IS4I. 



THE CIVIL EXGIXEER AND ARCHITECT'S JOURxVAL. 



293 



ACCOCXT of SOUE plans adopted is the north of EXGLiND OF 

 SINKING TUllOUGH QUICE-SAXD. 



By EDWARD StaNi.ev, Engiueer, Sundprl;u)d. 



When a "winning" numbers nmongst its contingencies an encoimier 

 with a formidable quicksand, tlie preparations are, or ought to be, well 

 digested as to power and appliances to overcome it. The viewer, 

 engineer, and master sinker, each in their respective departments, 

 take a retrospect of the means used on former occasions at other places, 

 selecting the improvements that each adopted from previous works, 

 which give every new " winning" an opportunity of ])rofiting by the 

 p-sperience of the past. Boring by rods having determineil the dis- 

 tance the sand is situated from the surficc, and also the thickness of 

 the sand previously ; this operation is re<iuisite, as the pit has to be 

 chambered or bevelled like the friistrum of a cone, for the purpose of 

 driving the spiling and laying criljs, each length and round in the 

 descent being within the previous one. Supposing, for instance, the 

 pit is 15 feet diameter, and the saiKi five fathoms, or 30 feet, in depth, 

 and the spiling and cribs averaging each sis inches thick, and the 

 length of the spiles six feet, it remain? now to examine what must be 

 the diameter of the base of the frustrum of the cone, bevelled out so 

 as to have the pit of sufBcient size at the bottom of the sand as to ad- 

 mit the metal tubbing, and preserve the size of the pit It will be, of 

 course, premised that in sis feet lengths it will require for the 30 feet, 

 five lengths ; if fewer lengths could be driven through the sand, the 

 less the frustrum of the cone bevelled out in the rock ; but long lengths, 

 when driven, if the deviation is small, are like the trifling inaccuracy 

 o( an angle, which, if produced, are a long way out at the far end ; it 

 is, therefore, advisable to keep the lengths short, and in the annexed 

 diagram are five. The five rounds of spiles and cribs, according to the 

 former dimensions, will take U(> 10 feet of the diameter of the pit. 

 We must add a clear space round at the surface of the sand, a a, of J8 



Figl- 



inches, which will add to the former diameter tliree feet, making it 13 

 feet. Further, we have to add the breadth of wedging crib, b b, cut 

 at the bottom, and the space between its outer circumference and the 

 lowest crib of the last spile, c c, together two feet each, wdiich, added 

 again to the 13 feet, makes 17 feet. This summary is the extra dia- 

 meter over and above that of the pit, which we took at 15 feet, which 

 gives 32 feet as the diameter of the base of Uie frustrum of the cone. 



The height of this frustrum will depend upon the soundness of the 

 limestone in contact with the snnd. If not very sound, it must be car- 

 ried flirther up, both for the s ifety of the sinkers and efficiency of the 



wedging crib at the top of the tub. Tlie str.itum of quicks.inil is 

 shown by the letters d d, and the snperiiicumbejit limestone, e t, the 

 top, or closing crib, //, and the metal tubbing, if «- ; the manner of 

 putting in which is by an intervening layer of deaUheathing, at the 

 vertical and horizontal joinings, and subsequent wedging, has already 

 been given in the Mining Journal. No lelters of reference are put to 

 the spiles and cribs, as they will easily be recognized, each spile hav- 

 ing three cribs, at a distance apart of'atxjut two f^et. 



The following figure in perspective mav give a more general irlea 

 of the mode of spiling and cribing through 'the sand :— It will be per- 

 ceived that the spiles are 



driven round the pit in the 

 sand, and considerable atten- 

 tion and care is required on 

 the first round — and the rea- 

 son is, that when it is accom- 

 plished, and the three cribs 

 inserted, the lust of these acts 

 as a guide for the circular in- 

 sertion and driving of the suc- 

 ceeding s.t. Tlie cribs are kept up in their proper position by cleats 

 or brackets (see fig.) till a suificient external pressure keep's them 

 tight. The spiles may be lighter near the surface of the sand if thought 

 proper, and increase in thickness in the succeeding lengths with the 

 (jressure, but some consideration should at the same time he made for 

 the large diameter requiring increased strength. It may, therefore, 

 be consider- d a prudent error to be too strong instead of too weak. A 

 bird's eye view of the spiling, when complete, presents in principle an 

 analogy to the elongation of a telescope. 



It may appear paradoxical to a person unacquainted with the dis- 

 trict, to be told tliat the quicksand sometimes presents itself in the 

 form of a hard rook, requiring the liberal use of gunpowder to detach 

 it. This stone is very porous, through which immense quantities of 

 water filter, and which, by a continuous, running, increase the size of 

 the apertures, along which are at the same time conveyed a large 

 quantity of sand to the pit. This result is technically called "gutter- 

 ing," and, on any cessation of pumping, and consequent rising of the 

 Fi:j. 3. water, it increases to a great extent. As the 



water is being drawn out of the pit, its reced- 

 ing from the gutters brings along with it sand, 

 and hence their enlargement. 



The annexed fig. shows a gutter fallen on to 

 the limestone roof. At the bottom will be per- 

 ceived a stream proceeding from the far end, 

 having tributary ones from each side. These, 

 in some cases, keep filling up the liottom of the 

 pit with sand, nearly as fast as it can be sent to 

 bank. With a sand of this kind, the general 

 aim is, to keep the water always down if pos- 

 sible, for it has been found tha't its rising in- 

 variably increases this guttering, which proceeds 

 in long irregular chasms radiating from the 

 shaft. 



As "spiling" cannot be driven under circumstances of this kind, the 

 cribbine- and lathing is put into the pit in sections, as shown in the 

 annexed fig., varying in depth according to circumstances, and as the 



sand can be excavated. These sec- 

 tions, when t)ie round is complete, 

 are kept together vertically by hang- 

 ing deals, which are planks spiked 

 to the previous rounds, or if it be the 

 first round, to some suitable provision 

 in the shaft; external pressure soon 

 binds them horizontally. In some 

 cases the sand becoraes'soft towards 

 the bottom, and the sections are 

 abandoned for spiling. 

 The foregoing details are enumerations of the resources hitherto 

 applied, which appear, and, indeed, have been found in practice to 

 answer best. In cases of difficulty, parties having works of this kind 

 in hand are frequently favoured with friendly suggestions, the most 

 popular of which appears to be the suspension of a cylindrical iron 

 vessel, of proper diameter, which it is proposed to lower and lengthen 

 at the top a-s the excavation proceeds. This suggestion has certainly 

 feasibility about if, though it is said to have originated from an ama- 

 teur. 



The present article may not inaptly close with a brief notice of tlie 

 Datton "winning," which is going on slowly but suiely. The most 

 determined and persevering spirit is shown by the owners fXIessrs. T. 

 R. G. Braddyll and Co.), and the viewer. The outlay of money is im- 



