Custom Soil Testing Equipment

The customer approached us with a request to develop a triaxial compression testing rig for soil analysis. The project required the design of both a stabilometer chamber and a load application system. The goal was to deliver a solution that provided a competitive edge while meeting the international standard for such tests—ISO 3601-2. Existing market alternatives could not operate at pressures as high as 16 atm. Additionally, the customer’s product team emphasized addressing user complaints about competitor solutions, particularly regarding the cumbersome and time-consuming process of loading soil samples. The presence of competitors also necessitated cost-efficient design and logistics to ensure the customer’s business model remained viable.

Stabilometer Chamber Design

The stabilometer chamber comprises a base, body, rod, upper and lower punches, drainage and pressure system pipelines, and an indicator. A critical design requirement was selecting a transparent material for the body capable of withstanding pressures of up to 16 atm. To ensure durability, we conducted computational simulations to test material strength and determine the optimal placement of the fixation mechanism. Ultimately, we selected a mineral glass tube, which outperformed other materials, such as acrylic glass, in terms of strength.

In existing market solutions, the chamber body is typically secured using bolts that attach a metal lid (an approach that complicates usage, as filling the chamber with soil takes 4–5 minutes). We proposed an alternative locking method that eliminated the need for hand tools while preserving sealing reliability. After a series of simulations, we optimized the geometry and placement of the locking mechanism. As a result, we cut preparation time in half and removed the need for wrenches during setup.

A key design challenge was to ensure a reliable, cost-effective seal between the lower flange and the chamber base. We addressed this by developing and validating a sealing approach using an elastic element operating within a controlled gap. This solution ensures tightness under compression while avoiding the need for complex surface machining.

For the chamber’s moving component, we applied a sealing solution suitable for variable loads. We selected an element resistant to abrasion and capable of maintaining tightness under displacement.

Another key challenge was to ensure a reliable and stable connection for the latex tubing used to apply load to the soil sample. While rubber rings are commonly used in similar chambers, the client highlighted several shortcomings of such solutions in competitor products and provided specific requirements to ensure uniform contact between the plunger and tubing at the attachment point. To meet these requirements, we designed a spring-loaded clamping element with adjustable force. This solution prevents localized deformation and provides consistent, leak-free sealing under dynamic operating conditions.

The chamber also includes a dedicated sleeve for connecting a temperature sensor.

To validate our design, we produced a stabilometer chamber prototype, which met all functional and performance requirements.

Load Application System Design

Upon completing the stabilometer chamber, we began designing the load application system, which is based on an electric drive. The system features two parallel jacks with gear reducers that apply the required loading force, mounted on a shared crossbeam. Feedback is provided by a load cell. The system is designed to accommodate a cylindrical load object with a diameter of 200 mm and a height of 280 mm between the actuators. Stepper motors were chosen to synchronize the movement of the parallel actuators, preventing misalignment under load.

Project Deliverables and Next Steps

We delivered the customer a complete set of engineering documentation for the load application system and a fully functional stabilometer chamber. The manufacturing of the load application system is currently underway—stay tuned for updates!