The Roadbed Stability And Anti Frost-Heaving And Thaw-Settlement

The phenomenon of Frost heave and Melt down
Analysis of the causes of high railway foundation settlement:
Taking the subgrade settlement of Wuqing station in Beijing-Tianjin intercity high-speed railway as an example. If there is a flood caused by heavy rain, the bridge part is prone to settlement. The settlement near Wuqing station of the intercity high-speed railway is like this way.

Frost heave
Due to the presence of negative temperature, the moisture begins to collect from the lower layer to the frozen surface, forming ice crystals and an ice layer, resulting in frost heave, uneven road surface, deformation of the roadbed or cracks. (see Figure 1)

 

Melt down

The frozen soil core is an impermeable layer, which prevents the water in the upper part of the melted soil from being discharged, thereby causing the pulp to be poured.(see Figure 2).

The frost heave causes the various parts of the subgrade to be lifted or sunk, resulting in uneven deformation. Once this uneven deformation exceeds the allowable value, the subgrade will be severely damaged.

VANS TECH new material developed by our company and the filler are synthetically solidified to form a solid large-scale integral roadbed. If it is applied to the high-speed rail and general railway foundation, it can construct a large-scale subgrade of tens or hundreds of kilometers, which can effectively prevent the subgrade’s melting, frost heaving, frozen soil and damage, and ensure the smooth and safe operation of the railway locomotive. Greatly reduce the cost of maintenance and repair work.

 

Practical application case

We repairs the track subgrade of:
1.Tianjin South Railway Station,
2.Beijing-Qinhuangdao Railway,
3.Beijing-Shanghai Railway,
4.Beijing-Guangzhou Railway,
5. The track plate of Anyang Station,
6.The bridge in the Wuhai Works Section of the Inner Mongolia Railway Bureau.All above cases proved its excellent performance under high and low temperature resistance, high speed impact resistance and strong vibration resistance after more than 5 years of use.

National test center test room test data

Soil solidified sample test data
Items Weight

(g)

Compressive strength (MPa) Flexural strength

(MPa)

Remarks
1 401 26.6 >12.7 GB/T2567-2008, Samples size: 40*40*160mm, 7 days Continuous test results
2 375.3 22.4 >12.1
3 387.5 25.2 >12.4
4 387.9 24.73 >12.4 Average value
5 Freeze-thaw test for 500 times by cycling. Cycling test: Stay in hot water for 4 hours by 35℃, and then Stay in freezer for 4 hours by -35℃ .

 

TEST REPORT
Producer BEIJING VANS TECH CO., LTD.
Samples 1kg*7groups
Test conditions The temperature 23℃,The relative humidity 45%
TEST VALUE
Items Test content Actual test value
1 Compressive strength (MPa) 3 days 22.78
2 Compressive strength (MPa) 3 days 24.73
3 Flexural strength (MPa) 3 days 12.4
4 Freezing and thawing test

( 500 times by cycling )

No bubbles

No shedding

No expansion

No shrinkage

■ ■ Product characteristics:
● Can be made as a huge solidification; can improve the supporting force; can prevent the deformation of the roadbed, and basically can eliminate the frost-heaving and thaw-settlement;
● It does not change, expand, or shrink in the range of -40°C to 110°C;
● It is excellent in water resistance, corrosion resistance, and impermeability;
● It has excellent bending resistance, elasticity, strong crack and shock resistance; It can absorb the vibration and reduce the noise.
● It can effectively prevent chemical corrosion into the roadbed solidified body.
● Micro-expansion during expansion (about 1-2% expansion), which increases the density and strength of the solidified body. There is no expansion and no shrinkage for finished items.
● It has strong weather and aging resistance, no powdering, and can withstand seawater erosion and soaking.
● Environmentally friendly. No VOC, moisture-proof, leak-proof, mildewproof, non-toxic and non-polluting.
● The operation is safe and convenient, the operation period is short, and it can be applied on wet and dry base.
■ ■ The applications:
Solid soil, solid stone, and solid sand, which contains the consolidation of unstable roadbeds including railway subgrades, frozen soil roadbeds, and highways.

                                TEST REPORT                      page1
Producer BEIJING VANS TECH CO., LTD.
Samples 1kg*7groups
Test conditions The temperature 23℃,The relative humidity 45%
TEST VALUE
Items Test contents Standard Value Actual test value Result
1 Gel setting time, min ≤120 90 GOOD
2 Bond strength, MPa ≥0.5 1.38 GOOD
3 Viscosity, Pa.s ≤1 0.0645 GOOD
4 Shear strength Mpa, 2h ≥0.5 2.14 GOOD
5 Shear strength Mpa, 24h ≥1 3.27 GOOD
6 Shear strength Mpa, 7 days ≥2 3.96 GOOD
7 Tensile Strength

Mpa, @-10℃

—- 7.71 GOOD
8 Elongation at break

%, @-10℃

—- 244 GOOD
9 Tensile Strength

Mpa, @-30℃

—- 10.36 GOOD
10 Elongation at break

%, @-30℃

—- 337 GOOD

 

                              TEST REPORT                        page2
Producer BEIJING VANS TECH CO., LTD.
Samples 1kg*7groups
Test conditions The temperature 23℃,The relative humidity 45%
TEST VALUE
Items Test contents Standard Value Actual test value Result
11 10% HNO3 resistant, 30 days No bubbles

No shedding

No expansion

No shrinkage

No bubbles

No shedding

No expansion

No shrinkage

GOOD
12 20% HCI resistant, 30 days GOOD
13 20% H2SO4 resistant, 30 days GOOD
14 10%NaOHresistant, 30 days GOOD
15 Shrinkage, % 7 days ≤1 <1 GOOD