An ultra-shallow burying depth shield construction method and device

Abstract

The present application relates to a kind of ultra-shallow soil covering depth shield construction method and device, it is related to the field of tunnel engineering, it is applicable to in ultra-shallow soil covering depth condition, how shield is originated or arrived during, while reducing the adverse effects of shield tunneling to surrounding environment in the guarantee of tunnel engineering safety.That is, in ultra-shallow soil covering depth, to reduce the influence of shield machine face water and soil pressure on surrounding strata, the combination mode of prestressed reinforced concrete slab, uplift pile is set in advance on ground and covered above shield, artificially increase additional vertical load of shield tunnel upper portion, lateral face pressure, thereby play the effect of increasing soil, the influence on surrounding during shield tunnel construction is reduced to minimum.Can solve the technical problem of shield tunnel safety originating, surrounding environmental impact controllable under the condition of ultra-shallow soil covering depth, expand the selection range of shield originating well, the length of shield machine excavation is maximized, thereby reducing the cost of shield machine.

Description

Technical Field

[0001] This invention relates to the field of tunnel engineering, and in particular to a method and apparatus for constructing shield tunnels with extremely shallow overburden depths. Background Technology

[0002] With the rapid development of domestic rail transit and river-crossing tunnels, the shield tunneling method is gaining an increasingly important place in tunnel engineering due to its advantages such as high speed, high safety, and minimal impact. During the construction of shield tunnels, the initial stage of shield launching is a high-risk period because the overburden is shallow, making it difficult to control the water and soil pressure at the tunnel face. Even slight mishaps can cause uplift or subsidence, affecting the safety of surrounding buildings and structures. Generally, the location of the launching shaft must be chosen according to the requirement that the minimum overburden thickness of the tunnel be no less than 0.5D. Otherwise, if the overburden is too shallow, the water and soil pressure at the tunnel face can easily break through the water and soil pressure in front of the tunnel machine, causing ground deformation. In severe cases, this can affect the safety of surrounding underground pipelines and surface buildings.

[0003] In existing technologies, when the overburden above the tunnel is shallow, temporary measures such as earthwork surcharge and steel plate ballast are usually used to increase the water and soil pressure at the tunnel face during shield tunneling, so as to reduce the deformation of the surrounding strata caused by shield tunneling and thus reduce the difficulty of shield construction control.

[0004] However, in practical engineering applications, such measures require temporary requisition or closure of land above the tunnel, excavation of the existing overburden above the tunnel, pouring of anti-uplift piles and Miller plates, followed by backfilling. If located beneath a road, this would disrupt traffic for an extended period and necessitate relocation of pipelines before implementation, potentially causing uneven settlement of existing underground pipelines and road surface structures. Furthermore, these measures require the prior installation of working shafts, pipe jacking, MJS reinforcement, long piles, and anti-buoyancy plates before tunnel boring machine (TBM) advancement, involving numerous procedures and high investment costs. The long piles and anti-buoyancy plates, once installed on the ground, only function when the ground compresses them upwards, making ground settlement control during TBM excavation relatively more difficult. Therefore, in practical engineering, measures such as earthwork loading and steel plate ballast have certain limitations.

[0005] Therefore, it is necessary to study a method and device for ultra-shallow overburden shield tunneling to ensure the safety of the shield tunnel and the surrounding environment. Summary of the Invention

[0006] The purpose of this invention is to provide a method and apparatus for shield tunneling with ultra-shallow overburden depth, which can solve the technical problems of safe starting of shield tunnels and controllable impact on the surrounding environment under ultra-shallow overburden depth conditions, expand the selection range of shield starting shafts, maximize the tunneling length of the shield machine, and thus reduce the amortization cost of the shield machine.

[0007] To achieve the above object, the present application designs a kind of ultra-shallow soil covering buried depth shield construction method, the method comprises the following steps:

[0008] Pre-fabrication production multiple concrete plates and multiple uplift piles in factory, after reaching strength standard, transport to construction site;

[0009] Clean up the site on both sides of the ultra-shallow soil covering tunnel, pour sand cushion, and fill the ground above the tunnel;

[0010] Buried earth pressure gauge and water level monitor in the tunnel;

[0011] Erect each concrete plate on sand cushion, and install uplift pile and jack on each concrete plate respectively to form multiple counterforce support assemblies;

[0012] Use static pressure equipment to extrude the uplift pile in each counterforce support assembly into the lower stratum of the tunnel, and control the water and soil pressure of the shield machine face to about 0.5D;

[0013] Adjust the water and soil pressure of the shield machine face in time according to the earth pressure value monitored by earth pressure gauge and the water level value monitored by water level monitor, and carry out shield tunneling construction, assemble segments to form shield tunnel.

[0014] As a preferred scheme, the calculation method of the transverse length of the concrete plate is L=(h+(√2+1)D+t)*2, wherein L is the transverse width of the concrete plate, h is the tunnel buried depth, D is the tunnel outer diameter, and t is the lateral allowance.

[0015] As a preferred scheme, the water and soil pressure of the shield machine face = soil pressure + water pressure + pre-pressure + additional stress, the soil pressure is the horizontal direction soil pressure in front of the shield machine face, the water pressure is the pore water pressure of the face, the pre-pressure is an empirical value of 20-30kPa, and the additional stress is the vertical load of the uplift pile transmitted to the prestressed reinforced concrete structure plate and the self weight of the structure plate.

[0016] The present application also designs a kind of ultra-shallow soil covering buried depth shield construction device, the device comprises concrete plate, uplift pile, jack, earth pressure gauge and water level monitor;The concrete plate, uplift pile and jack together form a counterforce support assembly;The earth pressure gauge and water level monitor are buried in the shield tunnel respectively to monitor the earth pressure value and water level value.

[0017] As a preferred scheme, the structure size of each concrete plate is uniform, the thickness of the structure plate is controlled according to 200-600mm, the transverse length is considered comprehensively according to the tunnel buried depth and tunnel diameter, and the longitudinal block length is controlled according to 2000-3000mm;Two holes are reserved on each concrete plate, and the diameter of the hole is 50-100mm larger than the diameter of the uplift pile.

[0018] As a preferred solution, in order to facilitate the control of the water and soil pressure of the tunneling face of the shield machine, the concrete plates and the uplift piles are arranged on the ground in sections, and different vertical loads are arranged on each concrete plate, so that the water and soil pressure of the tunneling face of the shield machine is controlled at about 0.5D.

[0019] The present application has the following beneficial effects:

[0020] The present application relates to the field of tunnel engineering, and is suitable for reducing the adverse effects of shield tunneling on the surrounding environment while ensuring the safety of the tunnel engineering under the condition of super-shallow overburden depth during the starting or arrival of the shield. That is, under the condition of super-shallow overburden depth, in order to reduce the influence of the water and soil pressure of the tunneling face of the shield machine on the surrounding stratum, a combination of prestressed reinforced concrete plates and uplift piles is arranged on the ground in advance to cover the shield machine, the additional vertical load and the lateral tunneling face pressure of the shield tunnel are artificially increased, so that the effect of increasing the overburden is achieved, and the influence of the shield tunnel construction on the surrounding environment is minimized.

[0021] The present application has the following beneficial effects:

[0022] The present application has the following beneficial effects: BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The flowchart of the present application;

[0024] Figure 2 The horizontal section view of the auxiliary measures for shield construction of the present application;

[0025] Figure 3 The longitudinal section view of the auxiliary measures for shield construction of the present application;

[0026] Figure 4 The three-dimensional structure diagram of the counterforce support assembly;

[0027] Explanation of reference signs:

[0028] 1 concrete slab, 2 uplift pile, 3 jack, 4 shield tunnel, 5 counterforce support assembly, 6 earth pressure cell, 7 water level monitor. DETAILED DESCRIPTION

[0029] In order to make the technical problems solved by the present application, the technical solutions adopted and the technical effects reached more clear, the technical solutions of the present application will be further described below in conjunction with the accompanying drawings and specific embodiments. It can be understood that the specific embodiments described here are only used to explain the present application, but not limit the present application. In addition, it should be noted that, for the convenience of description, only the parts related to the present application are shown in the drawings, not all.

[0030] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions.

[0031] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0032] The present application relates to a kind of ultra-shallow soil covering depth shield construction method and device, it is applicable to the ultra-shallow soil covering depth condition of 0.5D (D is shield tunnel outer diameter) And below, during shield originating or reaching, while guaranteeing the safety of tunnel engineering, reduce the adverse effect of shield tunneling to surrounding environment.That is, when ultra-shallow soil covering depth, to reduce the influence of shield machine face water and soil pressure on surrounding stratum, reduce the difficulty of shield machine face water and soil pressure control, prestressed reinforced concrete slab is set in advance on ground, uplift pile, through the combination structure covering on shield, artificially increase the additional vertical load of shield tunnel upper portion, increase the face pressure in front of shield machine, to increase the effect of soil covering, the influence on surrounding during shield tunnel construction is reduced to a minimum.The method of the present application can realize the safe originating or reaching of shield tunnel under the condition of ultra-shallow soil covering depth, the influence on surrounding environment is controllable, in addition, the selection range of shield originating well can be expanded, the length of shield machine excavation is maximized, so as to reduce the cost of shield machine.The present application can be applicable to shield originating, reaching or intermediate ultra-shallow soil covering depth shield tunnel engineering in various ultra-shallow soil covering depths, and can also be applicable to pipe jacking tunnel engineering.

[0033] As Figure 1 The method of the present application comprises the following steps:

[0034] Step one: prefabricate multiple concrete slabs 1 and multiple uplift piles 2 in factory, and transport to construction site after reaching strength standard.

[0035] Step two: clean up the site on both sides of ultra-shallow soil covering tunnel, pour sand cushion layer, and fill the ground on the upper portion of tunnel to make the load on the upper portion of tunnel evenly transmitted to the lower stratum.

[0036] Step three: bury soil pressure gauge 6 and water level monitor 7 in tunnel.

[0037] Step four: erect each concrete slab 1 on sand cushion layer, then install uplift pile 2 and jack 3 on each concrete slab 1 respectively to form multiple counter-force support assemblies 5. In this way, the force transmission can be better.

[0038] Step five: use static pressure equipment to extrude uplift pile 2 in each counter-force support assembly 5 into the lower stratum of tunnel, and control the shield machine face water and soil pressure to about 0.5D.

[0039] Step six: adjust the shield machine face water and soil pressure in time according to the soil pressure value monitored by soil pressure gauge 6 and the water level value monitored by water level monitor 7, and shield machine advances, assembles segments to form shield tunnel 4.

[0040] As Figures 2 to 4As shown, the device of the present application comprises a concrete slab 1, a uplift pile 2, a jack 3, a earth pressure gauge 6, a water level monitor 7; wherein the concrete slab 1, the uplift pile 2 need to be prefabricated in advance in the factory, the concrete slab 1, the uplift pile 2, the jack 3 together constitute a counterforce support assembly 5; the earth pressure gauge 6, the water level monitor 7 are respectively buried in the shield tunnel 4, for monitoring the earth pressure value, the water level value, facilitating timely adjustment of the shield machine face water and soil pressure. For the convenience of shield machine face water and soil pressure control, through the prestressed reinforced concrete slab, the uplift pile and other structural measures arranged on the ground in sections, different vertical loads are arranged on each prestressed reinforced concrete slab, so as to control the shield machine face water and soil pressure at about 0.5D.

[0041] The concrete slab 1 is a prestressed reinforced concrete slab, which is relatively light in structure, and the structural size of the concrete slab 1 is generally controlled according to the structural stress requirement, because the thickness of the prestressed reinforced concrete slab is thinner than that of the reinforced concrete slab, which is beneficial to on-site hoisting, therefore, the factory prefabrication method is adopted, and both the pretensioning method and the post-tensioning method can be used. Considering the rapid construction and the replaceability of the components, the structural size of each prestressed reinforced concrete slab is uniform, and the structural slab thickness is generally controlled at 200-600mm, the horizontal length is comprehensively considered according to factors such as the tunnel burial depth, the tunnel diameter, and the longitudinal block length can be controlled at 2000-3000mm. Two holes are reserved on each prestressed reinforced concrete slab, and the hole diameter is 50-100mm larger than the diameter of the uplift pile 2, which is beneficial to on-site assembly.

[0042] The horizontal length calculation method of the concrete slab 1 is as follows:

[0043] The influence range of various strata is different, considering the ultra-shallow overburden working condition, the stratum parameters are relatively poor, in order to facilitate calculation, the following conditions are calculated:

[0044] 1. The lateral allowance of the two side structural slabs is controlled at 0.5-1.0m, which is determined according to the diameter of the shield, and the larger value is taken when the diameter is large, and the smaller value is taken when the diameter is small;

[0045] 2. The shield tunneling angle is A, and it is assumed that the influence range of the shield tunneling is controlled at the most unfavorable 45° angle;

[0046] Then L=(h+(√2+1)D+t)*2;

[0047] Wherein, L is the horizontal width of the concrete slab 1, h is the tunnel burial depth, D is the outer diameter of the tunnel, and t is the lateral allowance.

[0048] The longitudinal arrangement range of the concrete slab 1 is that the overburden thickness above the tunnel is 0-0.5D.

[0049] The anti-pulling pile 2 can adopt a prefabricated pipe pile as a finished component, which is extruded into the stratum by using a static pressure equipment on the ground. In order to facilitate the transmission of the counterforce between the anti-pulling pile 2 and the concrete slab 1, an enlarged end is arranged at the top of the anti-pulling pile 2, which is similar to the enlarged head of the nail type anti-pulling pile, so as to serve as the fulcrum of the counterforce of the concrete slab 1. The length of the anti-pulling pile 2 is determined according to the specific calculation of the structural stress requirement.

[0050] Four jacks 3 are arranged in the gap between the top of the nail type anti-pulling pile 2 and the concrete slab 1, which are used for adjusting the vertical additional stress transmitted to the stratum and can also increase the stratum pressure.

[0051] In order to facilitate the real-time monitoring of the additional stress in the stratum, a soil pressure gauge 6 and a water level monitor 7 and other facilities are laid under each block of prestressed reinforced concrete slab, so as to timely adjust the force of the jack 3 and also can real-time master the stratum stress distribution, which is better matched with the shield construction parameters.

[0052] By arranging different vertical loads on each block of the concrete slab 1, the water and soil pressure of the shield machine working face can be additionally increased, and finally the water and soil pressure of the shield machine working face is controlled at about 0.5D, wherein D is the outer diameter of the shield tunnel, and the water and soil pressure 0.5D is kPa, so as to achieve the effect of increasing the overburden thickness above the shield.

[0053] Without the measures of the present application, the water and soil pressure of the shield machine working face = soil pressure + water pressure + pre-pressure, which can generally be controlled according to the top or bottom of the tunnel. Since there is a certain height difference at the top and bottom of the shield machine, there is a certain excess water and soil pressure at the top or bottom of the shield machine working face, which is the reason for the stratum uplift or settlement.

[0054] After the measures of the present application are taken, the water and soil pressure of the shield machine working face = soil pressure + water pressure + pre-pressure + additional stress. Due to the existence of the additional stress, the water and soil pressure of the shield machine working face can be increased, and the proportion of the excess water and soil pressure is reduced, so it is beneficial to control the stratum deformation.

[0055] The soil pressure is the horizontal soil pressure in front of the shield machine working face, which can be calculated by various methods such as active soil pressure, static soil pressure and relaxation soil pressure, and is determined according to the stratum condition.

[0056] The water pressure is the pore water pressure of the working face, which is determined according to the underground water level in the theoretical calculation.

[0057] The pre-pressure generally considers the setting error of the underground water pressure and the soil pressure, as well as the factors such as the soil pressure and water pressure variation in the equipment, and is determined according to experience, and is generally 20-30 kPa.

[0058] Additional stress, for the uplift pile to prestressed reinforced concrete structure plate and the vertical load of the structure plate self weight.

[0059] The above-described embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it cannot be understood as limiting the scope of the patent of the present application. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, several modifications and improvements can be made, which belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. An ultra-shallow cover depth shield construction method, characterized by: The method comprises the following steps: Pre-fabricate multiple concrete plates and multiple uplift piles in a factory, and transport them to a construction site after reaching the strength standard; Clean up the site on both sides of the tunnel with ultra-shallow buried soil, pour a sand cushion layer, and fill the ground above the tunnel; Embed a soil pressure gauge and a water level monitor in the tunnel; Erect each concrete plate on the sand cushion layer, and install an uplift pile and a jack on each concrete plate to form multiple counterforce support assemblies; Use static pressure equipment to extrude the uplift pile in each counterforce support assembly into the ground layer below the tunnel, and control the water and soil pressure on the tunnel face of the shield machine to be about 0.5D; Adjust the force of the jack and the water and soil pressure on the tunnel face of the shield machine in a timely manner according to the soil pressure value monitored by the soil pressure gauge and the water level value monitored by the water level monitor, and perform shield tunneling construction, assemble segments, and form a shield tunnel.

2. The ultra-shallow cover depth shield construction method according to claim 1, characterized in that: The calculation method of the transverse length of the concrete plate is ， wherein L is the transverse length of the concrete plate, h is the tunnel depth, D is the tunnel outer diameter, and t is the lateral allowance.

3. The ultra-shallow cover depth shield construction method according to claim 2, characterized in that: The water and soil pressure on the tunnel face of the shield machine = soil pressure + water pressure + pre-pressure + additional stress, the soil pressure is the horizontal soil pressure in front of the tunnel face of the shield machine, the water pressure is the pore water pressure on the tunnel face, the pre-pressure is an empirical value of 20-30 kPa, and the additional stress is the vertical load transmitted by the uplift pile to the pre-stressed concrete plate and the self-weight of the concrete plate.

4. A construction device based on the ultra-shallow burying depth shield construction method of claim 1, characterized in that: The device comprises a concrete plate, an uplift pile, a jack, a soil pressure gauge, and a water level monitor; the concrete plate, the uplift pile, and the jack together form a counterforce support assembly covering the shield machine, which is used to increase the additional vertical load on the shield tunnel and the lateral tunnel face pressure, thereby increasing the soil covering effect and minimizing the impact on the surrounding environment during shield tunnel construction; the soil pressure gauge and the water level monitor are embedded in the shield tunnel, and are used to monitor the soil pressure value and the water level value, and comprehensively adjust and optimize the construction parameters of the shield machine and the pressure of the ground jack to control the shield machine, ensure the safety of the tunnel project, and reduce the adverse impact of shield tunneling on the surrounding environment.

5. The apparatus for the ultra-shallow burying depth shield construction method according to claim 4, characterized in that: The structural size of each concrete plate is uniform, the thickness of the concrete plate is controlled to be 200-600 mm, the transverse length is comprehensively considered according to the tunnel depth and the tunnel diameter, and the longitudinal block length is controlled to be 2000-3000 mm; two holes are reserved on each concrete plate, and the diameter of the holes is 50-100 mm larger than the diameter of the uplift pile.

6. The apparatus for the ultra-shallow covering depth shield construction method according to claim 4 or 5, characterized in that: To facilitate the control of the water and soil pressure on the tunnel face of the shield machine, the concrete plates and the uplift piles are arranged on the ground in sections, different vertical loads are arranged on each concrete plate, and the water and soil pressure on the tunnel face of the shield machine is controlled to be about 0.5D.

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