CA2900182A1 - Method and apparatus for culvert crushing - Google Patents

Abstract

A method for deforming an existing hollow pipe comprised of ductile material in an inward radial direction as it is being swallowed by an equal or larger sized replacement casing.

Description

METHOD AND APPARATUS FOR CULVERT CRUSHING
[0001] Corrugated steel (metal) pipe or CMP has long been widely used for culverts underneath rail and automobile roadways to conduct surface water under the roadway to prevent flooding and erosion. Such pipe is respected for its stout resistance to collapse and relative long life with respect to corrosion when galvanized. Many elevated roadways designed using corrugated steel culverts, which occurred as early as 1900 have exceeded the useful life of the steel. Typically the bottom rusts through causing loss of hoop integrity and therefore loss of load carrying capability. Said rusted culvert may result in collapse of the roadway above the pipe which in turn restricts or stops flow through the pipe. In the case of highways; ride on the road may suffer, or in the case of railways, potentially dangerous deviations in track alignment may result. In all cases loss of flow increases risk of erosion to the elevated section and may further degrade or destroy the integrity of the roadway.

[0002] Replacement of said aging culverts can be problematic as the traffic density of the roadways has typically increased over time and the option of shutting the roadway down for several days to make the replacement can be unacceptable from perspective of cost and user inconvenience. For this reason the process of culvert swallowing was developed. Deteriorated culverts had a nominally concentrically placed steel casing installed using pipe ramming techniques. It was intended that the culvert then be extracted from the steel casing and the steel culvert be lined with concrete or pipe of a material resistant to long term degradation. In some cases the culvert, with tightly packed, trapped soil surrounding the corrugations and sandwiched between the walls of the steel casing, was not able to be removed without extraordinary means.
These included hydraulic jacks, torch cutting of the CMP and other more passive means as explained in Crane 7,993,078, which is incorporated herein by reference.

[0003] The method described herein eliminates the friction between the host corrugated pipe and the outer casing by deforming the circular profile of the culvert pipe into a non-round, preferably cloverleaf profile. By relieving the culvert of annularly trapped soil induced friction, the deformed pipe may be extracted from the casing relatively easily with the towing force of an excavating machine such as a track hoe or dozer. At this point the process can continue expeditiously by installing new concrete or other long lived pipe in the now empty volume of the pipe rammed steel casing.

[0004] The method makes use of the considerable dynamic thrust produced by pneumatic pipe rammers when performing the pipe ramming method. Axial forces, lasting mere milliseconds, drive a steel casing axially through the ground. These high forces result from the repeated percussive blow of a striker against the internal forward end of the pneumatically actuated hammer. The high forces make it possible for the annular face of the steel casing to displace the soil or rock local to the face of the casing as well as overcome the outer skin friction between the soil and the steel casing.

[0005] These rammers are capable of percussively thrusting steel casing from 1 foot to 10 foot diameter of wall between 1/2" and 1-1/2" through various types of soil for distances up to several hundred feet. The value of the method lies in the ability of the work to be done trenchlessly, from the sides of the roadway, thereby allowing the roadway to remain in use.

[0006] In the pipe crushing method, the hammer is expected to perform an additional operation, that of ductile deformation of the existing CMP culvert. Said culvert is deformed in a progressive manner, from the outer surface of the culvert such that the hoop integrity is exceeded. While it may seem straightforward that a rusted through culvert lacking its hoop strength could be deformed with relative ease, it can be expected that some portions of the length of the culvert will maintain integrity and be difficult to deform. Therefore to provide a high degree of success, the method works with both CMP in good shape as well as CMP
that is corroded through the depth of its wall.

[0007] Progressive deformation is achieved with guide ramps within a crushing tool configured to be nominally the same size as the swallowing casing. The crushing tool is deployed near the front end of the casing being driven by the hammer and advances along with the steel casing as it is driven forward in an axial direction. The ramps yield the steel of the CMP

locally along the contact point of the rail such that any material spring back after passing the ramps does not permit more than incidental contact with the steel casing inside diameter. The crushing tool passes the entire length of the culvert or it may crush the majority of the culvert and push the last 5-10% out of the bore. For this reason it is advantageous not to place the crushing ramps too near the mouth of the tool as the tool nose exits the bore before the CMP is pushed out.

[0008] As the CMP is often a rolled steel product of considerable yield strength, it can be appreciated that the deformation or crushing process be gradual rather than abrupt in nature.
Ramps should be stout so as to resist being bent and the contact points of the rail should be both wear resistant and of high strength to resist pitting or grooving that would increase friction against the surface of the CMP. The ramps may be of compound angles as the initiation of yield in the CMP will require very high levels of radial force and continued deformation into the cloverleaf shape may require lower levels of radial force once the buckle in the surface of the CMP has been established. Further, the buckle may become sufficiently tight that it could pinch or drag upon the ramp, so considerations should be made along the length of the ramp for the width of the ramp and how the deformed CMP will interact.

[0009] The culvert can be crushed into a number of rational shapes to cause its outermost points to fit within a steel casing and provide the room to allow the trapped soil to come away from the steel casing inside diameter. These include an exaggerated kidney bean shape, a three lobe cover leaf or any sort of four or five pointed star. Note: the more bends (more lobes) the greater the level of plastic work being done to the CMP and therefore the slower progress will be made. Further a two lobe shape would perform the needed task of collapsing the majority of the walls away from the steel casing inside diameter, however it will be appreciated that the lobe dimensions end to end may expand beyond the original round dimension as the shape is formed, thereby requiring yet a larger steel casing, something disadvantageous to the process.

SUMMARY DESCRIPTION OF THE FIGURES

[0010] Figure 1 is an isometric view of a section of the Earth's surface containing an elevated railway that interrupts a surface drainage plane.

[0011] Figure 2 is a top view of the elevated railway having a culvert there through.

[0012] Figure 3 is section A-A of Figure2.

[0013] Figure 4 is a modified isometric view of an elevated railway with the culvert replacement method initiated.

[0014] Figure 5 is a top view of an elevated railway with the culvert replacement method initiated.

[0015] Figure 6 is section B-B of Figure 5 with the culvert replacement method initiated.

[0016] Figure 7 is detail C of Figure 6.

[0017] Figure 8 is a front view of the culvert crushing device.

[0018] Figure 9 is a side view of the culvert crushing device.

[0019] Figure 10 is a modified isometric view of the crushing ramp used in the crushing device.

[0020] Figure 11 is a top view of a culvert replacement process with culvert crushing slightly more than one half completed.

[0021] Figure 12 is section view D-D of figure 11.

[0022] Figure 13 is detail E of Figure 12.

[0023] Figure 14 is a modified isometric view of a casing that has replaced a culvert.

[0024] Figure 15 is a cross section of a culvert after crushing deformation by a three ramped tool.

[0025] Figure 16 is a cross section of a culvert after crushing deformation by a one ramp tool.

[0026] Figure 17 is a top view of a crushed culvert with parallel wire ropes alongside.

[0027] Figure 18 is section view G-G of Figure 17.

[0028] Figure 19 is an isometric view of a linear winch mounting fixture.

[0029] Figure 20 is a modified isometric view of a linear hydraulic winch.

[0030] Figure 21 is an isometric view of a culvert towing flange.

[0031] Figure 22 is a linear winch towing device.

[0032] Figure 23 is a top view of extracting crushed CMP with a set of linear winches.

[0033] Figure 24 is section H-H of Figure23.

[0034] Figure 25 is a modified isometric view of extracting crushed CMP
using an excavator.

[0035] Figure 26 is an isometric view of a rammer configured to extract crushed CMP.

[0036] Figure 27 is a modified isometric view of a casing that has replaced a culvert.
DETAILED DESCRIPTION OF THE FIGURES

[0037] Figure 1 shows a typical work site 10 before culvert replacement begins. Surface water gathers on the uphill side of elevated railway 11 on collection plane 12 which extends for an indeterminate distance. Elevated railway 11 is characterized by 2 sloping sides 17 and ballast 18, or stable rock to make it up. As shown, track 14 is made up of ties 16 and rails 15 are located atop the railway 11, however the track 14 could also be a highway or even an elevated pipeline.
Water collected on plane 12 flows through culvert 20 and continues to drain across plane 13.
Culvert 20 in this case has been deemed ready for replacement, either due to impending structural failure or lack of desired flow area.

[0038] Figure 2 is the top view of work site 10 showing culvert 20.
Section line A-A is collinear with the central axis of culvert 20 which conducts surface water from plane 12 through elevated railway 11 to plane 13.

[0039] Figure 3 is section A-A of figure2. Culvert 20 is not sectioned for clarity.
Construction of the elevated section can be understood as virgin material 19 makes up planes 12 and 13 while ballast material 18 was brought in and mounded up to form elevated railway 11.
Culvert 20 would likely have been buried during the addition of ballast 18. As the inside volume of culvert 20 is considerable relative to the cross section of the ballast 18 used to create railway 11, it can be understood that collapse of culvert 20 will cause ballast 18 to fall and therefore drop the elevation of track 14 proximate to culvert 20.

[0040] Figure 4 is a modified isometric view of work site 10 that shows equipment prepared to replace culvert 20, with the effort just beginning. Equipment brought in to accomplish the replacement of culvert 20 include rammer 30 actuated by compressed air fed through hoses 32, casing section 33 into which ram collets 31 are wedged by the nose of rammer 30 and culvert crushing tool 34.

[0041] Figure 5 is a top view of work site 10 that shows equipment prepared to replace culvert 20. Note that section line B-B which runs along the culvert 20 centerline defines figure 6.

[0042] Figure 6 shows much detail regarding the equipment for replacing culvert 20. Figure6 is section B-B of figure5. Note that rammer 30 and culvert 20 are not sectioned for clarity.
Collets 31 are segmented adapters that expand against the inside diameter of steel casing 33. Said collets 31 have a tapered inside diameter that is expanded by the mating taper at the nose of rammer 30. Casing 33 is welded or rigidly attached to the crushing tool 34.
Support 35 is used to maintain coaxial alignment of casing 33 and crusher 34 with culvert 20 to prevent binding or excessive friction which could impact the success of the method. Detail C of the crusher is figure 7.

[0043] Figure 7 is detail C of figure6. Crusher tool 34 is made up of a finite length of steel casing 35. This casing is ideally of the same outside diameter as casing 33, however the wall thickness and therefore inside diameter may be different than casing 33.
Crushing ramp 37 is ideally placed in plural about the inside circumference of casing section 35 and welded or bolted to the tool casing. Ramps 37 will yield the circumference of culvert 20 and deform it into the non-round shape desired to facilitate later extraction from casing 33. The action of the ramps produces very high radial forces that may require reinforcement of tool casing section 35. A steel band 36 is typically placed at the front of a pipe casing installed by a pipe rammer, however it may also be placed at a distance from the front as great as 3.0 pipe diameters back. The band over-expands the local soil and reduces friction on casing 33 as increasing length is installed into the ground. As shown, band 36 can be placed advantageously to provide both reinforcement to contain the radial forces of the crushing ramps as well as reducing friction on the casing 33. The crushing action is a result of the axial drive force by the rammer, through the collets and into the casing string 33. Further the axial force is transmitted through the casing length of the crushing tool and to the ramps 37. Said axial force is converted into radial force as the ramps contact the outer surface of the culvert 20 via the wedge effect of the shallow angle of the ramps 37. The culvert 20 in turn remains stationary relative to railway 11 due to its contact with ballast 18 until such time as the anchoring force of the ballast 18 falls below the axial component of the forces applied by the ramps 37. It has been found that the culvert 20, due to the ribbed surface, remains stationary until the last few feet of the culvert 20 remain to be crushed. At this point the culvert will break loose from the ballast 18 and move axially out of railway 11. So long as the forward end of crushing tool 34 swallows the far end of culvert 20, the roadway structure will not be compromised.

[0044] Figure 8 is a front view of crushing tool 34 having outer casing 35 and steel band 36.
15 Ramps 37 are disposed within the periphery of outer casing 35.

[0045] Figure 9 is a projected view of figure8 with hidden lines visible.
Crushing tool 35 has a forward end 38 displaced some distance (about 1.0 casing diameters) from the start of ramps 37. Said distance to accommodate the anticipated pushout of culvert 20 (not shown) as described in figure 7. Ramps 37 have an optional mounting foot 41 for securing the ramp 37 to the outer 20 casing 35. Steel ring 36 is shown over the area of highest anticipated radial forces; i.e. where the crushing process encounters maximum material strength. Edge 40 is narrow to reduce friction and should be heat treated for hardness or a hard face, friction reducing material should be applied via welding. Rear end 39 would be welded to casing 33 or secured in a manner acceptable for pipe ramming.

[0046] Figure 10 is blade 37 shown in a modified isometric view. Foot 41 shows a slight bend to help it conform to the inside diameter of casing 35. Edge 40 is shown as an angle on the =

face of ramp 37 producing a narrow edge through which the crushing force is applied to the culvert 20 (not shown).

[0047] Figure 11 is a top view of work site 10 that shows equipment in mid process replacing culvert 20. The rammer 34, actuated pneumatically with compressed air via hoses 32, has advanced the casing 33 and therefore the crushing tool 34 along the axis of the culvert 20. To do this, the crushing tool 34 and casing 33 have entered into the ballast 18 making up elevated railway 11. Section line D-D defines the view provided in figure12.

[0048] Figure 12 is section D-D of figure 11. The crushing tool 34 has been advanced through railway 11 via rammer 30 impacts thereby forcibly displacing ballast 18 around the forward end of crushing tool 38, moving it to the outside of crushing tool 34.
Simultaneously, the ramps 37 of crushing tool 34 have deformed the profile of culvert 20 into a shape that provides added annular space to accommodate culvert 20 in its crushed form. Said crushed form allows the material caught between culvert 20 outside diameter and casing 33 inside diameter to have additional volume making it unable to apply frictional loads that transfer from culvert 20 to casing 33; ultimately facilitating removal of culvert 20 from the inside of casing 33. Detail E
makes up figure 13.

[0049] Figure 13 is detail E of figure 12, it best shows the interaction of the crushing tool 34 with the culvert 20 and shows how contact of the ramp 37, specifically edge 40 of ramp 37 will cause culvert 20 to change shape as in transition zone 42 with respect to its periphery. Note in particular the trapped annular material 44 that is tightly squeezed between the culvert 20 outside and the crushing tool 34 casing 35. This material produces significant friction that transfers load, or causes the casing 35 or for that matter casing 33 to 'stick' to the culvert 20. By deforming the culvert 20 outside diameter through the transition 42 and into fully deformed shape 43, said annular material 44 is allowed to occupy a larger volume 45 and the tight squeeze of the material is released, thereby eliminating friction between the culvert 20 and casing 35/33. This friction mechanism is the physical process that kept the prior art form of culvert swallowing from becoming commercially successful. With that said, the addition of the crushing tool to the culvert swallowing process will allow the method to become more easily executed in a successful manner. Note that the form of crush on culvert 20 of transition 42 and final crushed form 43 as represented by figures 12 and 13 is not exact. A more complete and accurate understanding of the deformed shape can be understood by viewing figures 14 and 15.

[0050] Figure 16 shows a steel casing 33 passing through railway 11.
Culvert 20 has been removed as has the rammer, related components and crushing tool. Per the roadway owner specifications, pipe of a longer life than bare steel may be installed in the casing and optionally grouted in.

[0051] Figure 15 is a close approximation of the deformed shape of culvert 20. Assumed to be 36" (though other diameters may be utilized with this method), the outer diameter is represented by dotted line 51, the shape as deformed 50 resulting from running crushing tool 34 (not shown) over the length of culvert 20 is based on maintaining constant tangential length and deformation by the ramps with material spring back. The path of ramp 37 is represented by groove 52.

[0052] Figure 16 is a close approximation of the deformed shape of culvert 20 if a single ramp crushing tool were used. Assumed to be 36", the outer diameter is represented by dotted line 51, the shape as deformed 53 resulting from running a modified crushing tool 34 (not shown) over the length of culvert 20 is based on maintaining constant tangential length and deformation by the ramps with material spring back. The path of a single ramp 37 is represented by groove 52.

[0053] Figure 17 is a top view of work are 10 with lengths of wire rope 63 shown towed in via towing eye 60. The rope is in the annular space between deformed casing 43 and the casing 33.

[0054] Figure 18 is cross section G-G of Figure 17 showing detail of the placement and attachment of rope 63 to the crushing tool 34. Use of such ropes to later remove the crushed culvert 43 is optional. Further, ropes 63 may be disengaged from the crushing tool 34 and attached to the crushed culvert 43 in some manner before the removal process proceeds.

[0055] Figure 19 is an isometric view of a mounting frame 71 to carry multiple linear winches. It includes a tubular mount 71 which is sized to fit closely to the casing 33, mounting flanges 74 and winch pocket 76 and stabilizing tabs 75, all intended to secure a linear winch 80 (see Figure 20). Discharge tube 73 maintains reasonable alignment between the crushed culvert 43 (not shown) and the casing 33 (also not shown). Taper 77 allows the lead end of crushed culvert 43 (not shown) to enter the casing 33 when the culvert extraction process begins.

[0056] Figure 20 is a linear winch 80 used to apply tensile load to wire rope 63. Frame 87 mounts hydraulic cylinders 83 via bolts 89. Pressurized hydraulic oil is supplied and returned through quick disconnects 85 and 86 which in turn flows to control valve 84.
When oil from valve 84 is supplied to the piston end of cylinder 83, rods 81 will extend with up to 15 tons of force and carry rope gripping device 82. When the rods 81 are fully extended, the oil flow is reversed to the rod side of cylinders 83 and the rods will retract releasing the rope 63 (not shown) from the gripping device 82 and simultaneously actuating rope clamping device 88. By repeatedly following this process in a cyclic manner, the wire rope 63 (not shown) will be passed through the linear winch 80 with meaningful force applied to said rope 63.

[0057] Figure 21 is a towing flange 90 configured to apply the towing force of the wire rope 63 (not shown) to the crushed culvert 43 (not shown). It includes a face flange 91 to bear against the culver end, tabs 94 to maintain a centered position of the flange 90 over the end of the culvert 43. Said tabs are sized to fit favorably into the grooves 52 of the crushed culvert 43. Further, ribs 93 to provide structural integrity, a center tube 92 to weld the ribs 93 to and eyes 95 in the tabs 94 to attach the towing rope to.

[0058] Figure 22 is the linear winch assembly 70 comprised of the mounting frame 71 and three linear winches 80. As shown the winch assembly can produce 45 tons of pull on three lengths of wire rope 63 (not shown) coupled to the towing flange 90.

[0059] Figure 23 is a top view of the work area 10 shown with the linear winch 90 mounted on casing 33. Further, winch 90 is shown extracting crushed culvert 43 from casing 33.

[0060] Figure 24 is section H-H of Figure 23. Greater detail of the crushed casing 43 extraction process using winch 90 is shown. Note that the casing 43 and the winch 90 are not sectioned for clarity. Towing flange 90 is centered on the end of crushed culvert 43 and towing lines 43 are secured to the flange 90 and run to the linear winches 80 of winch assembly 70.
Crushed casing 43 is passing through the winch assembly 70 as it is extracted from casing 33.

[0061] Figure 25 is a modified isometric of work area 10 showing crushed casing 43 being extracted from casing 33. As shown, excavator 99 is traversing along plane 13.
Chain 81 and clevis 82 couple the excavator to crushed culvert 43 as tractive effort of the excavator 99 applies towing force to the chain 81 causing the crushed culvert 43 to be pulled from the casing 43.

[0062] Figure 26 shows a percussive system 98 to extract the crushed culvert 43 from casing 33 (neither shown). Pneumatic rammer 34 mounts tapered adapter 97 via its tapered nose. Said adapter 97 has an outer tapered surface 91 as well as a groove 92 both of which are meant to engage the features of the crushed culvert 43, a short section of which is shown. As the profile of crushed culvert 43 includes groove 52 though the exact profile may vary in position and size, therefore the adapter 97 need be able to accommodate this. Use of both taper 91 and tapered groove 92 to engage the ridge formed by groove 52 will make the coupling of percussive forces produced by rammer 34 more likely to be successful. Use of this system 98 will allow the crushed culvert 43 to be extracted from the casing 33 (not shown) by pushing or thrusting it out.
The rammer 34 and adapter 97 need travel with the crushed culvert and traverse the length of the casing to complete the extraction task.

[0063] Figure 27 shows a steel casing 33 passing through roadway 11.
Culvert 20 has been removed as has the rammer, related components and crushing tool. Per the roadway owner specifications, pipe of a longer life than bare steel may be installed in the casing and optionally grouted in.

[0064] While this method as described is intended to be performed solely by plastic deformation of the culvert, using only slight modifications to the ramp, it could achieve the same end result by shearing, cutting or penetrating the material surface longitudinally in either a continuous or non-continuous manner; or by cracking rivets that guarantee the hoop strength of the CMP. An intent of the method is to provide additional annular space by deforming the tangential profile of the culvert. Providing separation of the hoop integrity may make it easier to deform the profile and produce additional annular space for the soil trapped between the casing inside diameter and the culvert outside.

Claims (17)

1. A method wherein an existing hollow pipe comprised of ductile material is deformed in an inward radial direction as it is being swallowed by an equal or larger sized replacement casing.

2. The method of claim 1 wherein the existing pipe is removed from the interior space of the replacement pipe upon the replacement pipe completing traverse of the length of existing pipe to be replaced.

3. The method of claim1 wherein tapered ramps are used to apply radial forces high enough to yield the material of which the existing pipe is comprised of.

4. The method of claim3 wherein the ramps are deployed ahead of the replacement casing.

5. The method of claim 4 wherein the replacement casing is driven by a percussive hammer.

6. A method wherein an existing hollow pipe comprised of ductile material is severed longitudinally as well as deformed in an inward radial direction as it is being swallowed by an equal or larger sized replacement casing.

7. The method of claim 6 wherein the existing pipe is removed from the interior space of the replacement pipe upon the replacement pipe completing traverse of the length of existing pipe to be replaced.

8. The method of claim6 wherein tapered ramps with blades are used to apply radial forces high enough to yield the material of which the existing pipe is comprised of.

9. The method of claim8 wherein the ramps are deployed ahead of the replacement casing.

10. The method of claim 9 wherein the replacement casing is driven by a percussive hammer.

11. The method of claim 7 wherein the existing pipe is removed by towing with a piece of mobile equipment secured to any location on the existing pipe.

12. The method of claim 7 wherein the existing pipe is removed by percussive ramming.

13. The method of claim 6 wherein one or more tensile members are installed simultaneously in the annular space between existing pipe and casing while swallowing.

14. The method of claim 13 wherein the tensile members are secured to the existing pipe and used to pull the existing pipe from the newly installed casing.

15. The method of claim 14 wherein the towing force is supplied via winches secured to the casing.

16. The method of claim 15 wherein the winches are linear winches.

17. The method and apparatus described in the specification and figures, and all equivalent apparatus and methods.