US2654434A - Apparatus for drying excavations - Google Patents

Description

Oct. 6, 1953 J. T. CULLETON APPARATUS FOR DRYING EXCAVATIONS 2 Sheets-Sheet 2 Filed June 10, 1950 INVENTOR. T. CULLETON fifib JOHN ATTORNEY Oct. 6, 1953 J. T. CULLETON APPARATUS FOR DRYING EXCAVATIONS 2 Sheets-Sheet 1 Filed June 10. 1950 I INVENTOR. JOHN T- CULL E TON 3W ATTORNEY Patented Oct. 6, 1953 UNITED STATES APPARATUS FOR DRYING EXCAVATIONS John T. Culleton, Hayward, Calif., assignor to Pacific Pumping Company, Oakland, Calif., a corporation of California Application June 10, 1950, Serial No. 167,439

4 Claims.

This invention relates to an apparatus for keeping seepage water exhausted from excavations or ground areas which are lower than the generally prevailing water level.

The invention has particular application to construction projects, such as tunnels, sewers, bridge pier foundations, etc. When a tunnel is to be built in a ditch or a bore, the contractor is often plagued by water which seeps into the ditch or bore from one source or another and makes it impossible to do the work unless the water can be kept out during the construction period.

For many years, this water has been controlled somewhat by a method employing a plurality of well points connected to a header which in turn is connected to one or more high-vacuum pumps.

The method of the present invention achieves a distinct advance over the old method and solves problems which have interfered with the efficiency and the satisfactory use of the old method.

One of the problems solved is that with the new method when the area around a well point goes dry, so to speak, and air is sucked into the line through the well point, there is no interference with the efiiciency or working of the other well points in the system. With the old suction pump and header method, when one or more well points went dry, the minus pressure (suction) of all the other well points would drop 3 and so would diminish their ability to pick up water and carry it up to the pump. Different plans have been tried in the past with the old method to shut ofi a particular well point suction line as soon as the operator became aware that its well point was sucking air. In the first place this has meant an operator inconstant attendance on the system and he has tried by watching glass tubes set in the suction line or by ear to detect which well point lines should be shut oil. The present method eliminates the need for an operator in constant attendance and provides a fool-proof, automatic dewatering system. This is not only an economy to all concerned, but the increased efficiency of the new system keeps holes dry which before never could be kept perfectly dry.

In describing the method, a suitable apparatus has been shown in the drawings, in which:

Fig. l is a schematic view in perspective showing the system as applied to a ditch;

Fig. 2 is a detail View in elevation,. partly in section, showing a form of individual jet pump and a form of well point; and

Fig. 3 is a like view of a form of air release.

In using these forms of devices to illustrate the application of my method and apparatus, I do not intend thereby to limit it, except as is required by the appended claims.

The apparatus shown in Fig. 1 includes a centrifugal pump I I! (normally classified as a vertically-split case or a horizontally split-case) driven by any suitable available power source I I. In this case it is an electric motor. The inlet [2 of the pump I is connected by a pipe to an air separation chamber and reservoir l4 for starting the system after a shutdown. The outlet of the pump I0 is connected to what I call a' high pressure header 16 from which the leads H, H, H, i! run to the individual jets l8 (see Fig. 2), each of which is positioned above and connected to the outlet of a well point l9. Shut off valves 20 in each lead 11 facilitate selection of the well points to put in service.

The well point 19 (see Fig. 2) includes a pipe 2! having an opening or series of openings 22, surrounded by a fine screen 23 with a heavier protecting screen 2311 around the whole. The outlet 24 of the well point is connected to the chamber 25 in the jet housing 26 by the pipe 21. This chamber surrounds the jet nozzle l8 and opens into the jet venturi 28, so that when the water or other liquid being pumped through the header i6 rushes from the nozzle !8 it creates a vacuum in the Venturi tube 28, thus lowering the pressure in the well point l9 and causing the water 29 around the well point to flow in through the screens, up into the Venturi chamber 25 and into the Venturi tube 28. There it mixes with the water from the nozzle [8, and the total of nozzle capacity and flow through the well point passes on up through the pipe 30 into the return or low pressure header 3! and into the reservoir l4. 7

On the return header 3|, at its highest point where air will collect, I prefer to put an automatic air vent valve 32, having a float 33 on an arm 34 which opens and closes the valve disc 35 on the outlet orifice 36 (see Fig. 3)

So long as water fills the system, the float remains buoyed up and holds the valve disc to its seat. As air accumulates, it displaces the water in the body of the valve and the float falls as the water recedes, thus pulling the disc off its seat. The accumulated air is then discharged by the pressure in the system. As the water rises in the body, the float returns the disc to its seat, and prevents water from escaping. When air collects again, the cycle is repeated. On a header 3| which is 4110 feet long there may be several of these air vent valves 32.

On each return line 30 is a valve 31 to be closed whenever the valve 20 on the pressure line I! is closed. This would be at a time when any particular well point was to be inactivated.

In an installation each set of branch leads I! and 30 are usually about 5 feet apart from the next set, but this distance may be varied to suit the volume of water that has to be withdrawn from the excavation.

The water picked up through the well points l9 represents-a surplus over; that being pumped down the line H, and will flow out the overflow of the tank l4, leaving in the tank all the liquid needed to keep the system primed and the header l6 and pipes l1 filled. The over flow is placed at a point higher than the inlet of the pump 10.

I have found that the systemaworkshwell with a pressure of 55 to 70 poundsinthe high pres? sure header l6 and with a pressure of to 15 pounds in the return or low pres sur e header -fil. The centrifugal pump [0 has to bebig enough to supply the demand of the combined capacities of the jet nozzles I8. Any number of these nozzlesxmaybeusedso long as the pump 10 has therequiredoutputa:g I 1 My new ,-system ,o,f dewatering is raccon plished byf theuse of a pluralityof ,jetsJB connected as .1. herein setforth sqthat if one or more wellpcints r'.l,9.s-have exceeded the flow of waterinto them through the openings, 22 and, are taking, in;;air, .-this will in nowaysaffectwor decrease,-the-;,efiiciencygof the other wellpoints which are still -,-,;submerged ,inawater; It was;; this discov this-new -method which solved the old p oblem, winherent in vacuum pumping, namely that when .Onepnmore well points began sucking, in air, the vacuum in the whole system decreasedand erefQre; th amount:- V?Q E;:: KQQ 9; v sthroug-h thewell p.oints-;still submerged; water dropped ofi, Zi'his meantthat in the old-method it wasnecessary,toexercise constantwigilance over the well; points;so that those-that w re glry,

e e h m n ou ib i fi p ans-yew.- hy a valve, Glass tubes torsighting.,-to detect we when awell point went :dry, and-listening to determin if-a mr ateLW fl wi iqn y a: 1. a ti ula "W911; 1 1 l-"13. 55: tam

we estr e i n e 101d me hod ,i h b i l ;Bv-- t e w em d r ea er nir swn possible to cut -downvon the laboriorcenecessary t ,,;k P;. Z Q-. s st m e in and i i efi ;1.f;I1 $.ib f Il a;.-iq to 1 p awa ,a di ve te at n u a ten d: y r.th lws k-eh n fi r le periods of time. This was unheard of with the s s ms n nnother yery distinct advantage .of ,t u

method is that it can be used in an excavation ide t sim l byvwnning he le om 7 the high 5 pressure ihea der ..i 6 I tusually, at the s r ace ei M-an h -p d roeia turnheader ,3], usuallyl also at the surface level) down into-.the,e xca-vationv no matter what tse e ih W il the m J han h {reservoir M ar kept un-on th wqrk n evelwh reth y are ,easy -to watch and to. repair, With th'e'gold ys m, ofu in m eh n calmi ps to: l f y water the l to 20 foot lift possible withfv ac ium madeit necessaryin any ,excavation of 15 2 t,- feet to? put ,another complete well point 1: sys m at th W0. f t l e I s [st qperated entirely independently of thefsystem at thehigher levellgf fhis visgcalled stagingland there had to ,be, .as many independent ,systems, one at each stage, as therewere multiples of feet inthe, depth of the excavation. in l. Thisindicates-too thatin-deep excavations under .-the old method of staging, thewcost of equipment goesup as each additional independem:unit s'r Sie v improved system also dispenses with the vaeuum pumpwvhich was needed on the old The net eifect of this new syste n is that it keeps the water level down below grade, "drying 4 up the sub-grade so the contractor is working the dry It does this withgangindividual jet installed at' each wel'lfipointli Noirialtter whether one or twenty well points are sucking part air 5,;with the water, or even all air, this does not a fgiect th performance of the system.

Nomatter whether the excavation is twenty .-.-g0r ;orty,;i'-eet deem; the supply pipes can still be for the ground surface, with just the individual 10 lines going down to the well points, because the actual, pumping, is done right above the point with the jet. This keeps the piping out of the way;- .completed sections can have the points removed and the excavation backfilled, with the 15: rPQZP-P *s PQY Qn PP QEQF; ne h l wit u disturbing the supply pipes.

f device. .of claim} together," with "a 'Q'fioat controlled air release meansin the fluid return 11118,, .3

i lsc n c e 7 1d, rese voir he mean ,the 4 level I pf he" inlet to said continuous fluid ing 3 inj which Zsaid "clonland aid'i ui po spcsed at or hear the id excavation.

" a ground level alongside v 'faomr T; "cunLnrroN.

Images