What Static Cone Penetration Testing Is: Method, Equipment, Use

Static cone penetration testing (CPT) is field pushing of a cone probe with continuous recording of tip resistance qc and sleeve friction fs. The method does not replace drilling: it gives a continuous property profile with depth without recovering core. For pile foundations and heterogeneous sections it is often the main field tool. In Aktau and Mangystau Region CPT tightens the boundaries of weak and saline layers that a sparse borehole grid can miss.

This article is for designers and survey clients: how the method works under GOST 19912-2012, what equipment is used, where probing works and where it is swapped for dynamic testing.

How the Test Is Run

Under GOST 19912-2012 static probing is continuous pushing of the probe into dispersed soil at about 1.2 ± 0.3 m/min. Breaks are allowed only to add rods. The standard covers natural, man-made and frozen dispersed soils into which the probe can be pushed continuously. Do not use static CPT if the soil contains more than 25 % of particles coarser than 10 mm: the cone will not penetrate and the profile is meaningless.

At each depth the crew records:

• qc — soil resistance under the cone (strength, density);
• fs — resistance on the friction sleeve;
• pore pressure (CPTu) if the brief explicitly requires it.

From the qc/fs ratio the geologist picks layers, estimates clay consistency and sand density, and selects design parameters for piles. Layer classification is tied to GOST 25100-2020 and borehole data: probing without lithology is a set of curves, not a section.

The composition of geotechnical surveys is set by SP RK 1.02-102-2014. Field versus laboratory methods are compared in field vs laboratory soil tests.

Equipment and Depth

GeoProGlobal uses a static CPT spread from its own fleet. Typical parameters:

Parameter	Value on our units
Type	CPT, cone pushing
Recorded quantities	qc · fs
Depth	usually to 20 m and beyond — by section and refusal
Soils	sands, sandy loams, loams, clays, peats
Standard	GOST 19912-2012

“Refusal” means the probe will not advance at the allowable thrust: dense gravel, crushed stone, rock. That is not a method failure; it is the limit of applicability. Beyond it you drill or switch to dynamic probing.

On the weak Caspian soils of Mangystau CPT is strong precisely because a continuous profile catches thin silt lenses and fills that a borehole every 20–30 m may miss.

The spread card is in the equipment catalogue. The service is field soil testing.

Where the Designer Needs CPT

Pile and piled-raft foundations. Shaft resistance uses the qc/fs profile, not a single parameter “from borehole depth”.

Section refinement. Geotechnical-element boundaries are set on qc jumps, then confirmed with samples. Fewer spare boreholes, fewer missed weak lenses.

Linear assets. Soils change along a pipeline or road. A CPT grid between boreholes is cheaper than drilling every 50 m.

Fill and backfill control. Repeat probes show whether a layer has densified.

CPT does not close:

• surface deformation modulus — that is the Izyskatel 600 / 5000 plate under GOST 20276-2012;
• parameters at borehole depth where a plate cannot sit — the PEV-89MK pressuremeter;
• gravelly and coarse soils — dynamic probing (DPT), blows per 10 cm.

Before a foundation design, CPT usually sits in the programme with drilling, not instead of it. See engineering geology for foundations.

What Goes in the Report

The client receives probing profiles, qc/fs tables by depth, layer interpretation and design parameters aligned with the laboratory. These materials enter the technical survey report and go to expert review with borehole logs.

FAQ

Does CPT replace drilling? No. No samples — no classification and no chemistry. Probing supplements boreholes.

Can we order only static CPT? Yes, if the brief is written that way (for example densifying a grid on an already drilled pad).

Why did the probe stop at 8 metres? A coarse layer or thrust refusal. Next is a borehole or DPT, not “push at any cost”.

How many points are needed? The survey programme sets this from complexity category and structure type, not a price list “from three probes”.

Conclusion

Static CPT is a continuous soil-strength profile under GOST 19912-2012. It speeds and tightens surveys for piles and heterogeneous sections, but it only works in dispersed soils without a coarse skeleton. In Aktau and Mangystau Region CPT is especially useful on the weak and saline Caspian sequence.

GeoProGlobal runs CPT, DPT, plate and pressuremeter tests together with drilling. To put probing into the brief for your site, submit a request on the quote page.