Disclosure of Invention
The invention aims to solve the technical problem of providing a construction method for the shield of the ultra-shallow buried tunnel to penetrate through the existing pipeline, which is convenient to construct and high in safety.
In order to solve the problems, the technical scheme adopted by the invention is as follows: a construction method for enabling an ultra-shallow tunnel shield to penetrate through an existing pipeline downwards comprises the following steps:
a construction method for constructing an ultra-shallow tunnel shield through an existing pipeline is carried out according to shield tunnel construction and acceptance criteria (GB50446-2008), pre-penetration pipeline construction test grouting parameters and construction tunneling parameters, and specifically comprises the following steps:
step 1) reinforcing the ground surface of an existing pipeline;
step 2), laying monitoring point positions;
step 3) carrying out a pre-penetration pipeline construction test;
wherein, the pre-penetration pipeline construction test is carried out in two steps,
firstly, presetting grouting parameters and initial values of tunneling parameters, wherein the preset grouting parameters and the initial values of the tunneling parameters are grouting parameters and tunneling parameters of tunneling construction before a test section of an existing pipeline is penetrated;
then, selecting a test section with a distance of 3-5 rings (such as 73-75 rings) out of the front 20 rings of the pipeline position to perform a pre-penetration pipeline construction test, and adjusting grouting parameters and tunneling parameters to obtain grouting parameters and tunneling parameters which meet shield-method tunnel construction and acceptance specifications;
if the obtained grouting parameters and the obtained tunneling parameters do not meet the shield tunnel construction and acceptance criteria, adjusting the grouting parameters and the tunneling parameters to carry out pre-penetration pipeline construction again until the shield tunnel construction and acceptance criteria are met;
secondly, performing a pre-penetration pipeline construction test at a distance of 3-5 rings (such as 76-78) after the test section in the first step, and verifying and modifying parameters obtained in the first step according to shield tunnel construction and acceptance specifications;
grouting before each propulsion test, acquiring data of each monitoring point position, obtaining an initial value, measuring after 1/4 to 1/2 of the length of the first propulsion segment, analyzing the size rule of settlement and timely modifying tunneling parameters according to urban rail transit measurement standards (GB50308-2008), performing tunneling construction for 1/4 to 1/2 of the length of the second segment, acquiring data after construction, mastering the settlement and modifying the tunneling parameters, performing tunneling construction for 1/4 to 1/2 of the length of the third segment, and so on until the test segment is finished;
and 4) performing under-penetrating construction on the existing pipeline according to the grouting parameters and the tunneling parameters obtained in the step 3), and monitoring each monitoring point position in the construction process.
Further, the step 1) specifically comprises: firstly, adopting cement-water glass double-liquid slurry to carry out grouting reinforcement on an existing pipeline area, wherein the distance between grouting holes is 2.5 multiplied by 2.5m, and grouting from the upper boundary of a non-permeable layer to the top of a sand layer; the reinforcing range is 12m-15m longitudinally relative to the central line of the water pipe in the tunnel body range, and the reinforcing range is 3m-5m from the right upper side and two sides of the tunnel to the outer side of the outer side line of the structure;
and then, after grouting reinforcement is completed, reserving sleeve valve pipes on a row of grouting holes which are respectively positioned at two sides of the existing pipeline and close to the existing pipeline.
Grouting hole position arrangement principle:
according to the calculation that the grouting diffusion radius is 2.3m, consideration is given to the fact that grouting reinforcement needs to be occluded, so that R is 1.5m, namely the distance between grouting holes is 3m, the tunnel excavation diameter is 8.8m, the influence range of shield construction is considered, so that 5 holes are arranged in each cross section, the grouting pressure is possibly large in consideration of the previous ground uplift condition, and therefore pressure relief holes are arranged between the grouting holes and 1.5m away from the grouting holes.
Further, the step 2) is specifically as follows: the settlement monitoring point location is arranged according to the following steps: five points are distributed on one cross section, one point is arranged at the position of a middle arch crown, two points are symmetrically distributed on two sides, one of the point positions on the two sides is arranged in a tunnel limit, and the other point position on the two sides is arranged outside the tunnel limit.
Further, the construction method of the settlement monitoring point location comprises the following steps:
drilling holes by a geological drilling machine to distribute monitoring holes; the aperture is 108 mm;
firstly, drilling to a designed depth; the rig is then removed; secondly, putting a phi 50mm PVC pipe into the hole; thirdly, sand is backfilled between the PVC pipe and the hole wall to fix the PVC pipe, and the backfilling depth is 1/2-2/3 of the designed depth; then, a reinforcing steel bar with the diameter of 18mm is placed in the PVC pipe to be used as a monitoring point, and finally, an initial value is obtained after the monitoring is finished.
Further, the step 3) is specifically as follows:
step I, performing first-time trial grouting;
firstly, determining grouting hole arrangement and grouting parameters;
two rows of slurry are injected for the first test injection, and each row has at least 5 or 7 points; the distance is 3m-5 m;
then, monitoring the settlement of the test grouting process, and distributing monitoring points on two cross sections to obtain an initial value;
the distribution range is that the distance in front of the cutter head position of the existing shield tunneling machine is not less than 10 m; 3 points are arranged on each cross section, and deep monitoring points are distributed between 0.5m and 1m below the bottom of the water pipe at the central point of the pipe piece; laying shallow monitoring points 0.2-0.5 m above the top of the water pipe at the central point between the pipe pieces, wherein the monitoring frequency is 3 times/day;
finally, analyzing the ground surface monitoring data of the test grouting test section according to urban rail transit measuring specification (GB50308-2008), thereby obtaining grouting parameters meeting shield tunnel construction and acceptance specification (GB 50446-2008);
step II, performing second test grouting;
and (4) repeating the content of cross section construction in the step I on the third cross section, and verifying and modifying the parameters obtained by the first trial grouting in the previous step I.
Further, the step 4) specifically comprises:
firstly, propelling the shield tunneling machine at a constant speed according to tunneling parameters determined by a test section, controlling the soil output, ensuring sufficient synchronous grouting amount, and arranging assembling hand-assembled duct pieces to pass through the existing pipeline area;
then, injecting and adding foam or bentonite according to the stratum condition in the construction; and should be monitored in due course.
Further, before reinforcing the surface of the existing pipeline, the following steps should be carried out:
I) performing risk assessment and designing a scheme;
II) maintaining and repairing the shield machine according to a maintenance manual; the shield machine is inspected and maintained in advance, all systems of the shield machine are overhauled comprehensively, the shield machine is guaranteed to be in a good running state, the shield machine is prevented from being shut down or opening a warehouse to inspect machines and tools due to mechanical faults, and additional settlement is reduced;
and III) combining the working parameters of the shield machine in the step b and the data in the step a to design initial parameters.
Adopt the produced beneficial effect of above-mentioned technical scheme to lie in:
in order to ensure that the water pipe is intact, a pre-penetration construction test is carried out, a soil body is reinforced by adopting a chemical modifying agent, and the disturbance of the upper soil body is monitored by monitoring and timely modifying grouting parameters and tunneling parameters in real time in the test process, so that more reasonable construction parameters are obtained. The construction proves that the parameters obtained after the pre-penetrating pipeline construction test are reasonable, the ground settlement can be effectively controlled, the construction of the downward-penetrating Australian water supply pipe tunnel is safely and smoothly completed, and reference are provided for the construction of other shield projects for downward penetrating the existing pipeline in the coastal soft soil layer.
Examples
The construction method is characterized in that a construction test for pre-penetration is firstly carried out, settlement real-time monitoring is carried out, optimal grouting parameters and tunneling parameters are determined, then the construction of the under-penetration Australian water pipe shield is carried out according to the parameters, and a set of ultra-shallow shield tunnel under-penetration existing pipeline construction deformation control technology is summarized in the whole process.
A newly-built Zhuhai urban area to the Zhuhai airport intercity rail transit project tunnel penetrates through the Australian water supply pipe from the north to the horizontal organ section, the tunnel surrounding rock is a soft soil layer, the Australian water supply pipe on the tunnel belongs to the lifeline project, the distance is short (4.8m), the strength is low, and the settlement control requirement is high. In order to ensure that the water pipe is intact, a pre-penetration construction test is carried out, a soil body is reinforced by adopting a chemical modifying agent, and the disturbance of the upper soil body is monitored by monitoring and timely modifying grouting parameters and tunneling parameters in real time in the test process, so that more reasonable construction parameters are obtained. The construction proves that the parameters obtained after the pre-penetrating pipeline construction test are reasonable, the ground settlement can be effectively controlled, the construction of the downward-penetrating Australian water supply pipe tunnel is safely and smoothly completed, and reference are provided for the construction of other shield projects for downward penetrating the existing pipeline in the coastal soft soil layer.
the method comprises the following steps of according to settlement control standards, referring to shield tunnel construction and acceptance criteria (GB50446-2008), referring to urban rail transit measurement criteria (GB50308-2008) according to analysis settlement size rules, and 3, referring to reasonable grouting parameters and tunneling parameters, wherein the reasonable grouting parameters and tunneling parameters refer to construction parameters of shield tunnel construction and acceptance criteria, which enable settlement deformation to be smaller and disturbance to peripheral soil bodies to be smaller, specifically are construction parameters with settlement control within 7mm, wherein the concrete parameters are that the grouting parameters comprise grouting pressure of 0.18-1.2 MPa, grout (liquid A) water-cement ratio of 1:1, water glass (liquid B) proportion (water glass: water cutterhead of 1: 8-1: 9, liquid A: liquid B of 1:1, cement amount (package/m) of 5.5-6, driving parameters of 2200-2300, propelling speed of 0-12 mm/min, torque of 1.3: 1.6m, MNpressure of 0.7: 0.75-0 bar, and soil driving speed of KN of 0-75 rpm.
The method specifically comprises the following steps:
step a: performing risk assessment and designing a scheme;
in order to ensure that the shield machine can safely and smoothly pass through the water supply pipe, refer to the shield method tunnel construction and acceptance standard (GB 50446-2008); engineering geological supplement reconnaissance report between imported transom tunnel and Bay boy north; urban rail transit survey regulations (GB 50308-2008); concrete and reinforced concrete drains (GB/T11836-1999); combining a horizontal and vertical cross-sectional diagram of a section from a No. 1 working well to a gulf baby north station to a gulf baby station; changing a tunnel stratum reinforcement design drawing in an entrance section-bay sub north station section into a newly-built engineering cross organ tunnel construction drawing in an intercity arch north to cross organ section from the Zhuhai city area to the Zhuhai airport; providing relevant data for Australian companies by the Zhuhai Water services group; the construction team performs grouting construction experience and research results in tunnel sections of the tunnels of Guangzhou, Shenzhen, Dongguan and the like, and the construction management level, the technical level, the scientific research level and the mechanical equipment matching capacity of the construction team.
Step b: maintaining and repairing the shield machine according to a maintenance manual;
the shield machine is inspected and maintained in advance, all systems of the shield machine are overhauled comprehensively, the shield machine is guaranteed to be in a good running state, the shield machine is prevented from being shut down or opening a warehouse to inspect machines and tools due to mechanical faults, and additional settlement is reduced;
step c: b, combining the working parameters of the shield machine in the step b and the data in the step a, performing theoretical calculation, and designing initial parameters;
step d: reinforcing the ground of the Australian water supply pipe;
firstly, adopting cement-water glass double-liquid slurry to carry out grouting reinforcement on a water pipe area, wherein the distance between grouting holes is 2.5 multiplied by 2.5m or 3 multiplied by 3m, and beginning grouting from the upper boundary of a non-permeable layer to the top of a sand layer; the reinforcing range is 12m-15m longitudinally relative to the central line of the water pipe in the tunnel body range, and the reinforcing range is 3m-5m from the right upper side and two sides of the tunnel to the outer side of the outer side line of the structure;
further, a grouting hole is drilled to the bottom of the tunnel within the tunnel body range, so as to find out whether the boulder exists within the tunnel range of the water supply pipe area of Australia;
then, after grouting reinforcement is completed, reserving and installing a certain number of sleeve valve pipes on a row of grouting holes which are respectively positioned at two sides of the Australian water supply pipe and close to the Australian water supply pipe; when the shield machine penetrates through the Australian water supply pipe, if the sedimentation is abnormal, the supplementary grouting is started in time;
secondly, because a layer of reinforced concrete cover plate with the thickness of about 20cm is arranged above the Australian water supply pipe, the construction of drilling holes above the cover plate is difficult, and the Australian water supply pipe is easy to disturb because the cover plate is not in place, a row of inclined holes are arranged outside the cover plate for grouting protection of the Australian water supply pipe, and the distance between the inclined holes is 1.2-1.5 m;
thirdly, because the minimum distance between the central line of the inclined hole and the water pipe is not less than 1m, for example, the diffusion radius of the inclined hole is 2.2m calculated according to the grouting pressure of 0.15Mpa, a grouting point must be properly selected when grouting the inclined hole, for example, when adopting retreating type grouting, grouting the inclined hole once every 1m, and strictly controlling the grouting pressure, so as to avoid the damage of the water pipe caused by overlarge grouting pressure;
step e: carrying out a construction test of a grouting pre-penetration pipeline;
in order to determine the construction parameters of the Australian water supply pipe for downward penetration and avoid the damage of the water pipe caused by improper parameter selection in the construction process, a test grouting pre-penetration pipeline construction test is carried out within the range of YDK2+ 886-YDK 2+895 mileage before the Australian water supply pipe is constructed; and monitoring the ground settlement during the test grouting period, and determining the reinforcing grouting parameters at the Australian water pipe according to the monitoring data condition.
The pre-through pipeline construction test is carried out in two steps:
step I, performing first-time trial grouting;
firstly, determining grouting hole arrangement and grouting parameters;
two rows of slurry are injected for the first test, 5 points are preferably selected in each row, the distance between the two rows is 3m, and the grouting mileage is respectively YDK2+887.9 and YDK2+ 890.9; grouting time of YDK2+887.9 is 1 month 4 days to 1 month 7 days, and grouting time of YDK2+890.9 is 1 month 8 days to 1 month 10 days;
then, monitoring the sedimentation in the test grouting process;
monitoring points are arranged according to requirements, and the arrangement range is that the distance in front of the position of the shield machine cutter head is 10m nearest. Monitoring the cross section spacing of 0.8m, setting 3 points on each cross section, and laying 3m deep monitoring points (the bottom elevation of the steel bar is the same as the bottom elevation of the water pipe for Australia) at the central point of the pipe piece; 1.5m shallow monitoring points (the bottom elevation of the steel bars is the same as the top elevation of the water pipe for Australia) are arranged at the central point between the pipe pieces, and the monitoring frequency is 3 times/day;
wherein, a geological drilling machine is adopted to drill holes and arrange monitoring holes, the aperture is 100 mm-108 mm, after the holes are drilled to the designed depth (3m or 1.5m), the drilling machine is moved away, a phi 50mm PVC pipe is placed in the holes, sand is filled between the PVC pipe and the hole wall to fix the PVC pipe, the backfilling depth is 1/2-2/3 of the designed depth, then a phi 18mm steel bar is placed in the PVC pipe as a monitoring point, and an initial value is obtained after the completion;
each monitoring is supervised by a specially-assigned person on site, so that the timeliness and the authenticity of monitoring data are ensured;
secondly, through analysis of ground surface monitoring data of a test grouting test section, the ground surfaces of the cross sections from 73 to 75 rings have a swelling phenomenon, the maximum swelling of the YDK2+880 cross section is 71.63mm (about 15mm including early backfill grouting swelling), and the maximum swelling of the YDK2+890 cross section is 20.10mm, so that reasonable grouting parameters and tunneling parameters are obtained;
and finally, determining the following parameters aiming at the stratum of the test section through basic construction experience and the previous grouting condition, and further performing test verification by field technicians and testers to determine reasonable construction parameters meeting the stratum: as shown in table a:
TABLE a
Step II, performing second test grouting;
repeating the contents of the loops 73 to 75 in the step I in loops 76 to 78, and re-optimizing the parameters obtained by the previous first trial grouting to make the parameters more reasonable; the Australia water supply pipe is prevented from being deformed too much in the construction process of passing through the Australia water supply pipe, so that the Australia water supply pipe is not damaged, and the normal performance of the function of the Australia water supply pipe is not influenced; in order to determine the construction parameters of grouting reinforcement at the Australian water pipe and avoid the damage of the water pipe caused by improper selection of grouting parameters in the reinforcement process,
firstly, arranging grouting holes and grouting parameters;
according to the calculation that the grouting diffusion radius is 2.3m, consideration is given to the fact that grouting reinforcement needs to be occluded, so that R is 1.5m, namely the distance between grouting holes is 3m, the tunnel excavation diameter is 8.8m, the influence range of shield construction is considered, 5 holes are arranged on each cross section, the situation of ground uplift before the grouting is considered, grouting pressure is possibly large, and therefore pressure relief holes are arranged between the grouting holes and 1.5m away from the grouting holes;
then, the arrangement range is 10m in front of the position of the cutter head of the shield tunneling machine. Each cross section is provided with 5 points, the distance between each point and each point is 3m, and the influence of grouting reinforcement on ground settlement is counted by measuring monitoring points every day;
secondly, analyzing and obtaining construction parameters of the second test grouting according to the settlement data of the first test grouting reinforcement period, the 73 rd to 75 th ring excavation conditions of the first test section and the ground settlement data of the excavation period;
for step I and step II, specifically:
after the tunneling of the upper half ring of the 73 th ring of the test section is finished, ground settlement monitoring is carried out, monitoring data show that the ground is uplifted (the maximum uplift is 12.35mm), the reason that the pressure of the soil bin is larger is obtained by analyzing tunneling parameters, the pressure of the soil bin is reduced in the rear half-ring tunneling, the ground settlement monitoring is carried out again after the tunneling is finished, and the monitoring data show that the ground uplift value is obviously reduced.
Summarizing and analyzing the ground settlement condition in the 73 rd ring tunneling process, adjusting the tunneling parameters, continuously tunneling the 74 th to 75 th rings, monitoring the ground settlement during and after the tunneling, displaying the monitoring data during the tunneling, wherein the ground has slight settlement (the maximum settlement is 2.9mm), the value is within the allowable settlement range, finely adjusting the soil pressure in the rear half ring, monitoring the ground settlement again after the tunneling, and displaying the ground settlement value to be reduced to 1.8mm by the monitoring data.
Summarizing and analyzing the ground settlement condition in the first two-ring tunneling condition, keeping parameters unchanged, continuously tunneling rings 76 to 78, monitoring the ground settlement during tunneling and after tunneling as the contents of rings 73 to 75 in the step I, displaying monitoring data during tunneling, wherein the ground has slight uplift (the maximum value is 4.05mm), the numerical value is within an uplift allowable range, finely adjusting the soil pressure in the rear half-ring tunneling, observing the ground settlement after tunneling, displaying that the ground uplift value is reduced by the monitoring data, slightly settling after the segment is separated from the shield tail, analyzing that the grouting amount is small, and accordingly, determining that the synchronous grouting amount is properly increased (changed into 14 directions) when the pipeline segment for Australia is tunneled, and keeping other parameters unchanged.
Step f: after the step e, collecting grouting parameters and tunneling parameters of fixed-section propulsion,
e, grouting and carrying out data acquisition on each monitoring point position before each propulsion test to obtain a corresponding initial value;
preferably, the fixed-segment propulsion is 800mm, namely 1/2 of the length of the segment; after the first 800mm is propelled, repeating the step d and the step e, analyzing the size rule of the cross section settlement amount and modifying the tunneling parameters in time;
according to the modified tunneling parameters, performing secondary 800mm tunneling construction, repeating the step d and the step e after the construction is passed, analyzing the size rule of the settlement of the cross section and modifying the tunneling parameters in time; and performing tunneling construction of 800mm for the third time according to the modified tunneling parameters.
Specific examples thereof;
1. grouting parameter determination
According to the calculated grouting diffusion radius of 2.3m, considering that grouting reinforcement needs to be occluded, selecting 1.5m as R, namely, the distance between grouting holes is 3 m;
the diameter of tunnel excavation is 8.8m, 5 grouting holes are arranged on each cross section according to the influence range of shield construction, pressure relief holes are arranged between the grouting holes at a position 1.5m away from the grouting holes due to the fact that the ground of the shield is raised before, and grouting pressure is possibly large, and the specific layout is shown in fig. 3;
and analyzing and obtaining initial construction parameters of test grouting of rings 76 to 78 according to the settlement data during the first test grouting reinforcement period and the ground settlement data during the 73 th to 75 th ring excavation period of the first test section. The grouting parameters of the test section are shown in table 1.
TABLE 1 grouting parameters for pre-through pipe line construction test
Step g: tunneling parameter determination
The tunneling parameters are the optimal parameters which have the minimum disturbance to the soil body and the minimum sedimentation and are obtained in the two-step test tunneling process as well as the determination of the grouting parameters. Specific partial excavation parameters are shown in table 2.
According to reasonable grouting parameters and tunneling parameters obtained in the construction test of the pre-penetration pipeline, the construction of the Australian water supply pipe for downward penetration is carried out, each monitoring point is still monitored in real time in the tunneling construction process, the settlement deformation condition is strictly observed, and the whole process of the Australian water supply pipe for downward penetration of the shield is as shown in figure 4.
Table 2 partial construction driving parameter summary table
TABLE 3 Settlement control value criteria
Analysis of monitoring results
1. The monitoring items are as follows
1) The settlement change of each cross section at the position with the depth of 3m of the soil body when the cutter head and the shield tail pass through the water supply pipe for Australia.
2) The settlement change of each cross section at the position with the soil depth of 1.5m when the cutter head and the shield tail pass through the water supply pipe for Australia.
2. Monitoring criteria and data
The Australian water supply pipe is easy to damage in the long term, so the settlement control standard of the surrounding soil body is adjusted. The specific sedimentation control criteria are given in table 3.
3. Monitoring results
The sedimentation deformation curves during the period when the cutter head passes through the water supply pipe at the depth of 3m and the period when the shield tail passes through the water supply pipe at the depth of 1.5m are shown in FIGS. 4-5.
In conclusion, in the process of newly building a shield tunnel from the pearl sea urban area to the pearl sea airport intercity rail traffic project from north arch to the violin section, and passing through a water supply pipe, the maximum deformation of the cutter head of each monitoring point position with the depth of 3m is 6.8mm when the cutter head passes through the water pipe, and the maximum deformation of the shield tail is 6.98mm when the shield tail passes through the water pipe; the maximum deformation of each monitoring point position cutter head of the depth 1.5m when passing through the water pipe is 5.7mm, the maximum deformation of the shield tail when passing through the water pipe is 6.74mm, and the maximum deformation of all the point positions during the period of downwards penetrating the water pipe for feeding Australia is far lower than the control standard of the construction requirement.
Step h, optimizing the modified grouting parameters and tunneling parameters according to the step g, and enabling the shield tunneling machine to penetrate through the Australian water supply pipe; the method comprises the following specific steps:
(1) according to the determined tunneling parameters, the soil output is strictly controlled, the sufficient synchronous grouting amount is ensured, meanwhile, a skilled assembling hand is arranged to accelerate the assembling speed of the pipe piece, and the pipe piece quickly and evenly passes through the water supply pipe area; when the water is pushed to pass through the lower part of the water pipe, one water pipe can be cut off for no more than 3 hours according to the requirement.
(2) Soil improvement
The geological conditions of the stratum penetrated by the shield tunnel are uneven, and a sandy soil body and the uneven stratum are improved by injecting additive materials (foam, bentonite and the like) according to the stratum condition in the construction process; after the soil body is improved by injecting the additive material, the excessive settlement of the earth surface can be controlled.
improving the workability and seepage-proofing property of soil body
The additive material is injected into the excavation surface and the soil bin, and the residue soil is changed into the soil with plasticity, fluidity and seepage resistance through stirring, and the soil bin and the screw conveyer are filled with the soil. When the pressure in the soil bin is smaller than the pressure of the excavation surface, the dregs on the excavation surface continuously enter the soil bin, the soil pressure in the soil bin is increased, the pressure balance of the soil inside and outside the excavation surface is achieved, the stratum in front of the excavation surface is stabilized, and the deformation of the stratum is controlled. The full soil pressure is kept in the segment assembling process.
After the additive material is injected, the viscosity of the soil body with strong permeability can be improved, the permeability coefficient of the soil body is reduced, when the soil body subjected to improvement treatment is full of the pressure bin, the active effect of preventing the underground water of the excavation surface from permeating and reducing the water loss and settlement of the stratum is achieved, meanwhile, the occurrence of a gushing accident can be prevented, and the construction safety is ensured.
secondly, reducing the torque of the cutter head and reducing the failure rate of machinery
The injected additive material has the lubricating effect while improving the soil workability, can reduce the cutter torque in the shield tunneling, enables the shield tunneling machine to be always in a good mechanical state for construction operation, reduces the mechanical failure rate and ensures the continuity of tunneling construction.
(3) Rational arrangement of construction plans
When a circulating construction progress plan is arranged, the time of main construction processes such as tunneling, unearthing, segment assembling and the like is distributed, the time of measurement and segment waiting is shortened as much as possible, the transportation efficiency is improved, continuous construction of an operation surface is maintained, the underground transportation of segment materials is organized according to a segment assembling sequence determined by calculation in time, and segment assembling operation is accelerated.
The shield machine propulsion speed is controlled, the construction progress of each ring is approximately balanced, large differential settlement of the earth surface caused by uneven propulsion speed is prevented, and disturbance of the soil body and segment deformation are reduced.
(4) Ensure the quality and the manufacturing precision of the duct piece
The segment manufacturing precision and impermeability meet the design and standard requirements, segment joints are constructed strictly according to the design requirements to be waterproof, segment assembling quality and joint waterproof effect are ensured, underground water infiltration is reduced, and meanwhile, connecting bolts are fastened fully to avoid segment lining deformation and soil deformation.
(5) Intensified grouting amount
And (3) performing secondary grouting in time after each ring of tunneling and assembling is completed, and performing wall back double-liquid grouting by adopting cement and water glass slurry in order to reduce ground deformation and control the uneven settlement amount of the foundation. And the secondary grouting controls the grouting amount and the grouting pressure well, reduces the disturbance to the stratum and prevents the foundation from uplifting due to overlarge grouting pressure.
Step j, monitoring and measuring the scheme on the ground;
during grouting construction and when a shield is propelled to pass through a reinforced area, particularly a Australian water pipe, reinforcement and shield passing, accurate monitoring data are timely provided through tracking monitoring, monitoring frequency is adjusted according to actual conditions on site, monitored arrangement points are controlled according to the regional monitoring scheme so as to accurately grasp tracking grouting opportunity, area and tracking grouting ending control, and the phenomenon that local grouting amount is too large due to random grouting and the ground is raised or a water pipe joint is dislocated is avoided.
And reinforcing steel bars are embedded in the vertical displacement points. According to specific conditions, drilling a hole in a ground concrete pavement or an asphalt pavement to a sand layer, wherein the diameter of the drilled hole is 5cm, a pvc sleeve with the diameter of 5cm is installed, reinforcing steel bars are embedded in the sleeve to a depth of the original sand layer, and the top of the pvc sleeve is slightly lower than the ground. And embedding the observation mark into the original soil layer, and pouring sand into the hole. The observation mark head should be 3-5 mm lower than the road surface (ground surface), and the point number is marked with red paint beside the observation mark head.
The ground monitoring points of the Australian water supply pipe are arranged together with the reinforced ground monitoring points, and the Australian water supply pipe spans south gulf. The south gulf south road is that the main trunk road traffic flow in urban area is fairly big, therefore excavate the exposure water pipe in greenbelt (do not influence the traffic) central point, lays 2 monitoring points and monitors the water pipe on the water pipe. And (3) setting a monitoring point at 0.5m on one side of the position of the water pipe joint, drilling a hole with the diameter of 5cm, installing a pvc sleeve with the diameter of 5cm, and embedding the reinforcing steel bar into the sleeve to a depth of the original sand layer. Sand is poured into the hole, and the observation mark head is 3-5 mm lower than the road surface (ground surface). And measuring the monitoring frequency according to a monitoring scheme or carrying out encryption adjustment according to the specific construction condition. And (4) when grouting and reinforcing the Australian water supply pipe stratum and the shield machine passes through the Australian water supply pipe, encrypting on the basis of the original monitoring frequency (monitoring every 4 h).
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; it is obvious as a person skilled in the art to combine several aspects of the invention. And such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.