Patent Publication Number: US-9896894-B2

Title: Drilling and grouting method and apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a U.S. National Stage application of International Appl. No. PCT/EP2012/076766 filed 21 Dec. 2012, which claims priority to U.S. Provisional Application No. 61/720,492 filed 31 Oct. 2012, the entire disclosures of which are hereby incorporated by reference in their entireties. 
    
    
     FIELD OF THE DISCLOSURE 
     The present disclosure generally relates to the field of ground drilling and grouting, and more particularly to reverse circulation rotary drilling. 
     More specifically, the present disclosure concerns a drilling and grouting device, a drilling and grouting machine comprising such drilling and grouting device, and a drilling and grouting method using such machine. 
     The apparatus and method according to the present disclosure are particularly intended to improve poor-quality ground to facilitate tunnelling or excavating. The apparatus and method may also be used in dam rehabilitation or remedial work on or around dams among other things. Due to its versatility, the apparatus can be utilized when drilling directly from ground level or from a barge on off shore applications. 
     BACKGROUND OF THE DISCLOSURE 
     Reverse Circulation rotary drilling, also known as “RC Drilling” or “Dual Wall Drilling”, has been used to sink boreholes into the ground for example, for mineral exploration. 
       FIG. 13  shows an exemplary device for such Reverse Circulation rotary drilling, employing a dual wall pipe  122  comprising an outer drill rod  124  with an inner rod  126  located inside said outer drill rod  124  and provided with a drill bit  140  at its distal end. 
     A drilling fluid, which may be high pressure air or water, is passed in the outer flow path defined between the outer and inner rods  124 ,  126 , down to the drill bit  140 . Once the drilling fluid hits said drill bit, the cuttings mixed with the said fluid are forced up to the center of the bit and back up the inner tube  126 . Cuttings are so returned to the surface and collected for later use. 
     This kind of tooling, however, is not appropriate for grouting operations. 
     Injection of the grout through the annular space between the outer and inner rod is undesirable, particularly when the grout has a high viscosity and is of low mobility. Due to the large ‘wetted-perimeter’ of this annular space, there is a high risk that the grout may plug the device. 
     Injection of the grout through the inner rod can damage and/or destroy the drill bit. Also, the drill bit prevents free flow of grout into the drill hole, particularly when the grout is of low mobility. 
     Taking the inner rod and the drill bit out of the outer drill rod, to allow for the free flow of grout into the outer drill rod is time-consuming and presents problems when drilling and grouting operations must happen very quickly. Likewise, removing the dual wall pipe for introducing a separate injection device in the drill hole also necessitates much time and additional equipment. 
     SUMMARY OF THE DISCLOSURE 
     In view of the foregoing, there is a need for a method and apparatus which enable both drilling the ground and injecting grout into the obtained borehole efficiently, in particular quickly and easily while preventing plugging. It is an object of the present disclosure to provide such method and apparatus. 
     According to embodiments of the present disclosure, there is provided a drilling and grouting device, comprising a drill string including a hollow elongate outer rod having a central axis and a hollow elongate inner rod located coaxially within said outer rod, wherein a first outer flow path is defined between said inner and said outer rod, and a first central flow path is defined inside said inner rod, a drill bit aligned with said inner rod along said central axis and including a second central flow path, and a crossover part interposed between said inner rod and said drill bit along said central axis, said crossover part being configured to connect the first central flow path with a second outer flow path surrounding the drill bit to form a main path and to connect said first outer flow path with said second central flow path to form a secondary path. 
     The present disclosure thus provides a single device suitable for drilling the ground and subsequently injecting grout into the ground, without removing the device between the drilling and grouting stages. 
     Drilling fluid, usually air, water or a mix of both, injected in the annular space between the outer and inner rod is deviated by the crossover part towards the inside of the drill bit. 
     When entering into the drill hole, drilling fluid is mixed with the cuttings produced by rotation of the drill bit. In a normal case, in which the ground is relatively impermeable, the mix of cuttings and drilling fluid is returned back to the surface by being pushed by drilling fluid constantly entering the drill hole. The mix of cuttings and fluid enters the second outer flow path surrounding the drill bit and moves upwards through the crossover and through the first central flow path, generally towards a waste-collection tank. 
     After drilling has been completed, grout is pumped down though the main path. It passes through the first central flow path, crosses-over and flows around the drill bit and into the ground formation. 
     Rates of drilling and grouting production can be greatly increased over conventional drilling methods. 
     Another benefit of the disclosure is that during the grouting phase, the grout is separated from the environment with a ‘double-protection’ system. The grout or the cuttings flowing through the inner rod of the drill string are ‘double-protected’ in that they do not flow into the surrounding ground or sea even if the inner or the outer rod breaks. This might be important in situations where the system drills through contaminants, or in environmentally sensitive areas. 
     Moreover, both cuttings and grout flow through the inner rod, which circular section is much more adapted to avoid plugs and facilitate the flow than the annular space defined between the outer and the inner rod. 
     It is further to be noted that the drilling and grouting device according to the present disclosure can be used on projects where inclined drilling is required. It could even be used in horizontal drilling. 
     As an example, the application of this type of drilling for remedial drilling/grouting work on, and surrounding, dams is particularly advantageous. 
     Generally, the crossover part comprises at least one main connecting duct for connecting the first central flow path with the outside of the drill bit and at least one secondary connecting duct for connecting the first outer flow path with the second central flow path. 
     Advantageously, the crossover part comprises at least two main connecting ducts, regularly distributed circumferentially. 
     In the same manner, the crossover part preferably comprises at least two secondary connecting ducts, regularly distributed circumferentially. 
     As indicated above, in a case where the ground is relatively impermeable, the cuttings are forced to move upwards in the main path by being pushed by the drilling fluid. 
     According embodiments of the disclosure, a bypass is provided between the secondary path and the main path for deviating a part of the fluid circulating through said secondary path towards said main path. For example, such bypass may be provided between the secondary path and the second outer flow path for deviating a part of the fluid circulating through said secondary path towards said second outer flow path. This is particularly adapted to cases where the ground is moderately permeable, that is, a part of the drilling fluid moves upwards with the cuttings, but not sufficiently to avoid plugging of the cuttings in the main path. The bypass ensures that at least a predetermined amount of water is not lost in the ground but mixed with the cuttings which enter the second outer flow path. 
     The bypass can be provided with a check valve. 
     Also the drill bit is advantageously provided with a check valve. Such check valve can prevent the flow of grout up into the crossover part and into the annular space between the outer and inner rod, that is, into the first outer flow path. 
     The crossover part and the hollow elongate outer rod are adapted to rotate as a single unit. 
     According to another aspect of the disclosure, there is provided a drilling and grouting machine, comprising 
     a drilling and grouting device having a drill string including a hollow elongate outer rod having a central axis and a hollow elongate inner rod located coaxially within said outer rod, wherein a first outer flow path is defined between said inner and said outer rod, and a first central flow path is defined inside said inner rod, a drill bit aligned with said inner rod along said central axis and including a second central flow path, and a crossover part interposed between said inner rod and said drill bit along said central axis, said crossover part being configured to connect the first central flow path with a second outer flow path surrounding the drill bit to form a main path and to connect said first outer flow path with said second central flow path to form a secondary path; 
     a first moving device for rotating said drilling and grouting device about its central axis; 
     a second moving device for vertically moving said drilling and grouting device in a direction parallel to the central axis; 
     a drilling fluid supplying device connected to the secondary path for supplying said secondary path with drilling fluid; and 
     a grout supplying device connected to the main path for supplying said main path with grout. 
     According to still another aspect of the disclosure, there is provided a drilling and grouting method, comprising the steps of 
     providing a drilling and grouting machine comprising a drilling and grouting device having a drill string including a hollow elongate outer rod having a central axis and a hollow elongate inner rod located coaxially within said outer rod, wherein a first outer flow path is defined between said inner and said outer rod, and a first central flow path is defined inside said inner rod, a drill bit aligned with said inner rod along said central axis and including a second central flow path, and a crossover part interposed between said inner rod and said drill bit along said central axis, said crossover part being configured to connect the first central flow path with a second outer flow path surrounding the drill bit to form a main path and to connect said first outer flow path with said second central flow path to form a secondary path a first moving device for rotating said drilling and grouting device about its central axis; a second moving device for vertically moving said drilling and grouting device in a direction parallel to the central axis; a drilling fluid supplying device connected to the secondary path for supplying said secondary path with drilling fluid; a grout supplying device connected to the main path for supplying said main path with grout, 
     rotating said drilling and grouting device about its central axis, 
     moving said rotating device downwardly in the ground, and 
     controlling said drilling fluid supplying device for supplying the secondary path with drilling fluid, 
     collecting the cuttings moved upwards through the main path, and 
     controlling said grout supplying device for supplying the main path with grout, to inject grout in the ground. 
     In some cases, when the ground is very permeable, the drilling fluid can be lost in the ground, and may not move upwards with the cuttings through the main path. Consequently, part of the cuttings is left in the ground. In some cases, the circulation of drilling fluid (downwards through the secondary path and then upwards, mixed with the cuttings, through the main path) is stopped when the main path is already partially or fully filled with cuttings. Attempts to pump grout back down the main path may then lead to plugging of the drill bit and the crossover part. 
     According to the disclosure, by injecting drilling fluid both through the main and the secondary paths during drilling, plugs of cuttings in the main path may be avoided. 
     According to some embodiments, the method may comprise bypassing part of the drilling fluid supplied to the secondary path to said second outer flow path. As indicated above, this may be particularly advantageous in cases where the ground is moderately permeable, that is, a part of the drilling fluid moves upwards with the cuttings, but not sufficiently to avoid plugging of the cuttings in the main path. 
     According to some aspects of the disclosure, there is provided a crossover part configured for being assembled to a drill string of a drilling and grouting device including a hollow elongate outer rod and a hollow elongate inner rod located coaxially within said outer rod, said crossover part comprising a central axis and, at one axial end, at least a first centered opening adapted to be connected to said first inner rod and at least a first offset opening adapted to be connected to a flowpath defined between said outer rod and said inner rod, and at its axially opposed end, at least a second centered opening and at least a second offset opening, the first centered opening being connected to the second offset opening and the first offset opening being connected to the second centered opening. 
     The first centered opening may be connected to the second offset opening by at least one main connecting duct. In the same manner, the first offset opening may be connected to the second centered opening by at least one secondary connecting duct. 
     It is to be understood that, except in cases of clear incompatibility and unless otherwise stated, features of one embodiment or example described herein can similarly be applied to other embodiments or examples described herein. 
     Other features and advantages of the disclosure will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings, like reference signs generally refer to the same parts throughout the different views. 
         FIG. 1  is a schematic illustration of a drilling and grouting device according to embodiments of the present disclosure, with arrows showing the flow of water and cuttings during the drilling phase, 
         FIG. 2  shows the device of claim  1  during the grouting phase, 
         FIG. 3  is a schematic illustration of a drilling and grouting device according to embodiments of the present disclosure, 
         FIG. 4  shows still another device according to embodiments of the present disclosure, 
         FIG. 5  is a schematic flow diagram during a typical drilling phase, 
         FIG. 6  is a schematic flow diagram during a grout flushing phase, 
         FIG. 7  is a schematic flow diagram during a grouting phase, 
         FIG. 8  is a schematic flow diagram during a drilling phase, in a case where the ground is very permeable and the drilling fluid is mainly lost therein, 
         FIG. 9  is a schematic illustration of a drilling and grouting machine according to the present disclosure, 
         FIG. 10  shows different steps of a drilling and grouting method according to embodiments of the present disclosure, and 
         FIG. 11  illustrates an embodiment of the disclosure, particularly adapted for drilling on water sites, 
         FIGS. 12A to 12C  illustrate the positioning of the protection casing shown in  FIG. 11 , 
         FIG. 13  illustrates a drilling device known from the prior art. 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description refers to the accompanying drawings showing examples of the drilling and grouting device according to the present disclosure. It is intended that these examples be considered as illustrative only, the scope of the disclosure not being limited thereto. 
       FIG. 9  is a schematic illustration of an exemplary drilling and grouting machine according to the disclosure, for improving and/or sealing the ground. 
     The drilling machine  10  includes a frame or tracked vehicle  12  which may be disposed on an offshore platform or on land. A drilling mast  14  is mounted on said frame, in an articulated way, as well as other equipment such as a control console  16  of the drilling machine  10 . 
     A carriage  19  slides along the drilling mast  14 . Said carriage  19  supports a drill head  18  to which the drilling and grouting device  20  is mounted. 
     The drilling and grouting device  20 , which will be described in more detail hereafter, comprises a drill string  22  composed of a hollow elongate outer rod  24  and a hollow elongate inner rod  26  located coaxially within said outer rod (see  FIG. 1 ). 
     The drill string  22  is connected to a plurality of supplying or collecting devices  90 ,  91 ,  92 ,  93 . 
     The annular space defined between the inner and outer rods  24 ,  26  communicates with a drilling fluid supplying device  93  provided with a controllable valve D (see  FIG. 5  for example). A swivel  32  mounted just below the drill head  18  is provided to connect said annular space with said drilling fluid supplying device  93 . 
     The interior of the inner rod  26  communicates with a central pipe  30  connected to the drill head  18  and to a grout supplying device  90 , a water supplying device  91  and a discharge device  92 . Each of said devices  90 ,  91 ,  92  are also provided with controllable valves, respectively C, B, A. 
     The drilling and grouting device  20  may be rotated about its axis A by means of the drill head  18 , and moved jointly with the carriage  19 , in a direction parallel to its axis A. 
     For the following description, the axis A of the drilling and grouting device is the common central axis of the inner and outer rod of the drill string (hereafter also “central axis”). The axial direction corresponds to the direction of said central axis, and a radial direction is a direction perpendicular to said central axis. Similarly, an axial plane is a plane containing the central axis, and a radial plane is a plane perpendicular to said central axis. Finally, unless specified to the contrary, adjectives such as “inner” and “outer” are used relative to a radial direction such that an inner portion (i.e. a radially inner portion) of an element is closer to the central axis than is an outer portion (i.e. the radially outer portion) of the same element. 
     In the present application, “upstream” and “downstream” are also defined relative to the direction of drilling (from upstream to downstream). 
     To achieve the desired drilling depth, several assemblies each comprising an outer and an inner drill tube disposed coaxially and linked together, for example by discrete welding points, are attached successively, one to the other. The link between two successive outer tubes  241 ,  242  (see  FIGS. 9 and 10 ) may preferably be performed by screwing a threaded end of an outer rod  241  to the threaded end of a contiguous outer rod  242 . The inner tubes may fit to each other through O-ring press fit for example. When possible/practical, the drilling and grouting device of the disclosure may be used in conjunction with a leader-system long enough to allow for ‘single-pass’ drilling and grouting, with no need to add or remove each assembly as the drill bit is advanced or withdrawn from the drill-hole.  FIG. 1  shows the lower end of the drill string  22  of  FIG. 9  and illustrates in more details the drilling and grouting device  20  according to the present disclosure. 
     The drilling and grouting device  20  comprises, downstream of the drill string  22 , disposed along the central axis A, a drill bit  40 , for example in the form of a tricone bit, configured to cut the ground. 
     The drilling and grouting device further comprises a crossover part  50  axially interposed between the drill string  22  and the drill bit  40 . 
     In the example shown in  FIGS. 1 and 2 , the outer rod  24  of the drill string  22  is extended by means of an outer drilling casing  28  threaded thereto and provided with drilling teeth  29  at its end. In other possible configurations, the outer casing  28  may be formed in one piece with the outer rod  24  of the drill string  22 . 
     The outer casing  28  serves to surround the crossover part  50  and, eventually, a part or the entirety of the drill bit  40 . 
     In the example shown in  FIGS. 1 and 2 , the crossover part  50  has a generally elongated shape, with tapered portions  52 ,  54  at each end. 
     In the illustrated example, the crossover part  50  comprises, between those tapered portions, a central part  56  forming a circumferential protrusion. This central part  56  is adapted to cooperate with an aperture formed in the outer casing  28 . Crossover part  50  and outer casing  28  may further be fixed by fixing means such as welds, thereby ensuring that they move as a single piece. 
     Any other configuration or shape allowing that the crossover part has an external maximum diameter at least equal to the inner diameter of the outer casing is also acceptable. 
     The first upstream end  52   a  of the crossover part  50  is connected to the lower end of the inner rod  26  by O-ring press fit connections  27  for example. 
     More generally, the system according to the present disclosure advantageously uses a drill string  22  with threaded connections from outer-tubes to outer-tubes (for torque) and a built-in inner rod with ‘floating’ connections (O-ring press-fit, see o-ring  27  on  FIG. 1  for example). 
     The crossover part  50 , connecting the outer rod  24  with the inner rod  26 , allows that the torque be transferred from the single drill head  18  to the outer rod  24  only. There is no need to transfer torque to the inner rod  26 , no need for a double-head drill, and no need for a duplexing system. The inner rod is less mechanically strained, and therefore less inclined to break. 
     At its first end  52   a  oriented upstream, the crossover part  50  comprises a first centered opening  60  (here aligned with the central axis A) adapted to be connected to the first inner rod  26  of the drill string  22 . This first centered opening  60  is connected by a first oblique connecting duct  62  to an offset opening (hereafter second offset opening)  64  formed on the periphery of the downstream tapered portion  54  of the crossover part  50 . 
     At the periphery of its first upstream tapered portion  52 , the crossover part  50  further comprises an offset opening (hereafter first offset opening)  66  connected by a second oblique connecting duct  68  to a second centered opening  70  (here aligned with the central axis A) formed at its opposite end and adapted to be connected to the drill bit  40 . 
     With the above described configuration, the passages formed in the drilling and grouting device  20  according to the present disclosure are as follows: 
     Upstream from the crossover part  50 , a first central flow path  82  is defined inside the inner rod  26 , and a first outer flow path  80 , usually in the form of an annular area, is delimited by the inner rod  26 , the upper part of the crossover part  50 , the outer rod  24  and the outer casing  28 , and communicates with the first offset opening  66  of the crossover part  50 . In the illustrated example, the first outer flow path  80  terminates between the outer casing  28  and the first tapered portion  52  of the crossover part  50 . 
     Downstream from the crossover part  50 , a second central flow path  84  is defined inside the drill bit  40 . A second outer flow path  86  is further defined radially outside the drill bit, between the outer casing  28  and both the second tapered part  54  of the crossover part  50  and the drill bit  40 . 
     The crossover part  50  allows the first central flow path  82  to be brought into direct communication with the second outer flow path  86 . The path comprising the first central flow path  82 , the connecting duct(s) of the crossover parts connected thereto and the second outer flow path  86  is referred to, in the present description, as the main path  110 . This main path has, on its almost entire length (all along the drill string), a circular section which is optimal for the flow of materials, in particular materials having a moderate or high viscosity. 
     In the same manner, the crossover part  50  allows the first outer flow path  80  to be brought into direct communication with the second central flow path  84 . The path comprising the first outer flow path  80 , the connecting duct(s) of the crossover parts connected thereto and the second central flow path  84  is referred to, in the present description, as the secondary path  112 . The secondary path  112  has, over almost its entire length (all along the drill string), a general annular section. 
     The drilling and grouting operations, completed with the above described device, will now be explained in more detail with reference to the figures. 
       FIG. 10  schematically illustrates the main steps of a drilling and grouting method according to an embodiment of the present disclosure. 
     In a first step referenced S 1  on  FIG. 10 , the drill string  22  is rotated jointly with the drill head  18  (see  FIG. 10 ), about its central axis A, and moved downwards along the mast  14 , jointly with the carriage  19 , until the drill bit reaches a depth D 2 . 
       FIG. 1  shows the drilling and grouting device of the disclosure during this typical drilling phase, corresponding to the configuration of  FIG. 5 . 
     Drilling fluid (DF), usually water, is injected into the annular area  80  between the outer and inner rod  24 ,  26 , that is, in the secondary path  112 , by controlling a valve D of the first drilling fluid supping device. The valve A provided on the cuttings discharge flow path is also open (see the corresponding flow diagram of  FIG. 5 ). 
     Compressed air can advantageously be added to the water that is pumped into the swivel  32  during the drilling operation. This combination of water and air could aid in the upward ‘circulation’ of the cuttings—creating a type of air-lift. 
     Drilling fluid enters the first offset opening(s) of the crossover part  50  and is led by said crossover part  50  towards the center of the drill bit  40 , where it helps cooling the drill bit  40  and softening and cutting the ground 
     Drill cuttings mixed with drilling fluid (CU), travel around the outside of the tricone bit  40 , crossover and travel upwards through the inner rod  26 . Cuttings flow up through the drill head&#39;s central passage and are directed down to the discharge device  92 , for example a waste-collection tank. 
     Once the drilling operation has been completed, the drilling and grouting device  20  is slowly moved upwards up to a depth D 1  and, simultaneously, the grouting operation is performed. 
     Before grouting, the main path  110  may be flushed with water (W). As illustrated on  FIG. 6 , the valve C controlling the water supplying device  91  is open while other valves A, B and D are closed. 
     The main path  110  is thereby cleaned and the operator can determine that said main path  110  is not plugged and that grouting can be performed. 
     In a second step S 2 , grout is then pumped down through the main path  110 . It flows through the circular passage  82  of the inner drill rod  26 , then crosses-over and flows around the tricone bit  40  and into the ground formation. 
     As shown in  FIG. 7 , the valve B of the grout supplying device  90  is open while the other valves A, C and D are closed. 
     A check-valve  42  is installed inside the tri-cone bit  40  for preventing the flow of grout up into the secondary path. 
     The drilling and grouting device  20  according to the disclosure has the advantage that during this grouting phase, the grout is separated from the environment with a type of ‘double-protection’ system. The pumping of grout through the inner rod  26  of the drill string  22  provides protection from a rupture from the inner rod  26  or from the outer rod  24 . Also the drilling spoils are ‘double-protected’ from the environment during the drilling phase of the operation, which might be important in situations where the system might drill through contaminants. Also, because the torque is transferred from the drill head directly and only to the outer rod  24  (that is, to the succession of outer tubes forming the outer rod), the risk that the inner rod  26  breaks is reduced. 
     Once grouting has been completed between the depths D 1  and D 2 , the drilling and grouting device  20  is lowered again to the bottom of the grouted layer (here, depth D 2 ), and drilling is started again down to a depth D 3 . 
     The drilling and grouting steps are then repeated until the bottom of the desired grouting area is reached. 
     The device is finally removed from the ground as shown as step S 5  on  FIG. 10 . 
     In a particular embodiment illustrated in  FIG. 8 , when the ground to is very permeable, the drilling fluid is lost therein and cannot push the cuttings back to the surface. In order to avoid that the cuttings start moving upwards and get stuck inside the device, it is preferable that the cuttings be prevented from entering the device. With this aim, during the drilling step, water may be supplied not only to the secondary path, but also to the main path, by the water supplying device  91 . 
     The embodiment described hereabove is not limitative of the present disclosure. 
       FIG. 3  shows another device according to embodiments of the disclosure. 
     This device comprises a bypass  51  between the secondary path  112  and the second outer flow path  86  for deviating a part of the fluid circulating through said secondary path  112  towards said second outer flow path  86 . 
     In the illustrated example, the bypass  51  is arranged to connect the secondary connecting duct with the second outer flow path  86 . Such bypass  51  enables that sufficient water be provided to the cuttings, notably in case of moderate permeable ground, when part of the drilling fluid is lost in the ground. It may advantageously be provided with a check valve  53  to avoid return of the drilling fluid into the crossover part  50 . 
     Preferably, the bypass passage angles upwards (in the upstream direction), otherwise the flow of drilling fluid may conflict with the circulation of the cuttings that should be flowing ‘up’. In such case, drilling fluid may advantageously comprise drilling water and added compressed air. 
       FIG. 4  shows another device according to embodiments of the disclosure. 
     In this device, the crossover part  50 ′ and the outer casing are in one single piece. The crossover part  50 ′ comprises an outer casing part  55  that is threaded to the end of the outer rod  24 ′. 
     In some cases, the ground to be improved is under water. In such over-water drilling applications, a tertiary isolation/protection system may be used as shown in  FIG. 11 . This protection system may comprise an oversized protection casing  94  that is drilled into the sea-floor, for example 1-2-m. 
     This protection casing or tertiary containment pipe  94  surrounds the drill-string  22  and is fitted at its upper end with a diverter-head  97  for capturing any spoils or grout that may have migrated around the outside of the drill-string, and up into the water. The diverter-head  97  may be sealed around the drill-string  22  using a conventional rubber seal  98 . It may be further connected to an evacuation pipe  103 , for evacuating the spoils (see  FIG. 11 ). 
     The protection casing  94  may be installed using a clamping system  96  as illustrated in  FIG. 11 . 
     The clamping system comprises a U-shaped clamping part  96 , each leg  99   a ,  99   b  thereof having a planar contact surface adapted to come into contact with a flat outer surface of the outer rod  24  of the drill string. In the illustrated example, both planar surfaces are parallel and opposed to each other. 
     The clamping part  96  further comprises a protrusion  100  extending from one of its legs  99   a , forming a stopper. 
     As shown in  FIG. 11 , a bolt-flange  95  is connected to the upper end of the diverter-head  97 . A lug  102  protrudes from the upper face of said blot-flange  95 . 
     The clamping part  96  is adapted to be disposed on the bolt-flange  95  in such a manner that the stopper  100  cooperates with said lug  102 . Thereby, once the drill string  22  is introduced between the legs  99   a ,  99   b  of the clamping part  96 , the rotary movement of the drill string  22  is transferred, through the clamping part  96 , to the bolt-flange  95  and therefore also to the diverter head  97  and to the protection casing  94 . 
       FIGS. 12A to 12C  schematically illustrate how this protection casing is set up. 
     As illustrated in  FIG. 12A , the protection casing  94  is firstly introduced in the water down to the sea bottom. The diverter head  97  is, at this point, disposed a few meters above the sea level. 
     The drilling and grouting device is then introduced, in part, inside the protection casing ( FIG. 12B ). The clamping device  96  is disposed on the bolt-flange  95 , the evacuation pipe  103  is disconnected from the diverter head  97  and the drill head  18  is rotated and moved downwards along the mast  14  ( FIG. 12C ). 
     Due to the clamping device, the protection casing  94  is so to say “drilled” into the sea-floor. In order to better penetrate the see floor, the protection casing  94  is preferably supplied with cutting teeth welded to its lower end (not shown). 
     Throughout the description, including the claims, the term “comprising a” should be understood as being synonymous with “comprising at least one” unless otherwise stated. In addition, any range set forth in the description, including the claims should be understood as including its end value(s) unless otherwise stated. Specific values for described elements should be understood to be within accepted manufacturing or industry tolerances known to one of skill in the art, and any use of the terms “substantially” and/or “approximately” and/or “generally” should be understood to mean falling within such accepted tolerances. 
     Where any standards of national, international, or other standards body are referenced (e.g., ISO, etc.), such references are intended to refer to the standard as defined by the national or international standards body as of the priority date of the present specification. Any subsequent substantive changes to such standards are not intended to modify the scope and/or definitions of the present disclosure and/or claims. 
     Although the present disclosure herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present disclosure.