GB2142963A - Concrete blocks - Google Patents

Abstract

A statically interlocking concrete armour unit essentially placed in horizontal rows on a slope, units in each row being lowered directly into position between and half a unit length further up the slope from units in the previously placed row such that each unit is in contact end on end with units in alternate rows via parallel front (seaward) and rear end faces 10 & 11 for restraint against rotation and movement up or down the slope. Critical restraint against movement away from the face of the slope is effected by lateral projections 12 adapted to cause the rear portion of each unit to be partly overlain by the front portion of units in the following row. This contact with adjacent units also provides restaint against lateral movement. <IMAGE>

Description

SPECIFICATION Statically interlocking concrete armour unit This invention relates to the field of civil engineering the specific branch being coastal, marine or dock and harbour engineering.

Armour is used in coastal areas to protect slope formations against erosion from wave action on breakwaters and seawalls etc. Rock was the first material to be used but its restricted availability and unsuitability for certain applications led first to the use of massive concrete blocks and later to the development of regular and irregular shaped units.

Irregular units form a layer with a high voids ratio for effective dissipation of wave energy. They also have a partial interlocking capability but still have to be of sufficient size to resist uplift by their self weight and are susceptible to movement which causes post construction damage.

Regular shaped units can be either partially or fully (statically) interlocking or non-interlocking. Noninterlocking types, unless of considerable size to prevent disturbance, are suitable only for shallow slopes where disturbing forces are low.

Interlocking units presently in use are disadvantaged by requiring accurate and complicated slope formation and some manouvering into place. Also the shape of these units offers little dissipation of wave energy or resistance to 'run-up' making them unsuitable for use on breakwaters.

This invention provides a statically interlocking concrete armour unit comprising parallel front (seaward) and rear end faces and lateral projections, the units essentially being placed in horizontal rows, each unit of a row located between two units of the previously placed row and half a unit length higher on the slope such that units in alternate rows contact end on end for restraint against rotation the lateral projections adapted to cause the forward parts of units in a row to partly overlay the rearward parts of units in the previously placed row thereby providing them with restraint against movement away from the face of the slope.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawing in which: Figure 1 shows the unit in perspective and its relationship to adjacent units.

Figure 2 shows in perspective the appearance of a finished slope.

Referring to Figure 1 the unit comprises front (seaward) and rear end faces 10 and 11, lateral proiections 12, recesses 13 and sloping side faces 14 on both sides, an extended front face 15 and a horizontal top surface 16.

Referring to Figure 2 each unit is lowered directly into position on the slope between adjacent units of the previously placed row so that the outward sloping faces of the lateral projections at the front end of the unit contact the sloping side faces at the rear ends of adjacent units imparting restraint against movement away from the face of the slope and creating mutual restraint lateral movement. This process of restraint is repeated as each row of units is placed.

At the same time the unit is placed so that its front face contacts the rear face of the unit below. This process repeats when the next but one row is placed.

Restraint is thereby provided to each unit against movement up or down the slope and the parallel nature of the contact faces provides restraint against rotation.

The recesses 13 give the armour system a high voids ratio and the extended front face 15 causes wave deflection and reduces 'run-up'. These two features are intended to make the unit suitable for use on breakwaters where the static interlock affords steeper slopes and removes reliance on the selfweight of units.

The horizontal top surface 16 provides a stepped feature to the finished slope permitting access for construction and amenity purposes.

1. A statically interlocking concrete armour unit comprising parallel front (seaward) and rear end faces and lateral projections, the units essentially being placed in horizontal rows, each unit of a row located between two units of the previously placed row and half a unit length higher on the slope such that alternate rows contact end on end for restraint against rotation and the lateral projections adapted to cause the forward parts of units to impart restraint to the rearward parts of units in the previously placed row against movement away from the face of the slope and create mutual restraint against lateral movement.

2. A unit as claimed in Claim 1 adapted to permit placement by lowering directly into position.

3. A unit as claimed in Claim 1 or Claim 2 wherein the self weight of the unit is supported in part by a unit or units in the previously placed row.

4. A unit as claimed in any preceding claim wherein the self weight of the unit is supported in part by the unit immediately below on the slope.

5. A unit as claimed in any preceding claim wherein the front contact face is extended to provide the capacity for wave deflection and prevention of 'run-up'.

6. A unit as claimed in any preceding claim shaped to include recesses or voids to increase the voids ratio of the armour system.

7. A unit as claimed in any preceding claim wherein the front and rear faces are adapted to provide extra restraint against lateral movement.

8. A unit as claimed in any preceding claim provided with a top surface either wholly or in part horizontal or near horizontal for ease of access during or after construction.

9. A unit substantially as described herein with reference to Figures 1 and 2 of the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (10)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Statically interlocking concrete armour unit This invention relates to the field of civil engineering the specific branch being coastal, marine or dock and harbour engineering. Armour is used in coastal areas to protect slope formations against erosion from wave action on breakwaters and seawalls etc. Rock was the first material to be used but its restricted availability and unsuitability for certain applications led first to the use of massive concrete blocks and later to the development of regular and irregular shaped units. Irregular units form a layer with a high voids ratio for effective dissipation of wave energy. They also have a partial interlocking capability but still have to be of sufficient size to resist uplift by their self weight and are susceptible to movement which causes post construction damage. Regular shaped units can be either partially or fully (statically) interlocking or non-interlocking. Noninterlocking types, unless of considerable size to prevent disturbance, are suitable only for shallow slopes where disturbing forces are low. Interlocking units presently in use are disadvantaged by requiring accurate and complicated slope formation and some manouvering into place. Also the shape of these units offers little dissipation of wave energy or resistance to 'run-up' making them unsuitable for use on breakwaters. This invention provides a statically interlocking concrete armour unit comprising parallel front (seaward) and rear end faces and lateral projections, the units essentially being placed in horizontal rows, each unit of a row located between two units of the previously placed row and half a unit length higher on the slope such that units in alternate rows contact end on end for restraint against rotation the lateral projections adapted to cause the forward parts of units in a row to partly overlay the rearward parts of units in the previously placed row thereby providing them with restraint against movement away from the face of the slope. A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawing in which: Figure 1 shows the unit in perspective and its relationship to adjacent units. Figure 2 shows in perspective the appearance of a finished slope. Referring to Figure 1 the unit comprises front (seaward) and rear end faces 10 and 11, lateral proiections 12, recesses 13 and sloping side faces 14 on both sides, an extended front face 15 and a horizontal top surface 16. Referring to Figure 2 each unit is lowered directly into position on the slope between adjacent units of the previously placed row so that the outward sloping faces of the lateral projections at the front end of the unit contact the sloping side faces at the rear ends of adjacent units imparting restraint against movement away from the face of the slope and creating mutual restraint lateral movement. This process of restraint is repeated as each row of units is placed. At the same time the unit is placed so that its front face contacts the rear face of the unit below. This process repeats when the next but one row is placed. Restraint is thereby provided to each unit against movement up or down the slope and the parallel nature of the contact faces provides restraint against rotation. The recesses 13 give the armour system a high voids ratio and the extended front face 15 causes wave deflection and reduces 'run-up'. These two features are intended to make the unit suitable for use on breakwaters where the static interlock affords steeper slopes and removes reliance on the selfweight of units. The horizontal top surface 16 provides a stepped feature to the finished slope permitting access for construction and amenity purposes. CLAIMS

1. A statically interlocking concrete armour unit comprising parallel front (seaward) and rear end faces and lateral projections, the units essentially being placed in horizontal rows, each unit of a row located between two units of the previously placed row and half a unit length higher on the slope such that alternate rows contact end on end for restraint against rotation and the lateral projections adapted to cause the forward parts of units to impart restraint to the rearward parts of units in the previously placed row against movement away from the face of the slope and create mutual restraint against lateral movement.

2. A unit as claimed in Claim 1 adapted to permit placement by lowering directly into position.

3. A unit as claimed in Claim 1 or Claim 2 wherein the self weight of the unit is supported in part by a unit or units in the previously placed row.

4. A unit as claimed in any preceding claim wherein the self weight of the unit is supported in part by the unit immediately below on the slope.

5. A unit as claimed in any preceding claim wherein the front contact face is extended to provide the capacity for wave deflection and prevention of 'run-up'.

6. A unit as claimed in any preceding claim shaped to include recesses or voids to increase the voids ratio of the armour system.

7. A unit as claimed in any preceding claim wherein the front and rear faces are adapted to provide extra restraint against lateral movement.

8. A unit as claimed in any preceding claim provided with a top surface either wholly or in part horizontal or near horizontal for ease of access during or after construction.

9. A unit substantially as described herein with reference to Figures 1 and 2 of the accompanying drawing.

10. A unit as claimed in any preceding claim wherein the lateral projection occurs on one side