Ground Freezing Patents: Leaders, Trends & White Space 2026
Filing growth compares 2021 (11 records) with 2024 (6) — a three-year span. 2024 is the most recent year we treat as complete: publication lags filing by roughly 18 months, so 2025 onwards are still filling in and any growth rate that ends there would understate the field. Top-5 share is the combined record count of the five largest assignees divided by all 343 records in scope (CR5), not by the ranked leaders only.
What the artificial ground freezing patent record shows
Artificial ground freezing turns unstable or waterlogged ground into a temporary structural barrier by circulating a coolant through freeze pipes until the surrounding soil forms an ice wall. The technique shows up across two adjacent patent classes: foundation and earth-drilling engineering, where freeze pipes and casings are claimed as construction hardware, and tunnel and shaft support, where the frozen wall itself is the engineering objective. The 343 records in scope span 2015 through the current filing year, drawn from a search built around ground freezing methods, frozen soil walls and soil freezing techniques.
Filing activity is uneven rather than steadily rising or falling. It peaked in 2018 and has since receded, while the assignee base stays split between a handful of construction majors filing repeatedly and a much larger group of single-record entrants — universities, regional contractors and equipment makers testing the space once and not returning.
Filing trend and technology composition
Two views of the same 343 records: how filing activity has moved year over year, and how the underlying claims split across IPC subclasses.
Filing trend, 2017-2026
Filings ran from 10 in 2017 to a peak of 22 in 2018, then eased; the tracked span from 2021 (11) to 2024 (6) shows a 45% decline, the last window unaffected by publication lag. 2025 and 2026 are undercounted because publication typically lags filing by around 18 months.
IPC subclass distribution
E02D (foundations & earth drilling) and E21D (shafts, tunnels & mine support) between them touch most records, at 59.5% and 36.7% of the 343 in scope respectively. Material analysis (G01N, 8.5%), well drilling (E21B, 5.5%) and geophysics (G01V, 3.5%) are present but thin, and since a record can carry several classes these shares add up to more than 100%.
Shares are the percentage of the 343 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Tunneling & Underground Engineering: Artificial Ground Freezing Patent Landscape with Eureka
This page is one run against one query. Ask Eureka your own question about tunneling & underground engineering: artificial ground freezing patent landscape and every answer comes back with the patent numbers behind it.
Try EurekaRepresentative filing and most-cited prior art
Artificial ground freezing method and artificial ground freezing system
US10221537B2, assigned to Chemical Grouting Co., Ltd. and published 2019-03-05, claims a freeze-pipe and coolant-circulation-pipe arrangement using carbon dioxide as the circulating coolant rather than a gas-phase refrigerant, aimed at improving thermal efficiency without venting coolant into the ground or air.Abstract text drawn directly from the published filing.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US3943722A | Ground freezing method | 132 |
| 2 | US5730550A | Method for placement of a permeable remediation zone in situ | 111 |
| 3 | US6796139B2 | Method and apparatus for artificial ground freezing | 53 |
| 4 | CN103969282A | 一种研究冻融土温度场、水分迁移及变形规律试验装置 | 40 |
| 5 | JP1991005600A | Method and device for constructing branch and connection part of shield tunnel and its segment | 40 |
| 6 | CN104316391A | 模拟人工地层冻结法的冻融试验模型装置及方法 | 38 |
| 7 | JP1988002932A | Powdery composition for nasal administration | 38 |
| 8 | JP2005264717A | Ground freezing method | 33 |
| 9 | JP1992281990A | Method and apparatus for expanding pit width by shield excavator | 33 |
| 10 | JP1988115821A | Powdery composition for nasotracheal administration containing basic amino acid | 33 |
Citation counts favour older filings simply because they have had longer to be cited; treat this table as a map of influential prior art, not of current filing activity.
Patent titles are shown in the language they were filed in, not translated, so that each record stays verifiable against the original filing — a translated title will not match in Eureka or in any national register. Each row carries its publication number; clicking a row searches Eureka by that number.
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Browse MCP servers →What the numbers mean for a filing decision
Three read-throughs of the dataset: where claim density sits, what the citation table signals, and how the receiving-office split shapes where to search and file.
A dense core, a long tail behind it
The leading assignee holds 25 records and the field drops to 12 by fifth place, then to 10 by tenth — a real gap at the top but not a monopoly. Combined, the ranked leaders through tenth place hold 45.2% of all records, meaning more than half the field is spread across the remaining assignees, many with only one or two filings.
Foundation hardware outpaces tunnel-support claims
More records claim freeze-pipe and casing hardware under foundations and earth drilling than claim the frozen structure itself under tunnel and shaft support. That split matters for freedom-to-operate: hardware claims in E02D are the denser thicket, while the tunnel-support side carries more room for method-level differentiation.
Activity has cooled from its 2018 peak
Filings peaked at 22 in 2018 and the tracked 2021-2024 window shows a 45% decline to 6. That is the last window unaffected by publication lag; 2025-26 counts will rise as later filings publish, so read the recent taper cautiously rather than as a closed trend.
Filing activity concentrates in Japan and China
Japan accounts for 177 records and China 69, together dwarfing the United States (24), South Korea (14), Canada (11) and the EPO (9). A freedom-to-operate search that skips Japanese-language prior art is searching a small fraction of the relevant record.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to tunneling & underground engineering: artificial ground freezing patent landscape, with the prior art for and against each one.
Where to take this analysis
The dataset points to a few concrete next steps depending on what you are trying to decide.
Run a freedom-to-operate check on freeze-pipe hardware
E02D's 59.5% share of records means most claim density sits in casing and coolant-circulation hardware. Before designing a new freeze-pipe system, map the leading assignees' claims in this subclass specifically.
Explore this in EurekaSearch Japanese-language prior art directly
With 177 of the receiving-office filings routed through Japan, an English-only search misses the majority of the relevant record. A translation-aware search pass is worth the extra step before filing.
Explore this in EurekaTest claims in the under-claimed branches
Thermal monitoring, geophysical integration and branch-tunnel freezing all show thin filing density relative to the core classes. These are the areas where a first-mover claim is more likely to clear prior art.
Explore this in EurekaCommon questions about artificial ground freezing patents
This dataset tracks 343 published records filed between 2015 and the 2026 cut-off, built from a search covering ground freezing methods, frozen soil walls and soil freezing techniques. That figure counts patent families/records, not raw documents, so it filters out duplicate continuations and multi-jurisdiction refilings of the same invention. It is a scoped count tied to this specific search string, not a total for every ground-freezing-adjacent filing worldwide.
The assignee ranking covers 100 companies, with the leading filer holding 25 records and a fast drop-off to 12 by fifth place and 10 by tenth. The top five combined hold 28.6% of all 343 records in scope, and the top ten hold 45.2%, which means more than half the field is spread thinly across the remaining ranked assignees. Most of these are construction contractors and engineering firms based in Japan, consistent with Japan's dominant 177-record receiving-office share.
The two dominant IPC subclasses are E02D (foundations & earth drilling), present on 59.5% of the 343 records, and E21D (shafts, tunnels & mine support), present on 36.7%. Material analysis and testing (G01N), well drilling (E21B) and geophysical surveying (G01V) each appear on a smaller share, generally under 10%. Because a single record can carry several IPC codes, these shares add up to more than 100% and should not be summed into a total.
Filings peaked at 22 in 2018 and the most recent complete comparison window, 2021 to 2024, shows a 45% decline from 11 to 6 filings. That said, publication typically lags filing by around 18 months, so the 2025-26 counts in any live dataset will understate true recent activity and should not be read as proof the field has gone quiet. The honest read is a cooling trend through 2024, with the very latest years still an open question.
US10221537B2, assigned to Chemical Grouting Co., Ltd. and published in 2019, claims a freeze-pipe and coolant-circulation arrangement that uses carbon dioxide rather than a gas-phase refrigerant as the circulating coolant, aimed at improving thermal efficiency without venting coolant into the ground or air. It blocks a fairly specific combination — CO2 as the circulating medium plus the described dual-pipe casing arrangement — rather than ground freezing broadly. Designers using different coolants or pipe configurations have room to work around it, but should check it directly against any CO2-based freeze-pipe design.
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Disclaimer. This page is generated from Patsnap Eureka data drawn from a limited snapshot of global patent and scientific-literature records, and is provided for general information and reference only.
Patent data carries inherent limitations: recent filings (typically the most recent 18–24 months) are under-counted due to standard publication lag; counts may be reported at either a patent-family or a patent-record basis and are not always directly comparable; classification, applicant-name, and citation data may contain errors, duplicates, or omissions; and the underlying search query defines and constrains the scope shown. As a result, the analysis may be incomplete or inaccurate and may not reflect the full technology landscape.
Nothing on this page constitutes an exhaustive prior-art, novelty, freedom-to-operate, or validity search, nor does it constitute legal, financial, investment, or professional advice, and it should not be relied upon as such. Any patent, commercial, or strategic decision should be verified independently and reviewed with qualified patent, legal, and domain professionals. Patsnap makes no warranties, express or implied, as to the accuracy, completeness, or fitness for any particular purpose of the information presented.
Machine translation. Assignee and organisation names originally recorded in Chinese, Japanese or Korean have been rendered into English by an AI translation step so that the tables stay readable. These renderings are best-effort and may not match a company’s registered English name; the original name is what the underlying patent record carries, and it is what any Eureka query launched from this page uses.