, many monitoring data are lost according to the load level, and there are monitoring works. Monitoring results between the two stages of construction and exploitation are often interrupted and discontinuous because benchmarks and monitoring landmarks are often lost or lost during the completion process.

- The analysis, evaluation, and comment on monitoring results compared with the requirements of the design or against the current standards are sometimes done very slowly or not at all, losing all practical significance of the important results. monitoring, many observers cannot analyze and evaluate but do not promptly report to the investor to transfer to the design consultant for an evaluation and timely service for the construction and acceptance and management. construction quality management.

  1. Current status of construction monitoring by non-geographic methods

In recent years, hydropower projects and reservoir dams have been built quite a lot, so monitoring equipment has also been included in the project with a fairly large volume. However, the effectiveness of the monitoring work at the dams is not clear. The general situation of the installation of monitoring equipment in hydroelectric projects using a sensor system (non-geodetic) and its effectiveness in installed hydroelectric projects should be considered and improved. more.

 

- About the type of equipment: Up to now, most of the types of equipment are familiar to the designers and have been proposed to apply almost all of them. The required equipment includes simple domestically produced ones such as settlement datums, black open piezometers of all kinds based on electrical principles, vibrating wires of leading airlines in the US, UK, Italy, and India. has also been used.

- The design and arrangement of monitoring equipment is carried out relatively fully and in detail compared to the provisions of current standards. Devices are installed to collect data on:

  • Dam bottom pressure
  • Stress in the dam body in 2 or 3 dimensions
  • Temperature (concrete dam or roller compacted concrete)
  • Horizontal displacement  or  settlement with depth
  • Piezometers on the bottom of the dam, before and after the bottom waterproofing screen.

These types of monitoring all use devices measuring by resistance (electrical principle ) or frequency ( vibrating wire principle ) and are usually specified for automatic connection for long-term monitoring (except for the type of probe that is only specified). is temporary, such as measuring temperature in concrete). However, in the design documents of monitoring equipment, for some works, the purpose of equipment installation is stated very generally as  "detecting incidents that may occur during construction and according to the behavior of the dam." in the mining process”  without a detailed technical justification that one type of equipment must be used or another, monitoring procedures and measurement cycles for some options are also not specifically mentioned.

- The implementation of construction and installation is done by the third contractor. This contractor provides all information about equipment, detailed construction, and installation drawings design. This is a difficult job for a contractor with strong consulting skills because all hydraulic works are located in attractive areas, the installation of equipment lasts according to the construction schedule, The work is arranged on a large scale, the means of transportation and transportation of materials in the project are very difficult for this type of contractor. Therefore, these contractors often hire a construction unit at the site to do this work but only bring technical staff to guide or install equipment with complicated installation processes.

- The recording of monitoring data is usually done in raw form. For example, the dam bottom pressure gauge is the pressure value, and the strain gauge is the strain value. This should only be considered as a record, in this record only the value shown is the measurement result and the time taken for the measurement.

- Monitoring data is not regularly provided to the monitoring designer but is usually submitted after a long time. Therefore, the effectiveness of the monitoring work is not high. On the other hand, the design work does not give an allowable limit value of the measurements (except for the temperature value), so it is impossible to know the meaning of the measured data. It can be asserted that to achieve this goal, the measurement data needs to be evaluated daily. For example, it is required that the temperature of normal concrete 1 day after pouring does not exceed 50°C, if it is found to be higher when measured, it is necessary to evaluate and review the process or materials used.

- Currently, the monitoring equipment is only applicable to the dam, while in other areas such as slopes, excavation pits, or areas with complex geology, there are potential risks. are not installed for monitoring.

- Knowledge about monitoring equipment is very limited and depends mainly on equipment suppliers, which are commercial enterprises. So many devices when installed are still wrong in principle.

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