A shield cutterhead and excavation method suitable for soft and hard composite strata

Abstract

A shield cutterhead and excavation method suitable for soft and hard composite strata, the cutterhead comprising a shield cutterhead (1), a cross-shaped main cutter beam (2), an auxiliary cutter beam (3), a center tooth cutter (4), a front roller cutter (5), a cutter (6), an edge roller cutter (7), an edge scraper (8), a fixed tooth cutter (9), a foam nozzle (10), a wear detection knife (11) and a wear-resistant steel plate (12) and other components. The cross-shaped main cutter beam is composed of a first cutter beam, a third cutter beam, a fifth cutter beam and a seventh cutter beam, and the auxiliary cutter beam is composed of a second cutter beam, a fourth cutter beam, a sixth cutter beam and an eighth cutter beam. The method comprises determining the starting torque of the roller cutter, selecting and setting the starting torque of the roller cutter for a soft soil stratum, starting a foam system to spray a foam modifier, and the shield machine pushing the excavation face rock and soil body forward. In the present invention, the cutterhead opening rate reaches 43%, which is particularly suitable for excavation in a typical gravel-sand-mud siltstone composite stratum, and reduces the risk of the cutterhead becoming muddy.

Description

Technical Field

[0001] The invention relates to a shield cutter head and a tunneling method suitable for soft and hard composite strata, belonging to the technical field of tunneling machinery. Background Art

[0002] With the rapid development of my country's economy, the demand for urban underground space development is growing, and a large number of urban tunnel projects have emerged. Among them, the shield method is increasingly widely used in urban tunnel excavation due to its many advantages such as high construction efficiency (it can realize integrated construction of excavation and support), good tunnel forming, and little impact on the surrounding environment. However, when encountering soft and hard composite strata (such as the typical upper soft and lower hard composite strata of upper sand layer and lower mud siltstone in Nanchang), due to the huge difference in stratum conditions, many problems are often induced, among which the more typical ones are: when the disc cutter enters the hard rock stratum from the soft soil stratum, it is easy to knock the cutter due to the large difference in the stiffness of the stratum rock and soil, which will cause the cutter ring to break and the cutter shaft to be damaged; the starting torque of the cutter is different in the rock and soil of different strata, and the cutter is difficult to rotate when it enters the soft soil stratum from the hard rock stratum, resulting in cutter string wear, etc.; the use of a single cutting tool or conventional disc cutter cannot achieve efficient excavation in composite strata. In addition, when the shield machine is excavating in soft and hard composite strata, there are also problems with the stability of the tunnel face in front of the cutterhead and the slag discharge efficiency. Therefore, it is urgent to propose a shield cutterhead and working method that can be applied to soft and hard composite strata, so as to reduce the number of cutter changes during the excavation process, improve the slag discharge efficiency, and ensure the safe and efficient excavation of the shield machine.

[0003] Publication No. CN104060995A discloses a shield cutter structure for composite rock formations with uneven hardness and softness, which includes a heavy cutter, a double-edged center cutter, a single-edged front cutter, a single-edged peripheral cutter, and auxiliary cutters, etc. The auxiliary cutters include front tooth cutters, shovel cutters, and protective cutters. "A shield cutter structure for composite rock formations with uneven hardness and softness" does not consider the impact of the cutter starting torque on the shield tunneling efficiency, that is, when the starting torque is large, the conventional cutter is difficult to rotate when entering the soft soil (gravel and sand) formation from the hard rock formation due to insufficient friction, thereby inducing string wear; and when the starting torque is adjusted too small, the overall stiffness of the cutter decreases, and the impact force on the hard rock formation and the position where the hard-soft composite interface changes stiffness is large, which can easily cause the cutter to loosen or even be damaged. In addition, the cutterhead opening rate in this patent is 20%-30%. When the excavation stratum is a muddy siltstone stratum with a high clay content, it cannot be guaranteed that the debris can enter the soil bin smoothly, thereby inducing mud cake to form on the cutterhead. Summary of the invention

[0004] The purpose of the present invention is to address the main deficiencies of the above-mentioned prior art and to provide a shield cutter head and excavation method suitable for soft and hard composite strata.

[0005] The technical solution implemented by the present invention is as follows: a shield cutter head suitable for soft and hard composite formations, including a shield cutter head, a cross-shaped main cutter beam, an auxiliary cutter beam, a center tooth cutter, a front hob, a cutter, an edge hob, an edge scraper, a fixed tooth cutter, a foam nozzle, a wear detection knife, a wear-resistant steel plate and other TBM components.

[0006] Four Y-shaped auxiliary blade beams are distributed on the diagonal lines between the cross-shaped main blade beams, and the cross-shaped main blade beams and the auxiliary blade beams constitute the load-bearing structure of the shield cutter head; the cross-shaped main blade beam is composed of the first blade beam, the third blade beam, the fifth blade beam and the seventh blade beam, and the auxiliary blade beam is composed of the second blade beam, the fourth blade beam, the sixth blade beam and the eighth blade beam.

[0007] Eight center tooth cutters are evenly installed side by side in the central part of the cross-shaped main knife beam; 20 17-inch front rollers are installed on the cross-shaped main knife beam, with five evenly installed on each main knife beam; cutting knives are arranged before and after the rolling traces of the front rollers, with a total of 56 cutting knives distributed and installed on both sides of the cross-shaped main knife beam; six foam nozzles are set on the beams of the cross-shaped main knife beam and the auxiliary knife beam.

[0008] The auxiliary tool beam is a Y-shaped structure with the Y-mouth facing outward, and is provided with 37 fixed tooth cutters and 7 17-inch edge rollers; 8 pairs of edge scrapers with a height of 145 mm are arranged at the end of the cross-shaped main tool beam; a wear detection knife is arranged on one auxiliary tool beam for real-time monitoring of tool wear.

[0009] The center tooth cutter has a blade height of 175 mm and a blade spacing of 90 mm; the center tooth cutter can effectively reduce the large torque caused by conventional fishtail cutters under similar formation conditions, thereby reducing shield energy consumption and improving excavation efficiency.

[0010] The front hob has a blade height of 175 mm and a blade spacing of 100 mm; the front hob is a specially made high-hardness columnar toothed hob.

[0011] The columnar insert tooth hob is composed of a columnar insert tooth hob and alloy column teeth; the columnar insert tooth hob is a circular ring structure, and a plurality of alloy column teeth of the same height are evenly inlaid around the outer edge of the columnar insert tooth hob.

[0012] The cutter has a height of 140 mm and a cutter spacing of 150 mm; the cutter ensures efficient excavation of the shield in soft and hard composite strata through the combined effect of the front roller rolling hard rock and the cutter cutting soft soil; the 56 cutters are installed and distributed as follows: 24 cutters are arranged at equal intervals radially from the inside to the outside on the third cutter beam and the seventh cutter beam; since the central part of the first cutter beam and the fifth cutter beam has been arranged with a central tooth cutter, the 4 cutters are arranged at equal intervals radially from the inside to the outside; the outer 2 cutters are arranged closely, for a total of 24; 2 cutters are symmetrically arranged at the central parts of the auxiliary cutter beams, the second cutter beam, the fourth cutter beam, the sixth cutter beam, and the eighth cutter beam, for a total of 8.

[0013] Through the combined rolling and cutting action of the front roller cutter and the cutter, efficient excavation in composite formations is achieved. When excavating in hard rock formations, due to the low single-cycle penetration, the excavation rate is mainly controlled by the front columnar tooth roller rolling and breaking the rock, and the cutter assists in cutting and removing the broken rock and soil residue at the tunnel face, and enters the soil bin through the cutterhead opening; when excavating in soft formations, for typical gravel and sand formations, due to the high single-cycle penetration, the sand and soil cutting action of the cutter is fully mobilized, which can effectively cut and remove the residue and complete each cycle of excavation.

[0014] The fixed tooth cutters and edge roller cutters are distributed on four auxiliary knife beams, and the fixed tooth cutters are symmetrically arranged on the auxiliary knife beams and the edge of the cutter disc, wherein: 7 fixed tooth cutters are symmetrically arranged on the second knife beam and the sixth knife beam respectively; the fixed tooth cutters at the fourth knife beam and the eighth knife beam are cancelled due to the arrangement of 2 foam nozzles and 1 wear detection knife, and the remaining positions are arranged the same as the second knife beam and the fourth knife beam, 6 fixed tooth cutters are arranged on the fourth knife beam and 5 fixed tooth cutters are arranged on the eighth knife beam; 12 fixed tooth cutters are arranged at equal intervals on the edge of the cutter disc; a total of 37 fixed tooth cutters are arranged.

[0015] Seven edge rollers are symmetrically arranged at the edges of the four auxiliary cutter beams near the cutter disc, with two symmetrically arranged at the second, sixth and eighth cutter beams respectively, and one at the fourth cutter beam; over-excavation tooth cutters are arranged at symmetrical positions to effectively control the over-excavation amount in soft and hard composite formations.

[0016] The foam nozzles are installed and distributed as follows: one foam nozzle is symmetrically arranged on both sides of the central tooth cutter on the third blade beam 3 of the cross-shaped main blade beam, and one foam nozzle is arranged at the outer edge end of the third blade beam; one foam nozzle is arranged on the fourth blade beam of the auxiliary blade beam, and two foam nozzles are arranged on the eighth blade beam.

[0017] A shield cutterhead excavation method suitable for soft and hard composite strata is as follows:

[0018] (1) Based on the preliminary geological survey data of the specific project, determine the soil distribution and specific physical and mechanical properties when the shield tunnel passes through the soft and hard composite strata.

[0019] (2) The starting torque of the cutter should be determined according to the characteristics of the stratum to be penetrated. When excavating in sandy and gravel strata, the starting torque setting value of the cutter should not be greater than 20 Nm. When excavating in hard rock strata such as muddy siltstone, the starting torque setting value of the cutter should be within the range of 25-40 Nm.

[0020] (3) When penetrating a composite stratum with soft upper and hard lower layers, select and set the cutter starting torque for the soft soil stratum.

[0021] (4) Start the foam system and spray the foam improver in front of the cutter disc through the foam nozzle.

[0022] (5) The shield cutter head starts to rotate, the screw conveyor is started and the propulsion mode is started. The shield moves forward to excavate the rock and soil at the tunnel face.

[0023] The physical and mechanical property indicators include the saturated uniaxial compressive strength UCS of the rock layer, the rock mass integrity coefficient RQD value, the measured average standard penetration hammer number N of the sandy layer, the particle grading, the clay content, as well as important parameters such as cohesion c and internal friction angle φ.

[0024] The beneficial effect of the present invention is that, by setting the starting torque of the cutter suitable for soft soil formations in advance, the present invention can ensure that the cutter rotates effectively when excavating in soft soil formations, thereby preventing the cutter ring from being worn out; when the cutter repeatedly rolls and cuts rock and soil in soft and hard composite formations, the alloy column teeth on the outside of the cutter ring can protect the ring and improve wear resistance, thereby preventing the disc cutter from knocking or being severely worn when repeatedly passing through the interface between soft and hard rock formations; in addition, 6 foam nozzles are arranged on the cutter disc, which can add foaming agent in real time according to the slag discharge situation and the properties of the slag, reduce tool wear through slag improvement, avoid cutter disc mud, ensure slag discharge effect and face stability, and improve the excavation efficiency of the shield in composite formations.

[0025] The front cutter and edge cutter adopted by the present invention are both specially made columnar insert cutters. When excavating in rock formations, the high-hardness alloy columnar inserts not only improve the efficiency of the cutter penetrating and breaking rocks, but also protect the cutter ring from severe wear. When excavating in soft and hard composite formations, when the cutter rolls through the soft and hard transition interface, the cutter ring will bear the impact force generated by the huge stiffness difference of the formation, and the columnar inserts improve the impact resistance of the cutter ring to a large extent, effectively avoiding the undesirable conditions of knocking the cutter or even the cutter ring being damaged. When entering soft formations, due to the embedded bite effect between the columnar inserts and the face rock and soil during the rolling process, the cutter is more likely to roll the face rock and soil due to the rotation of the entire cutter disc under the same starting torque, thereby effectively avoiding the eccentric wear of the cutter ring induced by the locking of the cutter mud or the inability of the cutter and the face to rotate normally, reducing the number of cutter changes and improving the excavation efficiency.

[0026] The cutterhead opening rate of the present invention reaches 43%, which is much higher than the 20%-30% of similar cutterheads. The 43% opening rate setting is particularly suitable for typical gravel sand-mud siltstone composite formations, because the lower hard rock formation is mud siltstone, which has a very high clay content, and the resulting slag has high cohesion, large lumps, and is not easy to flow. The 43% opening rate setting can effectively ensure that the rock and soil cut off from the face in front of the cutterhead enters the soil bin and is then discharged by the screw conveyor, reducing the risk of the cutterhead getting muddy.

[0027] The excavation cutter disc device of the present invention has a simple structure, the used parts are easy to process, the auxiliary facilities are technologically mature, and it has high feasibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a schematic diagram of the planar layout of the cutterhead;

[0029] Figure 2 Schematic diagram of the toothed hob cutter ring in the cutter disc;

[0030] Figure 3 This is a flow chart of the principle of using the cutter disc;

[0031] In the figure, 1 is the shield cutter head; 2 is the cross-shaped main cutter beam; 3 is the auxiliary cutter beam; 4 is the center tooth cutter; 5 is the front hob; 5-1 is the insert hob blade; 5-2 is the alloy column tooth; 6 is the cutter; 7 is the edge hob; 8 is the edge scraper; 9 is the fixed tooth cutter; 10 is the foam nozzle; 11 is the wear detection knife; 12 is the wear-resistant steel plate. DETAILED DESCRIPTION

[0032] like Figure 1 and Figure 2 As shown, the present embodiment is a shield cutter head suitable for soft and hard composite formations, mainly including a shield cutter head 1, a cross-shaped main cutter beam 2, an auxiliary cutter beam 3, a center tooth cutter 4, a front hob 5, an inlaid tooth hob blade 5-1, an alloy column tooth 5-2, a cutter 6, an edge hob 7, an edge scraper 8, a fixed tooth cutter 9, an over-digging tooth cutter 9-1, a foam nozzle 10, a wear detection knife 11, a wear-resistant steel plate 12 and other necessary parts not listed.

[0033] The main working principle of the shield cutterhead in this embodiment, which is suitable for soft and hard composite strata, is as follows:

[0034] The main load-bearing structure of the shield cutter head 1 is composed of a cross-shaped main cutter beam 2 and an auxiliary cutter beam 3.

[0035] Eight center tooth cutters 4 with a cutter height of 175 mm are installed at the central part of the cross-shaped main cutter beam 1, and the cutter spacing is set to 90 mm, which can effectively reduce the large torque caused by conventional fishtail cutters under similar formation conditions, thereby reducing the energy consumption of the shield and improving the excavation efficiency.

[0036] Twenty 17-inch front rollers 5 are installed on the cross-shaped main cutter beam 2, with a cutter height of 175mm and a cutter spacing of 100mm; cutters 6 are arranged before and after the rolling trace of the front rollers 5, totaling 56, with a cutter height of 140mm and a cutter spacing of 150mm. The combined effect of the front rollers 5 rolling hard rock and the cutters 6 cutting soft soil ensures efficient excavation of the shield in soft and hard composite strata.

[0037] 22 fixed tooth cutters 9 are arranged on the auxiliary cutter beam 3 to assist in cutting the rock and soil; 7 17-inch edge roller cutters 7 are arranged on the auxiliary cutter beam 3 to break the rock and soil at the edge of the cutter disc to form an effective over-excavation gap.

[0038] Eight pairs of edge scrapers 8 with a height of 145 mm are arranged at the end of the main cutter beam 2 to assist the front roller cutter 5 and the cutter 6 in breaking the rock and soil of the tunnel face.

[0039] The opening rate of the cutter disc 1 is set to 43%, so as to ensure that when encountering a stratum with a high clay content, the slag can be effectively discharged to avoid the cutter disc 1 being sticky and the cutter being caked with mud; 6 foam nozzles 10 are arranged on the cutter disc 1, and foaming agents can be added in real time according to the slag discharge situation and the properties of the slag, so as to ensure the slag discharge effect and improve the shield excavation efficiency through slag improvement; a wear monitoring knife 11 is installed on the auxiliary cutter beam for real-time monitoring of tool wear; 10mm and 50mm thick wear-resistant steel plates 12 are respectively set on the cutter disc panel and the periphery to protect the shield cutter disc.

[0040] The steps of using a shield cutterhead for tunneling in a soft-hard composite stratum according to this embodiment are as follows:

[0041] (1) Based on the preliminary geological survey data of the specific project, determine the soil distribution and specific physical and mechanical properties when the shield tunnel passes through the soft and hard composite strata.

[0042] (2) The starting torque of the cutter should be determined based on the characteristics of the stratum being penetrated. In particular, the starting torque setting value of the cutter should not be greater than 20 Nm during excavation in sandy and gravel strata. The starting torque setting value of the cutter should be within the range of 25-40 Nm during excavation in hard rock strata such as muddy siltstone.

[0043] (3) When penetrating a composite stratum with soft upper and hard lower layers, select and set the cutter starting torque for the soft soil stratum.

[0044] (4) Start the foam system and spray the foam improver in front of the cutter disc through the foam nozzle.

[0045] (5) The shield cutter head starts to rotate, the screw conveyor is started and the propulsion mode is started. The shield moves forward to excavate the rock and soil at the tunnel face.

[0046] The use effect of this embodiment is as follows:

[0047] During the construction of the shield tunnel section between Shangshagou Station and Qifeng Road Station in Section 3 of Metro Line 4 in a certain city, an earth pressure balance shield tunneling was selected, and the cutterhead structure and tunneling method described in the present invention were adopted. The shield machine achieved stable tunneling in the gravel sand-mud siltstone composite stratum, with an average tunneling speed of 470 rings / month, of which the highest tunneling speed reached 20 rings / day. During the tunneling process, it was originally planned to stop the machine and change the cutter once. Because the shield machine and the cutterhead tool were in good working condition, the tool change was cancelled during the actual tunneling. After the penetration, the cutterhead tool was checked, and no adverse phenomena such as cutterhead mud and severe eccentric wear of the tool occurred.

Claims

1. A shield cutterhead suitable for soft and hard composite strata, comprising a shield cutterhead, a cross-shaped main cutter beam, an auxiliary cutter beam, a center tooth cutter, a front hob, a cutter, an edge hob, an edge scraper, a fixed tooth cutter, a foam nozzle, a wear detection knife, and a wear-resistant steel plate, characterized in that: Four Y-shaped auxiliary blade beams are distributed on the diagonal line between the cross-shaped main blade beams, and the cross-shaped main blade beams and auxiliary blade beams constitute the load-bearing structure of the shield cutter head; the cross-shaped main blade beam is composed of the first blade beam, the third blade beam, the fifth blade beam and the seventh blade beam, and the auxiliary blade beam is composed of the second blade beam, the fourth blade beam, the sixth blade beam and the eighth blade beam; 8 center tooth cutters are evenly installed side by side at the center of the cross-shaped main blade beam; 20 17-inch front hobs are installed on the cross-shaped main blade beam, each Five knives are evenly installed on the main knife beam; cutters are arranged before and after the front hob rolling trace, with a total of 56 cutters, which are distributed and installed on both sides of the cross-shaped main knife beam; 6 foam nozzles are arranged on the cross-shaped main knife beam and the auxiliary knife beam; the auxiliary knife beam is a Y-shaped structure with the Y-mouth facing outward, and 37 fixed tooth knives and 7 17-inch edge hobs are arranged on the auxiliary knife beam; 8 pairs of edge scrapers with a height of 145mm are arranged at the end of the cross-shaped main knife beam; a wear detection knife is arranged on the auxiliary knife beam; The front hob has a blade height of 175 mm and a blade spacing of 100 mm; the front hob is a specially made high-hardness columnar toothed hob; The cutter has a height of 140 mm and a cutter spacing of 150 mm. The cutter ensures efficient excavation of the shield in soft and hard composite strata by the combined effect of the front toothed hob rolling hard rock and the cutter cutting soft soil. The 56 cutters are installed and distributed as follows: 24 cutters are arranged at equal intervals radially from the inside to the outside of the third cutter beam and the seventh cutter beam; since the central part of the first cutter beam and the fifth cutter beam has been arranged with a central toothed cutter, the four cutters are arranged at equal intervals radially from the inside to the outside; the two outer cutters are arranged closely, for a total of 24; two cutters are symmetrically arranged at the central parts of the second cutter beam, the fourth cutter beam, the sixth cutter beam, and the eighth cutter beam of the Y-shaped auxiliary cutter beam, for a total of 8; The fixed tooth cutters and edge hobs are distributed on four auxiliary cutter beams; The fixed toothed knives are symmetrically arranged on the Y-shaped auxiliary knife beam and the edge of the knife disc, wherein: 7 fixed toothed knives are symmetrically arranged on the second knife beam and the sixth knife beam respectively; the fixed toothed knives at the fourth knife beam and the eighth knife beam are cancelled because 2 foam nozzles and 1 wear detection knife are arranged on the fourth knife beam and the eighth knife beam, and the arrangement of the remaining positions is the same as that of the second knife beam and the fourth knife beam, 6 fixed toothed knives are arranged on the fourth knife beam, and 5 fixed toothed knives are arranged on the eighth knife beam; 12 fixed toothed knives are arranged at equal intervals on the edge of the knife disc; a total of 37 fixed toothed knives are arranged; Seven edge rollers are symmetrically arranged near the edge of the cutter disc on the four auxiliary cutter beams, of which two are symmetrically arranged on the second cutter beam, the sixth cutter beam, and the eighth cutter beam, and one is arranged on the fourth cutter beam; over-digging tooth cutters are arranged at symmetrical positions to effectively control the over-digging amount in soft and hard composite strata; The columnar insert tooth hob is composed of a columnar insert tooth hob and alloy column teeth; the columnar insert tooth hob is a circular ring structure, and a plurality of alloy column teeth of the same height are evenly inlaid around the outer edge of the columnar insert tooth hob.

2. The shield cutterhead suitable for soft and hard composite strata according to claim 1, characterized in that: The blade height of the central toothed blade is 175 mm, and the blade spacing is set to 90 mm.

3. The shield cutterhead suitable for soft and hard composite strata according to claim 1, characterized in that: The foam nozzles are installed and distributed as follows: one foam nozzle is symmetrically arranged on both sides of the central tooth cutter on the third blade beam of the cross-shaped main blade beam, and one foam nozzle is arranged at the outer edge end of the third blade beam; one foam nozzle is arranged on the fourth blade beam of the auxiliary blade beam, and two foam nozzles are arranged on the eighth blade beam.

4. The shield cutterhead suitable for soft and hard composite strata according to claim 1, characterized in that: The excavation method of the shield cutterhead suitable for soft and hard composite strata is as follows: (1) Based on the preliminary geological survey data of the specific project, determine the soil layer distribution and specific physical and mechanical property indicators when the shield tunnel passes through the soft and hard composite strata; (2) The starting torque of the cutter should be determined according to the characteristics of the stratum to be penetrated. When excavating in sandy and gravel strata, the starting torque of the cutter should not be set greater than 20 Nm. When excavating in muddy and siltstone strata, the starting torque of the cutter should be set within the range of 25-40 Nm. (3) When the cutter is passing through a composite stratum with soft upper and hard lower layers, select and set the cutter start torque for the soft soil stratum; (4) Start the foam system and spray the foam modifier in front of the cutter disc through the foam nozzle; (5) The shield cutter head starts to rotate, the screw conveyor is started and the propulsion mode is started. The shield moves forward to excavate the rock and soil at the tunnel face.

5. The shield cutterhead suitable for soft and hard composite strata according to claim 4, characterized in that: The specific physical and mechanical property indicators include the saturated uniaxial compressive strength UCS of the rock layer, the rock mass integrity coefficient RQD value, the measured average standard penetration hammer number N of the sandy layer, the particle grading, the clay content, and the important parameters of cohesion c and internal friction angle φ.

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