阅读说明：本技术 一种联络通道顶管机施工粉砂土层中全断面渣土改良方法 (Method for improving full-section muck in silt layer in construction of connecting channel pipe jacking machine ) 是由 邓建林 李海波 赵星星 余秀平 狄鹏 郝建雷 刘阳 刘晓波 朱洪健 张永南 杨吉 于 2021-09-01 设计创作，主要内容包括：本发明涉及联络通道顶管机施工粉砂土层中全断面渣土改良方法,包括步骤：S1、渣土改良剂确定；S2、室内试验；S3、现场渣土改良剂拌制；S4、现场施工。本发明的有益效果是：本发明采用膨润土改良剂(膨润土溶液+高分子凝聚剂)进行渣土改良,高分子聚合物溶液具有较强的黏连性,能够非常好的吸纳土体水分,通过刀盘切削及螺旋机搅拌,改变渣土的渗透系数,使得渣土得到充分地改良。改良后的渣土既不容易喷涌、也不容易结泥饼,有效降低土仓内渣土的渗透性,进而遏制喷涌的发生,使盾构掘进顺畅、高效,减少停机时间,防止螺旋机中渣土固结,从而保障施工的安全顺利。(The invention relates to a method for improving full-section muck in a silt layer during the construction of a connecting channel push bench, which comprises the following steps: s1, determining a muck modifier; s2, performing indoor test; s3, mixing the on-site muck modifier; and S4, performing site construction. The invention has the beneficial effects that: according to the invention, the bentonite modifier (bentonite solution and high-molecular coagulant) is adopted for modifying the residue soil, the high-molecular polymer solution has strong adhesion, can well absorb the water in the soil body, and the permeability coefficient of the residue soil is changed by cutting with a cutter and stirring with a screw machine, so that the residue soil is fully modified. The improved muck is not easy to gush and cake, the permeability of the muck in the soil bin is effectively reduced, and the gush is restrained, so that the shield tunneling is smooth and efficient, the downtime is reduced, the solidification of the muck in the screw machine is prevented, and the safety and smoothness of construction are guaranteed.)

1. A method for improving full-section muck in a silt layer during construction of a connecting channel push bench is characterized by comprising the following steps:

s1 determination of muck modifier

S1.1, in a connecting channel pipe jacking method construction preparation stage, judging the soil property and the permeability of a pipe jacking machine in a tunneling range by using a geological survey report in an originating tunnel portal ring beam range, and selecting the type and the proportion of a muck modifier;

s1.2, adopting a bentonite modifier aiming at the water-rich silt layer, wherein the bentonite modifier mainly comprises a bentonite solution and a high-molecular coagulant;

s2, laboratory test

S2.1, sampling in site construction before tunneling, and testing the water-containing state of the rock soil of the excavation face;

s2.2, preparing a proper test soil sample, formulating test schemes according to different mixing amounts by adopting bentonite modifiers with different proportions, carrying out slump tests of the improved muck, carrying out a plurality of groups of parallel tests on each test scheme, taking an average value as a final result, and enabling the slump to be within the range of 150-200mm, namely meeting the requirement of the muck plastic flow state;

s2.3, according to the slump test result, carrying out a stirring test according to the proportioning scheme in the step S2.2, putting the uniformly stirred soil sample into a stirring barrel, opening an instrument, continuously stirring for 1-2 min after the stirring current is stable, stopping stirring, taking the current in a stable section to calculate the torque, and taking the proportion with relatively small torque and small fluctuation of the stirring torque along with the change of time as the final proportion;

s3, mixing the on-site muck modifier

S3.1, preparing a bentonite stirring barrel and a slurry storage tank on one side of the connecting channel pipe jacking machine trolley, and stirring 5m according to the final proportioning requirement of an indoor test before tunneling³-10m³The bentonite solution is stored in the slurry storage tank;

s3.2, after the bentonite solution is stirred, fully dissolving the weighed polymer flocculant with water, introducing the polymer flocculant into a bentonite solution slurry storage tank, and fully and uniformly stirring;

s4, field construction

S4.1, in the tunneling process, according to the slag discharging effect, injecting a bentonite improving agent into the pipe jacking machine through a grouting pipeline and mixing with excavated soil through a cutter head, a soil bin and a screw machine injection hole, and improving the whole section of the excavated soil to enable the excavated soil to be in a plastic flowing state;

and S4.2, acquiring various construction operation parameters through a data real-time acquisition system in the pipe jacking machine in the tunneling process, and judging the muck improvement effect.

2. The improvement method of the full-section muck in the silt layer of the communication channel pipe jacking machine construction, which is characterized by comprising the following steps of: in step S1.2, in the water-rich silt layer, the proportion of the bentonite solution in the bentonite modifier to the polymer flocculant is (1300:1) - (1500: 1).

3. The improvement method of the full-section muck in the silt layer of the communication channel pipe jacking machine construction, which is characterized by comprising the following steps of: the proportion of the bentonite to the water in the bentonite solution is (1:5) - (1: 3).

4. The improvement method of the full-section muck in the silt layer of the communication channel pipe jacking machine construction, which is characterized by comprising the following steps of: in the step S1.2, the doping volume ratio of the bentonite modifier to the slag soil in the water-rich silt layer is 15-20%.

5. The improvement method of the full-section muck in the silt layer of the communication channel pipe jacking machine construction, which is characterized by comprising the following steps of: in the step S1.2, the bentonite in the bentonite solution is sodium bentonite, the pH value of the sodium bentonite is 7.5-10, and the viscosity is 2-10 Pa.s.

6. The improvement method of the full-section muck in the silt layer of the communication channel pipe jacking machine construction, which is characterized by comprising the following steps of: in step S1.2, the polymeric flocculant is a solid particle.

7. The improvement method of the full-section muck in the silt layer of the communication channel pipe jacking machine construction, which is characterized by comprising the following steps of: in the step S3.1, the bentonite solution is kept stand and bulked for more than 12 hours after being prepared in a bentonite stirring barrel.

8. The improvement method of the full-section muck in the silt layer of the communication channel pipe jacking machine construction, which is characterized by comprising the following steps of: in step S3.2, the polymer flocculant and the bentonite solution are stirred uniformly and then are kept stand and expanded for more than 12 hours.

9. The improvement method of the full-section muck in the silt layer of the communication channel pipe jacking machine construction, which is characterized by comprising the following steps of: in step S4.1, the screw machine is provided with a plurality of residue soil improvement injection ports, and a foam and bentonite injection system is connected.

10. The improvement method of the full-section muck in the silt layer of the communication channel pipe jacking machine construction, which is characterized by comprising the following steps of: in step S4.1, the grouting pipeline includes a grouting pipe, a pumping device control line, a control gate, a pressure gauge, and a pumping device power control device and an injection device.

Technical Field

The invention relates to the technical field of subway communication channel construction, in particular to a method for improving full-section muck in a silt layer in communication channel pipe jacking machine construction.

Background

An interconnection channel is required to be arranged between the urban rail transit uplink and downlink tunnel, the main function of the interconnection channel is to communicate the subway uplink and downlink tunnel, people can be evacuated in emergency, the interconnection channel can also be used as a life channel for emergency rescue, and water collection and drainage of the tunnel are considered. For a long time, tunnel construction technologies such as mining method excavation and the like are mostly adopted for urban rail communication channels, grouting or freezing reinforcement is assisted to ensure stability of surrounding rocks during tunnel excavation, but the construction method has natural defects in the aspects of reinforcement construction or excavation construction and the like, and the conventional freezing method has the problems of long construction period, high construction cost, hidden quality troubles and the like. In recent years, a series of applications in various major cities in China have been developed by adopting a mechanical method (a shield method and a pipe jacking method) to excavate a communication channel. During the construction of connecting passage between shield and pipe-jacking method, earth pressure balance shield and pipe-jacking machine are used, and the principle is that the dregs in soil bin are used as medium for stabilizing excavation face, a soil bin is formed between cutter head and cutter head back partition board, the cutter head rotates, the excavated dregs enter the soil bin, and the dregs are output by the spiral soil discharger on the cutter head back partition board. The soil pressure in the soil bin is determined by the rotary excavation speed of the cutter head and the soil discharging speed of the spiral soil discharging device.

A mechanical method (a shield method and a pipe jacking method) for excavating a communication channel is a technology of 'punching in a hole', the existing tunnel is drilled by adopting a direct cutting method to complete the excavation of the other tunnel, the problems of leakage water and formation stability under various geological conditions of a deeply buried formation are necessarily solved, the starting and receiving are totally closed by adopting a conversion technology of a half-sleeve tail sealing brush and a shield tail sealing brush, the tunneling is always in a totally closed state, and the tunnel is narrow in operation space, equipment integration and performance change. When the earth pressure balance shield machine and the pipe jacking machine penetrate through a water-rich silt stratum with high permeability, the water permeability of the slag in the soil bin is high, the workability is poor, the water pressure is high, the water pressure can break through the slag in the spiral soil outlet device to form a gushing, namely, the high-pressure water flow carries the slag to gush out. Large-scale gushing is likely to cause instability of the tunnel structure, resulting in significant casualties and property loss.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provide a method for improving the full-section muck in the silt layer in the construction of the pipe jacking machine of the connecting channel.

The method for improving the full-section muck in the silt layer in the construction of the connecting channel push bench comprises the following steps:

s1 determination of muck modifier

S1.1, in a connecting channel pipe jacking method construction preparation stage, judging the soil property and the permeability of a pipe jacking machine in a tunneling range by using a geological survey report in an originating tunnel portal ring beam range, and selecting the type and the proportion of a muck modifier;

s1.2, adopting a bentonite modifier aiming at the water-rich silt layer, wherein the bentonite modifier mainly comprises a bentonite solution and a high-molecular coagulant;

s2, laboratory test

S2.1, sampling in site construction before tunneling, and testing the water-containing state of the rock soil of the excavation face;

s2.2, preparing a proper test soil sample, formulating test schemes according to different mixing amounts by adopting bentonite modifiers with different proportions, carrying out slump tests of the improved muck, carrying out a plurality of groups of parallel tests on each test scheme, taking an average value as a final result, and enabling the slump to be within the range of 150-200mm, namely meeting the requirement of the muck plastic flow state;

s2.3, according to the slump test result, carrying out a stirring test according to the proportioning scheme in the step S2.2, putting the uniformly stirred soil sample into a stirring barrel, opening an instrument, continuously stirring for 1-2 min after the stirring current is stable, stopping stirring, taking the current in a stable section to calculate the torque, and taking the proportion with relatively small torque and small fluctuation of the stirring torque along with the change of time as the final proportion;

s3, mixing the on-site muck modifier

S3.1, preparing a bentonite stirring barrel and a slurry storage tank on one side of the connecting channel pipe jacking machine trolley, and stirring 5m according to the final proportioning requirement of an indoor test before tunneling³-10m³Swelling and swellingThe soil solution is stored in the slurry storage tank;

s3.2, after the bentonite solution is stirred, fully dissolving the weighed polymer flocculant with water, introducing the polymer flocculant into a bentonite solution slurry storage tank, and fully and uniformly stirring;

s4, field construction

S4.1, in the tunneling process, according to the slag discharging effect, injecting a bentonite improving agent into the pipe jacking machine through a grouting pipeline and mixing with excavated soil through a cutter head, a soil bin and a screw machine injection hole, and improving the whole section of the excavated soil to enable the excavated soil to be in a plastic flowing state;

and S4.2, acquiring various construction operation parameters through a data real-time acquisition system in the pipe jacking machine in the tunneling process, and judging the muck improvement effect.

Preferably, the method comprises the following steps: in step S1.2, in the water-rich silt layer, the proportion of the bentonite solution in the bentonite modifier to the polymer flocculant is (1300:1) - (1500: 1).

Preferably, the method comprises the following steps: the proportion of the bentonite to the water in the bentonite solution is (1:5) - (1: 3).

Preferably, the method comprises the following steps: in the step S1.2, the doping volume ratio of the bentonite modifier to the slag soil in the water-rich silt layer is 15-20%.

Preferably, the method comprises the following steps: in the step S1.2, the bentonite in the bentonite solution is sodium bentonite, the pH value of the sodium bentonite is 7.5-10, and the viscosity is 2-10 Pa.s.

Preferably, the method comprises the following steps: in step S1.2, the polymeric flocculant is a solid particle.

Preferably, the method comprises the following steps: in the step S3.1, the bentonite solution is kept stand and bulked for more than 12 hours after being prepared in a bentonite stirring barrel.

Preferably, the method comprises the following steps: in step S3.2, the polymer flocculant and the bentonite solution are stirred uniformly and then are kept stand and expanded for more than 12 hours.

Preferably, the method comprises the following steps: in step S4.1, the screw machine is provided with a plurality of residue soil improvement injection ports, and a foam and bentonite injection system is connected.

Preferably, the method comprises the following steps: in step S4.1, the grouting pipeline includes a grouting pipe, a pumping device control line, a control gate, a pressure gauge, and a pumping device power control device and an injection device.

The invention has the beneficial effects that:

1. the invention provides a method for improving full-section muck in a silt layer during pipe jacking machine construction of an articulated tunnel. According to the invention, the bentonite modifier (bentonite solution and high-molecular coagulant) is adopted for modifying the residue soil, the high-molecular polymer solution has strong adhesion, can well absorb the water in the soil body, and the permeability coefficient of the residue soil is changed by cutting with a cutter and stirring with a screw machine, so that the residue soil is fully modified. The improved muck is not easy to gush and cake, the permeability of the muck in the soil bin is effectively reduced, and the gush is restrained, so that the shield tunneling is smooth and efficient, the downtime is reduced, the solidification of the muck in the screw machine is prevented, and the safety and smoothness of construction are guaranteed.

2. The muck modifier is simple to prepare, and special equipment does not need to be purchased; the chemical properties of the bentonite solution and the high-molecular coagulant are stable, the modifier is easy to store and implement, the influence on the engineering progress is small, the stratum adaptability of the earth pressure balance shield machine and the pipe jacking machine connection channel construction is improved, and the subway construction cost is also reduced.

3. The slag soil improvement slurry preparation and field implementation mode is reasonable and efficient, the problems of pipe blockage, failure and the like of the slurry can be effectively avoided, and the improvement efficiency is improved.

Drawings

FIG. 1 is a flow chart of a full-section muck improvement method in a silt layer in the contact channel pipe jacking machine construction of the invention.

Detailed Description

The present invention will be further described with reference to the following examples. The following examples are set forth merely to aid in the understanding of the invention. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.

In addition, for the water-rich silt stratum, the muck is required to be improved, additives such as water, foam, bentonite, high molecular polymer and the like are injected into a cutter disc surface, a soil cabin or a spiral conveyer through a special device configured by a shield, and the additives are mixed with the muck by utilizing the rotary stirring of the cutter disc and the rotary stirring of the soil cabin stirring device or the spiral conveyer, so that the muck cut by the shield has better flowing plasticity, proper consistency, lower water permeability and lower frictional resistance, and the gushing phenomenon of the earth pressure balance shield machine and the pipe jacking machine in the water-rich stratum can be effectively improved. The invention provides a method for improving full-section muck in a silt layer during construction of a connecting channel pipe jacking machine, which is characterized in that bentonite solution and a high-molecular coagulant are adopted for improving the muck, the high-molecular polymer solution has strong adhesion and can well absorb water in a soil body, the permeability coefficient of the muck is completely changed through cutter head cutting and spiral machine stirring, so that the muck is fully improved, the improved muck is not easy to gush and cake, the permeability of the muck in a soil bin is effectively reduced, the occurrence of gush is restrained, shield tunneling is smooth and efficient, the downtime is reduced, and the muck in a spiral machine is prevented from being solidified, thereby ensuring the safety and smoothness of construction.

Example one

The embodiment of the application provides a method for improving full-section muck in a silt layer during construction of a push bench of an interconnecting channel, which comprises the following steps:

1. determination of muck modifier

1) In the preparation stage of the pipe jacking method construction of the communication channel, in the range of an originating portal ring beam, the soil property and the permeability of the pipe jacking machine in the tunneling range are judged by utilizing a geological survey report, and the type and the proportion of a muck modifier are selected.

2) And a bentonite modifier (bentonite solution and a high-molecular coagulant) is adopted for the water-rich silt layer so as to reduce the permeability coefficient of the water-rich stratum. In the water-rich silt layer, the proportion of the bentonite solution in the bentonite modifier to the polymer flocculant is controlled according to 1400: 1. Expansion deviceThe proportion of bentonite and water in the bentonite solution in the soil moistening improver is 1:4, and the injection speed of the equipment into the bentonite, namely the injection rate, is 25-40% according to the propulsion speed in the propulsion process. The doping volume ratio of the bentonite modifier to the slag soil is 15-20%. The bentonite in the bentonite solution is sodium bentonite, the pH value of the sodium bentonite is 7.5-10, and the viscosity is 2-10 Pa.s. The polymer flocculant is solid particles, and is AP104 type. After the muck modifier is added, the permeability coefficient of the silt is from 1.0 multiplied by 10^-4～1×10^-3The cm/s is reduced to 1.0 multiplied by 10^-5～1×10^-4cm/s to meet the requirement of preventing gushing.

2. Laboratory test

1) Before tunneling, sampling is carried out in site construction, and the water content state of the rock soil of the excavation face is tested.

2) Preparing a proper test soil sample according to the slump test requirement, formulating test schemes by adopting bentonite modifiers (bentonite solution and high-molecular coagulant) with different proportions according to different mixing amounts, carrying out the slump test of the improved muck, carrying out three groups of parallel tests on each test scheme, taking an average value as a final result, and considering that the slump of the sandy soil is within the range of 150-200mm, namely meeting the requirement of the plastic flow state of the muck.

3) According to the slump test result, carrying out a stirring test according to the proportioning scheme in the step 2), putting the uniformly stirred soil sample into a stirring barrel, opening an instrument, continuously stirring for 1min after the stirring current is stable, taking the current of the stable section to calculate the torque, and taking the proportion of the bentonite modifier which has relatively small torque and small fluctuation of the stirring torque along with the change of time as the final proportion.

3. On-site muck modifier mixing

1) A special bentonite stirring barrel and a slurry storage tank are arranged on the right side of a 4# trolley of the connecting channel pipe jacking machine, and before tunneling, 5m of bentonite is stirred according to the final proportioning requirement of an indoor test³And the bentonite solution is stored in a slurry storage tank. After the bentonite solution is prepared in the bentonite stirring barrel, the bentonite solution needs to be kept stand and puffed for more than 12 hours so as to ensure that indexes such as consistency, viscosity and the like of the bentonite solution meet construction requirements.

2) After the bentonite solution is stirred, the weighed polymer flocculant is fully dissolved by water, and is introduced into a bentonite solution slurry storage tank to be fully and uniformly stirred. The polymer coagulant and the bentonite solution are uniformly stirred and then still stand for expansion for more than 12 hours to ensure that indexes such as the consistency, the viscosity and the like of the bentonite solution meet the construction requirements.

4. On-site construction

1) In the tunneling process, according to the slag discharging effect, the bentonite modifier is injected into the pipe jacking machine through the cutter head, the soil bin and the injection hole of the screw machine and mixed with the excavated soil through the grouting pipeline, and the whole section of the excavated soil is modified to enable the excavated soil to be in a plastic flowing state. The maximum passing grain diameter of the screw machine is phi 230 multiplied by 140mm, and the maximum slag discharging capacity is 20m³The driving power is 55kW, the maximum torque is 40kN.m, and the screw machine is provided with three slag improvement injection ports and can be connected with a foam and bentonite injection system. The grouting pipeline comprises a grouting pipe, a pumping device control line, a control gate, a pressure gauge, a pumping device power control device and an injection device.

2) And in the tunneling process, various construction operation parameters such as the torque of the screw machine and the soil pressure change condition in the soil cabin are acquired through a data real-time acquisition system in the pipe jacking machine, and the muck improvement effect is judged. After the muck modifier is added, the slump of the muck is increased from 10cm-15cm to 15cm-20 cm.

Example two

1. Overview of the engineering

The left line length of the Hangzhou inter-sea-city railway shield interval from the Yuhang high-speed railway station to the allowable villages and towns station (called Yu-allowable shield interval for short) is 3126.22m, and the starting mileage is as follows: ZDK0+437.570, end point mileage: ZDK3+563.487, long chain 0.303 m; the left-allowable shield interval right line length is 3126.555m, and the starting point mileage is as follows: YDK0+437.570, end point mileage: YDK3+563.847, long chain 0.278 m. The minimum curve radius of the line is 800m, the maximum curve radius is 4000m, the tunnel buried depth is 7.6-25 m, the line spacing is 10.8-16 m, and the maximum longitudinal slope is 28 per mill. The shield interval contains 1 middle air shaft, 5 contact passageways: wherein 1 and middle air shaft build jointly, 1 and pump house build jointly, wherein 3 connecting channels adopt the push pipe method to construct.

In the interval, 3 mechanical method communication channels are arranged on a left DK0+762.798 (right DK0+760.000), a right DK1+237.420 (left DK1+239.019) and a right DK1+800.000 (left DK1+ 801.599). The mileage of the 1# connection channel center is left DK0+762.798 (right DK0+760.000), the track surface of the main tunnel is-22.647 (-22.689), the center elevation of the connection channel tunnel is-20.597 (-20.639), the thickness of the lining top covering soil is about 24.1m, and the line spacing is 13.0 m; the mileage of the 2# connection channel center is right DK1+237.420 (left DK1+239.019), the track surface of the main tunnel is-25.464 (-25.463), the center elevation of the connection channel tunnel is-23.414 (-23.414), the thickness of the lining top covering soil is about 26.65m, and the line spacing is 13.0 m; the mileage of the 3# communication channel center is right DK1+800.000 (left DK1+801.599), the track surface of the main tunnel is-21.861 (-21.850), the center elevation of the communication channel tunnel is-19.811 (-19.800), the thickness of the lining top covering soil is about 19.96m, and the line spacing is 13.0 m.

According to the upper surface stratum, the 3# and 2# communication channels are the same, and the 1# communication channel stratum is mainly a silt stratum. The modifier is used in the stratum with the silt and the clay of 7-2-1 silt, and mainly aims to prevent mud cakes from being formed on a cutter head and increase the flowability of dregs. The main consideration of the slag soil fluidity and the water and soil loss in the main silt stratum is that bentonite and a high-molecular coagulant are adopted to ensure the soil pressure balance and the wall protection effect. The main solution measures are as follows: when the screw machine is difficult to feed soil, the soil pressure set value of the excavation surface is increased, the propelling speed is increased, and the screw machine can feed soil normally; the precision is ensured when the screw machine is installed, and the lubrication of the bearing is enhanced in the running process; controlling the penetration degree when the concrete segment is ground, injecting a lubricating medium, improving the fluidity of the slag, ensuring the concrete segment and the glass fiber ribs to be fully cut and smoothly discharged; when the screw machine is stuck, cleaning the blocked part in time; (risk) sufficiently improving the residue soil to ensure that the residue soil has good water tightness and viscosity; the downtime is reduced, and the solidification of the residue soil in the screw machine is prevented.

2. Improvement scheme of muck

The purpose of improving the dregs is as follows: and soil body modifying agents are injected into the excavation surface to achieve the lubricating effect, so that the abrasion of the cutter is reduced, the soil quality is modified, the construction problems such as cake formation and the like are prevented, and the shield tunneling is smooth and efficient.

Soil body improvement requirements: (1) soil in front of the cutter head needs to be improved in advance and continuously; (2) the soil body cut by the cutter head is improved to have good fluidity, the pressure balance between the soil body in the soil bin and the soil body outside the cutter head can be established in time, and the stability of the soil body above the shield cut in the shield tunneling process is maintained; (3) the fluidity of the soil body is increased, the soil body cut by the cutter head and entering the soil bin can be discharged in time, the formation of mud cakes in the bin is reduced, and the skeleton arch effect of particles can not be formed;

TABLE 1 muck-improving materials and effects

According to different stratums, different material types are selected for improving the slag, and the slag is effectively prevented from gushing and the fluidity of the slag is promoted in the water-rich silt layer; the bentonite solution and the polymer flocculant (if the water content of the stratum is larger, the polymer flocculant is adopted to improve the consistency of the bentonite solution) are preferably selected for improving the slag.

TABLE 2 muck modifier ratio

TABLE 3 injection of muck improver

Item	Injection rate	Incorporation by volume ratio
			Parameter(s)	30％	16％

According to the proportion, a special bentonite stirring barrel and a special bentonite slurry storage tank are arranged on the right side of the 4# trolley, and 5-square bentonite solution is prepared for standby by constructors according to the proportion requirement before tunneling. In the tunneling process, a pipe jacking machine driver properly adjusts the injection amount of bentonite to improve the slag soil through a cutter head, a soil bin and a screw machine injection hole according to the slag discharging effect.

3. Improvement effect of residual soil

According to the actual moment of torsion of mechanical method contact passageway contrast table 4 can see out, 1# on the whole, 3# contact passageway soil storehouse pressure is comparatively stable, soil storehouse pressure oscillation is frequent in 2# contact passageway work progress, it is extremely unstable, cause certain settlement influence to the earth's surface, receive stage 2#, 3# contact passageway is tunneled in the pressure release basically, and this kind of tunneling mode makes the inside filler of sleeve can only discharge through the extruded mode, unable all normal discharge, the slip casting in-process, because of anterior pressure is not enough, the thick liquid flows back to soil storehouse internal consolidation, increase certain construction risk.

Soil pressure comparison table for propulsion parameters of communication channels of 41 #, 2#, and 3#, respectively

Ring number	1# communication channel	2# communication channel	3# communication channel
				1	1.78bar	0.29bar	1.5bar
2	1.80bar	1.55bar	1.8bar
				3	1.99bar	1.56bar	1.9bar
4	2.15bar	0.75bar	1.8bar
				5	2.17bar	1.15bar	1.7bar
6	1.95bar	1.05bar	1.8bar
				7	2.25bar	0.00bar	1.7bar
8	2.15bar	0.33bar	0.3bar
				9	2.00bar	0.00bar	0.4bar

According to the actual torque comparison table 5 of the mechanical method communication channel, the actual thrust and torque variation trends during the pipe jacking construction period are basically the same. The average torque of the 1# communication channel is about 240KN.m, the average torque of the 2# communication channel is about 320KN.m, and the average torque of the 3# communication channel is about 380KN.m, so that the change is stable.

TABLE 51 #, 2#, 3# interconnection channel propulsion parameter torque comparison table

Ring number	1# communication channel	2# communication channel	3# communication channel
				1	144KN·m	300KN·m	300KN·m
2	117KN·m	500KN·m	700KN·m
				3	200KN·m	300KN·m	180KN·m
4	248KN·m	260KN·m	260KN·m
				5	263KN·m	300KN·m	300KN·m
6	250KN·m	300KN·m	280KN·m
				7	200KN·m	300KN·m	200KN·m
8	300KN·m	100KN·m	400KN·m
				9	150KN·m	300KN·m	100KN·m

In conclusion, the improved slag soil of the project has no gushing and no mud cake, effectively reduces the permeability of the slag soil in the soil bin, further restrains the occurrence of gushing, ensures that the shield tunneling is smooth and efficient, reduces the downtime, prevents the slag soil in the screw machine from being solidified, and ensures the safety and smoothness of construction.