A PROCESS AND APPARATUS TO MOVE AND FORM UNDERGROUND PASSAGES IN SOIL

Abstract: The apparatus to move and form a passage or space in the soil comprises squeezing means (6) for squeezing the soil and thrust means (9, 11) for producing a thrust force to advance said squeezing means (6) to move and form a passage or space in the soil.

Description: The invention relates to an apparatus for forming a space in soil, comprising squeezing means, a thrust means and a prime mover connected in series. The DE-B 120 99 74 shows an apparatus for forming a space in loose soil, the conical front end of which being provided with spiral fins for loosening the soil. The known apparatus is moved forward by hydraulic means, while the front end is rotated. An apparatus of the generic kind is known from the DE 30 15 381 A1. The squeezing means of the known apparatus is integral with a rotating front spiral thrust means. A further spiral thrust means is connected to the front spiral thrust means, the thread of which having a pitch opposite to the pitch of the front spiral means. In order to move the apparatus forward, the thrust means are driven in counter-rotation such that the anti-torque moment exerted by the soil is compensated to a large extent. The known apparatus is adapted to form a space in a loose soil. However, if the soil resistance is high, forward movement of the apparatus is very slow, as the soil is further compressed by the squeezing means. Furthermore, a very strong prime mover is required for moving the apparatus through the compressed soil. Where the soil substance or the density of the soil varies from place to place within the length of the known apparatus, the counter-rotated spiral blades separately fixed on two rods in series would be blocked to stop revolving as there is a difference of resistance exerted between the two spiral blades. Additionally the two counter-rotating spiral blades cut the soil such that two slots crossing each other are provided. Therefore small pieces of cross-cut soil will collapse. Thus, the efficiency of the known apparatus is low especially if it is used for forming a space in soil having a high resistance. Starting out from the apparatus of the generic kind, it is the problem underlying the invention to provide a simple apparatus permitting efficient forming of a space in soil having a high resistance, the shape of the space being controllable. This problem is solved in that the squeezing means includes vibratory means for reducing the resistance of the soil, in that the squeezing means is connected to the thrust means by an enclosed connection means including a thrust receiving means engaged with the thrust means and hydraulic jack means connecting the thrust receiving means and the squeezing means, in that a vibra-tion absorbing means is interposed between the squeezing means and the connection means, and in that the thrust means comprises a thrust rod with spiral blades fixed on the thrust rod which is driven by the prime mover. The problem is also solved in that the squeezing means includes vibratory means for reducing the resistance of the soil, in that the squeezing means is connected to the thrust means by an enclosed connection means including a thrust receiving means engaged with the thrust means and hydraulic jack means connecting the thrust receiving means and the squeezing means, in that a vibration absorbing means is interposed between the squeezing means and the connection means, and in that the thrust means comprises a hydraulic thrust means, the plunger rod of the hydraulic thrust means being engaged with the thrust receiving means of the connection means, and locking means for preventing a backward movement of the apparatus. The vibration of the vibratory means loosens the contact between the sqeezing means and the soil in the close neighbourhood of the squeezing means when the apparatus is moved forward. "Close neighbourhood" means a distance of several millimeters to about hundreds of centimeters from the squeezing means, so as to lower the soil resistance exerted on the apparatus while it is moved forward by the thrust means. The vibration absorbing means is interposed between the squeezing means and the connection means in order to lower the vibration exerted on the connection means. The shape of the space can be controlled by changing the orientation of the squeezing head by means of the hydraulic jacks. As in the first apparatus of the invention the spiral blades are only fixed to the thrust rod only a single threaded cut slot is provided in the wall of the made passage. As small pieces of cut soil will not collapse the quality of the made passage is high. In a preferred embodiment of the apparatus, the connection means comprises control means for controlling the vibratory means and the thrust means so as to orientate the movement and the passage to a determined direction. For example, employing a gyroscope or other means such as a three-dimensional sensor and a micro-computer to give orders to actuators to effect consequent actions, namely to automate orientation control. In addition, it is also possible to control the process of vibratory squeezing and regulate the amplitude of vibration, so as to limit the extent of the contact of soil in the neighbourhood compressed by the vibratory means. The vibration means advantageously is an eccentric means driven by a motor. If it is desired to form a passage close to the ground surface, preferably the front part of the squeezing means is substantially wedge-shaped or cone-shaped. Using a wedge-shaped squeezing-head, the vibration motion should be in a direction perpendicular to the direction of forward motion, but only substantially parallel to the plane of the ground surface. The vibratory motion of the vibratory means may be actuated by various means such as eccentric, electromagnetic, hydraulic or pneumatic devices, etc., provided they are powerful enough to induce the necessary amplitude and frequency on the squeezing means. In order that the vibratory apparatus may move smoothly in the subterranean soils, the following fundamental requirements should be fulfilled: a) The vibratory amplitude should not be under a certain limit. For instance, when a body sinks under vibration, the magnitude of the amplitude should exceed that when the apparatus starts to sink so as to continue the sinking. The initial magnitude of the amplitude required depends on the vibration frequency, soil property and the bulk and shape of the apparatus. Generally, the lower the vibration frequency and the larger the cross-section of the body, the larger the sinking amplitude will be. The more the vibration amplitude exceeds the initial sinking amplitude, the higher the sinking speed will be. b) The vibratory frequency should be higher than the destructive frequency of the soil. When a body vibrates in the soil, the frictional resistance of the soil to the surface of the body begins to break down under the action of a certain frequency and vibratory force so that that body may move freely. c) The thrusting force to push the apparatus forward should be able to overcome the encountered resistance of the soil to the front end of the apparatus. As the apparatus is moved by means of a vibratory squeezing mode, no large amount of excavated soil is produced and subsequently needs to be removed. The process and the apparatus provided by the present invention permit an economical and effective producing of space in soil with a high resistance. Therefore the apparatus will be able , by means of vibratory squeezing, to advance forward simultaneousley forming a passage or space in subterranean layer. As a result of controlling the orientation by proper means if necessary, the passage mode may be vertical, horizontally or even inclined. By repeating the process of vibratory squeezing in a passage already made, a larger passage or space can be expanded by means of the same process but more powerful apparatus. In this way, it is possible to excavate a very much larger subterranean space , such as a cellar, an underground garage or the like, if the process to be repeated is controlled in a sideways horizontal direction with respect to the original passage mode. Embodiments of the invention are further explained by means of drawings: Fig. 1 schematically shows a first embodiment of an apparatus for forming a space in soil; Fig. 2 shows the cross-section II-II of fig. 1; Fig. 3 shows the cross-section III-III of fig. 1, Fig. 4 is a sectional view of a connection means of the apparatus shown in fig. 1, Fig. 5 is a sectional view of the front end of the apparatus shown in Fig. 1 Fig. 6 shows the cross-section VI-VI of fig. 5, Fig. 7 is a sectional view of the rear end of the apparatus shown in fig. 1, Fig. 8 schematically shows the movement of the apparatus of fig. 1; Fig. 9 shows a second embodiment of the apparatus for forming a space in soil; Fig. 10 schematically shows a wedge-shaped squeezing means. As shown in fig. 1 to 7, the first embodiment of the apparatus for forming a space in soil comprises a squeezing means 6 at its front end, fixed in the soil with a set of stabilizing fins 7 to prevent it from revolving. The stabilizing fins 7 also present a certain guiding action. The vibratory squeezing means 6 is connected to a thrust rod 9 by connection means 8, comprising a corrugated pipe. A power-line passes through the corrugated pipe to supply electric power to a vibratory means enclosed in the squeezing means 6 and composed of an electric motor 13 and eccentrics 14. The motor 13 rotates the eccentrics 14 to produce circumferential vibration in the squeezing means 6. A damping mechanism is fitted into the inner chamber of the tail part of the squeezing means 6, which comprises a ball-bearing 15, ball-bearing races 16, damping material 17 and a bearing plate 18. The bearing plate 18 is to take the thrust force from the thrust rod 9 or thrust transmitted through the connection means 8. The bearing plate 18 receives thrust force from the thrust rod 9 transmitted via a universal joint 22 of the connection means 8 and then transfers this thrust to the entire squeezing means 6 through the rolling balls of the ball-bearing 15. The rolling balls, due to their rolling action, can attenuate the vibration produced by the vibratory means at the front when transferring the thrust to the bearing plate 18 and thus play the role of a damper. On the bearing plate 18, there are dowel pins 19 which fit into pinholes 20 on the tail retaining plate of the squeezing means 6. Damping material, such as sponge rubber 21, is fixed in between the dowel pin 19 and the pin hole 20. The thickness of the damping materials 17 and 21 should be larger than the vibration amplitude of the vibratory squeezing means. The action of the dowel pin 19 and the pin hole 20 is to prevent the bearing plate 18 from relative rotary displacement with the vibratory squeezing means and thus ensure a sensor of a control means 25 to deliver precision locating signals. The control means 25 is disposed in the connection means 8 and composed of three-dimensional sensors, micro-computers and actuators, such as a set of hydraulic jacks 23, so as to realize the three-dimensional control of the squeezing means 6. Spiral blades 10 are fixed to the thrust rod which will screw into the soil. It is important that the total area of the blades 10 in contact with soil should be enough to give axial thrust while moving forward, and to ensure that the shear stress and pressure against the soil are less than the limit shear strength and limit compression strength of the soil so that there will be no "slip-idling" of the spiral blades 10 to cure and to loose the thrust. The one end of the thrust rod 9 is connected to an electric motor 27 through a speed variator 28. The electric motor 27 and the speed variator 28 are locked together by means of a pin and may be disassembled to facilitate transportation. The electric motor 27 and the speed variator 28 may also be connected by a universal joint to transmit power to the thrust rod 9 and to rotate it. The rotation of the spiral blade 10 in the soil will drive the whole apparatus forward. In order to prevent the housing 11 of the electric motor 27 from turning in the reverse direction when the electric motor 27 is driving the thrust rod 9, a set of stabilizing guide fins 12 is fixed to the surface of the motor housing 11. A certain portion of the lateral surface of the stabilizing guide fins 12 tucking in the soil, will suffice to prevent the reversal of the revolution. It is important that the shear stress and compressive stress by the guide fins 12 against the soil must be less than the shear strength and the compressive strength of the soil there, otherwise slippage will occur. One thing that has to be pointed out is that the apparatus will start the operation in the soil with the help of a booster thrusting means a hydraulic jack or the like (not shown in the diagram) so that the spiral blades 10 and the stabilizing guide fin 12 at the front end of the squeezing means 6 or the thrust rod 9 may enter and screw into the soil, and then the apparatus begins its vibratory squeezing and moves forward under the reaction of the soil against the spiral fin 12. The second embodiment of the apparatus for forming a space in soil which is shown in Fig. 9, has a vibratory squeezing means 35 similar in construction to that of the first embodiment. This second embodiment further comprises a stabilizing guide fin 36, a connection means 37, a front locking mechanism 38, a front locking blade 39, a cylinder 40 of a hydraulic device, a hydraulic plunger rod 41, a rear locking mechanism 42, a rear locking blade 43 and a corrugated pipe 44. The thrusting means of the second embodiment is hydraulic with at least one hydraulic cylinder 40 or a set of evenly arranged hydraulic actuators. The plunger rod 41 joining the plunger is connected to the front locking mechanism 38 in which the retractable front locking blade 39 is fitted. On the back of the cylinder 40 the rear locking mechanism 42 is fitted which has the retractable rear locking blades 43 of large area, too. When the locking blade 39 in the front is pulled in and when the locking blades 43 of the rear are sticking out, the hydraulic plunger rod 41 acts forward and exerts force on the vibratory squeezing means so that it will vibrate and push forward at the same time. At this moment, the hydraulic cylinder 40 of the prime mover is prevented from retracting backward by resistance produced by the rear locking blades 45 being inserted in the soil. When the front locking blade 39 is sticking out and the rear locking blades 43 are retracted, the hydraulic plunger rod 41 will retract to the hydraulic actuator. Then the resistance produced by the front locking blade 39 which is inserted in the soil prevents the vibratory squeezing means 35 from retreating, and the hydraulic actuator moves forward over a distance of one plunger stroke. In this way, one cycle of all these motions will bring the apparatus as a whole to move a one-stroke distance. The above motion cycle can be programmed and controlled by the micro-computer in the connection means 37. As an alternative embodiment of the present invention the apparatus may have a trailer 31 comprising an expanding vibratory squeezing section and attached to the tail part of the apparatus by a connection rope 32 (see fig. 8). The trailer 31 has a vibratory means inside and can be used to enlarge a tunnel 33 already squeezed out and to form an expanded passage 34 having a cross-section other than a circle according to the shape of the trailer 31, such as a horseshoe, ellipse or rectangle. In contrast to the vibratory squeezing means, placed at the front, the vibratory amplitude and frequency may be set higher without limit. The trailer 31 is located behind the spiral fin of the thrusting section such that the limit shear strength and compressive strength of soil in contact with the spiral fin is not affected. During the forward movement of the apparatus the squeezing resistance may be diminished in this way to a large extent and the squeezing effect may be increased. Fig. 10 shows different views of the wedge-shaped squeezing means in vibration direction 45 and motion direction 46, respectively.

Claims: An apparatus for forming a space in soil, comprising squeezing means (6, 35), a thrust means (9, 40) and a prime mover (27) connected in series, characterized in that the squeezing means (6, 35) includes vibratory means (13, 14) for reducing the resistance of the soil in that the squeezing means (6, 35) is connected to the thrust means (9, 40) by an enclosed connection means (8, 37) including a thrust receiving means (26) engaged with the thrust means (9, 40) and hydraulic jack means (23) connecting the thrust receiving means (26) and the squeezing means (6, 35), in that a vibration absorbing means (17) is interposed between the squeezing means (6) and the connection means (8), and in that the thrust means comprises a thrust rod (9) with spiral blades (10) fixed on the thrust rod (9) which is driven by the prime mover (27). An apparatus for forming a space in soil, comprising squeezing means (6, 35), a thrust means (9, 40) and a prime mover (27) connected in series, characterized in that the squeezing means (6, 35) includes vibratory means (13, 14) for reducing the resistance of the soil in that the squeezing means (6, 35) is connected to the thrust means (9, 40) by an enclosed connection means (8, 37) including a thrust receiving means (26) engaged with the thrust means (9, 40) and hydraulic jack means (23) connecting the thrust receiving means (26) and the squeezing means (6, 35), in that a vibration absorbing means (17) is interposed between the squeezing means (6) and the connection means (8), and in that the thrust means comprises a hydraulic thrust means (40), the plunger rod (41) of the hydraulic thrust means (40) being engaged with the thrust receiving means (26) of the connection means (37), and locking means (42) for preventing a backward movement of the apparatus. An apparatus according to claim 1 or 2, characterized in that the connection means (8, 37) comprises control means for controlling the vibratory means (13, 14) and the thrust means (9, 40). An apparatus according to one of the preceeding claims, characterized in that the vibration means is an eccentric means (14) driven by a motor (13). An apparatus according to one of the preceeding claims characterized in that the front part of the squeezing means (35) is substantially wedge-shaped or cone-shaped.

Inventors: SHANDA, TIAN
Applicants: SHANDA, TIAN
Application year: 1986
Main classification: E21B7
IPC codes: E21B7