When a wheel excavator operates on soft ground, the core cause of tire sinking is that the ground contact pressure exceeds the ground-bearing limit. Meanwhile, insufficient tire grip and continuous softening of the ground will exacerbate the risk of sinking. Prevention and control must follow the core logic of "reducing specific pressure, enhancing adhesion, stabilizing operation, and early protection", and a practical solution should be formulated from four dimensions: pre-operation preparation, on-site protection, operation specifications, and emergency response. The details are as follows:
Before operation, detect the softness of the ground through test driving or a probe rod to identify the thickness of mud and loose soil, as well as the location of the underground hard layer.
For areas with insufficient bearing capacity, lay steel plates, subgrade plates, gravel cushions, etc., in advance. High-strength alloy subgrade plates are preferred. The laying area must cover the entire ground contact range of the tires, with edges extending 20-30cm beyond the outer side of the tires. Ground contact pressure is reduced by increasing the ground contact area (pressure can be reduced by more than 40% after laying steel plates). For temporary operations, hay, branches, etc., can be laid to simply enhance the ground-bearing capacity.
Check tire pressure. For soft ground, appropriately reduce the tire pressure (10%-15% lower than the standard pressure) to increase the ground contact area through slight tire deformation. However, avoid excessively low pressure, which may cause tire bead separation.
Clean mud and gravel from the tire tread to ensure the tread is fully exposed and improve grip.
Remove unnecessary counterweights from the machine body to reduce the total weight of the equipment and lower the pressure on the ground.
Define fixed routes for excavation and movement to avoid frequent rolling over the same area, which would reduce ground compactness and further soften the ground.
Prioritize routes in areas with slightly higher terrain and relatively hard ground, and avoid low-lying waterlogged areas and humus accumulation areas. At the same time, reserve an emergency evacuation channel.
For wheel excavators operating on soft ground for a long time, widened tire covers and anti-slip chains (with anti-slip teeth) can be installed. Widened tire covers directly increase the ground contact width of the tires, and the toothed structure of anti-slip chains enhances the bite force on the ground to prevent tire slipping and sinking.
For some extreme working conditions, special wide-base tires can be replaced. Their ground contact area is 30%-50% larger than that of ordinary tires, with stronger adaptability.
During operation, deploy the hydraulic outriggers and support them on pre-laid base plates (the area of each outrigger base plate is not less than 0.5㎡). Transfer part of the machine body weight to the outriggers to reduce the load-bearing pressure on the tires.
The outriggers must bear force evenly to avoid machine body tilting caused by suspended outriggers on one side, which would otherwise exacerbate tire sinking.
Use low gear throughout movement, supply fuel at a constant speed, and strictly prohibit sudden acceleration, sudden braking, and high-speed turning. Sudden acceleration causes tire idling and damages the ground structure; high-speed turning generates lateral force that squeezes the soft ground—both are likely to cause sinking.
When steering, adopt small-angle segmented steering to avoid tires rolling over the ground laterally.
Keep the machine body horizontal during excavation to ensure even force on the four tires and avoid excessive load on tires on one side.
Follow the principle of "digging from far to near and in layers". Do not dig deeply at close range directly below the tires to prevent the machine body from sinking due to the reaction force when the bucket is unloaded.
Do not overfill the bucket to reduce the impact of the equipment's instantaneous weight on the ground.
Do not stay stationary at the same position for a long time during operation. Fine-tune the equipment position every 15-20 minutes to prevent ground settlement caused by long-term tire pressure on the same area.
During excavation, if slight tire sinking is detected, immediately move the equipment to a solid area to avoid worsening sinking.
When slight tire sinking is detected (the tire is not submerged beyond its radius), stop operation immediately. Lower the bucket to the ground to support the machine body, slowly lift the tire on the sinking side, then lay hard objects such as steel plates and gravel under the tire to form a support surface. Slowly retract the bucket to let the tire land steadily on the support, and drive out of the sinking area slowly.
If the tire sinks deeply, call equipment such as loaders and trailers for traction. Use a dedicated traction rope and fix it to the designated traction point of the machine body. Keep the traction speed slow and uniform to avoid damaging the chassis or tires.
At the same time, use the bucket to clean the loose soil around the tires to reduce traction resistance.
When the machine body sinks significantly, first lay a large area of steel plates or subgrade plates in front of and below the tires to build a temporary channel. Then perform coordinated operations with bucket auxiliary support and external traction.
Forcibly stepping on the accelerator is strictly prohibited, as this will cause the tires to sink deeper and even damage the hydraulic system.
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