GB2280215A

GB2280215A - Reinforced concrete retaining wall structure

Info

Publication number: GB2280215A
Application number: GB9414376A
Authority: GB
Inventors: Muelas Medrano Santiago
Original assignee: Fospas S L
Current assignee: Fospas S L
Priority date: 1993-07-23
Filing date: 1994-07-11
Publication date: 1995-01-25
Also published as: ES2091704B1; ITMI941440A1; IT1270083B; FR2708014A1; GB9414376D0; ITMI941440A0; ES2091704A2; DE4423890A1; ES2091704R

Description

2280215 Title Reinforced Concrete Retaining Wall Structure Lhe present

invention relates to a reinforced retaining wall structure, more especially using precast concrete C) wall technology.

At present there is an increase in the use of precast ground retaining wall structures, sometimes referred to as bridge abutment systems. The present invention more especially concerns systemised industrialisation of these structures and, in general, manufacture of component parts -o the place where the wall at a location different t structure is finally to be built.

The systems used at present can be divided into two main groups. The first refers to that which is often called 112round reinforcement", wherein elements are mixed or CD inserted into the earth, thereby to impart artificial cohesion to the soil w.hich permits it to stand with a vertical or almost vertical face. These elements are bh a surface eler--,ent, sometimes usually reinforced will called the shell or skin, that prevents the mass of the system from surface crumbling.. There are many variations of this technique, alepending on the type and characteristics of the inserted elements, which can be metal or plastic or textiles, for example, sometimes in the form of strips or bands.

ften usec- is the more classic, which The second system ol employs counterfort or abut.ment walls. In this systeri, a fac-i,",c,,, wall is manufactured and joined before or after erection of abutments. The unit is placed on the job site by means of cranes and shoring and then the foundation footing concrete is poured. Once the concrete footing has set, the extrados of the wall can be filled in. There are many variations of this system, depending on the type of counterfort, continuous with or separated from the facing panel and depending if the Ifacing wall and counterfort are manufactured at the same time or not. On occasions, they are Joined afterwards and, in some cases, the footing is cast, only affecting the counterforts, and the facing wall, consisting of one or several parts, is sited between the counterforts. As stated, the number of variations is enormous and it is impossible to give even a summarised description here of all the systems currently in use. For low walls, for example, it is standard tice to cast the panel and counterfort in the factory, pract together with the footing.

Within the existing systems, some are based on anchoring or supporting the facing wall to areas existing behind the 117'illin-. For example, concrete facinIg walls, generally C:) I made in situ, are frequently anchored to extrados rock areas. There exist special techniques that perforate the rock, introduce a bolt and fasten or anchor the facing wall to the rock. Normaljy, this is not done with precast walls, although it is evident that the precast walls could be anchored. Another known system involves utilisation of anchors by means of introducing dead masses in the form of square blocks or plates in the extrados filler in a metal sheetpile wall structure.

The conventional system havin,,7; a facing wall uses counterforts cast to a footing, which results in the 1 -acing wall and counterfort working, structuralLy- CD speaking, as a cantilever. This manner of working is C> C:) very inefficient and has very high material cost's.

The present -invention primarily consists of having the facing wall and counterfort assembly working together W_ embedded in the footing, but also fastened at some intermediate point. ground reinforcement ground reinforcement exclusively concerns which have slight but the invention provides a solution to this problem.

-ion does not require The invent and has nothing to do with known techniques. The invention facing walls of concrete material, definite deformation capacity, but The invention is best briefly described with reference to the accompanying drawings, wherein Figure 1 represents a -op cross-section of the proposed wall and Figure 2 is a t view of a section of this wall. From, the relative sizes and dimensions illustrated, the very important net savings obtained in materials can be appreciated. Figure 3 shows the building process employed in the present invention, illustrating the dimensions of the footing, to scale, for a typical wall height chosen as an example. The footing C) has been sized for half of the total height of the wall.

In this way, the construction process can be started in situ in the same way as when using. any other conventional -Pacing wall, with the particularity of obt C) precast J kainincr a very substantial decrease in the footinn.'s dimensions.

Figure 4 shows a wall, with conventional footing, for the same height, and also illustrates the cantilever reinforcement that the wall must contain. By comparison, Fi,ure 5 shows the footing employed in this invention, for C) Oic By exam-ining, Fi.-.:,=e 3, it the sarne safety coeiff- _Jent. -he extrados behinl filled can be seen that 1. 1 the wall is -i with th.e footing up to hall.f of the height of the wall, w-hout surpassing any calculated safety coefficient.

i 1.

Once half of the wall height has been reached with the filler, a dead mass or reinforced concrete block (precast or made in situ) is placed in the indicated position, in -icient distance from the active other words, at a suf L buoyancy wedge adjacent to the footing to which a S t galvanized steel bol (having sufficient diameter required for the calculated conditions) is attached. This bolt acts as a "tension bar" and serves as the wall anchor. Then, backfilling and compacting of the dead mass towards the facing wall is continued, to avoid the movement of the dead mass. Depending on how the second stage of backfilling is carried out, the wall assembly will behave correctly. It is possible that the facing wall could move slighttly, without this representing any safety loss, and only in the case that t'ne backfilling is not done sufficiently carefully. Fiogure 6 shows a detail of the syster. used to anchor the bolt to the panel, which allows -ension aljust subsequent 11 Lment. Once the wall is finished, the tension adjusted and its stability checked, fii1in,=-- in is completed to cover the work, so that no remains of the process can be seen.

The invention as described in an exe p 1 - - m lary manner represents a very great improvement in the cost of retainin,- walls. The levell of savings for higher walls, C of six metres, for example, is approximately fifty percent.

A particular improvement obtainable with this invention consists of exact control of the tension of the tension bar. By carrying out this cr)ntrol-, any possible movement that could have negative effects, primarily from an aesthetic point of view, disappears.

T 1he tension of the bar can be controlled by means of a dynamometric torque wrench, which sets the grip torque.

Lhe working tension of the bolt can be set, based on the torque, to coincide with the calculated tension. In other words, this further feature of the invention means that, for the first time, earth retainment structures and bridge abutments can be built with an almost exact knowledge of the working tension of the structure. it is general knowledge that the soil thrust can be calculated using semi-empirical methods, generally based on out-dated equations, which do not take building processes into account, such as compacting or the true characteristics of the filling. With the invention as above exemplified, manner of operation of the structure can be controlled to a greater extent, which represents a very important advance in the field of retainment engineering.

For a better understanding of the different drawings accompanying this specification, a more complete description now follows:-

Fig,ure 1 represents a cross-section of the facing wall C= 1 wherein the footine 2 in which the wall is embedded can be seen, as well as the bolt 3 -he dead mass that acts as a tension bar and 4 of reinforced concrete; Figure 2 is a top view of a wall section 1 in which the erent tension bars that control the facing difl cj wall can be seen; Fi-ure- 3 shows the building process for the wall 1 - 6 structure, including the facing wall 1, the corresponding footing 2, the extrados filling C uo to half the wall height, tne dead mass 4 and the remaining filler 6 which prevents movement ol the dead mass 4; Figure 4 shows a wall 7 with conventional footing 8 wherein a counterfort, which acts as a cantilever, can be seen, and which the wall structure must essentially contain; Figure 9 shows the difference in footing size between 1 J.

a wall built in accordance with the present 11 L invention and that of FiEure 4, and in particular the decrease in the size of the counterfort that is now doubly supported by the footing and the anchoring; Figure 5 shows the joining of W - J.

anchoring, includin., washer 10 and the nut the work cup 12, which once the work tension 4- k.he counterfort and the bolt 3, the distribution 11 that remain inside of is filled with cement has been regulated and stabilisation controlled, and it will be;2riven the same finish as the rest of the surface of the facing wall.

Various modifications of the above-described and illustrated wall structure are Dossible within the scope of the invention defined in the followinz- claims.

C> 7

Claims

Claims

CilF 1. A reinforced concrete retaining wall structure having controlled tension, comprising a facing wall and one or more anchoring masses in the wall filler behind the facing wall, joined to the facing wall by means of one or more coupling elements, the arrangement being such that the immobility of the anchoring mass or masses ensures the stability of the facing wall, without requirement for earth reinforcement.
2. A structure according to claim 1, wherein the anchoring mass or masses are of solid concrete, precast or CD cast in situ.
3. A structure in accordance with claim 1 or claim 2, having a support footing in the base, predesigned for a C height lower than the height of the facing wall, which allows a first-stac-e exItrados filling up to the level of C.

the one or more anchoring masses.
4. A structure in accordance with any of the preceding claims, wherein the or each coupling element between the facinS wall and the anchoring mass or masses is or are - le ol. -alvanized steel, which coupling or coupling aa W C) r elements can be tightened, with consequential movement of C) the anchoring mass or masses, as necessary, to control the earth's passive thrust.
5. A structure in accordance with any of the preceding claims, wherein the torque control and consequently the - 8 tension of the coupling elements is verified by means of a u cj dynamonetric torque wrench or llike device.
6. A claims, structure in accordance with any of the preceding employing one or more non-ricz;:,,id coupling elements such as cables or the like, tension being controlled by torque devices.
7. A reinforced concrete retaining wall structure substantially as hereinbefore described with reference to the accompanying drawings.

CI