SOIL TREATMENT

Abstract

A method of treatment of foundation soil beneath a structure, comprising treating the foundation soil with an ionic treatment agent, and treating the foundation soil with a soil stabiliser to stabilise the foundation soil.

Claims

1. A method of treatment of foundation soil beneath a structure, comprising treating the foundation soil with an ionic treatment agent, and treating the foundation soil with a soil stabiliser to stabilise the foundation soil.

2. A method as claimed in claim 1, wherein the soil stabiliser forms a solid or a gel in the foundation soil and thereby stabilises it.

3. A method as claimed in claim 1, wherein the respective treatments are carried out sequentially.

4. A method as claimed in claim 3, wherein the treatment with the ionic treatment agent is carried out before the treatment with the soil stabiliser.

5. A method as claimed in claim 3, wherein the treatment with the soil stabiliser is carried out before the treatment with the ionic treatment agent.

6. A method as claimed in claim 1, wherein the respective treatments are carried out simultaneously.

7. A method as claimed in claim 1, wherein the respective treatments are carried out on the same portion of the foundation soil.

8. A method as claimed in claim 1, wherein the treatment with the ionic treatment agent is carried out on a first portion of the foundation soil above a second portion of the foundation soil, and the treatment with the soil stabiliser is carried out on the second portion.

9. A method as claimed in claim 8, wherein the soil stabiliser in the second portion expands to cause compression of the first portion.

10. A method as claimed in claim 8, wherein the soil stabiliser is discharged into the second portion at a pressure which causes compression of the first portion.

11. A method as claimed in claim 1, wherein the treatment with the ionic treatment agent is carried out on a first portion of the foundation soil below a second portion of the foundation soil, and the treatment with the soil stabiliser is carried out on the second portion.

12. A method as claimed in claim 1, comprising injecting the ionic treatment agent into the foundation soil and injecting the soil stabiliser into the foundation soil.

13. A method as claimed in claim 12, wherein tubes are used to inject the ionic treatment agent and the soil stabiliser into the foundation soil.

14. A method as claimed in claim 1, wherein the treatment with the ionic treatment agent is carried out directly under a central region of a slab of the structure.

15. A method as claimed in claim 1, further comprising treating soil around a perimeter of the structure with the ionic treatment agent.

16. A method as claimed in claim 1, wherein the soil stabiliser comprises polyurethane.

17. A method as claimed in claim 1, wherein the soil stabiliser comprises acrylic.

18. A method as claimed in claim 1, wherein the soil stabiliser comprises silicate.

19. A method as claimed in claim 1, wherein the soil stabiliser comprises a material which expands in the foundation soil.

20. A method as claimed in claim 1, wherein the soil stabiliser fills at least some pore spaces in the foundation s

Description

EXAMPLE

[0099] The foundation soil is treated using AGSS-ICS as an ionic treatment agent. Through cation exchange the ionic treatment agent removes the ability of clay particles to attract and hold on to water. The soil will now become less cohesive and this makes the soil free draining and allows the soil stabiliser to pass more freely through the soil into pores between the particles.

[0100] The foundation soil is injected with the soil stabiliser. Depending on the strength requirement of the foundation and characteristics of the soil, the stabiliser may be a single component moisture activated foaming polyurethane, a plural component foaming or non-foaming polyurethane, a colloidal silica, acrylic, etc. The stabiliser will create a homogenous, strong and water resistant foundation/underpin.

[0101] If additional lift is required, this can be achieved through: [0102] 1. Slab jackinginjecting plural component polyurethane foam through holes drilled directly into the footing. The foam is injected into the region above the newly stabilised foundation soil and uses it as a base on which to push. The slab jacking is used as a final step to fine tune the lift and ensure continuous support of the structure. Slab jacking can alternatively or additionally be carried out at any stage in the process (e.g., to fill voids beneath a raft footing) prior to the treatment with the ionic treatment agent or after that treatment and prior to the treatment with the soil stabiliser. [0103] 2. Deep injection of a plural component polyurethane, in accordance with the first known remedial system discussed above. This would be installed to raise the structure.

[0104] In some embodiments, the deep injection of a plural component polyurethane may negate the need to stabilise the portion of the soil which has been treated with the ionic treatment agent. In other words, a first portion of the soil below the structure may be treated with ionic treatment agent, and then lower down, at the base level of that first portion, a second portion of the soil below the structure may be treated with the soil stabiliser.