1 determination technology principle
The determination of engineering quota follows the principle of being scientific and reasonable and seeking truth from facts, and truthfully records the consumption level of materials and machines at the construction site. 1. 1 clearly defines the measurement content and scope. Quota measurement includes three parts: labor, materials and construction machinery. (1) manual. The labor force in the quota refers to all the personnel involved in the project construction except the construction machinery driver, but does not include the management personnel. The unit of measurement of labor is workday, and a person works for 8 hours as a workday. (2) materials. In determining the quota, building materials are divided into materials that constitute engineering entities and auxiliary building materials. The materials indicated in the standard drawing and general drawing are the materials that constitute the engineering entity, and their consumption is determined according to the drawing design consumption plus reasonable loss. Auxiliary construction materials not shown on the drawings are determined by field measurement, among which turnover materials such as templates and scaffolding are the key points. (3) Construction machinery. Take the machinery used in the project construction as the measurement object. The content and scope of measurement include construction machinery and its full-time drivers. Taking machine-team as the unit of measurement, a mechanical work of 8 hours is recorded as a machine-team. 1.2 Selection criteria of representative survey items How to select survey items is directly related to the availability of survey results and the level of construction consumption. Therefore, two factors should be considered when selecting measurement items. First, the project area and natural environment and conditions, technical standards and construction conditions; The second is the construction technology level, management level and equipment level of the construction unit. And reasonably evaluate the correlation between each influencing factor and the level of building consumption. Before the on-site measurement of railway housing construction project, Changchun, Ningbo, Jingzhou and other 1 1 stations are selected as the measurement objects according to different conditions such as region or region, housing construction structure, construction scale and construction conditions of new or existing lines. The housing construction projects of these 1 1 stations were undertaken by China Railway Construction Engineering Group Co., Ltd., China Railway Construction Group Co., Ltd., China Railway Construction 12th Bureau Group Co., Ltd. and China Railway Electrification Bureau Group Co., Ltd. respectively. 1.3 using scientific determination methods, different determination methods have their own advantages and disadvantages, and choosing scientific determination methods can ensure the accuracy of determination. If site conditions permit, two or more methods can be selected for simultaneous determination to confirm and supplement each other. Commonly used measurement methods include time measurement, digital reality, chart reality, working day reality, survey measurement, expert interview, on-site statistics and so on. The characteristics of several main determination methods are introduced below. (1) Time measurement method. This method has a narrow application range but high accuracy. It is mainly suitable for measuring the working hours consumption of periodic repetitive and cyclic work. After adopting this method, other methods are needed to measure the working procedures outside the cycle separately. (2) Digital realism. This method has a wide range of applications and can be used to measure all kinds of working hours consumption, thus obtaining all the data of working hours consumption. (3) Graphic realism. This method has the characteristics of intuitive and rapid operation, and is suitable for continuous determination projects with heavy workload. (4) Working day realism. This method is a method to study the consumption of various working hours in a shift. It can also be compared with the current quota to find out the shortcomings, so as to revise the current quota. (5) Investigation and determination methods. This method has the characteristics of wide application range and comprehensive data. In the field measurement, in addition to selecting scientific measurement methods, measurement forms are also needed, which is the concrete concentrated embodiment of measurement work. Therefore, the determination of engineering quota for passenger dedicated line and the research institute of railway engineering quota have formulated a unified determination table (see reference 3) to ensure the unification of determination methods and records. 1.4 scientific and reasonable construction organization, practical and efficient technology and construction method. Under normal construction conditions, scientific and reasonable construction organization is the premise to ensure engineering quality and carry out survey work. Railway construction projects are mostly open-air operations, and there are many external interference factors. Different construction conditions have great influence on work efficiency. At the same time, the technology used is also the main factor affecting work efficiency. Therefore, before construction, we should optimize the construction organization and technology, reasonably equip construction machinery, and choose practical and efficient technologies for construction. Take this as the measurement object.
2 Preparation and determination steps of determination work
2. 1 Measurement Work Prepare to set up a working group for on-site measurement of engineering quota and conduct personnel training. Equipped with measuring and recording tools such as tape measure, stopwatch, video recording equipment and notebook computer. 2.2 Collect engineering data and master the construction situation. After entering the selected project construction worksite, communicate and discuss with the person in charge of the project department and relevant personnel first, fully understand the worksite situation, and make a definite plan accordingly, arrange and determine the project, division of labor and schedule. 2.3 Determination Steps (1) Draw and optimize the determination flow chart. (2) determine the composition of the team, including the type of work and the number of people. (3) Determine the mechanical configuration, including the model and quantity of the machine. (4) According to the construction organization arrangement and the characteristics of the worksite, select the determination method. For example, the determination of pile foundation engineering in Ningbo and Suzhou stations adopts time measurement method and working day reality method. (5) Analyze the difference between actual operation and process flow chart, and eliminate unreasonable factors. According to the construction acceptance specification, the qualified ones should be measured and recorded in the construction consumption. (6) Fill in the judgment form and save it.
3. An example of digital realism method for foundation beam formwork construction in Jingzhou Station of Hanyi Railway.
3. 1 Basic information The cast-in-place reinforced concrete for the foundation beam of Jingzhou Railway Station adopts formwork construction, and works in the foundation pit with a depth of1.5m. At this time, it is in the rainy season and the foundation pit is muddy, which brings certain difficulties to the construction. In order to ensure the normal development of construction and survey, the operation team is established according to the routine, and the personnel and construction machinery are reasonably equipped. The quality of materials used meets the requirements of construction specifications. With the development of construction, make records. 3.2 The construction organization shall transport large materials, templates, 5cm× 10cm wood squares, steel pipes and screws. Used in site construction is mainly completed by tower crane, with manual loading and unloading. Due to the tight construction period, turnover materials such as templates and steel pipes cannot be turned over. First, the large foundation beam with 1 ~ 6 axis shall be constructed. After trench excavation, the formwork and steel bar shall be bound. At the same time, the 7 ~ 16 axis is also digging trenches, and the 17 ~ 22 axis is finally digging trenches. 1 ~ 6 axis reinforcement and formwork shall be poured after acceptance. At the same time, carpenters and steel bar workers began the construction of foundation beam formwork and steel bar of 7 ~ 16 axis, and so on. Therefore, all templates, corresponding steel pipe supports and screws are put into use at one time. 3.3 Difference between this measurement and the original railway quota (1) In the original railway engineering quota, the formwork was made of composite steel formwork and composite steel support, but this project actually adopted wood formwork, steel support and wood support. (2) The materials used on site are transported by tower crane; The original railway engineering quota is the consumption of truck cranes, and other machinery also includes some small hand tools. 3.4 Construction process The construction process is shown in figure 1. 3.5 Team personnel are equipped with project worksite and team personnel (excluding construction machinery drivers) as shown in Table 2. 3.6 equipped with mechanical model and quantity. See Table 2 for the model and quantity of mechanical equipment equipped on the project site. The formwork construction of foundation beam in this project (1 site) is determined by digital realism method according to the technological process shown in Figure 1. Time: 201September 15 to 201June 16, * * is 31d. The measured formwork construction area is 608m2, and concrete should be poured 1 34.69m3. According to the requirements of the measuring table1and the technological process, the time and the number of participants were recorded respectively. The record results show that the total consumption time is 265,438+502 min, and the converted man-day consumption is 44.798. 3.7 Problems needing attention (1) In actual projects, the working procedures of construction operations are often different from the established technological methods. When determining the adopted process, it should meet the requirements of relevant design and construction specifications, safety and quality standards and operating procedures, and eliminate unreasonable factors. (2) From the actual measurement process, the formation of some project shifts is relatively clear, such as piling process; Some of them are complicated and need careful screening. (3) Maintain the continuity and integrity of the determination, and explain the special circumstances.
4. Arrangement, analysis, review and acceptance of measurement data
The collation and analysis of measurement data should be complete, unified and standardized, which is convenient for quota compilation and use. 4. 1 When compiling the measurement report, the whole measurement process should be summarized, the measurement situation should be explained, and compared with the current quota, and suggestions for revising the current quota should be put forward. 4.2 Composition of measurement data The composition of measurement data should include measurement work report, overall data of measurement site and individual measurement data. 4.2. 1 Determination of overall data of worksite (1) Implementation construction organization design and special construction scheme; (2) Geological survey report; (3) Construction drawings and construction logs; (4) Comprehensive construction progress indicators of partial projects; (5) Water and electricity consumption of the project; (6) Procurement, supply and recovery of turnover materials; (7) Natural conditions such as climate, altitude and earthquake cracks; (8) Supplementary materials and construction machinery information; (9) Other relevant information. 4.2.2 Description of single measurement data (1); (2) construction process flow chart; (3) composition of shifts; (4) Configuration of construction machinery; (5) Field measurement table; (6) Construction image data. 4.3 After reviewing and analyzing the measurement data, a review and acceptance meeting shall be held, and the expert group shall conduct a comprehensive review of the measurement results. The unqualified items shall be supplemented and inspected, and filed after acceptance, which shall be used as the basic data for preparing the quota.
5 concluding remarks
At present, some professional engineering quotas are divorced from engineering practice to some extent. The main reason is that the field survey is not paid enough attention and the work is not in place. In this paper, combined with the practical work of determining the engineering quota of passenger dedicated line and railway housing construction, the determination of railway engineering quota is analyzed and studied, with a view to forming a set of scientific and systematic determination methods, and providing objective and true basis for the compilation of railway engineering quota and better management of engineering cost.
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