Common quality problems in road engineering and preventive measures
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Common quality problems in municipal engineering and their prevention
& lt drainage section >
Municipal road drainage system is one of the important facilities for the normal use of urban municipal facilities, and it is very important to ensure its construction quality. The common quality defects in municipal drainage pipeline construction are divided into four aspects, the causes are analyzed and the preventive measures are put forward.
A, pipeline position deviation or water
(1) Reason:
Measurement error, construction deformation and accidental avoidance of the original structure will all cause plane position deviation, water accumulation in the facade and even slope reversal.
(2) Preventive measures:
1. The main measures to prevent and measure construction diseases are: (1) Before construction, the handover piles should be re-measured and protected according to the construction survey specifications and procedures. (2) Construction lofting should be combined with hydrogeological conditions, conform to the buried depth, design requirements and relevant regulations, and the error must be re-measured before delivery. (3) In strict accordance with the model pile construction, do a good job in measuring and accepting the axis and longitudinal slope of the foundation trench and foundation.
2. In the process of construction, if it is necessary to avoid structures accidentally, a connecting well should be added at an appropriate position and connected in a straight line, and the angle of the connecting well should be greater than 135.
Second, the pipeline leakage, closed water test is unqualified.
(1) Reasons
Uneven settlement of foundation, poor construction quality of pipelines and their joints, poor sealing at the end of closed water section and poor construction quality of well bore may all cause water leakage.
(2) Prevention and control measures
1. Poor pipeline foundation conditions will lead to uneven settlement of the pipeline and foundation, generally causing local water accumulation, and in severe cases, pipeline fracture or joint cracking will occur. Preventive measures are: (1) Carefully construct according to design requirements to ensure the strength and stability of pipeline foundation. When the hydrological conditions of the foundation are not good, soil replacement should be carried out to improve the bearing capacity of the bottom of the foundation trench. (2) If the soil at the bottom of the trough is disturbed or soaked by water, the soft soil layer should be dug first, and then the overbreak part should be backfilled and compacted with stable materials such as miscellaneous sand or gravel. (3) When excavating earthwork below the groundwater level, effective measures should be taken to prevent drainage and precipitation at the bottom of the trough to ensure the excavation of the dry trough. When necessary, a soil layer with a thickness of 20cm can be reserved at the bottom of the pit, which will be removed with the excavation of the subsequent process.
2. The quality of the pipeline is poor, there are cracks or local concrete is loose, the impermeability is poor, and the capacity leaks. Therefore, it is required that: (1) the pipes used should have the certificate and mechanical test report provided by the quality department; (2) The appearance quality of the pipe requires that the surface should be smooth, and there should be no loose appearance and honeycomb pits; (3) Check it section by section again before installation. For those who have found or have quality problems, they should be ordered to leave or be effectively treated before use.
3. The filler and construction quality of the pipeline interface are poor, and the pipeline is damaged or the interface is cracked under the action of external force. Precautionary measures: (1) Select interface filler with good quality, and organize the construction according to the test mixture ratio and reasonable construction technology; (2) During plastering construction, the joints shall be cleaned, and the hair shall be cut when necessary, and then the construction shall be carried out seriously according to the construction operation procedures.
4. The construction quality of the inspection well is poor, and the joint between the shaft wall and its connecting pipe leaks. Precautions: (1) Masonry mortar for inspection wells shall be full, and jointing shall not be missed; Before plastering, the surface shall be cleaned and moistened, and when plastering, the slurry shall be polished and maintained in time; In case of groundwater, plastering and jointing shall be completed in time with masonry, and internal plastering or jointing shall not be carried out after backfilling; (2) The outer surface of the pipeline connected with the inspection well should be wetted and evenly brushed with a layer of cement slurry, and then plastered inside and outside after the cement slurry is solidified in place to prevent leakage.
5. The branch pipe seal reserved in the plan is not dense, which is often ignored because it is in the well. If brick wall is used for plugging, the following points should be paid attention to: (1) Before plugging, the inner wall of the pipeline within 0.5m of the nozzle should be cleaned, and the cement slurry should be painted to wet the bricks for later use; (2) The mortar label shall be no less than M7.5 and have good consistency; (3) The label of cement mortar for jointing and plastering shall not be less than M 15. When the pipe diameter is large, only when the pipe diameter is large, the inside and outside sides should be jointing or plastering. Plastering should be carried out according to the waterproof five-layer construction method. (4) In general, sealing should be carried out before manhole laying to ensure quality.
6. The closed water test is a comprehensive inspection of pipeline construction and materials, and it is inevitable that there will be three or two unqualified phenomena during this period. At this point, the leaking places should be marked one by one, and the water in the drain pipe should be carefully treated. For tiny cracks or pit leakage, cement slurry or waterproof coating can be used, and serious rework is required. In addition to replacing pipes and re-caulking, serious leakage can also be handled by professional and technical personnel. After treatment, do another test, and so on until the water is closed and qualified.
Three, inspection well deformation, subsidence, poor quality of components.
(1) Reasons
The manhole is deformed and sunk, the quality of the manhole cover is poor, the installation quality is poor, and the ladder in the well is installed at will, which affects the appearance and use quality.
(2) Prevention and control measures
1. Do a good job of checking the foundation and cushion of the well, and break the pipe to make a chute to prevent the well from sinking.
2. Check the masonry quality of the well, control the center position and height of the well chamber and wellhead, and prevent the deformation of the well bore.
3. The manhole cover and the seat ring should match; When installing, the seat slurry should be full; The light and heavy models and the bottom of the face are good. The position of the first step of climbing iron installation should be well controlled, the deviation should not be too big, and the plane position should be accurate.
Four, backfill soil subsidence
(1) Reasons
The backfill around the inspection well is not dense, and it is not compacted by layers as required. The poor quality of filler and poor water content control affect the compaction effect, resulting in excessive post-construction settlement.
(2) Preventive and therapeutic measures
1. Preventive measures. (1) When backfilling the pipe trench, it is necessary to select appropriate fillers and compaction machinery according to the backfilling location and construction conditions. (2) When the groove is narrow, manual or frog rammer can be used for tamping. Different tamping tools should be selected for different fillers and different filling thicknesses to achieve the most economical compaction effect. (3) The silt, roots, turf and decaying plants in the filler not only affect the compaction effect, but also shrink and decay in the soil to form holes. These materials should not be used as fillers to avoid sedimentation. (4) controlling the water content of the filler to be about 2% higher than the optimal water content; In case of underground water or after rain, drainage must be carried out first, and then layered filling and compaction must be carried out.
2. Treatment measures. Take corresponding measures according to the degree of settlement damage: (1) A small amount of settlement that does not affect other structures can be left untreated or only treated with surface treatment, such as local filling on asphalt pavement to avoid water accumulation; (2) If the foundation of other structures is damaged by void, it can be filled by pumping cement slurry; (3) When the structure is damaged, the bad filler should be removed, and the material with good stability should be replaced, and the damaged structure should be restored after compaction.
Verb (abbreviation of verb) conclusion
The pipeline project is a concealed project, and can only be inspected by inspection wells after completion. Therefore, the construction quality of inspection wells often affects the evaluation of the overall project quality, and professional teams should be used to carry out the construction of inspection wells. In a word, the Excellence of drainage pipeline engineering must be based on the Excellence of main structure engineering. In the process of construction, efforts should be made to overcome various common faults, ensure the overall construction quality of the project is excellent, and then make the construction quality of inspection wells better, so as to achieve the purpose of creating excellence.
& lt road section >
First, the roadbed soil is too wet or there is a "spring" phenomenon.
1. phenomenon: the water content of subgrade soil layer exceeds the optimum water content for compaction, which makes most or part of it elastic and soft.
2. Treatment method: (1) When soil subgrade is constructed in rainy season, rainy season construction measures should be taken, and the excavation section should be dug to the height of the road groove on the same day, and it will be crushed to survive every day, while the drainage ditch is dug; When filling the pavement, it should be rolled with the paving, and it will survive once a day. Soil soaked by rain should be dried or replaced.
(2) Avoid filling cohesive soil in subgrade soil layer.
(3) If the subgrade is elastic and soft after grinding, it should be thoroughly excavated and replaced with soil with appropriate water content.
Second, the connection between the pavement slab and the top surface of the vertical kerb is not smooth.
1. phenomenon: there is a relative height difference between the pavement slab and the top surface of the kerb, some of which are higher than the kerb and some are lower than the kerb, generally between 0.5~ 1.0cm.
2. Precautions: (1) If kerbs are erected first, the elevation and flatness of the top surface of kerbs should be strictly controlled. When paving the slate, the elevation of the low point of the trail should be based on the height of the top of the kerb to push the slope upward.
(2) If the pavement slab is paved first, the position and elevation of the kerb axis should be accurately controlled, and the low point of the pavement slab is still subject to the elevation of the kerb top at this position. When the kerb is erected, the elevation at the top of the kerb is connected with the paved pavement slab.
Third, the edge of the paving slab collapses
1. phenomenon: the track slab near the back of the vertical curb sinks, especially at the end of the trail, and there are many sinking phenomena behind the vertical curb at the intersection.
2. Precautions: All parts along the back of the post-standing stone and post-standing stone shall be compacted by layers with a small rammer near the optimum water content.
Fourth, the vertical and horizontal joints of the sidewalk are not straight, and the brick joints are too large.
1, phenomenon: (1) The longitudinal and transverse joints are staggered and obviously bent over 10mm.
(2) In the curved part, it is also laid according to the curve, forming a radial transverse joint with too wide outer side.
2, preventive measures: (1) cement concrete pavement, according to the road line type and design width, should make paving plan in advance, do a good job of technical disclosure, do a good job of measuring and setting out; In order to make the longitudinal and transverse joints straight, theodolite should be used to do a good job in the layout of longitudinal baseline. According to the baseline, the dimensions between ribs should be accurate and the diagonal lines should be equal.
(2) The paving method of the whole section of the unit project should be implemented according to a unified plan, and it is not possible to "go it alone".
(3) The curved part should also be straightened and then trimmed.
Five, masonry mortar is not full
(1) Phenomenon: Mainly manifested in the masonry of mortar blocks and flaky, with gaps and holes between blocks and flaky.
(2) Treatment method: Mortar blocks and flaky should be built with mortar, gaps between vertical joints and stones should be filled with mortar, and stones should be completely wrapped with dense mortar. At the same time, mortar should have
A certain consistency (3-5 cm measured by a consistency meter) is convenient for cementation with the stone surface. Dry grouting is strictly prohibited.
Six, masonry flatness is poor, there are joints.
(1) phenomenon: the exposed surface of masonry is uneven, which exceeds the requirements of flatness standard. There are more than two layers of through seams.
(2) Treatment method: A, pay attention to the choice of stone with a plane on one side. The minimum side length of flaky center thickness should not be less than 15cm, and the width of stone should not be less than 20cm to ensure the stability of masonry.
B, should be Ding Shun and pressure joint masonry, a layer of Shi Ding, a layer of stone, at least two along the Yi Ding. Shi Ding should be greater than 1.5 times that of the stone, and the staggered joints of the upper and lower layers should be not less than 8cm.
C, masonry height shall not be greater than1.2m.
D, measuring unreeling personnel, should always check the accuracy of the masonry surface (elevation, slope, distorted surface) line.
Seven, vertical stone foundation and vertical stone back support
1. phenomenon: the foundation is not firm, the stone back support along the vertical edge is backfilled with waste, and the virtual soil is not compacted or the compaction fails to reach the required density, which will deform, sink and bend after it is completed and put into use.
2. Treatment method: a. The longitudinal kerb foundation shall be paved with the same structure as the pavement base and rolled synchronously; Overexcavation at the bottom of the trough should be compacted.
B, according to the design requirements, arrange along the stone, mortar undercover, and tamp along the stone to make it dense at the grass-roots level.
C, along the stone back support according to the design and specification requirements.
D, along the vertical stone volume is slightly larger, along the vertical stone length is longer, easy to build by laying bricks or stones, straight.
Eight, tree set stone sinking
1. phenomenon: the tree sleeve stone sinks and tilts after installation, and it is loosely connected with the surrounding track plate, and the gap is too large.
2. Treatment method: The tree stone foundation should be laid in the same structure as the sidewalk base, and rolled synchronously; Before paving the road, make the tree pool template according to the design scheme, and determine the pavement scheme around the tree pool in advance.
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A little experience, I hope it will help you.