A tunneling method for a stratum with developed cross-section confined fissure water based on pressure relief and water stoppage

Abstract

The present invention discloses a tunneling method for a formation with developed cross-section confined fissure water based on pressure relief and water stoppage, comprising the following steps: Step 1, analysis of abnormal tunneling shutdown; Step 2, opening hole observation; Step 3, opening hole for water release and pressure relief; Step 4, installing a water stop hoop; Step 5, grouting and filling; Step 6, effect observation and analysis. The tunneling method of the present invention is reasonably designed, easy to operate, low in input cost, high in safety factor and good in use effect. It can effectively solve the practical problems that when the shield machine is in a formation with complex conditions and developed fissure water, it is difficult for the shield machine to tunnel, and it will cause the screw conveyor to gush, the back of the wall cannot be filled, and the tool wear is serious, etc., and the existing tunneling methods cannot ensure the smooth progress of tunneling.

Description

Technical Field

[0001] The present invention relates to the technical field of shield construction, and particularly to a tunneling method for a stratum with developed cross-section confined fissure water based on pressure relief and water stop. Background Technique

[0002] Shield construction is a fully mechanized construction method for urban rail transit construction. The main mechanical equipment used is a shield machine, which is divided into two types: earth pressure balance shield and slurry balance shield, with the earth pressure balance shield being used more frequently.

[0003] During the tunneling process of the shield machine, soil cutting and rock fragmentation are carried out through cutters. However, when encountering complex geological conditions and rich groundwater and other environmental conditions, situations such as screw conveyor gushing, inability to fill behind the lining, and severe cutter wear will occur, causing difficulties in shield construction.

[0004] In summary, with the development of rail transit construction, the diversification of engineering geological conditions and the diversification of structural cross-sections in the interval pose a severe challenge to the existing shield construction methods. This makes the existing shield tunneling methods in China unable to meet the current situation, thereby affecting the safe and smooth tunneling of the shield. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a tunneling method for a stratum with developed cross-section confined fissure water based on pressure relief and water stop in view of the above deficiencies in the prior art. It is reasonable in design, simple to operate, low in input cost, high in safety factor, and good in use effect. It can effectively solve the practical problem that when the shield machine encounters complex stratum conditions and developed fissure water stratum, the shield machine has difficulties in tunneling, and situations such as screw conveyor gushing, inability to fill behind the lining, and severe cutter wear occur, and the existing tunneling methods cannot ensure smooth tunneling.

[0006] A tunneling method for a stratum with developed cross-section confined fissure water based on pressure relief and water stop, characterized by including the following steps:

[0007] Step 1: Analysis of abnormal shutdown during tunneling: During the tunneling process in the full-section limestone section, abnormal parameters such as an increase in the soil chamber pressure and a slow tunneling speed occurred. At the same time, the water content of the slag discharged from the screw conveyor increased, and a gushing phenomenon occurred; immediately stop tunneling and analyze the reasons.

[0008] Step 2: Opening and observation: When construction parameters are abnormal and the water content of the screw increases, install a ball valve on the segment that has exited the shield tail and conduct opening and observation. It is found that there is no slurry behind the segment wall, and a large amount of clear water flows out with pressure; at the same time, it is found that the soil chamber pressure changes before and after opening the valve to release water.

[0009] Step 3. Drilling holes to drain water and relieve pressure: After determining the construction method, before tunneling, select the grouting holes above the segments 5 - 8 rings behind the shield tail, then break through the protective layer on the wall of the segment grouting holes, drain and relieve the pressure of the fissure water behind the shield tail. At the same time, use the front shield soil bin ball valve and the advanced grouting holes to drain and relieve the pressure of the confined water in the soil bin. During the water drainage process, arrange operators to observe the soil bin pressure on the shield machine control panel. When the soil bin pressure reaches the set value, notify the drainage personnel at each point to close the valves. After all personnel have withdrawn to the safe area, start tunneling;

[0010] Step 4. Installing the water stop collar: Use the grouting holes on the segments 3 - 4 rings behind the pressure relief holes to alternately inject acrylate or polyurethane to install the water stop collar. During the plugging process, constantly observe the injection pressure and the water flow in the drainage and pressure relief holes. When it is found that the injection pressure increases and the water flow in the pressure relief hole decreases, stop injecting and change to another hole to continue injecting;

[0011] Step 5. Grouting and filling:

[0012] Step 6. Effect observation and analysis: Through synchronous grouting, secondary grouting, and the combined injection of acrylate, after draining and relieving the pressure of the front shield ball valve and the shield body advanced grouting holes, the shield tunneling parameters remain stable, the screw conveyor can discharge slag normally, and the single - ring time consumption is reduced. After tunneling for 3 - 4 hours, open holes for observation at the parts where the rear grouting and filling are completed, and it is found that the holes are filled densely and there is no water flowing out.

[0013] Preferably, Step 5 further includes the following sub - steps:

[0014] (1) Before the construction of the double - liquid grout, conduct a mix - ratio test on the double - liquid grout. Select different amounts of cement and water glass for mixing, observe the setting time and strength of the grout, and find the best mix - ratio;

[0015] (2) After the water stop collar is installed, use the synchronous grouting system to first supplement the synchronous grout (thick grout) for the segments 5 - 8 rings that have exited the shield tail;

[0016] (3) When supplementing the synchronous grout, open holes for observation on the segments 6 rings behind the segments where the grout is supplemented. When slurry flows out of the observation holes, stop the synchronous grout supplement and use the double - liquid grouting system to inject the double - liquid grout of water glass + cement slurry.

[0017] The advantages and technical effects of the present invention are:

[0018] A tunneling method for a formation with cross-section confined fissure water development based on pressure relief and water stop is a brand-new cutter-changing technology for shield tunneling in domestic formations with cross-section confined fissure water development. It is beneficial to solve problems such as slow shield tunneling, screw conveyor gushing, inability to fill behind the lining, and severe cutter wear in such formations. By adopting the methods of drainage and pressure relief and multiple grouting for water stop, not only is the technical operation simple, but also the tunneling speed is increased, the tunneling efficiency is guaranteed, and the risk of opening the chamber for cutter change is reduced. The confined water is discharged through the segment grouting hole, the soil chamber ball valve, and the advanced grouting hole, so as to reduce the soil pressure at the heading face and ensure smooth tunneling. By using acrylate as a water-stop hoop and increasing the combination of simultaneous grouting and secondary grouting, the confined water is prevented from entering the heading face, and the filling of the lining wall is ensured to be dense.

[0019] A tunneling method for a formation with cross-section confined fissure water development based on pressure relief and water stop of the present invention can reduce the wear and uneven impact on the cutters, thereby increasing the service life of the cutters and reducing the risk brought by frequent cutter changes. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a flow chart of tunneling with pressure relief and water stop.

[0021] Figure 2 It is a schematic diagram of the water-stop ring and grouting filling.

[0022] Figure 3 It is a reference diagram for the drainage and pressure relief position of the advanced grouting hole.

[0023] In the figure: 1 - advanced grouting hole; 2 - screw conveyor; 3 - screw conveyor soil outlet; 4 - tail seal brush; 5 - radial grouting hole; 6 - double-fluid grout water-stop ring behind the shield tail; 7 - polyurethane water-stop ring; 8 - segment; 9 - shield body. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] To further understand the content, features, and effects of the present invention, the following embodiments are given and described in detail in conjunction with the drawings. It should be noted that this embodiment is descriptive and not restrictive, and the protection scope of the present invention cannot be limited thereby.

[0025] As Figure 1 shown, a construction method applicable to a shield tunneling formation being a full-section rock formation with relatively developed fissure water, where abnormal parameters occur during shield tunneling, the tunneling is slow, the screw conveyor gushes severely, the slurry behind the lining cannot be effectively filled, and the common shield tunneling method cannot ensure the safe and smooth tunneling of the shield. Its characteristics are that the method includes the following steps:

[0026] Step 1. Analysis of abnormal tunneling shutdown: During the tunneling process in the full-section limestone section, abnormal parameters such as an increase in the soil chamber pressure and a slow tunneling speed occurred. At the same time, the water content of the slag discharged from the screw conveyor outlet 3 of the screw conveyor 2 increased, and a gushing phenomenon occurred. Immediately stop tunneling and analyze the reasons.

[0027] In actual construction, the soil chamber pressure of the shield machine suddenly changed, the pressure increased by more than twice, the change range of the tunneling speed was relatively large, basically remaining at 2 - 8 mm / min, the water content of the soil discharged by the screw conveyor suddenly increased, a serious gushing phenomenon occurred, and the screw conveyor gate could not be opened.

[0028] Step 2. Open the hole for observation: When abnormal construction parameters occur and the water content of the screw increases, install a ball valve on the segment 8 that has exited the shield tail, and open the hole for observation. It is found that there is no slurry behind the segment wall, and a large amount of clear water flows out with pressure. At the same time, it is found that the soil chamber pressure changes before and after draining water by opening the hole.

[0029] In actual construction, when the post-grouting hole behind the shield tail is opened, no slurry is found behind the wall, a large amount of clear water gushes out with relatively high pressure and shows no sign of stopping. The soil chamber pressure inside the shield machine drops significantly, from 2.0 bar to 0.5 bar.

[0030] Step 3. Drain water and relieve pressure by opening the hole: After determining the construction method, before tunneling, select the grouting hole above the 5 - 8 rings of segments behind the shield tail, then break through the protective layer behind the segment grouting hole wall to drain and relieve the fissure water pressure behind the shield tail. At the same time, use the ball valve in the front shield soil chamber and the advanced grouting hole 1 to drain and relieve the confined water pressure in the soil chamber. During the process of draining water, arrange operators to observe the soil chamber pressure on the shield machine control panel. When the soil chamber pressure reaches the set value, start tunneling.

[0031] In actual construction, select the grouting hole at the 1 o'clock or 15 o'clock position on the top of one of the 5 - 8 rings of segments behind the shield tail as the pressure relief hole. First, install a grouting ball valve, use an electric hammer to break through the segment protective layer, start draining and relieving pressure, and at the same time open the ball valve in the front shield soil chamber and the advanced grouting hole to drain and relieve the pressure of the soil chamber. During the pressure relief process, the operator observes the soil chamber pressure on the shield machine control panel. When the soil chamber pressure reaches 0.6 bar, the operator notifies the drainage personnel at each point to close the valve through the intercom device, and starts tunneling after all personnel have withdrawn to the safe area.

[0032] In actual construction, arrange a special person to monitor the pressure relief area. At the same time, the operator must always observe the soil chamber pressure. When the soil chamber pressure drops, first determine the water flow rate with the personnel at the pressure relief parts of the soil chamber and the front shield. When the water flow rate decreases and the pressure drops to the set value, first close the pressure relief holes of the soil chamber and the front shield, observe the change of the soil pressure. When the soil pressure is relatively stable, notify the relevant personnel to withdraw to the safe position and start tunneling.

[0033] Step 4. Install the water stop collar: Use the grouting holes on the 3-4th rings of segments behind the pressure relief holes to alternately inject acrylate or polyurethane to install the water stop collar, and form an acrylate water stop ring or a polyurethane water stop ring 7. During the plugging process, constantly observe the injection pressure and the water flow in the drainage and pressure relief holes. When it is found that the injection pressure increases and the water flow in the pressure relief hole decreases, stop the injection, change the hole and continue the injection.

[0034] In actual construction, open the selected grouting hole at point 1 on the 3-4th rings of segments behind the pressure relief hole, and inject acrylate into the grouting hole through the grouting equipment. The mixing ratio of acrylate is Component A: Component B = 1:1. During the injection, constantly observe the changes in the injection pressure and the water flow in the pressure relief hole. When the injection pressure increases to 3-4 MPa and the water flow in the pressure relief hole decreases, stop the injection, open the grouting hole at point 15 of the adjacent segment and continue the injection. When the water volume is large and the acrylate effect is not good, use polyurethane for auxiliary filling.

[0035] Step 5. Grouting filling:

[0036] (1) Before the construction of the double-fluid grout, conduct a mixing ratio test on the double-fluid grout. Mix different amounts of cement and water glass, observe the setting time and strength of the grout, and find the best mixing ratio.

[0037] (2) After the installation of the water stop collar is completed, use the synchronous grouting system to first supplement the synchronous grout (thick grout) for the 5-8th rings that have exited the shield tail, and inject 10 m3 of synchronous grout.

[0038] (3) During the synchronous grout supplement, open the holes of the 6th rings of segments behind the grout replenishment pipe for observation. When slurry flows out of the observation hole, stop the synchronous grout replenishment, and use the double-fluid grouting system to inject the double-fluid grout of water glass + cement slurry, and inject 3 m3 of double-fluid grout.

[0039] In actual construction, during the synchronous grout replenishment, because the synchronous grout is thick grout and has a long setting time, 100 kg of cement is added to each cubic meter of synchronous grout to accelerate the slurry setting time. At the same time, select the mixing ratio with the shortest experimental setting time for the double-fluid grout of water glass + cement slurry, and the mixing ratio of the double-fluid grout is water glass: cement slurry = 1:1. Due to the large water content in the formation, when injecting, appropriately increase the amount of water glass according to the injection situation.

[0040] In actual construction, arrange special personnel to monitor the grouting, constantly observe the changes of the segments around the grouting holes at any time, avoid damaging the segments due to excessive grouting pressure, and at the same time observe through the pressure relief hole. If slurry appears in the pressure relief hole, immediately stop the grouting to avoid the slurry entering the cutter head.

[0041] Step 6: Effect observation and analysis: Through drainage and pressure relief, synchronous grouting, secondary grouting, and acrylate injection, the shield tunneling parameters remain stable, the screw machine can discharge slag normally, and the single-ring time consumption is reduced. After 3-4 hours of tunneling, the rear grouting filling area was opened for observation and it was found that the hole was densely filled and no water flowed out.

[0042] During the later opening and tool changing process, it was found that the tool wear and uneven impact were reduced, thereby increasing the tool life and reducing the risks brought by frequent tool changes.

[0043] In actual construction, the hoop is formed by drainage and pressure relief, synchronous grouting, secondary grouting, and acrylate filling injection. The excavation parameters are stable: thrust 1360T-1410T, torque 950kN.m-1000kN.m, cutter head speed 2.4r / min, soil pressure 0.3bar-0.6bar, excavation speed 10-18mm / min. At the same time, through the observation of the grouting holes of the pipe segment, the grouting behind the wall is dense.

[0044] In actual construction, the cutter needs to be opened and replaced after advancing 8-10 rings in the early stage, and the cutter is seriously damaged. After the pressure relief and water stopping excavation construction, the cutter needs to be opened and replaced after advancing 20-30 rings, and the cutter wear has been significantly improved, and there will be no cutter ring falling off, and the cutter will not be seriously worn. Reduce the number of openings to ensure continuous excavation.

[0045] In addition, preferably, the shield body 9 of the shield machine includes a front shield, a middle shield and a tail shield, wherein a tail shield brush 4 that is attached to the outer periphery of the pipe segment is fixedly provided on the circumferential inner wall of the tail shield; in addition, radial grouting holes 5 are opened on the middle shield; in addition, the pipe segment laid behind the shield tail is wrapped with a double-liquid slurry water-stop ring 6 behind the shield tail to realize the grouting sealing function.

[0046] In addition, compared with the prior art, the present invention also has the following advantages:

[0047] 1. The construction method of the present invention can effectively control the excavation parameters. When the excavation parameters change abnormally and the screw machine gushes seriously, an innovative process combining pressure relief and water stopping is adopted to effectively control the stability of the excavation parameters, prevent the screw machine from gushing, and thus speed up the shield excavation construction.

[0048] 2. The construction method of the present invention effectively ensures that the grouting behind the wall is fully filled and avoids the subsequent surface settlement:

[0049] The first is to control the filling of the grouting behind the wall. By using acrylic acid as a water stop ring and combining synchronous grouting with secondary grouting, the density of the grouting behind the wall of the pipe segment is effectively guaranteed.

[0050] Second, ensure the stability of ground settlement. The voids behind the segments are filled by combining multiple grouting methods to prevent the loss of fissure water in the rock stratum, effectively avoiding ground settlement or even cracking and collapse due to voids behind the segments and soil and water loss.

[0051] 3. The construction process is simple and easy to operate, effectively improving the tunneling efficiency and ensuring safety.

[0052] First, the construction process is relatively simple. The construction of this technology basically adopts common construction methods, which are simple to operate and have low requirements for the construction environment.

[0053] Second, the construction efficiency is improved. This technology effectively controls the construction parameters, avoids the gushing of the screw conveyor, reduces unnecessary downtime, increases the continuity of tunneling construction, and achieves the effect of smooth tunneling of the shield machine.

[0054] Third, reduce the risk of frequent cutter changes. The risk of cutter changes in the shield machine in water-rich strata is extremely high. By controlling the tunneling parameters, the damage and wear of the cutters are reduced, the frequency of opening the chamber for cutter changes is decreased, and the safety of personnel and equipment is guaranteed.

[0055] For the parts not described in this invention, mature products and mature technical means in the prior art are adopted.

[0056] It should be understood that those of ordinary skill in the art can make improvements or modifications according to the above description, and all such improvements and modifications shall fall within the protection scope of the appended claims of this invention.

Claims

1. A tunneling method for a stratum with developed cross-section confined fissure water based on pressure relief and water stoppage, characterized in that, it includes the following steps: Step 1, Analysis of abnormal tunneling shutdown: During the tunneling process in the full-section limestone section, abnormal parameters such as an increase in the soil bin pressure and a slow tunneling speed occurred. At the same time, the water content of the slag discharged by the screw conveyor increased, and a gushing phenomenon occurred; immediately stop tunneling and analyze the reasons. Step 2, Opening and observing: When abnormal construction parameters appear and the water content of the screw increases, install a ball valve on the segment that has exited the shield tail and conduct opening and observation. It is found that there is no grout behind the segment wall, and a large amount of clear water flows out with pressure; at the same time, it is found that the soil bin pressure changes before and after opening the valve to release water. Step 3, Opening the hole to release water and relieve pressure: After determining the construction method, before tunneling, select the grouting holes above the 5-8 rings of segments behind the shield tail, then break through the protective layer of the segment grouting hole wall to drain and relieve the fissure water behind the shield tail. At the same time, use the front shield soil bin ball valve and the advanced grouting hole to drain and relieve the confined water in the soil bin. During the water release process, arrange operators to observe the soil bin pressure on the shield machine control panel. When the soil bin pressure reaches the set value, notify the drainage personnel at each point to close the valve. After all personnel have evacuated to the safe area, start tunneling. Step 4, Constructing a water stop hoop: Alternately inject acrylate or polyurethane using the grouting holes on the 3-4 rings of segments behind the pressure relief hole to construct a water stop hoop. During the plugging process, constantly observe the injection pressure and the water flow in the drainage and pressure relief holes. When it is found that the injection pressure increases and the water flow in the pressure relief hole decreases, stop injecting and change the hole to continue injecting. Step 5, Grouting and filling: Carry out combined construction of synchronous grouting and secondary grouting. Step 6, Effect observation and analysis: Through drainage and pressure relief, synchronous grouting, secondary grouting, and combined injection of acrylate, the tunneling parameters of the shield are kept stable, the screw conveyor can discharge slag normally, and the single-ring time consumption is reduced; after tunneling for 3-4 hours, open and observe the part where the grouting and filling are completed at the back. It is found that the hole is filled densely and no water flows out.

2. A tunneling method for a stratum with developed cross-section confined fissure water based on pressure relief and water stoppage according to claim 1, characterized in that: The fifth step further includes the following sub-steps: (1) Before the construction of the double-fluid grout, conduct a mix ratio test on the double-fluid grout. Select different amounts of cement and water glass for mixing, observe the setting time and strength of the grout, and find the best mix ratio. (2) After the construction of the water stop hoop is completed, use the synchronous grouting system to first supplement the synchronous grout for the 5-8 rings that have exited the shield tail. This synchronous grout is thick grout. (3) When supplementing the synchronous grout, open and observe the 6 rings of segments behind the grout-supplemented segments. When slurry flows out of the observation hole, stop the synchronous grout supplement and use the double-fluid grouting system to inject a double-fluid grout of water glass + cement slurry.

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