Disclosure of Invention
The invention aims to provide a construction method for downwards penetrating a super-large bridge by using a shield machine, which solves the existing problems: the shield interval often has the construction risk when passing through an oversize bridge.
In order to solve the technical problems, the invention is realized by the following technical scheme:
the invention relates to a construction method for downward penetrating a super-large bridge by using a shield tunneling machine, which comprises the following steps:
compiling a corresponding underpass scheme;
monitoring points are arranged on the bridge pavement and in the tunneling direction of the shield tunneling machine;
leveling and reinforcing the road surface in the tunneling direction range near the bridge body, and flattening the foundation bearing platform;
drilling holes on the basic bearing platform by a drilling machine, drilling pipe holes, and washing the pipe holes properly;
manufacturing sleeve valve pipes according to the pipe holes, and filling the manufactured sleeve valve pipes into the pipe holes;
and in the tunneling process of the shield tunneling machine, grouting is carried out in real time through the sleeve valve pipe according to the condition of the monitoring point.
Further preferably, wherein the monitoring points are arranged on the bridge body road surface and in the driving direction of the shield tunneling machine, the monitoring points mainly comprise:
arranging small end faces every 5m along the center line in the tunneling direction, and arranging 1 monitoring point on each small end face; every 10 meters is provided with a big end face, and each big end face is provided with 5 monitoring points.
Further preferably, the monitoring points are used for detecting pavement settlement, horizontal displacement and horizontal displacement of deep foundation layers.
More preferably, the sleeve valve pipe is a PVC sleeve valve pipe with the diameter of 50mm, a group of grout spraying holes with the diameter of 8mm are drilled on the sleeve valve pipe every 33 cm-35 cm, and the longitudinal distribution length of each group of grout spraying holes is 6 cm-10 cm.
Further preferably, the outer part of each group of grout injection holes is wrapped with 1 layer of rubber sleeve, and the length of the rubber sleeve is longer than that of each group of grout injection holes.
More preferably, the real-time grouting is grouting by using pure cement slurry of 42.5R ordinary portland cement, and the water-cement ratio is 0.6-1.0. .
The invention has the following beneficial effects:
the method adopts a repeated circulation sleeve valve pipe grouting reinforcement measure, can repeatedly perform grouting, and performs a later-stage settlement control measure according to risk settlement monitoring.
The sleeve valve pipe is made of the material of the circularly repeated sleeve valve pipe, so that the traditional backfill type embedded sleeve valve pipe is changed, and the economic cost and the economic expenditure are greatly controlled. The engineering material cost is reduced, and the cost is saved.
The novel characteristic material of the repeated sleeve valve pipe is adopted, so that the later-stage re-punching and pre-embedding time is shortened, and the later-stage processing work efficiency is improved.
According to the invention, deep hole grouting is carried out in the hole to reinforce the surrounding soil body, so that the stability of the bottom layer is greatly improved.
The construction method greatly reduces the influence of shield construction on the existing operation line, reduces the settlement of surrounding buildings, ensures the safety of surrounding roads and obtains great social and economic benefits.
The method adopts automatic monitoring, greatly simplifies the measurement procedure, reduces the workload of measurement personnel, accurately obtains the monitoring data in real time and obtains better technical benefit compared with the traditional monitoring method.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1, the present invention is a construction method for passing a super-large bridge downward by using a shield tunneling machine.
1. Preparation for construction
Corresponding underpass schemes are compiled according to technical characteristics before construction, bridge pile foundations are analyzed and calculated, technical parameters required by operation are determined, and safety construction technology bottom crossing is carried out according to field operation personnel.
According to the actual conditions, a proper geological drilling machine, a grouting pump, a slurry pump, a stirring machine and a cutting machine are selected, equipment inspection is carried out in advance, normal operation is guaranteed, and equipment controllability, safety and controllability are achieved.
And (4) preparing consumable materials such as a sleeve valve pipe, a wire, a bolt, cement and the like for repeated grouting, obtaining a product inspection certificate, and controlling the materials.
2. Placement construction monitoring
Monitoring points are arranged on the bridge pavement and in the tunneling direction of the shield tunneling machine;
monitoring points in the range of the lower-crossing viaduct are distributed as follows: along the central line of the tunneling direction, 5 meters of small section (1 monitoring point of the small section) and 10m of large section (5 monitoring points of the large section) are arranged; and laying settlement observation points and horizontal displacement observation points on the bridge piers in the range influenced by the shield, and burying the horizontal displacement of the deep layer of the foundation.
3. Sleeve valve tube positioning
Firstly, leveling and reinforcing the road surface in the tunneling direction range near the bridge body, and flattening a foundation bearing platform;
positioning the sleeve valve pipe on the basic bearing platform and marking;
drilling holes in the marks by using a drilling machine, drilling pipe holes, and washing the pipe holes properly;
the drilling angle error is less than or equal to 3%, the drilling depth error is less than or equal to 50mm, and the drilling depth of the anchor rod is greater than 0.3-0.5 m in design.
And tracking grouting by using a sleeve valve pipe when the three-loop bridge pile is laterally penetrated, completing sleeve valve pipe construction before the shield tunnel penetrates, and considering whether grouting is performed or not according to a monitoring result. And if the deformation of the bridge piles and the bearing platforms reaches the early warning value of the control standard in the tunnel crossing process, starting grouting measures in the grouting ground and the holes.
4. Manufacture and installation of sleeve valve tube
Manufacturing sleeve valve tubes according to the tube holes;
by using
The PVC sleeve valve pipe retreats to carry out layered grouting construction, and a group of the PVC sleeve valve pipes are drilled on the sleeve valve pipe every 33-35 cm
The longitudinal distribution length of each group of the slurry shooting holes is 6 cm-10 cm. The outer part of each group of grout injection holes is wrapped with 1 layer of rubber sleeve, the length of the rubber sleeve is slightly longer than that of each group of grout injection holes, and the principle of wrapping the grout injection holes is taken.
And the sleeve valve tube is arranged in the tube hole.
5. Grouting construction
And in the tunneling process of the shield tunneling machine, grouting is carried out in real time through the sleeve valve pipe according to the condition of a monitoring point, and the grouting adopts pure cement slurry of 42.5R ordinary portland cement, and the water cement ratio is 0.6-1.0. The additive can be mixed in a proper amount, and the lap joint of the reinforcing body is not allowed to have blank areas. The grouting pressure is preferably determined through a grouting test, and is preliminarily drawn up to be 0.6-1 MPa according to experience. And (5) checking whether the hole is full of grout about 1 hour after grouting. If the soil is not full, the filling is carried out to ensure that the grouting is full, and backfill stones and loose soil layers are penetrated to achieve the reinforcement effect. Prevent the cavity that produces because of the grout solidification shrinkage. The cement slurry requires the use of tap water, ordinary portland cement. The grout is stirred uniformly, the grout is used along with stirring, the grout is used up before initial setting, stone blocks and impurities are prevented from being mixed into the grout strictly, and when grouting operation is started and stopped for a long time again in midway, a grouting pipe and a grouting pump need to be lubricated by water or dilute grout.
Because the sleeve valve pipe grouting is pipeline pressure grouting, and pure cement mortar has better grouting property and permeability than cement mortar, the sleeve valve pipe grouting is generally performed by pure cement mortar, and if the mortar is used, the mixing amount of sand is less than 30 percent (accounting for the using amount of cement). And (5) plugging the pipe orifice after grouting is finished.
The grouting pressure is controlled to be 0.2-0.3MPa, and the grouting pressure is strictly controlled.
6. Reinforcement detection index
The number of the reinforcing detection points is preferably 1% of the number of the construction holes, and is not less than 3 points. The detection method adopts a mode of combining dynamic sounding and static sounding, and can also adopt a coring verification mode when necessary, wherein the dynamic sounding indexes are as follows: the reinforcing body should meet the dynamic penetration test N63.5, and the corrected average value of the hit number is not less than 25 hits; static sounding indexes: static cone penetration test for 28 days: the Ps value of plain filling soil is more than 2MPa, the Ps value of silty clay is more than 6MPa, the Ps value of medium and fine sand is more than 5MPa, and the Ps value of round gravel is more than 10 MPa. Reinforcing body strength index: the unconfined compressive strength of 28d is more than or equal to 0.5 MPa.
To further illustrate the process of the present invention, materials and equipment according to the present invention are first provided as follows:
construction equipment and material table
The principle of the method of the invention is as follows:
in the section, sleeve valve pipes are adopted to track grouting when the super-huge type three-ring overhead bridge piles are penetrated downwards, sleeve valve pipe construction is completed before the shield tunnel penetrates through the section, and whether grouting is performed or not is considered according to monitoring results. And if the deformation of the bridge piles and the bearing platform reaches the early warning value of the control standard in the tunnel crossing process, starting grouting.
During the period that the shield penetrates through the bridge pile foundation, deep hole grouting and synchronous grouting are needed in the hole, grouting pressure is low, insufficient grouting amount can lead to poor reinforcing effect, settlement of the earth surface is caused, and the pile foundation is inclined. The too big ground uplift that can lead to of slip casting volume and slip casting pressure, the pile foundation warp, also can influence the firm slope even of pile foundation. PVC sleeve valve pipes which can be repeatedly grouted with phi 50 are pre-embedded at the periphery of the viaduct pile foundation, pre-grouting reinforcement is carried out on the sleeve valve pipes before the shield arrives, and during grouting, multipoint balanced and synchronous grouting is needed, so that disturbance to the pile foundation is reduced to the minimum. And carrying out deep hole tracking grouting reinforcement according to the monitoring condition during shield crossing, and controlling the settlement and deformation of the pile foundation.
Besides ground reinforcement of the three-ring viaduct, the settlement and inclination monitoring of the viaduct pile foundation is enhanced during and before the shield passes through the three-ring viaduct and the four-new south viaduct, reinforced reinforcing duct pieces are adopted in the side-passing range, and grouting holes are additionally arranged to perform deep hole grouting reinforcement in the hole. The grouting reinforcement directions of deep holes in the left line hole and the right line hole of the three-ring viaduct are all 360-degree full-section grouting reinforcement, the reinforcement radius is the sum of static water pressure and soil pressure which are required to be higher than the point when synchronous grouting is carried out 3 meters beyond the outer wall of the duct piece, and the grout is filled as far as possible and is not suitable for splitting. The grouting pressure is too high, the soil layer outside the pipe wall is disturbed by the grout to cause the surface of the earth to bulge, and grout leakage is easily caused in a shallow-buried section; and the grouting pressure is too low, the slurry filling speed is too low, and the surface sedimentation is increased due to insufficient filling. According to calculation and experience, the grouting pressure value of the engineering is as follows: 0.2 to 0.3 MPa.
From the above, it can be seen that the present invention has the following benefits:
benefit analysis
By adopting a material structure of 'sleeve valve pipes for repeated grouting' and grouting in holes, the construction method for the overhead side-through of the bridge is applied to the engineering, so that the probability of stratum settlement is greatly controlled, zero settlement penetration is realized, the cost of secondary reinforcing materials is saved, the labor input is saved, and the investment of construction machinery is saved.
The construction method greatly reduces the influence of shield construction on the existing operation line, reduces the settlement of surrounding buildings, ensures the safety of surrounding roads and obtains great social and economic benefits.
The method adopts automatic monitoring, greatly simplifies the measurement procedure, reduces the workload of measurement personnel, accurately obtains the monitoring data in real time and obtains better technical benefit compared with the traditional monitoring method.
In the description herein, references to the description of "one embodiment," "an example," "a specific example" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The preferred embodiments of the invention disclosed above are intended to be illustrative only. The preferred embodiments are not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best utilize the invention. The invention is limited only by the claims and their full scope and equivalents.