A geotechnical engineering net pressure shield construction device and construction method thereof

Abstract

The invention discloses a geotechnical engineering net-pressure drag shield construction device and a construction method thereof, comprising a front shield and a rear shield frame arranged at the rear side thereof, wherein the rear shield frame and the front shield can both move along the excavation direction and can be independently lifted and lowered; the front shield is used for temporarily or permanently supporting the tunnel roof formed in the current working step; the top of the rear shield frame is used for laying an anchoring net, and the rear shield frame is used for lifting the anchoring net to the top of the tunnel to permanently support the tunnel roof. The device solves the problem that the shield of an underground engineering tunneling machine may damage the surrounding rock structure or that an empty top is easily formed during the net laying operation after the shield body, so that the continuous operation of temporary support and anchor support without empty top can be realized during the construction of the tunnel with anchor support, thereby achieving the purpose of intrinsic safety.

Description

Technical Field

[0001] The invention relates to the field of mechanized construction of underground engineering excavation, and in particular to a geotechnical engineering net pressure shield construction device and a construction method thereof. Background Art

[0002] Roof protection during underground tunnel construction is a major issue related to production safety. To achieve inherent safety, temporary support must be immediately provided when exposed rock is formed after rock excavation, and at the same time, no empty roof will appear during the transition from temporary support to permanent support. Most of the existing mechanized excavation construction devices do not have temporary support devices when they are designed. There are also many studies and tests on temporary support devices. The design basis is to use the short stabilization time after the surrounding rock excavation to complete the anchor support. Although it can meet production in most cases over the years, it does not comply with the relevant regulations of the geotechnical engineering construction specifications and cannot meet the requirements of inherent safety production.

[0003] At present, the most commonly used tunnel boring machine in coal mines is the cantilever type. Due to the design flexibility of the cutting part of this type of tunnel boring machine, it is impossible to design temporary support to follow the tunneling. Therefore, in most cases, it only serves the two functions of rock breaking and transportation, and anchor support is mostly done manually or with other equipment. If temporary support is used after a cycle of rock breaking and tunneling, it will have a great impact on the construction, and the temporary support itself is not safe. This construction method cannot achieve simultaneous tunneling and anchoring.

[0004] The anchor drill can realize the mechanization of tunneling and anchoring at the same time. This kind of tunneling equipment has no temporary support or the temporary support is integrated with the anchor drill in a small frame. In addition, the distance from the cutting part to the anchor support position generally requires at least two to four steps of empty top for smooth construction. The reason why this large empty top distance can be implemented for a long time is that there is no personnel working in the empty top area at the front end of the anchor drill, so there is no personnel safety problem. Therefore, although this kind of tunneling machine is highly efficient, it cannot meet the construction of broken surrounding rock tunnels.

[0005] Another type of construction equipment is a TBM shield machine designed for particularly soft strata. During the construction process of this type of equipment, the shield shell can block the surrounding rock in real time, which can meet the requirements of immediate excavation and immediate protection. However, the shield of this type of equipment is only suitable for particularly soft soil layers or underground projects with prefabricated structures for permanent support or particularly hard rock conditions. For particularly soft soil layers, they can be compacted and solidified under the pressure of the shield support, which is conducive to the implementation of temporary support after the shield shell is moved forward, or the use of pipe segments as permanent support can smoothly transition with the shield support during permanent support construction. Although this type of equipment has a shield, its support function often destroys the ordinary surrounding rock structure, making it easier for the surrounding rock to fall off after the shield shell passes, which is dangerous. It is only suitable for tunnel construction using prefabricated pipe segments. Therefore, it is still difficult for underground engineering tunnels supported by anchor rods to achieve anchor rod construction without empty top after the shield body passes.

[0006] To sum up, whether it is manual temporary support, mechanized temporary support or shield construction equipment with temporary support function, although it can seem to solve the problem of temporary support to a certain extent, in underground projects using anchor support technology, none of them solves the problem of continuous transition between temporary support and anchor support. Summary of the invention

[0007] In view of the problem that after the underground engineering excavation and rock breaking are completed, it is impossible to support the exposed surrounding rock in time and to implement anchor support without evacuating the temporary support, the present invention provides a geotechnical engineering mesh pressure shield construction device and an anchor support construction method thereof, which can realize continuous non-empty top support and excavation of the tunnel, greatly improving the excavation efficiency while ensuring safe construction.

[0008] The present invention is achieved through the following technical solutions:

[0009] A geotechnical engineering net pressure drag shield construction device, comprising a front shield and a rear shield frame arranged front and rear along the excavation direction, wherein the rear shield frame and the front shield can both move along the excavation direction and can be independently raised and lowered;

[0010] The front shield is arranged at the rear end of the cutting device at the working face and moves synchronously. The front shield includes a support body and a shield plate arranged on the top thereof. The front end of the shield plate is adjacent to the top of the cutting device, and the rear end of the shield plate extends toward the rear shield frame. The shield plate is used to temporarily support the tunnel roof formed by the current excavation of the cutting device. The rear shield frame is used to support the laid anchor net on the bottom surface of the shield plate, and the anchor net is located between the shield plate and the rear shield frame. The anchor net is used to permanently support the tunnel roof.

[0011] The front shield and the rear shield frame move alternately along the excavation direction. After the front shield moves forward, the anchoring net contacts the tunnel roof, and the rear end of the front shield is always located between the anchoring net and the tunnel roof.

[0012] Preferably, a shield dragging body is arranged on the top of the support body, a shield plate is arranged on the top of the shield dragging body, and a moving device is arranged on the bottom of the support body.

[0013] Preferably, the shield body and the shield plate are fixedly connected or detachably connected, and an anchor hole is provided on the shield plate;

[0014] When the shield plate and the shield body are fixedly connected, the shield plate is used to temporarily support the tunnel roof;

[0015] When the shield plate and the shield dragging body are detachably connected, the shield plate is used to provide permanent support for the tunnel roof.

[0016] Preferably, the shield plate is composed of a plurality of sub-shield plates, which are sequentially arranged on the drag shield body along the width direction of the tunnel, and each sub-shield plate can move individually or in groups along the excavation direction.

[0017] Preferably, a strip is provided at one end of the shield plate close to the rear shield frame, and the strip shield is located between the anchor net and the top plate of the tunnel during excavation.

[0018] Preferably, the rear shield frame includes a shield frame body and support legs arranged at the bottom, a moving device is arranged at the lower end of the support legs, and the top of the shield frame body is used to apply a supporting force to the laid anchoring net.

[0019] Preferably, the shield frame body includes a plurality of rear shield frame transverse beams arranged at intervals, the axial direction of the rear shield frame transverse beams is arranged perpendicular to the excavation direction, a plurality of rear shield frame running beams are arranged on the plurality of rear shield frame transverse beams, and the area between two adjacent rear shield frame running beams forms an anchoring channel.

[0020] Preferably, a telescopic shield is provided in the shield frame body, and the telescopic shield can extend to one side of the front shield.

[0021] Preferably, a folding shield is provided at the end of the shield frame body or the end of the telescopic shield, and the folding shield is located on a side close to the front shield. The end of the folding shield is hinged to the end of the shield frame body or the end of the telescopic shield, and the folding shield can rotate along the hinged end.

[0022] A construction method of a geotechnical engineering net pressure shield construction device comprises the following steps:

[0023] Step 1: The cutting device excavates the tunnel, and the front shield moves synchronously with the cutting device. The front shield forms a temporary support for the tunnel roof formed by the cutting device, and the end of the front shield is located between the tunnel roof formed in the previous step and the anchoring net;

[0024] Step 2: Lay the anchor net at the bottom of the shield plate, and the back frame supports the top of the anchor net on the bottom surface of the shield plate;

[0025] Step 3: The front shield moves forward along the excavation direction, and the rear end of the front shield is gradually pulled out from between the anchoring net and the tunnel roof until the anchoring point is exposed, and then the anchor rod construction is carried out. The anchor rod and the anchoring net form a permanent support for the tunnel roof;

[0026] The end of the shield plate of the front shield is located between the anchoring net and the top plate of the tunnel during the movement;

[0027] Step 4: Repeat steps 1-3 until the predetermined tunnel excavation length is completed.

[0028] Compared with the prior art, the present invention has the following beneficial technical effects:

[0029] The invention provides a geotechnical engineering mesh pressure and shield construction device, which relates to the field of mechanized construction of underground engineering excavation. In view of the temporary support and temporary empty top in the anchor support process of the anchor support tunnel, which may form a safety hazard, the front shield is used to form temporary or permanent support for the tunnel top according to the rock stability of the newly excavated tunnel top, and the rear shield frame lifts the anchor mesh and forms permanent support for the tunnel top formed in the previous step. The mesh pressure and shield support structure combined with the front shield and the rear shield frame solves the problem that the shield of the underground engineering tunneling machine may damage the surrounding rock structure or that an empty top is easily formed during the net laying operation after the shield body, so that the continuous operation of temporary support and anchor support can be achieved during the construction of the anchor support tunnel, thereby achieving the purpose of intrinsic safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A schematic structural diagram of the shield-dragging construction device of the present invention;

[0031] Figure 2 A schematic structural diagram of the integrated front drag shield of the present invention;

[0032] Figure 3 A schematic diagram of the structure of the front drag shield with a strip at the end of the present invention;

[0033] Figure 4 Figure 3 Schematic diagram of the center front drag shield structure;

[0034] Figure 5 A schematic structural diagram of the split front drag shield and rear drag shield of the present invention;

[0035] Figure 6 An exploded view of the split front towing shield and rear towing shield of the present invention;

[0036] Figure 7 A schematic structural diagram of a sliding front drag shield according to the present invention;

[0037] Figure 8 Figure 7 Construction status diagram of the middle front towing shield;

[0038] Fig. 9 A schematic diagram of the driving structure of the sliding front drag shield of the present invention;

[0039] Fig.10 The detachable anchor shield mesh pressure and shield dragging construction device of the present invention;

[0040] Fig.11 The shield plate of the present invention has a reserved anchor hole;

[0041] Fig.12 A schematic structural diagram of the telescopic backing frame of the present invention;

[0042] Fig.13 The present invention has a back support frame with a foldable frame;

[0043] Fig.14 The telescopic foldable back support frame of the present invention;

[0044] Fig.15 The shield-dragging construction device of the present invention has a foldable frame;

[0045] Fig.16 The invention discloses a construction device for arc-shaped multi-block sliding shield plates, a mesh pressure and drag shield;

[0046] Fig.17 Structural diagram of a shield-dragging construction device and a tunneling device according to Embodiment 1 of the present invention;

[0047] Fig.18 Structural diagram of a shield-dragging construction device and a tunneling device according to Embodiment 5 of the present invention;

[0048] Fig.19 Structural diagram of a shield-dragging construction device and a tunneling device according to Embodiment 7 of the present invention;

[0049] Fig. 20 The invention discloses a construction method of a front-drag shield construction device for geotechnical engineering.

[0050] Explanation of the accompanying reference numerals: 1 front shield, 101 shield supporting body, 102 supporting body, 103 sub-shield plate, 104 shield plate, 105 strip shield, 107 shield plate with reserved anchor holes; 108 shield supporting body; 109 arc-shaped sub-shield; 110 driving device; 2 rear shield frame, 201 rear shield frame running beam, 202 rear shield frame transverse beam, 203 rear shield frame legs, 204 telescopic shield, 205 folding shield, 206 telescopic folding shield; 207 longitudinal supporting beam; 208 arc-shaped transverse beam. DETAILED DESCRIPTION

[0051] The present invention will be further described in detail below in conjunction with the accompanying drawings, which are intended to explain the present invention rather than to limit it.

[0052] Example 1

[0053] See also Figure 1-20 A geotechnical engineering mesh pressure shield construction device comprises a front shield 1 and a rear shield frame 2 arranged front and rear along the excavation direction. The rear shield frame 2 and the front shield 1 can both move along the excavation direction and can be independently lifted and lowered. The front shield is arranged at the rear end of the cutting device of the excavation device and moves synchronously with the cutting device. The rear shield frame 2 is located at the rear end of the front shield 1.

[0054] During the tunnel excavation process, the cutting device excavates the face, the front shield 1 is located at the top rear end of the cutting device and moves synchronously, forming a temporary support for the tunnel roof formed by the cutting device excavation, and the rear shield frame 2 is used to support the anchor net laid at the bottom of the front shield, the anchor net is located between the front shield and the rear shield frame, and the front shield and the rear shield frame move alternately along the excavation direction. After the front shield moves forward, the anchor net contacts the tunnel roof, and the end of the front shield is always located between the anchor net and the tunnel roof. The anchor net is used to permanently support the tunnel roof.

[0055] The above-mentioned net-pressure and shield-dragging construction device, during construction, the front shield 1 moves along the excavation direction, and can provide real-time temporary support for the exposed rock mass (tunnel roof) on the top formed by the excavation of the cutting device, so as to avoid the collapse problem caused by unstable rock mass and improve the safety of excavation. An anchoring net is laid at the bottom of the front shield and supported by a rear shield frame. When the next excavation step is started, the front shield 1 moves along the excavation direction with the cutting device, so that the front shield is gradually pulled out of the anchoring net, and the anchoring net is tightly attached to the rock mass of the tunnel roof. Finally, the anchoring net is fixed to the tunnel roof by anchor rods to form a permanent support, and then the anchoring net is continued to be laid at the bottom of the front shield and supported by the rear shield frame. Repeating the above process can realize continuous support and excavation of the tunnel without empty top, which greatly improves the excavation efficiency while ensuring safe construction.

[0056] See also Figure 6 The rear shield frame 2 includes a shield frame body and a rear shield frame leg 203 arranged at the bottom thereof. The plurality of rear shield frame legs are distributed in a rectangular shape. The shield frame body is arranged on the top of the rear shield frame legs. An anchoring channel is arranged on the shield frame body, which is used to pass the upper end of the anchor rod through the anchoring channel to fix the anchoring net on the rock mass to form a permanent support. The rear shield frame legs are a telescopic structure, and the shield frame body is raised or lowered by the rear shield frame legs of the telescopic structure.

[0057] The rear shield frame legs 203 include inner legs and outer legs which are sleeved with each other, the lower end of the outer legs is connected to a base which is arranged on a mobile device, a hydraulic drive device is arranged in the base, the lower end of the inner legs is connected to the hydraulic drive device, and the upper end of the inner legs is connected to the shield frame body.

[0058] The hydraulic drive device is a hydraulic cylinder, a piston rod of the hydraulic cylinder is connected to the lower end of the inner leg, and the extension and retraction of the piston rod can drive the shield frame body to rise and fall, and the anchoring net is used to be laid on the top of the shield frame body.

[0059] The shield frame body includes two rear shield frame transverse beams 202 arranged at intervals, the axial direction of the rear shield frame transverse beams 202 is arranged perpendicular to the axial direction of the excavation direction, and a plurality of rear shield frame strike beams 201 are arranged on the two rear shield frame transverse beams 202. The plurality of rear shield frame strike beams 201 are arranged at intervals along the excavation width direction, and the area between two adjacent rear shield frame strike beams 201 forms an anchoring channel. The anchor rod passes through the gap between the two adjacent rear shield frame strike beams 201 to fix the anchoring net to the rock mass of the tunnel roof.

[0060] See also Figure 2 The front shield 1 includes a shield dragging body 101, a shield plate 104 and a support body 102; the shield dragging body 101 is arranged on the top of the support body 102, one end of the shield plate 104 is connected to the top of the shield dragging body, and the other end extends toward the rear shield frame 2, and the cross-section of the shield supporting body 101 along the excavation direction is triangular. When the front shield 1 moves, the shield supporting body 101 is used to remove a small amount of rock on the moving path.

[0061] The support body includes a plurality of support legs, the lower ends of which are connected to a moving device. The structure of the support legs is the same as that of the rear shield frame legs and will not be described in detail. During operation, the front shield 1 is controlled to move along the excavation direction by the moving device, and then the shield body is controlled to rise or fall by the hydraulic rod, so that the shield plate 104 temporarily supports the top plate of the tunnel.

[0062] See also Figure 3 and 4 The end of the shield plate 104, that is, the end close to the rear shield frame, is provided with a strip shield 105, which is located between the anchor net laid in the previous step and the tunnel roof. When the front shield moves, the support legs make the shield plate 104 drop to a certain distance, adjust the pressure between the shield plate 104 and the tunnel roof, so that the shield plate 104 and the tunnel roof are in a zero pressure contact state, and then the front shield 1 is moved along the excavation direction by the moving device. The length of the shield plate 104 is greater than each The length of an excavation step, when the current shield 1 moves one excavation step, the strip shield 105 is located between the anchor mesh laid in the previous step and the rock mass, and then the shield plate 104 is lifted up through the supporting legs and maintains a certain pressure with the tunnel roof, so that the shield plate forms a temporary support for the tunnel roof of the current step. At the same time, because the strip shield is located between the anchor mesh and the tunnel roof, it can increase the bearing capacity of the shield plate, so that the temporary support formed by the shield plate can form a stable support for the tunnel top.

[0063] See also Fig.17 The geotechnical engineering net pressure shield construction device is installed on a tunnel boring machine, and the tunnel boring machine includes a main body 300, a power transfer machine 400 and a cutting part 600;

[0064] An operating platform is formed on the top of the main body 300, with the excavation direction as the front. The power transfer machine 400 is arranged at the rear of the main body 300. The power transfer machine 400 and the main body 300 are movably connected to the shovel conveyor 500 through an interactive lifting mechanism; the front end of the shovel conveyor 500 is movably connected to the cutting part 600, the front shield 1 and the rear shield frame 2 are arranged on the operating platform, and the crawler walking mechanism at the bottom of the main body drives the cutting part 600 forward or backward to realize tunnel excavation. The front shield 1 is arranged at the front end of the operating platform and moves synchronously with the operating platform, and the rear shield frame is located behind the front shield 1.

[0065] See also Fig. 20 The following is a detailed description of a construction method of a geotechnical engineering net pressure shield construction device provided by the present invention, which includes the following steps:

[0066] Step 1: During excavation, the front shield 1 moves synchronously with the cutting device of the excavation device, and the front end of the shield plate 104 of the front shield is located at the top of the rear end of the cutting device, and the shield plate 104 of the front shield forms a temporary support for the tunnel roof formed by excavation.

[0067] During the movement of the front shield 1, the height of the shield plate 104 is controlled by telescopic supporting legs, so that the shield plate 104 maintains a 0 pressure device with the tunnel roof, that is, a contact state, and can move along the excavation direction while playing a supporting role. When the excavation of the current work step is completed, the shield plate 104 is lifted by telescopic supporting legs, and a certain pressure is applied to the tunnel roof, thereby realizing temporary support for the tunnel roof formed by excavation.

[0068] Step 2: laying an anchoring net at the bottom of the shield plate 104 of the front shield, and the rear shield frame 2 supports the top of the anchoring net on the bottom surface of the shield plate 104;

[0069] In this step, an anchoring net is supported at the bottom of the shield plate of the front shield by artificial support, and then the rear shield frame is moved to the bottom of the anchoring net, and the shield frame body is lifted by telescopic support legs to support the anchoring net.

[0070] Alternatively, an anchoring net is laid on the top of the shield frame body of the rear shield frame 2 , and then the shield frame body is lifted by telescopic supporting legs, and the anchoring net is pressed onto the bottom of the shield plate 104 .

[0071] Step 3: excavate the next step, the front shield 1 moves synchronously with the cutting state, and the rear end of the front shield is gradually withdrawn from between the anchoring net and the tunnel roof. When the anchoring point position of the anchoring net is exposed, anchor rod construction is carried out to make the anchoring net form permanent support for the tunnel roof;

[0072] Specifically, before excavation, the supporting force of the rear shield frame on the front shield frame is adjusted to facilitate the movement of the front shield. During the movement of the front shield, the shield plate can be gradually pulled out of the anchor net to expose the anchor point. Anchor rods are constructed through the anchor point, so that the anchor net forms permanent support for the tunnel roof.

[0073] Secondly, when the front shield 1 moves forward one step, the end of the shield plate 104 is located between the anchoring net laid in the previous step and the tunnel roof, which can avoid the appearance of an empty top on the tunnel roof and realize continuous construction work without an empty top.

[0074] Step 4, repeat step 2, that is, lay the anchor net at the bottom of the shield plate of the front shield, and splice the edge of the anchor net with the edge of the anchor net laid in the previous step to form a whole, and the rear shield frame supports the top of the anchor net on the bottom surface of the front shield to maintain a 5kN balanced support force;

[0075] Step 5: Repeat steps 3 and 4 until the predetermined tunnel excavation length is completed.

[0076] The construction method disclosed in the present invention solves the problem of the shield of the underground engineering tunnel boring machine damaging the surrounding rock structure or the empty top defect after the shield body and before the anchor net support, and eliminates the empty top phenomenon under any circumstances. The technical method and construction equipment of the present invention can achieve the safety problem of temporary support to protect the surrounding rock from falling off in the shortest time, and can also achieve the transition of temporary support in one-time implementation and continuous construction of anchor support, thereby achieving intrinsically safe and rapid construction.

[0077] Example 2

[0078] See also Fig.11 In Example 2, a telescopic shield 204 is also provided in the rear shield frame 2, and the telescopic shield is used to expand the permanent support range.

[0079] The telescopic shield 204 includes a plurality of telescopic shield running beams, the rear shield frame running beam 201 is a hollow beam, the plurality of telescopic shield running beams are respectively arranged in the plurality of hollow beams, one end of the plurality of telescopic shield running beams 201 are all located outside the hollow beams, and the plurality of telescopic rods are connected by the telescopic shield transverse beam to form a whole.

[0080] The telescopic shield is connected to a telescopic shield driving device, which includes an elastic reset device and a hydraulic cylinder. The hydraulic cylinder is fixed to the rear end of the shield frame body. The piston rod of the hydraulic cylinder is connected to at least one telescopic shield running beam. The telescopic shield is driven to extend or retract through the movement of the piston rod. One end of the elastic reset device is hinged to the telescopic shield transverse beam, and the other end is hinged to the rear end of the shield frame body, that is, the end away from the front shield. The elastic reset device is a spring. When the piston rod is retracted, the spring plays an auxiliary role and drives the telescopic shield to retract.

[0081] The construction method of the construction device with the telescopic shield is the same as steps 1 to 3 of the construction device without the telescopic shield, except for step 4, which is as follows:

[0082] Step 3: During the next excavation step, the front shield moves synchronously with the cutting state, and the rear end of the front shield is gradually withdrawn from between the anchoring net and the tunnel roof, so that the anchoring point of the anchoring net faces the tunnel roof, and then the anchor rod construction is carried out, so that the anchoring net forms a permanent support for the tunnel roof;

[0083] Step 4: Adjust the height of the rear shield frame, and then extend the telescopic shield so that the telescopic shield is located at the bottom of the front shield, lay the anchor net on the telescopic shield and lift the rear shield frame, press the laid anchor net between the shield plate of the front shield and the telescopic shield, and then connect the currently laid anchor net with the adjacent anchor net.

[0084] Step 5: Adjust the lifting pressure of the front shield, excavate the next step, and gradually withdraw the rear end of the front shield from between the anchoring net and the tunnel roof, so that the anchoring point of the anchoring net is facing the tunnel roof, and then carry out anchor rod construction, so that the anchoring net forms a permanent support for the tunnel roof excavated in the previous step;

[0085] Step 6: Repeat steps 3 and 5 until the predetermined tunnel excavation length is completed.

[0086] A telescopic shield is installed on the rear shield frame. When the rear shield frame does not move, the telescopic shield is used to complete one step of tunnel roof support, thereby improving construction efficiency.

[0087] Example 3

[0088] See also Fig.12 In Example 3, a folding shield 205 is provided at the end of the rear shield frame 2, one end of the folding shield is hinged to the rear shield frame running beam 201 of the rear shield frame 2, and the other end is a free end and extends in the excavation direction. The folding shield is connected to the rear shield frame leg through an oblique driving device, and the oblique driving device is used to drive the folding shield to rotate along the hinged end. When in the folded state, the folding shield is in a vertical state, and when laying the net, the folding shield is in a horizontal state.

[0089] The folding shield 205 includes a plurality of longitudinal rods, one end of each longitudinal rod is hinged to the end of the rear shield frame running beam 201, and the other ends of the plurality of longitudinal rods are connected by a cross rod. The gap between the two longitudinal rods forms an anchoring channel, and the anchor rod fixes the anchoring net laid on the folding shield through the anchoring channel.

[0090] The oblique driving device is a hydraulic push rod, one end of which is hinged to the rear shield frame and the other end is hinged to the folding shield. When the tunnel roof is permanently supported, the piston rod is extended to rotate the folding shield to a horizontal state, and then the anchoring net is laid on it and lifted up. After the anchoring is completed, the folding shield is rotated to a vertical state by the hydraulic push rod.

[0091] The construction method of the folding shield is similar to that of the telescopic shield, except for step 4, which is as follows:

[0092] Step 4: lay the anchoring net on the folding shield 205, rotate the folding shield 205 to a horizontal state through the hydraulic push rod, and locate it at the bottom of the front shield 1, press the laid anchoring net between the shield plate 104 of the front shield and the folding shield, and then connect the currently laid anchoring net with the adjacent anchoring net.

[0093] Step 5: Reduce the lifting pressure of the front shield, excavate the next step, and gradually withdraw the rear end of the front shield from between the anchoring net and the tunnel roof, so that the anchoring point of the anchoring net is facing the tunnel roof, and then carry out anchor rod construction, so that the anchoring net forms a permanent support for the tunnel roof excavated in the previous step;

[0094] Step 6: Repeat steps 3 and 5 until the predetermined tunnel excavation length is completed.

[0095] The construction method rotates the folding shield to a horizontal state through an oblique driving device, and lays an anchoring net between the front shield and the folding shield, and presses the anchoring net against the bottom of the front shield through the oblique driving device, and then moves the front shield a distance of the folding shield, at which time the anchoring net contacts the rock mass, and then fixes the anchoring net through anchor rods to form permanent support, and forms continuous support for the rock mass between the front shield and the rear shield frame through the folding shield, thereby improving the safety of construction; secondly, the folding shield is installed on the rear shield frame, and when the rear shield frame does not move, the telescopic shield is used to complete one step of tunnel roof support, thereby improving the construction efficiency.

[0096] Example 4

[0097] See also Fig.13 In Example 4, the folding shield 205 and the telescopic shield 204 are combined, and the folding shield 205 is hinged at the end of the telescopic shield 204 to form a telescopic folding shield 206. The hinged end of each longitudinal rod is provided with a hinge seat, and the hinge seat is fixedly connected to the end cross bar of the telescopic shield. The gap between the two longitudinal rods forms an anchoring channel, and the anchor rod fixes the anchoring net laid on the folding shield through the anchoring channel, and the telescopic shield moves synchronously with the folding shield.

[0098] The rear shield frame running beam is a hollow beam, and a slide groove extending along its axial direction is arranged at the bottom of at least one rear shield frame running beam 201. A downwardly extending fixed plate is arranged at the bottom of the telescopic shield running beam of the telescopic shield, and the fixed plate is located in the slide groove. When the telescopic shield reciprocates, the upper end of the fixed plate moves in the slide groove, one end of the push rod of the folding shield is connected to the fixed plate, and the other end is hinged to the end of the folding shield. When the telescopic shield is extended, the folding shield and the push rod move synchronously, and then the folding shield is rotated to a horizontal state by the push rod.

[0099] The construction method of the telescopic folding shield 206 combines the construction methods of the telescopic shield of Example 2 and the folding shield of Example 3, and is specifically as follows:

[0100] The rear shield supports the anchor net of the current work step, and after the anchor construction is completed, the excavation of the next work step is carried out. After the front shield moves forward, the supporting pressure of the rear shield is adjusted. Without moving the rear shield, the telescopic shield and the folding shield move to the bottom of the front shield, and the anchor net is laid on the telescopic shield. The front shield moves forward to continue to provide temporary support for the tunnel roof of the next work step, and then anchor construction is carried out on the laid anchor net.

[0101] Then, according to the construction method of Example 3, an anchoring net is laid on the folding shield and rotated to a horizontal level, the front shield moves forward to continue to temporarily support the tunnel roof of the next step, and then the anchoring net is anchored.

[0102] The telescopic folding shield 206 combines a telescopic shield and a folding shield. When the rear shield frame remains stationary, the telescopic shield and the folding shield are moved in sequence to achieve continuous permanent support of the tunnel roof in two steps, further improving construction efficiency.

[0103] Example 5

[0104] See also Figure 5-8 and Fig.18 In Example 5, the shield plate 104 of the front shield is composed of a plurality of sub-shield plates 103. The shield drag body 101 is a rectangular plate, and a slide groove along the excavation direction is arranged inside it. A plurality of sliders arranged in parallel are arranged in the slide groove. A plurality of sub-shield plates are respectively arranged on the top of the plurality of sliders, and the end sliders of the sub-shield plates are fixed. The other end of the sub-shield plate 103 extends in the direction of the rear shield frame 2 for overlapping the top of the rear shield frame 2. A driving device is provided at the bottom of the supporting shield body for driving each sub-shield plate to slide independently in the slide groove in the excavation direction, or for moving a plurality of sub-shield plates 103 in groups.

[0105] The driving device is a hydraulic cylinder, the cylinder body of which is fixedly connected to the bottom of the drag shield body 101, the end of the piston rod of the hydraulic cylinder is connected to the end of the slider and is located outside the drag shield body, and the slider is driven to move by the telescopic movement of the piston rod of the hydraulic cylinder, thereby realizing the independent movement or grouped movement of each sub-shield.

[0106] During excavation, the stability of the top rock mass is very poor. The front shield is lifted to form temporary support for the rock mass through the spliced ​​shield plates. Then the rear shield frame is moved to the bottom of the shield plate, and an anchor net is laid on the top surface of the rear shield frame. The rear shield frame is lifted to make the anchor net contact with the bottom surface of the shield plate. According to the on-site conditions of the rock mass, multiple sub-shields are moved one by one in the excavation direction through multiple hydraulic cylinders. Every time a sub-shield is moved, the anchor net in that area is fixed to the rock mass, effectively solving the problem of unstable rock support.

[0107] For example, during construction, the sub-shield is first extended to its longest state through the hydraulic cylinder, and then the front shield is moved synchronously with the tunneling device. Even if the front shield provides temporary support for the tunnel roof formed by real-time excavation, when the excavation reaches a working step, each sub-shield is moved forward piece by piece along both sides of the shield plate toward the center. Each sub-shield can also be moved piece by piece from the center to both sides to decompose the shield plate into multiple sub-shield plates. By moving each sub-shield plate, the tunnel roof is divided into multiple areas along the width direction and anchored one by one, which greatly improves the stability of the rock mass.

[0108] Example 6

[0109] See also Fig.10 and 11 In another embodiment 6, the structure of the front shield is optimized as follows:

[0110] The shield plate 104 is detachably connected to the shield supporting body 101, and anchor holes are provided on the shield plate to form a reserved anchor hole shield plate 107. When the stability of the rock mass is very poor, the reserved anchor hole shield plate 107 is used for permanent support. The reserved anchor hole shield plate 107 is lifted to the rock mass position to provide temporary support for the rock mass. Since the stability of the rock mass is poor, it is easy to cause tunnel collapse. At this time, the reserved anchor hole shield plate is used as an anchoring net, and the shield plate is fixed to the rock mass through the anchor holes to form permanent support, thereby reducing the risk of tunnel collapse.

[0111] The shield support body is provided with a horizontal slot, and the reserved anchor hole shield plate 107 is inserted in the slot. A fixing plate is provided at the bottom edge of the slot, and a threaded hole is provided on the fixing plate. The reserved anchor hole shield plate 107 is connected to the fixing plate by bolts. When the reserved anchor hole shield plate 107 is anchored to the rock mass, the shield plate can be separated from the shield support body by removing the bolts, and then a new shield plate 104 is installed on the shield support body 101.

[0112] Example 7

[0113] See also Fig.16 and 19 In Example 7, the front shield 1 and the rear shield frame 2 are both arc-shaped, which are suitable for tunnels with arc-shaped tops. The arc-shaped rear shield frame 2 includes an arc-shaped transverse beam 208, and the two ends of the arc-shaped transverse beam 208 are respectively connected to the rear shield frame legs 203. A plurality of spaced longitudinal support beams 207 are arranged between the two arc-shaped transverse beams 208. The remaining structure is the same as that of the above-mentioned rear shield frame and will not be repeated.

[0114] The front shield 1 includes an arc-shaped shield support body 108 and a plurality of arc-shaped sub-shields 109. The arc-shaped shield support body is provided with slots, and the plurality of arc-shaped sub-shields are inserted into and fixed in the slots. The net pressure shield construction device for arc-shaped tunnels provided in this embodiment is the same as the construction method of embodiment 1, and will not be described in detail.

[0115] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A geotechnical engineering net pressure shield construction device, characterized in that: It comprises a front shield (1) and a rear shield frame (2) arranged front and rear along the excavation direction, wherein the rear shield frame (2) and the front shield (1) are both movable along the excavation direction and capable of being raised and lowered independently; The front shield (1) is arranged at the rear end of the cutting device on the working surface and moves synchronously, the front shield (1) comprises a support body (102) and a shield plate (104) arranged on the top thereof, the front end of the shield plate (104) is adjacent to the top of the cutting device, and the rear end of the shield plate (104) extends in the direction of the rear shield frame, the shield plate (104) is used to temporarily support the tunnel roof formed by the current excavation of the cutting device; the rear shield frame (2) is used to support the laid anchoring net on the bottom surface of the shield plate (104), and the anchoring net is located between the shield plate (104) and the rear shield frame (2), and the anchoring net is used to permanently support the tunnel roof; The front shield (1) and the rear shield frame (2) move alternately along the excavation direction, the anchoring net contacts the tunnel roof after the front shield (1) moves forward, and the rear end of the front shield (1) is always located between the anchoring net and the tunnel roof; A shield dragging body (101) is arranged on the top of the support body (102), a shield plate (104) is arranged on the top of the shield dragging body (101), and a moving device is arranged on the bottom of the support body; The shield plate (104) is composed of a plurality of sub-shield plates (103) spliced ​​together, the plurality of sub-shield plates are sequentially arranged on the drag shield body (101) along the tunnel width direction, and each sub-shield plate (103) can move individually or in groups along the excavation direction; The rear shield frame (2) comprises a shield frame body and support legs arranged at the bottom, a moving device is arranged at the lower end of the support legs, and the top of the shield frame body is used to apply a supporting force to the laid anchoring net.

2. A geotechnical engineering net pressure shield construction device according to claim 1, characterized in that: The shield body (101) and the shield plate (104) are fixedly connected or detachably connected, and the shield plate is provided with an anchor hole; When the shield plate (104) and the shield dragging body are fixedly connected, the shield plate (104) is used to temporarily support the top plate of the tunnel; When the shield plate (104) and the shield dragging body are detachably connected, the shield plate (104) is used to permanently support the tunnel roof.

3. A geotechnical engineering net pressure shield construction device according to claim 1, characterized in that: A strip shield (105) is provided at one end of the shield plate (104) close to the rear shield frame. During excavation, the strip shield (105) is located between the anchoring net and the top plate of the tunnel.

4. A geotechnical engineering net pressure shield construction device according to claim 1, characterized in that: The shield frame body comprises a plurality of rear shield frame transverse beams (202) arranged at intervals, the axial direction of the rear shield frame transverse beams (202) being arranged perpendicular to the excavation direction, a plurality of rear shield frame running beams (201) being arranged on the plurality of rear shield frame transverse beams (202), and an anchoring channel being formed in the area between two adjacent rear shield frame running beams (201).

5. A geotechnical engineering net pressure shield construction device according to claim 1, characterized in that: A telescopic shield (204) is arranged in the shield frame body, and the telescopic shield (204) can extend to one side of the front shield (1).

6. A geotechnical engineering net pressure shield construction device according to claim 5, characterized in that: A folding shield (205) is provided at the end of the shield frame body or the end of the telescopic shield (204); the folding shield (205) is located on a side close to the front shield (1); the end of the folding shield (205) is hinged to the end of the shield frame body or the end of the telescopic shield (204); and the folding shield (205) is capable of rotating along the hinged end.

7. A construction method for a geotechnical engineering net pressure shield construction device according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step 1: The cutting device excavates the tunnel, and the front shield (1) moves synchronously with the cutting device. The front shield (1) forms a temporary support for the tunnel roof formed by the excavation of the cutting device, and the end of the front shield (1) is located between the tunnel roof formed in the previous step and the anchoring net; Step 2: laying an anchoring net on the bottom of the shield plate (104), and the rear shield frame (2) supports the top of the anchoring net on the bottom surface of the shield plate; Step 3: The front shield moves forward along the excavation direction, and the rear end of the front shield is gradually pulled out from between the anchoring net and the tunnel roof until the anchoring point is exposed, and then the anchor rod construction is carried out. The anchor rod and the anchoring net form a permanent support for the tunnel roof; When the front shield (1) is moving, the end of the shield plate (104) is located between the anchoring net and the tunnel roof; Step 4: Repeat steps 1-3 until the predetermined tunnel excavation length is completed.

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