GB2381818A

GB2381818A - Drill assisted penetration of sheet piles

Info

Publication number: GB2381818A
Application number: GB0126580A
Authority: GB
Inventors: Ian Mcintyre
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-11-06
Filing date: 2001-11-06
Publication date: 2003-05-14
Also published as: GB0126580D0

Abstract

A sheet pile includes conduits (2) at intervals along the pile which allow drills (3) to drill out earth below the sheet pile. When the piles are driven further, earth beneath the piles is sheared and falls into holes (5) produced by the drills (3), thus reducing the resistence to driving. The sheet piles may also be provided with strengthened toes (4) to assist penetration.

Description

SHEET PILE SYSTEM FOR PENETRATING HARD GROUND This invention relates to a sheet pile system for penetrating hard ground.

Sheet piles are commonly formed from sheets of steel, timber, concrete, or any other convenient material. These sheets of material take many different forms, including rectangular slabs of concrete or sheets of steel formed into complex shapes to improve performance. The individual sheet piles are driven into the ground and commonly link together at their sides to form a continuous wall. The completed wall is capable of retaining soil or water or other materials. The completed wall is also commonly used to support vertical loads.

The strength of sheet pile walls is sometimes improved by tying the wall back to an anchor.

Sheet pile walling is a form of construction widely used in construction and it is unnecessary to provide diagrams herewith to illustrate the various forms of sheet pile wall system in use now or in the past. It is also unnecessary to describe the various forms of hammer, vibration or other equipment commonly used to drive the sheet piles into the ground.

Sheet piling can be driven into the ground until the density or strength of the ground becomes so great that further penetration is prevented. Further depth of penetration can then be achieved by increasing the driving force applied to the sheet pile. However, at some point, the increased driving force will become so great that the sheet pile itself will be damaged, without achieving further penetration. This can frequently occur where the bottom of the sheet pile (the pile toe) penetrates to the level of a layer of hard ground or rock. It can also occur where the depth of penetration into soil is great.

The depth to which sheet piles can penetrate has previously been increased by applying a water jet at the level of the bottom of the sheet piles to loosen soil. Another system has used explosives to break up rock layers, thereby easing the penetration of the sheet piles. Other methods have been used including the addition of hardened toes to the piles.

The present invention is unique in providing a simple and effective method for penetrating hard ground with sheet piles by drilling or otherwise forming a cavity ahead of the pile toe. By using this method the gross ground disturbance and weakening caused by water jetting or blasting is avoided.

Also the security problems associated with explosives are avoided.

The present invention can be applied to sheet pile walls made from any of the materials commonly used for sheet piling work.

The essential feature of this unique system is that conduits are provided within the sheet pile wall at intervals along its length. The conduits extend from the tops of the sheet piles down to their toes. A small diameter drill may then be introduced to remove the ground from within each conduit or as many as desired at each stage of the work. Drilling is continued to form a cavity beyond the toes of the sheet piles. The cavity may also be formed by any other convenient method, using the conduits to gain access to the level of the pile toes. The piles are then re-driven and the ground ahead of the sheet pile toes is sheared and falls into the cavity ahead of the sheet pite toe. Breaking the ground in this shearing manner is far easier than attempting to crush the ground in direct bearing. The process is then repeated until the desired penetration is achieved.

The advance knowledge that sheet piles can be driven to the required depth will be of great benefit. There are many situations where a given depth of penetration is required to develop the necessary resistance to lateral movement. In these situations, adequate penetration into the ground is necessary. If hard ground prevents adequate penetration the sheet pile wall cannot function as designed.

The invention can conveniently be incorporated into sheet piles prior to driving, in the form of the conduits. Even if no drilling proves to be required, use of the invention ensures that the piles can be used with the confidence that the necessary penetration can be achieved.

The procedure of drilling a small pilot hole prior to forming a hole of the desired size is used in many applications. Adaptation and development of this concept into a technique applicable to sheet piling, as described herein, is new.

The present invention offers the following advantages over previously available methods of driving sheet piles : (i) The system is easy to incorporate into any type of sheet pile wall, made from any type of material.

(ii) Gross disturbance of the existing ground is avoided, so that its properties remain as shown by a site investigation.

(iii) It offers the certainty that sheet piles can be driven to the required depth.

(iv) It avoids the security problems associated with use of explosives.

(v) It is simple in concept and operation.

(vi) The conduits may be arranged so that the amount of drilling required is minimized.

A specific embodiement of the invention will now be described by way of nonlimiting example with reference to the accompanying drawings in which:

Figure 1 shows a plan on a short section of steel sheet pile wall. The plan is not intended to represent any of the proprietary shapes of sheet piling in use, as the current invention can be incorporated into sheet piles of any cross-sectional shape. Details of the connections between adjacent piles 1 (the pile clutches) have been omitted to simplify the diagram. Possible locations of the clutches are shown. However, the clutches can be located at any convenient position.

Possible locations of the conduits 2 are shown. These can also be located at any convenient points.

Figure 2 shows an elevation of the sheet pile wall with the drill 3 in the process of forming a hote below the toes 4 of the sheet piles.

Previously drilled holes 5 can be seen.

The drill may be operated by turning a shaft 6 above the tops 7 of the sheet piles.

A sheet pile element 8 is the length of sheet pile wall between the clutches connecting the element to adjacent elements.

The diameter and spacing of the conduits may be varied as required to achieve the most efficient arrangement.

Hardened shoes may be incorporated in the pile toes or in the lower ends of the conduits in order to improve their resistance to damage during driving.

Holes may be formed below the sheet pile toes by drilling, as described above, or by any other convenient method.

The shapes of individual sheet piles and details of pile clutches may be varied as required to suit the materials and style of the sheet pile wall in which the current invention is incorporated.

Claims

CLAIMS 1. A sheet pile system for penetrating hard ground wherein a conduit is incorporated into the sheet pile wall at suitable intervals, allowing holes to be formed below the toes of the sheet piles to assist penetration of the piles into dense or hard ground.
2. A sheet pile system as claimed in claim 1 wherein the conduit is incorporated in additional pile elements linked in to the normal sheet pile sections by use of suitable clutches.
3. A sheet pile system as claimed in claim 1 or claim 2 wherein the ends of the sheet piles and/or drill conduits are provided with strengthened toes to assist pile penetration.
4. A sheet pile system as claimed in any preceding claim wherein the sheet piles are made from steel, concrete, timber, plastic or any other convenient material.
5. A sheet pile system as claimed in claim 1 and substantially as hereinbefore described with reference to the accompanying drawings.
6. A sheet pile system comprising individual sheet pile elements inked together to form a wall and incorporating conduits substantially as herein described and as claimed in any of the preceding claims.