HK1160672B - Retaining wall - Google Patents

Description

Protective wall

Technical Field

The present invention relates to a retaining wall and to a method of constructing the same.

Background

A retaining wall is a structure that prevents soil or rock from reaching a building, structure or area. The retaining wall prevents downward landslide movement or erosion and provides support for vertical or near vertical gradient (grade) changes. Structures, cofferdams and bulkheads that block water are also considered retaining walls.

One type of conventional retaining wall is formed from sheet piling. Sheet pile walls are made of steel, vinyl, fiberglass, reinforced concrete or plastic sheet piles driven into the ground. Sheet pile walls are typically constructed by driving steel sheets into the ground to allow excavation or filling on one side of the wall. They are considered most economical in situations where it is desirable to maintain high earth pressures of soft soils. Sheet piles, however, can be expensive and are less suitable for difficult driving conditions, especially where boulders or irregular rock surfaces occur in the ground.

To meet difficult driving conditions, sheet piles are often designed for improved drivability rather than to suit the structural requirements of the retaining wall to be formed. This therefore results in inefficient and not cost effective use of the sheet pile.

Disclosure of Invention

According to the present invention there is provided a retaining wall for retaining material on a side thereof, comprising: a plurality of upwardly projecting primary sheet piles spaced apart from each other and having first structural characteristics including at least one of weight, size, strength and depth to be installed in the support body; and one or more intermediate material panels arranged so as to span the gap between the pair of primary sheet piles and retain at least a portion of the retained matter, wherein the one or more intermediate panels have a second structural characteristic different from the first structural characteristic.

Embodiments of the present invention thus utilise the use of (primary) sheet piles, which are designed for primary purposes, such as drivability, strength or minimum depth required for overall wall stability, to be offset with respect to the structural characteristics of a panel disposed between a pair of (primary) sheet piles. In this way, sheet piles may provide most of the structural capacity for the vertical spanning function of the retaining wall. Thus, the intermediate panel does not have to have the same structural properties as the main sheet pile. For example, they do not have to be driven as far into the support ground (supporting ground) as the primary sheet piles, and may have less weight, size, cost, and/or strength. Thus, cost savings can be achieved in terms of intermediate panels, and such walls may be a more affordable product.

With the additional structural capacity of the sheet pile, for example, embodiments are suitable for forming retaining walls in situations where installation conditions require sections heavier than structurally required for retaining wall function.

The one or more intermediate panels may apply pressure to or connect to the pair of primary sheet piles in order to provide improved lateral stability. Such a connection may also be adapted so as to provide a watertight seal between the intermediate panel and the primary sheet pile.

An embodiment may further comprise a stop or stop adapted to limit the vertical movement of the one or more intermediate panels in a predetermined position, thereby assisting the correct positioning of the intermediate panels when constructing the retaining wall. The stopper/stopper may be provided separately from or fixed to the main board pile or the intermediate panel.

Drawings

Examples of the invention will now be described in more detail with reference to the accompanying drawings, in which:

FIG. 1 is a front cross-sectional view of a retaining wall according to an embodiment of the invention, wherein the cross-section is along the line Y-Y in FIG. 2; and

fig. 2 is a cross-sectional view taken along line X-X in fig. 1.

Detailed Description

Referring to fig. 1 and 2, a retaining wall 10 for retaining a substance 11 such as soil and/or water on its side is shown. The retaining wall 10 comprises a combination of primary sheet piles 12 spaced apart from one another and intermediate panels 14 spanning the gap between the pairs of primary sheet piles 12.

Primary structural support for the wall is provided by the primary sheet pile 12 driven into the surface 16 of the support 18 (in other words, the supporting ground) to a depth "D1". The intermediate panel 14 is driven into the support to a lesser depth "D2" (i.e., D1 > D2) and retains at least a portion of the retained material 11. In other words, the bottom of the one or more intermediate panels is vertically offset with respect to the bottom of the primary sheet pile pair. However, it should be understood that "vertically offset" in the context of the present invention should be understood to mean intentionally and intentionally offset vertically as opposed to offset by a small amount caused by construction tolerances when attempting installations of substantially equal depths. That is, "vertically offset" should be understood to exclude the following: the sheet piles should be installed at substantially equal depths in the support body but slightly vertically offset from each other due to construction difficulties and/or tolerances. For example, in an embodiment of the invention, the bottom of the one or more intermediate panels is vertically offset with respect to the bottom of the pair of primary sheet piles, for example by more than 10 cm, preferably more than 50 cm, more preferably more than 1 meter.

The primary sheet piles 12 serve as primary members to provide structural restraint to bending and shearing in the walls, while the intermediate panels hold matter 11 such as soil and/or water by spanning horizontally between the primary sheet pile pairs 12.

Because the intermediate panels 14 only require primary support structure suitable for holding matter and not providing walls, the intermediate panels 14 may have less weight, size, and/or strength than the primary sheet piles 12 and are typically driven less far into support than the primary sheet piles. In the illustrated embodiment, the intermediate panels 14 have a minimum length required to support retained material or meet other requirements such as water cut-off by spanning horizontally between the main panels.

The intermediate panel 14 may be formed of any suitable material including, for example, plastic, reinforced plastic, wood, cloth, concrete, reinforced concrete, and metal. The intermediate panel 14 may also be formed of the same material as the primary sheet pile 12, and in such a case, the intermediate panel 14 may also be a sheet pile 12.

For example, although the intermediate panels 14 are shown as having smaller dimensions than the primary sheet piles 12, they may have the same dimensions as the primary sheet piles but have different weights and/or strengths. Alternatively, the intermediate panels 14 may be the same as the main pile structure but differ in that they are shorter and designed to span horizontally between the main piles without relying on any vertical bending capability of the intermediate portions. Furthermore, although fig. 1 and 2 illustrate the tops of the primary sheet piles 12 and the intermediate panels 14 being flush with each other, they need not be flush with each other in other embodiments.

In the illustrated embodiment, an intermediate panel 14 is connected to the primary sheet pile 12 so as to form a seal that prevents or limits the passage of water through the retaining wall. Further, the intermediate panel 14 is reinforced by structural members (not shown) as needed.

The retaining wall 10 is constructed by arranging a plurality of primary sheet piles 12 spaced apart from each other and projecting downwardly into the supporting ground. One or more intermediate panels 14 are arranged so as to span the gap between the pair of primary sheet piles 12 and retain at least a portion of the retained substance 11. By doing so, the intermediate panels 14 are also arranged to project downwardly into the supporting ground to a lesser extent than the primary sheet pile pairs.

The intermediate panel 14 may be driven or pushed into place separately or may be secured to the primary sheet pile 12 and installed with the primary sheet pile 12.

To aid in alignment, one embodiment may be installed with temporary long secondary panels that may: (a) consisting of two parts detachably connected together to form a temporarily longer panel which is later partly withdrawn and the top detached from the bottom; or (b) include a longer panel that is then withdrawn completely and replaced with a shorter/smaller intermediate panel.

Stops or detent devices may be used on the primary sheet piles, intermediate panels and/or supports to limit vertical movement of the intermediate panels to the required level and to assist in their positional correction.

Embodiments may be particularly suitable for applications such as widening of motorways over embankments, where relatively large and/or long sheet piles may be required to maintain a low ground height. In such cases, sheet piles are typically of a size for drivability rather than structural requirements for retaining walls. Thus, for example, sheet piles have considerable additional structural capacity to trade off (trade off) the structural characteristics of the intermediate panel 14, which enables cost savings to be achieved.

In case a water cut-off function is required, this can be achieved in a number of ways, for example by:

(i) the intermediate portion is driven or pressed deeper to achieve truncation, increasing the cross-sectional size for drivability as required and/or assisting driving by suitable methods such as pre-drilling or jetting.

(ii) The dado is installed along a line of pre-installed low permeability block barriers formed by any method, such as a trench wall (digging a trench and backfilling with cement bentonite mud to form a water block), a stabilized soil wall or a vibrating wall (vibwall) (forming a water block by driving a large steel i-beam while injecting bentonite mud.

(iii) An intermediate section having the same thickness as the lightweight intermediate section ("mandrel") to which the cement pipe is attached is driven or pressed to the required cut-off depth and cement is injected as the mandrel is withdrawn, and then a thin intermediate section is driven to the normal depth of the intermediate section according to an embodiment.

(iv) As in (iii) but drives the thin middle section to full depth (i.e. the same depth as the primary sheet pile).

(v) Such as (iii) or (iv) but grouted with cement.

A similar technique using a mandrel as described above, with or without a grout tube and grout, can be used to advance the light intermediate section to a depth beyond that to which the intermediate section can be advanced by normal methods, including by pre-drilling or jet assisted driving.

Although specific embodiments have been described herein for purposes of illustration, various modifications will be apparent to those skilled in the art and may be made without departing from the scope of the invention.

For example, embodiments may be implemented in cantilever or anchor retaining wall applications, and the intermediate panels may have an arched form that operates in tension or compression to retain the substance.

Further, the intermediate panel may have a width greater than a gap between a pair of spaced apart sheet piles. In such embodiments, the panels may not be connected to the sheet piles but instead simply be placed at the back/front so that they exert pressure on the sides of the sheet piles.

Claims (10)

1. A retaining wall for retaining matter on a side thereof, comprising:

a plurality of upwardly projecting primary structural members spaced apart from one another and having a first structural characteristic comprising at least one of weight, size, strength, and depth to be installed in the support body; and

one or more intermediate panels of material arranged so as to horizontally span the gap between pairs of primary structural members and thereby retain a retained matter between the primary structural members,

wherein the primary structural member is a sheet pile and the one or more intermediate panels project downwardly into the support body to a lesser extent than the primary structural member and have second structural characteristics different from the first structural characteristics such that the sheet pile is adapted to provide primary structural constraints for bending and shearing in the wall.

2. A retaining wall as claimed in claim 1, wherein the one or more intermediate panels of material comprise at least one of: auxiliary sheet piles; a flexible sheet adapted to be driven into the support to a lesser extent than the primary structural member; and a panel of rigid material.

3. A retaining wall as claimed in any preceding claim, wherein the one or more intermediate panels are connected to the pair of primary structural members.

4. A retaining wall as claimed in any preceding claim, wherein the one or more intermediate panels comprise at least two panels of material connected to one another.

5. A retaining wall as claimed in any preceding claim, further comprising a stop adapted to limit vertical movement of the one or more intermediate panels at a predetermined position.

6. A method of constructing a retaining wall for retaining material on a side thereof, wherein the method comprises the steps of:

arranging a plurality of primary structural members such that the primary structural members are spaced apart from each other and project downwardly into the support body, the primary structural members having a first structural characteristic comprising at least one of weight, size, strength, and depth to be installed in the support body; and

arranging one or more intermediate panels so as to project downwardly into the support to a lesser extent than the primary structural members and to horizontally span the gap between pairs of primary structural members and thereby retain the retained matter between the primary structural members; and

wherein the main structural member is a sheet pile, and

wherein the one or more intermediate panels have second structural characteristics different from the first structural characteristics such that the sheet pile is adapted to provide primary structural constraints for bending and shearing in the wall.

7. A method according to claim 6, wherein the one or more intermediate panels are arranged to project downwardly into the support to a lesser extent than the pair of main structural members, such that the bottoms of the one or more intermediate panels are vertically offset relative to the bottoms of the pair of main structural members.

8. The method of claim 6 or 7, further comprising the step of connecting the one or more intermediate panels to the pair of primary structural members.

9. The method of claim 6, 7 or 8, wherein the retaining wall is installed along a line of pre-installed low permeability shut-off barriers.

10. The method of any one of claims 6 to 9, wherein the step of arranging the one or more intermediate panels comprises:

driving a mandrel, to which a cement pipe is attached, into the support body;

withdrawing the mandrel from the support; and

inserting an intermediate portion into a hole left in the support body after withdrawing the mandrel.