Method And Apparatus For Lining The Walls Of Excavations

Abstract

A method and apparatus for lining excavations such as pipe trenches including supporting the trench wall faces by means of rigid supporting walls and lining the space between the outer faces of the supporting walls and the associated wall faces of the excavation with a resilient gas envelope.

Description

This invention relates to a method and apparatus for lining the walls of excavations.

The invention relates to a method for the lining of excavations in particular pipe trenches dug out of the ground by supporting their wall faces by means of rigid supporting walls and lining of the space between the outer face of the supporting walls and the associated wall face of the excavation with a resilient material and an apparatus for the carrying out of this method with two supporting walls placed by means of supporting devices against opposite wall faces.

Such excavations have been secured by lining up to a predetermined depth. This lining has been effected up till now by means of cladding-line supporting walls applied by hand, these cladding walls being placed against the supporting wall faces and the space between the supporting wall and the wall face of the excavation are stopped up at the same time with a resilient material, for example, wood-wool, or filled in also with gravel or sand in order to exert a pressure on the whole supporting wall face. This kind of lining takes up a considerable amount of time so that with mechanical digging out of excavations with modern soil digging apparatus, in particular in the digging out of pipe trenches, the working capacity of the machine cannot be completely utilized as the lining takes up a substantially longer time than the digging out itself.

Devices for the supporting of the walls of trenches or the like are indeed known for accelerating this lining work. Thus, an apparatus for the supporting of the walls of trenches during the laying of sewage pipes or the like is known (German Application No. 1634251-1-25) which two sides have supporting walls which together with the necessary reinforcements are connected via adjustable cross struts arranged in their lower and upper part to form a unit inset insertable as a while unit from above into the dug out trench whereby the lower and upper cross struts are associated with adjusting devices operable from above and at the top on the two supporting walls, leads with cross guides for cross guide rods being arranged whereby at least one of the supporting walls is pivotably linked to its upper cross guiding lead and the adjusting device of the lower cross struts are operable separately from those of the upper cross struts. In another known lining apparatus for trenches, excavations or the like each of the two lining plates lying opposite are fixed by means of cross struts is provided with a pressure transmitting foot on which an adjustable cross strut is movable guided.

By means of these known arrangements the placing of the supporting walls is mechanized and thus accelerated; but should thereby a stopping up of the space between the supporting wall and wall face of the excavation be effected subsequently which is not practicable, that is, is not to be carried out at reasonable expence the insertion of these lining devices on excavations in soils in which the walls after the digging out are substantially level (flush soils without course deposits) remains limited.

The invention is based on the problem of providing a method and an apparatus whereby rapidly an absolutely secure support of the wall faces of the excavation even with soils in which the use of the known lining devices is eliminated (now binding soils with course deposits) is possible. According to the invention this is achieved by a method of the above-mentioned type in that the space between the supporting wall and the wall face is filled by means of pressure gas compressed in a resilient envelope.

By means of this method according to the invention it is possible to insert together with the rigid supporting walls or subsequently the resilient envelope in the space between the supporting wall and excavation wall surface and to inflate by means of a suitable source of gas to the required supporting pressure. The resilient envelope is placed against the wall face of the excavation and exerts on the whole face independently of the surface shape a uniform predetermined pressure.

In order to prevent, before the application of the pressure gas, loose soil from crumbling in large quantities, the excavation wall face before the application of the pressure gas can be sprayed with means stabilizing the end face. In order to prevent this crumbling and in order to form at the same time an additional protection for the resilient envelope against damage, for example, due to sharp-edged stones the excavation wall face may also before the introduction of the lining device be covered with a foil and in fact according to the quality of the soil and work conditions additionally for the spraying on of stabilizing means or without this.

An apparatus for the carrying out of this method with supporting walls fixed by means of supporting devices against the wall faces of the excavation is characterised in that on the outer faces of the supporting walls are inflatable resilient envelope is arranged.

Thus the walls may for example, in known manner (German Specification laid open to inspection No. 1123988) consist of frames which however in contradiction to this are filled not with mesh wire but with statically carrying grating grill whereby the size of the squares due to the overbridging effect of the inflatable envelope can be determined not according to the size of the grain of the soil but according to the load capacity of the envelope. Thus a weight and cost saving construction is possible.

In order to render possible a rapid lining and a displacement of the supporting walls corresponding to the lining of a pipe trench the lining devices can be placed next to one another or on one another in a building box manner.

The inflatable resilient envelope is preferably an air mattress-like inflatable cushion so that this cushion may consist of a plurality of chambers connected to one another and separated by cross pieces in order with inflatability to great thickness to achieve a sufficient stability.

In order to cover mechanically the excavation with foil web and also to accelerate this method step or apparatus may be used with two rollers lying opposite which at the free ends of links linked to a guide rod are rotatably mounted which by means of a spring are spread apart against the walls of the trench.

The invention will be described in more detail in the following embodiment with reference to the drawings. In the drawings:

FIG. 1 shows a cross section through a trench with an apparatus according to the invention for the supporting of the walls;

FIG. 2 shows a view of a supporting wall according to the invention; and

FIG. 3 shows diagrammatically an apparatus for the covering of the walls of the trench which foil.

The apparatus shown in FIG. 1 consists of two opposite supporting walls 1 which consist of a frame filled in with a grating 2. The supporting walls 1 are fixed by telescopic struts 3 against the wall faces of the trench whereby the telescopic struts 3 are fixed in the desired relative position to one another by means of a locking device, for example, pins 4 inserted in the corresponding cross bores.

On the corners of the supporting wall 1, supports 1a are provided in which supporting walls placed thereover and adjacent are inserted in order to give coherence. Thus the supporting walls can be connected to one another by means, for example, clamping closures, not shown.

On the outside of the supporting walls 1 air mattress-like envelopes 5 are mounted, for example, by means of belts, not shown, which upon insertion of the supporting walls 1 are not inflated. After the insertion of the supporting walls 1 the envelopes 5 are inflated, for example by means of pressure air to press their outerside against the wall faces of the trench independently of its shape. Due to the mutual supporting by the struts 3 in addition a pressing pressure independent of the inflation pressure is exercised against the two opposite trench walls. The air mattress 5 consists of individual chambers 5a which are separated from one another by cross pieces 5b but are connected pneumatically to one another. It is of advantage to make the air mattress 5 of transparent material for observation of the behavior of the earth walls. Instead of the inflatable envelope there may also be used envelopes which are provided with a permanent resilient filling (for example, foamed rubber). In this case, however, the cross struts are made capable of being spaced apart is the excavation according to the known method.

FIG. 3 shows a cross section of a trench on the side walls of which foil 6 is placed. For the pressing on of the foils against the trench walls an apparatus illustrated is shown which has rollers 7 the surface of which is provided with a waffle-like or indented profile. The rollers 7 may also consist of resilient material and be inflatable like pneumatic tyres. The rollers 7 are rotatably mounted on the face ends of links 10 which are linked at their other ends on a guide rod 9 on a common pivot point 11. The links 10 are tensioned by means of a spring arrangement, for example, a compression spring 8 apart from one another, that is, against the wall faces. The foil 6 is rolled along the walls of the trench and by pressure through the apparatus according to FIG. 3 is fixed on the wall such that it adheres until insertion of the lining apparatus according to FIG. 1.

With very loose soil the wall faces of the trench before the application of the foil may be sprayed with a stabilizing means, for example, cement, bitumen emulsion or the like. This support may under certain circumstances suffice so that the covering with foil is not necessary. By this prehandling of the walls of the trench with spray means and/or foil the danger of the subsidence of trench walls after removal of the lining is reduced as a bonding of the soil grains with the spray means and as the case may be the foil by the foil.

Claims

What we claim is:

1. A method for lining generally planar side walls of an open trench excavated within a ground surface for supporting the side walls of the trench comprising the steps of:

spraying the open trench side walls with a stabilizing means;

inserting generally planar supporting walls carrying inflatable envelopes, upon outside surfaces thereof, within the open trench in contiguous but spaced relation to the generally planar side walls of the open trench;

fixing the supporting walls in a stationary spaced posture within the open trench by adjustment of struts extending between inside surfaces of the supporting walls; and

inflating the inflatable envelopes carried upon the outside surfaces of the supporting walls to mutually cross-react through the supporting walls and the struts against opposing side walls of the open trench to firmly stabilize the side walls of the open trench.

2. The method for lining and supporting side walls of an open trench as defined in claim 1 and further, subsequent to said step of spraying the side walls of the open trench, the step of:

applying a foil to each of the side walls of the open trench by pressing a foil against each of the side walls with a waffle-like profile to adhere the foil to the open trench side walls.