AU708999B2 - Method of building construction - Google Patents
Method of building construction Download PDFInfo
- Publication number
- AU708999B2 AU708999B2 AU75377/96A AU7537796A AU708999B2 AU 708999 B2 AU708999 B2 AU 708999B2 AU 75377/96 A AU75377/96 A AU 75377/96A AU 7537796 A AU7537796 A AU 7537796A AU 708999 B2 AU708999 B2 AU 708999B2
- Authority
- AU
- Australia
- Prior art keywords
- screw
- pier
- soil
- swl
- screw pier
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Ceased
Links
- 238000000034 method Methods 0.000 title claims description 12
- 238000009435 building construction Methods 0.000 title 1
- 239000002689 soil Substances 0.000 claims description 18
- 230000006835 compression Effects 0.000 claims description 15
- 238000007906 compression Methods 0.000 claims description 15
- 238000009434 installation Methods 0.000 claims description 3
- 229910000831 Steel Inorganic materials 0.000 claims 1
- 239000010959 steel Substances 0.000 claims 1
- 238000010276 construction Methods 0.000 description 3
- 238000005260 corrosion Methods 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 239000004927 clay Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000011435 rock Substances 0.000 description 1
Landscapes
- Bridges Or Land Bridges (AREA)
Description
THIS INVENTION relates to a method of constructing foundation slabs, particularly suitable for, but not limited to, domestic dwellings.
The foundations for domestic dwellings are usually designed on a once-off basis. While this is expensive, it is necessary to take into account the characteristics of the soil on which the foundation slab is to be laid. Some soils, eg., black soil and clay, are highly reactive and it is not unknown for the uplift force generated, when the soil expands, to exceed the total weight of the dwelling.
It is an object of the present invention to provide a method of slab construction which takes into account the different strengths of soils.
It is a preferred object of the present invention to provide a method of construction which can be used for all soil types.
It is a further preferred object of the present invention to ~provide a method of construction where the slab is supported on :.:""screw piers and the strength of the soil can be determined by the torque required to drive the screw piers into the soil.
Other preferred objects of the present invention will become apparent from the following description.
In a broad aspect, the present invention resides in a
*SS.S.
method of determining the strength of the soil to support a slab wherein: Sll S= the torque required to drive a screw pier, of a particular configuration, into the soil is measured; and the measured torque is compared against predetermined data to calculate the safe working load (SWL) of the screw pier in compression or in compression and in tension.
Preferably, the screw piers are of single-helix, doublehelix or triple-helix configuration.
Preferably, the safe working load (SWL) in compression of a double-helix screw pier is approximately 50% greater than for an to 0. 10 equivalent single-helix screw pier; and the SWL in compression of a triple-helix screw pier is approximately double the SWL of a single helix screw pier for the same applied torque.
too 0 0 Preferably, the SWL in tension of the single helix screw 0000 pier is approximately 75% of its SWL in compression.
Preferably, the eccentricity of the applied load, the ultimate axial load capacity and the ultimate sheet capacity of the screw pier can also be calculated.
To enable the invention to be fully understood, a preferred embodiment will now be described with reference to the accompanying drawings in which: FIG. 1 is a perspective view of a typical single-helix screw pier; FIG. 2 is a schematic side view showing the screw pier
?V
IN
being driven into soil; FIG 3 is a perspective view of the driving machine; FIG 4 is a front view of the hydraulic pressure gauge; FIG 5 is a sketch showing relationship between the effective length (Le) and actual length of the screw pier; and FIG 6 is a graph of the S.W.L. in compression/tension against installation torque for a typical single helix screw pier.
Referring to FIG 1, the screw pier 10 is assembled in sections, where a screw unit 11 has a tubular shaft 12 provided with a single octagonal helix plate 13.
An aggressive point attack bit for rock or shale 14 is engaged in a square drive 15 at the lower end of the shaft 12 and a square drive assembly 16 allows one or more extensions 17 to be connected to the screw unit 11 to achieve the desired length of screw pier 10. Typically, the shaft 12 of the screw unit 11 is 1000mm or 1500mm long, and the shaft(s) 18 of the extension(s) 17 are 1000mm or 2000mm long.
The screw pier 10 illustrated in FIG 1 has a single-helix plate 13, but it will be readily apparent that double- or triple-helix plates 13 may be provided along the shaft 12 at spaced intervals. The l helix plates are typically hexagonal or octagonal in plan view and, eg., of 250-300mm diameter and 8-10mm thickness.
As shown in FIGS 2 and 3, the screw pier 10 is driven into the soil 100 (on which the slab is to be laid or supported) by a driving machine 20 having a hydraulic power head 21 and adaptor 22.
The torque applied to the screw pier 10 can be indicated by a hydraulic pressure gauge 30 (FIG 4) which measures the hydraulic pressure in the lines connecting the power head 21 to a hydraulic pump (not shown), the reading being given in x 100 Nm of applied torque following suitable calibration of the gauge From the Applied Torque, and the effective length (L e of the screw pier 10, where Le 0.7 L (see FIG the following parameters can be calculated for the screw pier 10 from the Tables set out below: Safe Working Load (SWL) in kN for a single helix screw pier in compression and tension; SWL in compression for a double- or triple-helix screw pier; the ultimate axial load capacity N* in kN; and the ultimate shear capacity Vv (kN).
TABLE A SCREW PIERS GEOTECHNICAL CAPACITY Safe Working Load (SWL) in kN 0 1000 10 7.5 75Timm 15 1000 10 7.5 75mm 15 75rr m 2000 20 15 75mm 30 75mm 40 3000 30 25 75mm 45 50mm 80 4000 40 30 75mm 60 50mm 80 5000 50 40 50mm 75 25mm 100 Whilst load testing was performed to Limit State criteria as required by AS2159-1995, the loads in Table A have been converted to safe working load to satisfy convention in the domestic foundation market.
*Limitations: 1. The tests were limited to two specific sites in Sydney.
2. 10mm maximum settlement under SWL.
3. Maximum depth 6000mm.
a a: 4. Minimum depth to achieve minimum torque is 1000mm.
S
5. SWL for Double Triple Helix configuration based a on 1000mm screw piers, coupled together.
TABLE B SCREW PIER STRUCTURAL CAPACITY TO AS 4100 Piers ex 76 x 3.6 CHS grade 250 y galvanised 0.25mm coating (or equivalent corrosion protection).
Non-aggressive corrosive environment (0.6mm corrosion loss).
5*
S
Le(m) e(mm) N*(kN) SWL (kN) Vv (kN) 1 4 115 85 1 20 73 54 1 40 50 37 2 4 95 70 2 20 64 47 2 40 46 34 Reduce load capacity by 20% for mild corrosive environments as defined in AS 2150-1995 Tab 6.4. Screw Piers installed in moderate or severe environments could exhibit less than 50 years serviceable life.
N*(kN) ultimate axial load capacity.
e(mm) eccentricity of applied load in mm. Min 4mm.
SWL(kN) safe working load (working stress) Screw Piers rating.
Vv(kN) ultimate shear capacity.
NOTE: For a SWL of 50kN, screw piers must be installed with a maximum vertical tolerance of 20mm. Maximum effective length of 1.0m. Verticality will not diminish load capacity where a 8 group of screw piers are installed as load redistribution will occur across the slab.
The worst combination of Tab A and Table B shall be used when assessing individual load capacities.
FIG 6 illustrates the S.W.L. in both compression and tension, for a typical single helix screw pier, measured against installation torque.
It will be readily apparent to the skilled addressee that the actual figures in the Tables A and B will be dependent on the types of soil and the configuration of the particular screw piers being used.
Therefore, different tables may be provided for different screw pier configurations.
Various changes and modifications may be made to the embodiments described and illustrated without departing from the scope of the invention.
9* The claims defining the invention are as follows: 1. A method of determining the strength of the soil to support a slab wherein: the torque required to drive a screw pier, of a particular configuration, into the soil is measured; and the measured torque is compared against predetermined data to calculate the safe working load (SWL) of the screw pier in compression or in compression and in tension.
0• 2. A method as claimed in Claim 1 wherein: V 0 9 10 the screw piers are of single-helix, double-helix, or triple- .helix configuration.
3. A method as claimed in Claim 2 wherein: 9999 :ix the safe working load (SWL) in compression of a doublehelix screw pier is approximately 50% greater than for an equivalent single-helix screw pier; and the SWL in compression of a triple-helix *O99*9 screw pier is approximately double the SWL of a single helix screw pier for the same applied torque.
4. A method as claimed in Claim 1 wherein: the SWL in tension of the single helix screw pier is approximately 75% of its SWL in compression.
A method as claimed in any one of Claims 1 to 4 wherein: the effective length of the screw pier is calculated as
Claims (1)
- 6. A method as claimed in Claim 5 wherein: by measuring the eccentricity of the applied load, the ultimate axial load capacity and ultimate shear capacity (Vv) of the screw pier can be calculated from Table B in the description. DATED this eleventh day of June 1999. 10 STEEL FOUNDATIONS LIMITED By its Patent Attorneys FISHER ADAMS KELLY e*° 11 ABSTRACT The strength of the soil (100) to support a concrete slab (200) can be determined by the installation torque required to drive a screw pier (10) into the soil (100). The driving torque of a driving unit (20) is measured and the safe working load (SWL) of the screw pier can be calculated, both in compression and tension, to indicate the soil strength. The ultimate load capacity and ultimate shear capacity (Vv) for the screw pier (10) can be calculated for different degrees of eccentricity of the applied load. 4. *oo* .4
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AU75377/96A AU708999B2 (en) | 1995-12-14 | 1996-12-16 | Method of building construction |
Applications Claiming Priority (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AUPN7150A AUPN715095A0 (en) | 1995-12-14 | 1995-12-14 | Method of building slab construction |
| AUPN7149A AUPN714995A0 (en) | 1995-12-14 | 1995-12-14 | Method of building slab construction |
| AUPN7149 | 1995-12-14 | ||
| AUPN7150 | 1995-12-14 | ||
| AU75377/96A AU708999B2 (en) | 1995-12-14 | 1996-12-16 | Method of building construction |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| AU7537796A AU7537796A (en) | 1997-06-19 |
| AU708999B2 true AU708999B2 (en) | 1999-08-19 |
Family
ID=27156141
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| AU75377/96A Ceased AU708999B2 (en) | 1995-12-14 | 1996-12-16 | Method of building construction |
Country Status (1)
| Country | Link |
|---|---|
| AU (1) | AU708999B2 (en) |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SU1094904A1 (en) * | 1983-02-11 | 1984-05-30 | Ордена Октябрьской Революции Всесоюзный Государственный Проектно-Изыскательский И Научно-Исследовательский Институт Энергетических Систем И Электрических Сетей "Энергосетьпроект" | Method of determining load-bering capacity of screw anchor |
| AU4426893A (en) * | 1992-07-28 | 1994-02-03 | Joslyn Manufacturing Company | Anchor holding capacity indicator |
| JPH08113937A (en) * | 1994-10-14 | 1996-05-07 | Nitto Seiko Co Ltd | Automatic penetration test method |
-
1996
- 1996-12-16 AU AU75377/96A patent/AU708999B2/en not_active Ceased
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SU1094904A1 (en) * | 1983-02-11 | 1984-05-30 | Ордена Октябрьской Революции Всесоюзный Государственный Проектно-Изыскательский И Научно-Исследовательский Институт Энергетических Систем И Электрических Сетей "Энергосетьпроект" | Method of determining load-bering capacity of screw anchor |
| AU4426893A (en) * | 1992-07-28 | 1994-02-03 | Joslyn Manufacturing Company | Anchor holding capacity indicator |
| JPH08113937A (en) * | 1994-10-14 | 1996-05-07 | Nitto Seiko Co Ltd | Automatic penetration test method |
Also Published As
| Publication number | Publication date |
|---|---|
| AU7537796A (en) | 1997-06-19 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| ON | Decision of a delegate or deputy of the commissioner of patents (result of patent office hearing) |
Free format text: OPPOSITION UNDER SECTION 59. APPLICATION FOR AN EXTENSION OF TIME IN WHICH TO SERVE EVIDENCE IN ANSWER. THE REQUESTED THREE MONTH EXTENSION IS REFUSED. HOWEVER, A LIMITED EXTENSION OF TIME OF SEVEN DAYS IS GRANTED TO ALLOW THE APPLICANT TO SERVE WHATEVER EVIDENCE IT HAS TO HAND. Opponent name: SOILTEST AUSTRALIA PTY LTD. Effective date: 20010111 |
|
| ON | Decision of a delegate or deputy of the commissioner of patents (result of patent office hearing) |
Free format text: OPPOSITION UNDER SECTION 59. APPLICATION FOR AN EXTENSION OF TIME IN WHICH TO SERVE EVIDENCE IN ANSWER (REGULATION 5.10(2)). THE REQUESTED THREE MONTH EXTENSION IS REFUSED. HOWEVER, A LIMITED EXTENSION OF TIME OF SEVEN DAYS IS GRANTED TO ALLOW THE APPLICANT TO SERVE WHATEVER EVIDENCE IT HAS TO HAND. Opponent name: SOILTEST AUSTRALIA PTY LTD. Effective date: 20010111 |
|
| ON | Decision of a delegate or deputy of the commissioner of patents (result of patent office hearing) |
Free format text: MR. CAMILLERI WAS THE ACTUAL INVENTOR OF THE INVENTION, AND STEEL FOUNDATIONS WAS ENTITLED TO THE GRANT OF A PATENT FOR THE INVENTION. THE OPPOSITION SUCCEEDED ON THE GROUNDS OF NOVELTY AND INVENTIVE STEP. SEVERAL SECTION 40 DEFECTS WERE ALSO FOUND IN THE SPECIFICATON. THE APPLICATION WAS REFUSED. Opponent name: SOILTEST AUSTRALIA PTY LTD Effective date: 20010809 |
|
| CR | Opposition proceedings - application refused |
Opponent name: SOILTEST AUSTRALIA PTY LTD |
|
| MK16 | Application refused |