阅读说明：本技术 一种富水粉砂地层盾构下穿建筑物群沉降控制施工方法 (Settlement control construction method for water-rich silt stratum shield underpass building group ) 是由 孙伯乐 杜红波 曹建辉 应信群 张幼文 陶军武 申秦勇 薛瑞 梁卿恺 李刚柱 赵 于 2020-03-25 设计创作，主要内容包括：本发明属于隧道施工技术领域,具体涉及一种富水粉砂地层盾构下穿建筑物群沉降控制施工方法。为了解决富水粉砂软弱地层以往盾构机下穿建筑物群,沉降过大造成建筑物开裂、破损的问题。具体为在盾构掘进至影响区域范围前,通过运用岩土有限元分析软件预先对下穿建筑物群施工进行数值模型分析,得出下穿房屋时所控制的盾构参数；下穿施工过程中通过严格控制施工参数及同步注浆降低对地表及房屋基础的影响。本发明改进了以往盾构机下穿建筑物群,沉降过大造成建筑物开裂、破损的弊端,应用效果良好。在不同穿越地质情况中土压平衡盾构下穿越建筑物群施工,特别是在粉砂软弱地层中盾构下穿建构筑物施工中推广前景十分广阔。(The invention belongs to the technical field of tunnel construction, and particularly relates to a settlement control construction method for a water-rich silt stratum shield underpass building group. The problem that a building is cracked and damaged due to excessive settlement when a previous shield machine penetrates a building group in a water-rich silt weak stratum is solved. Before the shield is tunneled to an influence area range, carrying out numerical model analysis on construction of a downward-passing building group in advance by using rock-soil finite element analysis software to obtain shield parameters controlled during downward-passing of a house; the influence on the earth surface and the house foundation is reduced by strictly controlling construction parameters and synchronously grouting in the process of downward-penetrating construction. The invention overcomes the defects of cracking and damage of buildings caused by excessive settlement when the traditional shield machine passes through a building group, and has good application effect. The construction method has the advantages that the construction of penetrating through a building group under the earth pressure balance shield under different penetrating geological conditions is realized, and the popularization prospect is very wide in the construction of penetrating through the building under the shield in a silt weak stratum.)

1. A settlement control construction method for a water-rich silt stratum shield downward-penetrating building group is characterized in that before the shield is tunneled to the range of the building group, numerical model analysis is carried out on the downward-penetrating building group construction process in advance by using rock-soil finite element analysis software, and shield construction parameters controlled when the downward-penetrating building group is primarily obtained; construction parameters are strictly controlled in the process of downward penetrating construction, and influence on the ground surface and the house foundation is reduced by matching with synchronous grouting.

2. The construction method for controlling the settlement of the shield run-through building group in the water-rich silt stratum according to claim 1, which specifically comprises the following steps:

s1) before downward penetration, a unit grid model is established by using MIDASGTSNX software, and then the unit grid model is led into F L AC3D for side penetration construction fluid-solid coupling calculation to realize numerical simulation risk analysis and evaluation;

s2) trial excavation stage construction; taking the first 45m-55m after the shield machine reaches the influence range as a simulation test section; recording shield thrust, propelling speed, soil output and optimal parameters of synchronous grouting in the crossing process of the shield tunneling machine in the trial tunneling process; optimizing control parameters of shield thrust, propulsion speed, soil output and synchronous grouting obtained in the test section according to the analysis result of the step S1; monitoring the earth surface, underground pipelines, the ground and underground buildings in the pilot excavation construction process;

s3), normally advancing according to the construction parameters optimized in the trial excavation stage, and continuing construction monitoring according to the monitoring standard of the trial excavation stage in the advancing process; the propulsion mileage is controlled in the construction process, and the axis deviation of the tunnel is controlled; the surface heave is controlled within the range of +/-5 mm;

in the section of the relaxation curve and the circular curve, the deviation of the position of the lining ring from the mileage in the longitudinal axis direction of the tunnel design, the direction vertical to the design axis of the tunnel and the elevation in the design is not more than 50mm, and the deviation of the upper part, the lower part, the left part and the right part of the axis of the tunnel is controlled within the range of 50 mm.

3. The construction method for controlling the settlement of the shield tunneling downward-penetrating building group in the water-rich silt stratum as claimed in claim 2, wherein in the construction process of the trial excavation stage of step S2; monitoring the deformation of the earth surface by adopting a settlement monitoring point distributed along the axis direction, wherein the settlement monitoring point comprises a deep settlement point and a cross section monitoring point; setting settlement points for underground pipelines; on the basis of investigation and research on buildings, laying settlement monitoring points, inclination monitoring points and crack monitoring points on the buildings in the range of the shield tunneling machine influence area on two sides of an axis; and monitoring all monitoring points in the trial excavation stage at least 2 times per day.

4. The construction method for controlling the sinking of the shield run-through building group in the water-rich silt stratum as claimed in claim 2, wherein the following parameters are controlled in the normal advancing process of step S3:

1) pressing soil; in the construction process, the proposed soil pressure is set to be 0.1-0.12 MPa, and after entering a weak soil body, the pressure of a soil bin is controlled to avoid severe fluctuation of the soil pressure; the fluctuation range of the soil pressure of each ring of tunneling is controlled within 0.02 MPa;

2) soil output amount; the soil output is controlled to be 125 percent of the theoretical soil output value, namely the soil output per ring is controlled to be 47.2-49.2 m³In the construction process, the soil output is adjusted according to the ground settlement monitoring data, and meanwhile, a foaming agent is added into the soil bin to control the soil output stability of the screw conveyor;

3) assembling the duct pieces; mounting pipe pieces from bottom to top;

4) controlling the propulsion speed and rectifying the attitude; the average tunneling speed of construction of the crossing section is 20mm/min, the propelling speed, the cutter head rotating speed, the unearthing speed and the grouting speed are kept to be matched, and overlarge and over-urgent deviation correction is avoided in downward crossing construction; reducing the influence on building groups by combining the turning ring segments and segment pasting ultra-moderate deviation rectification according to the plane curve;

5) synchronously grouting; the cement is ordinary portland cement, and grouting hole sites are arranged on two sides of the bottom of the tunnel; synchronous grouting is carried out to keep constant-speed, uniform and continuous pressure grouting; and simultaneously controlling the grouting pressure and the grouting amount, namely finishing grouting when the grouting pressure reaches a set value and the grouting amount reaches over 90 percent of a designed value.

5. The construction method for controlling settlement of the shield underpass building group in the water-rich silt stratum according to claim 4, wherein the segment assembling process comprises the following steps: cleaning the pipe piece; sticking a waterproof rubber sealing gasket; rectifying the deviation of the duct piece; and controlling the assembling ellipticity.

6. The construction method for controlling the settlement of the shield run-through building group in the water-rich silt stratum as claimed in claim 5, wherein the segment rectification comprises:

1) when the trend of deviating from the axis occurs, the stroke difference of the jack is adjusted in time or a deviation rectifying wedge is attached to correct the deviation;

2) the deviation rectification of the plane axis is controlled by adjusting the stroke difference of a left jack and a right jack; the deviation correction amount is controlled within 4mm in each ring;

3) checking the gap between the segment of the previous ring and the shield tail before assembling the segments, and determining the correction amount and measures of the ring by combining a front ring result report;

4) when the tunnel turns or corrects the axis of the tunnel, correcting the deviation by installing wedge-shaped pipe pieces in different directions; or asbestos rubber plates with different thicknesses are adhered to the positions, back to the jack annular seam, of the lining ring in sections, wherein the thickness of each asbestos rubber plate is 1-6 mm; after removing impurities on the sticking surface, sticking the stone rubber plate on the lining ring surface by using a single-component neoprene-phenolic adhesive; when the thickness of the adhered asbestos rubber plate is more than 6mm, a 1.5mm to 3mm full-expansion rubber sheet is adhered to the back of the water-stopping sealing gasket at the same position;

5) the shield longitudinal slope is controlled by adopting a slope stabilizing method, and the curvature correction can not be carried out by sticking the asbestos rubber sheet when the shield machine is propelled according to the design curve completely.

7. The construction method for controlling the settlement of the downward-penetrating building group of the shield in the water-rich silt stratum according to claim 5, is characterized in that after the pipe pieces are assembled into a ring, the ovality of the gap between the outer wall of the pipe piece and the inner wall of the shield shell is measured by a steel tape or a ruler, and the ovality is measured once every ring of the pipe pieces; the method for adjusting the splicing ellipticity comprises the following steps:

1) applying pressure to the duct piece in the short axial direction by using the assembling jacks to perform rounding treatment;

2) fastening the hoop screw in the short axis direction and the long axis direction;

3) tightening the circumferential bolt and the longitudinal bolt for multiple times;

after each ring of linings are assembled, the jacks are closed in time, the longitudinal and circumferential bolts are screwed down simultaneously, and the longitudinal bolts are tightened again under the action of the jacking force of the jacks when the next ring is pushed; after the annular duct piece is pushed out of the shield tail, the longitudinal and annular bolts are tightened again according to the ovality of the assembled ring so as to reduce the opening angle and the bell mouth of the duct piece assembly.

8. The construction method for controlling the settlement of the shield downward-penetrating building group in the water-rich silt stratum according to claim 3, wherein the shield grouting adopts thick slurry synchronous grouting, the amount of each ring of grouting is controlled to be 180-210% of the 'building clearance', and the grouting pressure is 0.1-0.3 MPa; the grouting speed and the propulsion are kept synchronous, namely grouting is carried out while the shield is propelled, and the grouting is correspondingly stopped after the propulsion is stopped; the grouting amount is 4.27-4.98m 3/ring;

before the shield reaches the lower part of the building group, the change of the tunnel face soil pressure caused by the building foundation stacking of the building group is calculated, the cut pressure value is adjusted, and the synchronous grouting pressure is increased by 20 percent so as to effectively fill the overbreak gap.

9. The construction method for controlling the settlement of the shield downward-penetrating building group in the water-rich silt stratum as claimed in claim 3, wherein the material ratio of the synchronous grouting is that each 1m3 of grout comprises: 150kg of cement, 350kg of fly ash, 870kg of sand 770, 150kg of bentonite 100 and 450kg of water 400.

10. The settlement control construction method for the water-rich silt stratum shield downward-penetrating building group as claimed in claim 2, wherein two sets of layered settlement observation points are arranged within 50m before the shield downward-penetrating building group before the trial excavation stage; obtaining the stratum settlement change condition after the shield passes through the first group of data, and preliminarily determining various shield tunneling parameters; and verifying various parameters of the shield tunneling through the second group of data so as to further adjust and correct the parameters.

Technical Field

The invention belongs to the technical field of tunnel construction, and particularly relates to a settlement control construction method for a water-rich silt stratum shield underpass building group.

Background

The shield method is a fully mechanical construction method in the construction of the underground excavation method, and along with the vigorous development of the rail transit construction of various big cities, the shield method is widely applied to the construction due to the characteristics of good safety, high efficiency and low noise. When the shield is used for tunneling in a water-rich weak stratum, due to the poor stability of the water-rich weak stratum, the settlement is difficult to control, and some buildings are long in construction age, poor in structural stability and weak in ground surface deformation resistance, if the settlement is improperly controlled, the ground surface and the buildings can be excessively settled, so that the buildings are cracked, inclined and even collapsed, and therefore great economic loss and severe social influence are caused.

The shield underpass building is complete in theory at present, mainly focuses on secondary grouting, intermittent tracking grouting, sleeve valve pipe grouting and the like, but has less research on shield parameter control in a silt stratum, and meanwhile, related data is consulted for display, and the adopted grouting reinforcement measures have a common control effect on tunnel settlement.

Disclosure of Invention

The invention aims to solve the problems that a previous shield machine penetrates a building group downwards and is excessively settled to cause cracking and damage of a building in a water-rich silt weak stratum.

Before the shield is tunneled to the range of the building group, carrying out numerical model analysis on the construction process of the downward-passing building group in advance by using rock-soil finite element analysis software, and preliminarily obtaining shield construction parameters controlled when the downward-passing building group is tunneled; construction parameters are strictly controlled in the process of downward penetrating construction, and influence on the ground surface and the house foundation is reduced by matching with synchronous grouting.

The invention specifically comprises the following parts:

s1) before downward penetration, a unit grid model is established by using MIDASGTSNX software, and then the unit grid model is led into F L AC3D for side penetration construction fluid-solid coupling calculation to realize numerical simulation risk analysis and evaluation;

s2) trial excavation stage construction; taking the first 45m-55m after the shield machine reaches the influence range as a simulation test section; recording shield thrust, propelling speed, soil output and optimal parameters of synchronous grouting in the crossing process of the shield tunneling machine in the trial tunneling process; optimizing control parameters of shield thrust, propulsion speed, soil output and synchronous grouting obtained in the test section according to the analysis result of the step S1; monitoring the earth surface, underground pipelines, the ground and underground buildings in the pilot excavation construction process;

s3), normally advancing according to the construction parameters optimized in the trial excavation stage, and continuing construction monitoring according to the monitoring standard of the trial excavation stage in the advancing process; the propulsion mileage is controlled in the construction process, and the axis deviation of the tunnel is controlled; the surface heave is controlled within the range of +/-5 mm;

in the section of the relaxation curve and the circular curve, the deviation of the position of the lining ring from the mileage in the longitudinal axis direction of the tunnel design, the direction vertical to the design axis of the tunnel and the elevation in the design is not more than 50mm, and the deviation of the upper part, the lower part, the left part and the right part of the axis of the tunnel is controlled within the range of 50 mm.

Further, in the trial excavation stage construction process of step S2; monitoring the deformation of the earth surface by adopting a settlement monitoring point distributed along the axis direction, wherein the settlement monitoring point comprises a deep settlement point and a cross section monitoring point; setting settlement points for underground pipelines; on the basis of investigation and research on buildings, laying settlement monitoring points, inclination monitoring points and crack monitoring points on the buildings in the range of the shield tunneling machine influence area on two sides of an axis; and monitoring all monitoring points in the trial excavation stage at least 2 times per day.

Further, the following parameters are controlled during the normal propulsion process in step S3:

1) pressing soil; in the construction process, the proposed soil pressure is set to be 0.1-0.12 MPa, and after entering a weak soil body, the pressure of a soil bin is controlled to avoid severe fluctuation of the soil pressure; the fluctuation range of the soil pressure of each ring of tunneling is controlled within 0.02 MPa;

2) soil output amount; the soil output is controlled to be 125% of a theoretical soil output value, namely the soil output of each ring is controlled to be 47.2-49.2 m3, the soil output is adjusted according to ground settlement monitoring data in the construction process, and meanwhile, a foaming agent is added into the soil bin to control the soil output stability of the screw conveyor;

3) assembling the duct pieces; mounting pipe pieces from bottom to top;

4) controlling the propulsion speed and rectifying the attitude; the average tunneling speed of construction of the crossing section is 20mm/min, the propelling speed, the cutter head rotating speed, the unearthing speed and the grouting speed are kept to be matched, and overlarge and over-urgent deviation correction is avoided in downward crossing construction; reducing the influence on building groups by combining the turning ring segments and segment pasting ultra-moderate deviation rectification according to the plane curve;

5) synchronously grouting; the cement is ordinary portland cement, and grouting hole sites are arranged on two sides of the bottom of the tunnel; synchronous grouting is carried out to keep constant-speed, uniform and continuous pressure grouting; and simultaneously controlling the grouting pressure and the grouting amount, namely finishing grouting when the grouting pressure reaches a set value and the grouting amount reaches over 90 percent of a designed value.

Specifically, the segment assembling process comprises: cleaning the pipe piece; sticking a waterproof rubber sealing gasket; rectifying the deviation of the duct piece; and controlling the assembling ellipticity.

Further, the segment rectification comprises:

1) when the trend of deviating from the axis occurs, the stroke difference of the jack is adjusted in time or a deviation rectifying wedge is attached to correct the deviation;

2) the deviation rectification of the plane axis is controlled by adjusting the stroke difference of a left jack and a right jack; the deviation correction amount is controlled within 4mm in each ring;

3) checking the gap between the segment of the previous ring and the shield tail before assembling the segments, and determining the correction amount and measures of the ring by combining a front ring result report;

4) when the tunnel turns or corrects the axis of the tunnel, correcting the deviation by installing wedge-shaped pipe pieces in different directions; or asbestos rubber plates with different thicknesses are adhered to the positions, back to the jack annular seam, of the lining ring in sections, wherein the thickness of each asbestos rubber plate is 1-6 mm; after removing impurities on the sticking surface, sticking the stone rubber plate on the lining ring surface by using a single-component neoprene-phenolic adhesive; when the thickness of the adhered asbestos rubber plate is more than 6mm, a 1.5mm to 3mm full-expansion rubber sheet is adhered to the back of the water-stopping sealing gasket at the same position;

5) the shield longitudinal slope is controlled by adopting a slope stabilizing method, and the curvature correction can not be carried out by sticking the asbestos rubber sheet when the shield machine is propelled according to the design curve completely.

Furthermore, after the pipe pieces are assembled into a ring, the ovality of the pipe pieces is timely checked by measuring the gap between the outer wall of the pipe pieces and the inner wall of the shield shell by using a steel tape or a ruler; the method for adjusting the splicing ellipticity comprises the following steps:

1) applying pressure to the duct piece in the short axial direction by using the assembling jacks to perform rounding treatment;

2) fastening the hoop screw in the short axis direction and the long axis direction;

3) tightening the circumferential bolt and the longitudinal bolt for multiple times;

after each ring of linings are assembled, the jacks are closed in time, the longitudinal and circumferential bolts are screwed down simultaneously, and the longitudinal bolts are tightened again under the action of the jacking force of the jacks when the next ring is pushed; after the annular duct piece is pushed out of the shield tail, the longitudinal and annular bolts are tightened again according to the ovality of the assembled ring so as to reduce the opening angle and the bell mouth of the duct piece assembly.

Furthermore, thick slurry is adopted for shield grouting, the amount of each ring is controlled to be 180-210% of the 'building gap', and the grouting pressure is 0.1-0.3 MPa; the grouting speed and the propulsion are kept synchronous, namely grouting is carried out while the shield is propelled, and the grouting is correspondingly stopped after the propulsion is stopped; the grouting amount is 4.27-4.98m 3/ring;

before the shield reaches the lower part of the building group, the change of the tunnel face soil pressure caused by the building foundation stacking of the building group is calculated, the cut pressure value is adjusted, and the synchronous grouting pressure is increased by 20 percent so as to effectively fill the overbreak gap.

Specifically, the material ratio of synchronous grouting is that each 1m3 of grout comprises: 150kg of cement, 350kg of fly ash, 870kg of sand 770, 150kg of bentonite 100 and 450kg of water 400.

Further, before a trial excavation stage, two groups of layered settlement observation points are arranged in a range of 50m before the shield penetrates a building group; obtaining the stratum settlement change condition after the shield passes through the first group of data, and preliminarily determining various shield tunneling parameters; and verifying various parameters of the shield tunneling through the second group of data so as to further adjust and correct the parameters.

Compared with the prior art, the invention has the advantages that:

numerical model analysis is carried out on the construction of a downward-passing building group in advance by using MIDAS GTS NX software, so as to obtain shield parameters controlled during downward-passing of a house; and in the process of underpass construction, construction parameters are strictly controlled and secondary grouting is carried out to ensure that the earth surface and the house foundation are not obviously influenced. The method basically avoids the condition of reinforcing the building group, saves the cost of taking reinforcing measures for the building group, and saves a large amount of manpower, material resources, financial resources and construction period investment in the reinforcing construction compared with the similar shield underpass building group project in the same region. The invention overcomes the defects of cracking and damage of buildings caused by excessive settlement when the traditional shield machine passes through a building group, and has good application effect. The construction method has the advantages that the construction of penetrating through a building group under the earth pressure balance shield under different penetrating geological conditions is realized, and the popularization prospect is very wide in the construction of penetrating through the building under the shield in a silt weak stratum.

Drawings

FIG. 1 is a flow chart of the present invention.

Fig. 2 is a schematic view of the gap of the shield tail.

Fig. 3 is a schematic diagram of synchronous grouting and timely grouting.

Detailed Description

The present invention will be further described with reference to the following examples. 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.