Let me tell you about the service life and acceptance standards of manhole covers:
Cement manhole covers are widely used in our daily lives. They are one of the common objects on our roads. Their widespread use has greatly improved the recycling and utilization of unusable resources. What are the factors that affect the service life of cement manhole covers? Let me briefly introduce the service life of cement manhole covers.
The effect of powder performance on the compaction of cement manhole covers The compaction performance of powders with high hardness, low plasticity, and high friction is poor, and can be appropriately improved by adding lubricants or forming agents. When the purity of the powder is low and the oxygen content is high, the compaction performance is poor, which can be overcome by reducing the original powder. Single fine or coarse powder, as well as conventional powder, have unsatisfactory compaction performance. Mixed powder and powder with complex particle shapes can improve compaction performance.
The influence during the process of pressing cement manhole covers; The smoother the surface of the formed cement manhole cover, the higher the hardness and rigidity, which is more conducive to the improvement of poor bulk density and uniformity; The density of the green body pressed in two directions is higher and more uniform than that of the green body pressed in one direction. The lower the pressing speed, the longer the insulation time, which is beneficial for improving the density of the billet, especially for large or complex shaped grinding tools.
The influence of foundation shape: When calculating the bearing capacity of the foundation using the load theory formula, it is considered as a strip foundation. For non strip foundations, the influence of different shapes on the bearing capacity of the foundation should be considered. The influence of load inclination and eccentricity: When calculating the foundation bearing capacity using theoretical formulas, it is considered based on the load, but the inclination and eccentricity of the load have an impact on the foundation bearing capacity.
The impact of the shear strength of the covering layer: The higher the shear strength of the covering layer above the basement, the significantly higher the bearing capacity of the foundation. Therefore, the excavation size and construction backfill quality of the foundation pit have an impact on the bearing capacity of the foundation; The impact of the underlying layer: Determine the design value of the bearing capacity of the foundation bearing layer, and conduct specific analysis and verification of the impact of the underlying layer; In addition, there are also the effects of foundation inclination and ground inclination: the compressibility of the foundation soil and the ratio of the test layer to the actual foundation size. The influence of adjacent foundations, load rates, and the interaction between the foundation and the superstructure.
Inspection standards for cement manhole covers:
Cement manhole covers are common objects in our daily lives and have been widely used on roads. Although we do not pay attention to this object in our daily lives, there is a lot of knowledge we need to learn about this manhole cover. Below, I will briefly introduce the inspection standards for cement manhole covers, which are for your reference only:
The burial depth of the manhole cover. Heavy manhole covers should not be less than 40mm, and light manhole covers should not be less than 30mm.
The protrusion height on the surface of the manhole cover should not be less than 3 millimeters.
The surface of the manhole cover and bracket should be cast flat and smooth. There should be no cracks, cold shuts, shrinkage and other defects that affect the performance of the manhole cover. Repair welding is not allowed. The assembly structure dimensions of the manhole cover and bracket should comply with the requirements of GB6414, and the tolerance level should not be lower than GB6414-86 CT10. Ensure the interchangeability of the manhole cover and bracket.
The contact surface between the manhole cover and the bearing should be machined to ensure smooth contact between the manhole cover and the bearing.