② Reduce foundation settlement. The compression of foundation bearing layer accounts for a large proportion in the total settlement. Due to the low compressibility of cushion material, the total settlement will be greatly reduced after setting cushion. In addition, due to the stress diffusion of the cushion, the pressure transmitted to the underlying layer under the cushion is reduced, which will also reduce the compression of the underlying layer.
③ Adjust the uneven settlement of foundation. In the design of cushion, unequal thickness cushion is sometimes used to adjust the differential settlement of foundation according to the characteristics of upper load. In addition, uneven hardness of rock and soil is often encountered in mountain foundation. At this time, the exposed rock at the basement can be chiseled to a certain thickness, and then the compressible sand or plain soil can be backfilled and compacted in layers to adapt to the deformation of the highly compressible soil foundation.
(4) accelerate the foundation drainage consolidation. Sand and gravel cushion has high water permeability, which can become the drainage surface of saturated soft soil, making the pore water pressure on the upper part of soft soil easy to dissipate, thus accelerating the consolidation of soft soil and improving the shear strength of soft soil. In addition, sand and gravel cushion can prevent frost heave and eliminate the expansion and contraction of expansive soil foundation. In seasonal frozen soil areas, sand generally does not frost heave; Replacing expansive soil with sand cushion can effectively avoid the expansion and contraction of soil.
Extended data
The square of concrete pavement belongs to pavement, and the calculation method of pavement is as follows:
1. The quantities of asphalt concrete, cement concrete and other pavements in road engineering are calculated by multiplying the design length by the actual paving area of widened parts such as design width and circular arc, and the area occupied by various wells in 1.5_ is not deducted. ?
2. The expansion joint is calculated by area according to the design expansion joint length × expansion joint depth, and the sawing machine is calculated by length in meters. ?
3. The pavement surface layer shall be calculated in square meters according to the area shown in the design drawings (the surface layer with flat stones shall be deducted from the flat stone area).
Matters needing attention in road area calculation:
1. The shaping and rolling of the road bed groove shall be calculated according to the size shown in the design, and the area of the road bed groove shall not be deducted. The width of subgrade groove shaping and rolling is calculated according to the designed road width. Pavement shaping and rolling shall be calculated in terms of sidewalk area according to the design graphic size, and the kerb area connected with the roadway shall be deducted.
Second, all kinds of roadbed are calculated by multiplying the length and width of the roadway with the design graphic size by the area, without deducting the area occupied by all kinds of wells, and the width of roadbed is calculated by the widening value on both sides of the design roadway width. ?
Three, multi-element composite soil health according to the design graphic size to the top of the base area, without deducting the area of various wells. ?
Four, cement concrete pavement * * * vibrating macadam base is calculated according to the design top surface area.
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