EP0338865B1 - Apparatus for supporting the walls of trenches - Google Patents
Apparatus for supporting the walls of trenches Download PDFInfo
- Publication number
- EP0338865B1 EP0338865B1 EP19890304022 EP89304022A EP0338865B1 EP 0338865 B1 EP0338865 B1 EP 0338865B1 EP 19890304022 EP19890304022 EP 19890304022 EP 89304022 A EP89304022 A EP 89304022A EP 0338865 B1 EP0338865 B1 EP 0338865B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- strut
- shoring
- spring
- panel
- cylinder
- 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.)
- Expired - Lifetime
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Classifications
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D17/00—Excavations; Bordering of excavations; Making embankments
- E02D17/06—Foundation trenches ditches or narrow shafts
- E02D17/08—Bordering or stiffening the sides of ditches trenches or narrow shafts for foundations
Definitions
- This invention relates to apparatus for supporting the walls of trenches, or other excavations, and of the kind generally designated as a trench shoring box and comprised of two opposed shoring panels provided with vertically directed support members to which two opposite ends of struts of adjustable length, normally extending substantially perpendicularly to the shoring panels, are horizontally pivotally attached so that the shoring panels can be relatively displaceable in the vertical direction as excavation progresses.
- FR-A-2 195 240 discloses - in Fig. 3 thereof and the related description - apparatus for supporting the walls of trenches, or other excavations, and of the kind generally designated as a trench shoring box and comprised of two opposed shoring panels provided with vertically directed support members to which two opposite ends of struts of adjustable length, normally extending substantially perpendicularly to the shoring panels, are horizontally pivotally attached so that the shoring panels can be relatively displaceable in the vertical direction as excavation progresses, wherein each strut is additionally resiliently coupled to the shoring panel by a leaf spring which is adapted to dampen angular movement between the strut and the panel, a portion of the leaf spring being secured to the end of the strut and extending perpendicularly thereto, a remote end of the leaf spring being connected to the shoring panel, the spring exerting damping action against deviations of the strut from its normal position substantially perpendicular
- opposite halves of the leaf spring in Fig. 3 of FR-A-2 195 240 are prestressed to act in opposition to each other, so that any deviation of the panel from its normal angular position relative to the strut is aided by one half of the spring, which half depending upon the direction of the deviation, and opposed by the other half of the spring.
- both halves of the spring are greatly curved, with a puzzling effect. It appears that the strut is constrained to pivot about the the pin at the centre of the boss in FR-A-2 195 240, so that there would be circumferential movement of the curved spring, moving one extreme end of the spring out of the associated slot and transferring the reaction to the adjacent bar. The other extreme end of the spring would be pushed deeper into the associated slot, also causing eventual reaction from the adjacent bar. Apparently there is no end stop to limit angular deviation.
- leaf spring in Fig. 3 of FR-A-2 195 240 appears to be of spring steel and yet shown welded to the strut and not to the boss, which is not good practice.
- the present invention has been devised with the general object of providing a damping system which does not have the above mentioned disadvantages.
- each spring is substantially rectilinear, so that substantially the entire spring extends substantially parallel to the shoring panel, and in that substantially the entire spring opposes any deviation of the strut, in either direction, from its normal position in which the strut is substantially perpendicular to the panel.
- Fig. 1 shows a heavy duty strong box strut which comprises a central cylinder 1 formed in two cylindrical parts A, B, with abutting flanges 2, 3 secured together by bolts 4 and nuts 5 and each formed from end to end internally with a quick feed screw thread 6.
- a pair of thrust rods 9, 10 Retained within the cylinder parts A and B, are the correspondingly screw-threaded cylindrical heads 7, 8 of a pair of thrust rods 9, 10.
- Attached to the outward end of each of these thrust rods 9, 10 is a perpendicular plate 13 which supports a central part of a multi-leaf spring 12 which is clamped thereto by a second plate 11 by means of bolts 14 and nuts 15, so that the leaf spring 12 extends perpendicularly to the strut.
- each plate 11 Attached to the outward side of each plate 11 is a U-shaped saddle 16 by which the strut is swivelably mounted on an horizontal pin 17 which, as shown in Fig. 2, extends between a pair of end post plates or brackets 18 which project at right angles from a shoring panel 20, and which are part of an end post 19 fixed to the shoring panel 20 as shown in Fig. 4.
- each leaf spring is located in slotted tubes 21 which are welded between the end post plates or brackets 18 of the side panel 20, these details being shown more clearly in Fig. 2, and also in Figs. 3 and 4.
- the centre lines C of the struts are indicated in Fig. 4.
- Rapid extending or retracting of each strut is effected by turning the cylinder 1 in a clockwise or counter-clockwise direction by use of any suitable tool such as for instance a lever arm inserted into one or other of four radial openings in a collar 22 which is welded to the cylinder part B.
- Fig. 1 there is also illustrated by a chain-dashed line a lifting bracket which is attached only to the topmost extension strut.
- the construction is of course such that none of the screw-threading is exposed in use to the environment in which the shoring box operates. Also, in the formation of the screw threading, the minimum amount of metal is removed from the cylinder parts A, B consistent with the maximum designed load-carrying capacity of the strut. This will provide greater local strength and will minimise the possibility of dents being formed in the cylinders during normal use of the struts.
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- Engineering & Computer Science (AREA)
- Mining & Mineral Resources (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Paleontology (AREA)
- Civil Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Structural Engineering (AREA)
- Springs (AREA)
- Tents Or Canopies (AREA)
- Buildings Adapted To Withstand Abnormal External Influences (AREA)
- Forms Removed On Construction Sites Or Auxiliary Members Thereof (AREA)
Description
- This invention relates to apparatus for supporting the walls of trenches, or other excavations, and of the kind generally designated as a trench shoring box and comprised of two opposed shoring panels provided with vertically directed support members to which two opposite ends of struts of adjustable length, normally extending substantially perpendicularly to the shoring panels, are horizontally pivotally attached so that the shoring panels can be relatively displaceable in the vertical direction as excavation progresses.
- It has been appreciated that during normal handling of a fully assembled trench shoring box there is considerable differential movement between each of the shoring panels and due to the weight of the assembly unless some damping restraint is provided considerable shock forces are applied at the limits of angular movement between the struts and the panels. Various damping assemblies for this purpose have hitherto been employed, such as for instance hydraulically operating dampers or by the provision of two helical springs positioned equally one each side of each strut centre line, but these have not proved entirely satisfactory. For instance with a damping system embodying two helical springs, one spring only at a time can contribute to the damping action. Also in this damping system the stiffness of the damper is fixed by the geometry of the spring which cannot easily be changed to accommodate extremes of use.
- FR-A-2 195 240, on which the preamble of claim 1 is based, discloses - in Fig. 3 thereof and the related description - apparatus for supporting the walls of trenches, or other excavations, and of the kind generally designated as a trench shoring box and comprised of two opposed shoring panels provided with vertically directed support members to which two opposite ends of struts of adjustable length, normally extending substantially perpendicularly to the shoring panels, are horizontally pivotally attached so that the shoring panels can be relatively displaceable in the vertical direction as excavation progresses, wherein each strut is additionally resiliently coupled to the shoring panel by a leaf spring which is adapted to dampen angular movement between the strut and the panel, a portion of the leaf spring being secured to the end of the strut and extending perpendicularly thereto, a remote end of the leaf spring being connected to the shoring panel, the spring exerting damping action against deviations of the strut from its normal position substantially perpendicular to the shoring panel.
- However, opposite halves of the leaf spring in Fig. 3 of FR-A-2 195 240 are prestressed to act in opposition to each other, so that any deviation of the panel from its normal angular position relative to the strut is aided by one half of the spring, which half depending upon the direction of the deviation, and opposed by the other half of the spring. Moreover, both halves of the spring are greatly curved, with a puzzling effect. It appears that the strut is constrained to pivot about the the pin at the centre of the boss in FR-A-2 195 240, so that there would be circumferential movement of the curved spring, moving one extreme end of the spring out of the associated slot and transferring the reaction to the adjacent bar. The other extreme end of the spring would be pushed deeper into the associated slot, also causing eventual reaction from the adjacent bar. Apparently there is no end stop to limit angular deviation.
- Also, the leaf spring in Fig. 3 of FR-A-2 195 240 appears to be of spring steel and yet shown welded to the strut and not to the boss, which is not good practice.
- The present invention has been devised with the general object of providing a damping system which does not have the above mentioned disadvantages.
- The apparatus of the present invention is characterised in that each spring is substantially rectilinear, so that substantially the entire spring extends substantially parallel to the shoring panel, and in that substantially the entire spring opposes any deviation of the strut, in either direction, from its normal position in which the strut is substantially perpendicular to the panel.
- In order however that the invention may be more readily understood reference should be made to the following description of a preferred embodiment which is illustrated in the accompanying drawings. In these drawings:-
- Fig. 1 is a side elevation, partly in section, of an adjustable length strut for attachment between opposite shoring panels;
- Fig. 2 is a plan view of a shoring panel end post showing the mode of connection of an adjustable length strut thereto;
- Fig. 3 is an elevation view on the inside of a shoring panel; and
- Fig. 4 is an elevation view on arrow IV in Fig. 3.
- Referring now to the drawings, Fig. 1 shows a heavy duty strong box strut which comprises a central cylinder 1 formed in two cylindrical parts A, B, with abutting
flanges bolts 4 andnuts 5 and each formed from end to end internally with a quickfeed screw thread 6. Retained within the cylinder parts A and B, are the correspondingly screw-threaded cylindrical heads 7, 8 of a pair ofthrust rods thrust rods perpendicular plate 13 which supports a central part of amulti-leaf spring 12 which is clamped thereto by asecond plate 11 by means ofbolts 14 andnuts 15, so that theleaf spring 12 extends perpendicularly to the strut. Attached to the outward side of eachplate 11 is aU-shaped saddle 16 by which the strut is swivelably mounted on anhorizontal pin 17 which, as shown in Fig. 2, extends between a pair of end post plates orbrackets 18 which project at right angles from ashoring panel 20, and which are part of anend post 19 fixed to theshoring panel 20 as shown in Fig. 4. - The ends of each leaf spring are located in
slotted tubes 21 which are welded between the end post plates orbrackets 18 of theside panel 20, these details being shown more clearly in Fig. 2, and also in Figs. 3 and 4. The centre lines C of the struts are indicated in Fig. 4. - Rapid extending or retracting of each strut is effected by turning the cylinder 1 in a clockwise or counter-clockwise direction by use of any suitable tool such as for instance a lever arm inserted into one or other of four radial openings in a
collar 22 which is welded to the cylinder part B. - In Fig. 1 there is also illustrated by a chain-dashed line a lifting bracket which is attached only to the topmost extension strut.
- It will be appreciated that adjustment of the length of a strut is based on the turnbuckle or bottlescrew principle but it is a requirement that strut release should be rapid. A satisfactory screw thread pitch for the elements A, B, 7, 8 would be one which alters the strut length by 48 mm for each revolution of the cylinder 1.
- The construction is of course such that none of the screw-threading is exposed in use to the environment in which the shoring box operates. Also, in the formation of the screw threading, the minimum amount of metal is removed from the cylinder parts A, B consistent with the maximum designed load-carrying capacity of the strut. This will provide greater local strength and will minimise the possibility of dents being formed in the cylinders during normal use of the struts.
- It is characteristic of the invention, and advantageous that:
- a) Any deviation of the strut, in either direction, from its normal position perpendicular to the
panel 20, results in restraining action by both halves of theleaf spring 12, that is, the upper spring half and the lower spring half, relative to thehorizontal pin 17; - b) The stiffness of each spring is easily changed by the addition or reduction of the number of leaves;
- c) The spring may be shaped to give the maximum stiffness for each leaf, or may be shaped to approach the configuration of constant strength, whereby the stiffness is reduced for the same thickness.
- d) To guard against injury, in the event of the spring leaves breaking, a guard leaf of a ductile steel may be fitted on the clear side of the spring leaf assembly to prevent a piece of the more elastic and brittle steel spring from flying out and causing personal injury.
Claims (6)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB8809439A GB2217750B (en) | 1988-04-21 | 1988-04-21 | Apparatus for supporting the walls of trenches |
GB8809439 | 1988-04-21 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0338865A1 EP0338865A1 (en) | 1989-10-25 |
EP0338865B1 true EP0338865B1 (en) | 1992-06-17 |
Family
ID=10635588
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19890304022 Expired - Lifetime EP0338865B1 (en) | 1988-04-21 | 1989-04-21 | Apparatus for supporting the walls of trenches |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0338865B1 (en) |
DE (2) | DE338865T1 (en) |
GB (1) | GB2217750B (en) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2249114B (en) * | 1990-10-22 | 1994-08-31 | Mabey Hire Co | Trench box for shoring |
CN112746619A (en) * | 2020-12-19 | 2021-05-04 | 徐东新 | Inner supporting structure capable of solving pit bias problem in deep and shallow foundation pit |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
BE755176A (en) * | 1969-11-08 | 1971-02-01 | Krings Jozef | TRENCH SHIELDING DEVICE FOR PIPELINES |
AT317782B (en) * | 1972-08-04 | 1974-09-10 | Krings Josef | Slide shoe for a tensioning device of a trench sheeting device |
CH559828A5 (en) * | 1972-08-04 | 1975-03-14 | Krings Josef | |
DE2702750C3 (en) * | 1977-01-24 | 1979-08-16 | Josef 5138 Heinsberg Krings | Slide shoe for the tensioning device of a Gnfcenverbmivorrichtung |
DE2832321C2 (en) * | 1978-07-22 | 1982-10-14 | Josef Ing.(grad) 5142 Hückelhoven Emunds | Roughly adjustable clamping frame for shoring panels |
-
1988
- 1988-04-21 GB GB8809439A patent/GB2217750B/en not_active Expired - Fee Related
-
1989
- 1989-04-21 EP EP19890304022 patent/EP0338865B1/en not_active Expired - Lifetime
- 1989-04-21 DE DE1989304022 patent/DE338865T1/en active Pending
- 1989-04-21 DE DE1989601806 patent/DE68901806T2/en not_active Expired - Fee Related
Also Published As
Publication number | Publication date |
---|---|
GB2217750A (en) | 1989-11-01 |
EP0338865A1 (en) | 1989-10-25 |
DE68901806D1 (en) | 1992-07-23 |
DE338865T1 (en) | 1990-08-16 |
GB2217750B (en) | 1992-04-08 |
DE68901806T2 (en) | 1993-02-04 |
GB8809439D0 (en) | 1988-05-25 |
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