First, the quality control of drainage pipes
(A) Common quality problems
The quality of the pipeline is poor, there are cracks or local concrete is loose, the compression resistance and impermeability are poor, and it is easy to be crushed or seeped: the pipe diameter size deviation is large, and the pipeline installation is easy to stagger.
(2) Quality control measures
1. Pay attention to the inspection of pipes. The construction unit is required to select pipes produced by regular manufacturers, and check whether the materials such as factory certificate and mechanical test report submitted for inspection are complete.
2. Pay attention to the inspection of pipeline appearance. After the pipeline enters the site, the engineering materials engineer shall conduct visual inspection on the pipeline, and the pipeline shall not be damaged, peeled, honeycombed and cracked, and the pipeline that fails the visual inspection shall not be used.
3. Strengthen the protection of pipelines. Manufacturers should be required to strengthen the protection of pipelines during transportation and installation.
Second, the quality control of measuring unreeling
(A) Common quality problems
Measurement errors or accidental avoidance of the original structure lead to the displacement of the pipeline on the plane, and the slope on the facade is not smooth.
(2) Quality control measures
1. Re-measure the pay-off. After the surveyor determines the location of the pipeline center line and inspection well, it is necessary to carry out re-survey, and the next step of construction is not allowed until the error meets the requirements of the specification.
2. communicate more. If unexpected structures need to be avoided during construction, the supervision unit and the design unit should be required to negotiate, and a connecting well should be added at an appropriate position for straight line connection. The angle of the connecting well should be greater than 135.
Third, the quality control of trench excavation
(A) Common quality problems
In the process of trench excavation, there are often quality problems such as slope collapse, immersion at the bottom of the trench, overbreak at the bottom of the trench, unqualified trench section and so on.
(2) Quality control measures
1. Prevention of slope collapse: According to the soil type and mechanical properties of soil, determine the appropriate slope gradient. In general, the slope gradient of supporting straight groove is 1∶0.05 ... For deep groove, it is advisable to excavate in layers. The excavated earthwork should be properly arranged in the stacking position, generally stacked on both sides of the trench. The distance from the toe of the slope to the edge of the trench is determined according to the trench depth, soil quality and trench slope, and the minimum distance should be1.0m.
2. Control of groove section: determine the reasonable groove section and groove bottom width. Slotting section is determined by such factors as groove bottom width, excavation depth, groove bottom, slope of each layer and abutment width between layers. The width of the trough bottom should be the width of the pipeline structure plus the working width on both sides. Therefore, when determining the excavation section, production safety and engineering quality should be considered to make the slotted section reasonable.
3. Prevent the bottom of the ditch from being soaked by water: During construction in rainy season, closed earth ridges should be piled around the ditch, and drainage ditches should be dug outside the ridges if necessary to prevent rainwater from flowing into the ditch. When digging ditches below the groundwater level or in shallow stagnant areas, the construction unit shall be required to set up drainage ditches and collecting wells to pump water. After the groove bottoms out, the next working procedure should be carried out immediately, otherwise, 20cm soil layer should be left at the bottom of the groove as a protective layer.
4. Prevent the trench bottom from overbreak: When excavating the trench, track and measure the elevation of the trench bottom. When mechanical excavation is adopted, 20cm soil layer should be reserved above the elevation of the design trough bottom for manual excavation. In case of over-excavation, the following measures should be taken: fill it with gravel (or pebbles) to the design elevation, or fill it with soil for compaction, and its compactness is not lower than that of the original natural foundation.
Four, the quality control of flat base pipe socket
(A) Common quality problems
Some construction units pour flat foundation concrete when there is water and silt in the tank; The elevation deviation of flat foundation is great, and the thickness cannot be guaranteed; Pipe joint concrete loss, concrete honeycomb holes and other phenomena.
(2) Quality control measures
1. Prevent pouring flat foundation concrete with mud. If rainwater or other guest water flows into the tank, the silt in the tank should be thoroughly cleaned and sand cushion should be laid to ensure the dry tank construction; If there is groundwater in the tank, drainage measures should be taken.
2. Strictly control the thickness and elevation of flat foundation. Before pouring concrete flat foundation, the elevation of the bottom of the groove and the elevation of the top elastic line of the template should be checked when the formwork is erected, and concrete can be poured only after it is confirmed.
3. Check the strength, stiffness and stability of the pipe socket template. What needs to be particularly emphasized is that the supporting point of the pillar cannot be directly supported on the loose soil layer, and pads or piles should be added to make the template bear the gravity and lateral thrust of concrete pouring and vibrating.
4. Strictly control the quality of concrete. Requirements according to the mixture ratio of blanking, vibrating concrete and vibrating compaction.
Five, the quality control of safety tube
(A) Common quality problems
In a circular inspection well, the pipe head is exposed to the borehole wall for too long or retracted into the borehole wall; The local displacement of the pipeline exceeds the standard and the straightness is poor; The pipeline is staggered in reverse slope.
(2) Quality control measures
1. Correct calculation of pipeline laying length: Determine the pipeline laying length between two inspection wells, the length of the pipeline extending into the inspection well and the reserved space between the two pipe ends according to the specifications. In the process of pipeline installation, it should be strictly controlled to prevent the pipe head from exposing the borehole wall for too long or retracting into the borehole wall.
2. Strictly control the straightness and slope of the pipeline, and take the following measures and check at any time: when installing the pipeline, hang the sideline at the radius of the pipeline, and the line should be tight and not loose; When adjusting the center line and elevation of each pipe, it must be supported firmly with stones, and two adjacent pipes shall not be staggered; Before pouring the pipe socket, the triangular part at the joint between the two sides of the pipe and the flat foundation should be filled with fine stone concrete with the same label as the pipe socket concrete, and then concrete should be poured on both sides at the same time.
Interface quality control of intransitive verbs
(A) Common quality problems
The quality of plastering mortar is poor, and the interface plastering is empty and cracked; Interface with mortar screeding, highlight the inner wall of the pipeline; The barbed wire is not aligned with the pipe joint, the insertion depth of the pipe joint is insufficient, and the length of the barbed wire is insufficient.
(2) Quality control measures
1. Strictly control the construction quality of plastering. Cement mortar should be cut according to the mixture ratio, measured accurately and stirred evenly to ensure the strength and workability of mortar. Before plastering, chisel the outer wall of the plastering part of the pipeline, clean it and brush the cement slurry. When the pipe diameter is greater than 400mm, the second layer shall be plastered; When the pipe diameter is less than or equal to 400mm, it can be plastered at one time; For pipes with a pipe diameter greater than or equal to 700mm, when the joint is greater than 10mm, tape should be attached to the joint of the pipe with thin bamboo pieces, and the mortar in the joint should be filled with tamping, and then layered. After plastering, it should be covered and watered to prevent the plastering belt from cracking.
2. Control the flatness between the inner pipe seam and the inner wall of the pipeline. When plastering pipes with a diameter less than or equal to 600mm, drag them back and forth with sacks or other tools to smooth the mortar flowing into the pipes; For pipes with a diameter greater than 600mm, the internal pipe joints shall be scraped off.
3. Ensure the overlapping length of the barbed wire. The interface between cement mortar plastering and barbed wire shall ensure that the barbed wire is aligned with the pipe seam, and the lap length of the barbed wire and the depth of the wire inserted into the pipe socket shall not be less than 10cm.
Seven, inspection well quality control
(A) Common quality problems
The foundation of the inspection well is poured with water, and the deviation between size and elevation is large; Brick joint of shaft wall, mortar is not full, plastering bulges and cracks; No chute is made or the practice does not meet the requirements; Step, well circle, manhole cover installation does not meet the requirements.
(2) Quality control measures
1. Strictly control the foundation quality of inspection wells. You can't water the cushion and foundation. You must ensure that the geometric size and elevation of the foundation meet the design requirements, and the concrete can not be bricked until it reaches a certain strength.
2. Strictly control the quality of wall masonry. The shaft wall must be vertical, and there can be no seams; Mortar to full, build by laying bricks or stones seam to level off; Plastering should be calendered without hollowing and cracks.
3. Money laundering practices should be standardized. The height of the rainwater chute should be equal to the radius of the main pipe, and the shape of the chute should be a semi-circular arc with the same radius as the main pipe; The height of the sewage chute should be flush with the ceiling in the main pipeline, the lower part is a semi-circular arc with the same radius as the main pipeline, and the upper part is parallel to the shaft walls on both sides, with the same width as the diameter of the main pipeline.
4. Strictly control the installation quality of steps, wells and covers. Gray cast iron pedals should be used, and the installation should be firm. The sewage well pedals should be painted with antirust paint: the installation well ring should be full of slurry, and the manhole cover should match the well ring. Heavy manhole covers must be installed on roads with heavy traffic.
Eight, closed water test quality control
(A) Common quality problems
Fill before closed water test; Inadequate preparation before the exam; The water level of closed water test and the measured seepage time do not meet the requirements; Calculation error of water seepage.
(2) Quality control measures
1. Sewage pipes, rain and sewage confluence pipes and other drainage pipes that require water closure in design must be tested. The closed water test shall be carried out jointly by the owner, the construction unit, the supervision unit and relevant departments, and backfilling can only be carried out after the test is qualified.
2. Check the preparation before the test. Before the test, the nozzle of the branch pipe in the inspection well and the nozzle at both ends of the test section shall be blocked with 240mm thick brick 1: 3 cement mortar, and plastered and sealed. After 3 ~ 4 days of curing, water should be poured into the upstream well. When the water head reaches the required height, check whether the brick plug, pipe body and well body are leaking, and block it if it is seriously leaking. After soaking for 24 hours, observe the water seepage, and the water seepage measurement time shall be no less than 3O minutes.
3. Control the water level of closed water test. The test water level shall be 2m higher than the ceiling of the upstream section of the test section. If the height from the ceiling of the upstream pipeline to the inspection well is less than 2m, the water level of the closed water test can reach the wellhead.
4. Correct calculation of water seepage. In the process of closed water test, all kinds of data should be recorded truly, and the leakage should be calculated correctly according to the specifications. Whether the test is qualified or not, speak through the data.
Nine, backfill soil quality control
(A) Common quality problems
Fill water or backfill soil does not meet the requirements; There is no layered backfill; The compactness of backfill soil is not strictly controlled.
(2) Quality control measures
1. Strictly control the quality of backfill soil. Backfill soil shall not contain broken bricks, stones, concrete fragments and hard clods larger than l0cm; The water content of the fill should be close to the optimum water content. Before returning to soil, light standard compaction test should be carried out to determine its optimum water content and maximum dry density; When backfilling, there shall be no water in the tank, and silt, humus, frozen soil and organic matter shall not be backfilled.
2. Strictly control the thickness of each layer of backfill soil. Trench backfill should be compacted in layers, with the thickness of each layer not more than 30cm. The compactness of each layer of fill should be inspected according to the specifications, and backfilling can be continued only after it is qualified. Both sides of the pipeline are required to be filled at the same time, and the height difference on both sides is not more than 30cm.
3. Strictly control the compactness of backfill soil. The density of the trench chest shall not be less than 90%; The density within 50cm of the top of the pipeline should be between 85% and 88% to prevent the pipeline and cover plate from being squeezed; The density requirement of pipes above 50cm is the same as that of subgrade.
The drainage pipeline project is a concealed project. Only by strengthening the quality control of each link in the construction process can we prevent the occurrence of various quality common faults and ensure the excellent construction quality of the whole project.
I believe that after the above introduction, everyone has a certain understanding of the common problems and quality control measures of drainage pipeline engineering. Welcome to Zhong Da for more information.
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