Hidden dangers and Countermeasures of multi tower

Hidden dangers and Countermeasures of multi tower operation in community development and construction

with the development of China's national economy, various buildings have sprung up rapidly. As a three-dimensional vertical transportation tool for construction projects, the use of hoisting machinery is increasing day by day. Tower cranes, especially fixed foundation and trolley luffing tower cranes, are favored by construction enterprises because of their convenient installation and disassembly, site saving, large work coverage, high efficiency and quickness, and play an important role in modern building construction. At the same time, tower crane is a hoisting equipment involving life safety and great danger. If it is used and maintained improperly, the accident will cause a devastating blow to the lives and property of enterprises and people. As tower crane operation belongs to special equipment operation and accidents occur frequently, the Ministry of construction will list it as an important work of special treatment for unemployment. Relevant laws and regulations have been formulated for its design, manufacturing, installation, maintenance, transformation, use inspection, detection and other aspects, so as to strengthen the safety management of tower cranes, prevent and reduce accidents, ensure the safety of people's lives and property, and promote economic development

multi tower operation refers to the simultaneous operation of more than two tower cranes in the same operation area. The focus of this paper is how to safely and reasonably locate the adjacent tower cranes during multi tower operation and how to formulate corresponding measures to ensure its safe operation during multi tower cross operation

I. reasons for the formation of hidden dangers in multi tower operation

at present, some commercial and residential communities developed in cities are contracted by building due to various reasons, which increases the number of construction units and narrows the construction site of each unit of project. During the construction and production process, materials and equipment are piled up and placed disorderly, lines are pulled and led disorderly, and some areas are both vehicle pedestrian passages and workplaces such as steel bar tensioning and processing. Tower cranes stand in the community, interfering with each other, and there is no overall plane layout or reasonable layout at all. Especially in the installation and positioning of the tower crane, some project departments do their own things, only consider meeting their own construction needs, ignore the relevant safety technical regulations formulated by the state for multi tower operation, and do not consider whether the adjacent two towers can rotate 360 ° freely at all, so that the distance between the two tower cranes is less than the length of their jib. In case of strong wind or misoperation, the tower arms may collide, and the machine may be destroyed and people may die, There is no safe production and civilized construction at all

II. How to locate safely and reasonably between adjacent tower cranes during multi tower operation

first of all, see the relevant provisions in 4.4.25 of the national technical code for safety in use of construction machinery (JGJ): when there are more than two cranes at the same construction site, the distance between any adjacent parts (including lifting weights) between the two cranes shall not be less than 2m. The above regulations can be understood as follows: it is allowed that the electronic universal testing machine of two adjacent tower cranes can be used at different heights, but it must be ensured that the vertical distance between the upper and lower parts of the two jibs (including the lifting weight) is greater than 2m, and the distance between the end of the low tower jib and the high tower body is greater than 2m

looking at the construction demand, the design length of most commercial and residential buildings is about 70m. If the tower crane stands in the middle of the building and its rotation covers the working face, QTZ40 tower crane (with a rotation radius of 42m) or qtz315 tower crane (with a rotation radius of 38m) is required to meet the construction needs. The center distance between most buildings is about 30m. In this case, even if two adjacent tower cranes are used at staggered heights, one tower (low tower) must not be able to rotate 360 °. If the two tower cranes are required to maintain a safe distance of no less than 2m from any approaching part, the tower crane cannot stand in the middle of the building, but need to lean towards both ends respectively, so that one third of the working face is not within its lifting range

one of the ways to solve the above contradiction is that the owner takes two or three adjacent buildings as a bidding unit when awarding the project, and a construction unit wins the bid. In this way, the construction party can comprehensively consider that the two buildings share one tower crane or the three buildings share two tower cranes, and carry out efficient, reasonable and safe rubber layout on the front suspension system of the cab on the construction site, so as to ensure the construction demand and avoid mutual interference and collision between tower cranes, Reducing the area occupied by fences and roads and solving various contradictions caused by the narrow site are conducive to safe production and civilized construction. In addition, from an economic point of view, the construction party uses less than one tower crane, and only the entrance and exit fees and installation and demolition fees can be saved by 30000 yuan, and the machine shift fee for data processing is 10000 yuan per month

III. safety management of multi tower cross operation

due to the limitations of practical conditions, in the construction of residential areas, multi tower operation, two adjacent tower cranes are used at random, and the mutual occupation of airspace is inevitable. In this case, the construction unit shall coordinate the relationship between all parties involved in the construction, and reasonably position the safety of each tower crane according to the provisions of the national JGJ on the safety distance of tower cranes. At the same time, the construction unit shall sign an agreement on the safety production management of multi tower crane operation, clarify the safety of both parties, so as to ensure safe production, and make relevant safety technical disclosure to the tower crane driver and commander

safe operation agreement for multi tower operation (for reference):

1. For tower cranes working at night, in addition to the tip setting of projection lights and site lighting facing the working face, anti-collision red signal lights should also be set at the top of the tower and the end of the boom

2. The tower crane must whistle for warning before operation, and then start to release the operated party

3. Let the crane run with no load

4. The cross-border operation shall be carried out according to the actual utilization, and the operator shall let the operator in this field

5. When turning in place, the driver should master the inertia of the boom and cut off the power in advance. It is strictly forbidden to use the brake to force the shutdown

6. When one party works and the other party stops, the non working party shall turn the tower crane to the non-interference place

7. The driver should obey the unified command of a specially assigned person and stop working in case of a strong wind above level 6

8. When stopping the machine, lift the hook to the root of the boom and turn the boom to the wind direction

IV. industry development and requirements

the management body of any industry is gradually improved with the development of the industry, and lifting machinery is no exception. In recent years, according to the characteristics of tower crane accidents, the Ministry of construction has formulated a series of relevant laws and regulations to regulate the behavior of tower crane production, assembly and disassembly, detection and use units. The problems and violations that have been found are being standardized and corrected, and new contradictions and unsafe factors are gradually emerging, because any laws and regulations have their limitations and omissions, which should be constantly improved in practice. Only when the users and managers of special equipment for operation fully grasp the characteristics of the equipment, use causality, find problems, formulate countermeasures, and take preventive measures, can we have less or no problems in safety production. For example, the tower crane is subjected to alternating load in the working process, resulting in impact and vibration (cause), which will cause the connection bolts to loosen and the stress hinge joint weld to crack (result). Therefore, regular inspection (Countermeasures) should be carried out

"bucket law" says that the amount of water in a bucket is determined by the shortest board. Similarly, whether a work safety guarantee system is effective depends on whether we have found the weakest link in the system and taken necessary measures

(Niu Xiaoming, Ge Xiayang)