Based on the experience accumulated in Beijing subway construction for many years, the author analyzes the risk management of underground rail transit engineering for your reference only.
Characteristics of underground rail transit engineering Underground engineering has the following characteristics: great concealment. The operation is cyclical. The working space is limited. The mechanical state is changing in the process of dynamic construction, and the mechanical and physical properties of surrounding rock are also changing. The working environment is harsh. At the same time, underground engineering has a great impact on the surrounding environment, which will cause such effects as vibration, surface subsidence, noise and changes in groundwater conditions.
Urban rail transit has several remarkable characteristics, namely, the surrounding environment is complex, there are many buildings and underground pipelines, and the requirements for construction deformation control are high; Engineering geology and hydrogeology are complex, with many uncertain factors; There are many structural forms, many cross-transformations of construction methods, and the construction is difficult. The construction period is under great pressure, etc. These characteristics are concentrated in the high risk of the project. In order to complete the construction task safely, with good quality and quantity, it is necessary to carry out systematic management on the risk and safety of the project.
The main contents of project risk management include: risk identification, estimation, evaluation, countermeasure monitoring, etc. First of all, it is necessary to identify risk factors, understand and determine what risk factors may exist in the project, what impact these risk factors will bring to the project, and what are the specific reasons. At the same time, combined with the estimation of risk degree, we can know the main risk factors of the project. Secondly, according to the probability of possible risks, the degree of difficulty that may increase the project, the loss of personnel and property, the social impact and the impact on the construction period, etc.
Do a good job in basic work and effectively prevent risks. After correctly identifying the risk factors in all aspects of the project, measures should be taken to avoid and prevent risks from the scheme design.
First of all, on the basis of reviewing the construction drawings and methods, we should identify and study all kinds of risk points in the construction of this bid section according to the surrounding environment, make qualitative evaluation and classification, and formulate corresponding emergency plans, so as to do a good job in the dynamic risk management of the project.
Dynamic monitoring of identified risk points in construction is an important content of subsequent risk management. Through dynamic management, standardize the information transmission in construction management, and enhance the risk awareness and scientific management awareness of all parties involved in the construction, especially the construction unit. The dynamic management of major risk points should be carried out with the construction unit as the main body, which mainly includes advance prevention and preparation, process monitoring and control, and information management of known and predictable risk points above AA in different construction stages.
The following points should be done in advance preparation for major risk points:
1. Prepare and approve the special plan and emergency plan for major risk points. The construction unit shall dynamically identify the risk points according to different construction stages. For known and predictable major risk points, a detailed special construction plan must be prepared. In the plan, the materials, quantity and specifications of machines and tools, personnel preparation, water and electricity preparation, information contact methods, etc. required to pass through the risk point should be clearly defined. The scheme shall be demonstrated by the enterprise or external experts one month before the risk point and submitted to the chief supervision engineer for approval. At the same time, in order to strengthen the timely control of risk points, the construction unit should comprehensively count and sort out the basic situation of risk points and actively make preparations in all aspects.
2. For the contents of major risk points, the preparation for external coordination should contact and coordinate with relevant property rights units and transportation and municipal departments 15 days in advance, strive for the understanding and support of relevant units, and fully make necessary preparations and cooperation.
3. Full participation in dynamic risk management should establish a training and disclosure mechanism for dynamic management of major risk points, so as to ensure full participation in dynamic risk management. According to the identified major risk points and special construction plans, the chief engineer of the construction unit must be responsible for organizing the management personnel above the section chief and team leader of the unit to carry out training, education and technical disclosure on risk management procedures and special plans. The section chief and team leader shall organize the training for the on-site construction operators. Training should be recorded and written disclosure should be clear.
4. Appropriate risk points, process monitoring and information feedback during the construction of risk points, measures should be adjusted in time according to the engineering characteristics, corresponding early warning values and replacement values should be formulated according to standards, and construction should be strictly guided by monitoring measurement data. When the warning value is reached, the construction unit must report it step by step according to the procedure, and immediately prepare to start the emergency plan. In the implementation process of risk points (such as underground construction crossing bridge piles, pipelines, building foundation side, water seepage in tunnel face, serious local collapse, etc.), established schemes and measures should be strictly implemented to strengthen the quality control of each working procedure, ensure the safety of working procedure T, and thus ensure the safety of the project. Therefore, the supervision unit should strictly supervise and control the scheme, conduct special research with all parties in time, and solve practical problems in construction.
5. Establish a dynamic management file of risk points. The dynamic management file of risk points should include the following contents: the preparation of prevention and control plans and emergency plans for major risk points, including the identification of major risk points in different construction stages, special plans and emergency plans, as well as the implementation procedures, organization, materials and equipment, and the contact information of relevant units and personnel. The approval record of the scheme; Records of preparation before the implementation of risk points. Record of implementation process of risk point. Summary of experiences and lessons after all risk points are avoided, including: the surrounding environment of risk points, main construction methods (summary of main technical parameters and main materials should be detailed), time spent in avoidance, monitoring and measurement data and other relevant data, construction technical measures and scheme implementation during risk passing, etc.