Seeking pipe jacking construction technology

Pipe jacking construction technology Pipe jacking construction is to gradually push the pipeline into the soil with the help of jacking equipment in the underground working pit, and manually or mechanically dig out the soil that hinders the pipeline from moving forward. This method reduces a lot of earthwork and saves construction land, especially when crossing buildings. With the development of urban construction, pipe jacking method has been widely used in underground engineering. The pipe used in the pipe jacking method is generally reinforced concrete pipe or steel pipe, and the pipe diameter is generally 700-2600 mm. The pipe jacking construction mainly includes: the setting of operation pit, the construction of back seat, the laying of guide rail, the arrangement of jacking equipment, the preparation of working pipe, dewatering and drainage, jacking, excavation, and the laying of pipeline and interface. 1. 10. 1 classification of pipe jacking construction at present, pipe jacking construction can be divided into jacking method, jacking method, relay method, back jacking method, traction method, deep covering soil antifriction jacking method and so on. When pipe jacking method is used in underground engineering construction, different pipe jacking methods can be adopted according to the characteristics, design requirements, technical standards and relevant regulations of underground engineering, as well as the actual situation of engineering environment, construction intensity and economic benefits. 1. 10.2 Before determining the pipe jacking construction scheme: (1), the construction unit shall organize relevant personnel to understand the engineering geology and hydrology along the pipe jacking construction and the geological survey report provided by the survey and design unit; Especially familiar with soil types, physical and mechanical properties, stone content and particle size analysis, permeability and groundwater level. (2) Investigate the underground obstacles along the pipe jacking, and take safety protection measures for the upper buildings and structures in the pipeline crossing section. (3) Prepare the organization design scheme for pipe jacking construction of this project, in which targeted and effective safety technical measures and special schemes must be formulated. (4) Establish various safety production management systems, implement relevant norms and standards, define the responsibility system for safety production, define the responsibility system for safety production, and assign responsibilities and responsibilities to specific personnel. 1. 10.3 materials and equipment (1) auxiliary materials such as reinforced concrete pipes and steel pipes used in construction preparation must be qualified. (2) Before pipe jacking construction, used pipe jacking machines and tools (such as oil pump trucks and jacks) must be inspected and maintained before they can be put into use. (3) The position, horizontal and depth dimensions, support mode, structure and scale of the material platform, the structure and installation of the backrest, the treatment of the foundation at the bottom of the pit and the installation of the guide rail, the selection of jacking equipment and the layout of the bottom of the pit shall meet the specified requirements. Especially when the back (bearing wall) bears the maximum jacking force, it must have sufficient strength and stability, and its plane must be perpendicular to the axis of the jacked steel pipe. The allowable deviation of its inclination must be+-5mm/m (4). When installing the jack, it must meet the requirements of relevant codes and regulations, especially the jack should be equipped with 1.2 times of the total jacking force selected by theoretical calculation or experience. Generally speaking, the number of jacks is even. (5) All workers who excavate the working pit shall strictly implement the safety technical disclosure of engineering technicians, and be familiar with the position, depth and trend of various buildings and structures on the ground and underground, as well as the labor protection measures that must be taken when possible hazards occur. 1. 10.4 Precautions for pipe jacking construction (1) Before pipe jacking construction, the underground pipe jacking method shall be adopted. According to the actual situation, formulate special safety technical schemes and measures that conform to specifications, standards and procedures. (2) When installing the back seat of pipe jacking, if it is found that the back wall is uneven or the sleeper is unevenly pressed during jacking, it must be adjusted and reinforced before jacking. (3) When mechanically excavating the earthwork in the upper part of the pipe jacking pit, there should be a special person at the site to command the loading, and the pile of soil should comply with the relevant regulations, and the structures and embedded vertical supports should not be damaged. If the working pit adopts concrete cast-in-place pile diaphragm wall, the relevant safety technical regulations shall be strictly implemented; There must be drainage equipment and measures around the working pit or at the bottom of the pit; The working pit shall be equipped with a safety ladder that meets the requirements and is firmly fixed. During the whole pipe laying operation, when hoisting the jacking iron or steel pipe, no one is allowed to stay within the radius of rotation of the boom in the working pit (4); When the pipe is lowered into the working pit, the safety wire rope should be worn, and the pipe should be slowly sent to the guide rail in place to prevent the pipe from slipping or hitting the guide rail. At the same time, people under the pit should stand in a safe corner (5). Intubation and sealing packing must be handled according to the operation requirements, especially when the tool pipe is in place (the elevation of the center line of the pipeline and the bottom of the front and rear ends of the pipeline should be strictly re-measured to confirm that it is qualified) and when the pipeline is extended. The installation of hydraulic machinery, jack, oil pump truck, high-pressure water pump, grouting system and other equipment must be all normal before opening. (6) Operators of vertical transportation equipment shall conduct safety inspection on various parts of winch and other equipment before operation, and can only operate after confirming that there is no abnormality. Concentrate on the operation, obey the command, and strictly implement the relevant safety operation procedures of winch and lifting operation. (7) The installed guide rail shall be firm and shall not be displaced during use. The two guide rails should be straight, parallel and equal in height, and their longitudinal slopes should be consistent with the design slope of the pipeline. (8) Before splicing sections or stopping due to failure, we should strengthen contact, and timely notify the operator of tool pipe head to stop flushing mud, so as to prevent landslides caused by excessive flushing and suction. And in the process of long-distance jack-up, strengthen ventilation. (9) Mud suction shower blockage, hydraulic machinery failure, etc. Stone holes must be drilled on the chest plate for treatment, and safety measures must be taken to prevent roof caving and collapse. (10) During jacking, the oil pump operator should strictly observe whether the pressure of the oil pump truck increases evenly. If the pressure suddenly rises, stop jacking immediately and continue jacking until the reason is found out. (1 1) The jacking or stopping of the pipeline shall be based on the signal from the tool pipe head. When the jacking system fails or 20 minutes before the pipe splicing, a signal should be sent to the operator of the tool pipe head to attract attention. (12) During jacking, all operators are not allowed to operate on both sides of the jacking to prevent the jacking from collapsing and hurting people. (13) If the jacking operation is not carried out for three consecutive shifts, there should be enough soil plugs at the tool pipe heads after the middle shift; If the soil quality is not good, it may collapse due to groundwater leakage, so the tool pipe head should be filled to increase the water pressure. (14) The lighting communication system in the pipeline shall be safe voltage. Before each shift of pipe jacking, electricians should carefully check whether all kinds of lines are normal to ensure construction safety. (15) The rectifier jack in the tool pipe should be well insulated, and insulating gloves should be worn when operating the electric high-pressure oil pump. (16) During jack-up, measures should be taken to prevent gas, fire, explosion and water. When the jacking length exceeds 50M, measures should be taken to prevent hypoxia and suffocation. (17) Oxygen cylinders and acetylene cylinders (cans) are not allowed to enter the pit.