CLC classification number: TB 332: A FRP sand pipe is mainly composed of glass fiber with high tensile strength, pressure-resistant and wear-resistant quartz sand and resin. This sandwich winding structure not only exerts the high strength of winding glass fiber reinforced plastic, but also effectively improves the moment of inertia of the cross section, thereby improving the structural rigidity. Since the advent of the FRP sand pipeline in the United States in the mid-1960s, it has a history of more than 30 years. The application in conveying water and other liquids is more and more extensive, showing strong market competitiveness and entering a new high-speed long-term. For the glass fiber reinforced plastic sand pipeline buried underground, due to its complicated loading conditions, the structure size of the pipe changes greatly under different use conditions and installation conditions, so it is designed to simulate the actual application conditions and according to the FRP structural design theory And engineering control standards, calculate and list the wall thickness of pipes with a nominal diameter of 2004000mm for engineering design and application. 1 Design of buried FRP sand pipeline process design The pipeline adopts the fixed-length winding method, uses the microcomputer to control the sanding winding machine, according to a certain winding rule, automatic winding forming, solidification at normal temperature and pressure and lining, winding, trimming, The raw materials and auxiliary materials used for forming the assembly line in various processes such as demolding are as follows: (1) Matrix materials: isophthalic UP resin, Palatal A400 ~ 952, initiator, methyl ethyl ketone peroxide; accelerator, cobalt naphthenate (2 strong materials: Surface felt, 30 ~ 60g / m2; chopped felt, 300 ~ 600g / m2; mesh cloth, fiber mass fraction 45% ~ 65%; no shouting ~ 30%; winding speed, 2 buried FRP sand pipe structure The cross section of the fiber-wound FRP sand pipe is divided into 5 levels, and each layer has its own function. 1. Inner lining: surface felt + chopped felt (anti-corrosion, anti-seepage); 2 inner winding layer: hoop + spiral fiber (Inner strong layer); 3. Sand layer: quartz sand (stiffness layer); 4. Outer winding layer: hoop + spiral fiber (outer strong layer); 5. Outer surface layer: resin-rich layer (anti-corrosion, anti-aging layer) 3 Mechanical analysis of buried FRP sand-laminated pipelines 3.1 Basic design conditions / m2, ④ 4000mm vehicle load; The soil condition of the original soil material at the laying depth of the pipe area: GC clay gravel, backfill soil soil condition: SG medium compacted soil; ⑨ pipe stiffness grade: SV = 3.2 Load analysis and calculation The load on the underground buried pipe is generally as follows: The weight of the pipe, the weight of the fluid in the pipe, the static pressure of the fluid in the pipe, the fluctuating pressure caused by the sudden increase or decrease in pressure due to the change in the flow rate of the fluid in the pipe, the external pressure caused by the weight of the backfill, the wheel pressure of the vehicle, or the ground stacking load Temperature difference load, the force caused by uneven settlement of the foundation due to construction excavation, the force received by the pipe during lifting and transportation and installation, the longitudinal force generated by the fluid pressure in the pipe at the turning point of the pipe, and the vacuum negative pressure in the pipe Negative pressure and seismic force, etc. Briefly indicate the main external load on the pipeline under certain laying conditions 3.2.1 Buried FRP sand pipe Main load calculation The static earth pressure distribution around the pipe (as shown) can be considered to be placed in the pipe body The weight of the rectangular soil block above is the vertical soil load acting on the tube. The height of the soil block should be equal to the depth of coverage , The width is equal to the outer diameter of the tube by the Janssen formula, q = VH (V is the specific gravity of the backfill soil, H is the depth of the covering soil, and the horizontal soil pressure on the tube side is calculated, generally acting on the tube side in a symmetrical form, its formation mechanism is The vertical earth pressure causes the deformation and elongation of the pipe ring in the horizontal direction. This deformation is constrained by the soil filling on the side of the pipe, thereby forming the horizontal earth pressure on the pipe side. According to Sfangle theory, the horizontal static earth pressure is on the center of both sides of the pipe The angle U is parabolic, and its 100 * horizontal maximum earth pressure qH = eAx / 2F vertical static earth pressure at the top of the pipe, Pa; ah is the horizontal directional earth pressure, Pa; foot t is the basic support coefficient; e is the passive soil Resistance coefficient; is the tube's hoop elastic modulus, MPa; / is the moment of inertia of the tube section, m3; A is the average radius of the tube, m; T is half of the supporting angle of the effective reaction force. 0.061R4, the above formula is simplified as: = 5.31X104Pa3.2.2 Earth pressure caused by ground dynamic load The dynamic load of the ground is usually generated by the car while driving, and it also causes the dynamic earth pressure around the pipe, and its distribution is as shown. According to the JC / T838-1998 standard, calculate the live load acting on the pipe, assuming that on a road with 4 lanes, each lane is 3.7m wide, a truck with a wheel load of 80000N is driving in the middle of the road. The body may be perpendicular or parallel to the direction of travel of the truck. Calculate the active load on the pipeline. 000N; I / is the impact coefficient; and L2 are the parallel and vertical load widths respectively. M 3.3 Pipe stiffness control When performing stiffness analysis, there is no medium in the pipe and there is no internal pressure. Related, that is, the pipe is under earth pressure and ground dynamic and static loads. Considering the initial deformation of the pipe after filling and its long-term lag effect, in addition, there is a partial deformation of the pipe ring caused by the dynamic load of the ground, then the horizontal radial deformation of the pipe ring is: Plastic Umbrella,Hat Umbrella,Cap Umbrella,Telescopic Plastic Cover Umbrella SHAOXING TIANYU UMBRELLA INDUSTRY CO.LTD , https://www.tianyuumbrella.com