Pads Sinking into Soft Ground
Pads on jacks are designed to provide a stable interface between the lifting equipment and the ground. When used on soft or uneven surfaces, the pads may sink into the ground, compromising stability and safety.
1. Causes of Pads Sinking
Soft or Unstable Ground: Loose soil, sand, mud, or wet surfaces cannot adequately support the pad and load.
Inadequate Pad Size or Design: Small or thin pads concentrate pressure on a small area, increasing the risk of sinking.
Excessive Load: Lifting loads beyond the pad’s rated capacity increases ground pressure, causing subsidence.
Environmental Conditions: Rain, snow, or thawed soil can reduce ground bearing capacity temporarily.
Repeated Use in the Same Spot: Continuous loading on the same area can gradually compress and sink the ground beneath the pad.
2. Effects of Pads Sinking
Loss of Stability: Sinking pads create uneven load distribution, increasing the risk of jack tilting or load slipping.
Increased Wear and Deformation: Pads may deform more quickly due to uneven stress and friction.
Operational Hazards: Sinking pads can cause sudden shifts in load position, posing safety hazards to personnel.
Potential Equipment Damage: Uneven stress can damage both the jack and the pad over time.
3. Preventive Measures
Use Larger or Reinforced Pads: Pads with larger surface areas distribute the load more evenly, reducing ground pressure.
Ground Stabilization: Place a solid base such as wooden planks, metal plates, or rubber mats under the pads on soft ground.
Avoid Overloading: Operate within the rated load limits to prevent excessive ground pressure.
Regular Inspection: Check pad condition and ground stability before lifting operations.
Environmental Awareness: Avoid using jacks on saturated, thawing, or otherwise unstable ground.
4. Conclusion
Pads sinking into soft ground is caused by unstable surfaces, inadequate pad size, excessive loads, and environmental factors. Using larger or reinforced pads, stabilizing the ground, and operating within rated loads are key measures to maintain safety and prevent equipment damage.
References
Gent, A. N. Engineering with Rubber: How to Design Rubber Components. Hanser Publishers, 2012.
Lake, G. J. “Fatigue and Fracture of Elastomers.” Rubber Chemistry and Technology, 2000.
ASTM D2240 – Standard Test Method for Rubber Property—Durometer Hardness.
ISO 2230 – Rubber Products—Guidelines for Storage and Maintenance.
ASTM D2000 – Standard Classification System for Rubber Products in Automotive and Industrial Applications.
