This paper expounds the common problems in various stages of forestry ecological engineering supervision and their causes, and puts forward some solutions or countermeasures for each process.
Forestry ecological engineering supervision generally goes through seven processes from the joint review of design drawings to final acceptance. In the perennial supervision work, it is found that various problems often appear. It is of great significance to summarize and analyze the causes of the problems and the methods to solve them.
1 Frequently asked questions in each stage of project supervision process
1. 1 Operation design and construction design, as well as the joint review of drawings.
The most common problem in the process of drawing review is that individual designed tree species are not suitable for local site conditions, and some designed tree species violate the ecological characteristics of tree species. For example, conifers (including some broad-leaved trees) are designed to be planted in saline-alkali land with soil PH above 8.0 or in areas with high viscosity of red clay and black clay and thick calcium layer, resulting in low survival rate of seedlings after planting, and even all of them die in the next year. The reason is that the designers are pressed for time, and have not made a detailed investigation and understanding of the site conditions in the project area, especially the physical and chemical properties of the soil and the thickness of the soil layer (the surface layer is agricultural land, and the soil around 30cm is suitable for crop growth, while the soil below 30cm is becoming more and more sticky, which is not suitable for forest growth). Incomplete understanding and blind design.
1.2 fixed-point pay-off stage
The most common problems of fixed-point setting-out in construction are: inaccurate fixed-point setting-out will affect the landscape effect (especially landscape forest) after seedling planting. The reason for the problem is that the fixed-point setting-out measuring tool (measuring rope) used is inaccurate and the operator's sense of responsibility is not strong. Some measuring ropes are of poor quality, and the longer they are used, the greater the error.
1.3 soil preparation and pit excavation stage
The most common problems in land preparation are: 1. The specifications of land preparation can't meet the requirements of operation design (design drawings), especially when the excavator (hook machine) digs the pot bottom pit with big top and small bottom. The main reason is that in order to save the construction cost, the construction unit only wants to dig a lot of pits without paying attention to quality. Second, when digging a pit by machine, the surface soil and core soil are mixed together. In order to save trouble, the manipulator does not separate the topsoil and subsoil as required.
1.4 planting stage
First, it is easy to appear when checking seedlings before planting: ① the specifications of planted seedlings (diameter, crown width, root system, seedling height, layer height, soil ball, etc. ) can not meet the design standards; (2) The seedlings are seriously dehydrated, and the roots are dry (hairy), so the seedlings are not easy to survive after planting; (3) Not adjusting the seedlings within the scope specified by Party A, resulting in a large number (or all) of seedlings not adapting to the natural conditions in the project area; ④ Incomplete seedling "two certificates and one sign" or "three certificates and one sign"; ⑤ The local authorities do not attach importance to the quarantine of pests and diseases, and the local forest protection departments do not re-examine. Second, common problems in seedling planting: ① When planting, the topsoil is not placed underground when digging holes, but the core soil and topsoil are mixed.
② Do not disassemble the soil ball package; (3) When planting trees and burying soil, large clods (large clods that have not been thawed in spring or frozen in early winter) are not layered and buried in the tree planting pit, resulting in the poor combination of soil and seedling roots, which affects the survival of seedlings; (4) After large-scale seedling raising, the windproof bracket was not tied in time, but watered first and then tied, which caused the seedlings to lodging, damaged the roots and soil balls of the seedlings during righting, and affected the survival of the seedlings; (5) Not watering in time after planting, not watering with planting or insufficient watering will affect the survival of seedlings; 6. Seedlings are not planted with unloading, but exposed to the sun after unloading, resulting in low survival rate or death of seedlings due to a large amount of water loss.
⑦ After watering, soil was not covered in time to prevent water evaporation, resulting in low survival rate of seedlings; ⑧ Not checked after binding the brackets, and the binding quality is not high, resulting in one or two of the three brackets not touching the ground, which does not play a windproof role; Pet-name ruby didn't finish the planting task as planned, and couldn't reach the project schedule agreed in the construction contract. The main reasons for the above problems in the planting process are the shortage of labor and machinery in the construction unit, the lack of technical personnel and low professional quality, poor sense of responsibility, lack of technical guidance in the construction site, failure to carry out construction according to the construction organization design, operation design and construction drawings, and failure of supervisors to conduct on-site supervision, inspection, inspection and acceptance according to the operation design and construction drawings, and lack of technical guidance and responsibility.
1.5 tending and maintenance stage
The most common problems in tending and maintenance stage are: ① watering is not timely, the water ring is broken and not repaired, and the seedlings die of lack of water due to insufficient watering; (2) Broad-leaved trees (trees) do not germinate, the woodland is overgrown with weeds, and the grass seedlings (shrubs) are tall, so the competition for water and nutrients of grass seedlings affects the survival and growth of seedlings; (3) Do not pay attention to forest protection, resulting in human and animal hazards, pests and diseases, fires, etc. The reason for the above problems is that the construction unit is the provincial contract fee. After the planting work, the number of construction personnel is greatly reduced, resulting in less watering personnel, untimely watering, insufficient water, poor water ring repair, no forest guards, no pest control and no patrol during the fire season.
2 solutions
2. 1 Understand the site and correct the design errors of tree species in time.
Before the project starts, the supervision engineer must inspect the construction site step by step to understand and analyze the site situation. During the joint review of design and construction drawings, the supervision engineer should put forward suggestions for changing the unreasonable tree species that are not suitable for local site conditions, such as changing the tree species to shrubs that are more suitable for local growth.
2.2 Strict fixed-point defense, put forward specific requirements.
First, the tool used for defense must be a steel tape measure. The second is to strengthen the responsibility consciousness education for construction workers. Third, according to the operation design standards, supervisors must patrol and check, stand by and correct the problems in time, otherwise they will not be measured.
2.3 According to the design requirements, measure the quantity of soil preparation.
In the stage of soil preparation, the supervisor shall conduct measurement and acceptance in strict accordance with the operation design specification. If it fails to meet the design standards, it must be reworked, otherwise it will not be measured. For mechanical soil preparation, the supervisor will stand by and supervise, and strictly require the manipulator to separate the topsoil and subsoil when digging the pit. If the manipulator does not change, it can be rectified by issuing a "supervision notice" (including those that do not meet the design specifications).
2.4 Strengthen the acceptance and supervision of planting seedlings.
First, supervisors should be familiar with the progress and quality measures of operation design and construction organization design, improve the professional quality of technicians on the construction site, and conduct professional training before construction. The second is to urge the construction unit to ensure the quantity of labor and machinery and ensure that the construction tasks are completed according to the construction progress. Third, check seedling size in strict accordance with the operation design standards. Unqualified seedlings and seedlings without "two certificates and one sign" shall not enter the construction site. 4. The seedling source must be the seedling adjustment range specified by Party A (the construction unit). It is more appropriate to consider the seedling adjustment range (seedling source) in the central and western Inner Mongolia Autonomous Region as the area west of Chifeng, east of Jiuquan in Gansu, Datong in Shanxi and north of Yulin in Shaanxi. But it's best to use local seedlings.
The supervision engineer can judge the origin of seedlings according to their growth, soil (soil ball) and quarantine certificate. Fifth, in the planting stage, the supervisor must conduct a comprehensive inspection and inspection, and the seedlings must stand by before and after into the pit, and supervise whether the soil ball packaging is removed, whether it is practical after filling, and whether there are stones or large clods when covering the soil. Sixth, the supervisor should check whether the windproof support is bound in time after planting coniferous seedlings (seedling height is greater than 1.5m), and urge the construction unit to bind the windproof support in time. At the same time, after all seedlings are planted, make water rings (weirs) and water them in time, so that they can be fully watered, and cover the soil in time to preserve moisture after water infiltration.
Seventh, after the qualified seedlings are unloaded, urge the construction personnel to plant them in time. Seedlings that can't be planted on the same day must be kept moist, and shrubs must be cut off according to the design height. Eighth, after the planting work, the supervisor must conduct a comprehensive inspection tour (1 every 10~ 15d), and notify the construction unit in time or send a supervision notice for rectification when problems are found. Nine is to require the construction unit to leave enough construction personnel after the planting work, and the supervisors should also inspect the forest land frequently (not less than half a month) to monitor the water shortage of seedlings, the growth of weeds, the germination time of broad-leaved trees, diseases and insect pests, and the harm to people and animals. , and promptly notify the construction unit and the construction unit to take effective measures to ensure the survival and growth of seedlings.
3 other stages
3. 1 engineering quantity signing stage
When signing quantities, the most common problem is that one of the three parties (supervision, construction and Party A's representative) lacks signature, especially Party A's representative. Therefore, after the inspection, acceptance and measurement (approved by the three parties) are completed, all parties must sign off immediately, and any problems must be solved on the spot (overnight is not allowed), otherwise the work will be delayed again and again, which will bring unnecessary trouble to future audits.
3.2 Completion acceptance stage
The most common problem at this stage is that the construction unit does not conduct self-inspection, or the self-inspection quantity (engineering quantity) is greater than the actual quantity (measurement is usually controlled by the supervisor). The supervision engineer must urge the construction unit to conduct self-inspection, put forward the self-inspection report, conduct initial inspection according to the self-inspection report, and conduct spot checks. When the error between the self-inspection quantity and the quantity mastered by the supervisor is less than (5%), the supervisor will countersign and apply to Party A for inspection. At the same time, urge the construction unit to sort out the construction materials, and submit them to the construction unit for completion acceptance after passing the examination by the supervisor.
3.3 Data collation stage
Construction units are most likely to miss items when sorting out data. At the beginning of the project construction, the supervision engineer urges the construction unit to set up full-time librarians, and all materials must be registered and filed, and the supervision engineer should supervise and inspect regularly or irregularly.
The above are collected and sorted by Zhong Da Consulting Company.
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