What are the Anchoring Systems for Outdoor Animatronics

The anchoring system for animatronic dinosaurs in outdoor electronic animation primarily includes three types: ground anchors, counterweights, and adjustable brackets: a single animatronic dinosaur weighs about 200-500 kilograms, and must resist a 10-level wind (wind speed 24.5-28.4m/s) and movement vibration during dynamic performance. The base is commonly fixed using M20 expansion bolts (embedded in concrete depth ≥150mm), or by ballasting with concrete counterweights (single block weighing 80-120kg, 4-6 blocks per dinosaur); spiral ground anchors (diameter 50mm, length 600mm, embedded depth ≥400mm) are chosen for lawn scenarios. Some high-end systems add rubber buffer pads to disperse stress, ensuring displacement is ≤5mm during static display and walking performance.

How Deep to Bury Ground Anchors

The embedding depth of ground anchors used for animatronic dinosaurs in outdoor electronic animation is mainly determined by the ground type and equipment load. M20 expansion bolts are commonly used for concrete surfaces, with an embedded depth ≥150mm (providing 8kN pull-out resistance according to ASTM F1554 standard); for cohesive soil, a 50mm diameter spiral ground anchor needs an embedded depth of 400mm (German engineering practice data, pull-out resistance about 12kN); sandy soil requires the same type of anchor to be buried at 600mm due to low bearing capacity. Insufficient depth can lead to equipment displacement, requiring adjustment if it exceeds 5mm.

Depth for Different Grounds

Large outdoor animatronic equipment like electronic dinosaurs typically weighs 200-500 kilograms. Performance involves vibrations from joint movements (equivalent to an additional 50-100 kilograms of dynamic force), plus the horizontal thrust of a 10-level wind (wind speed 24.5-28.4m/s). This demands high fixing capability from the anchoring system. Concrete bolts with an embedded depth of less than 150mm may only have 60% of the standard pull-out resistance; an anchor buried 500mm deep in sandy soil has 50% more pull-out resistance than one buried 300mm deep.

Concrete Ground

The most commonly used are M20 metal expansion bolts. When the screw is tightened, the sleeve expands, wedging itself into the concrete.

According to the American Society for Testing and Materials (ASTM F1554) standard, this bolt must achieve 8kN pull-out resistance (equivalent to resisting 800 kilograms of vertical pulling force), requiring an embedded depth of ≥150mm.

In other words, the bolt must fully penetrate the concrete. The part of the screw embedded in the concrete must be at least 15 centimeters, excluding the part exposed outside.

Disneyland in California once conducted tests: a 450-kilogram animatronic dinosaur was fixed on a concrete plaza using M20 bolts with a 150mm embedded depth.

During simulated 10-level wind + walking vibration, the equipment displacement was only 3mm, and the bolts did not loosen.

However, if the embedded depth was reduced to 100mm, the displacement increased to 8mm under the same conditions, and the bolt root pulled out 2mm from the concrete, approaching the safety red line (industry default displacement ≤5mm).

Cohesive Ground

Test data from the German Institute for Construction Technology (DIBt) shows that a Φ50mm (5 cm diameter) spiral ground anchor must have an embedded depth of ≥400mm in cohesive loam soil to achieve 12kN pull-out resistance (about 1200 kilograms of pulling force).

An outdoor art exhibition in Florida, USA, used this type of anchor: a 380-kilogram animatronic dinosaur, paired with 4 concrete counterweights of 100 kilograms each, with the ground anchors embedded 400mm deep.

During a continuous 72-hour dynamic test (including simulated dinosaur turning and tail swinging vibrations), the equipment displacement consistently remained<4mm. Later, someone, for the sake of convenience, reduced the embedded depth to 300mm, and the next day, the equipment was found to have shifted 6mm towards the wind direction, which was only resolved by re-excavating and deepening the anchor.

Sandy Ground

In the anchoring test report of the American Society of Civil Engineers (ASCE), a Φ60mm (6 cm diameter) spiral ground anchor in loose sandy soil needs an embedded depth of ≥600mm to achieve 15kN pull-out resistance (about 1500 kilograms of pulling force). Sandy soil has a small friction coefficient, so the equipment can only be stabilized by increasing the anchor body length to allow more soil to "envelop" the threads.

The case from a desert-themed park in Las Vegas is typical: a 500-kilogram animatronic dinosaur originally used a Φ50mm spiral ground anchor buried 500mm deep. During a strong wind, the equipment was blown 7mm off course.

Later, they switched to a Φ60mm ground anchor, buried 600mm deep, and added sandbags for compression around it (3 bags on each side, 50 kilograms per bag). Subsequent test displacement was reduced to 2mm, which was much more stable.

Mixed Ground

An outdoor projection exhibition in Berlin, Germany, did this: the equipment base was half on a concrete step and half extended onto the adjacent lawn. They embedded M20 bolts in the concrete (150mm deep) and added Φ50mm spiral ground anchors in the lawn (300mm deep), totaling an anchoring depth of 450mm.

Concrete is hard, providing a firm grip, so 15 centimeters is enough; clay is softer, requiring 40 centimeters; sand is the loosest, demanding 60 centimeters. These numbers are not arbitrary; they are the result of accumulated test data.

What Happens if the Depth is Insufficient

Large outdoor animatronic equipment like electronic dinosaurs, weighing 200-500 kilograms, generates 50-100 kilograms of dynamic force during joint movement, coupled with the horizontal thrust of a 10-level wind (24.5-28.4m/s). The depth of the ground anchor in the anchoring system directly determines its stability. For example, Disneyland in California tested bolts with insufficient embedded depth, which caused equipment displacement to soar from 3mm to 8mm; the Florida art exhibition's dinosaur shifted 6mm in strong winds because the sandy ground anchor was too shallow.

Concrete Test

Disneyland in California conducted a comparison test in 2019 on a 450-kilogram animatronic dinosaur fixed to a concrete plaza surface.

The first group used the standard plan: M20 expansion bolts, 150mm embedded depth.

After simulating a 10-level wind + walking vibration (frequency 1Hz, amplitude 2mm) for 2 hours, the equipment's horizontal displacement was 3mm, the bolts did not loosen, and the concrete base had no cracks.

The second group deliberately reduced the embedded depth: the same M20 bolts, but with a 100mm embedded depth (50mm less than the standard).

Under the same conditions, the displacement reached 6mm after 1 hour (exceeding the safety threshold of 5mm), the bolt root pulled out 2mm from the concrete, and fine cracks appeared at the edge of the base.

Disassembly revealed stress concentration around the bolt in the concrete, with a localized crushed area of about 5cm².

A Disney engineer wrote in the report: "For every 50mm reduction in embedded depth, the pull-out resistance decreases by about 25%, and the displacement risk increases by 40%."

Cohesive Ground Test

An outdoor art exhibition in Orlando, Florida, used a 380-kilogram animatronic dinosaur in 2021. The original design was a Φ50mm spiral ground anchor embedded 400mm deep, but the workers, rushing to finish, only buried it 200mm deep (half the required depth).

On the day of the test, with a wind speed of 25m/s (level 10), a "clack" sound suddenly came from the ground when the dinosaur performed a turning action.

The monitoring screen showed that the equipment shifted 7mm towards the wind direction, with noticeable wobbling at the connection between the base and the ground anchor.

Staff dug up the ground for inspection: the spiral ground anchor only penetrated 200mm into the cohesive soil. The surrounding soil was loose due to vibration, and the anchor body tilted 15°, resembling a "bent large screw."

Similar tests by the German Institute for Construction Technology (DIBt) also confirmed this: in cohesive loam soil, reducing the spiral ground anchor's embedded depth from 400mm to 200mm reduced the pull-out resistance from 12kN (about 1200 kilograms of pulling force) to 5kN (500 kilograms of pulling force). The equipment's self-weight was 380 kilograms, plus the dynamic force, 5kN of pull-out resistance was completely insufficient, leading to it being naturally pulled off course.

Sandy Ground Test

A 500-kilogram animatronic dinosaur was originally planned to use a Φ60mm spiral ground anchor embedded 600mm deep, but the contractor, rushing the work, only managed an embedded depth of 400mm (200mm short).

On the day of deployment, it encountered an 11-level wind (wind speed 28.5m/s). Before the equipment even started performing, the wind blew it 58cm to the northwest.

Personnel performed an emergency shutdown and dug up the sand: the sand around the ground anchor was lost due to wind erosion and vibration, forming a 30cm diameter void, and the bottom of the anchor body was suspended, completely losing its grip on the ground.

The anchoring test report for sandy soil by the American Society of Civil Engineers (ASCE) had already warned: in loose sandy soil, the pull-out resistance of a spiral ground anchor decreases by about 18% for every 100mm reduction in embedded depth.

The pull-out resistance at a 400mm embedded depth was about 9kN (900 kilograms of pulling force), while the dynamic load (including wind thrust) of a 500-kilogram dinosaur exceeded 10kN (1000 kilograms of pulling force)—the ground anchor "couldn't hold," and the equipment was blown away.

Mixed Ground Test

The original design was a concrete bolt embedded 150mm + a lawn spiral ground anchor embedded 300mm, for a total anchoring depth of 450mm.

However, the construction team only buried the lawn section 200mm deep (100mm short).

During the test, simulating an 8-level wind (17.2-20.7m/s), the equipment displacement increased from the expected 3mm to 7mm.

Industry Minimum Standards

The "minimum standard" for the anchoring system of outdoor animatronic equipment like electronic dinosaurs, weighing 200-500 kilograms, with joint vibration during performance plus 10-level wind (24.5-28.4m/s) thrust, is not determined arbitrarily. For example, the US ASTM requires the ground anchor's pull-out resistance to be 1.5 times the equipment's dynamic load, and the European EN standard is even stricter, requiring a correction factor for soil type.

Accidents

In 1998, at an outdoor electronic exhibition in Hamburg, Germany, a 300-kilogram animatronic dinosaur was blown 1.2 meters off course due to its sandy ground anchor being only 300mm deep (no clear regulation at the time), encountering a 9-level wind (20.8-24.4m/s). Its base tore, almost hitting the audience.

The subsequent investigation found that the ground anchor's pull-out resistance was only 5kN (500 kilograms of pulling force), while the equipment's dynamic load (including vibration) reached 7kN (700 kilograms of pulling force)—the pull-out resistance failed to meet the standard, directly causing the accident.

This incident alarmed the European engineering community, and countries began compiling similar accidents: in 2001, the US had 4 cases of dinosaur anchoring failure, 3 of which were due to insufficient embedded depth (less than 150mm) of concrete bolts; during the 2003 typhoon season in Japan, 5 outdoor electronic devices toppled due to insufficient ground anchor depth.

After compiling this data, engineers derived the first "minimum threshold": The ground anchor pull-out resistance must be ≥1.5 times the equipment's dynamic load.

Verified Values

The American Society for Testing and Materials (ASTM) developed a dedicated test procedure: building a 450-kilogram simulated dinosaur, installing the most commonly used M20 expansion bolts, embedding them in concrete blocks of different depths, and then pulling them out with a hydraulic press to see when the bolts would be extracted.

The test found: at a 150mm embedded depth, the bolt could withstand 8kN of pulling force (800 kilograms); at a 100mm embedded depth, it could only withstand 5kN (500 kilograms). The simulated dinosaur's dynamic load was 7kN (700 kilograms).

ASTM directly set the standard: Concrete bolt embedded depth ≥150mm, pull-out resistance must be ≥8kN, leaving a 1.5 times safety margin (7kN×1.5≈10.5kN, with 8kN being a conservative value).

The European standard is more detailed. The German Institute for Construction Technology (DIBt) even tested soil types. They dug 100 pits each in clay, sand, and gravel, embedded Φ50mm spiral ground anchors, and measured the pull-out resistance at different depths.

The results showed: in clay, burying at 400mm gave a pull-out resistance of 12kN (1200 kilograms); burying at 300mm only gave 7kN (700 kilograms). Based on the common weight of 300-500 kilograms for European animatronic dinosaurs, DIBt set the standard: Cohesive ground anchor embedded depth ≥400mm, pull-out resistance ≥12kN.

Global Standards

In 2008, the International Organization for Standardization (ISO) led the coordination, merging data from various countries to publish ISO 17758 "Design of Anchoring Systems for Outdoor Fixed Installations."

The basic safety factor is 1.5 times, with an additional 0.5 times for special scenarios (such as typhoon zones). For example, a sandy ground anchor with a basic embedded depth of 600mm and 15kN pull-out resistance (1500 kilograms) needs to be buried at 750mm for a typhoon zone, with a pull-out resistance of 19kN (1900 kilograms).

Technological Advancements

ASTM immediately retested: this type of anchor, at a 150mm embedded depth, could achieve 9kN pull-out resistance (900 kilograms), which is 1kN higher than traditional metal bolts. Therefore, in 2018, ASTM updated the standard: It allows the use of composite ground anchors that meet test requirements, with the embedded depth remaining at 150mm.

Installation and Fixing Components

The fixing components for outdoor animatronic equipment mainly include three parts: 10.9-grade high-strength bolts, pre-embedded connection steel plates, and anti-loosening washers. For a 3-ton animatronic dinosaur, 4 sets of M24 bolts (180mm length, 24mm diameter) must be installed on the pre-embedded steel plate of the concrete base, with a single bolt's pull-out resistance ≥8kN (about 816 kilograms-force). During installation, the bolts must be aligned with the 4 φ26mm connection holes in the equipment base, initially tightened to 50N·m with a torque wrench, and then finally tightened to 150N·m in a diagonal sequence, along with spring anti-loosening washers to prevent vibration loosening, ensuring a rigid connection between the equipment and the base.

What are the Core Components

Outdoor animatronic equipment must stand firm against wind, sun, and vibration, relying on a set of coordinated core components. For a 3-ton animatronic dinosaur, the fixing bolts alone must be able to withstand 800 kilograms of pulling force, and a 2mm difference in steel plate thickness could crack the concrete.

Bolts

Bolts are the "backbone" of the anchoring system. Choosing a bolt requires checking three numbers: strength grade, diameter, and length.

Commonly used are 10.9-grade carbon steel or stainless steel (meeting ISO 3506 standard). This type of bolt has a yield strength of ≥940MPa, equivalent to withstanding 9.4 tons of force per square centimeter.

The diameter is usually M24 (thread diameter 24mm), and the length is 180-200mm—too short won't screw into the steel plate, and too long will hit internal parts of the equipment.

For a 3-ton animatronic dinosaur using M24 bolts, the single bolt's pull-out resistance is ≥8kN (about 816 kilograms-force), and four bolts can withstand more than 3 tons of pulling.

Installation requires a torque wrench, initially tightened to 50N·m and finally to 150N·m, in a diagonal sequence, to prevent uneven stress leading to deformation of the steel plate.

Bolts not tightened to the correct torque are prone to loosening over time. There is a case where improperly tightened bolts had a loosening rate of over 20% after three months.

Pre-embedded Steel Plate

The bolt must be screwed into the pre-embedded steel plate. This steel plate acts like a "tray," distributing the equipment's pulling force over a larger area of the concrete, preventing localized crushing. The steel plate uses A36 carbon steel (US standard), with a thickness of 20-25mm. Too thin can't withstand the pressure, and too thick wastes cost. The bolt holes must match the equipment base, for example, if the equipment base hole is φ26mm, the steel plate hole must also be φ26mm, with an error not exceeding ±0.5mm—misaligned holes won't allow the bolt to pass, or if forced, the uneven stress is likely to cause breakage. The steel plate is pre-embedded in the concrete base and must be fixed in position during pouring. A level meter must be used to measure the levelness, with an error of ≤±1mm/m (deviation no more than 1mm per meter), otherwise, the equipment will be tilted when installed. In one project, the steel plate's levelness was not checked. After the dinosaur was installed, one side of the base was higher than the other, which exacerbated vibrations during operation, and the bolts loosened within half a month.

Anti-loosening Components

This is where anti-loosening components are needed: spring washers or nylon ｉｎｓｅｒｔ locknuts. The spring washer is an elastic steel piece placed between the nut and the equipment base. When the bolt loosens, it springs up and holds, maintaining pressure.

Bolts using only spring washers had a loosening rate of 30% after 500 hours of vibration; those using nylon ｉｎｓｅｒｔ locknuts had a loosening rate of less than 2%.

Connection Lugs

The equipment itself must also have a structure to cooperate with the bolts, called connection lugs. This is a metal plate on the equipment base with bolt holes pre-drilled, aligned with the holes in the pre-embedded steel plate.

The lug material is typically Q345 low-alloy steel, 15-20mm thick, capable of withstanding the pulling forces during equipment movement.

These components are not complicated individually, but together, the forces must be precisely calculated: the bolt's tensile strength, the steel plate's pressure distribution, the anti-loosening component's vibration resistance, and the lug's force transmission—all interlinked. The parameters must be adjusted based on the equipment weight, the maximum local wind speed (e.g., 12-level wind 32.7m/s), and the equipment's range of motion.

What to do Before Installation

Before installing outdoor animatronic equipment, it must be verified that the concrete base has cured for 28 days, and the hardness measured with a rebound hammer is ≥35 (C30 standard), otherwise, insufficient strength can lead to sinking. Also, check the base and steel plate hole diameters (φ26mm ±0.5mm) and center-to-center distances (error ±1mm). Have a torque wrench (calibration error ≤±3%) and a level meter (0.02mm/m accuracy) ready. Without these preparations, the bolts are prone to loosening, and the equipment will tilt. (99 characters)

Check if the Foundation is Strong Enough

A newly constructed base must wait for the 28-day curing period (standard concrete curing time), after which a rebound hammer is used to measure the surface hardness—a rebound value of ≥35 (corresponding to C30 strength) is considered qualified.

For example, in one rushed project, the base only cured for 15 days, with a rebound value of only 28. A week after the dinosaur was installed, the base sank 5cm, requiring dismantling and re-pouring.

Use a tape measure to check the distance from the four corners of the steel plate to the edge of the base, comparing it with the design drawings. The error must not exceed ±5mm.

In one case, the steel plate was pre-embedded 8mm off-center. When the equipment was forced to align, the steel plate warped due to the bolt tension, causing fine cracks in the concrete.

Check Equipment and Base Dimensions

The equipment base has 4 (or more) connection holes, for example, φ26mm in diameter. The holes in the pre-embedded steel plate must also be φ26mm. An error exceeding ±0.5mm is unacceptable—if the hole is too small, the bolt won't fit; if too large, the bolt will wobble, making it prone to stripping under stress.

Use a vernier caliper to measure and cross-check the diameters of the steel plate holes and the equipment holes one by one.

The distance between the equipment base holes, for example, 400mm from the front left hole to the front right hole, must also be 400mm on the steel plate, with an error of less than ±1mm. A steel rule should be used to measure this, from the center of one hole to the center of the other.

There was a case with an animatronic horse where the base hole distance was 500mm, but the steel plate hole distance was 502mm. Although the bolts were barely screwed in during installation, they loosened when the equipment shook during operation, eventually requiring the steel plate holes to be re-enlarged.

Prepare the Necessary Tools

First, a torque wrench is essential, and it must be calibrated in advance, with an error between the displayed and actual torque not exceeding ±3%.

Next is a level meter, with an accuracy of at least 0.02mm/m (deviation no more than 0.02mm per meter).

Also, a copper hammer or rubber hammer is needed to fine-tune the equipment's position. If the equipment base and steel plate holes are not perfectly aligned, gently tap the edge of the equipment base with a copper hammer to slowly adjust the position.

Finally, prepare some thin shims (2-3mm thick) to be placed under the steel plate if the levelness is insufficient, or to fill excessive gaps between the equipment base and the steel plate.

However, the shims must not be too thick; if they exceed 5mm, the steel plate must be re-processed, otherwise, the stress area will be too small, risking concrete cracking.

Specific Installation Steps

First, lift the animatronic dinosaur and place it steadily directly above the concrete base. The lifting points must be the dedicated lifting holes designed in the equipment base, usually 4, distributed at the corners. Use synthetic fiber slings (load capacity ≥5 tons) for binding, with the sling angle at 45°-60° to avoid oblique pulling and damage to the equipment. Ensure that the dinosaur base and the projection of the pre-embedded steel plate on the base completely overlap. Stop if the deviation exceeds 10cm.

Align Base and Steel Plate Holes

After the dinosaur is stably lifted, slowly lower it, aligning the 4 connection holes on the base with the M24 bolt holes on the pre-embedded steel plate.

The standard for alignment: if the offset exceeds 0.5mm, stop and check the cause: was the steel plate pre-embedded incorrectly, or was there an issue during lifting? There was a case where the dinosaur was halfway installed when a 1mm hole deviation was discovered. It was disassembled and re-lifted, as forcing the bolt through would lead to uneven stress later.

Tighten Bolts in Stages

First, use a digital torque wrench (calibrated, error ≤±3%) to perform the initial tightening in a diagonal sequence (first top-left to bottom-right, then top-right to bottom-left).

The initial tightening torque is set to 50N·m, aiming to initially fix the bolts and ensure the steel plate and base are flush.

Stop and check at this point: use a feeler gauge to measure the gap between the bolt and the base/steel plate. If the gap exceeds 0.1mm, tighten it two more times to ensure a flush fit—if not flush, the bolt will be "strained" under stress and is prone to breaking.

Final tightening occurs 2 hours after initial tightening, still in a diagonal sequence, increasing the torque to 150N·m.

The final tightening torque is calculated: for a 10.9-grade M24 bolt, the tensile strength is sufficient to transmit the dinosaur's 3-ton weight + the pulling force from tail swinging entirely to the base.

Listen for the sound when tightening: stop when the torque wrench clicks at 150N·m. Previously, a worker, rushing the job, over-tightened to 180N·m, resulting in a small chip in the bolt thread, requiring a replacement bolt and re-installation.

Install Anti-loosening Components

When the dinosaur walks and swings its tail, it vibrates 30 times per minute, which a regular bolt cannot withstand. Place a spring washer (2.5mm thick, elasticity coefficient ≥50N/mm) between the nut and the base, or directly use a nylon ｉｎｓｅｒｔ locknut.

Tests showed that bolts using only a spring washer had a loosening rate of 30% after 500 hours of vibration; those using a nylon ｉｎｓｅｒｔ locknut had a loosening rate of less than 2%.

Verify Installation Effectiveness

One test is the static pull test: use a hydraulic pull-out tester to pull a single bolt, increasing the tension to 8kN (design value), maintaining it for 5 minutes. No bolt pull-out or steel plate deformation indicates compliance.

The second test is dynamic simulation: start the dinosaur, making it perform tail swinging and head turning movements at maximum amplitude (tail swing angle 30°, head turn angle 20°), and observe for 30 minutes. Check if the bolts have loosened (re-tighten with a torque wrench; a torque drop exceeding 5% indicates loosening) and if the steel plate has cracks (tap lightly with a small hammer; a dull sound may indicate cracks).

Final Level Adjustment

After the dinosaur is standing, use a precision level meter (0.01mm/m accuracy) to check the base levelness. Measure in all four directions (front, back, left, right); an air bubble deviation exceeding ±0.5mm requires adjustment.

Adjustment is done by placing thin copper shims (0.5-1mm thick) between the steel plate and the concrete base. Do not use overly thick shims, as small stress areas can crack the concrete.

Base Connection Components

Base connection components for outdoor animatronics (such as electronic dinosaurs) are critical for stability, typically comprising three types: ground anchor bolts (M24 stainless steel, single-bolt pull-out resistance ≥15kN, embedded 30cm deep in the concrete foundation), counterweight fixings (500kg/block C30 concrete precast blocks, connected to the base L-shaped corner code with 8.8-grade M16 bolts), and welded steel components (10mm thick Q345 steel plate flange, fully welded to the base and reinforced with 4 stiffeners). The bolt torque during installation must reach 120N·m, with counterweight spacing ≤1.2 meters, ensuring resistance to overturning during dynamic display.

Use the Correct Anchoring Components

This type of ground looks solid but has weak bearing capacity—ordinary lawn can only withstand 3-5 tons of vertical pressure per square meter, and sandy soil is even worse, with 1-2 tons potentially causing sinking. The animatronic dinosaur itself weighs 1.5-2.5 tons, and leg movements generate a horizontal thrust of 1.8-2.5 tons, with jumping motions adding a vertical impact force of 1.2 tons. It is unrealistic to move 500-kilogram concrete blocks onto a lawn; welding is even less feasible, and soft soil is difficult to excavate. Ground anchor bolts become the first choice: they penetrate the ground like "steel nails," relying on the gripping force of deep soil for fixation. They save space, are easy to transport, and can withstand dynamic pulling forces.

Material Selection: Stainless Steel

Soft ground is often moist, sometimes even containing acidic substances (e.g., pH value can reach 5.5 after rain on southern lawns).

Therefore, ground anchor bolts are primarily made of 316 stainless steel (containing molybdenum, resistant to chloride ion corrosion), with a diameter of M24 (nominal thread diameter 24mm) and a length of 1.2 meters, of which 90cm is the anchoring section (buried underground) and 30cm is the exposed section (connected to the base).

Actual tests on this specification of bolt, placed in soil with a pH of 4-9 for 3 years, showed surface corrosion of no more than 0.1mm, with tensile strength retention above 98%.

Length and Embedded Depth

Out of the 1.2-meter total length, 90cm is buried underground because the 0-30cm layer is loose (lawn humus, sand surface layer), and this section of the bolt receives almost no force; the 30-120cm layer is dense (undisturbed or compacted soil), where the soil density is high, providing 8-12kPa of lateral pressure.

Calculated with the formula (Pull-out force = Perimeter × Embedded Depth × Lateral Pressure), an M24 bolt with a perimeter of 75.4mm and an embedded depth of 90cm yields a single-bolt pull-out force ≈ 75.4mm × 900mm × 10kPa ≈ 6786N (about 0.68 tons). However, actual tests can reach 15kN (1.5 tons) because the actual soil density is higher than the theoretical value.

Installation Steps

Step one is drilling: use a 26mm diameter hammer drill bit (2mm larger than the bolt, for clearing space) to drill holes at the projection points of the animatronic dinosaur's four limbs (e.g., under the front and hind legs) to a depth of 1.1 meters (10cm more than the bolt's anchoring section to prevent soft soil at the bottom).

Step two is cleaning the hole: use a high-pressure air pump to blow away crushed stones and mud from the hole, otherwise, these debris will occupy 1/3 of the effective anchoring length, directly reducing the pull-out force by 40%.

Step three is embedding and tightening: screw the bolt into the hole until 30cm is exposed, then use a torque wrench to tighten the nut, achieving 120N·m (equivalent to applying 12 kilograms of force to a 1-meter long wrench).

Actual Project Usage

In a city plaza animatronic dinosaur project last year, the total weight was 2.1 tons, and the designed actions included head lifting and stepping. We installed 1 M24 stainless steel ground anchor bolt beneath each of the four limbs, with a spacing of 1.8m × 1.5m (simulating the dinosaur's center of gravity distribution).

A simulation test was conducted after installation: a robotic arm pulled the dinosaur's leg, applying 1.8 tons of pulling force. The bolt displacement was only 2mm (standard allows ≤5mm); another test simulating jumping (1.2 tons of vertical impact force) showed no bolt loosening.

Later, the ground was waterlogged for 3 days during heavy rain, and the pull-out resistance only decreased by 5% in a retest—proving that the 316 stainless steel and correct installation procedure were effective.

Situations Where It Is Not Suitable

If there are tree roots or underground pipes within 1 meter of the ground, or if the soil contains more than 60% sand (e.g., on the edge of a desert), the bolt is prone to loosening, and fine sand cannot fill the gaps.

In such cases, either switch to a thicker M30 bolt (30% higher cost), or use a combination of counterweights + ground anchors. For example, place 2 blocks of 500-kilogram counterweights on each side, supplemented by 2 ground anchor bolts for fixation.

Counterweights for Hard Ground

An animatronic dinosaur's self-weight of 1.8-2.5 tons and the 1.5-2 tons of horizontal thrust generated during walking allow counterweights to suppress the chassis by their own weight. However, counterweights are not just random rocks; their weight, fixing method, and placement are crucial. Mistakes can lead to insufficient suppression, causing the dinosaur to wobble when walking.

Weight and Size

The standard configuration is a single 500-kilogram C30 concrete precast block (dimensions 60×60×40cm). Why C30? This grade of concrete has sufficient compressive strength (30MPa) to withstand the animatronic dinosaur's weight without cracking;

Inside, 4 Φ12mm rebar (spaced 15cm apart) are pre-embedded to prevent cracking during transport or installation—tests showed that blocks without rebar had a corner-chipping probability of over 30% when moved, a problem virtually eliminated with rebar.

The 500-kilogram weight is also deliberate: the animatronic dinosaur's base side length is about 2 meters. Four blocks, totaling 2 tons, are just enough to counteract the horizontal thrust generated during walking.

Using lighter 300-kilogram blocks would require more blocks, making transport more difficult.

Fixing Method

The connection between the counterweight block and the base typically uses two methods: bolt fixing and welding. Bolt fixing uses 8.8-grade M16 bolts (tensile strength 800MPa), with 2 per counterweight block, passing through the L-shaped corner code on the side of the base. The corner code is an 8mm thick steel plate, with bolt holes 10cm from the edge (allowing sufficient stress space).

During installation, the bolts must be tightened to a torque of 80N·m (tightened with a torque wrench, equivalent to 8 kilograms of force applied to a 1-meter wrench), and then secured with double nuts to prevent loosening; anti-loosening adhesive can also be applied. This prevents the bolts from loosening even if the dinosaur jumps.

Installation Time and Position

In actual projects, a 2-ton dinosaur usually has 1 block placed at each of the four corners of the base (spaced 1-1.2 meters apart), totaling 2 tons.

During testing, we used a robotic arm to pull the dinosaur's tail, applying 1.5 tons of horizontal pulling force. The counterweight blocks did not shift, and the bolts did not loosen; if the spacing was increased to 1.5 meters, the counterweight blocks near the pulling point started sliding sideways when the pulling force reached 1.2 tons.

Advantages of Counterweights

The advantages are clear: fast (2 people can move and fix 4 blocks in half an hour), convenient (no drilling, no hammer drill needed), and reusable (can be forklifted directly to the next site).

However, the limitations are also prominent:

• First, transport tools are needed; 500-kilogram blocks cannot be moved by people alone, requiring a rented forklift (200 yuan per hour);

• Second, the ground must be level. If the concrete floor has a 5cm step, placing the counterweight blocks will cause them to tilt, leading to uneven stress and potentially crushing the base corners;

• Third, caution is needed in extreme weather. During a typhoon with 10-level winds (wind speed 25m/s), the counterweight blocks might slide, requiring additional ground anchor bolts for auxiliary fixation.

In a shopping mall plaza animatronic dinosaur project last year, 4 blocks of 500-kilogram counterweights were used, totaling 2 tons, fixed with bolts.

Post-installation test: simulated dinosaur walking, running, and jumping, with a maximum horizontal thrust of 1.8 tons. The maximum displacement of the counterweight blocks was 4mm (standard allows ≤5mm), and the bolt torque remained above 75N·m, with no loosening.

Welded Steel Components

A 2.5-ton animatronic dinosaur on long-term display will experience thermal expansion and contraction deformation of 0.5-1mm per year, and must withstand 10-level wind thrust (25m/s) and occasional minor collisions. Welded steel components, through overall stress design, disperse the stress across the entire steel plate, preventing localized loosening, and can last for over 10 years without major repair.

Custom Steel Plate

Welded steel components primarily consist of two parts: the base flange, which is a steel plate welded to the bottom of the animatronic base, made of 10mm thick Q345 low-alloy steel (dimensions 1.5×1.5 meters). The surface is pre-sandblasted to Sa2.5 grade (roughness 40-75μm) to ensure the weld pool adheres firmly during welding.

The ground pre-embedded plate is a "ground nail" pre-embedded in the concrete foundation, also made of 10mm thick Q345 steel, with dimensions slightly larger than the base flange (1.6×1.6 meters). It is buried 50cm deep, and the concrete foundation must be at least 60cm thick to prevent the pre-embedded plate from being pushed up by freeze-thaw cycles (frozen soil expansion in northern winters).

Why Q345 Steel

The selection of Q345 steel is calculated, not arbitrary. This steel has a carbon content of 0.16-0.22%, with added alloying elements like manganese, silicon, and vanadium. Its tensile strength can reach 470-630MPa (equivalent to withstanding 4.7-6.3 tons of force per square centimeter), which is 20% stronger than ordinary Q235 steel.

Salt spray tests (5% sodium chloride solution, sprayed 8 hours a day) showed that Q345 steel only had 0.01mm of corrosion after 1000 hours, while Q235 steel corroded 0.15mm under the same conditions.

Welding Process

Between the base flange and the pre-embedded plate, 8 fillet welds must be applied (20cm long each, with a leg height of 8mm). The weld type is a full penetration fillet weld, requiring E5015 electrodes (tensile strength 500MPa).

During welding, the current is controlled at 200-220A, voltage at 24-26V, and the interpass temperature must not exceed 200℃.

After welding, ultrasonic testing must be performed (according to GB/T 11345 standard). Level one welds are not allowed to have defects like cracks or lack of fusion, and the compliance rate must be above 99%.

One project cut corners and only performed ordinary weld testing, resulting in the weld cracking after half a year. The animatronic dinosaur base tilted 1.5cm, and the repair cost 30,000 yuan.

Installation Procedure

This installation step demands the highest precision. The ground pre-embedded plate is poured into the concrete 30 days in advance, and its position is calibrated with a total station, with a deviation controlled to within ±2mm.

When the animatronic dinosaur arrives, the base flange must be placed over the pre-embedded plate. Laser positioning equipment is used to check alignment. The bolt holes of the two steel plates must fit perfectly (error ≤1mm), otherwise, the bolts cannot be inserted.

Temporary fixation uses 4 jacks to clamp them tightly. After confirming the correct position, 4 main welds are applied first, followed by 4 triangular stiffeners (12mm thick steel plate, 30cm long, welded between the flange and the pre-embedded plate).

Long-Term Maintenance

A quarterly inspection is required: a magnetic particle flaw detector sweeps the welds for fine cracks; an ultrasonic thickness gauge measures the steel plate thickness. If the annual corrosion exceeds 0.1mm, the paint must be reapplied (epoxy zinc-rich primer + polyurethane topcoat).

In one project, a crack of 0.5mm was found in a weld during the fifth-year inspection of an animatronic dinosaur. The defect was promptly removed with carbon arc air gouging, the groove was re-welded, and flaw detection confirmed compliance.

Actual data speaks for itself: an animatronic dinosaur in a theme park, using this set of welded steel components, underwent a 10-ton horizontal thrust test after installation (simulating an extreme collision). The base displacement was only 3mm (standard ≤5mm);

A year later, a re-check showed no new weld defects, and the steel plate thickness had only reduced by 0.08mm. The shear strength remained above 80kN (about 8 tons of thrust).

This is the capability of welded steel components: high initial investment (40% more expensive than ground anchor bolts), but no major repairs are needed for 10 years, making it more cost-effective in the long run.